Author Topic: P-38 Stall performance (Read 353 times)

BigCrate · « **on:** February 20, 2002, 11:59:20 PM »

This is a quote from a 1972 November issue of AirPower magazine.

"The P-38, with its contra-rotating propellers, was probably the GENTLEST aircraft in a vertical turn of any WW2 fighter. A single
engine fighter, when pulled too tightly into a turn and stalled
would FLICK savagely over the top and try its damnest to spin.
The 38 with no torque to contend with didn't flick over the top.
When finally sucked so tight it stalled, it would simply mush outward. If back pressure on the stick were relaxed SLIGHTLY, it would immediately start flying again. No, or very little alt loss was experienced in this situation, a most UNUSUAL feature for a fighter."

Now I'm not trying to squeak about anything here. But I flew the
Spit9 some today and that damn plane won't stall/spin for chit.
Then I upped in a 38 flew it some it stalled very easily and almost everytime I stalled it tried to spin.
Now saying that IF i relaxed back pressure on the stick it would start flying again. Just like the article said. But 38 stalls/spins are horrible!! They are nothing like what the article I posted stated.
Now the spits are single engine fighters thus they have torque to contend with. And I don't see nothing to show the torque when you are slow say 100ish. What I saw in the spit9 is some what the article descibed happen for the P-38. It was suck so tight it stalled (didn't try to spin)and if back pressure was relaxed it start to fly. What i'm asking is just have a look at the stall performance of the P-38. Oh I think when the author said FLICK or FLICKER
i think he meant buffet. theres something to think about to.

PS anyone know where I can get old AIRPOWER magazies??
I knew a place a few years back but they have done closed down.

Cw
=Twin Engined Devils=

Tac · « **Reply #1 on:** February 21, 2002, 11:04:53 AM »

Yeah, in AH you have to WORK at stalling a single prop fighter.. you have to pull very hard or get below 100mph and pull hard.

I think the combat trim does that. Im not sure.

The pre-FM change planes behaved much more realistically in stalls imo (but not in E-retention..hehe, I remember the planes bled 300mph just turning 45 degrees at low g's lol!), the f4u would stall REAL bad if you didnt chop throttle on the top part of a loop.. now you can even WEP the damn thing at 100mph and very little torque is felt.

FLS · « **Reply #2 on:** February 21, 2002, 11:10:48 AM »

Flick probably refers to a flick roll, also known as a snap roll. It's caused by one wing stalling first then the lift from the other wing rolls the aircraft. The direction of the roll is a response to the direction of prop rotation. If you snap roll on purpose you can use rudder to increase the roll rate and control the direction of the roll.

If you stall the AH Spit IX in a right turn it will snap roll left away from the turn. In a left turn it rolls left into the turn on the stall.

The AH P-38 will roll into the turn in either direction but it's easy to catch. Compared to the Me 109, FW 190, or A6m5 it seems to me that it rolls less and recovers more easily. I don't know why the P-38 rolls on the stall in a vertical turn in AH. Something in the FM is rolling it and it's not the engines. Whether it's accurate or not I can't say.The AH FM is very nice for a PC. I doubt any PC based flight sim will ever fly exactly like the real aircraft. Still it would be interesting to know where that roll comes from.

--)-FLS----
Musketeers

BigCrate · « **Reply #3 on:** February 21, 2002, 12:35:14 PM »

If you knew where the roll comes from you could correct it to some degree I think. But still how could a single engine spit have better stall performance than the 38?? The wing config.???

Cw
=Twin Engine Devils=

FLS · « **Reply #4 on:** February 21, 2002, 01:50:06 PM »

I don't think the stall performance of the Spit vs the P-38 was a big concern in WW2. In any case in AH the Spit does snap roll out of the turn while the P-38 does not, just as the text describes. In a stall speed scissors the Spit will drop a wing while the P-38 is still controllable so I have to disagree that the P-38 stall is worse than the Spit in AH. Compare a hammerhead in the P-38 with any single engine fighter and it's obviously easier to control.

Why the AH P-38 rolls in a stall is an interesting question but I'm not convinced it's a problem. It may be a shortcoming of the FM or it may be a fuel distribution weight issue, a fuselage/engine nacelle masking airflow to the wings issue, an anecdotal story not quite reporting the facts issue, or more likely something that hasn't occurred to me. Maybe Hitech will tell us.

--)-FLS----
Musketeers

HoHun · « **Reply #5 on:** February 21, 2002, 02:11:37 PM »

Hi Bigcrate,

>Oh I think when the author said FLICK or FLICKER
i think he meant buffet.

"To flick" is the British aviation term for "to snap" and means asymmetrically stalling the wings. "Flick rolls" and "snap rolls" are very quick (and violent) manoeuvres caused by one wing losing most of its lift due to asymmetrical airflow over the aircraft. In that way, snap rolls are closely related to spins, and an unintentional snap roll often lead to an uncontrolled spin.

All of the WW2 fighters could snap roll (and spin), but as it was an asymmetric flight condition, asymmetric propeller slipstream like on single engined aircraft increased the danger of unintentionally entering a snap roll in a low-speed stalling situation.

The P-38 with its symmetric propeller slipstream reputedly was quite safe at the stall, but twin-engined aircraft actually held an advantage in that situation, anyway.

Another safety factor against unintentional snap rolls and spins were independendly-deployed leading edge slats like the Messerschmitts and the Lavochkins had. Asymmetric loss of lift would be countered by asymmetric slat deployment, keeping the aircraft from going into a spin.

Regards,

Henning (HoHun)

Naudet · « **Reply #6 on:** February 21, 2002, 04:38:56 PM »

Bigcrate, i dunno how long you fly AH, but your problem with stalls might be that you are pulling to hard.

In my 1st 3-4 weeks, i would stall any plane in AH in every turn, loop etc.. When i got used to the FM, i was able to fly anything without stalling it, and now a stall is the rarest thing i ever have.

And about the P38's stall. I find it very very easy to recover. The P38 is for me the easiest plane to go over-the-top, any other vertikal maneuver. But this is only the case, when not using the combat trim.
I noticed that in most AH planes, the CT will make slow speed turning and vertikal reversals more difficult. This is because the CT is only working properly between 200-400 mph. Below 200 you will fly the plane constantly out of trim, but the CT will nevertheless do some retrimming. And this retrimming will cause some plane movements you dont want to see.
So maybe just try to fly it without CT.

BigCrate · « **Reply #7 on:** February 22, 2002, 01:16:33 AM »

What was the stall speed of the 38?? With flaps down and with out flaps down..

Cw
=Twin Engined Devils=