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

[J99_Sizzlorr]

13 hours ago, ZachariasX said:

 

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.

It had to do with the lower freezing point.

Edited February 6, 2023 by J99_Sizzlorr

[ZachariasX]

Actually, I sypathisize a lot with @J99_Sizzlorrs reasoning, because initially that was my take on the engine as well. But during my attempt to reverse engeneer the functionaltity of the BMW DIIIa carburettor arrangement here:

 

 

I made many simulations on the effect of different fuels on power output used with the engine in a state as documented. This using the sources from The Aerodrome etc. and what has been mentioned here so far. But no matter what I did, any diffrent fuel gave at best similar performance or worse. But only with a carb layout as used on the Hisso engines, I could tap the theoretical max performance at the price of letting a "185 hp engine" run at 260 hp down low while achiving acceptable power levels at "working altitude". Essentially a different engine.

 

My coclusion from that is a trivial one: BMW made a stellar job of getting the most power from the juice they just happened to have at hand. I find it remarkable that they (quiet on purpose) used the leaning of the mixture as mean to throttle the excess power down low and in consequence they made an extremely fuel efficient engine, the only real downside being its size and weight. The throttling by leaning the mixture is carefully balanced in the arrangement and works best with standard fuel blends of the time. Changing the fuel requires you to rebuild your carb. What BMW did build is a naturally aspirated 185 hp engine that gave you almost 180 hp at 3000 m! That is quiet something. The 220 hp Hisso only does some ~150 hp up there...

 

Similarly, you will not get more power by using V-Power instead of 98 octane fuel for your car, because your Otto engine is designed for 98 octane. But it is easy to tank your mileage by using esoteric blends.

 

Also, a "185 hp" engine probably has a lubrication system for a 185 hp engine. Running that at 260 hp is an accident in waiting. Marseille paid with his life for this kind of constuction flaw.

[J99_Sizzlorr]

1 hour ago, ZachariasX said:

Actually, I sypathisize a lot with @J99_Sizzlorrs reasoning, because initially that was my take on the engine as well. But during my attempt to reverse engeneer the functionaltity of the BMW DIIIa carburettor arrangement here:

 

I made many simulations on the effect of different fuels on power output used with the engine in a state as documented. This using the sources from The Aerodrome etc. and what has been mentioned here so far. But no matter what I did, any diffrent fuel gave at best similar performance or worse. But only with a carb layout as used on the Hisso engines, I could tap the theoretical max performance at the price of letting a "185 hp engine" run at 260 hp down low while achiving acceptable power levels at "working altitude". Essentially a different engine.

 

My coclusion from that is a trivial one: BMW made a stellar job of getting the most power from the juice they just happened to have at hand. I find it remarkable that they (quiet on purpose) used the leaning of the mixture as mean to throttle the excess power down low and in consequence they made an extremely fuel efficient engine, the only real downside being its size and weight. The throttling by leaning the mixture is carefully balanced in the arrangement and works best with standard fuel blends of the time. Changing the fuel requires you to rebuild your carb. What BMW did build is a naturally aspirated 185 hp engine that gave you almost 180 hp at 3000 m! That is quiet something. The 220 hp Hisso only does some ~150 hp up there...

 

Similarly, you will not get more power by using V-Power instead of 98 octane fuel for your car, because your Otto engine is designed for 98 octane. But it is easy to tank your mileage by using esoteric blends.

 

Also, a "185 hp" engine probably has a lubrication system for a 185 hp engine. Running that at 260 hp is an accident in waiting. Marseille paid with his life for this kind of constuction flaw.

BMW has still some of the most reliable and forgiving engines in the world. The thing is for the BMW engine they needed the benzol streched fuel to get into the higher compression range according to the article I shared it probably ran on nothing else. This is where the assumption the F designation stands for Fliegerbenzin comes in, but when thinking about it it doesn't make any sense that the F stands for Fliegerbenzin when the other fuel available was called Flugbenzin. While the Merceds D.IIIaü could run on both the higher octane Fliegerbenzin and the normal Flugbenzin. So they had both in various quanteties and could choose which one to use on Jasta level. The British tests done with the Mercedes D.IIIaü and the Maybach engine showed that they 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 Höhenmotoren 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. So it seems they got around the carburator somehow. This is all according to the article I shared, sources can be found there.

Also things like degrading engine and eating through rubber weren't of any concern to the Germans, because they ran all their ground engines like cars and lorries on benzol streched fuel since 1916 with no apparent issues according to the article.

Edited February 7, 2023 by J99_Sizzlorr

[J5_Adam]

Ethanol is horrible for older engines that use rubber products. I have a few 1950's and 1960's Mercury outboards. If you run ethanol gas with them it destroys anything rubber in the engine. The original old fuel lines break down and clog up your carbs. You stand a chance of ruining your engine. Vintage motors with rubber parts etc need ethanol free gas. Luckily Chevron 94 and Shell  91 in Canada both are ethanol free. 

 

My 2 cents.

Edited February 7, 2023 by J5_Adam

[J99_Sizzlorr]

12 minutes ago, J5_Adam said:

Ethanol is horrible for older engines that use rubber products. I have a few 1950's and 1960's Mercury outboards. If you run ethanol gas with them it destroys anything rubber in the engine. The original old fuel lines break down and clog up your carbs. You stand a chance of ruining your engine. Vintage motors with rubber parts etc need ethanol free gas. Luckily Chevron 94 and Shell  91 in Canada both are ethanol free. 

 

My 2 cents.

They used benzol-alcohol-gasoline mixture or sometimes only benzol-alcohol. Ethanol was me mixing things up I guess. I am no chemist.

Edited February 7, 2023 by J99_Sizzlorr

[Holtzauge]

Since this thread is about The Nieuport N28.C1 and Albatros D.Va, the Mercedes D.IIIaü is certainly on topic and from what I saw yesterday, there is still no evidence that they fitted other carburetors that those that made the engine choke if you opened them up to early, i.e. the Höhengas variant. So from this perspective I think the simulation figures posted here are still valid.

 

When it comes to the BMW DIIIa this is different since I believe the Höhengas could be engaged just as it has been implemented in-game. However, if you open it up to full throttle at lower altitudes the engine will detonate due to the octane level of the fuel being too low.

 

But we do of course know that the British in tests after the war ran the engine flat out at SL and extracted 234 hp at 1400 rpm. They did this by adding Benzol. And sure, we also know that Benzol was available to the Germans.

 

So the questions here is to what extent was it done? As I said earlier on, I may (and I guess the developers may consider it too) change the modeling to allow full throttle at low level as well if compelling evidence that this was being done is presented.

 

Until then, my assumption is that the engine will be able to deliver 209 hp up to a FTH of 2.1 Km which is in essence based on the power chart from the NACA test @ZachariasXposted above.

 

Page 106 from my book WW1 Aircraft Performance:

 

 

In addition: Here are a few previous posts I did on the subject of spiked fuel for the BMW engine:

 

https://forum.il2sturmovik.com/topic/75570-analysis-of-the-bmw-iiia-and-the-function-of-höhengas/?do=findComment&comment=1145132

 

https://forum.il2sturmovik.com/topic/75570-analysis-of-the-bmw-iiia-and-the-function-of-höhengas/?do=findComment&comment=1145143

 

https://forum.il2sturmovik.com/topic/75570-analysis-of-the-bmw-iiia-and-the-function-of-höhengas/?do=findComment&comment=1145156

 

 

So I am certainly not against it. OTOH I can think of better things to implement in game.

 

I mean, it's not like the in-game Fokker D.VIIF is lacking in performance is it? 

 

 

 

 

Edited February 7, 2023 by Holtzauge

[J99_Sizzlorr]

1 hour ago, Holtzauge said:

So I am certainly not against it. OTOH I can think of better things to implement in game.

 

I mean, it's not like the in-game Fokker D.VIIF is lacking in performance is it? 

I don't know are we trying to be accordig to history or are we trying to balance a game? 

1 hour ago, Holtzauge said:

So the questions here is to what extent was it done? As I said earlier on, I may (and I guess the developers may consider it too) change the modeling to allow full throttle at low level as well if compelling evidence that this was being done is presented.

It was done on a big scale not only in the automobile sector since 1916* but also in aviation since spring 1918.

 

*

'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.

Edited February 7, 2023 by J99_Sizzlorr

[Holtzauge]

1 minute ago, J99_Sizzlorr said:

I don't know are we trying to be accordig to history or are we trying to balance a game? 

 

You know : Just keep going: I don't have many people on my ignore list but you are looking like a better candidate every day.

 

Why don't you instead of working towards that goal, do something constructive and find that evidence for special carburetors on D.IIIaü engines and that high octane fuel instead?

[J99_Sizzlorr]

What is it I have done wrong again this time? Why are you always trying to provoke me? And personally attack me?

 

I'm just asking questions. Is your goal to work towards historical accurracy and take into account that Fliegerbenzin with higher octane and therefore better knocking resistance existed in vast quantities in Germany and was used at the front when everything I brought up points to that or are you trying to balance a game?

 

I think this is a totally valid question after you said that it is possible for the BMW engine to run the Fliegerbenzin through the carburator but this is not on your priority list because you personally don't think the Fokker D.VIIF needs it. Totally understand that Mercedes D.IIIaü thing and that more information about the carburator settings are needed.

[Holtzauge]

 

OK @J99_Sizzlorr: That's it. I'm placing you on ignore. I have no use for interacting with people who do not shoot straight:

 

You have now gone back and edited and added content in a post I had already responded to.

 

When I quoted you, you had only posted this:

 

2 hours ago, J99_Sizzlorr said:

I don't know are we trying to be accordig to history or are we trying to balance a game? 

 

You even added a new quote from me that was not there when I responded. And also took the opportunity to add "evidence" making it look like I was ignoring this in my response. This makes it look like I just selectively responded to something you posted and asked for something that was already there which is nothing short of being deceitful.

 

And by way of a Parthian arrow: If you think what you redacted into that post constitutes evidence then I predict you will have quite an uphill struggle to convince the developers.

 

[J99_Sizzlorr]

I am sorry I always re read my posts and have to edit them sometimes after I send them to make sure I get understood. English is not my native language. Didn't know it was deceitful to edit posts. I am sure you did it as well at some point.

[J99_Sizzlorr]

For anyone interested here is more on the carburator use with benzol mixed fuel on the Mercedes D.IIIaü: 

 

Edit: http://www.theaerodrome.com/forum/showpost.php?p=451600&postcount=4

 

http://www.theaerodrome.com/forum/showpost.php?p=521822&postcount=1

Edited February 11, 2023 by J99_Sizzlorr

[No.23_Starling]

12 hours ago, J99_Sizzlorr said:

For anyone interested here is more on the carburator use with benzol mixed fuel on the Mercedes D.IIIaü: 

 

Edit: http://www.theaerodrome.com/forum/showpost.php?p=451600&postcount=4

 

http://www.theaerodrome.com/forum/showpost.php?p=521822&postcount=1

Thanks for sharing - an interesting read. The first thread mentions Duchamps which I think is this book: https://www.abebooks.co.uk/Prüfung-Wertung-Weiterentwicklung-Flugmotoren-Dechamps-Kutzbach/15780587279/bd which I dont own so cant confirm, but at no point quotes any additional source or passage alluding to the breaking of the 'suggested' altitude power setting and moving the throttle forward partially - the post doesnt say fully - to achieve 175-180 PS. The fact that Mercedes / Fokker / Albatros Flugzeugwerke put the setting on the throttle begs the question why if the benzol mix prevented detonation? The post doesn't tell us:

 

1. Who these people posting are, their academic/engineering credentials

2. Any evidence of widespread use of benzol for all types and engines in 1918 - I've not seen a single book quoted or primary evidence referenced, just people like us posting without book page references or quotes from sources

3. Any evidence, either primary source or secondary, that Jasta pilots routinely pushed their Mercedes Diiiau throttles beyond the factory recommended setting to give them a boost at low alt

4. Why Mercedes / the Flugzeugwerke didnt just adjust the throttle to reflect the possible lower alt power output based on pilot feedback. WW1 planes were constantly tweaked following feedback from pilots - think Richthofen with the DVII and Ball with the SE5

5. Tactical reasoning for why they needed low-alt boost when most combat by 1918 was taking place high up - exactly why the AU and BMW was loved/hated, and why the French ordered Dolphins in late 1918 and were experimenting with the Rateau supercharger in the SPAD (see JM Bruce, Air International 10)

 

I see some scant evidence of this practice and why gamers (like you) would want to be able to do this, but nothing more. Do post some non-forum links like book quotes or primary sources if you have them.

 

Salute.

 

[Holtzauge]

All very good points @US103_Rummell: Basing judgements on singular quotes can sometimes be misleading. I too, have scourged The Aerodrome forum for information and I have in addition gotten some very good information directly from Bletchley personally, and in addition, I also read some very good points from Dan San Abbot, both very knowledgeable people (although info from Dan San Abbot of course now days is posthumous).

 

As an example, here is another quote from Bletchley:

 

"I think the BMW could have developed more than 185 PS, for a short period in an emergency, at altitudes below 3200 m, but I am not sure how much - I very much doubt it could achieve anything like the theoretical 260 PS at sea level. Udet records that he could get a slightly higher rpm at lower altitudes with the use of the secondary throttle (the 'overgas'), but at very low level (below 1000 m) the BMW IIIa was already running very close to the limits of combustion (AFR of 20:1). In a text fom the period Marks comments that:

 

'this mixture is so close to the limit of explosibility that slight changes in condition might result in exceeding that limit... a value of 20 at ground level is seldom exceeded' although he does add that an AFR of up to 23:1 might be possible under some conditions, but that there would be significant risk (an increasing risk) of an engine cut-out as the mixture was leaned between 20:1 and 23:1 - not something you would want to risk at very low altitude.

 

Normal low-octane petroleum would cause detonation long before that point was reached, but the benzol additive in the fuel reduced this threshold and allowed the engine to run smoothly at very lean mixtures - the problem is, we just don't know how much benzol they used, or what effect this had. I suspect that at low altitude (at around 1000 m) the 'over gas' secondary throttle could be engaged to get a marginal boost, as Udet describes. Lothar von R. describes the low altitude (to 2000 m) performance of the BMW as insignificantly better than that of the D.III, and I think Goering exagerates this performance to be first for a priority supply of the new engine. As I see it, the engine gave a constant 185 PS to 3200 m, the full throttle height, and then power fell off at the normal rate."

 

 

PS: The book about WW1 Aircraft Performance is now out: https://forum.il2sturmovik.com/topic/82895-new-book-on-ww1-aircraft-design-and-performance/

 

 

Edited February 11, 2023 by Holtzauge

[ZachariasX]

26 minutes ago, US103_Rummell said:

The first thread mentions Duchamps which I think is this book: https://www.abebooks.co.uk/Prüfung-Wertung-Weiterentwicklung-Flugmotoren-Dechamps-Kutzbach/15780587279/bd which I dont own so cant confirm, but at no point quotes any additional source or passage alluding to the breaking of the 'suggested' altitude power setting and moving the throttle forward partially - the post doesnt say fully - to achieve 175-180 PS.

I just bought that very book...

[Holtzauge]

3 minutes ago, ZachariasX said:

I just bought that very book...

 

Will be very interested in what it says!

[J99_Sizzlorr]

7 minutes ago, Holtzauge said:

Normal low-octane petroleum would cause detonation long before that point was reached, but the benzol additive in the fuel reduced this threshold and allowed the engine to run smoothly at very lean mixtures - the problem is, we just don't know how much benzol they used, or what effect this had.

We know they used 50%-60% benzol in their fuels based on the seasons. There are also engine test done with benzol to look for the effects.

4 minutes ago, ZachariasX said:

I just bought that very book...

Hope the condition is good. Is it a rebind?

[No.23_Starling]

16 minutes ago, Holtzauge said:

 

Will be very interested in what it says!

Could you share with us what you find? 

20 minutes ago, J99_Sizzlorr said:

We know they used 50%-60% benzol in their fuels based on the seasons. There are also engine test done with benzol to look for the effects.

Hope the condition is good. Is it a rebind?

What’s your source on the 50-60% for all Jastas and all types in 1918? Engine tests don’t equal deployment.

 

Who is ‘we’ that know this? If ‘we’ did there wouldn’t be a discussion.

[Holtzauge]

10 minutes ago, US103_Rummell said:

Could you share with us what you find? 

 

Absolutely. And I guess the first step is to see what @ZachariasX makes of the Dechamps/Kutzbach book when he gets it. But of course I will share whatever updates I do in the simulation model going forward based on any new data that comes in.

 

[ZachariasX]

29 minutes ago, J99_Sizzlorr said:

Hope the condition is good. Is it a rebind?

The are not sure. Miight be, might be that the print on the cover faded. The descripiion was ambiguous, whether the "defects" mainly adress the cover or also some of the containing articles. We'll see. But at that price point I figured i take the chances.

 

15 minutes ago, US103_Rummell said:

Could you share with us what you find? 

As i understand it, these are a collection of articles. I intend to scan and share relevant passages if they are sufficient quality.

[J99_Sizzlorr]

25 minutes ago, US103_Rummell said:

Could you share with us what you find? 

What’s your source on the 50-60% for all Jastas and all types in 1918? Engine tests don’t equal deployment.

 

Who is ‘we’ that know this? If ‘we’ did there wouldn’t be a discussion.

Quote

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 'Schwerbenzin', with a reduced aromatic content (to around 35%) that reduced the freezing point and allowed for high-altitude winter flying (Reinhardt; also Dechamps & Kutzbach). Edit: Quote from Betchley article: Central Powers making a little go a long way.

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

Dechamps H. / Kutzbach K.: Prüfung, Wartung und Weiterentwicklung von Flugmotoren, Richard Carl Schmidt, 1921

Edited February 11, 2023 by J99_Sizzlorr

[No.23_Starling]

33 minutes ago, J99_Sizzlorr said:

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

Dechamps H. / Kutzbach K.: Prüfung, Wartung und Weiterentwicklung von Flugmotoren, Richard Carl Schmidt, 1921

Can you post a screenshot of the pages and quotes from the sources?

[J99_Sizzlorr]

2 minutes ago, US103_Rummell said:

Can you post a screenshot of the pages and quotes from the sources?

No, I don't have them, they are too heavily priced for me and probably in a bad condition but Zach has at least ordered one of those two books and he is going to do it, when the articles are in good enough quality.

 

Edit: But I trust Bletchley did his homework. 

Edited February 11, 2023 by J99_Sizzlorr

[No.23_Starling]

18 minutes ago, J99_Sizzlorr said:

No, I don't have them, they are too heavily priced for me and probably in a bad condition but Zach has at least ordered one of those two books and he is going to do it, when the articles are in good enough quality.

 

Edit: But I trust Bletchley did his homework. 

Ok, let’s see what Zatch can get from that book. I’d love to have a read (with my crap German). 
 

NB Bletchley in that old post - I still don’t know what his qualifications are including if he’s a respected historian with multiple publications like Guttman - doesn’t say anything like “all Jastas recommended that the engine of all Merc Diiiau and BMW types be pushed above the recommended limit below 1800m”. He says that some pilots seem to have done it and that was because of the benzol mixture. You’re putting a lot of trust in one person who posts on an enthusiast forum.

 

We might end up in the same realm of the CL2 cannon discussion - it did happen, but was it common or even needed when combat took place up high?

[J99_Sizzlorr]

51 minutes ago, US103_Rummell said:

Ok, let’s see what Zatch can get from that book. I’d love to have a read (with my crap German). 
 

NB Bletchley in that old post - I still don’t know what his qualifications are including if he’s a respected historian with multiple publications like Guttman - doesn’t say anything like “all Jastas recommended that the engine of all Merc Diiiau and BMW types be pushed above the recommended limit below 1800m”. He says that some pilots seem to have done it and that was because of the benzol mixture. You’re putting a lot of trust in one person who posts on an enthusiast forum.

 

We might end up in the same realm of the CL2 cannon discussion - it did happen, but was it common or even needed when combat took place up high?

From what I have read from him I can tell that he probably knows a lot more about Mercedes engines then us two combined.

 

Edit: It is also up there for many years on the Aerodrome forum and no one has proven him otherwise.

 

Edit2: It is also kind of a low stake situation for me as I only try to learn more about the German engines here.

Edited February 11, 2023 by J99_Sizzlorr

[No.23_Starling]

2 hours ago, J99_Sizzlorr said:

From what I have read from him I can tell that he probably knows a lot more about Mercedes engines then us two combined.

 

Edit: It is also up there for many years on the Aerodrome forum and no one has proven him otherwise.

 

Edit2: It is also kind of a low stake situation for me as I only try to learn more about the German engines here.

Yeah he seems well-read but I don’t know anything else about him. That’s why I want to get my hands on his books ?

 

I also want to understand better the engineering and military practices (mostly so we can have good data should anyone ever want to add in Merc Diiiau engine - *hint hint 1C*!!). S!

[Holtzauge]

I already posted this above but it looks like it was not read (or simple ignored as inconvenient) so here goes again. This time with salient points highlighted in red since this seems necessary:

 

Also a Bletchley quote from The Aerodome forum:

 

"Normal low-octane petroleum would cause detonation long before that point was reached, but the benzol additive in the fuel reduced this threshold and allowed the engine to run smoothly at very lean mixtures - the problem is, we just don't know how much benzol they used, or what effect this had. I suspect that at low altitude (at around 1000 m) the 'over gas' secondary throttle could be engaged to get a marginal boost, as Udet describes. Lothar von R. describes the low altitude (to 2000 m) performance of the BMW as insignificantly better than that of the D.III, and I think Goering exagerates this performance to be first for a priority supply of the new engine. As I see it, the engine gave a constant 185 PS to 3200 m, the full throttle height, and then power fell off at the normal rate."

 

So here we have Bletchley saying the BMW DIIIa delivered no more than 185 hp up to a FTH of 3200 m.

 

So is this how we should model the power now? Bletchley has so far been quoted as the gospel so I guess we should?

 

So it's 185 hp up to 3200 m then is it? Looks like I have been far to optimistic assuming 209 hp up to 2100 m in my book then......

 

Or maybe a good start here would be to not only pick the raisins from the pudding, but to acknowledge that this is not a slam dunk case. Pulling a few quotes out of a hat to support an agenda is not very helpful at all.

 

Which bring us full circle: The onus is on those who claim that the BMW DIIIa was run at full blast pedal to the metal from SL up to provide the evidence that this was the case.

 

Not the other way around....... 

 

 

[J99_Sizzlorr]

20 hours ago, Holtzauge said:

"Normal low-octane petroleum would cause detonation long before that point was reached, but the benzol additive in the fuel reduced this threshold and allowed the engine to run smoothly at very lean mixtures - the problem is, we just don't know how much benzol they used, or what effect this had. I suspect that at low altitude (at around 1000 m) the 'over gas' secondary throttle could be engaged to get a marginal boost, as Udet describes. Lothar von R. describes the low altitude (to 2000 m) performance of the BMW as insignificantly better than that of the D.III, and I think Goering exagerates this performance to be first for a priority supply of the new engine. As I see it, the engine gave a constant 185 PS to 3200 m, the full throttle height, and then power fell off at the normal rate."

A little bit off topic but if you fly the engine as it was intended to it probably did excactly 185 PS up tp 3200m. There is nothing wrong with that statement. The question is what happens if you fly it otherwise and I think the Spitzenleistung for the BMW IIIa was around 220-240 PS because BMW advertised the engine to do that. A benzol mixed fuel might be responsible for that.

 

Edit: When Lothar von Richthofen describes the BMW as insignificantly better than the Mercedes at altitudes below 2000m and the BMW delivered  constant 185 PS up to that altitude how much would the Mercedes engine do to be insignificantly worse than the BMW? Probably 180PS right?

 

Nevertheless even pure benzol could be used with the BMW IIIa they (BMW) even state it in their manual that no changes to the carburator has to be made even though the engine performs slightly better with Benzin.

(Beschreibung und Bertriebsanleitung für den 185 PS Bayern-Flugmotor Type BMW IIIa page 32). Why would they add that if no one ever did that besides for tests?

They also state that it is possible to get all the power available at the given altitude out of the engine by advancing the Höhengashebel fully and then just regulate the engine with the Normalgashebel during a dogfight. They add that the engine should not operate without urgency above the regular rpms (Beschreibung und Bertriebsanleitung für den 185 PS Bayern-Flugmotor Type BMW IIIa page 39ff.).

Edited February 12, 2023 by J99_Sizzlorr

[J99_Sizzlorr]

On 2/11/2023 at 3:12 PM, US103_Rummell said:

1. Who these people posting are, their academic/engineering credentials

2. Any evidence of widespread use of benzol for all types and engines in 1918 - I've not seen a single book quoted or primary evidence referenced, just people like us posting without book page references or quotes from sources

3. Any evidence, either primary source or secondary, that Jasta pilots routinely pushed their Mercedes Diiiau throttles beyond the factory recommended setting to give them a boost at low alt

4. Why Mercedes / the Flugzeugwerke didnt just adjust the throttle to reflect the possible lower alt power output based on pilot feedback. WW1 planes were constantly tweaked following feedback from pilots - think Richthofen with the DVII and Ball with the SE5

5. Tactical reasoning for why they needed low-alt boost when most combat by 1918 was taking place high up - exactly why the AU and BMW was loved/hated, and why the French ordered Dolphins in late 1918 and were experimenting with the Rateau supercharger in the SPAD (see JM Bruce, Air International 10)

 

I see some scant evidence of this practice and why gamers (like you) would want to be able to do this, but nothing more. Do post some non-forum links like book quotes or primary sources if you have them.

 

Salute.

 

1. One of the persons discussing in the Aerodrome thread was Dan San Abbot, he wrote books like the one you have on your desk called: "Schlachtflieger"

2. I have found this quote: 

Quote

Die Brennstoffe.

 

Als Brennstoffe kommen zurzeit bei Flugmotoren nur

Benzin und Benzol in Frage. Während man zu Anfang aus-

schlieBlich das teure, ganz leichte Benzin benutzte, wodurch

sich der Flugbetrieb bei den starken Motoren recht teuer

stellte, geht man jetzt mehr und mehr zu dem billigeren,

einheimischen Erzeugnis, dem Benzol, über. Haufig benutzt

man auch Mischungen von Benzin und Benzol.

 

Unter Benzin versteht man bekanntlich leichtflüchige

Bestandteile des Erdöls, von denen es befreit werden muB,

um ihm in den Lampen seine Explosionsfähigkeit zu nehmen.

Es hat ein spezifisches Gewicht von 0,67 — 0,72 (Schwer-

benzin bis 0,77). Sein Heizwert betragt etwa 10000 Wärme-

einheiten.

Huth, Fritz (1920) : Motoren für Flugzeuge und Luftschiffe; Luftfahrttechnik 1920;  S.17

3. Not for the Mercedes D.IIIaü but if you count Görings letter as primary source then there are accounts of it that it was done with the BMW IIIa engine, which also could be run with pure benzol accoridng to the Betriebsanleitung of the engine (Beschreibung und Bertriebsanleitung für den 185 PS Bayern-Flugmotor Type BMW IIIa page 32).

4.I can not tell you that old friend. I don't know what pilots or groundcrews did to the throttle.

5. Tactical operations probably started higher up but we all know that dogfights tend to end lower than they started. And when the pilot wants to get back to base safely he probably could make a good use of that boost. Other tactical opertions woudn't require high altitudes like protecting or attacking balloons for example  which is the talk of in Görings letter. 

Edited February 12, 2023 by J99_Sizzlorr

[Holtzauge]

The picture below is from BMW’s own user manual for the “185 PS” BMW IIIa. (BTW: I wonder why they call it the 185 hp engine? )

 

Note that it says that preferred fuel is “Normalbenzin” with a specific weight of at least 0,72.

 

But that higher specific weight fuel CAN be used OR Benzol without mucking about with the carburetor.

 

However, it also specifically says that performance is LESSENED and that the engine runs more ROUGH when run on these substitutes and that the engine does not run AS WELL as when run on “Normalbenzin”, i.e. ordinary fuel.

 

So here we see that the used of Benzol is as a SUBSTITUTE for the good stuff BMW wants you to run the engine on which is Normalbenzin.

 

So nowhere in this manual is there any word of spicing up your Normalbenzin with Benzol to raise the octane level.

 

In fact, what this tells us is that in the opinion of the manufacturers of the BMW DIIIa engine, Benzol MAY be used as a SUBSTITUTE for the good stuff nothing else.

 

 

 

 

Edited February 12, 2023 by Holtzauge

[J99_Sizzlorr]

On 2/12/2023 at 5:55 PM, Holtzauge said:

The picture below is from BMW’s own user manual for the “185 PS” BMW IIIa. (BTW: I wonder why they call it the 185 hp engine? )

 

Note that it says that preferred fuel is “Normalbenzin” with a specific weight of at least 0,72.

 

But that higher specific weight fuel CAN be used OR Benzol without mucking about with the carburetor.

 

However, it also specifically says that performance is LESSENED and that the engine runs more ROUGH when run on these substitutes and that the engine does not run AS WELL as when run on “Normalbenzin”, i.e. ordinary fuel.

 

So here we see that the used of Benzol is as a SUBSTITUTE for the good stuff BMW wants you to run the engine on which is Normalbenzin.

 

So nowhere in this manual is there any word of spicing up your Normalbenzin with Benzol to raise the octane level.

 

In fact, what this tells us is that in the opinion of the manufacturers of the BMW DIIIa engine, Benzol MAY be used as a SUBSTITUTE for the good stuff nothing else.

 

 

 

 

They call it the 185 PS engine because this is what they promise it will deliver up to  certain altitude if it is flown with the Höhengas as described in the manual.

 

They however advertised their engine with a Spitzenleistung of 240 PS as can be seen on old advertising posters from BMW.

 

Exacty it tells us hey you should run it if possible with Benzin with a weight of 0,72. They probably had engine longletivity and fuel consumption in mind. But you can also run it on a pure substitute, called Benzol albeit with a little power loss as I stated in my earlier post. But it also says that you can run it on Benzin with higher weight without any concerns (ohne weiteres).

 

Let's get back to Fliegerbenzin the fuel which was a mix of benzol and benzin, which had a weight of 0,79 for the summer variant and 0,78 for the winter variant. So nowhere it says that it was not possible to do that. Or that they had any concerns if it would be done (ohne weiteres). And if the fuel BMW wants you to run your engine with to keep it in good shape in the long term is in short supply but there is a war going on and your side wants to go on the offensive you might have the idea of mixing it with the substitute of which you have plenty. Also if your concern is your longletivity and not that of your engine you might think differently on which Benzin to use.

Edited February 14, 2023 by J99_Sizzlorr

[Holtzauge]

Given how much there is to cover on the subject of fuels and how different engines were operated, I suggest that we keep this thread to what the title implies: The relative performance of the Nieuport 28.C1 and Albatros D.Va.

 

However, discussing different fuels and especially the BMW DIIIa is (while certainly interesting) a bit off topic and would be better to cover in a dedicated thread of its own. So why not open one up and continue the discussion about this there?

 

I do not know to what level the developers want to see evidence, but there was a very long and sometimes quite infected discussion about the use of 150 octane fuel during WW2 a while back in the forum.

 

Mike Williams and Neil Stirling did a tremendous job putting solid evidence together that in the end got this option implemented in-game.

 

I'm not saying as much evidence as was posted by them here is necessarily needed:

 

http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html

 

But at least some of the elements in the linked material needs to be there: E.g. showing actual use on Squadron level, detailing problem/advantages when the fuel was used, shipments and such would be good. Testimonies similar to explicitly saying engaging +25 boost etc.

 

Of course, we have to acknowledge that we can't set the bar quite so high in the case of WW1 fuel, but to be honest, I think there is a world of a difference in evidence between what has been put forward in this thread and the evidence that Mike and Neil put together for 150 octane fuel.

 

So again, those who are convinced that high octane fuel allowed the BMW DIIIa to be run at 240-260 hp from sea level up, and that the Mercedes D.IIIaü was equipped with some special high octane carburetor other than the standard one which did not allow full throttle operation until at FTH.

 

Collect the data and please start a dedicated thread about it.

 

 

Edited February 12, 2023 by Holtzauge

[J99_Sizzlorr]

Let's just assume for a moment it was the way I tried to describe it, could that explain Görings letter? I mean could a Fokker D.VIIF outfly a Spad 13 assuming it was one at an altitude of 100m? Or asking differently how much PS would the Fokker D.VIIF engine need to do that? Isn't that something you could simulate? This was my initial question I had on that subject before diving down the rabbit hole. As I have no agenda and no goal besides finding an answer to that question I will not continue the debate, even if it is very interesting one, any further here if that is inconvinient for you. I just continued with the BMW because you brought it up. I found it off topic as well and I think a seperate thread would do just fine.

Edited February 12, 2023 by J99_Sizzlorr

[No.23_Starling]

2 hours ago, Holtzauge said:

So again, those who are convinced that high octane fuel allowed the BMW DIIIa to be run at 240-260 hp from sea level up, and that the Mercedes D.IIIaü was equipped with some special high octane carburetor other than the standard one which did not allow full throttle operation until at FTH.

This is the crunch. There’s some pretty big unanswered questions:

 

1. Where is evidence of a Merc Diiiau special high octane carburettor being fitted to most/all types in 1918? Where do pilots or mechanics talk about the modification? Where are the records (a lot burned in ww2, sadly)? Why weren’t captured examples already fitted with these as they should have been late-war standard?

 

2. Why have the alt throttle with a stop point in a 1918 upgrade if pilots knew they could punch through it safely using a different fuel mix? Wouldn’t pilots have fed back to the factory this wasn’t needed? Pilots made upgrades all the time and fed that back till it was factory standard (think Ball and the SE5 alterations).

 

3. Why would you need to ever chase a SPAD to the deck in 1918 when most combat was at high alt? The BMW and AU are designed specifically for that purpose, and most pilots knew that flying low was very risky - look what happened to Mannock and Richthofen. A DVIIF who dives low loses its main advantage vs the Camels and Hispano planes.

 

4. Just the fact that Goering’s remark exists - doesn’t that tell us that is wasn’t normal practice? Anyone else not picked that up?? When was that remark made too? Late war?

 

Right now I see evidence the BMW might have been using a special fuel and pilots might have pushed it on the deck - it’s also possible that all Merc Diiiaus had special carburettas fitted for a higher octane fuel, but where is the evidence?

 

All I’m seeing here is circumstantial - if interesting - evidence. I’d welcome a separate thread with more evidence. Sizz - thanks for sharing the BMW manual; that’s very cool!

 

Edited February 12, 2023 by US103_Rummell

[J99_Sizzlorr]

Maybe@ZachariasXcan enlighten us and post more about the Betriebsstoffe from the Mercedes 200PS IIIaü Betriebsanleitung and how the throttle should be operated according to Mercedes?

 

Edit: Right now there is no evidence that Mercedes changed back to their old carburators to make use of the Fliegerbenzin. But the beatuy of never having developed a different engine block was that they could make use of their old parts in their upgraded engines and it would fit.

I think in Görings remark it is vice versa, his pilot is successfully trying to get away from Spads that are chasing him after he attacked a balloon. As you can see there are scenarios where you want that extra power near ground level.

His remark seems to come from a time where the BMW engine was relatively new and he was in command, so maybe around late spring early summer 1918.

Edited February 13, 2023 by J99_Sizzlorr

[ZachariasX]

8 hours ago, J99_Sizzlorr said:

Maybe@ZachariasXcan enlighten us and post more about the Betriebsstoffe from the Mercedes 200PS IIIaü Betriebsanleitung and how the throttle should be operated according to Mercedes?

I have currently no more info than you guys. I just happen to be weary of abusing old engines due to some personal experience.

 

If all goes well, in about three weeks time I have the book (hopefully what we are interested in is readable) and I can post some the relevant content here in a new thread for that.

[No.23_Starling]

Does anyone know this guy?

 

I’ve commented on the video to see if he could answer some questions on his engine and the throttle operation / fuel he uses. Can get much better than the actual engine.

 

 

[Holtzauge]

10 hours ago, US103_Rummell said:

Sizz - thanks for sharing the BMW manual; that’s very cool!

 

Here is the complete part of that section without the top part section 1 left out.

 

What this says is that the “Höhengas” throttle should be closed at take-off and that the ordinary throttle should be fully open. It goes on to say that when flying the following sections about engine operation should be followed closely.

 

Now why would anyone posting info about the BMW engine operation want to leave such a vital part out……..

 

 

10 hours ago, US103_Rummell said:

 I’d welcome a separate thread with more evidence. 

 

Me too!

 

20 minutes ago, US103_Rummell said:

Does anyone know this guy?

 

I’ve commented on the video to see if he could answer some questions on his engine and the throttle operation / fuel he uses. Can get much better than the actual engine.

 

 

 

Yeah, does anyone know him? Seems like an interesting guy! 

[J99_Sizzlorr]

6 hours ago, Holtzauge said:

 

Here is the complete part of that section without the top part section 1 left out.

 

What this says is that the “Höhengas” throttle should be closed at take-off and that the ordinary throttle should be fully open. It goes on to say that when flying the following sections about engine operation should be followed closely.

 

Now why would anyone posting info about the BMW engine operation want to leave such a vital part out……..

 

 

 

Me too!

 

 

Yeah, does anyone know him? Seems like an interesting guy! 

Are you done discrediting me whereever you can? You can find the whole Bertiebsanleitung of the BMW on their website. It is publicly available. I was just focusing on No2 because it showed how the Höhengasthrottle should be operated to get the 185 PS the engine promises to deliver up to a certain height. I didn't see the need to tell everybody what I assumed they already know, and no one has ever questioned besides you probably. Why did you leave out the part where it is explained how the throttles should be operated in case of a dogfight? As you can see I can play that game as well...

 

Edit: Anyway the I linked the BMW Betriebsanleitung so the readers can make up their own minds.

 

Edited February 13, 2023 by J99_Sizzlorr

[Holtzauge]

13 minutes ago, J99_Sizzlorr said:

Are you done discrediting me whereever you can? You can find the whole Bertiebsanleitung of the BMW on their website. It is publicly available. I was just focusing on No2 because it showed how the Höhengasthrottle should be operated to get the 185 PS the engine promises to deliver up to a certain height. Why did you leave out the part where it is explained how the throttles should be operated in case of a dogdight? As you can see I can play that game as well...

 

About the discrediting part I think you are doing an admirable job on your own without help from me: Accusing me of wanting to balance the game, cherry picking in Bletchley’s posts to fit your agenda, going back and editing a  post that I replied to close too two hours ago, and then like you did just now, redacting out a vital part of a section in an operating manual.

 

I have asked you a hundred times to stop posting your theories, and gather some real evidence similar to what Mike Williams and Neil Stirling has done for the 150 octane case, and to stop spamming this thread!