Typhoon critical mach modelling correct or incorrect

[Kev367th]

Originally posted by Stang
We need to get the detatchable tail section too.

Well -
Only the early Tiffys suffered from that problem.

[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....

[Souless]

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.

[Squire]

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.

[Widewing]

Originally posted by Squire
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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

[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.

[Stoney74]

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.

[Squire]

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.

[Widewing]

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

[dtango]

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



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

[TimRas]

For comparison, Tempest V dive limits:

[Viking]

Again Widewing, the intardnet-historian, is disputing professional test pilots and controlled test dives with mach meters.

[Stoney74]

Originally posted by TimRas
For comparison, Tempest V dive limits...

I don't suppose the Typhoon POH has an altitude chart such as this?

[1K3]

Not only that, AH Typhoon is too fast!

Max speed of Typhoon at WEP at...9 lbs at 3700 rpm


AH Typhoon's speed at WEP (9 lbs at 3700 rpm...)

[1K3]

The AH Typhoon climb rate  rate is somewhat conservative...