Strange P-39 stall - finally caught on film.

[Ack-Ack]

You'd better listen to him guys, his uncle taught him all about the permeability of the Heinkel Do 152, and he knows his stuff. He was a P82 pilot over Japan, after all.

Sadly, said uncle grabbed the short straw on the day they were looking for P-82 pilots to test out the new AAA gun the US Army got.


ack-ack

[Puck]

A film could be semi-permeable, for example, and allow air or gasses to pass through it, but not water.   

Some minds are also semi-permeable.  Anything resembling information is blocked at the outer membrane.

Speaking of P-39 handling, I've read (in more than one place) that the P-39 Bell delivered to Dayton wasn't too bad, but after the boys at Wright-Patterson started putting their mark on the beast it turned into a...well...iron dog.  Any truth to this?

[Soulyss]

Some minds are also semi-permeable.  Anything resembling information is blocked at the outer membrane.

Speaking of P-39 handling, I've read (in more than one place) that the P-39 Bell delivered to Dayton wasn't too bad, but after the boys at Wright-Patterson started putting their mark on the beast it turned into a...well...iron dog.  Any truth to this?

I just got a book for Christmas that details the P-39's development but haven't gotten to reading it yet.  The prototype was delivered with a supercharger that would have helped the P-39 sustain engine performance at higher altitudes, the army decided to remove it.  This limited that critical altitude of the aircraft.   There was a decent article on the subject that I read awhile back, unfortunately the details and the URL escape me at the moment.  

*edit*
I think this was it http://home.att.net/~C.C.Jordan/XP-39.html.

[Boozeman]

Wow, 1 troll enters the stage and the whole thread goes down the drain. 

 

[Boozeman]

Looking at the film but without the benefit of all the information (stall horn, control inputs, etc.) I would say that you just got into an accelerated stall.  It's happened to me more times than I'd care to admit to, and I think if you had more room a normal stall recovery would have worked.  Get the nose down, built some speed and pull out. 

Thats the problem. The nose is already pointing down, and there is enough airspeed for a pullout - but the plane does not react to any control input.

[Baumer]

Boozeman, I noticed you had your flaps out. The game "seems" to be very touchy when recovering from a stall with the flaps out, even when you are nose down with speed (especially if you have combat trim on).

I've seen this in several planes, not just the P-39, so in my opinion it's best to get the flaps up asap when recovering from stall. I know that's not always an easy thing to do, but it makes it seems to make recovering easier.

[palef]

It's a shame Earl's not here to put all the P39 rumours to bed.

[Boozeman]

Thanks for the input Baumer, but I don't think that the flap/combat-trim combination is the reason for that strange stalling behavior.

Here i have another film, finally I could recreate it offline. I still have no idea what triggers this stall. On this film I have made 3 stalls:

http://www.netcologne.de/~nc-vreckova/stallop1.ahf

1. 1 notch flap, combat-trim, all the way through stall and recovery. Using the standard technique (rudder opposite to spin, cutting throttle) recovery was quite easy.
2. No flaps, combat-trim, all the way through stall and recovery. Here I just used opposite rudder, full throttle. As the plane picks up speed when the nose points down, full control returns and i can pull out without any problem.
3. No flaps, no CT, plane trimmed for level flight. The onset of the stall is very similar to stall 2, but then...well see yourself - as the nose points down, all controls are gone. It actually looks like I'm lawndarting on purpose...but I'm desperately trying to avoid it. What I hit the ground the plane does 230 mph! At that speed it should have already plenty of authority on every control surface, but there was absolutely none.     

[MiloMorai]

I just got a book for Christmas that details the P-39's development but haven't gotten to reading it yet.  The prototype was delivered with a supercharger that would have helped the P-39 sustain engine performance at higher altitudes, the army decided to remove it.  This limited that critical altitude of the aircraft.   There was a decent article on the subject that I read awhile back, unfortunately the details and the URL escape me at the moment.  

*edit*
I think this was it http://home.att.net/~C.C.Jordan/XP-39.html.

All Allison V-1710 a/c engines had a supercharger. Whatl all V-1710 engines did not have was a turbocharger.

[Soulyss]

All Allison V-1710 a/c engines had a supercharger. Whatl all V-1710 engines did not have was a turbocharger.

That's what I meant.

[Ghastly]

When Jerry Collinsworth spoke at the Warbirds convention, he told us of his experience with the P39 unexpectedly departing during training excercises and spinning down 6000 ft before he recovered it - just barely off the deck. He said that he gained a bit of local notoriety - he was the first person in their group to recover a spin in it from such a low altitude - everyone else who'd done so had gone in.    He had nothing good to say about the aircraft.

(Purely anecdotal of course)

<S>

[Ack-Ack]

It must be a love/hate thing with the P-39 and those that flew it.  There was an AW player that used to fly the P-39 in the MTO, mostly doing convey duty if I recall correctly.  He had nothing but good things to say about the P-39 and if I also recall correctly, enjoyed it more than the P-47 and P-38 (he flew those as well in the MTO, one of the P-47 skins in AH, "Viking" was the P-47 he flew in WW2).


ack-ack

[HPriller]

"at 1300 RPM the drive shaft tickled your balls" - my grandfather who flew p39's, among other things.

[Soulyss]

It must be a love/hate thing with the P-39 and those that flew it.  There was an AW player that used to fly the P-39 in the MTO, mostly doing convey duty if I recall correctly.  He had nothing but good things to say about the P-39 and if I also recall correctly, enjoyed it more than the P-47 and P-38 (he flew those as well in the MTO, one of the P-47 skins in AH, "Viking" was the P-47 he flew in WW2).


ack-ack

There's some truth to that, some pilots loved how it handled, other hated it.  Pilots in New Guinea and the Solomons hated it because it couldn't climb to altitude in time to intercept incoming raids, but the Soviets loved it, couldn't get enough of them.

[Raptor]

In Alaska pilots thought Thomas McGuire was hot stuff because he did a loop in a P39. P38 seemed like a hotrod in comparison when switching over.