P39 Anti-Spin Chutes?

[Randy1]

I ran across this report on spin test on the P39.
http://www.wwiiaircraftperformance.org/P-39/P-39Q_Spin.pdf

It notes spin chutes were added to each wing.

Anybody know how they were to work?

[Krusty]

They create a ton of drag and stop a spin, thus creating a downward fall and bring the nose down.

From there you jetison the chutes and recover normally.

They are used for spin testing in case a spin is totally unrecoverable, because otherwise spin testing would be suicidal.

[Randy1]

Krussty, in the test the P39, even with spin chutes did not recover from a power on stall to the left.  The guy had to bail.  I wonder how big the chutes were?

[Krusty]

Some planes are just deathtraps to spin. P-39s had a very bad spin once you let it really dig into the spin. If you didn't recover in 2 (or was it 4?) oscillations you would never do so.

P-51s historically had NASTY spins, so much they were ordered to bail immediately in the pilot manual if the plane spun, as it was unrecoverable. Paraphrasing here, but something like that. This is not just with a full aux tank, either. In here it's much more docile. Most planes don't experience the right amount of torque it seems. Especially F4Us at slow speeds.

But, spin recovery chutes were still used for tests, simply because they wouldn't know until they tried it. Even if it didn't work, the chance that it WOULD work was worth putting them onto test aircraft. That's how they figured out how planes in WW2 flew: they wrecked them.

[Randy1]

Thanks for the information Krusty.

[colmbo]

P-51s historically had NASTY spins, so much they were ordered to bail immediately in the pilot manual if the plane spun, as it was unrecoverable. Paraphrasing here, but something like that. This is not just with a full aux tank, either. In here it's much more docile.

I just read the section on spins in my P-51 manual, here's a quote of the first line "Power-off spins in the P-51D are safe enough if you have plenty of altitude for recovery."  It also points out that spins with power are extremely dangerous and should never be performed intentionally.  Reference the power on spin "if you should ever get into a power spin, cut the throttle immediatelly and follow normal recovery procedure."...... "you may lose as much as 9000 feet of altitude"

The only mention it makes of bailing out is that you "fix in your mind the altitude at which to bail out, and bail out before it is too late"

Your statement that the Mustang is unrecoverable and you should bail seems to not be accurate.

[Randy1]

http://en.wikipedia.org/wiki/Spin_%28flight%29

. . .Soviet pilots did numerous tests of the P-39 and were able to demonstrate its dangerous spinning characteristics. Bell then issued a recommendation to bail out if the airplane entered a spin. North American P-51 Mustangs with auxiliary fuel tanks not originally designed for the P-51 suffered from the same problem. Similarly, the Vought F4U Corsair was reputed to have appalling stall and spin recovery characteristics, even in the "clean" (no stores) configuration.

Could be there was a particular model variant of the 51 that suffered bad spin problems.

[Chalenge]

Randy, the F4U had a similar chute installed in the tail cone during flight testing. Boone Guyton reported that the F4U would kill any pilot that spun the plane more than one rotation to the left. He tried it only once and even with all of his strength could not move the stick one bit. Fortunately, a spotter calmly reminded him about the recovery chute and he survived the ordeal.

On another note, he also got chewed out because he failed to recognize a fatal flaw in the cockpit layout. There was a valve in the cockpit that allowed combat pilots to fill the fuel tanks evacuated volume with CO2, so that fires could be avoided if the tank were hit. Unfortunately, there was also a duplicate valve for emergency landing gear blow down. One man in the Solomon Islands triggered the gear when he meant to use the CO2. No power on earth could get the gear back up and he was shot to pieces by the Zekes.

[Randy1]

Chalenge, it would be so interesting to see notes taken during plane design meeting.  So many details to resolve.

I was a design project engineer on nuclear power plants.  I can tell you the battle against design assumptions was arduous.

Thanks for the interesting post on the F4U.

[Stellaris]

Interesting statisticoid.  If the US Airforce today had the accident rate it had in 1950, it would be destroying aircraft faster than they could be manufactured.  I'm sure that's broadly true of any modern air force, and more generally, for the front line kit of any modern army or navy.  Of course all those weapons are vastly more lethal than their antique counterparts, but that only makes the problem worse should they come into serious combat.  The first week of WWIII will look like Star Wars.  The second week will look like Braveheart.

[danny76]

Interesting statisticoid.  If the US Airforce today had the accident rate it had in 1950, it would be destroying aircraft faster than they could be manufactured.  I'm sure that's broadly true of any modern air force, and more generally, for the front line kit of any modern army or navy.  Of course all those weapons are vastly more lethal than their antique counterparts, but that only makes the problem worse should they come into serious combat.  The first week of WWIII will look like Star Wars.  The second week will look like Braveheart.

everyone will be painted blue?

[earl1937]

Thanks for the information Krusty.

Randy, all I can tell you about the P-51K, which is the same as the D model, except for instrument placement on panel, a 'tweaked" engine and a slightly larger dorsal fin and a few other differences, but airframe was basically the same. After 464 hours in the K in the reserve, I have spun the 51 many times in the interest of losing altitude fast for what ever reason I had at the moment, and never experienced any unusual spin recovery problems. We were taught to use the same recovery procedures as in a T-6, stick forward, opposite rudder to the spin and after about 1 and 1/2 turns, it would stop spinning, then a little back pressure on stick and you are back in level flight.
In talking with "Bob" Matterson, who flew 31 missions over Germany during the big war, he use to speak of getting the 51 in unusual attitudes and stalling, but recovery was normal, you just had to have some altitude under you to recover. The most dangerous flight realm was an "accelerated" stall. You wanted to avoid those because the Laminar flow wing on the ponie had to attain a certain AOA before it would start flying again. The trick was to learn how to get the wing back to below the critical angle of attack. Difficult to describe how to , but it was not a pleasant experience and something I avoided, because I was never in a combat situation, but I guess the guys in WW2 and Korea did run into that occasionally.

[Randy1]

Earl, that is really interesting.  I had no idea you had flown the Mustang.  That is just nifty.  On the K did they move the speed and altimeter higher on the panel?

[earl1937]

Earl, that is really interesting.  I had no idea you had flown the Mustang.  That is just nifty.  On the K did they move the speed and altimeter higher on the panel?

First with the standard "T" congf. Actually, I think the F-82 was also one of the first fighters produced with the "T" confg for flight instrument layout. That was a long time ago, and if anyone knows different, please post correction to me!