Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: MANDOBLE on April 05, 2002, 03:55:44 AM
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Why a so noticeable degradation of control above 300 mph between 190D and 190A? Doras outmaneouvering 190As at hi/med speeds is just a myth?
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Mandoble, I don't have an answer myself, but on a different BBS recently, Wilbus asked the same thing and Wells provided an answer. Here it is for what its worth to you.
Wilbus wrote: Hey all, lately there have been a discussion over in the AH forums about why the Dora compresses easiler then 190 A5 and A8 version, it's basicly the same plane with a longer nose and tail and a different engine, it uses the exact same wing.
So can anyone explain to me why it has worse high speed handeling then the earlier A variants, seems very odd, specially since the Dora was designed for high speed and accelerates/dives better, did it have worse high speed handeling in R/L?
Wells wrote: I don't have a direct reference for the 190D, but the Ta-152 was found to have a higher stick force per g, than the BMW powered 190s, according to Eric Brown. It would be reasonable to assume the same for the 190D with it's tail surfaces moved farther aft.
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This may be reasonable for the Ta152 at hi speeds due its much larger surfaces, but that is not the case of 190D9. The effect here is the opposite, Ta and A series have both good control at hi speeds, D9 is a brick. You get few degrees quickly, pure AOA gain and then it becomes a pure brick depending absolutelly on the trims (very slow reactions).
Also, at any speed it is very susceptible to trim changes, specially to elevator trim. In RL there were only a small trim control for the elevator (+5/-5 dgrees), and no more than that. It seems that this plane rarely needed trimming adjustment. Here the D9 is very trim dependant.
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Vermillion, the stick forces per G that wer increased were the roll input forces.
They increased due to the greater wingspan.
And as i mentioned in previous posts, Kurt Tank test flew both a FW190A7 and a FW190D9.
They had the same diving characteristics. Stable, good handle no shaking.
Tank mentioned that the D9 did a bit better in speed accel etc. due to the new engine.
This time i won't post sources, cause last time it didnt even help.
Fact is:
in AH FW190D compresses earlier than FW190A, but all the data i have from about real D9 and A-Series, say the D9 was better in dive (most must have been better acceleration, cause critical mach was the same on both, cause the used the same wing)
So in AH the D9 and A-Series FW should compress the same.
And about elevator authority, the tailplane of the FW190 is longer, which actually gives it a longer handle when pulling out the elevator. The D9 should from this point have lighter elevators than the A at speed, cause with the same elevator deflection, you get a greater force moving the plane up or down, cause the handle is somewhat longer.
Or do those physical laws dont apply to aircraft?
@Mandolbe: i wonder that you still try to post those things, i totaly have stopped all comments on such things cause the only reaction i get is ...none.
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Hitech did respond to it in another thread but the response was not very useful. The *impression* I got from Hitech's response was that he had seen Kurt Tank's report sometime in the past but did not feel it was reliable. Hitech did not say why he felt this way nor did he provide a counter source.
I'll try to locate that post and reference it here.
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Naudet, I see no other way to have a minimal hope of HiTech revising the "brick".
Mudd, good luck in your search, didnt remember any comment of HT about this matter.
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It's very simple. You post your thoughts/data here. HiTech reads the boards. If he feels that you have a valid point, I'm sure that he'll make a change to the model, or at least look into it further. If your data trumps his data, BINGO flight model change. As customers, we can expect a degree of progress with the game. I believe that we get that. What we can't expect (in my opinion of course) if for HiTech to come in here and explain to everyone everything related to anything that anyone wants to complain about. I believe his quote was "Could it be that we just dissagree and get tired of posting the same things..." I've said it before, we don't know what information they model on. We don't know if there is one standard source, or multible sources depending on nationality of the plane, or if the planes are modeled after a combination of many sources (an average of certain avaliable sources for example). Anyway, I don't think that you can consider it being "ignored" just because HiTech doesn't respond in here. I think that he just doesn't want to get into a fight with his customers every week.
Just my observation,
-Sikboy
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Ok, found it in the "Torque Effect" discussion.
Hitech 3/29: "So far when people think they have found problems with it, it's has been do to unclear specs they are reading. When you dig deaper you find what the varence is in the test data. See the 190 f8 thread. We have seen report data that has been requoted down threw the years that is so obviously wrong,but none technical types just take it for granted. (the 205 comes to mind)"
My assumption was/is that hitech is refering to the D9 vs F8 compression and the Kurt Tank flight report.
Or he could be talking about something else altogether...
(BTW, what is the 205 issue he is talking about?)
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Originally posted by Naudet
And about elevator authority, the tailplane of the FW190 is longer, which actually gives it a longer handle when pulling out the elevator. The D9 should from this point have lighter elevators than the A at speed, cause with the same elevator deflection, you get a greater force moving the plane up or down, cause the handle is somewhat longer.
Or do those physical laws dont apply to aircraft?
That's what I've been trying to say Naudet. Lengthened tail should make for a longer "lever", which should keep elevator authority the same or possibly better, despite the change in CG from installing the Jumo.
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well we are waiting, evidence has been presented from what seems to be a unquestionable source. tests have been done showing results that are indicating the flight model is wrong. hts responce dosent seem to have anything to do with this situation . how can you missunderstand
" PLANE NO SHAKE OR FREEZE UP LIKE ROCK AT 400 ias at 19 k"
Kurt Tank= guy who knows more about aircraft design that any two that have ever read this bbs including ht
the plane is way off, its not a technical missunderstanding just fix it ?
or mayby Kurt Tank and Kelly Johnson were just lieing :)
(refeference to still screwed up compression on 38 )
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Just a question then... Why wouldn't HTC fix it if they know it's wrong?
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What exactly are the FW190 compression speed differences in AH? I've compared the FW A and D and don't see the big disparity that Mandoble claims.
--)-FLS----
Musketeers
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if you take both up hi and run them into compression the onset of compression and loss of controll happens much more slowly in the a8 as speed increases. its not a small difference if you are in a d9 and you feel buffeting you got about 2 sec of little control and then a brick ( all this at speeds kurt tank himself found the plane to be vibration free and quite controlable ) , silence from htc so far.
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FLS, vader described that perfectly.
Compression speed of the Typh is lower but it also keep full control where D9 is just a brick.
We are not talking about the compression itself, but the control at a range of speeds between 300 mph and the total loose of control (even with trim).
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HFMudd wrote:
(BTW, what is the 205 issue he is talking about?)
Perhaps HT is talking about the 202 and the issue is about Breda SaFAT MG rate of fire.
I have to say that in this case HT not just answered to my questions and considered the data I posted but also modified in version 1.09 the wrong data about bredas mg rof.
So we have the evidence that ht reads forums and consider the issues proposed by the customers.
As a customer and a 202 fan I thank him.
More peas per sec now! :D
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It's been pointed out in another thread that AH IAS can't be directly compared to historical IAS data. I think it would help this discussion if the speeds at which the various FW-190's compressed or lost pitch authority was posted rather than just a general statement that it happens. I haven't noticed a big discrepancy so maybe some numbers would help me see what I've missed.
If anybody has any information on the effect of the longer nose and fuselage of the D9 on it's drag and compression speeds compared to the A8 please post it.
When I tested the tiffi it lost it's wings when the FW190's kept theirs so I don't see where the relative modeling is incorrect. With the limits on the speedometer it's also difficult to compare the compression speeds.
--)-FLS----
Musketeers
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FLS, you are one, we were first five and the last time three. D9 augering and Typh recovering without using trims. If any doubt, look for my at MA and we may redo the tests in DA.
And I repeat once more, this is not about when these planes get compressed, but about the loose of control well below comopression speed. If you want a mock combat using D9 vs Typh at hi speed look for me also in MA, D9 has just 0 chances to keep alive except if it try to extend by speed (not maneuvering) for almost an entire quadrant. Combat up to 20k.
Of course more numbers will help, but critical machs of both planes have brrn already posted several times, having D9 almost 100 mph of advantage before total compression.
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FLS, the speed for all FW190 were those. i gave in the "D9 compresses to early thread".
And about the compression difference in AH. Its about 25-30 mph IAS.
The FW190A dives like i would expect it to dive (numbers given in that other thread), but D9 compresses earlier. But it should not.
And about Hitech comments. It would in many cases just help when Hitech comes in and gives a comment, which sources might be wrong (and those he refers to are in a F8 thread not with D9 dive performance). A short explanation would help everyone.
But the way it is now, we dont even know if our thoughts reach HT, we don't know if he looks in the new sources.
They always say, give us numbers, sources and tests. I have given such things, but i didnt get a response - negative or positive. And cause of that i am tired of posting such things. Why should i spent time testing something, reading endlessly through my books, searching for original factory data when the result is nothing?
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Originally posted by Naudet
A short explanation would help everyone.
No it wouldn't. Just look at the torque thread. HTC came out and said "I have no doubt of my numbers" but that wasn't enough. They were still questioned. All a short explanation does in these threads is open up a larger argument. It also opens the door for future arguments, and claims of dissproportionate response from various people chasing after various improvements.
-Sikboy
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I haven't found any high speed control issues with the D9. I really don't understand what the problem is.
--)-FLS----
Musketeers
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FLS compare it to the A8.
I dunno how, but you couldnt even copy the dive test results all others got in the "d9 compresses to early" thread. Maybe you have a different D9, who knows. But for people that often switch between fw190A and D the problem is obvious.
I am a pure D9 driver, but after Mandoble mentioned the difference, i did some test, and without difficulties the differences could be recognized.
@sikboy: That is not what i call a short explanation. It was just the statement of Hitech that he doesnt doubt his numbers. And in the explanation he didnt mention if his numbers contain all torque effects. He just explained that you get pure engine torque by hp/rpm or anything like that. He didnt even described all elements that influence torque in AH.
I am still waiting for an explanation why D9 should have worse dive characteristics than the A-Series. All sources i have state the same or better dive characteristics for the D9, i now want to know why thats the exact opposite in AH. There must be a reason. If not, its a fault and should be fixed.
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Delivery of the Fw 190D-9 began in August 1944. The first Gruppe to convert to the "Dora-9" was III/JG 54. Their initial assignment was to fly "top cover" for Me 262 jet fighters during takeoff when the jet fighters were specially vulnerable because of their poor acceleration. At first, Luftwaffe pilots were somewhat suspicious of their new fighter, since the Jumo 213 was thought to be only a "bomber" engine. However, it soon became apparent that they had a winner on their hands. The "Dora" could out-climb and out-dive its BMW 801-powered predecessor with ease, and it possessed an excellent turning rate at speed. An experienced pilot could pull a tighter turn in a D-9 than he could with the BMW-powered FW-190A. The general opinion of the pilots who flew the FW 190D-9 was that it was the finest propeller-driven fighter available to the Luftwaffe during the entire war. In fact, many of its pilots considered it more than a match for the redoubtable P-51D Mustang.:p :p :p
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Naudet
I compared the A8 and D9 and I don't see the problem. As you pointed out, we get different results testing the same conditions. Maybe you could post specific performance differences that are obvious to you instead of general statements about your opinions so I'll know what to look for.
--)-FLS----
Musketeers
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Originally posted by Naudet
That is not what i call a short explanation. It was just the statement of Hitech that he doesnt doubt his numbers. And in the explanation he didnt mention if his numbers contain all torque effects. He just explained that you get pure engine torque by hp/rpm or anything like that. He didnt even described all elements that influence torque in AH.
So it wasn't satisfactory. And I don't think it ever would be satisfactory. that's my whole point.
-Sikboy
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FLS i posted the numbers back in another thread, but here what i found out in a comparative dive test with an FW190A8 and a D9.
D9 starts to shake @475mph IAS @ 9.5K
A8 starts to shake @495-500 mph IAS @9.5k
that a difference of 20-25mph as you can see.
And as i said, i filmed those things, but what i didnt knew was, that you cant see compression in films.
Both planes were at 100% fuel.
Edit: Just to be sure i repeated the dive test with an A8, but this time the bird started to shake at 475 mph IAS @9.5k. So there is no difference in compression! The only question i now have why both tests (the other one ist about 4 weeks ago, still with 1.08) gave different results. The films don't help much here cause they dont show any compression at all.
So far i can only conclude i made a mistake in the 1st test. Dunno how as i never changed the procedure, but somewhere there must have been a fault.
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Back to the topic. No matter whether both planes compressed at 457mph or not. My question was about handling at med/hi speeds not about the speed where both planes get compressed.
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off topic a little
once in th ma i asked ht why the nikis torque was screwed , he responded in what way ?. i said at edge of a stall you can instantly firwall with wep ( full power) with almost no change to the ac as far as torque effects. he said that was correct
i ask you is it ? methinks ht hates to be wrong.
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Is Lord Dolt Vader the next biggest LW jerk?
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ahh nice insult . you also believe the niki torque effects or lack there of are correct?
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bump for chime in thread
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once in th ma i asked ht why the nikis torque was screwed , he responded in what way ?. i said at edge of a stall you can instantly firwall with wep ( full power) with almost no change to the ac as far as torque effects. he said that was correct
i ask you is it ? methinks ht hates to be wrong.
lord dolf vader
Maybe, maybe not. Consider the Bearcat. One would expect that plane, with its high power to weigt ratio, big 15' prop and compact design to be quite a handful. Yet, because of the way it was engineered it was a very docile plane from a torque/p-factor standpoint according to pilot reports. Takeoff, for example, required practically no trim or rudder input:
Runup complete, the final checklist is run. Unlike many fighters, no trim is preset, or needed. Grumman learned many lessons from the earlier aircraft, and got a wonderful harmony of engine offset and surface deflection, so that very little yaw is evident on the takeoff roll. Not allowing the tail up helps, there is no gyroscopic effect.
This in a CAF takeoff protocol that requires full power takeoffs. Doesn't make "sense" to me, but that's the way it is. Perhaps the George is similar in this regard.
Charon
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Just to chime in without having read all the posts. Madno, the TA152 is MUCH worse then the D9 at high speeds, compress alot easier and has got both worse roll and elevator controll then the Dora. And Dora does it worse then the A versions.
Don't know if it was this for real (as documents from WW2 seem to say it was the opposit) but if Whels is right the longer fuselage would be the reason to worse elevator controll.
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It is extrange, I found Ta controls at hi speed light, the major cause of all my wingless Tas. But in my comparison I forgot to include the Ta, I'll try to find some time and test that plane too.
I may be wrong, but the longer fuselage may be an advantage for elevator control and not the contrary. Your plane is just pivoting nose up around its GC but you have a longer "arm" (the longer tail) applying the same force. D9 fuselage is more aerodinamic than A series, the extra length may be compensated by this fact resulting in a similar drag.