In-game Nieuport 28.C1 & Albatros D.Va sustained turn rate comparison to C++ simulations

[No.23_Starling]

13 minutes ago, J99_Sizzlorr said:

I don't want things to be added to the sim I was just curious if Holtzauge's simulation did take that into account. No need to be rude. I am not your summarizer and I don't have that book so I can not give you a page number. Geez what is wrong with you? Don't know what agenda you are pushing with the S.E.5a though but if you would have read the thread I pointed you to you would see some graphs

 

This is great. Silly question but is the AUV just the AU? If so the first chart suggests that it should produce a little under 200hp at SL. Any idea if their data is calculated or taken from actual physical tests? Do you have the book the chart originated from? I’d love a copy 

 

[J99_Sizzlorr]

1 minute ago, US103_Rummell said:

This is great. Silly question but is the AUV just the AU? If so the first chart suggests that it should produce a little under 200hp at SL. Any idea if their data is calculated or taken from actual physical tests? Do you have the book the chart originated from? I’d love a copy 

 

You are not even reading my posts do you ? ? I told you already which book the first chart comes from assuming you are talking about that and I also told you that I do not own that book.

[Holtzauge]

To answer all these questions about the simulations assumptions now will take too long so I will try reply sometime tomorrow: It’s Saturday evening here and I’m enjoying some good food and wine and hopefully you guys will be able to do the same! Cheers! 

[No.23_Starling]

7 minutes ago, J99_Sizzlorr said:

You are not even reading my posts do you ? ? I told you already which book the first chart comes from assuming you are talking about that and I also told you that I do not own that book.

So you’ve quoted a book without more detail on the data - real tests or calculated? The point on the fuel is that your URL does not give detailed information on the adoption of the fuel, which planes and Jastas were issued it and when etc etc. The higher octane fuel in the ww2 modules was likely added thanks to evidence of time of adoption and which planes it involved.

 

My problem is you and others shooting me down (not in the sim, lol) without providing detailed evidence to back up your opinions. For example, I’ve yet to see data around the CL2 Bekker despite buying Schlachtflieger - still a good read though - nor data around Heinecke parachutes on their effectiveness past initial tests.

 

My point on the SE5a is that the extant data does not point the HS 200hp variant being significantly different in performance to the 200hp Viper at multiplayer altitudes.

 

I suspect you’re right about the fuel adoption for the Merc engines but it’s fair of me to ask for specifics about its usage, and also fair to say that the URL you posted is a long inconclusive discussion.

 

Sorry if I missed your book reference, I’d still like a copy.

[J99_Sizzlorr]

My intial question had nothing to do with you or without you trying to push the S.E.5a, I was just curious then you started the your source is not good enough stuff and that it can not be taken seriously even though the people in the thread are the ones you read and buy books from. Also the the Reichsamt für Luft- und Kraftwesen contributed to the book. And the source you quote is Jon G. which should be read with a grain of salt. You can't get that book right now for a sane prize in a good quality and even if you had a page number you couldn't understand the German language...things in history happened even if they were not documented or it's documentation got destroyed or the only thing you have is a secondary source. You need to stay open minded...

Edited February 4, 2023 by J99_Sizzlorr

[Holtzauge]

The book covers both the question connected to propellers, power levels and fuels each with their own dedicated chapters. Including why I chose the power levels I did in the simulations. But here is a short summary anyway:

 

Regarding the S.E.5a, there should be no major difference if it’s fitted with a 4 or 2 blade prop as long as the design is done right, i.e. that the blades have enough solidity to absorb the power.

 

When it comes to the fuels and power output in German engines, I think the answer is in some sense connected to the Mercedes D.IIIaü itself: The Germans went to great lengths to design an elaborate carburetor for that engine with altitude compensation. And if you could simply have run an over-compressed engine at full throttle at low levels with the fuel generally available on Jasta-level, then there would have been be no need for that or a special carburetor in the first place.

 

For sure, blending Benzol into the fuel resulted in a higher octane fuel so on a theoretical level both the D.IIIaü and BMW DIIIa could be run at higher throttle settings, although that would have required another carburetor on the D.IIIaü. On the BMW it could have been done manually by using the second “Höhengas” throttle so no problem there.

 

But to what extent was this type of fuel used? It would require logistics to maintain the supply of Benzol and would only be of value under around 2100 m for the BMW, and 1800 m for the over-compressed Mercedes.

 

Just speculation for sure, but I think it’s likely that we care because in-game this is an issue for server battles, while IRL the Germans did not care that much about the low altitude performance since fighting late in the war was done at high altitude where the engines did just fine with straight run Leichtbenzin.

 

And another thing: Pilot accounts of running engines at higher levels than rated prove nothing: Just because you get away with flying an engine that is detonating once, does not mean it will not blow up next time you try it.

 

Edited February 5, 2023 by Holtzauge

[ZachariasX]

You can add all the benzol you want, you will not get 260 hp from the BMW IIIa in the aircraft due to the way the carburetor is designed and set. In order to get the cyan graph on the left plot reaching almost 260 hp, you'd have to fetch an arrangement that was used on a Hisso with a mixture lever. In the cockpit back then, the yellow line is about what you can have due to the set mixture ratio. Changin that requires you to change the fuel tubes in the carb and will conversly result in an overly rich mixture at altitude, hitting mileage and degrading performance. In essence, by letting engines run out of spec at an altitude, where there's not much relevance to it while having a sub par engine up where it matters, you get some 10% power over doing as you should. How smart is that?

 

Furthermore, different fuel types have different burn efficiencies at given mixture ratios. The German engines set the mixture with the diameter of the fuel pipe in the carb, the engine running far lean of peak. The fuel mixture was set to be optimal at operating altitude, to where it was progressively enriching. For instance, you could simply run the engine on pure alcohol, but that would mean you'd about have twice the fuel flow (and half the mileage). But you could get all the power you want from the engine, run it at compressions of modern engines (and just let it explode revving up).

 

Besides, seeing how long Chills engine lasted, by giving it the best fuel, the best lubricant, the most attention, you'd be definitely fighting for the Entente letting your squadron use higher ratings than stated in the manuals.

 

Grounded is grounded, regardless whether shot down or engines requiring rebuild. Given how "abundant" these engines were, I'd say they couldn't change them as readily as they may have liked. Hence, I'd say it would have been an immensly stupid idea srcrewing up logistics with alternate fuel types and engine spares just to have more defective engines.

 

I definitely should fetch myself a copy of the Dechamps book though. I'll find one.

[Holtzauge]

IIRC then I did manage to find it (the Dechamps) book scanned and possible to "loan" via some university site but that was somewhere in the US and I was not allowed to borrow/read it from Sweden, even in digital format. Maybe if you could find it @ZachariasX, one of our US based forum friends could borrow it?

[No.23_Starling]

1 hour ago, Holtzauge said:

The book covers both the question connected to propellers, power levels and fuels each with their own dedicated chapters. Including why I chose the power levels I did in the simulations. But here is a short summary anyway:

 

Regarding the S.E.5a, there should be no major difference if it’s fitted with a 4 or 2 blade prop as long as the design is done right, i.e. that the blades have enough solidity to absorb the power.

 

When it comes to the fuels and power output in German engines, I think the answer is in some sense connected to the Mercedes D.IIIaü itself: The Germans went to great lengths to design an elaborate carburetor for that engine with altitude compensation. And if you could simply have run an over-compressed engine at full throttle at low levels with the fuel generally available on Jasta-level, then there would have been be no need for that or a special carburetor in the first place.

 

For sure, blending Benzol into the fuel resulted in a higher octane fuel so on a theoretical level both the D.IIIaü and BMW DIIIa could be run at higher throttle settings, although that would have required another carburetor on the D.IIIaü. On the BMW it could have been done manually by using the second “Höhengas” throttle so no problem there.

 

But to what extent was this type of fuel used? It would require logistics to maintain the supply of Benzol and would only be of value under around 2100 m for the BMW, and 1800 m for the over-compressed Mercedes.

 

Just speculation for sure, but I think it’s likely that we care because in-game this is an issue for server battles, while IRL the Germans did not care that much about the low altitude performance since fighting late in the war was done at high altitude where the engines did just fine with straight run Leichtbenzin.

 

And another thing: Pilot accounts of running engines at higher levels than rated prove nothing: Just because you get away with flying an engine that is detonating once, does not mean it will not blow up next time you try it.

 

 

Very helpful reply as always. Looking at additional SE5a data (will double check source) from Mr Baer we see the same story which is the 1917 200hp engine is slightly weaker in performance at high altitude. As per your point on the prop, I still dont see evidence that there was a strong turning SE5a in 1917, nor that the 200hp HS engine was substantially worse below 10k feet where most Flying Circus MP combat happens. 

 

This is important because the opinion of one member of the community can start to gain legs and become accepted wisdom when the data/science dont match.

 

As for the fuel variants, as you say, most combat was expected over 2km and there was a carb developed for the iiiau engine specifically to address this so it's almost a moot point. The danger starts in MP when it is available to all German scouts; everyone will take it, because why wouldn't you? I have no issue with fuel variants being in the game as they were likely available, but let's not kid ourselves that every iiiau engine used it as I've yet to see any evidence to make this the case. The same applies to cannons on every 2-seater, unlimited Dr1s in 1917 maps, and balloon guns on every SPAD.

 

[Holtzauge]

2 hours ago, US103_Rummell said:

 

Very helpful reply as always. Looking at additional SE5a data (will double check source) from Mr Baer we see the same story which is the 1917 200hp engine is slightly weaker in performance at high altitude. As per your point on the prop, I still dont see evidence that there was a strong turning SE5a in 1917, nor that the 200hp HS engine was substantially worse below 10k feet where most Flying Circus MP combat happens. 

 

This is important because the opinion of one member of the community can start to gain legs and become accepted wisdom when the data/science dont match.

 

As for the fuel variants, as you say, most combat was expected over 2km and there was a carb developed for the iiiau engine specifically to address this so it's almost a moot point. The danger starts in MP when it is available to all German scouts; everyone will take it, because why wouldn't you? I have no issue with fuel variants being in the game as they were likely available, but let's not kid ourselves that every iiiau engine used it as I've yet to see any evidence to make this the case. The same applies to cannons on every 2-seater, unlimited Dr1s in 1917 maps, and balloon guns on every SPAD.

 

 

Leaving the issue with the different fuel combinations aside, the problem with all these performance numbers is to determine which are representative? I think comparing the columns for the two Viper trials illustrates this in a good way. Could be that one engine was pristine and the other a tired old warhorse that had been mistreated. Or did they have very different propellers on them? Or both? I assume a 210 hp Hisso in my simulations for the S.E.5a and I am close to the red highlighted column both in terms of speed and climb with just about the same weight.

 

But on the other hand I have seen other data  for the S.E.5a which has climb times in the order of the other Viper column in your table. I write a bit about this (diverging data) in the tuning data section of the book but I don’t see any easy answers.

 

However, the longer Viper climb time seem pessimistic to me if one considers what the SPAD is usually credited with doing with Hisso engine which is close to the one on the S.E.5a. In addition, looking at power-, wing- and span loadings I’m more inclined to believe that the shorter Viper climb time is more representative. At least when looking at power levels in the Viper S.E.5a and Hisso SPAD, since an uncompressed engine should drop in power with altitude close to the drop in density irrespective if it’s a Viper or a Hisso.

 

In addition: Look at the two tables with data for 150 hp Hisso to the left of the leftmost Viper 200 hp column: Climb times to 15,000 ft:  19 m 40 s and 19 m 55 s both with the same A.D.662 prop as the 200 hp Viper which needs  24 m 30 s. And the "150 hp" Hisso with the higher compression ratio climbs worse? The weights are not that different either. How does one make any sense of that?

 

PS: The “150 hp” Hisso with compression ratio 5.6 supposedly delivered 192 hp. The Viper “200 hp” supposedly delivered 210 hp. All very confusing if you ask me……

 

 

Edited February 5, 2023 by Holtzauge

[No.23_Starling]

1 hour ago, Holtzauge said:

 

Leaving the issue with the different fuel combinations aside, the problem with all these performance numbers is to determine which are representative? I think comparing the columns for the two Viper trials illustrates this in a good way. Could be that one engine was pristine and the other a tired old warhorse that had been mistreated. Or did they have very different propellers on them? Or both? I assume a 210 hp Hisso in my simulations for the S.E.5a and I am close to the red highlighted column both in terms of speed and climb with just about the same weight.

 

But on the other hand I have seen other data  for the S.E.5a which has climb times in the order of the other Viper column in your table. I write a bit about this (diverging data) in the tuning data section of the book but I don’t see any easy answers.

 

However, the longer Viper climb time seem pessimistic to me if one considers what the SPAD is usually credited with doing with Hisso engine which is close to the one on the S.E.5a. In addition, looking at power-, wing- and span loadings I’m more inclined to believe that the shorter Viper climb time is more representative. At least when looking at power levels in the Viper S.E.5a and Hisso SPAD, since an uncompressed engine should drop in power with altitude close to the drop in density irrespective if it’s a Viper or a Hisso.

 

In addition: Look at the two tables with data for 150 hp Hisso to the left of the leftmost Viper 200 hp column: Climb times to 15,000 ft:  19 m 40 s and 19 m 55 s both with the same A.D.662 prop as the 200 hp Viper which needs  24 m 30 s. And the "150 hp" Hisso with the higher compression ratio climbs worse? The weights are not that different either. How does one make any sense of that?

 

PS: The “150 hp” Hisso with compression ratio 5.6 supposedly delivered 192 hp. The Viper “200 hp” supposedly delivered 210 hp. All very confusing if you ask me……

 

 

 

That table above is taken from Bruce, 1914-1918 British Aeroplanes, used by AnP back in the Rise of Flight days for his rework of the SE5a flight model.

 

I am with you on the confusion of the engines. Most sources (Guttman, Bruce) talk to 3 main variants: SE5 150hp HS, SE5a 200hp HS (SPAD XIII engine), and the SE5a 200hp Viper (150hp HS with higher compression ratio), as do the diaries from 56 squadron (see Revell, High in the Empty Blue, The History of 56 Squadron RFC RAF 1916-1919, p.79). It's possible that there were several other variants floating around such as the 180hp HS (Spad VII upgraded version), 220hp HS (SPAD XIII upgrade), and the Adder variants which were also tested. Bruce in the Profile Publication on the Dolphin P.9 mentions that the RFC upgraded the HS 200hp engines to the 220hp 5.3:1 compression ratio, so it's likely the SE5as still flying with that engine also saw that upgrade.

 

There's clearly a difference in performance between the first batch of SE5s flown by 56 squadron, but a lot of the data for the Viper and HS 200hp is closely matched, and these are the two engines which appear most in the sources. I dont see compelling evidence to suggest that a 200hp HS 4 bladed prop variant is necessary for 1917 scenarios when the performance appears so similar with the exception of high alt where very little multiplayer flying happens.

 

As for MP balancing, if the iiiau engine was added you would expect to also see the HS 220hp (238hp max) for all the in-line Allied scouts, and probably some Bentley Camels too.

 

Edited February 5, 2023 by US103_Rummell

[Holtzauge]

48 minutes ago, US103_Rummell said:

 

That table above is taken from Bruce, 1914-1918 British Aeroplanes, used by AnP back in the Rise of Flight days for his rework of the SE5a flight model.

 

I am with you on the confusion of the engines. Most sources (Guttman, Bruce) talk to 3 main variants: SE5 150hp HS, SE5a 200hp HS (SPAD XIII engine), and the SE5a 200hp Viper (150hp HS with higher compression ratio), as do the diaries from 56 squadron (see Revell, High in the Empty Blue, The History of 56 Squadron RFC RAF 1916-1919, p.79). It's possible that there were several other variants floating around such as the 180hp HS (Spad VII upgraded version), 220hp HS (SPAD XIII upgrade), and the Adder variants which were also tested. Bruce in the Profile Publication on the Dolphin P.9 mentions that the RFC upgraded the HS 200hp engines to the 220hp 5.3:1 compression ratio, so it's likely the SE5as still flying with that engine also saw that upgrade.

 

There's clearly a difference in performance between the first batch of SE5s flown by 56 squadron, but a lot of the data for the Viper and HS 200hp is closely matched, and these are the two engines which appear most in the sources. I dont see compelling evidence to suggest that a 200hp HS 4 bladed prop variant is necessary for 1917 scenarios when the performance appears so similar with the exception of high alt where very little multiplayer flying happens.

 

As for MP balancing, if the iiiau engine was added you would expect to also see the HS 220hp (238hp max) for all the in-line Allied scouts, and probably some Bentley Camels too. Even with the upgrade, in that scenario the Dvau and P Diiiau is likely to still not be particularly competitive - hence Jastas scrambled for the new DVIIaus and DVIIFs.

 

 

Yes, making sure that suitable aircraft engine combinations are modeled in-game is a very good point I think. Some purists will baulk at the word “game balance” but I don’t think it necessarily need to be bad thing: I think a judicious selection of the aircraft that actually were in service at a certain time could make for interesting game play: The classic setup is of course a TnB scout and a BnZ scout. But if one shines on all points then the fun goes out of it. Both need to have strong and weak points. And herein lies the art of doing a game release: Ensure that the plane set is both historical and also selected so that the game is fun to fly.

 

Here I think C++ simulations could help: Investigate how different aircraft with different engine combinations perform and use this data to decide what planes to include with what engine and fuel combinations.

 

I think the Albatros D.Va is actually a good example of this: The C++ simulations I have done indicate that it should with the 180 hp standard Mercedes D.IIIa engine modeled in-game today not even turn very well. So if that were to be adjusted at the same time as the Nieuport 28.C1’s turn rate is dialed up how fun would it be flying those two against each other?

 

The only way I see out of that dilemma is to give the D.Va a Mercedes D.IIIaü engine.

 

This was just an example, but the same applies to the other aircraft as well of course. But step one to me is to agree on a baseline: How should the different aircraft we have today perform against the best data we have available, both historical and simulations.

 

Once there is a common ground there, then looking at which plane set, with which engines and with which fuels seems like a much easier proposition.

 

 

[J99_Sizzlorr]

4 hours ago, US103_Rummell said:

As for the fuel variants, as you say, most combat was expected over 2km and there was a carb developed for the iiiau engine specifically to address this so it's almost a moot point. The danger starts in MP when it is available to all German scouts; everyone will take it, because why wouldn't you? I have no issue with fuel variants being in the game as they were likely available, but let's not kid ourselves that every iiiau engine used it as I've yet to see any evidence to make this the case. The same applies to cannons on every 2-seater, unlimited Dr1s in 1917 maps, and balloon guns on every SPAD.

 

As I understand it the Fliegerbenzin was basically fuel mixed with Ethanol. So I don't see why you come to the opinion that it would be in short supply? By mixing Ethanol to their fuel they basically streched their fuel supplies by how much Ethanol they added and Ethanol was easier for the Germans to get their hands on at the beginning of 1918 than fuel.

 

There is also a rumor going around that the "F" designation on the BMW Fokker D.VII stands for Fliegerbenzin. So that the mechanics knew what fuel to use for the BMW engine.

 

Also the carburator might be the bottle neck wouldn't the higher octane fuel give the engine more leeway in using it at full power further below 2000m since the Fliegerbenzin did not detonate as quickly as other mixtures? Since benzol has a lower stoichiometric AFR than gasoline (13:1 vs 15:1).

Also the Brits did overcome the bottleneck of the carburator by using a "blower" to obtain a rich mixture power output for the engine at ground level up to 1600 rpm - 234 hp at 1400rpm, rising to 254 hp at 1600 rpm for a 1 hour test. It is not clear what type of fuel was used in this test. After 11 hours in various short runs the base of a cylinder broke away. So when the carburator is set in a very lean position wouldn't that give the engine a richer powere output at sea level?

 

As for the Görings anecdote this is the translated letter where it originated from which was irritating to me at first and was the reason I looked into the different fuel variants: 

Quote

Reports over the BMW IIIa engine.
................................................
The BMW IIIa engine continues to perform splendidly. Apart from some small deficiencies, (which are already remedied), nothing has turned out to be unfavorable. Its superiority, as compared to the other engines, (also the enemy's), is proven daily. As a rule, the "over" gas throttle position is not used under 3000 meters. Not only have we been operating in the "over" gas throttle position almost constantly throughout aerial engagement, but also at low altitude, and without any damage to the engine; (only stronger vibrating becomes apparent). Recently a pilot, who was driven down by some Spads near a balloon and had lost his orientation, flew for over a half hour with the throttle in the "over" gas position and the motor at full revs (1500-1600rpm) at a height of 100 meters pursued by the Spads. It was superior in rate to the Spads. The engine had operated smoothly and had not suffered in the slightest. Again the Geschwader, (squadron), requests it for immediate and extensive delivery and asks for the immediate start of licensed production in as many factories as possible.
gez. Göring****************
Oblt. u. Geschwader-Kommandeur.

 

Anyway the BMW engine could only achieve 185bps at 1400rpm at sea level on improper octane petrol (71 octane) and could achieve around 260bps at 1400rpm at sea level with proper octane petrol (85 octane).  This in turn would make a gain of 4.2bps per octane number it is not a big margin but there are differences.

 

In 1918 Germans had time against them. They knew pretty well when America gets ready to intervene on the battlefield it would be over, so deperate times desperate measures.

 

 

Edited February 5, 2023 by J99_Sizzlorr

[No.23_Starling]

28 minutes ago, J99_Sizzlorr said:

As I understand it the Fliegerbenzin was basically fuel mixed with Ethanol. So I don't see why you come to the opinion that it would be in short supply? By mixing Ethanol to their fuel they basically streched their fuel supplies by how much Ethanol they added and Ethanol was easier for the Germans to get their hands on at the beginning of 1918 than fuel.

 

There is also a rumor going around that the "F" designation on the BMW Fokker D.VII stands for Fliegerbenzin. So that the mechanics knew what fuel to use for the BMW engine.

 

Also the carburator might be the bottle neck wouldn't the higher octane fuel give the engine more leeway in using it at full power further below 2000m since the Fliegerbenzin did not detonate as quickly as other mixtures? Since benzol has a lower stoichiometric AFR than gasoline (13:1 vs 15:1).

Also the Brits did overcome the bottleneck of the carburator by using a "blower" to obtain a rich mixture power output for the engine at ground level up to 1600 rpm - 234 hp at 1400rpm, rising to 254 hp at 1600 rpm for a 1 hour test. It is not clear what type of fuel was used in this test. After 11 hours in various short runs the base of a cylinder broke away. So when the carburator is set in a very lean position wouldn't that give the engine a richer powere output at sea level?

 

As for the Görings anecdote this is the translated letter where it originated from which was irritating to me at first and was the reason I looked into the different fuel variants: 

 

Anyway the BMW engine could only achieve 185bps at 1400rpm at sea level on improper octane petrol (71 octane) and could achieve around 260bps at 1400rpm at sea level with proper octane petrol (85 octane).  This in turn would make a gain of 4.2bps per octane number it is not a big margin but there are differences.

 

In 1918 Germans had time against them. They knew pretty well when America gets ready to intervene on the battlefield it would be over, so deperate times desperate measures.

 

 

I read that suggestion about the F in the Aerodrome link; first time I’ve come across that but a neat idea.

 

The question is less about shortages and more about data on when/where the new fuel mixture was used. I’d need to read the primary material but it looks likely it did happen at some point, but when? Should all Merc iiiau have this fuel as a load out option from the start of 1918? You see the problem. If there isn’t the data then it’s a best guess and a matter for map makers to take a call (you and Echo etc).

 

That anecdote is a curious one, and I’d love to know if the SPAD was a VII or upgraded 220hp XIII. We know from French records that the XIIIs engines were a problem till the end of the war and many escadrilles kept VIIs (upgraded repeatedly) as a backup.

[J99_Sizzlorr]

1 hour ago, US103_Rummell said:

I read that suggestion about the F in the Aerodrome link; first time I’ve come across that but a neat idea.

 

The question is less about shortages and more about data on when/where the new fuel mixture was used. I’d need to read the primary material but it looks likely it did happen at some point, but when? Should all Merc iiiau have this fuel as a load out option from the start of 1918? You see the problem. If there isn’t the data then it’s a best guess and a matter for map makers to take a call (you and Echo etc).

 

That anecdote is a curious one, and I’d love to know if the SPAD was a VII or upgraded 220hp XIII. We know from French records that the XIIIs engines were a problem till the end of the war and many escadrilles kept VIIs (upgraded repeatedly) as a backup.

You wrote earlier:

 

6 hours ago, US103_Rummell said:

I have no issue with fuel variants being in the game as they were likely available, but let's not kid ourselves that every iiiau engine used it as I've yet to see any evidence to make this the case. The same applies to cannons on every 2-seater, unlimited Dr1s in 1917 maps, and balloon guns on every SPAD.

I say yes every high altitude engine probably used it from early 1918 onwards because they experimented with it at Adlershof. There is so much best guess for mission makers on many things, but I don't see the relation to the topic. As I was only curious on which fuel Holtzauge based his simulations. We don't know if his book will have any effect on FC, as it stands there is only a slight chance of that going to happen.

 

8 hours ago, Holtzauge said:

When it comes to the fuels and power output in German engines, I think the answer is in some sense connected to the Mercedes D.IIIaü itself: The Germans went to great lengths to design an elaborate carburetor for that engine with altitude compensation. And if you could simply have run an over-compressed engine at full throttle at low levels with the fuel generally available on Jasta-level, then there would have been be no need for that or a special carburetor in the first place.

 

For sure, blending Benzol into the fuel resulted in a higher octane fuel so on a theoretical level both the D.IIIaü and BMW DIIIa could be run at higher throttle settings, although that would have required another carburetor on the D.IIIaü. On the BMW it could have been done manually by using the second “Höhengas” throttle so no problem there.

 

But to what extent was this type of fuel used? It would require logistics to maintain the supply of Benzol and would only be of value under around 2100 m for the BMW, and 1800 m for the over-compressed Mercedes.

I think the elaborate carburetor was designed before Fliegerbenzin was produced. The type was used as Germans had a shortage of fuel by the beginning of 1918. Adding Benzol streched their supplies so why wouldn't you do it? Again desperte times desperate measures.

 

Edit: I am also aware that pilot accounts  proof nothing, it just got me to digg into the different fuel variants because it irritated me when I read it that is why I brought it up here. My question still stands unsawered I am afraid. What type of fuel do you use for the German engines in your simultions? Leichtbenzin, Flugbenzin or Fliegerbenzin if though which variant? Summer or winter variant as both had different mixtures of ethanol?

Edited February 5, 2023 by J99_Sizzlorr

[No.23_Starling]

Finally, an admission of a best guess. It’s your opinion based on fragmented facts. Experimentation at Aldershof does not equal widespread use from the start of 1918 and that’s a big leap of faith to make betraying a bias; if there’s a couple of German records talking to fuel mix usage by year, Jasta, and type then great, would love to read it, but it sounds like you want the Merc iiiau engines to get every boost they can regardless of evidence.

[J99_Sizzlorr]

6 hours ago, US103_Rummell said:

Finally, an admission of a best guess. It’s your opinion based on fragmented facts. Experimentation at Aldershof does not equal widespread use from the start of 1918 and that’s a big leap of faith to make betraying a bias; if there’s a couple of German records talking to fuel mix usage by year, Jasta, and type then great, would love to read it, but it sounds like you want the Merc iiiau engines to get every boost they can regardless of evidence.

I don't want anything. But I expect the Germans did exactly that in 1918 because they knew it will be over if the Kaiserschlacht fails and America comes in with more force. I just asked Holtzauge question. It seems you are afriad of it being acknowledged somehow for little chance that it plays any role in his simulations and for the little chance developers act upon his simulations. Aren't you overreacting. Things happened in history even if you haven't read anything about it or I lack primary sourcres about it. But there are sources out there I just don't have them at hand. That is no reason to not regard it if your aim is an exact simulation.

Edited February 6, 2023 by J99_Sizzlorr

[Holtzauge]

2 hours ago, J99_Sizzlorr said:

I say yes every high altitude engine probably used it from early 1918 onwards because they experimented with it at Adlershof. 

 

We don't know if his book will have any effect on FC, as it stands there is only a slight chance of that going to happen.

 

 

"I say yes every high altitude engine...Probably because they were experimenting at Adlerhof? Early 1918" 

 

Really? Every engine? At all Jastas? And when?

 

And thank you for your prediction about the chances my book has. Having written it, I at least know what it contains, and even I cannot make any predictions, so I'm duly impressed that you have this ability without even having read it.

 

2 hours ago, J99_Sizzlorr said:

I think the elaborate carburetor was designed before Fliegerbenzin was produced. The type was used as Germans had a shortage of fuel by the beginning of 1918. Adding Benzol streched their supplies so why wouldn't you do it?

 

"I think the elaborate carburetor was designed before Fliegerbenzin was produced...Adding Benzol streched their supplies so why wouldn't you do it?"  

 

A lot of supposition there wouldn't you say? Did they? Do we know? When?

 

2 hours ago, J99_Sizzlorr said:

Edit: I am also aware that pilot accounts  proof nothing, it just got me to digg into the different fuel variants because it irritated me when I read it that is why I brought it up here.

 

So how long did that engine survive after that treatment? Did Göring say anything about that? Was it worn out after a few flights? Do we know?

 

And after WW1 it is true that British ruined German engines in bench tests by running them outside specs to see what they could do: I got both the Mercedes D.IIIaü and BMW DIIIa British test reports from Bletchley. For the BMW they noted that that they ran hot and detonated. They did run a test with 50% Benzol added for an hour at 9/10th full power. Not ethanol. And after running the engine some more it failed.

 

I have also seen and read the info on this at The Aerodrome forum, including the “BMW IIIa @ 1400rpm” power charts you posted earlier. I’m assuming 209 hp up to a FTH of 2100 m in my simulations for reason I list in the book. You are welcome to give your input on that when you have read my motivations in the book.

 

During ww2, the Allison engine had a 42” 15 m rating and a takeoff rating of 51”. Reports then came to the attention of the engine manufacturer that pilots had been running them at 70” without them falling apart. So is this proof that we should have a 70” Allison in-game?

 

This type of argumentation has been going on for years in the forum, and I believe the developers way to handle it is that the engines in-game are implemented according to specs.  Across the board. So the Allison never got the 70” boost option. It operates according to the flight manual.

 

And the flight manual and the engine manufacturer recommendations for the Mercedes D.IIIaü and BMW DIIIa are I believe to operate the “Höhengas” as the name implies.

 

But I am interested in simulating what we have in game and what is historical. And if you manage to convince them and me with compelling proof that the Mercedes D.IIIaü and BMW DIIa operated with the altitude throttles bottomed out from SL up with no ill effects then that would be interesting.

 

2 hours ago, J99_Sizzlorr said:

My question still stands unsawered I am afraid. What type of fuel do you use for the German engines in your simultions? Leichtbenzin, Flugbenzin or Fliegerbenzin if though which variant? Summer or winter variant as both had different mixtures of ethanol?

 

Again: I assume a power output of 209 hp constant up to a full throttle height of 2100 m for the BMW DIIIa. And why I do that is explained in the book. So I'm actually even a bit more optimistic than Dechamps & Kutzbach.

 

The straight line with about 254 hp at SL was also what the British tested after the war with the results as I outlined above. The German did this when? At which Jasta?

 

And  please do tell how I should simulate and differentiate if the engine is running on summer or winter variants?: What are the power levels I should model under these conditions?: "Leichtbenzin, Flugbenzin or Fliegerbenzin if though which variant? Summer or winter variant as both had different mixtures of ethanol?"

 

Should I and Dechamps & Kutzbach change our numbers if we are assuming summer or winter fuel variant? Because Kutzbach just calls the fuels "Benzin" and Benzol"?

 

Are the Kutzbach figures using summer or winter variant?

 

What are the compositions of "Benzin" and Benzol" in Kutzbachs figures?

 

So many questions........

 

 

 

Edited February 5, 2023 by Holtzauge

[ZachariasX]

I think just sourced myself a copy of the Dechamps book for a very acceptable price. The problem is with those old books, especially when the price is really right and  you can't inspect them first with your own eyes, quality of the pages inside is sometimes a bit of a gamble. I hope that the parts that I (and we here) are interessted in the most are in passable condition.

 

If everything turns out well, I can share scans of the respective articles and we can take it from there. I doubt that there's still copyright on these articles. Fingers crossed.

[Holtzauge]

2 minutes ago, ZachariasX said:

I think just sourced myself a copy of the Dechamps book for a very acceptable price. The problem is with those old books, especially when the price is really right and  you can't inspect them first with your own eyes, quality of the pages inside is sometimes a bit of a gamble. I hope that the parts that I (and we here) are interessted in the most are in passable condition.

 

If everything turns out well, I can share scans of the respective articles and we can take it from there. I doubt that there's still copyright on these articles. Fingers crossed.

 

Now that will be interesting! Looking forward to it! 

[J99_Sizzlorr]

5 hours ago, Holtzauge said:

 

"I say yes every high altitude engine...Probably because they were experimenting at Adlerhof? Early 1918" 

 

Really? Every engine? At all Jastas? And when?

I don't know that but my guess is that the Germans didn't use the 100 train waggons of Fliegerbenzin they secured from Austria-Hungary out of Romania from the 1st of March 1918 to clean their windows. I know Rummell that I am probably biased in that assumption and it is pulled by the hair but it seems very unlikely they watered their plants with that as well. As can be read here: Sammlung der kreigswirtschaftlichen Vereinbarungen mit dem verbündeten Ausland Band 2; page 388.

 

Also Ludendorffs assesment comes to mind when he declares in the end of October 1918 that without Romania they will only have Fliegerbenzin for 2 more month. Which probably shows how important that resource was. Again just assumptions here and probably far fetched as well.

 

5 hours ago, Holtzauge said:

"And thank you for your prediction about the chances my book has. Having written it, I at least know what it contains, and even I cannot make any predictions, so I'm duly impressed that you have this ability without even having read it.

I just made a prediction of how big the chances are that the different fuels play a role in your simulation and how big the chances are the developers of this game will change anything based up on your simulations assuming different fuels play a role there, to show Rummell that it is not very likely that when I ask you a question about the fuel you used in your simulations that we will suddenly have high altitude engines running on the right fuel variation in the game. I didn't see any correlations there so no reason for him to try to shut me up all the time. I didn't say your book has little chance of being successfull. You got me wrong there. Infact I got interested in the different fuels for aviation used in WW1 and I just wanted to know if there is something in your book that might be of value to me.

 

5 hours ago, Holtzauge said:

So how long did that engine survive after that treatment? Did Göring say anything about that? Was it worn out after a few flights? Do we know?

Unfortunately I am in the dark about that the same as you are. Didn't really talk to Göring much, didn't like his attitude

 

5 hours ago, Holtzauge said:

And  please do tell how I should simulate and differentiate if the engine is running on summer or winter variants?: What are the power levels I should model under these conditions?: "Leichtbenzin, Flugbenzin or Fliegerbenzin if though which variant? Summer or winter variant as both had different mixtures of ethanol?"

I don't know what kind of variables are part of your simulations this is why I ask if different fuels are regarded or not. I am no engineer nor chemist I am just curious and try to understand things around me better. In this case it was the Göring anecdote. This is why I ask questions like can you fuel your simulation with different variations.

 

I only know how the variants were mixed together:

Summer Variant is estimated to be 40% German LT. Petrol (Leichtbenzin) and 60 % Summer Benzol (67.5% Benzene, 18% Toluene, 4,5% Xylenes and 10% Solvent Naphtat) this would lead to an octane number of 91.4

Winter variant is 50% German heavy petrol (Schwerbenzin) and 50% Winter Benzol (57.7% Benzene, 15,4 % Toluene, 3,9% Xylenes and 23% solvent Naphthat)

this would lead to an octane number of 78.2

I really don't know how this translates into the power levels. But my uneducated guess is that the BMW engine would gain 4.2bps per octane number given the values we get out of it on the wrong fuel and the right fuel.

Edited February 6, 2023 by J99_Sizzlorr

[ZachariasX]

8 hours ago, J99_Sizzlorr said:

I only know how the variants were mixed together:

Summer Variant is estimated to be 40% German LT. Petrol (Leichtbenzin) and 60 % Summer Benzol (67.5% Benzene, 18% Toluene, 4,5% Xylenes and 10% Solvent Naphtat) this would lead to an octane number of 91.4

Winter variant is 50% German heavy petrol (Schwerbenzin) and 50% Winter Benzol (57.7% Benzene, 15,4 % Toluene, 3,9% Xylenes and 23% solvent Naphthat)

this would lead to an octane number of 78.2

 

Why is the winter grade a heavyier fuel than the summer grade? As far as I know it is typically (like on your local gas station) the other way around to compensate for reduced evaporation in cold weather.

[Holtzauge]

9 hours ago, J99_Sizzlorr said:

I don't know that but my guess is that the Germans didn't use the 100 train waggons of Fliegerbenzin they secured from Austria-Hungary out of Romania from the 1st of March 1918 to clean their windows. I know Rummell that I am probably biased in that assumption and it is pulled by the hair but it seems very unlikely they watered their plants with that as well. As can be read here: Sammlung der kreigswirtschaftlichen Vereinbarungen mit dem verbündeten Ausland Band 2; page 388.

 

Also Ludendorffs assesment comes to mind when he declares in the end of October 1918 that without Romania they will only have Fliegerbenzin for 2 more month. Which probably shows how important that resource was. Again just assumptions here and probably far fetched as well.

 

OK, so Fliegerbenzin now harks from the Romanian oilfields? So is it the straight run fuel extracted from the crude? If so I doubt it is better than 72 in octane rating from the Shell Sumatra which was the best on the Allied side. But I would have thought that that was Leichtbenzin not Fliegerbenzin? I thought Fliegerbenzin was the stuff mixed up with Benzol? Or did they do that already at the Romanian oil fields?

 

9 hours ago, J99_Sizzlorr said:

I just made a prediction of how big the chances are that the different fuels play a role in your simulation and how big the chances are the developers of this game will change anything based up on your simulations assuming different fuels play a role there, to show Rummell that it is not very likely that when I ask you a question about the fuel you used in your simulations that we will suddenly have high altitude engines running on the right fuel variation in the game. I didn't see any correlations there so no reason for him to try to shut me up all the time. I didn't say your book has little chance of being successfull. You got me wrong there. Infact I got interested in the different fuels for aviation used in WW1 and I just wanted to know if there is something in your book that might be of value to me.

 

Well if my book will be of any use to you depends on what you are looking for: If you are interested in how these aircraft performed based on assumptions about what power levels the engines produced then you may find it interesting. But if you want to go chasing down the rabbit hole looking at the percentage compositions of different fuels, how many wagonloads were transported where, and if field modifications were done on Jasta level to factory delivered aircraft to allow them to run with full throttle from SL up, then I don’t have that info in the book.

 

9 hours ago, J99_Sizzlorr said:

Unfortunately I am in the dark about that the same as you are. Didn't really talk to Göring much, didn't like his attitude

 

OK, good that we seem to agree that pilot anecdotes about running engines way outside operating limits are not to be taken as proof that this should be taken into account either in simulations nor implemented in-game.

 

9 hours ago, J99_Sizzlorr said:

I don't know what kind of variables are part of your simulations this is why I ask if different fuels are regarded or not. I am no engineer nor chemist I am just curious and try to understand things around me better. In this case it was the Göring anecdote. This is why I ask questions like can you fuel your simulation with different variations.

 

I only know how the variants were mixed together:

Summer Variant is estimated to be 40% German LT. Petrol (Leichtbenzin) and 60 % Summer Benzol (67.5% Benzene, 18% Toluene, 4,5% Xylenes and 10% Solvent Naphtat) this would lead to an octane number of 91.4

Winter variant is 50% German heavy petrol (Schwerbenzin) and 50% Winter Benzol (57.7% Benzene, 15,4 % Toluene, 3,9% Xylenes and 23% solvent Naphthat)

this would lead to an octane number of 78.2

I really don't know how this translates into the power levels. But my uneducated guess is that the BMW engine would gain 4.2bps per octane number given the values we get out of it on the wrong fuel and the right fuel.

 

Repeating exact percentage fraction of different fuels is not very helpful. Neither is listing fractions of percentages on octane levels. The engines used in WW1 were not rocket science and were probably not that picky about fuels as long as the fuel ratio was right and the engine did not detonate.  So I would be very surprised if there was a very large power output difference between the different fuels at a certain compression ratio when tuned right: The Mercedes D.IIIaü had a special carburetor fitted that simply did not allow full throttle at lower altitudes. On the British tests when they extracted full power at SL with it, they fitted a standard D.IIIa carburetor to it. So if you want to see this implemented in-game you need to convince the developers that this was done by the mechanics on Jasta level, i.e. they got deliveries of Albatros D.Va’s with the proper high altitude carburetors, but since they now had abundant supplies of 90 octane Fliegerbenzin, they removed these carburetors and fitted new ones (was that the old D.IIIa carburetos perhaps?). Or, was it so, that by “early 1918” the usage of 90 octane Fliegerbenzin was now so widespread that deliveries of new Albatros D.Va’s were now done with the “old” D.IIIa carburetor that allowed the pedal to the metal from SL up?

 

However, this of course begs the question of why in late 1918, did the British then still test the Mercedes D.IIIaü engine with the special high altitude carburetor? The one that did not allow full power at SL? Maybe they were unaware that the Germans already from “early 1918” had been operating them with 90 octane fuel sans the high altitude carburetors? 

 

 

[ST_Catchov]

I dunno? I'd like to hear from @Cynic_Al about this. It's gettin' a bit too much for me.

[J99_Sizzlorr]

4 hours ago, Holtzauge said:

OK, so Fliegerbenzin now harks from the Romanian oilfields? So is it the straight run fuel extracted from the crude? If so I doubt it is better than 72 in octane rating from the Shell Sumatra which was the best on the Allied side. But I would have thought that that was Leichtbenzin not Fliegerbenzin? I thought Fliegerbenzin was the stuff mixed up with Benzol? Or did they do that already at the Romanian oil fields?

No but you need crude oil to manufacture it. As far as I understand it the crude oil came from Romania but Austro-Hungary had to manufacture the Fliegerbenzin and deliver it to Germany. Just read the source I quoted.

 

4 hours ago, Holtzauge said:

Well if my book will be of any use to you depends on what you are looking for: If you are interested in how these aircraft performed based on assumptions about what power levels the engines produced then you may find it interesting. But if you want to go chasing down the rabbit hole looking at the percentage compositions of different fuels, how many wagonloads were transported where, and if field modifications were done on Jasta level to factory delivered aircraft to allow them to run with full throttle from SL up, then I don’t have that info in the book.

Just could have said this earlier that your simulation doesn't take other fuels into account.

 

4 hours ago, Holtzauge said:

OK, good that we seem to agree that pilot anecdotes about running engines way outside operating limits are not to be taken as proof that this should be taken into account either in simulations nor implemented in-game.

As I said earlier, this anecdote just irritated me, and I try to understand where this comes from. It is not proof of anything but the culprit why I was looking into different fuels  that might explain this letter.

 

4 hours ago, Holtzauge said:

Repeating exact percentage fraction of different fuels is not very helpful. Neither is listing fractions of percentages on octane levels.

Then don't ask for it.

 

4 hours ago, Holtzauge said:

The Mercedes D.IIIaü had a special carburetor fitted that simply did not allow full throttle at lower altitudes. On the British tests when they extracted full power at SL with it, they fitted a standard D.IIIa carburetor to it. So if you want to see this implemented in-game you need to convince the developers that this was done by the mechanics on Jasta level, i.e. they got deliveries of Albatros D.Va’s with the proper high altitude carburetors, but since they now had abundant supplies of 90 octane Fliegerbenzin, they removed these carburetors and fitted new ones (was that the old D.IIIa carburetos perhaps?). Or, was it so, that by “early 1918” the usage of 90 octane Fliegerbenzin was now so widespread that deliveries of new Albatros D.Va’s were now done with the “old” D.IIIa carburetor that allowed the pedal to the metal from SL up?

 

I don't think they changed the carburetor but they set it differently. They have an H-setting and a V-setting and they can tune in between as I understand. If you look at the graph from Mercedes Werke Stuttgart you see the different settings of the carburateor they are called "Stellung des Vergasers" in German and you can see the H-Stellung and the V-Stellung. I really don't understand how these carburetors work I mean I know what they do but don't know how. Anyway I can see that they did something different with it depending on what fuel was used or what altitude it was set for.

 

Edited February 6, 2023 by J99_Sizzlorr

[ZachariasX]

31 minutes ago, J99_Sizzlorr said:

I don't think they changed the carburetor but they set it differently. They have an H-setting and a V-setting and they can tune in between as I understand.

That AFAIK done with the throttle. The throttle lever could be walked forward to the "V" mark that indicated "Vollgas" (full  power) and then beyond that to the end of the travel where the "H" Mark was, "Höhengas". That is where the letters come from and reflect from when on the engine uses Höhengas. The position from when the engine reached full Höhengas is marked on the powe curve.

 

Also it is of note that in contrast to the BMW engine, the Daimler has specific arrangement to actually (try to) keep mixture ratio constant with decreasing athmospheric pressure. It has a special kind of air valve for that. This means it runs richer on average than the very lean running BMW.

 

I copied text from the engine manual, emphasis mine:

 

Inspektion der Fliegertruppen
Nr. 3131/7.18 Flz. B

Charlottenburg 5, den 11. Juli. 1918

Behandlungsanleitung!
für den überkomprimierten D.III und D.IIIa Motor.
(160 PS. Mercedes.)

1.) Die Überkompression ist erreicht durch Einbau gewölbter, anstelle gehöhlter Kolben. Äußerlich sind die Motoren kenntlich durch je einen roten Ring um die Cylinder.

Außerdem ist der Vergaser dahingehend geändert, dass das Mischungverhältnis in jeder Höhe möglichst konstant bleibt, was durch teilweise Steuerung des Zusatzluftringes erreicht wurde.

Der Drosselhebel am Vergaser ist mit einer Markierung versehen, welche die Buchstaben "V" (Vollgas) und "H" (Höhengas) trägt.

2.) Die ersten aus der Fabrik gekommenen Motoren sind meistens in der Hauptdüse etwas zu sparsam einreguliert. Bei richtig gewählter Düse muss die Drehzahl bei voller Öffnung des Vergasers auf Höhengas im Stand um 50 Touren zurückgehen, was außerdem den Vorteil hat, dass der Motor im Stand nicht überbeansprucht werden kann. Dies ist zu - gleich eine Kontrolle für die richtig gewählte Vergaser - einstellung.

3.) Im Fluge darf über die V - Stellung erst über 2000 m Flughöhe hinaus gegangen werden, in der Weise, dass stets nur so weit geöffnet wird, daß die Drehzahl konstant bleibt. Bei zu früher völliger Öffnung auf Höhengas (unter 3000 m) fällt die Tourenzahl ab. Soll nicht nach dem Touren-zähle reguliert werden, so empfiehlt sich erst ab 3000m Flughöhe auf Höhengas voll zu öffen. Bei dieser groben Regulierung können jedoch kleine Leistungsunterschiede durch die Wetterlage bedingt werden.

4.) Die durch Überkompression und Vergaserveränderung gewonnene Leistungszunahme zeigt sich, wenn man in 4 - 5000 m Höhe den Vergaser auf V - Stellung zurückdrosselt und wieder auf H - Stellung öffnet.
Die hierbei sich ergebende Tourenzunahme zeigt den Leistungsunterschied zwischen normalen und überkomprimierten Motoren.

5.) Für überkomprimierte Stand - Motoren kommen grund - sätzlich nur 2 polige Zündkerzen mit abgerundeter Mittel - Elektrode in Betracht.

gez. Unterschrift

Firma

Daimler-Motoren-Gesellschaft
Stuttgart=Untertürkeim

2 Anlagen.

Moba Daimler

 

You can see that the pilot has no way to change the mixture. Daimler obviously was very keen about people not abusing their engines. Hence the leaning of the mixture when unduly engaging Höhengas. The whole carb only works at intended power levels. It is specifically made to choke on someone just firewalling the throttle, to keep the pilot from having to walk home. They specifically instruct the pilot to walk the throttle forward in accordance to rpm drop during climb. If he's too nervous for that, then by all means he better be above 3000 m.

 

What we have with the aü Daimlers are engines that give you identical performance to the normal compressed engine down low. Above 2000 m you are allowed to get tap the extra power of the higher compression by walking the stick further forward. Doing that below 2000 meters, the Daimler will chocke slightly and drop power.

 

In this sense, I find it questionable to conclude that there was a lot of effort to source high octane fuels, as the average stuff on either side of the front lets all engines perform according to specs. Diluting fuel with Ethanol might help you in cold winter, but as the fuel is lighter, your mileage gets reduced. Benzol is an issue as it is a mess to handle, eats your rubber fittings and tubing and forms raisin in the cans. It's really, really hard to beat isooctane in feeding Otto engines.

[J99_Sizzlorr]

That is my assumption that they used the Höhengas differently on different fuels because higher octane fuel enabled them to do it. They could reach the H-Stellung earlier with Benzol added to the fuel.

 

That they used Benzol in their fuel variants I think is out of question, I mean there are several tests done with it on both the BMW and the Mercedes aü engine. There was a big ammount of it delivered by the Austrians and German high command was concerned of it running out. It is not a big leap to conclude they used it on the frontline as well. But to what effect is what I am looking for. And can it explain Görings letter?

It sure had its drawbacks like eating through rubber, therfore you have to clean those parts more frequently and degrading engines faster but getting every last bit of power out of the Mercedes engine was what the Germans did throughout the entire war. Why do you think they didn't use higher octane fuels even if it was available to them and they knew they would get better performance out of it and stretch their fuel supplies which were low by the time at the same time in a war that they are about to lose anyway if they don't succeed with their spring offensives is what I don't understand.

I am also sure the mixture of the Mercedes engine could be adjusted not by the pilot but by ground crews.

Edited February 6, 2023 by J99_Sizzlorr

[ZachariasX]

1 minute ago, J99_Sizzlorr said:

And can it explain Görings letter?

In principle, I do think Göring might have told "the truth" in what is maybe bit of a jovial manner. The BMW does work in a way that you get extra hp down low. How much power you actually did get, he had no way of knowing. By that time in war, Goering did so little airime that flying around with a clicking engine probably wouldn't really make it noticed in the availability of an aircraft to him. Same as when getting chased by SPADs, a clicking engine is the least of your worries, especially when it gives you the edge, at least momentarily. Thing is, those engines had (and still have) abysmal TBO anyway, hence when performed ocasionally, those burned pistons probably didn't stand out in the maintenance reports as they would today. Still, none of all that justifies abusing the engine when there is no fundamental requirement to it, because by doing so, you're actively fighting for the other team.

 

There is no question about them using benzol, it is certain that they did. What I tried to say is that lacing fuel with any such additives comes at a price and the means should be worth the ends. Benzol as a mean that you can actually have aircraft flying is one thing. More benzol for that they can mostly fly in ways that are not relevant to the war effort is a different thing. The more you benzol you put in, the messier the fuel gets.

 

If I stay with the rationale that benzol was a way to have acceptable fuel, then it makes sense to make moderate use of it, especially since the engines were designed in a way to deal with the given fuel. I assume this was the case rather than the rationale of having fuel and lacing it with benzol to a degree to have racing fuel. That winter and summer blends have a different knock resistance tells me that on average they were happy with what they had in general and stuff worked as intended.

 

Racing fuel doesn't give you more power per se than average fuel, but it allows you to set the engine differently, give it more compression or have it run even richer in the rich-rich regime at full power to get the extra power, none of which are documented. This means, I would be looking for documented change in engine setup (even somewhere in the field) if the operator is certain that his fuel is now a gamechanger and engines should adapt. But I have not seen any of that. Hence, I'd say the manual still applies. Also, internal load increase kills the engine as well. At some point the bearings and struchture give in. None of these engines achieve even remotely what are acceptable TBO today. I assume additional strain on it would certainly make it felt on a squadron level. And none oft his rules out that the individual pilot was doing it anyway at some point. At least with the BMW.

[J99_Sizzlorr]

Mechanic: Hey how is the war going?

 

Pilot: Pretty stiff you know, I heard that we are going on the offensive again for the Kaiser as a last effort.

 

Mechanic: Uh.. sounds rough. How was flying today?

 

Pilot: Well I nearly got a Spad but he then dived to the deck and escaped me, because I couldn't follow.

 

Mechanic: Yeah that's a bummer.

 

Pilot: You know I heard there are 100 waggons of that racing fuel called "Fliersfuel" (Fliegerbenzin) with higher octane that would enable me to use the Höhengas even lower than advised in the manual because it has higher combustion resistance, which Austria-Hungary had to deliver to us for the sacking of Romania. It is just sitting in Ludendorffs garden and he is watering his plants with it and cleaning his windows and has no other appearant use. Do you think you could fuel up my Fokker with it so that I can get that Spad tomorrow?

 

Mechanic: Nah, I heard it eats through rubber faster and then I have to clean your engine more often. I don't think this is going to happen. You know my back hurts and all that stuff.

 

Pilot: Yeah you are probably right. Hey do you want to have a beer with schnapps? I heard it enhances your toxication.

 

Mechanic: Sure why not!

Edited February 6, 2023 by J99_Sizzlorr

[J99_Sizzlorr]

Interesting article by Bletchley

 

Quote

 

Central Powers, 'Making a little go a long way ?'

 

At the otbreak of war in 1914 Austria-Hungary was producing 890, 000 tons of crude oil a year, or 1.6% or world production - 875,000 tons of which was from a large number of small producers in Galicia. Of this 400,000 tons was exported, over 50% of it to Germany. Germany produced only 110,000 tons from within its own borders, 0.2% of world production - ten times as much as France (10,000 tons), but less than half as much as Britain (290,000 tons, mostly from Scottish shale). With stocks of only 340,000 tons (around 85,000 tons of this in the form of gasoline and lubricants, 50,000 tons of which was allocated as aviation fuel), and consumption running at 1,400,000 tons per year in 1914, Germany (even with Galician oil from Austria-Hungary) was not prepared for a long war of industrial attrition. Germany required a further one million tons of oil a year, from other countries through or around the Allied blockade, just to maintain pre-war levels of consumption. Of this, between 127,00 and 155,000 tons a year were being imported from Romania up to the middle of 1916. This still left a huge shortfall in the early to mid part of the war, particularly when the Galician oilfields were briefly occupied by the Russian army (Galician consumption fell to 677,000 tons in 1915, recovering to 928,000 in 1916 but declining thereafter to 900,000 tons in 1917, and then 840,000 tons in 1918), whilst the crude oil from Romanian oil fields was also blocked briefly when Serbia closed the Danube to oil barges in 1914. Most of this oil was for domestic lighting and heating and for industrial use, but the Army was consuming around 25% of all gasoline imported into the country. Gasoline for both the army and an expanding air force was an immediate priority, and in the early spring of 1915 very severe restrictions were imposed. on private motorists, including on order from the Bundesrat on March 15th 1915 to take 25,000 automobiles off the roads.

 

Despite this shortfall in the supply of crude oil, there is nevertheless little evidence that the German army or air force went short of fuel in this first period of the war, up to the spring of 1917. Domestic restrictions, and the use of alternative fuels in the form of benzol petrol or of benzol petrol alcohol mixtures in motor vehicles, ensured that the lighter gasoline fractions in particular, from the German refineries, could be diverted to meet the expanding needs of the air force. At the outbreak of war Germany, unlike France, had some extremely good oil refineries, probably amongst the best at that time in Europe, if not the world, and was quite capable of taking any crude oil from any source to refine and blend into fuels that could match the Entente's straight run gasoline fractions from the East Indies. In the early years of the war, however, with access to good quality light crude from Romania, and with existing pre-war stocks to draw from, the German refineries appear to have been producing just two basic grades of gasoline for aviation use - a 'Leichtbenzin' or 'light gasoline', a close cut distillation with a specific gravity of 0.68 - 0.70 and distillation range: 20% by 60 deg. C, 60% by 80 deg. C, approx. 98% by 100 deg. C (final, 115 deg. C); and a 'Schwerbenzin' or 'heavy gasoline', another close cut distillation but with a specific gravity of 0.70 - 0.75 and a distillation range: 10% by 100 deg. C, 40% by 120 deg. C, 60% by 130 deg. C, 80% by 140 deg. C, 90% by 150 deg. C (final 170 deg. C) (Reinhardt). The Leichtbenzin appears to have been reserved for front-line units and aircraft industry, whilst the heavier 'Schwerbenzin' appears to have been allocated to training and home defence (AchimEngels). Although apparently low in aromatic content, this Leichtbenzin would have supported most of the low compression aero engines then in use without much danger of detonation.

 

By the spring of 1915, therefore, reports filtering through to the Allies indicate that, despite the blockade, there was little sign of fuel shortages amongst German military units on the Western Front, either on the ground or in the air. United States neutrality at this time meant that the US reporters and diplomats in Germany were in a good position to feedback information on the situation in Germany, and in an interview between Lord Kitchener and Irvin S Cobb, published in a London newspaper and reported in the New York Times on 10th January 1915, Kitchener asked Cobb: "Is there any shortage of the supply of available petrol in the field ?" Cobb replied that "there is no actual shortage of fuel, as distinct from petrol" as "the Germans have been using large quantities of a benzine product... commonly known as benzol" The report goes on to add that "More light is daily being shed on the subject through the examination of captured or destroyed transports. To eke out their petrol supplies German military cars and wagons are making considerable use of a benzol-alcohol mixture" in such quantities that, according to other reports, "except for her aerial fleet, Germany could almost dispense with petrol, and still continue her warlike activities", as German industry was able to "manufacture all the benzol and alcohol neccessary for the military motors." This, the report states, at least in part: "solves the problem which has been baffling many on this side: Where is Germany getting her fuel from ?" ("Germany using substitute fuel"). Between the spring of 1915 and the summer of 1916 there were similar press reports, confirming in detail that Germany was using a variety of heavy gasoline-benzol and benzol-gasoline-alcohol or benzol-alcohol mixtures both domestically and on the ground at the Front to substitue for gasoline ("25,000 Berlin autos stop", "Use gasoline mixture", "Tells Germany;s motor mixture"). There is no indication, however, from any of these reports that benzol or alcohol mixtures, with or without gasoline, were being used before the end of 1916 in aviation fuel.

 

Benzole is not the same as benzene, although benzene is the main constituent of benzol. A typical refined benzol (or benzole) of this period, suitable for use as a fuel, typically had a 90% aromatic content (and so was sometimes referred to as "90s benzole", the remaining 10% being heavy gasoline or kerosene, and the aromatic content was about 75% benzene, 20% toluene and 5% xylenes (Hoffert). The ratio of constituents could vary, though, and the aromatic content of the German refined benzole used in fuel mixtures has been listed as 84% benzene, 13% toluene and 3% xylenes (Reinhardt). By 1910 Germany was using half of German benzol production, a byproduct from coke ovens and gas works, for motor fuel and the German producers had joined together in the 'Westdeutsche-Benzol-Verkaufsvereinigung' (later it was renamed the Benzol-Verband, still exists today as Aral AG & Co.), and formed a distribution network for motor benzol in Germany, even importing large quantities from Britain and the US. By 1913 it was receiving government support, with a new state-funded benzol plant producing 6 million gallons a year on goverment property, and even royal sponsorship in the form of Prince Henry of Prussia (Miller). But as benzol production was closely linked to the coking industry, it was relatively inelastic and could not be increased dramatically between 1914 and 1918, so total production in Germany rose from a pre-war level of 230,000 tons in 1913 to only 248,000 tons in 1918 (Friedensburg) - this was, however, much greater than the output in any other European country or the USA, and made a huge contribution to filling the gap left by the reduction in gasoline supplies from foreign oil imports. But even though it was known before the outbreak of war in 1914 that benzole could be used on its own, or in a mixture with either gasoline or alcohol (or in a combination of all three) to suppress the 'knocking' in petrol engines, and would support a higher compression ratio than any gasoline used on its own, it was also 'heavy' with a very high specific gravity of 0.87 to 0.885 and a slightly lower calorific value than gasoline. When used as an aviation fuel, benzole also had the severe disadvantage of a very high freezing point - when used on its own, it will start to freeze at +3 deg. C, and even in a mixture with gasoline it can raise the fuel's freezing point from the -50 to -55 deg. C of a gasoline to a figure as high as -20 deg. C or more, although the freezing point will depend on the proportion of benzol to gasoline and on the toluene content of the benzol, so that a fuel with a 20% or less of benzole content, or with an increased proportion of toluene, could nevertheless meet even a specification for fuels such as the British postwar DTD 224 Specification with the requirement that it would not freeze above -50 deg. C (Hoffert).

 

But something happened in August 1916 that changed everything - Romania entered the war on the Allied side, attacking Austro-Hungarian forces in Transylvania, and suddenly Germany (and Austria-Hungary) no longer had access to the light crude oil from the Romanian oilfields. German forces counter-attacked, and by mid November 1916 had captured the Romanian oilfields. Before they arrived, however, the Romanian engineers - with the urging and assistance of the British military mission to Romania, had comprehensively destroyed all of the above-ground stocks of petroleum and most of the equipment, pipelines, tanks, refineries and installations. It took the German engineers about six months to get the oil flowing again, leading to a hiatus in supply that lasted through until mid to late 1917. Total Romanian oil production dropped from 1,673,000 tons in 1915 to 1,244,000 tons in 1916, and then to just 517,000 tons in 1917. By the spring and summer of 1918, however, it was back up to 1916 levels at 1,214,000 tons, the bulk of which, 890,000 tons, was being sent to Germany with 231,000 tons to Austria-Hungary, 13,800 tons to Turkey and 5,900 tons to Bulgaria (Friedensburg). Between the autumn of 1916 and the end of 1917, however, the German refineries had to rely largely on their remaining stocks of the Romanian oil and the dwindling supply of somewhat heavier Galician oil. This was a severe blow to the German and Austro-Hungarian air forces as, up to this time, they appear to have been getting sufficient supplies of light gasoline to meet most of their front-line requirements, but now faced imminent shortages from the spring of 1917 when air activity would increase. A decision appears to have been made at this time to produce a new blended aviation fuel (possibly just for two-seater units, to start with), a 'Mittelbenzin' or 'Flugbenzin' that was not a straight-run distillate, but a blend of approximately 60% 'Leichtbenzin' and 40% 'Schwerbenzin' from a variety of sources (Reinhardt). The chemical composition of this blend, according to the analysis of two captured samples of this fuel by the French in the summer of 1917 (Dickinson), was very similar to that of the Shell East India gasolines and had, very strikingly, a relatively high aromatic similar to that of Sumatra and Borneo. It is known that the Germans had access to the Shell East India gasolines before the war, they had analysed the content of these fuels and were aware of their relatively high aromatic content (Reinhardt). It seems likely, therefore, that they were using these as 'reference fuels' in the creation of the blended 'Flugbenzin', and as neither Galician nor Romanian oil was noted for its high aromatic content (Hoffert), it seems probable that, from the winter of 1916, at least, they were adding some benzol to the blend to achieve a very similar aromatic content. This would help to explain the remarkable similarity in the chemical composition and distillation properties of the Flugbenzin and East India gasolines, noted by the French and the Americans. In Ricardo's immediate post-war analysis of the chemical and anti-knock properties of the gasolines then in use, one 'reference fuel' (E) stands out as a close match to the Reinhardt's distillation curve and the German Flugbenzin samples analysed by the French in 1917. This is listed with a specific gravity of 0.719: 68% paraffins, 11.3% aromatics, 20% naphthenes, and a 'highest useful compression ratio of 4.7:1, and is a close match to the chemical composition of the two different samples of Flugbenzin captured and analysed by the French: 68-78% methanes, 24-26% naphthenes, and 7-8% aromatics. As Flugbenzin was a blend of several very different gasolines, it is not surprising to find some variation, even between the French samples, and the resulting blends probably varied somewhat in their capacity to resist detonation - but appear to have been generally lower in this respect than the Allied Sumatra gasoline, at 4.7:1 according to Ricardo's analysis of Highest Useful Compression Ratio, or between 4 and 5 to 1 according to AchimEngels' source. It is notable that very few of the German aero engines of this early to mid period had a compression ratio higher than 4.7:1 (KACEY).

 

Despite the introduction of Flugbenzin, which appears to have largely replaced Leichtbenzin as the main aviation fuel by the end of 1917, this period between the winter of 1916 and the spring of 1918 was a difficult one for the Germans, as it coincided with a big increase in the front-line aircraft strength from 2,270 aircraft in the spring of 1917 to 3,600 aircraft in the spring of 1918 - but a corresponding fall from 11,000 tons of fuel a month from early 1917 to 7,000 tons a month at the time of the Spring Offensive in 1918. The response to this was to make even greater use of the benzol still available in very large quantities, and experiments with a variety of petrol-benzol and petrol-benzol-alcohol at Adlershoff and elsewhere led to the creation of a new petrol-benzol aviation fuel named 'Fliegerbenzin', in both a summer and a winter variety, that made use of this benzol. The summer variety was a mixture of 40% 'Leichtbenzin' and 60% benzol, and with a relatively high freezing point of -20 to -24 deg. C it was clearly not going to be suitable for the increasing altitudes at which air operations were being conducted by the German fighter and high-flying recon aircraft during the winter months. The 'winter benzin' that replaced this for the colder winter months was a 50/50 mixture of 'winter benzol' (77% benzol, 23% solentnaphtha) and 'Schwerebenzin', with a reduced aromatic content (to around 35%) that reduced the freezing point and allowed for high-altitude winter flying (Reinhardt; also Dechamps & Kutzbach). For home defence, a benzin benzol alcohol Spiritus-Benzol-Mischung was developed (Rammjaeger; also Dechamps & Kutzbach). Although the initial urgency to find these gasoline substitues was almost certainly generated by the developing fuel crisis of 1917, the introduction of benzolated fuel in increasing quantities and a gradually increasing aromatic contentalso enabled engine designers to increase compression ratios, cautiously at first in the spring and summer of 1917 (increasing the compression ratio of the Daimler Mercedes D.IIIa, for example), and then more dramatically from the winter/spring of 1917/1918 with some innovative 'Hohenmotoren' such as the BMW IIIa. British tests indicate that these very high compression late-war engines appear to have required the new Fliegerbenzin to support their very high compression ratios, but between them and the early to mid-war lower compression engine types there appear to have been a wide range of hybrid intermediate types, such as the overcompressed Mercedes and Benz, or the Maybach Mb.IVa, that seem to have functioned well on either Flugbenzin or Fliegerbenzin. According to British tests of a captured Maybach Mb.IVa, for example, this engine could be used as a high-powered low altitude engine when running on a rich mixture setting - but it could also function very well as one of the new Hohenmotoren when it was run, as intended, on a weak mixture of Fliegerbenzin in the high altitude recon aircraft or airships. Similarly, tests of the Daimler Mercedes D.IIIau by the British indicated that, when run on a Sumatra gasoline (or on a similar Flugbenzin) the engine would run well at low altitude or ground level when it was throttled back to 160 hp at 1400 rpm, but when unthrottled to 1500-1600 rpm (well within the mechanical limits of this engine) it appeared to loose power, probably from detonation (Piston aero engines of the Great War). German pilots, however, appear to have got 180 PS at ground level from this engine, presumably using the higher rpm range with non-detonating Fliegerbenzin, although it was still officially rated at 160 PS at 1400 rpm.

 

This was happening at a time, in the spring and summer of 1918, when supplies of light oil from Romania were arriving in great quantity, and there should have been no shortage of lighter Leichtbenzin coming out of German refineries from the spring of 1918 onwards. Despite this, the fuel shortage appears to have got worse. By June 1918 gasoline supplies to front-line units had fallen from 7,000 tons a month in 1917 to 5,000 tons a month in 1918, whilst their aviation fuel consumption had apparently risen from 7,000 tons to 9,000 tons a month in 1918 (a shortfall, presumably, being met by supplies of Fliegerbenzin), and restrictions were being placed on the number of sorties that could be flown from German airfields. It is likely that these shortages were not due to any real shortfall in the supply of a suitably light crude oil to German refineries - as Romanian oil was once again flowing into Germany and Austria-Hungary, and in much greater quantities than ever before - but to an increase in demand at the front combined with severe distribution difficulties on the home front, due to lack of spare parts and other industrial resources, disruption caused by civil disturbance and Allied strategic bombing, and the difficulties presented by the movement of fuel forwards from these refineries and rear areas to the front line units, particularly under the almost continuous low-level Allied bombing and strafing of German lines of communication from the spring of 1918 through to the end of the war.

 

Bletchley

 

References

 

'25,000 Berlin autos stop: government cuts down the use of gasoline and rubber', New York Times, 31st March 1915.

 

'Germany's new problems: substitutes for rubber and gasoline found perpexling', New York Times, 27th December 1914.

 

'Tells Germany's motor mixture: proportions in alcohol-benzol combustible used as economy substitute for gasoline', New York Times, 6th August 1916.

 

'Germans using substitute fuel: employment of benzol and alcohol may increase life of war motors', New York Times, 10th January 1915.

 

'Use gasoline mixture: Germans overcome shortage of fuel for motor vehicles', New York Times, 15th July 1916.

 

Brewer, Robert W. The motor car: a practical manual for the use of students and motor car owners. 1909.

 

AchimEngels. Aerodrome Forum, 29th July 2002.

 

Dechamps, H. and Kutzbach, K. Prufung, Werung und Weiterentwicklung von Flugmotoren. Richard Carl Schmidt, 1921.

 

Dickinson, H.C. (and others). 'Power characteristics of fuels for aircraft engines', NACA Report no.47.

 

Friedensburg, Ferdinand. Das Erdol im Weltkrieg. Enke, 1939.

 

Hoffert, W.H and Claxton, C. Motor Benzole: its production and use. The National Benzole Association, 1938.

 

Howarth, Stephen. A century in oil: the "Shell" Transport and Trading Company, 1897-1997. Weidenfeld & Nicolson, 1997.

 

Jonker, Joost and Luiten van Zanden, Jan. A history of Royal Dutch Shell, vol.1: from challenge to joint industry leader, 1890-1939. Oxford University Press, 2007.

 

KACEY. Aerodrome Forum.

 

Miller, J.C. Popular Mechanics, February 1913.

 

Piston aero-engines of the Great War. Hampshire County Library, 2009 (2 CD).

 

Rammjaeger. Aerodrome Forum, 3rd May 2003.

 

Reinhardt, Bruno. Vergaser, Brennstoffe und Brennstoffzufurung (Flugtechnische Bibliothek, Band 9), Richard Carl Schmidt, 1919.

 

Ricardo, H.R. 'The influence of various fuels on the performance of internal combustion engines: an experimental investigation into their behaviour', in The Automobile Engineer. (Part 1, February 1921, pp.51-54; Part 2, March 1921, pp.92-97; Part 3, April 1921, pp.130-133; Part 4, May 1921; Part 5, June 1921, pp.201-205; Part 6, July 1921, pp.242-247).

 

Riedler, A. 'Disturbing effect of free hydrogen on fuel combustion in internal combustion engines', Technische Berichte vol.III no.2, pp.25-26, 1918 (translated in NACA Technical Notes no.133, March 1923).

 

Bletchley

 

 

What stands out is: 

 

Quote

German pilots, however, appear to have got 180 PS at ground level from this engine, presumably using the higher rpm range with non-detonating Fliegerbenzin, although it was still officially rated at 160 PS at 1400 rpm.

 

Along with some more interesting books on the subject he used: 

Reinhardt, Bruno. Vergaser, Brennstoffe und Brennstoffzufurung (Flugtechnische Bibliothek, Band 9), Richard Carl Schmidt, 1919.

 

Dickinson, H.C. (and others). 'Power characteristics of fuels for aircraft engines', NACA Report no.47.

 

Ricardo, H.R. 'The influence of various fuels on the performance of internal combustion engines: an experimental investigation into their behaviour', in The Automobile Engineer. (Part 1, February 1921, pp.51-54; Part 2, March 1921, pp.92-97; Part 3, April 1921, pp.130-133; Part 4, May 1921; Part 5, June 1921, pp.201-205; Part 6, July 1921, pp.242-247).

Edited February 7, 2023 by J99_Sizzlorr

[No.23_Starling]

2 hours ago, J99_Sizzlorr said:

Mechanic: Hey how is the war going?

 

Pilot: Pretty stiff you know, I heard that we are going on the offensive again for the Kaiser as a last effort.

 

Mechanic: Uh.. sounds rough. How was flying today?

 

Pilot: Well I nearly got a Spad but he then dived to the deck and escaped me, because I couldn't follow.

 

Mechanic: Yeah that's a bummer.

 

Pilot: You know I heard there are 100 waggons of that fuel called "Fliersfuel" (Fliegerbenzin) with higher octane that would enable me to use the Höhengas even lower than advised in the manual because it has higher combustion resistance, which Austria-Hungary had to deliver to us for the sacking of Romania. It is just sitting in Ludendorffs garden and he is watering his plants with it and cleaning his windows and has no other appearant use. Do you think you could fuel up my Fokker with it so that I can get that Spad tomorrow?

 

Mechanic: Nah, I heard it eats through rubber faster and then I have to clean your engine more often. I don't think this is going to happen. You know my back hurts and all that stuff.

 

Pilot: Yeah you are probably right. Hey do you want to have a beer with schnapps? I heard it enhances your toxication.

 

Mechanic: Sure why not!

Interesting thought experiment. Let’s add in the kommandant:

 

“Why were you engaged at such a low altitude when our engines allow dominance up high? Why should we mix a special fuel just for your dangerous low level fights that have killed many aces like Manfred?”

I also remember you once telling me that the DVIIF could outdive the XIII but that German doctrine wouldn’t allow them to chase the SPADs down. Wouldn’t that apply here also? 
 

Jon Guttman’s book SPAD XIII vs Fokker DVII has extracts from both US and German Fokker pilots, the former highlighting how to escape in a dive and the latter complaining that they couldn’t follow the Americans down when they did. Either the SPAD was a much better diver or the Germans didn’t allow pursuit. Either way, why would you need a new fuel mixture to chase at SL?

 

Sounds like your fictional pilot flies on the Flugpark in 2023 not the Western Front in 1918.

Edited February 6, 2023 by US103_Rummell

[J99_Sizzlorr]

5 minutes ago, US103_Rummell said:

Jon Guttman’s book SPAD XIII vs Fokker DVII has extracts from both US and German Fokker pilots, the former highlighting how to escape in a dive and the latter complaining that they couldn’t follow the Americans down when they did. Either the SPAD was a much better diver or the Germans didn’t allow pursuit. Either way, why would you need a new fuel mixture to chase at SL?

Aren't those anecdotes which proof nothing as we learned here...

It was just  joke to show my point.

 

5 minutes ago, US103_Rummell said:

I also remember you once telling me that the DVIIF could outdive the XIII but that German doctrine wouldn’t allow them to chase the SPADs down. Wouldn’t that apply here also? 

I never said that I said: The reason for not giving chase most of the time were their doctrines and tactics. I never said it could outdive it.

Edited February 6, 2023 by J99_Sizzlorr

[Holtzauge]

 

3 hours ago, J99_Sizzlorr said:

Just could have said this earlier that your simulation doesn't take other fuels into account.

 

As much as I hate to have to repeat myself this seems necessary since you don't seem to get it: You have insinuated (and continue to do so with this post) that me not having modeled different fuels is a shortcoming. I have told you that I assume certain powers with altitude in my simulation. This was why I asked you to specify why this was a limitation in the modeling, and what was the power that could be assumed with the different fuels. It's beginning to looks like you simply can't but still want to score some point that fuels are not modeled.

 

3 hours ago, J99_Sizzlorr said:

Then don't ask for it.

 

I never did. I asked for power levels associated with different types of fuel. You volunteered the fractions of fuel percentages and summer and winter mixtures. Maybe because it looks impressive and scientific.

 

3 hours ago, J99_Sizzlorr said:

I don't think they changed the carburetor but they set it differently. They have an H-setting and a V-setting and they can tune in between as I understand. If you look at the graph from Mercedes Werke Stuttgart you see the different settings of the carburateor they are called "Stellung des Vergasers" in German and you can see the H-Stellung and the V-Stellung. I really don't understand how these carburetors work I mean I know what they do but don't know how. Anyway I can see that they did something different with it depending on what fuel was used or what altitude it was set for.

 

Well, I think @ZachariasX pretty much explained this to you so it looks like this could be closed  then.

 

2 hours ago, ZachariasX said:

That AFAIK done with the throttle. The throttle lever could be walked forward to the "V" mark that indicated "Vollgas" (full  power) and then beyond that to the end of the travel where the "H" Mark was, "Höhengas". That is where the letters come from and reflect from when on the engine uses Höhengas. The position from when the engine reached full Höhengas is marked on the power curve.............................It's really, really hard to beat isooctane in feeding Otto engines.

 

Great info! Did not have the German side of it before but this then pretty much confirms what the British concluded: The carburetor design limits the power you can take out of the engine at lower altitudes.

 

55 minutes ago, ZachariasX said:

In principle, I do think Göring might ......................This means, I would be looking for documented change in engine setup (even somewhere in the field) if the operator is certain that his fuel is now a gamechanger and engines should adapt. But I have not seen any of that. Hence, I'd say the manual still applies. .....................At least with the BMW.

 

Agree completely. In addition, as I posted before: If the developers start to deviate from the manual limitations where does it end? They will be absolutely swamped with request based on obscure theories some of which are bound to have no anchoring in reality.....

 

 

20 minutes ago, J99_Sizzlorr said:

Mechanic: Hey how is the war going?

 

Pilot: Pretty stiff you know, I heard that we are going on the offensive again for the Kaiser as a last effort.

 

Mechanic: Uh.. sounds rough. How was flying today?

 

Pilot: Well I nearly got a Spad but he then dived to the deck and escaped me, because I couldn't follow.

 

Mechanic: Yeah that's a bummer.

 

Pilot: You know I heard there are 100 waggons of that fuel called "Fliersfuel" (Fliegerbenzin) with higher octane that would enable me to use the Höhengas even lower than advised in the manual because it has higher combustion resistance, which Austria-Hungary had to deliver to us for the sacking of Romania. It is just sitting in Ludendorffs garden and he is watering his plants with it and cleaning his windows and has no other appearant use. Do you think you could fuel up my Fokker with it so that I can get that Spad tomorrow?

 

Mechanic: Nah, I heard it eats through rubber faster and then I have to clean your engine more often. I don't think this is going to happen. You know my back hurts and all that stuff.

 

Pilot: Yeah you are probably right. Hey do you want to have a beer with schnapps? I heard it enhances your toxication.

 

Mechanic: Sure why not!

 

Good story! You should stick to fiction! You really have a knack for it!

[J99_Sizzlorr]

Quote

I am sorry you wrote earlier: What are the compositions of "Benzin" and Benzol" in Kutzbachs figures?

 

They either used the winter varaiant or the summer variant which I don't know. I just thought you asked for the composition of it. So I didn't know which one they used I listed the composition of both vriants.

 

Will some please read Bletchleys article about it I referenced in an earlier post? I never meant to say it is a shortcoming that your simulation does not regard it and I am not implying it. I was just asking for myself because I stumbled upon something I couldn't understand and tried to search for answers but couldn't find much on it that is why I wanted to know if your book is going to cover that somehow and has the answers I was looking for. But just because your simulation does not cover it you can not say it didn't happen when there is clear evidence that it did happen.

Edited February 7, 2023 by J99_Sizzlorr

[No.23_Starling]

5 minutes ago, J99_Sizzlorr said:

Aren't those anecdotes which proof nothing as we learned here...

It was just  joke to show my point.

 

I never said that I said: The reason for not giving chase most of the time were their doctrines and tactics. I never said it could outdive it.

Sooo if their tactics didn’t allow them to dive why would they need to mess about with special fuel mixes to fight at SL? What’s your source on the doctrine? Would love to read that book.

 

I can see why Sizzlor might need it to better hunt SPADs in multiplayer but not your average Jasta in 1918.

[J99_Sizzlorr]

Before telling me again how biased I am read the article, and I need to repeat myself I don't want anything changed in the game I am just curious...

 

 

Edited February 6, 2023 by J99_Sizzlorr

[Holtzauge]

15 minutes ago, J99_Sizzlorr said:

Will some please read Bleachies article about it I referenced in an earlier post? I never meant to say it is a shortcoming that your simulation does not regard it and I am not implying it. I was just asking for myself because I stumbled upon something I couldn't understand and tried to search for answers but couldn't find much on it that is why I wanted to know if your book is going to cover that somehow.

 

OK good. Then you will be happy to know that I too in the modeling (Just like Bletchley to whom you refer) assume not 160 hp but even 185 hp for the Mercedes D.IIIaü at 1400 rpm sea level so there is no conflict. This is actually even 5 hp more than the standard D.IIIa, but the thing with the D.IIIaü is that it can keep the power better with altitude which is what I posted results on here in this thread.

 

I get the impression you have a soft spot for the German planes and the Albatros in particular? If so you should be happy with the simulations!

 

Just look at how much better it performs! Climbs like a rocket and even outturns the Nieuport 28.C1 with the D.IIIaü engine!

 

What do you have to complain about? 

[J99_Sizzlorr]

I am not complaining at all but you make it look like I personally attack you or your simulations with my curiosity, which I never intended to do. I don't say something against your results either I just wanted to know what kind of variables are regarded in you simulation and then decide for myself if that is of interest to me in the case I am currently looking into. That is all.

[Holtzauge]

Just now, J99_Sizzlorr said:

I am not complaining at all but you make it look like I personally attack you or your simulations with my curiosity, which I never intended to do. I don't say something against your results either I just wanted to know what kind of variables are regarded in you simulation and then decide for myself if that is of interest to me in the case I am currently looking into. That is all.

 

You know my last post was a kind of peace offering but since you insist: The first post you did here in this thread was basically asking it to be shut down. The second was connected to an anatomical enlarger device that you and Zooropa seem to be in need of so excuse me for not being overly enthusiastic! 

[J99_Sizzlorr]

My last post was basically asking why you think we are fighting in the first place? My first post here was not asking to shut it down but acknowledging that it has not been shut down and concluding that it might be of interest for the devs. You got me wrong there as well and I am sorry if you read it the other way. But this explains your attitude towards me and my questions a little better now. I think a bit of humor fits everywhere