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Test roll rate fw 190A3 Bf109F4 La5 LaGG3

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7 hours ago, Panthera said:

Having ailerons spanning all the way out to the tip of the wings like on the 190 also helps with roll rate.

 

This again helps with roll acceleration, but not with maximum roll rate. Depending on the size of the ailerons, the best position of the outside edge of the ailerons for maximum roll rate appears to vary around the 90% point on the wing. Reason for this is that when the plane is rolling, the outside parts of the wing reach a higher angle of attack than the inside parts, thereby reducing the angle of attack of the aileron, thereby reducing effectiveness. Below a chart from the NACA report Summary of lateral control research, which summarizes the empirical results for this. I have added three lines for different lengths of ailerons (percent of wing span) and as you can see, going all the way to the wing tip does not produce the best results for maximum rolling performance (the higher the value gamma', the higher the rolling performance, linear relationship).

 

bla008.jpg.42b0cc19039fec98ccc8791a85da8dea.jpg

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Posted (edited)

S!

 

 If La-5 series would have been such awesome rolling planes we surely would know about it. But not a single posted report supports this claim nor ones I have read over the years. On the contrary most of them(russian ones) say control forces were heavy hampering maneuverability in LagG-3 to improved in La-5F and a bit better in La-5FN.  The quote from the book above says La-5FN rolled some 90deg/s at 400km/h so about 4sec. From Finnish test reports on the Bf109G-2 in 1943 it rolled 360deg in 4-5sec at speeds of 400-450km/h, without rudder assist. So pretty well corresponds with the Rechlin test on La-5FN by Germans. And also the interviews with veterans saying that the only VVS plane having an advantage over Bf109G in roll was Yak. It could initiate and do a faster roll than Bf109G at speed. Am I misunderstasnding something here? :P

Edited by LLv34_Flanker

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Posted (edited)
4 minutes ago, LLv34_Flanker said:

Am I misunderstasnding something here? :P

 

Different reports from different tests, with unknown determining factors (initial roll, sustained roll etc. pp.) with partly different planes than what we're talking about, generously extrapolated because of... ?? ..., all of this from various sources... and this compares exactly how?

Am I missing something here? :P

 

Cheers!

Mike

Edited by SAS_Storebror
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Is there any chance that we could see the source documents that were used in LA5 roll rate determination in game development? 

 

Ed. 

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Posted (edited)
29 minutes ago, MK_RED13 said:

Is there any chance that we could see the source documents that were used in LA5 roll rate determination in game development? 

 

Ed. 

 

I believe not - expensively sourced research etc, I seem to recall being the reasons. Which is a shame: I am sure some of our engineer experts would love to have a look and might even have a productive discussion with the developers.

 

I do not think, however, that if they did publish said documents - assuming that they exist - it would resolve the controversy completely when there are people in this community who seem seriously to believe that only hours spent in MP qualify anyone to have an opinion on these topics. And that is ignoring the mouth-breathers who feel the need to send abusive PMs.  After all these are Russian documents and therefore intrinsically untrustworthy, unlike  German documents.

Edited by unreasonable
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7 minutes ago, unreasonable said:

 And that is ignoring the mouth-breathers who feel the need to send abusive PMs.  

 

unreasonable if you're getting abusive, unsolicited PMs then publish them here so we can all make a judgement on the character of these people.

The PM system is most certainly not provided here for certain members to try and abuse and intimidate others.

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47 minutes ago, LLv34_Flanker said:

The quote from the book above says La-5FN rolled some 90deg/s at 400km/h so about 4sec.

What it actually says:

"The machine has been in service for some time."

"Aileron effectiveness is outstanding."

"At 450km/h indicated a roll takes barely four seconds."

"At 600km/h indicated the forces become high."

"Aileron effectiveness is better than that of the Bf109."

Stalling:

"At 210 to 200 indicated the slats extend and aileron forces become light to the point of over-balance."

"In a steep turn with power aileron over-balance appears much more pronounced and occurs at rather high airspeeds..."

"...the condition is not pleasant when one is forced to make sharp aileron movements; the stick then has a tendency to move right to one side."

 

What it doesn't say:

Detailed condition of the aircraft and ailerons tested.

Conditions like altitude or control forces for the roll test.

Description of the test procedure - one roll or sustained rolling, start stop when, measured how?

Exact results.

Interpretation of the results - what is the maximum obtainable?

Relation to Fw190.

 

All in all, I consider the handling information much more relevant than the performance information. I'd love to see things like that in game. Not just for the La, though.

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Posted (edited)

Summing up it looks like the best evidence points to a roll rate of about 110 deg/s just as LLv34_Flanker is saying:

 

Using the German figure for a 360 deg roll of 4 s at Va=450 Km/h this equates to an average of 90 deg/s for the La-5. However, as has been pointed out above, this underestimates the stationary roll rate since it includes the roll acceleration phase as well.

 

So, in order to make it comparable to the NACA chart, we need to estimate the effects of the acceleration. As an optimistic estimate, assume that the full rate is achieved after 1 s. Assuming a linear acceleration phase this means that the stationary roll rate will be approximately 100 deg/s.

 

As a pessimistic estimate, assume that the full rate is achieved after only after half the time, i.e. 2 s. Again assuming a linear acceleration phase this means that the stationary roll rate will be approximately 120 deg/s.

 

So this means that the La-5 stationary roll speed is in the order of 100-120 deg/s at Va=450 Km/h. Comparing this we have the Fw-190 coming in at 145 deg/s at the same speed in the NACA chart.

 

So it looks like the La-5 is a good performer in roll, much better than the Me-109 but not quite up to the standard set by the Fw-190…….

 

16 minutes ago, JtD said:

What it actually says:

"The machine has been in service for some time."

"Aileron effectiveness is outstanding."

"At 450km/h indicated a roll takes barely four seconds."

"At 600km/h indicated the forces become high."

"Aileron effectiveness is better than that of the Bf109."

Stalling:

"At 210 to 200 indicated the slats extend and aileron forces become light to the point of over-balance."

"In a steep turn with power aileron over-balance appears much more pronounced and occurs at rather high airspeeds..."

"...the condition is not pleasant when one is forced to make sharp aileron movements; the stick then has a tendency to move right to one side."

 

What it doesn't say:

Detailed condition of the aircraft and ailerons tested.

Conditions like altitude or control forces for the roll test.

Description of the test procedure - one roll or sustained rolling, start stop when, measured how?

Exact results.

Interpretation of the results - what is the maximum obtainable?

Relation to Fw190.

 

All in all, I consider the handling information much more relevant than the performance information. I'd love to see things like that in game. Not just for the La, though.

 

OK, so this is the fallback  position? The data we have does not agree with my opinion so then question the condition of the aircraft and test conditions? Well it may well have been a lemon the Germans tested or OTOH it may actually have been better than average. Maybe the Germans doing the test were incompetent and used a different test procedure making comparison to their own aircraft impossible. We simply don't know. The only thing we do know is that we have the data I used above to do an estimate which AFAIK is the best data available which actually means that the ball is back in the "the La-5 was superior to the Fw-190 in roll" part of the court. So please, those who think the La-5 rolled better than the Fw-190, where is the data?

Edited by Holtzauge
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26 minutes ago, Holtzauge said:

the best evidence

Make that "one of the many possible interpretations" and I fully agree.

Evidence is what's missing here all the time.

 

Cheers!

Mike

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28 minutes ago, Holtzauge said:

The data we have does not agree with my opinion so then question the condition of the aircraft and test conditions?

 

Well, my opinion is the Fw190 rolled better than the La-5. I'm just refusing to supplement missing data with assumption, because then data becomes opinion and that's what I already got.

...

If the roll was done at sea level, you need to add 15% to your figures, if it was done at 6km, you need to subtract 15%. The line before the roll he's referencing 2000m, what makes you think the roll was performed at 3km?

The same is true for forces - as long as you don't know if he used 10, 20 or 30 kg of stick force or he just applied what he felt would be good, how can you compare it to NACA data? NACA did it with 50lb force, the German tested the Bf109 to 30kg, quite a bit higher. Not comparable. At least not necessarily so.

How were the forces measured, how was the roll rate measured - if at all? Maybe he just did a quick roll and looked at his watch. That's totally within the standard procedures of the day and completely satisfies the purpose of this test, but it makes it incomparable to NACA data.

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Posted (edited)

So if you guys are so unhappy with this why don't you go out there and find some better data? Honestly, I find this refusal to use the data we have and find excuses because it does not fit the modeling we have in-game funny. But I'm sure the same scrutiny and questioning of the Rechlin data would have been applied if the Rechlin test had said 2-2.5 s instead of 4 s right? Since the test conditions were not detailed then this data would not have be used as proof that the La-5 rolled better than the Fw-190? No way this would have been used by by some forum members to "prove" that the devs had nailed the La-5 modeling? Seriously? :lol:

Edited by Holtzauge
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I find it annoying that time and again you're implying an agenda. If you read what I wrote you'd realize that I'm critically assessing known data, because the in game situation does not mirror my expectations. It's not my fault that the La-5 has an extremely effective aileron layout or that the sole known test data point comes with lots of uncertainties.

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Posted (edited)
1 hour ago, JtD said:

I find it annoying that time and again you're implying an agenda. If you read what I wrote you'd realize that I'm critically assessing known data, because the in game situation does not mirror my expectations. It's not my fault that the La-5 has an extremely effective aileron layout or that the sole known test data point comes with lots of uncertainties.

 

I think, that it's not right to blame you with anything. You've written in this thread many reasonable details, "Why the La-5 could be OK". I also like your well ballanced "engineering-scepticism" and also level of detail, which are you mentioning (e.g. WHY there is difference between rolling here and there, WHY is important to have large airlons with good shape, or WHY aren't data from Rechlin and NACA comparable). Until this moment, it's great.

 

BUT: There are many historical evidences, where are witnesses saying: "Ok, La-5 was Ok and moreless comparable or maybe even a little better than 109", but there is no-one, which says: "It was The Great One". And as you know, the current implementation in game is saying: "Well, it was the best one". I know about effective design, which are you explaining here, but it's not confirmed in any (!) historicle memoir with any harder data. And that's no detail.

 

PS: I like your motto 😄

Edited by 1stCL/Fucida

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18 minutes ago, JtD said:

I find it annoying that time and again you're implying an agenda. If you read what I wrote you'd realize that I'm critically assessing known data, because the in game situation does not mirror my expectations. It's not my fault that the La-5 has an extremely effective aileron layout or that the sole known test data point comes with lots of uncertainties.

 

I'm not saying you have an agenda but I think you are being unneccessarily creative in trying to dismiss the data. Again, the Rechlin data is the only data we have and frankly I think the guys who did the tests can read a stopwatch.

 

In fact I got into this discussion only after you posted the below rosy view which I frankly don't agree with since it says we should be thankful that the developers did not base their roll modeling on the La-5's geometric layout. Here we simply have to agree to disagree for the reasons I outlined in my replies to this post above.

 

Also, in the below post you asked for data and both Flanker and I have provided that and the only numerical data we have so far hints that the La-5 roll rate is not better but worse than the Fw-190. So if someone want's to prove the opposite, the onus is on them to disprove the data on hand, not the other way around.

 

On 5/25/2018 at 5:55 PM, JtD said:

The excellent roll rate of the La comes from the geometry of the La's lateral control, which is superior to that of the Fw190. Smaller wing span, larger stick travel, larger aileron angles. No one needs detailed documentation to see that, it's very evident. And we're talking about advantages in the region of 50%, depending on circumstances.

 

I've said it before, the Fw190 ailerons were brilliant in terms of effectiveness, which, based on soft data and anecdotal evidence, more than offset the geometric advantages of the La. But until there's detailed data on the La available, we should at least note that the devs modelled the La ailerons with a considerably lower effectiveness, which puts the La roll rate in game into the realm of believable (yes, it does, believe it or not). If we think it's still optimistic, which I do, we need to find sources with hard, detailed data. In the meantime, we can still give the devs credit for not simply using geometry based data. I find ranting, occasionally bordering insulting, very unproductive and also unjustified.

 

Please look for data instead.

 

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11 hours ago, JtD said:

 

This again helps with roll acceleration, but not with maximum roll rate. Depending on the size of the ailerons, the best position of the outside edge of the ailerons for maximum roll rate appears to vary around the 90% point on the wing. Reason for this is that when the plane is rolling, the outside parts of the wing reach a higher angle of attack than the inside parts, thereby reducing the angle of attack of the aileron, thereby reducing effectiveness. Below a chart from the NACA report Summary of lateral control research, which summarizes the empirical results for this. I have added three lines for different lengths of ailerons (percent of wing span) and as you can see, going all the way to the wing tip does not produce the best results for maximum rolling performance (the higher the value gamma', the higher the rolling performance, linear relationship).

 

bla008.jpg.42b0cc19039fec98ccc8791a85da8dea.jpg

 

Well this is an odd one, but perhaps I misremembered. That said our example had a 60% aileron span.

 

Is it possible you could link the report?

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5 hours ago, Holtzauge said:

<snip>

 

Also, in the below post you asked for data and both Flanker and I have provided that and the only numerical data we have so far hints that the La-5 roll rate is not better but worse than the Fw-190. So if someone want's to prove the opposite, the onus is on them to disprove the data on hand, not the other way around.

 

 

 

Your interpretation of the presented data is entirely reasonable, it does hint that the La-5 roll rate is worse than the Fw 109's, ceteris paribus.  

 

But as far as I recall no-one so far in this thread has tried to disprove that hypothesis, or even for that matter say they think it is false: they have simply been saying that it cannot so far be conclusively confirmed or refuted with the data so far presented, for the reasons JtD outlined. 

 

So let us say that this data is suggestive that there is something odd about the relative roll rates, where do we take it in terms of the game?  All anyone can do is restate the comparison as clearly and logically as possible -  as you did - and PM Han. I assume someone who feels particularly strongly has already done that in the approved format some time ago.

 

The developers as usual, may or may not respond: they have said that they feel under no obligation to justify themselves every time someone questions FMs, as otherwise they would never get any work done.

 

As far as I am concerned it is not so much a matter of "trusting the developers" as recognizing that they have the power and we do not. If they say, or imply, that they have further data, that they trust, and that they are not sharing it, the only thing anyone can do about it is find some other data that helps clearly to prove that the game's interpretation is incorrect. This is the relevant onus of proof. People who either agree with the current interpretation or simply do not care do not have to prove anything.

 

If it is the case that there is simply no new data available to those of us without access to Soviet archives, then at some point we simply have to accept what we have. 

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On 5/28/2018 at 3:09 PM, JtD said:

 

Small related anecdote: The P-38 (initially) wasn't the best rolling aircraft, even when looking at peak rolling velocity. However, this was not a source for complaints. What it was abysmal at and what was complained about, however, was rolling acceleration.

 

I was quiet surprised how slow the roll acceleration and response was after looking at this footage. :o:

 

 

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14 hours ago, JtD said:

Well, my opinion is the Fw190 rolled better than the La-5.

I'm just refusing to supplement missing data with assumption, because then data becomes opinion and that's what I already got.

 

Exactly.

Precisely.

Thank you so much for putting the whole truth about these endless debates in just two sentences.

I'm subscribing each and every word of it.

 

Cheers!

Mike

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When 

19 hours ago, unreasonable said:

 

I believe not - expensively sourced research etc, I seem to recall being the reasons.

 

3 hours ago, SAS_Storebror said:

 

Exactly.

Precisely.

Thank you so much for putting the whole truth about these endless debates in just two sentences.

I'm subscribing each and every word of it.

 

When the source is not made public (at least to my knowledge it isn't, correct me if I'm wrong), I see the situation the same as "supplement missing data with assumption". I'm not asking for posting the document, as the devs might not have the rights to do so, but at least name the source, so those interested can get the data too.

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7 hours ago, bzc3lk said:

 

I was quiet surprised how slow the roll acceleration and response was after looking at this footage. :o:

 

 

He does not have someone shooting at him.

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14 hours ago, Panthera said:

 

Well this is an odd one, but perhaps I misremembered. That said our example had a 60% aileron span.

 

Is it possible you could link the report?

According to NACA, it's 43%, checking against Fw factory figures, I ended up at the same.

 

Check the last two links given in the below post:

 

https://forum.il2sturmovik.com/topic/22155-naca-data-indicates-that-the-bos-yak-clmax-is-too-high/?page=2&amp;tab=comments#comment-377312

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Posted (edited)
14 minutes ago, JtD said:

According to NACA, it's 43%, checking against Fw factory figures, I ended up at the same.

 

Check the last two links given in the below post:

 

https://forum.il2sturmovik.com/topic/22155-naca-data-indicates-that-the-bos-yak-clmax-is-too-high/?page=2&amp;tab=comments#comment-377312

 

You misunderstood me, I was talking about an aircraft I last studied aileron effectiveness on, an aerobatics plane :)

 

Thanks for the link! 👍

 

Edited by Panthera

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Hi all,

 

I kinda clean up this mess (did the best I can with my limited time) and reopened it.

 

Lets get a thing clear here:

 

- Devs are in no obligation whatsoever of showing the data they used to build the planes, in the cases they have done so its their free will to do so, again no obligation at all.

- If someone have data, hard one, do a report and send it to the devs. That may change something, posting it here wont since the team wont spend their time digging in the forums. Noted that I say it may change something, it may cus if the engineers of the team do not agree with your data it wont be changed.  Thats the way the 190 was changed, due to a report sent to the devs, not cus all the forum posting.

On 5/28/2018 at 5:58 PM, unreasonable said:

And that is ignoring the mouth-breathers who feel the need to send abusive PMs.

 

If you, or any other member, receive such PMs..please report them. It can be done, if not you can PM me or even add me to it. That kind of behaviour is not welcome is this forums.

 

With that said, if you want to keep talking about the roll rate of the planes, keep it civil.

 

Haash

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3 hours ago, SYN_Haashashin said:

I kinda clean up this mess (did the best I can with my limited time) and reopened it.

Thank you for unlocking the topic.

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Thanks for unlocking this thread again Haash.  While it may not get the devs to change their mind directly it is still possible some good info comes up.

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6 hours ago, SYN_Haashashin said:

Hi all,

 

I kinda clean up this mess (did the best I can with my limited time) and reopened it.

 

 

 

Thanks for your efforts Haash.

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