Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: Souless on June 17, 2007, 10:01:53 AM
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I was browsing the forums and read where widewing stated it was very similar to the P-38 critical mach.
Having flown the P-38 for a number of years here I am well aware of the compessibility factor involved.
Now I rarely fly the typhoon however it was quite easy to hit 500 without buffeting.
If the flight model is utterly wrong in the typhoon then it should be fixed.
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As it happened I just re-read Roland Beaumont's book 'Fighter Test Pilot'.
I quote ' at the advertised dive limit of 500mph there was adequate control remaining, though with heavy control forces and a most impressive noise level. (My italics).
He also says it was very manoeuvrable at speeds above 400mph which was exceptional for that period.
I would not be inclined to disagree with such an esteemed authority as Roly Beaumont. So it would appear that the flight model of the typhoon is in fact accurately modelled. Maybe it should be perked.;) I have been flying the Tiffie lately and am beginning to like it.
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Hmm would like to hear more on this
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Mach number is not directly tied to indicated airspeed.
So quotes of 500 mph without data on altitude is basically irrelevant.
The P38 critical Mach number is right around .67 if I remember correctly.
NACA published a chart showing mach number vs altitude
Look at it here.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093483_1993093483.pdf
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Typhoons had an extremely thick airfoil section. In testing a Typhoon was dived to 500 IAS at 10,000 feet and was virtually uncontrollable, with a tendency to tuck under.
Its critical Mach should be in the area of 0.69, very similar to the P-38s. As it is the AH2 Typhoon does not begin to buffet until 545 TAS at 20,000 feet, which translates into Mach 0.77, which is almost identical to the Tempest.
My regards,
Widewing
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what would that be in true air speed widewing?
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Golly, if that kind of change ever happened that's gonna piss a lot of chickenshi* BoreNZoomer Tiffy addicts.
Such a lovely thing to imagine.. mmmm
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Golly, if that kind of change ever happened that's gonna piss a lot of chickenshi* BoreNZoomer Tiffy addicts.
Right on the money man:aok :aok
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We need to get the detatchable tail section too.
:)
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Originally posted by jon
what would that be in true air speed widewing?
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093483_1993093483.pdf
Chart is on page nine
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Its been covered in several threads, from Duma:
'The speeds given in the Typhoon's table (of 'limiting indicated airspeeds against height bands') were, after allowing for position error, equivalent to a Mach number of 0.79, which was higher than for any contemporary piston-engined fighter except the Spitfire IX. Our job at RAE Farnborough was to determine how critical this limiting Mach number was if taken to the ultimate loss of control. These tests were normally started at the highest possible altitude, so that if loss of control did occur in the dive the Mach number would automatically reduce as height was lost, provided the dive angle was kept constant, and thus allow control to be regained.
The aircraft to be used for the compressibility dive tests was Typhoon IB EK154, fitted with a Machmeter and powered by a 2,200hp Sabre IIA. THe aircraft was climbed to 32,000 ft and after a 3 min level run at full throttle at that height was half rolled and the nose allowed to drop 30 degrees before half rolling again to maintain that dive angle. The indicated Mach number (IMN) had built up to 0.82 by 27,000ft, with moderate buffeting, then at 0.83 a noticeable nose-down change of trim occurred and at the same time the buffeting inceased. Finally at IMN=0.84, the nose-down trim change increased dramatically and even a two-handed pull on the stick could not effect recovery. I could just manage to keep the dive from steepening, and held on with considerable effort until, at 20,000ft, the nose began slowly to rise; by 18,000ft recovery was complete. From these tests it was clear that the true limiting Mach number of the Typhoon was 0.79 and the true critical Mach number was 0.81.'
...in any case if somebody has any hard data they can send it to HTC.
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The Typhoon's airfoil was the NACA 2219 at the root and NACA 2213 at the tip... These airfoil designs worked well up until about 500 mph, where the onset of buffeting was sudden and quite pronounced. This is an 18% wing (at the root), at least 5 inches thicker than the wing of the Tempest, which was designed to raise the aircraft's critical Mach, which it did.
I recall that both of these fat airfoils had a critical Mach of 0.69 to 0.70, which is well below the ridiculous 0.81 Mach quoted above..... Those guys had some serious instrument error. 0.81 is far higher than the P-51, P-47, Fw 190, Bf 109, F4U ad nauseum.
The only other aircraft I can find that utilized the 2219 airfoil was the Airspeed Courier (with NACA 2212 at the tip). This was a single-engine transport dating to 1933.
My regards,
Widewing
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What airfoil did the Tempest use? If the Typh's is that much thicker and has more camber, then the critical mach should be much higher right?
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.69 mach for the typhoon would love to see this modelled properly then
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From Typhoon pilot's notes:
(http://img.photobucket.com/albums/v424/timppa/TyphSpeed.jpg)
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Originally posted by Stang
We need to get the detatchable tail section too.
:)
Well -
Only the early Tiffys suffered from that problem.
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Read a book detailing how the typhoon was thought to be very controlable in a dive, and could be taken above 500 with no probs, somone has mixed up, or misspoken....
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Originally posted by stephen
Read a book detailing how the typhoon was thought to be very controlable in a dive, and could be taken above 500 with no probs, somone has mixed up, or misspoken....
Stephen,
there are very few people on these boards that I will sit up and take notice when they speak.When widewing speaks I take notice,he is one of the very few that have earned that respect from me.
I'm not taking this as gospel from him but I dont believe he has mixed up or misspoken.
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http://www.virtualpilots.fi/hist/WW2History-Manuals.html
Here is the 109G-2s flight manual which gives a max speed of 750 km/h (466 mph) in a dive. Certainly thats not its critical mach #.
In fact almost every pilot manual I have ever seen states the max diving speed at below its critical mach #, but then they were talking about a safety regime, not what you could push it at its design maximums.
My point is that all the WW2 fighters dove faster than their listed "pilot manual" speeds, and you can only go by more detailed data than that, which is what HTC does.
You can find numerous examples on the BB already of this, as for example, the P-47 debate.
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Originally posted by Squire
[url]
In fact almost every pilot manual I have ever seen states the max diving speed at below its critical mach #, but then they were talking about a safety regime, not what you could push it at its design maximums.
My point is that all the WW2 fighters dove faster than their listed "pilot manual" speeds, and you can only go by more detailed data than that, which is what HTC does.
Sure, you can exceed critical Mach.... But you cannot do that without loss of control. In AH2 the Typhoon doesn't even begin buffeting until Mach 0.77, which is simply too high.
As to manuals... The P-38 manual is specific in its max speed dive limits. It warns you not to assume any margin exists... It does not. Exceed the limits in the manual and you WILL lose control.
My regards,
Widewing
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I think we have established that the Typhoon is fast in a dive. Beaumont's 500 mph dive is confirmed by the pilot's notes 525 IAS which equates to 500 or so RAS. The correct TAS and Mach number is another matter. I would tend to believe Widewing when he says that .81 is high and probably a case of instrument error.
But essentially if you dive at 525mph indicated, as per the pilot's notes you shouldn't expect to buffet or tuck under. The notes after all are written for the perusal of ordinary squadron pilots not test pilots like Beaumont.
AH though, is not real life so it really has to be subject to inaccuracy or programming error. Even the atmosphere we fly in is simply a representation of reality. You simply don't have the variations in temperature or pressure or humidity you get in real life.
I don't think the Tiffie model needs much tinkering. It's as close as any in the planeset.
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The point is that 525 IAS (minus the 25 mph error) at sea level is simply 500 mph TAS and under the critical mach #. 525 IAS at 25K is ludicrous speed TAS (not even achievable by a WWII fighter), and the pilot is along for the ride. P-51's and 47's were placarded for a 500 IAS Vne, but they also had placards warning them against doing that at altitude.
Throwing all other "real life" data aside--if the Typh critical mach is equal to the Tempest critical mach in AH2, the Typh model isn't correct (at least with respect to the Tempest). If indeed it had a thicker and more cambered airfoil than the Tempest, it would have a lower critical mach #. What value it "should" be is another matter entirely.
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The 525 IAS in the manual is undoubtably referring to sea level to 5000 feet or so. The Typhoon rarely operated above 15,000 feet. Nowhere does it say 525 at 25k, and no RAF pilot would ever attempt a speed like that unless they were certifiably insane.
525 at 5000 feet would give you Mach 0.77.
As for the Tempest I have seens its crit mach listed as 0.83, as to wether thats close or not, I dont know.
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Originally posted by cpxxx
I think we have established that the Typhoon is fast in a dive. Beaumont's 500 mph dive is confirmed by the pilot's notes 525 IAS which equates to 500 or so RAS. The correct TAS and Mach number is another matter. I would tend to believe Widewing when he says that .81 is high and probably a case of instrument error.
But essentially if you dive at 525mph indicated, as per the pilot's notes you shouldn't expect to buffet or tuck under. The notes after all are written for the perusal of ordinary squadron pilots not test pilots like Beaumont.
AH though, is not real life so it really has to be subject to inaccuracy or programming error. Even the atmosphere we fly in is simply a representation of reality. You simply don't have the variations in temperature or pressure or humidity you get in real life.
I don't think the Tiffie model needs much tinkering. It's as close as any in the planeset.
I suppose we could debate this back and forth. Indeed, this issue is not just related to the Typhoon. I was able to get an FM-2 up to 600 mph TAS in a dive, which is 117 mph faster than a real FM-2/F4F could attain due to drag. I can dive an A6M2 at speeds more 140 mph faster than where the ailerons shredded and the skin wrinkled, and it doesn't begin to buffet until 550 mph TAS. No zero ever saw 550 TAS with wings attached. Then there's the A6M5, which gets into an uncontrollable death spiral at just over 500 mph TAS. Why are they so different?
I'll argue to the cows come home that the Typhoon should see the onset of buffeting at Mach 0.70. It's NACA 2219 wing doesn't like speeds above that. Which is why the Tempest wing is completely different.
By the way, 525 mph TAS @ 5,000 feet is Mach 0.70.
525 mph IAS @ 5,000 feet, corrected for position error is closer to 498 mph IAS, or 547 mph TAS, which is Mach 0.73. The Tiffie ought to be shaking quite badly at that speed.
My regards,
Widewing
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Hi gang:
This illustration might be helpful: (from the US Centennial of Flight page)
http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Flow/TH19G6.htm
(http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Flow/TH19G6.jpg)
Don't mistake compressibility effects with critical mach number. Critical mach number is the point that supersonic flow occurs on the wing at some point. This doesn't mean that shockwaves have formed and are strong enough to cause significant separation of flow which leads to compressibility effects on control.
For stability and control issues to occur the shockwaves have to reach a point that causes enough premature flow separation behind them that impacts the tail. This flow separation creates the compressibility effects we are aware of e.g. a) buffeting - because the downwash from the wing on the tail subjects the tail to extremely turbulent flow due to the separated flow, b) tuck under - because the downwash from the wing is reduced which increases the angle of attack on the tail, c) loss of pitch authority - because of elastic deformation on the tail boom which reduces the effectiveness of the elevator.
Tango, XO
412th FS Braunco Mustangs
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For comparison, Tempest V dive limits:
(http://img.photobucket.com/albums/v424/timppa/TempSpeed.jpg)
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Again Widewing, the intardnet-historian, is disputing professional test pilots and controlled test dives with mach meters.
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Originally posted by TimRas
For comparison, Tempest V dive limits...
I don't suppose the Typhoon POH has an altitude chart such as this?
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Not only that, AH Typhoon is too fast!
Max speed of Typhoon at WEP at...9 lbs at 3700 rpm
(http://www.wwiiaircraftperformance.org/typhoon/typhoon-level-ft.jpg)
AH Typhoon's speed at WEP (9 lbs at 3700 rpm...)
(http://www.hitechcreations.com/ahhelp/models/charts/typhoonspd.gif)
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The AH Typhoon climb rate rate is somewhat conservative...
(http://www.wwiiaircraftperformance.org/typhoon/typhoon-climb-ft.jpg)
(http://www.hitechcreations.com/ahhelp/models/charts/typhoonclmb.gif)
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Originally posted by Viking
Again Widewing, the intardnet-historian, is disputing professional test pilots and controlled test dives with mach meters.
RAE is over rated.
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Over modeled you mean. ;)
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Originally posted by Viking
Again Widewing, the intardnet-historian, is disputing professional test pilots and controlled test dives with mach meters.
I can when the data flies in the face of physics...
By the way, if you wish to participate in a manly discussion, please change out of your tutu first. Inasmuch as you rarely have anything of substance to contribute, feel free to sod off.....
Widewing
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Oh brother. We're talking about maximum dive speed of a Typhoon, as if the physics of this game were realistic. In case you don't understand, the physics of this game aren't real, and even the much ballyhooed torque effects aren't close to what they would do in real life. It's a game, it's not real, and unless we're going to go test these planes, as originally designed, and using properly installed modern instruments, we really aren't going to know what the actual capabilities are. In the FWIW category, not even the Bell X-1 had a properly working mach meter when it broke the sound barrier the first time.
"Yeager: We didn't—we had no idea anything was going to happen. There was some indication on the previous Friday's flight that we had a very large error in our Mach meter. Otherwise we were indicating about 9.3, or .94 Mach number which was 94 percent of the speed of sound. There's some indication when NACA reduced the data from our instrumentation in the airplane that we're going a lot faster than indicated. And there was some, a little bit of excitement that said, hell, we, it looks like we've, we've been up to about 99 percent of the speed of sound. And we still are in buffeting and the airplane is shaking quite a bit. You know, they weren't sure, because you, you're in an area where very little is known. They had no wind tunnel data, nothing, and everything was trial and error. And there was some indication that we had been going faster than we had thought. But we had no idea what was going to happen on the next flight. And when we got the airplane up to oh, about 96 percent of the speed of sound indicated, that was almost Mach 1. And when we went a little faster the Mach meter went off the scale. And ah, when it did all the buffeting smoothed out, because of the supersonic flow of the whole airplane. And even I knew we had gotten above the speed of sound. And I let it accelerate on out to about 1.06 or 1.07, seven percent above the speed of sound, and the airplane flew quite well. And I got some elevator effectiveness back, but not very much."
( Copied from http://www.pbs.org/wgbh/nova/barrier/men.html )
Observation: The X-1 had proven inaccurate instrumentation, even though it was the most advanced plane of the time.
Conclusion: Published performance data for WWII aircraft, even from the manufacturer, isn't necessarily correct.
If HTC ever makes a perfect physics engine, then great. If they ever do, then by definition, the performance of the aircraft will end up exactly where they should be, as long as the planes physical data is accurate. If that ever happens, there will be others who complain about it not matching published data, so the argument will never end. Until then, it's just a game. A fun game, granted, but still a game.
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I heard there's a new sim game that will use "fluid physics" as oppose to decades old "vector physics":noid
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driven by the new line of quantum computers? ;)
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The P 38 was notorius for it's compressability problems in the dive...in all I have read about the Typhoon,and it had many problems-carbon monoxide ingress in's to cockpit,tails detaching,engine failiure's none of which were fully solved compressaability in the dive never seemed to bother it's pilots most of whom prefered to dive bomb - when carrying bombs-due to the better chances of a hit and less chance of being brought down by AAA.
The pilot handbook says it all,Typhoon pilots had a lot to worry about compessability was not one of them.
:aok
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I pretty much agree with Widewing in his analysis and I'd like to point out the difference between early Hurricane and Spitfire designs having same hp and very different speed characteristics. The same kind of comparison can be used between Tiffie and Tempest too. The Tiffie has the weight and power to make a high speed dive but I guess that the wings are under tremendous stress where their thickness and strength are really needed, but that because of their unsuitability for such flying.
But it is an aerodynamical fact that thickness can be troublesome depending of the location of the thickest point as if it is near the leading edge as in 2300 series and not in the middle as in profile used in e.g. Pony. Wing sweep can help to overcome compressibility effects in thick profiles but there are practical limits too and IMO Tiffie does not have such sweep to have any significant effect.
My guess is that Tiffie feels like diving like a brick meaning the relative lack of responsiveness when compared to planes with better suited profiles for high speed such as in e.g. Spitfire.
The behavior that troubles me is the behavior of such thick profile in high speed when the elevator tries to force it to change its AoA. Does it respond readily or just fall through the air in compression effect without noticeable change in flight path?
-C+
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Wow Widewing......your one smart cookie:aok
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Originally posted by Kweassa
Golly, if that kind of change ever happened that's gonna piss a lot of chickenshi* BoreNZoomer Tiffy addicts.
Such a lovely thing to imagine.. mmmm
It's a more challenging flight than most of the planes flown commonly in AH.
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this just looks like americans trying to say that thier planes were / are best ever and every one elses stink...blah blah blah......we won the war.....blah blah blah......we had ben afflick.....blah blah blah......
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Originally posted by B3YT
this just looks like americans trying to say that thier planes were / are best ever and every one elses stink...blah blah blah......we won the war.....blah blah blah......we had ben afflick.....blah blah blah......
Not at all actually
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Originally posted by B3YT
this just looks like americans trying to say that thier planes were / are best ever and every one elses stink...blah blah blah......we won the war.....blah blah blah......we had ben afflick.....blah blah blah......
And is your reply your attempt to look like an idiot?
All Widewing has done is point out a possible discrepancy with one of the aircraft. No where in any of Widewing's post does he even allude to anything remotely you're accusing him of doing.
ack-ack
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Widewing's posts are amoung the most articulate and informed you will ever find on this BB. I always enjoy reading them.
He should consider changing his name to wisewing.
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Originally posted by Widewing
I can when the data flies in the face of physics...
By the way, if you wish to participate in a manly discussion, please change out of your tutu first. Inasmuch as you rarely have anything of substance to contribute, feel free to sod off.....
Widewing
Watch that blood pressure now... And if you're having fantasies of me in a tutu you should be more concerned about your own manliness, not to mention your sanity.
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Originally posted by Viking
Watch that blood pressure now... And if you're having fantasies of me in a tutu you should be more concerned about your own manliness, not to mention your sanity.
Just for the case you've missed it:
feel free to sod off...
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<--- will wear the tutu for $1000 for no longer than 30 mins if it will make you manly men play nice..
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Originally posted by Viking
Watch that blood pressure now... And if you're having fantasies of me in a tutu you should be more concerned about your own manliness, not to mention your sanity.
actually if you ever have anything inforamative keep us posted untill then please bore us with your sad diatribe and uninformed ignorance.
poor little fellow
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Here is the view of pilots of 415 Squadron Raaf - they flew the aircraft,they didn't google from the sofa- after exstensive flight trials of the Typhoon 1b in the middle east during 1943,they sum up.
"The general view was admiration for the Aircraft.The "likes" included 400mph level speed at 18500 altitude,a dive speed of 525 mph(Limited),the superb view out of the canopy,and light and sensitive controls."
At this juncture of history,451 Sqn commenced converting fully to spitfire mkVc
The three trials Typhoons were then ferried to 161 MU on 23rd of October 1943.
Actually all three of these Tiffies were operational during testing and sported dessert camo,maybe Kev would like to Skin one.:aok
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i'm sorry but i got very angry at what seems to be a general tendancy of this game to play down non american alied aircraft. Widewing is probably a sound bloke , and knows his stuff yet he wants to contadict what test pilots and actual combat pilots at the time say about it's perfomance in real combat.
the Mossie is a very much nuetered plane in this game yet if it was modeled CORRECTLY it would wipe the floor with most threats. but alas it would never happen . pitty
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Originally posted by B3YT
the Mossie is a very much nuetered plane in this game yet if it was modeled CORRECTLY it would wipe the floor with most threats. but alas it would never happen . pitty
flown correctly, it will do. :aok
just ask for 'Thrilla' or 'Rolex' to show you how its done.
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Originally posted by B3YT
i'm sorry but i got very angry at what seems to be a general tendancy of this game to play down non american alied aircraft. Widewing is probably a sound bloke , and knows his stuff yet he wants to contadict what test pilots and actual combat pilots at the time say about it's perfomance in real combat.
the Mossie is a very much nuetered plane in this game yet if it was modeled CORRECTLY it would wipe the floor with most threats. but alas it would never happen . pitty
I personally do not have any favorites. I very much enjoy the Brit aircraft and have no desire to undercut any.
However, I have a fair amount of experience with military aircraft and have researched the flight characteristics of many fighters.
Pilot reports can be accurate, but just as often completely inaccurate. Recorded data and test pilots are usually accurate, but not always. Especially in the 1940s where instrumentation errors were common. I can describe many instances where test pilots were deceived by malfunctioning instruments. Any report, regardless of author, that claims that the Typhoon had a critical Mach in excess of Mach 0.81 is flawed. NACA, who designed the 2219 wing used by the Typhoon states that the critical Mach of the wing section is Mach 0.70. A Typhoon could certainly exceed Mach 0.70, but did so with buffeting and eventual loss of control.
In the game, the Typhoon has virtually the exact same dive characteristics as the Tempest. However, the Tempest's wing was specifically designed to improve high Mach flight and control. The AH2 Typhoon doesn't even begin to buffet until Mach 0.77, which is well above where it should begin. Heck, I can dive an F4F-4 as fast as a Tempest... Go figure. Especially when the F4F-4 had an absolute terminal velocity of 483 mph. In AH2, you can get 601 mph! So, this issue is not isolated to the Typhoon.
My regards,
Widewing
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Naca ruined the P39,this was a 400mph aeroplane all be it without armour or Guns,till NACA made them remove the draggy turbo charger air intakes,and the Turbocharger with it!..P39 Naca'erd..lol
Thank God they didn't get hold of the P38,almost identical air intakes...Less draggy..I don't think so.;)
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Originally posted by Hazzer
Thank God they didn't get hold of the P38,almost identical air intakes...Less draggy..I don't think so.;)
I believe they were the ones responsible for those useless tail weights on the 38
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Originally posted by Hazzer
Naca ruined the P39,this was a 400mph aeroplane all be it without armour or Guns,till NACA made them remove the draggy turbo charger air intakes,and the Turbocharger with it!..P39 Naca'erd..lol
Thank God they didn't get hold of the P38,almost identical air intakes...Less draggy..I don't think so.;)
NACA is now known as NASA. They simply provided the research that helped design many of these planes. Blame the P39 on the USAAC and Bell.
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Originally posted by Widewing
I personally do not have any favorites. I very much enjoy the Brit aircraft and have no desire to undercut any.
However, I have a fair amount of experience with military aircraft and have researched the flight characteristics of many fighters.
Pilot reports can be accurate, but just as often completely inaccurate. Recorded data and test pilots are usually accurate, but not always. Especially in the 1940s where instrumentation errors were common. I can describe many instances where test pilots were deceived by malfunctioning instruments. Any report, regardless of author, that claims that the Typhoon had a critical Mach in excess of Mach 0.81 is flawed. NACA, who designed the 2219 wing used by the Typhoon states that the critical Mach of the wing section is Mach 0.70. A Typhoon could certainly exceed Mach 0.70, but did so with buffeting and eventual loss of control.
Pilot manual contradict this so who's right ?
Btw what is the Naca profile used by the Spitfire a know good diver ?
In the game, the Typhoon has virtually the exact same dive characteristics as the Tempest. However, the Tempest's wing was specifically designed to improve high Mach flight and control. The AH2 Typhoon doesn't even begin to buffet until Mach 0.77, which is well above where it should begin. Heck, I can dive an F4F-4 as fast as a Tempest... Go figure. Especially when the F4F-4 had an absolute terminal velocity of 483 mph. In AH2, you can get 601 mph! So, this issue is not isolated to the Typhoon.[/B]
this issue is also not related to the Typhoon.
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Until we are all running super computers flight models are NEVER going to be right.
Why do you think Boeing, Airbus, etc all spend $100,000s on computers for it, and not a couple of thousand on a home PC.
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Bell were outraged by what NACA and the AAF did to their aeroplane at wright field,but on the verge of financial collapse,their was nothing the company could do,they needed the Orders.
The prototype climbed to 20k,in 5 min's!
due too NACA's obsession with streamlining - due largley to underpowered radial engined Aircraft,they were used to dealing with-the P39 became a missed opportunity,or the Iron "DOG":)
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Kev the issue has nothing to do with the flight model, we can set critical mach where ever it should be.
The issue is simply about conflicting data sets, and where the critical mach should be. And that is not a simple question to answer.
HiTech
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Originally posted by B3YT
the Mossie is a very much nuetered plane in this game yet if it was modeled CORRECTLY it would wipe the floor with most threats. but alas it would never happen . pitty
No it won't. If a Mossie flown by a good stick encounters a Spitfire flown by an equally good stick and all the conditions are the same (i.e. co-alt and co-Energy) the Spitfire is going to beat the crap out of the Mossie. There are just some things no matter how good you are, just can't make the Mossie over come when it engages a single engine fighter on equal footing. However, if the Mossie had an advantage in altitude or Energy then things can work out differently.
ack-ack
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Originally posted by straffo
Pilot manual contradict this so who's right ?
Btw what is the Naca profile used by the Spitfire a know good diver ?
this issue is also not related to the Typhoon.
Straffo, I doubt that you could be objective in this discussion as you have long since been known as a "Tiffie dweeb" in Aces High. You like fast planes with cannons, best for cherry picking, I suppose.
Nonetheless, the fact is indisputable that the Typhoon and the Tempest have virtually identical dive characteristics in the game. They should not.
The Spitfire wing is a NACA 2213 at the root (12% thick) and a 2209.4 at the tip (6% thick).
The Tempest wing is a H/1414/37.5 at the root (14% thick) and a H/1410/37.5 at the tip (10% thick).
The Typhoon wing is a NACA 2219 at the root (18% thick) and a NACA 2213 at the tip (12% thick).
Critical Mach limits for the above aircraft should be in the order presented, as indicated by the chord to thickness ratios.
My regards,
Widewing
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Originally posted by Widewing
Straffo, I doubt that you could be objective in this discussion as you have long since been known as a "Tiffie dweeb" in Aces High.
I try to be objective , please note that I didn't jump on you screaming and drolling and I just made you notice (and I was not alone) that your comment was in conflict with pilot manual.
You like fast planes with cannons, best for cherry picking, I suppose.[/B]
I'm a tiffie dweeb for a lot of reason all historical ,nothing related to the capabilities of the tiffie ,I'm just a 2ndTAF fan living in Normandie where it operated and where a lot of 2ndTAF pilots are buried.
See my love for the typhoon as a tribute to the young man who lost their lives helping my country to be free again.
Also as we never met online I think you can stuff your comment about my cherry picking abilities in your favorite place (see when I'm pissed I start easily to be incorrect).
Nonetheless, the fact is indisputable that the Typhoon and the Tempest have virtually identical dive characteristics in the game. They should not. [/B]
I've not the Tempest pilot notes (well it should be buried in some unknown place) I can't invalidate or confirm your opinion.
But as far as I remember the change made to build the Tempest where not because of the inabilities to dive of the Typhoon ,I'll try to make a list later.
The Spitfire wing is a NACA 2213 at the root (12% thick) and a 2209.4 at the tip (6% thick).
The Tempest wing is a H/1414/37.5 at the root (14% thick) and a H/1410/37.5 at the tip (10% thick).
The Typhoon wing is a NACA 2219 at the root (18% thick) and a NACA 2213 at the tip (12% thick).
Critical Mach limits for the above aircraft should be in the order presented, as indicated by the chord to thickness ratios.[/B]
That narrow it , on (and last question) what profile is used on the P47 ?
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Originally posted by straffo
I try to be objective , please note that I didn't jump on you screaming and drolling and I just made you notice (and I was not alone) that your comment was in conflict with pilot manual.
I'm a tiffie dweeb for a lot of reason all historical ,nothing related to the capabilities of the tiffie ,I'm just a 2ndTAF fan living in Normandie where it operated and where a lot of 2ndTAF pilots are buried.
See my love for the typhoon as a tribute to the young man who lost their lives helping my country to be free again.
Also as we never met online I think you can stuff your comment about my cherry picking abilities in your favorite place (see when I'm pissed I start easily to be incorrect).
I've not the Tempest pilot notes (well it should be buried in some unknown place) I can't invalidate or confirm your opinion.
But as far as I remember the change made to build the Tempest where not because of the inabilities to dive of the Typhoon ,I'll try to make a list later.
That narrow it , on (and last question) what profile is used on the P47 ?
I'm not presenting an opinion. It is a fact that the critical Mach of the Typhoon was substantially less than that of the Tempest. The relative chord to thickness ratios makes that evident.
As to the P-47, it used a Seversky/Republic S3 wing at the root (15% thick) and the tip (8% thick).
Edit: Added comparison of S-3 profile with NACA 2219 overlay for comparison.
(http://home.att.net/~c.c.jordan/S-3_2219.jpg)
My regards,
Widewing
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To summarize:
Originally posted by Widewing
Placarded maximum permitted dive speeds at 10k are as follows:
P-47D: 500 mph IAS
P-51D: 500 mph IAS
P-38L: 440 mph IAS
F4U-1D 443 mph IAS
F6F-5: 449 mph IAS
Typhoon: 525 mph ( no altitude given)
Tempest : 540 mph (10k)
and:
Originally posted by dtango
Don't mistake compressibility effects with critical mach number. Critical mach number is the point that supersonic flow occurs on the wing at some point. This doesn't mean that shockwaves have formed and are strong enough to cause significant separation of flow which leads to compressibility effects on control.
For stability and control issues to occur the shockwaves have to reach a point that causes enough premature flow separation behind them that impacts the tail. This flow separation creates the compressibility effects we are aware of e.g. a) buffeting - because the downwash from the wing on the tail subjects the tail to extremely turbulent flow due to the separated flow, b) tuck under - because the downwash from the wing is reduced which increases the angle of attack on the tail, c) loss of pitch authority - because of elastic deformation on the tail boom which reduces the effectiveness of the elevator.
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Originally posted by hitech
Kev the issue has nothing to do with the flight model, we can set critical mach where ever it should be.
The issue is simply about conflicting data sets, and where the critical mach should be. And that is not a simple question to answer.
HiTech
I guess that settle it.
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Originally posted by Hazzer
Naca ruined the P39,this was a 400mph aeroplane all be it without armour or Guns,till NACA made them remove the draggy turbo charger air intakes,and the Turbocharger with it!..P39 Naca'erd..lol
Thank God they didn't get hold of the P38,almost identical air intakes...Less draggy..I don't think so.;)
You're perhaps confusing the radiators on the P-38 with air intakes for the engine, since they look somewhat similar to the air intake on the side of the XP-39. The P-38 does not have large air scoops to take in air for the engines anywhere. The scoops under the propeller cowls are for the oil coolers, and on the late models, for the oil coolers and the chin mounted core type intercoolers. Those large scoops on the sides of the tail booms at the back are for the radiators.
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Originally posted by Murdr
I believe they were the ones responsible for those useless tail weights on the 38
Actually, although I'd have to look it up, I think it was actually a general who forced the installation of the goofy counter weights on the elevators, because he was convinced the compression effects were actually "tail flutter" (I could be wrong, going off memory here). The elevators actually have counter weights built into them internally, in the form of structural bracing and thicker skin. Kelly Johnson said the only thing the external weights did was possibly injure or kill pilots who bailed out.
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Originally posted by Hazzer
Bell were outraged by what NACA and the AAF did to their aeroplane at wright field,but on the verge of financial collapse,their was nothing the company could do,they needed the Orders.
The prototype climbed to 20k,in 5 min's!
due too NACA's obsession with streamlining - due largley to underpowered radial engined Aircraft,they were used to dealing with-the P39 became a missed opportunity,or the Iron "DOG":)
While NACA provided the drag data and the streamlining data, it was the USAAC that decided the turbo inlet scoop probably caused more drag than the turbo made up for in horsepower. POSSIBLY at altitudes BELOW 12,000 feet, that was true, or at least close to a toss up. Now, ABOVE 15,000 feet things were VERY different. But remember, it wasn't until the original P-39 orders were taken that it was discovered that a lot of fighting was starting to happen ABOVE 15,000 feet.
Also, it must be stated that turbochargers were in short supply, and between the P-38 and the P-47, and other planes using them, it was all GE could do to make enough of them. Further, as power went up later in the war, even the P-38 had to be modified to make room for a big enough intercooler to make the turbocharger effective and reliable at higher power levels. By 1943, they'd have been looking for a place to put a much bigger intercooler on the P-39.
At altitudes of 12,000 or less, the P-39 isn't so much of a dog as many would believe.
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There were indeed supply problems with the turbochargers, GE was making them as fast as they could, and the Army had to decide which combat a/c to give priority too, and that ended up being the bombers, like the B-17, and some fighters like the P-38 (intended as a high alt fighter from the start). By the time the problem started being addressed the war had already begun in the Pacific, and the P-39Ds went as they were. Hindsight is always 20/20 I guess.