Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Boozeman on January 03, 2010, 04:09:15 PM
-
From time to time when flying the P-39, there is this weird stall that is almost unrecoverable - maybe some of you have also experienced it. Problem is, when i want to recreate it on purpose, I can't. I just can get the usual stalls like on most other aircraft, short and violent, but easy to recover. THis stall is different though. When in it, all controls are dead - pretty much like those stalls on the Mossie and 152, when they tumble down like a leave with zero airspeed. However, in this case the plane has enough airspeed, close to 200, but still dead controls.
So here is it, in all it's dreaded beauty:
http://www.netcologne.de/~nc-vreckova/p39stall.ahf (http://www.netcologne.de/~nc-vreckova/p39stall.ahf)
As you can see at 0:43, the stall sets on at about 200 mph, flips the plane a little, and then it drops like a stone all the way to the ground. Normally at this dive angle and speed, you can easily pull out... but not with this one - no reaction to elevator, rudder or aileron inputs.
Here is a another film:
http://www.netcologne.de/~nc-vreckova/p39stall2.ahf
Pretty similar to the first film. Wing flips at about 210 mph, controls go dead for about 2 seconds. As suddenly as they dissappeared, as suddenly they were back though. But one still think why did they go out in the first place?
Any comments on this matter or the films?
-
It looked like when you hit 200, you started to get lit up. is it possible you could of lost your stab or tail even? otherwise, i got no idea.
-
Historically the P-39 was considered by many to a very tricky and demanding plane to fly, the pilot had to be really careful and deliberate on the controls or enter an accelerated stall. There are certainly parts of Aces High's P-39 flight envelope that will bite you if you're not very very smooth and careful on the controls
It also had the somewhat controversial reputation to tumble, combat pilots certainly felt that it would and could however Bell test pilots apparently could never replicate it under test conditions.
Charles King of the 39th Fighter Squadron flew P-39's and P-400's in New Guinea and had the following to say.
The P-39's handling characteristics have also come in for some criticism too. However, I am convinced that the fighter did not "tumble", as been widely reported. All tests to record a tumble were unsuccessful. It was easy to stall the airplane on it's back, with a resultant flat inverted spin. In that situation, retarding the throttle would allow the aeroplane to drop into an easily recoverable normal spin. Loss of altitude was minimal, but to a disoriented pilot with a control stick that seemed useless, this was not apparent. The aeroplane oscillated slowly and horizontally as the noes dipped below the horizon and then rose above it. To some pilots this was interpreted as a tumble.
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.
-
From time to time when flying the P-39, there is this weird stall that is almost unrecoverable - maybe some of you have also experienced it. Problem is, when i want to recreate it on purpose, I can't. I just can get the usual stalls like on most other aircraft, short and violent, but easy to recover. THis stall is different though. When in it, all controls are dead - pretty much like those stalls on the Mossie and 152, when they tumble down like a leave with zero airspeed. However, in this case the plane has enough airspeed, close to 200, but still dead controls.
So here is it, in all it's dreaded beauty:
http://www.netcologne.de/~nc-vreckova/p39stall.ahf (http://www.netcologne.de/~nc-vreckova/p39stall.ahf)
As you can see at 0:43, the stall sets on at about 200 mph, flips the plane a little, and then it drops like a stone all the way to the ground. Normally at this dive angle and speed, you can easily pull out... but not with this one - no reaction to elevator, rudder or aileron inputs.
Here is a another film:
http://www.netcologne.de/~nc-vreckova/p39stall2.ahf
Pretty similar to the first film. Wing flips at about 210 mph, controls go dead for about 2 seconds. As suddenly as they dissappeared, as suddenly they were back though. But one still think why did they go out in the first place?
Any comments on this matter or the films?
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
:huh
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
:headscratch: :huh :confused:
-
after the plane stalls
-
Do you mean compression? That's what happens when your plane's controls seem to 'lock up' at high speeds.
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
You're talking about 'compressability', as permeability isn't a word to the best of my knowledge and no, the Ta 152 didn't suffer from compressability like the P-38 or the P-47 did.
ack-ack
-
Permeability is a word, but I'm not sure how it would be applicable here.
We measure the permeability of the food packaging we make at work. In other words, we measure how much, and of what, can pass through our film. A film could be semi-permeable, for example, and allow air or gasses to pass through it, but not water. :old:
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
:huh
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
Not only are you wrong but WTF does it have to do with the p-39?
P.S. spelling... it's just a click away.
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
:O :huh :uhoh :headscratch: :rolleyes:
-
acually the 152 goes into permeabillity which mean it aproaches mach 1 and the aircraft of ww2 controle surfaces weren't designed for such speeds
I suggest a Google search on Permeability.... Or, even a check of Wiki: http://en.wikipedia.org/wiki/Permeability (http://en.wikipedia.org/wiki/Permeability)
My regards,
Widewing
-
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.
-
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
-
A film could be semi-permeable, for example, and allow air or gasses to pass through it, but not water. :old:
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?
-
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 (http://home.att.net/~C.C.Jordan/XP-39.html).
-
Wow, 1 troll enters the stage and the whole thread goes down the drain. :aok
:banana: :banana: :banana:
-
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.
-
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.
-
It's a shame Earl's not here to put all the P39 rumours to bed.
-
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 (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.
-
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 (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. ;)
-
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. :)
-
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>
-
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
-
"at 1300 RPM the drive shaft tickled your balls" - my grandfather who flew p39's, among other things.
-
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.
-
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.
-
It also had the somewhat controversial reputation to tumble, combat pilots certainly felt that it would and could however Bell test pilots apparently could never replicate it under test conditions.
Eventually Bell sent a test pilot and technician to Russia to deal with the very loud and angry gripes of the Russians using the P-39, and a Russian pilot promptly took up a P-39 and demonstrated the dreaded flat spin that had been plaguing them constantly. The technician, enlightened, did an investigation into how the Russians were loading them up and discovered that they were flying them nose-light- after the heavy ammo for the 37mm gun was expended. They even had a note in the manual somewhere that the nose should be filled with a box of empty shells for transfer flights, to give it some ballast. That solved the dreaded flat spin, to a degree, but even after that the P-39 was always prone to very, very nasty stalls.
-
Boozeman,
Spit 5 suffers a similar nose down stall like that one there. Problem is your not fast enough to pull up that hard. In that situation I dont suggest you do that again your nose was already going up, you can change your angle a bit then pull nose up when the 38 pulls for the shot.
other dude needs more time in a 152 I think :D
-
Junky, you may want to take a look on my 3rd film, some where on page 2. In that case, my airspeed was well over 200 (230 in fact when i crashed) and still no elevator authority. At that speed, you should be able to make a pullout.
But thanks for the Spit5 tip, i'll check it out.
-
wooowooo you were at 200 when that stall happened? bloody hell then I got no answer for you :D :salute
-
Junky, you may want to take a look on my 3rd film, some where on page 2. In that case, my airspeed was well over 200 (230 in fact when i crashed) and still no elevator authority. At that speed, you should be able to make a pullout.
But thanks for the Spit5 tip, i'll check it out.
[/quote230 thats wierd
tbms some times stall out and the elevator stays in nose down position any tips
-
Junky, you may want to take a look on my 3rd film, some where on page 2. In that case, my airspeed was well over 200 (230 in fact when i crashed) and still no elevator authority. At that speed, you should be able to make a pullout.
But thanks for the Spit5 tip, i'll check it out.
[/quote230 thats wierd
tbms some times stall out and the elevator stays in nose down position any tips
If you stall out a TBM, you're pulling on the stick too hard and entering into an accelerated stall. Go to the TA and have a trainer work with you on BFM (Basic Flight Maneuvers) so you'll be able to turn a plane without stalling it in.
ack-ack
-
my question in a quote was an accident