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Ze_Hairy

BoS fighters roll comparison

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1455992359-bos-fighters-roll.png

 

Calculated with a simple stopwatch after that i've recorded with Fraps (hello the experts, the objective is not to be 100% accurate here but to have a not-too-bad idea, nothing else).

 

I tested the La-5 too but it's useless to add it in the chart since his roll rate is really close (if not the same) to that of LaGG-3. Same story for Bf 109G-2.

 

Fw 190 was tested w/o outboard cannons

 

Now let's talk seriously... Does anyone here has data to share about Bf 109F/G roll rate ?

 

I only know this (DVL evaluation): http://bbs.hitechcreations.com/smf/index.php?topic=160997.0 (the image is gone, sadly)

 

Max roll rate of Bf 109F-2, at 30kg/66lbs stickforce :

200 kph = 45 deg/sec (0.8rad)
300 kph = 68 deg/sec (1.2rad)
400 kph = 83 deg/sec (1.45rad)
480 kph = 20kg/44lbs limit
500 kph = 88 deg/sec (1.55rad)
600 kph = 91 deg/sec (1.6rad) - peak value
700 kph = 56 deg/sec (0.98rad)
800 kph = 23 deg/sec (0.4rad)

 

(speed is TAS, and altitude is 3000m)

 

EDIT: New chart

Edited by Ze_Hairy
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Now let's talk seriously... Does anyone here has data to share about Bf 109F/G roll rate ?

 

 

Russians seem to have, I know what is the typical attitude of community towards their testing but after briefly going through this report it is extremely detailed and could possibly give a lot of info we are looking for :  

http://www.wwiiaircraftperformance.org/me109/Me-109_G2_14513_Russian.pdf

 

This graph for example presents https://i.gyazo.com/b0a833a1b78a8fe0efd0f3bb7abc83ec.png forcess necessary to deflect the elevator. 

 

Here are important ones for us :

https://i.gyazo.com/fa546c24233b7ea6732b6593ff330dd5.png

https://i.gyazo.com/20894d6db1efd29fa3695928b3476abf.png- force required to get a roll rate of 1 radian/second

https://i.gyazo.com/28b1f269c0b9ab347098dc50179c8862.png- wx/d(el) which I assume is degree of aileron deflection, and wx is supposed to be roll rate but the number I get doesnt make sense. 

I think you should ask Sokol or someone else who can translate it properly, I might be wrong here. One thing I noticed is that it shows that Yak-9 and Yak-7 require less force for the deflection. 

 

Ps. I approached Nabutso with this, that document doesnt seem to be that easy to translate it seems. 

Edited by =LD=Hiromachi
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Russians seem to have, I know what is the typical attitude of community towards their testing but after briefly going through this report it is extremely detailed and could possibly give a lot of info we are looking for :  

http://www.wwiiaircraftperformance.org/me109/Me-109_G2_14513_Russian.pdf

 

This graph for example presents https://i.gyazo.com/b0a833a1b78a8fe0efd0f3bb7abc83ec.png forcess necessary to deflect the elevator. 

 

Here are important ones for us :

https://i.gyazo.com/fa546c24233b7ea6732b6593ff330dd5.png

https://i.gyazo.com/20894d6db1efd29fa3695928b3476abf.png- force required to get a roll rate of 1 radian/second

https://i.gyazo.com/28b1f269c0b9ab347098dc50179c8862.png- wx/d(el) which I assume is degree of aileron deflection, and wx is supposed to be roll rate but the number I get doesnt make sense. 

I think you should ask Sokol or someone else who can translate it properly, I might be wrong here. One thing I noticed is that it shows that Yak-9 and Yak-7 require less force for the deflection. 

 

Ps. I approached Nabutso with this, that document doesnt seem to be that easy to translate it seems. 

 

Thx Hiromachi.

 

Yeah we definitely need a Russian translator to know what each of these charts represent.

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Here, initial.

 

Ok copy. Guess in real life the 190 had a way bigger advantage over the Lavochkin aircraft due to the very light control forces, but since those are not modeled in BoS, i guess we have to accept it how it is..

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Ok copy. Guess in real life the 190 had a way bigger advantage over the Lavochkin aircraft due to the very light control forces

 
Or simply due to the fact that LaGG-3 s.29 (and La-5 s.8) roll rate is wrong/exaggerated in BoS. The same for Bf 109s... 120°/s peak lolz, and look at the ridiculous difference with Fw 190 at high speed, then takes a look at DVL results (30kg/66lbs !!).
 
500 kph = 88 deg/sec (1.55rad) = 430km/h CAS
600 kph = 91 deg/sec (1.6rad) - peak value = 520km/h CAS
700 kph = 56 deg/sec (0.98rad) = 610km/h CAS
800 kph = 23 deg/sec (0.4rad) = 700km/h CAS
 
In BoS, at max deflection, Bf 109s do more than 50°/s at 700km/h CAS... 
Edited by Ze_Hairy
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Or simply due to the fact that LaGG-3 s.29 (and La-5 s.8) roll rate is wrong/exaggerated in BoS. The same for Bf 109s... 120°/s peak lolz, and look at the ridiculous difference with Fw 190 at high speed, then takes a look at DVL results (30kg/66lbs !!).
 
500 kph = 88 deg/sec (1.55rad) = 430km/h CAS
600 kph = 91 deg/sec (1.6rad) - peak value = 520km/h CAS
700 kph = 56 deg/sec (0.98rad) = 610km/h CAS
800 kph = 23 deg/sec (0.4rad) = 700km/h CAS
 
In BoS, at max deflection, Bf 109s do more than 50°/s at 700km/h CAS... 

 

 

 

The only measured data point I know of for Lavochkins is the La-5FN the Germans measured peak roll rate at ~90 degrees a second.  

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La-5FN is not representatife for La-5 1942 performence though due to changed aileroun layout. Roll rate and manouvrebility where among the most important improvements that came with the FN version.

Edited by Stab/JG26_5tuka

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I do not know enough about it to say.  I defer to your expertise on this one.

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La-5FN is not representatife for La-5 1942 performence though due to changed aileroun layout. Roll rate and manouvrebility where among the most important improvements that came with the FN version.

Do you have any data for aileron reversal speeds on any of the Russian fighters, La, Lagg or Yak? This has a big impact on roll rate at high speeds and I'm very interested in these numbers since I suspect that they will be lower than for the German planes due to the wooden veneer used in the wing covering.

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Sry, I have no hard data on La-5 roll rate. Searched for that (and Lagg-3, too) for long time but have not been sucesfull so far.

Edited by Stab/JG26_5tuka

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Ok, well I suspect this may be one reasons for a lower Vne for the Russian planes: While I admire the way the Russians used wood in the structure of planes, it still must have been a challenge to build a torsionally stiff wing given wood's lower Young modulus.

 

In fact would be nice to see some data on this because I suspect that the Russian planes with plywood covered wings were quite limited in roll at higher IAS for just this reason........

Edited by Holtzauge

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Ok, well I suspect this may be one reasons for a lower Vne for the Russian planes: While I admire the way the Russians used wood in the structure of planes,sionally stiff w it still must have been a challenge to build a toring given wood's lower Young modulus.

 

In fact would be nice to see some data on this because I suspect that the Russian planes with plywood covered wings were quite limited in roll at higher IAS for just this reason........

 

[Edited]

Edited by Bearcat

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What's discrediting here? The lower Young modulus? The lower vne the Soviet planes got? That many of their wings were made of wood? The curiosity about aileron reversal speeds? The idea that all this may be connected?

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[Edited]

Only one discrediting someone, is you Dakpilot - again, and again, and again. Anytime, someone says something, that could show some Soviet tech in a slightly bad light, you jump on them and try to discredit them. [Edited]

Edited by Bearcat
Let's not straddle any lines here....
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I don't think wood is a solely Russian tech :) I have no agenda

 

Cheers Dakpilot 

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I don't think wood is a solely Russian tech :) I have no agenda

 

Cheers Dakpilot 

Can you name any other fighters made of wood that saw front line service?

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[Edited]

 

 

That was not called for, and you do not speak for anyone but yourself. Keep out this conspiracy BS and read the post twice before you attack people

Can you name any other fighters made of wood that saw front line service?

I can name one of the most successful ones the Mosquito. Germans tried to copy it but their glue factory was hit and well they failed in the attempt making new. 

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I can name one of the most successful ones the Mosquito. Germans tried to copy it but their glue factory was hit and well they failed in the attempt making new. 

But the Mossie started as a bomber not a fighter. It also used a different construction than the Soviet fighters.

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My comment was intended not as an insult, merely a humorous dig at the 'maligning' of wooden aircraft which I know Holtzauge was not really intending

 

It is interesting that the aircraft that completed the most bombing raids in WWII, 213 sorties (by a single aircraft), an incredible feat, was a wooden Mosquito 'F' for Freddy (true as far as I know)

 

If anyone is interested, Design of wood aircraft structures by U.S. Army Navy committee 1944 is a good read on the science/testing of wood from that era, and from  Wood to metal : the structures of modern aircraft design Peter. L. Jakab says it better than me

 

"What does this brief bit of aerospace history tell us? Beyond illustrating
a few of the salient technical elements of the origins of metal
aircraft construction, the story also suggests an interesting cultural
insight regarding materials and engineering design. Namely, ostensible notions of what is modern and what is outdated sometimes can
be masked and confused if we only consider the material, and not
the design concept independent of the material. In assessing tech- nology during the twentieth century, wood typically has been seen
as old and regressive and metal as new and progressive. In the case of aeronautics, however, these concepts often mixed and merged
in interesting and complex ways. A seemingly antiquated wooden
airplane, from a structural design perspective, in some respects may
have been just as modern and revolutionary as a newer-lookingmetal one. This teaches us that we must sometimes look beyond acquired
prejudices regarding materials when making assessments of what is new and innovative. "
 
Cheers Dakpilot

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It is interesting that the aircraft that completed the most bombing raids in WWII, 213 sorties (by a single aircraft), an incredible feat, was a wooden Mosquito 'F' for Freddy
 

Very meaningful. A Mossie has to withstand very high G-forces and huge divespeed every sortie..oh wait

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Can you name any other fighters made of wood that saw front line service?

 

Although it did not have a very auspicious service and was rather underpowered the French Caudron C.714 did see a bit of frontline service with 12 confirmed kills five Bf110 four Do17 and 3 Bf109

 

probably not the finest example for my defense of wooden aircraft   :biggrin:

 

 

 

But the Mossie started as a bomber not a fighter. It also used a different construction than the Soviet fighters.

 

The second prototype that flew, was the pure day fighter variant F II No. 4502. differing in having a side door, joystick instead of yoke and stronger wing spar, so it is reasonably fair to say that it did have a fighter variant from the start

 

Although I fear I am derailing the topic which should be about roll rates  ;)

 

Cheers Dakpilot

Edited by Dakpilot

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OT

Main wing on Yak was not made from just "wood".Maybe someone thinks of it like you chop a tree and then you shape it with axe into main wing spar :)  

Its a bit more complicated.It was in fact composite construction.Main spar was made from 4 pieces of pinewood+intersecting rectangle-like ribs joining upper 2plyed glued pinewood part with lower 2plyed pinewood part+front and rear plywood layer to give it final "box-like" look.All glued together.It created a rigid yet reasonably lightened construction.

The aim of this construction was to get equal properties comparing to metal design.The dawnfall was the increased weight of such construction,of course.

 Flaps were "Frise" type,made of duraluminium covered with linen.

end of OT

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Sorry if I stirred up the pot and maybe I was not sufficiently clear when I asked the question but I am genuinely interested in the aileron reversal speed for WW2 wooden winged planes. OTOH, maybe the reason for the lower Vne in the Russian fighters was flutter or some other issue? Still, if it was aileron reversal then this certainly affects roll performance so it would be good to know more.

 

Also, to clear thing up:  I am I no way saying that Russian design practices were poor because they used wood. In fact wood is as has been pointed out above an excellent material to build airplanes in: it has very good fatigue properties, good strength to weight ratio, can be used in different densities from balsa to birch and pine, compressed and laminated into veneer plywood etc. etc.  In addition, the Germans evaluated the wood materials used by the Russians in WW2 and IIRC they said it was just as good as their own. Also, let's not forget the German wooden props on the late Fw-190's and Ta-152's ;)

 

However, there is no going around the low Young modulus and that this will result in more flexing in a wooden structure than an aluminum one unless you horrendously over-dimension the structure which I don’t think the Russians did. In fact this would also be interesting to understand: Were the Russian fighters structurally dimensioned more with flexing in mind than absolute strength?

 

Maybe some kind person with knowledge in Russian could post these questions in the Russian forum? I mean why the lower Vne? Was it due to aileron reversal, flutter or some other issue? Were the wings designed for ultimate strength or to avoid excessive torsion or bending?

 

Finally, I have only the highest respect for Russian aeronautical engineering: In fact, I worked for more than 10 years in the Swedish aviation industry on systems for the Viggen and Gripen and I can tell you we certainly took systems like the Su-27 and S-300 very seriously. :cool:

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we certainly took systems like the Su-27 and S-300 very seriously.

 

 

 

[Edited]

Edited by Bearcat

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Hi Holzauge,

Your question is very interesting and in same time very specific.To have some answers would require access to archive materials of CAGI and CAMO,at least,which is quite difficult,but not impossible.But its smtg for the dedicated researcher rather than ordinary hobbist.

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In basic premise, wood is not as torsionally stiff and the resulting structure to reach equivalent torsional stiffness would have to be heavier than other materials.  Holtzauge is correct in his observation.

 

But at the same time "wood" is only part of the laminate technology the Russians used as I understand it.  Like the German propellers, that is more a composite material and as such does not have the same properties.

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Hi Holzauge,

Your question is very interesting and in same time very specific.To have some answers would require access to archive materials of CAGI and CAMO,at least,which is quite difficult,but not impossible.But its smtg for the dedicated researcher rather than ordinary hobbist.

Ok, I guess that it would require a visit in person? BTW I'm not familiar with the abbreviations, what are CAGI and CAMO?

 

Again, maybe someone in the Russian forum may know the answer?

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Are you implying I'm lying about being an aeronautical engineer?

 

Well not at all, but I find it curious that despite being an aeronautical engineer, 10 years at SAAB et all, and you never heard of the largest Russian aeronautical institute just next door, that's being around for almost a hundred years.

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Well not at all, but I find it curious that despite being an aeronautical engineer, 10 years at SAAB et all, and you never heard of the largest Russian aeronautical institute just next door, that's being around for almost a hundred years.

Well you did link to TsAGI:  http://www.tsagi.com/  and I have to confess I did not make the connection that TsAGI was CAGI or was it  CAMO?

 

So glad we cleared up that other piece of verbal miscommunication: You see for a moment there I thought you were actually implying that I lied but apparently it turned out to be just "curiosity". How cute!

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Well not at all, but I find it curious that despite being an aeronautical engineer, 10 years at SAAB et all, and you never heard of the largest Russian aeronautical institute just next door, that's being around for almost a hundred years.

 

 

[Edited]

Edited by Bearcat

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Sorry,my bad.In English "phonetics" it is usually written as TsAGI where "Ts" stand for Russian "C" which has completely different letter in written azbuka "Ц":)

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Sorry,my bad.In English "phonetics" it is usually written as TsAGI where "Ts" stand for Russian "C" which has completely different letter in written azbuka "Ц":)

Ok, no problem. I asked about the abbreviations and you replied so I'm with you now. Since you seem so well versed in Russian maybe you can ask them the questions I listed above? :) 

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