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

[J99_Sizzlorr]

Sorry you don't like my theories. Anyway I am done here. I don't need to post evidence because I don't have an agenda. Good luck with your book. You certanly lost a potential customer.

[J99_Sizzlorr]

When it gets from a discussion to personal insults and incorrect assumptions about me I am out. At least I was polite while discussing the topic and didn't bite at the countless accusiations I am facing here. I will continue my research regardless of course because my drive is personal interest and no agenda as people here might think but I will not share anything here anymore.

 

Edit: Just one more thing I like to share as I got told to stick with my fiction and people think I have a knack for it I will leave this here to whom ever it may humor ? :

 

March 1918: Somewhere at the western front

 

KoGenLuft: OHL can I have a word with you?

 

OHL: Ja bitte?

 

KoGenLuft: We need more fuel for the aircrafts for your “All or nothing spring offensive”!

 

OHL: Why? What’s wrong? We recaptured Romanian oilfields you get more than you did last year.

 

KoGenLuft: Yes true, but we also have to fuel a lot more aircrafts thanks to the “Amerika Programm” now and flying hours are going to increase with the better weather in spring anyway.

 

OHL: Hm, that is a bummer we can’t get any more fuel, you know the Brits are naval blocking us.

 

German Coke Industry: Sorry to interrupt but we produce this stuff called benzol you could add that to your fuel to stretch it. We produce more of that than the USA and more of that than the rest of the Entente together. We also use this for our cars and lorries on the frontline since 1916 without any issues.

 

Chemists: We experimented with benzol in fuels for airplanes at Adlershof and we come up with “Fliegerbenzin”, a fuel mixed with benzol. We have a summer variant with 60% benzol and a winter variant with 50% benzol for a lower freezing point for high altitude operations in the winter month.

 

Engineers: Theoretically “Fliegerbenzin” also enhances performance with the high altitude engines at lower altitudes because of the higher octane rating and therefore higher knocking resistance of the benzol.

 

Mercedes: We could make use of the Fliegerbenzin if we go back to the old carburator of our previous engine block the IIIa, of which we have plenty lying around in “den Ersatzteillagern”. The beauty of never having developed another engine block is that everything from the previous engines will fit.

 

BMW: You can run our high altitude engine even with pure benzol since late 1917 with no issues minus a bit of power and you don’t need to change the carburator at all.

 

KoGenLuft: Is there nothing we could possibly do to keep our aircrafts fuelled? What is with that Fliegerbenzin they are all mumbleing about?

 

OHL: Oh, that? Nah, *stretches* probably not going to happen. Anyways the Bratwursts are ready anyone up for it?

 

And now I am back to cherry picking....

 

Sizzlorr out...

Edited February 13, 2023 by J99_Sizzlorr

[BMA_Hellbender]

Petrol and benzol production aside, the industry we know for sure flourished from late 1917 onwards thanks to German aviation is silk.

[J2_Trupobaw]

On 2/12/2023 at 11:25 PM, US103_Rummell said:

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!

 

0. Can we keep the egos out of this discussion, please?

1. There is none AFAIR. The Germans themselves consiedered D.IIIa / D.IIIau upgrades of D.III rather than separate models; the distinction is more present in historians discussions than among German mechanics. To them, it was Mercedes D.III with all/some most recent upgrades. Since all "variants" used the same engine block, they all had "Mercedes D.III" stamped on it, confusing the Entente captors further; captured planes were quickly classified as running 180 hp or even 160hp Mercedes. It's thanks to  German sources being lost/destroyed  and Entente being quick and dirty look on captured plane that we have things like 180hp D.Va and D.VII in mod-1918 game; it's going on since 2009.

It's like asking for evidence that most NVIDIA using v-pilots have upgraded their GTX 10X0-GTX 20X0 to 30X0 or 40X0 by 2023. We know nobody wants to be stuck with older card now that they are cheaper, but try getting hard numbers by looking at PC boxes and hearing us boasting about computer performance!

As of the late-war "standard" - every engine was taken to Flugpark for complete overhaul every few months / number of flying hours. Same for engines recovered from wrecks. This included upgrades with newer pistons, carburettor etc if available and approperiate.

I don't have hard numbers on how often overhaul happened  in mind, but there is plenty discussion on Merceded variants on http://www.theaerodrome.com/ that could be quickly googled last time I looked. But AFAIR by the summer 1918 the last engine blocks, ones bult/overhauled just before 200hp upgrades were introduced,  would finally be overhauled. No engine had right to run this long without being sent to Flugpark. 

2,3,4 - Pilot anecdotes are just that. If we start believing everything Goering said, we may as well start believing combat claims of Billy Bishop and start practicing our Plankturns. What we can do is ask engineers like @Holtzauge and people actually running the engine in question if this kind of performance is possible / plausible. Ideally, take an engine to Aeroengine test facility and check the real performances at various altitudes (I can't believe it has not been done?). Then we should look into history for evidence to the contrary. If there is none, we get to assume it's something that might happen ... which is the best we can hope for, anyway. 

Now, back to the Earth, we are playing the game where 180hp Albies, weird underpowered Dreideckers, <trigger> DFW with 1916 engines </trigger>  and Viper S.E.5as share the same sky. While every other Halberstadt has high-altitude engine for ground attack, and a Becker in the back. While the history can not be 100% pinpointed anymore, there is a lot of room to make what we have more historically plausible, and, frankly, more real. If we got down just to having only things that might happen I'd be a happy panda.

Edited February 28, 2023 by J2_Trupobaw

[No.23_Starling]

10 hours ago, J2_Trupobaw said:

0. Can we keep the egos out of this discussion, please?

1. There is none AFAIR. The Germans themselves consiedered D.IIIa / D.IIIau upgrades of D.III rather than separate models; the distinction is more present in historians discussions than among German mechanics. To them, it was Mercedes D.III with all/some most recent upgrades. Since all "variants" used the same engine block, they all had "Mercedes D.III" stamped on it, confusing the Entente captors further; captured planes were quickly classified as running 180 hp or even 160hp Mercedes. It's thanks to  German sources being lost/destroyed  and Entente being quick and dirty look on captured plane that we have things like 180hp D.Va and D.VII in mod-1918 game; it's going on since 2009.

It's like asking for evidence that most NVIDIA using v-pilots have upgraded their GTX 10X0-GTX 20X0 to 30X0 or 40X0 by 2023. We know nobody wants to be stuck with older card now that they are cheaper, but try getting hard numbers by looking at PC boxes and hearing us boasting about computer performance!

As of the late-war "standard" - every engine was taken to Flugpark for complete overhaul every few months / number of flying hours. Same for engines recovered from wrecks. This included upgrades with newer pistons, carburettor etc if available and approperiate.

I don't have hard numbers on how often overhaul happened  in mind, but there is plenty discussion on Merceded variants on http://www.theaerodrome.com/ that could be quickly googled last time I looked. But AFAIR by the summer 1918 the last engine blocks, ones bult/overhauled just before 200hp upgrades were introduced,  would finally be overhauled. No engine had right to run this long without being sent to Flugpark. 

2,3,4 - Pilot anecdotes are just that. If we start believing everything Goering said, we may as well start believing combat claims of Billy Bishop and start practicing our Plankturns. What we can do is ask engineers like @Holtzauge and people actually running the engine in question if this kind of performance is possible / plausible. Ideally, take an engine to Aeroengine test facility and check the real performances at various altitudes (I can't believe it has not been done?). Then we should look into history for evidence to the contrary. If there is none, we get to assume it's something that might happen ... which is the best we can hope for, anyway. 

Now, back to the Earth, we are playing the game where 180hp Albies, weird underpowered Dreideckers, <trigger> DFW with 1916 engines </trigger>  and Viper S.E.5as share the same sky. While every other Halberstadt has high-altitude engine for ground attack, and a Becker in the back. While the history can not be 100% pinpointed anymore, there is a lot of room to make what we have more historically plausible, and, frankly, more real. If we got down just to having only things that might happen I'd be a happy panda.

You should buy Holtze's book - I think you'd really enjoy both the history (including German and Allied sources) and the detailed engineering. I've never read anything like it in our wee corner of history.

 

As you say, Goering is to be taken with a pinch of salt. If you have the DVII Aces book from Osprey you'll notice a letter from Lothar v Richthofen printed right after the Goering quote - written just days later - giving very clear and strict instruction to his pilots on the usage of the new engine which directly contradicts the former's letter.

 

NB, just be careful on the Viper SE5a as you suggest it was materially different to the HS versions. I've got several sources which show a slight improvement in speed and climb at alt above where most multiplayer action occurs, but otherwise the 200hp HS8B (also built under license) had similar performance - see Guttman in SE5a vs DVa for data. Both output 200hp nominal, with the Viper (basically a HS8Ab built under license) coming in around 70lb lighter according to Alec Lumsden which might give a clue to the slight increase in speed and climb rate, though according to Lumsden the British also gave their HS8B engines the 220hp upgrade and I dont have test data for the upgraded HS8B, only the lower compression version. McCudden did this himself to his SE5a HS8B 4 prop, supposedly securing the high compression pistons from the French directly. He did this, alongside altering the dihedral and cutting back his exhaust pipes to improve high-alt performance in order to catch the high 2-seaters.

 

The 4 and 2 blade props appeared on all variants and you can see this in photos, but the only difference in performance I can find is a reference to the 2 blade causing less torque and therefore less adverse yaw (see Mount of Aces); as Holtz will tell you in his book, the pitch of the prop would impact things like climb and speed, and generally we see evidence of British pitching being for speed vs German for climb. The engineering evidence does not suggest there was ever a 'turning' SE5a, with the main advantage of the Viper being that it was just an upgraded HS8Ab built under license, which had direct drive and therefore solved the major issue of the engine gearing breakdowns. Remember all the issues with the SPAD XIII you read about in sources? That's why the French kept their SPAD VIIs right up till Nov 1918 - the HS8Ab (basically the Viper) didnt keep failing!

 

If you have data or engineering rationale to suggest there was a substantial performance difference between the Viper and the HS200/220hp versions then do share, otherwise I thoroughly recommend you read Holtze's chapter on turn performance ?

 

S!

[VeltroRoF]

On 10/20/2022 at 11:13 AM, Holtzauge said:

Yes, I model the propellers thrust depending on the rpm, diameter, pitch and so-called "solidity". The solidity is basically how much blade area you have (could be distributed over 2 or 4 blades) which in turn determines how "loaded" the individual propeller blades get, which in turn determines it's efficiency. This (the modeling of propeller efficiency) is covered in a short chapter in the book and also discussed in the dive chapter where it is explained how the propeller goes from producing thrust to causing extra drag by windmilling which of course also needs to be modeled.

 

Dear Holzauge,

 

Since there was so much discussion regards to engine and propeller performance already years back (and also now again in this thread) in Aug 2021 I did make an attempt to make a calculation sheet to be able to calculate the performance of a propeller and verify them against engine performance. I literately spend hundreds of hours on it. The calculation are based on Blade Element Theory and Blade Element Momentum theory. Looking at what you said above, it seems you may have done a similar thing.
 

Eventually I never posted anything about it since I can't verify if the calculations are correct and do not have the correct airfoil data for the propellers and can only calculate with the same propeller airfoil and apply it on different measurements of different propellers. I found propellers on the internet and manually measuring them. Also I still have some issues to understand the prandtl tip-loss factor. Problem is that when I attempt to use the tip-loss factor the calculated RPM's go up and this is counter intuitive for me, I think it should go down. So I think at that point the calculations are not correct and I cannot use that correction.

 

Regards to the discussion above an engine performance the calculations that I made suggest that if indeed higher engine power can be expected, then there should also be propellers that match this. I wonder if you made the same conclusion. Regards to the propeller, I have not been able to find anything bigger/thicker propeller as the AXIAL 19904 (second link below) for the matching airplane which has the marking 200PS and my calculation shows it would run above 1600 rpm at 197HP. More engine power, then it would probably run too fast for the engine since the max would be 1600 right. But again, there is an error margin since I do not have the correct airfoil data for the prop.
AXIAL 19904: http://woodenpropeller.com/DVII.html

 

Anyways, I would be totally happy to setup a video conference meeting with you to compare notes and show you what I found if you are interested.

 

With best regards,
Veltro (sorry guys, not been flying for a long time, too busy in RL)

[Holtzauge]

3 hours ago, VeltroRoF said:

 

Dear Holzauge,

 

Since there was so much discussion regards to engine and propeller performance already years back (and also now again in this thread) in Aug 2021 I did make an attempt to make a calculation sheet to be able to calculate the performance of a propeller and verify them against engine performance. I literately spend hundreds of hours on it. The calculation are based on Blade Element Theory and Blade Element Momentum theory. Looking at what you said above, it seems you may have done a similar thing.
 

Eventually I never posted anything about it since I can't verify if the calculations are correct and do not have the correct airfoil data for the propellers and can only calculate with the same propeller airfoil and apply it on different measurements of different propellers. I found propellers on the internet and manually measuring them. Also I still have some issues to understand the prandtl tip-loss factor. Problem is that when I attempt to use the tip-loss factor the calculated RPM's go up and this is counter intuitive for me, I think it should go down. So I think at that point the calculations are not correct and I cannot use that correction.

 

Regards to the discussion above an engine performance the calculations that I made suggest that if indeed higher engine power can be expected, then there should also be propellers that match this. I wonder if you made the same conclusion. Regards to the propeller, I have not been able to find anything bigger/thicker propeller as the AXIAL 19904 (second link below) for the matching airplane which has the marking 200PS and my calculation shows it would run above 1600 rpm at 197HP. More engine power, then it would probably run too fast for the engine since the max would be 1600 right. But again, there is an error margin since I do not have the correct airfoil data for the prop.
AXIAL 19904: http://woodenpropeller.com/DVII.html

 

Anyways, I would be totally happy to setup a video conference meeting with you to compare notes and show you what I found if you are interested.

 

With best regards,
Veltro (sorry guys, not been flying for a long time, too busy in RL)

 

The work you have spent on blade element theory sounds very interesting and something I would very much like to hear more about. You can contact me via this page.

 

In my simulation model I do not use blade element theory but rely on experimental data. NACA has done extensive work on this and I use different propeller models for WW2 and WW1 aircraft. For WW2 aircraft I use modeling based on something NACA calls the propeller speed coefficient Cs while for WW1 aircraft I model based in the propellers advance ratio J. If you are interested, there are many NACA reports on both methods but for the former I recommend NACA report 642 and for the latter NACA report 141. They can be downloaded via many sites but the NASA NTRS server is a good source:

 

NACA report 642.

 

NACA report 141.

 

Regarding the exact horsepower German WW1 engines actually put out and how they are rated can at times be confusing. But the BMW IIIa would probably put out in the order of 185 hp in ordinary climb conditions up to the full throttle height. However, if you take the tangent of the power/altitude curve it will cross the y-axis at around 240 hp at 1400 rpm and this theoretical value is sometimes called its "Spitzenleistung". However, BMW's own user manual refers to it as a 185 hp engine based on its power at the FTH. So in that sense maybe you should not take the exact 200 hp to literally.

Anyway, I would be very interested to hear about your work with blade element theory so please do contact me via the contact form I linked above!