Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Naudet on March 27, 2002, 09:12:58 AM
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...so there can be no doubt, that this must be fixed.
The text below is a passage from Kurt Tank-Focke Wulf’s Designer and Test Pilot, Wolfgang Wagner, ISBN 0-7643-0644-8
Tank does a brief flight test with a FW190D9 in this book, and this passage refers to the dive speed reached with the D9.
As you can see in the text, K. Tank mentions a dive speed off 700km/h IAS @6000 meter
that translates into
435mph IAS @ 19,672 ft.
also tanks mentions that there is no flutter, no vibration or any shacking of the plane.
I did two test dives, both from 28,000 feet, too copy K. Tanks test.
i timed the dive a bit wrong, so that i could only reach 400mph IAS @ 19k
but even at this speed, the D9 shook violantly.
I still was 35 mph away from Tanks speed, and you got the feeling the AH D9 rips apart in a few sec.
I did a second test this time reaching 400 mph IAS at 20K 8as you can see the timing is a bit hard), and again the bird shook wild.
So this time, i brought anything, a source and a test and so we have the prove that the D9 compresses to early. About 35-40 mph to early, and as the source says the D9 would reach 435mph IAS@19,672 feet without shaking.
This time HTC must fix this, it is proven.
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A note, 190A8 speedometter had a top at 900 kmh, and not in "alarming" red colour.
7gs pulling out a dive at 900 km/h give a clear idea of how good control had this plane at hi speeds. Here, in AH, D9 is a stone at hi speeds and IMO, this is something that needs to be fixed ASAP.
Naudet, some of us tested several planes elev control at hi speed, the looser: G10, the second looser D9 and the uncontested winner the Typh (no compression at all diving from A1 to sea level in DA) seconded by the SpitIX.
Congrats for your findings Naudet, hope they wont be ignored.
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I have that book.:D
It'd be real nice to have the D-9 maintain its manuverability like the P-51 does.
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IAS is just a pressure differential. Because of the shockwave that forms at very high speeds IAS isn't accurate. It's also inaccurate in slow nose high flight because of the angle of the pitot tube to the airflow. I believe Hitech posted before that in AH IAS is accurate at all speeds and attitudes.
--)-FLS----
Musketeers
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Good stuff Naudet.
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FLS, now you will tell me K. Tank the designer of the FW190 didnt know that, at best he was one of the most genius aircraft designers of the 20th century and didnt know about IAS problems.
It is impressive how long some people try to discuss away facts.
If some allied silverbird jockey would bring up, that his test revealed his P-1234 is just a 6 mph IAS to slow at divespeed, the next patch would solve the problem.
But when i spent time testing, working through different sources, asking people that have even more sources, than someone jumps in and blaimes the results to inaccurated indicators.
LMAO
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Naudet if your mind is made up I shouldn't bother you with facts. :D
You might speculate on why there is no buffeting if the IAS is accurate.
--)-FLS----
Musketeers
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So far Naudet has posted pretty good scan and tests and FLS has posted.. uhm what ?
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You might speculate on why there is no buffeting if the IAS is accurate.
FLS, so the point you are bringin in here is, cause there was no buffeting in Tanks dive with the D9 his IAS indicator were not accurate.
The impressive thing is that he flew a FW190A7 too in a test, he dove and reached the same speed.
Guess, both times the indicator was wrong.
As i understand you, you think HTC models the FW190 correct, and the statements of the FW190 designer are wrong?
If that is so, i doubt any damned number an allied plane managed in flight, cause as you stated, indicators are not accurate and so their numbers are wrong too.
Why HTC than still needs data?
If all tests are done with inaccurate indicators, all data is wrong. Point.
And to stop any further discussion of that point.
I did anything HT once mentioned.
I brought a source.
I made a test.
I made a comparison between test results and AH.
I found a difference.
I posted it.
And i trust my test and my sources.
For me the D9 in AH compresses to early. I have proven it.
It should be fixed.
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hmmm , long time a go , in Warbirds ,:) i remeber the Lw planes was maybe not easy to fly but definitely the have lot advantages aven above spitfires , beleve HTC < pyro , HT whatever > dont have nothing negative vs Lw planes but in WB many people givet wery strong moral fedack on Lw planes , if remember corectly LWhiner born in AH , and why in AH now alied planes so dominating ? , in the beginin it was not like this !
i suspect all the problem come mostly from crying out new ocean be the < alied wenies > ,sory but many of you react like ,,AW ,, ;) so must call you like this
sugestion to al dear Lw fans , lets build some serious moral fedback , the real gilty are always hiden somewhere alse , maybe is it not realy HTC who make us unhapy :)
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What Minus?
LW planes sucked donkey nuts in WB. They turned like stuffed pigs, burned E terribly quickly and couldn't do much more than die.
The D-9 in WB was not competetive at all, it could do two things. Hit and Run.
I dunno which WB you played, but the AH LW planes are leaps and bounds beyond what WB had when I played it.
And on top of all that, LW planes are highly competitive in AH. They aren't some super planes like many people(usually LW people) believe, the 109 was built for dogfighting/escorting. The 190 was built to be all around. Good at everything, excellent at nothing.
-SW
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hehe i played the old WB from 1.9 to 2,7 or something , stil have them on cd somewhere all
flyed mostly 190a8 and was skared only niki HO s , actualy flyed FW becose no typhie was in WB , at this time i was in Raf 303 ,and mostly hury 1 dweb but somehow faled in love with 190:D
nothing scare me , only got upset in Lw planes ;)
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Ah, I flew from CK .94 until WB2.0 (gave up after 2.0)... Man, if you guys flew the 190s and 109s of those days, you'd be convinced the 109s and 190s of AH are uber.
-SW
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That picture Naudet added also states that it came all the way up in 700 km/h indicated, 955 km/h True acording to the note. That's is nearly 600 mph (593) true air speed, at that speed, AH D9 has compressed long ago.
Acording to this I am starting to think even the A modells in AH compress to easy.
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Naudet
I made no statements regarding the accuracy of the FW190 in AH. I merely pointed out that IAS gauges are not really as accurate under all conditions as they are in AH. For that reason you can't compare the figures directly. What you posted so far gives the airspeed indicator reading without correction. You haven't proven anything by posting uncorrected IAS figures.
I have no bias for or against any aircraft in AH. I would like to see them all modeled as accurately as possible given the limitations of PC's.
Btw I flew your test and hit 450 IAS level at 19000 ft. At 435 IAS there was moderate buffeting. At 400 IAS there was no buffeting.
Wilbus
The 700kph figure is uncorrected IAS so the equivilent TAS would also be inaccurate. At 19500 ft the IAS at 435 IAS could easily be 35 mph higher than the true IAS. Since the AH IAS is true IAS the 400mph IAS with no buffeting that resulted in my test could be correctly modeling the test that Naudet posted.
--)-FLS----
Musketeers
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FLS you did the test and reached 450 mph IAS with moderate buffeting?
Thats interesting, cause in both dives i made the plane nearly tore apart at 400mph IAS @20k.
Will have to do some more testing on that.
What was you fuel loadout? It should not have influence, but who knows.
Edit: I have redone the test, again, heavy shaking when getting over 400 mph IAS @20k. I level out, at 19K and plane calmed dowe when speed falls under 400 IAS.
I also filmed it, but to my surpise, the film doesnt show any buffeting or shaking.
How can that be, those films not a 1 to 1 copy of the flight?
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Shaking and such, blackouts etc don't show up on film naudet.
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I did the same just now Naudet at of near 400 ias (just under 20k) I was shakin violently appear to be close to ripping apart.....
Good work Naudet..........
doh my film dont show it either :(
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Well we have proof about it even karnak supports it what now?
should they fix this little thing and give the hunstang some teeth or will it be left as is.....<190F8>
nuff said
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edit
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I have seen documentation which states mach 0,76 as critical mach number of the Fw 190. There should be not much difference between the A and D (same wing).
gripen
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Indicated speed is not corrected for compressibility. You can take a good 15 knots off of that figure to get the 'real' speed. Pyro has said that the airspeed indicator in AH reads CAS (calibrated for installation errors). It might even be EAS (corrected for compressibility).
http://142.26.194.131/aerodynamics1/Basics/Compressibility_Chart.html
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0.76 Mach at 20,000 feet is about 395 mph IAS.
Which means that Naudet's flight test finding is consistent with the published critical mach number obtained by Gripen. And the points brought up by FLS and Wells explain the discrepancy from Wagner's account of Tank's test flight. I don't see how Hitech can view this as anything but a non-issue.
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Gripen, do you have references to that documentation stating 0.76 as critical mach?
btw, any info about typh critical mach?
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Mandoble,
That claim is from a collection of German notes on Flight characteristics of Fw 190 and Bf 109, available from the PRO as DSIR 23/14226. Data sheet of the Fw 190 gives following IAS limits:
9000m 500km/h
7000 600
5000 700
3000 800
2000 850
Critical mach number of the Typhoon should be around mach 0,64.
gripen
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gripen, i got the info critical mach number for the FW190 was 0.8, can you give the source were you got the 0.76 from?
and the numbers you posted from the PRO report, those limits were marked on the airspeed indicator of a ditched FW190D9 from 2nd Jan 1945.
There was no test done as far as i know from the RAE on FW190 divespeeds.
So it seems Tanks dive is too me the only know test yet.
And about the correction, if you can take a 15 knots of (around 18mph right?) the AH D9 still compresses about 15 mph to early.
As i said the difference i found was 35-40 mph, substrat 20 from it and you still have a differnece left of 15-20.
But i try to to a test on gripens numbers. As far as i can remember the AH would is be capable of 850km/h (528mph) @2km (6557 feet).
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Naudet,
The source is mentioned above, just go to:
http://catalogue.pro.gov.uk/
And you can find it using reference number mentioned above. And it is not a RAE report but a collection of German notes. Also mentioned dive IAS limits are not from RAE but from original datasheet of the D9 so these should same as in the indicator.
gripen
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Hi Gripen,
working with the compression correction chart Wells linked, the Fw 190D-9 placard works out to the following Mach numbers:
9000m 500km/h Mach 0.71
7000 600 0.74
5000 700 0.76
3000 800 0.77
2000 850 0.77
Of course, placard values tend to be conservative and are not only selected for the Mach number, but also for the desired engine revolutions. The Fw 190D-9 numbers look quite ambitious, though, so I speculate the impact of the latter wasn't decisive.
>Critical mach number of the Typhoon should be around mach 0,64.
That's interesting, we recently discussed it but had no numbers. I guess the Mach number is from PRO records as well?
Regards,
Henning (HoHun)
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Note that the compression correction chart is for CAS not IAS. The
IAS position error is greatest at minimum and maximum airspeeds. You have to correct Naudet's posted IAS speeds to CAS before adding the compression correction.
--)-FLS----
Musketeers
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HoHun,
Mach number 0,64 for the Typhoon is from "RAF fighters part2" by Green and Swanborough (same number is also mentioned in couple articles from the 40s like Aeroplane, March 1945). It is not real tactical limit but just a speed where the wing entered the compressebility region, tactical limit should be somewhat higher. In the case of the Tempest similar number was mach 0,73 but the tactical limit was mach 0,8.
gripen
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Here the results on the numbers from the document gripen mentioned:
i tried to hit the following speeds:
435mph IAS @ 16,393 ft
497mph IAS @ 9,836 ft
528mph IAS @ 6557 ft
the test was flown with a FW190D9, full fuel, full ammo, fuel burnrate set to 0
the procedure was the following, climb to 25k, than dive to the 1st altittude and level there out, looking when the plane stops shaking.
Again while in the test, i noticed i would not be capable of going far over the given speeds, but that was not necessary at all
results:
415-420 mph IAS at 16k, plane stops shaking
475 mph IAS @ 9,5k, plane stops shaking
500-505 mph IAS at 6k, plane stops shaking
all results show that the speed in AH is off bye about 15-30 mph.
A digital speedometer would help alot, but due to the fact that at 9,5k and 6k the needle stop at a marking it was quite easy to estiminate speed, more problem at 16k but needle always stayed under the 425mph marker.
And as HoHun mentioned, german safety speeds/data are quite conservative, planes, U-Boots and other types of vehicles could usually exceed those limits without taking harm.
P.S. i did a brief test on FW190A8 dive speed a few weeks ago, and that plane roughly matches above numbers. So it is really just an D9 related issue here. Why should we have one FW190 dive slower, when i fact it was the best diver of all 190s.
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The placarded never exceed speeds are not the onset of buffeting speeds.
Nothing in this thread proves that the D9 is too slow or compresses too easily.
--)-FLS----
Musketeers
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Very simple question here: In AH why does the D9 compress before the A8 and have worse control authority at high speed? That is my question. They use the same wing.
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Hi FLS,
>What you posted so far gives the airspeed indicator reading without correction. You haven't proven anything by posting uncorrected IAS figures.
To be more accurate, the numbers Naudet posted are of unresolved status.
Since there are indications Kurt Tank conducted a controlled test in a specially instrumented aircraft (note the mention of a G meter that wasn't usually fitted to production aircraft), I'm confident that the test results were carefully corrected for all relevant factors.
In fact, the account looks to me like the author took the description of the test procedure and tried to turn it into something more gripping. The procedure he discribes is actually very similar to that used by Messerschmitt (according to Radinger/Otto/Schick's "Me 109" books). Even the altitude at which the top speed was achieved is close for both types: The Me 109 achieved 906 km/h TAS at 5800 m, so a 955 km/h TAS at 6000 m for the Fw 190D-9 seems not unlikely.
Regards,
Henning (HoHun)
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Hi FLS,
>You have to correct Naudet's posted IAS speeds to CAS before adding the compression correction.
If someone could provide the D-9-specific correction factors, I'd run the numbers again. I'd guess the error is in the region of 2%, and since the placarded numbers are usually conservative, I don't think the numbers I posted are too unrealistic as they are now.
Regards,
Henning (HoHun)
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Hi Gripen,
>It is not real tactical limit but just a speed where the wing entered the compressebility region, tactical limit should be somewhat higher.
Thanks for the details! Mach 0.64 seemed very low indeed.
>In the case of the Tempest similar number was mach 0,73 but the tactical limit was mach 0,8.
The P-51 manual mentions 0.75 for that purpose, and this seems to have been the placarded number as well. Like the Tempest, it could actually go still faster. I'd say it would be reasonable to assume the same applied to the Fw 190D-9 as well.
Regards,
Henning (HoHun)
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HoHun
Don't IAS position errors have to be determined empirically?
I wasn't doubting your figures, I was just pointing out that the chart used CAS not IAS.
I'm not saying it's impossible for Kurt Tank to have calculated the actual TAS, I just don't see that in the material Naudet posted. I also don't see anything to indicate that Tank thought the IAS figures were accurate at that speed. Don't you think it's significant that there was no buffeting?
I haven't taken the position that the AH D9 model is correct. I'm just saying that I don't believe the information Naudet provided has shown that it's incorrect.
--)-FLS----
Musketeers
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The absolute figures are not too worrisome, the (apparent) fact that the D9 compresses before A8 is.
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Also it is impressive that critical mach for D9 is 0.76 for the tiffie 0.64.
As tactical limit seems to be usually higher, the D9 should be capable of higher mach as the tiffie, or atleast the same.
But in AH you have a totaly different picture.
D9 compresses, shakes and losses elevator authority.
But yet, i never managed to compress a tiffie, nor did i manage that its elevator got somewhat heavier.
And as Raubvogel and SageFIN mentioned, there is still the point, why the D9 compresses earlier than the A8. The D9 was known for its better dive, but in AH the situation is inverted.
Why is this so?
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Originally posted by Naudet
Why is this so?
Only Pyro and perhaps HiTech knows ...