Roll Rate revisited - P39 v P40

[Venturi]

I just tested at the conditions on the chart, 10,000' and at 230mph IAS. It takes the P39 3 secs to roll right.. 4secs to roll left. The P40 takes 4.5sec to roll right, 4sec to roll left. Try for yourself, it may be that the P39 is too good, rather than the P40 too bad. 4 sec is about right (90deg / sec)

 

Or it may be that the P40 should be about where the P39 is now (3.5-3.75 sec)

 

Edited April 3, 2018 by Venturi

[JtD]

P-40 below reference data, P-39 above. Same old, same old. Short of the original Il-2 Bf109G-2, there's no other aircraft I despise as much as I despise the P-39. For this very reason.

[KoN_]

Need a few tips on the P39 and P40 in mixture and RPM settings cooked on take off and combat , to start off with but slow manged not too cook but feel not getting the best from the P39 tends to flip to the left  on a tight turn loose speed very quickly . 

[56RAF_Roblex]

29 minutes ago, II./JG77_Con said:

Need a few tips on the P39 and P40 in mixture and RPM settings cooked on take off and combat , to start off with but slow manged not too cook but feel not getting the best from the P39 tends to flip to the left  on a tight turn loose speed very quickly . 

 

P40 in particular is easy to cook on take-off if you follow the usual procedure used on most fighters ie 'Give it everything you have and throttle back once you are settled in the climb.'   You cannot really use more than 3000rpm and 40-45 manifold on take-off.   Full rpm & full manifold only lasts about 60 seconds so the engine will blow very soon after you lift your wheels. as soon as you are up and at 150 reduce the throttle smoothly to 37 and then reduce the rpm to 2500-2600 for the initial climb.   Continuous will allow you to go up to nearly 40 but it is best to treat it gently so soon after take-off power has been used.

 

P-39 should not flip unless you are going too slow.  Never drop below 180mph (about 300kmh)  in the combat area.  In the circuit 140mph is OK on the downwind & base legs because you should not be pulling high G turns.

[KoN_]

13 hours ago, 56RAF_Roblex said:

 

P40 in particular is easy to cook on take-off if you follow the usual procedure used on most fighters ie 'Give it everything you have and throttle back once you are settled in the climb.'   You cannot really use more than 3000rpm and 40-45 manifold on take-off.   Full rpm & full manifold only lasts about 60 seconds so the engine will blow very soon after you lift your wheels. as soon as you are up and at 150 reduce the throttle smoothly to 37 and then reduce the rpm to 2500-2600 for the initial climb.   Continuous will allow you to go up to nearly 40 but it is best to treat it gently so soon after take-off power has been used.

 

P-39 should not flip unless you are going too slow.  Never drop below 180mph (about 300kmh)  in the combat area.  In the circuit 140mph is OK on the downwind & base legs because you should not be pulling high G turns.

Yes that 60 second rule is what's getting me on first two take offs . I'll keep an eye on manifold pressure . I'll let you know how I get on . Thank you .

[ICDP]

Back on topic.

 

The chart from AHT does show the devs got it wrong.  As much as I hate to say it guys, it looks like the FM guys are just pretty poor at getting relative roll rates correct.  No, reports I have read states a LaGG-3 or La5 has a roll rate similar to an Fw190, or La5FN should out roll an Fw190.

 

I know people will say, the devs don't need to justify their choices and may have super secret flight reports.  This is not a valid response to be honest and justifies nothing.

[=362nd_FS=Hiromachi]

Yes, 

I was also surprised by the fact how well P-39 rolls. It's the opposite to what I've read from NACA evaluation of handling qualities: http://www.wwiiaircraftperformance.org/P-39/P-39D_Flying_Qualities.pdf

 

[ICDP]

These are also issues related to P-39 handling in BOX.  These are totally contradictory of available P-39 handling reports.

• Impossible to spin unless you absolutely force it.  Though I'm not sure a forced spin where you hold the controls to "simulate" a spin counts.
• When entered into a spin, the aircraft will eventually recover itself without pilot input.
• Roll rate better than a P-40.
• Gives plenty of stall buffet warning.

 

It looks like a P-39 I suppose.

Edited April 4, 2018 by ICDP
Reset joystick curves to default and it is now possible to spin the P-39 for me.

[56RAF_Roblex]

31 minutes ago, ICDP said:

Impossible to spin unless you absolutely force it.  Though I'm not sure a forced spin where you hold the controls to "simulate" a spin counts.

 

Not at all true.  I have managed to spin it a couple of times though it does not go into the difficult 'Fast-Slow' spin of the original which is unsurprising as it would take amazing modelling to simulate all the unique airflows needed for that to happen naturally.   It comes out of the spin with the normal 'nose down, opp rudder' which is fine because the official WW2 handbook for P-39 does say it recovers within one or two turns when done correctly.             Strangely I did once manage to get a Yak-1 into an inverted flat spin that I could not find a way out of!

[ICDP]

Can you tell me the circumstances you got a P-39 to spin?  I simply cannot get it to happen at all.

 

OK, I tried again but this time I returned my joystick curves to default.  Now the P-39 will spin quite easily but recovery is also easy.  I entered a spin at 5000m and attempted no recovery techniques, the aircraft recovered itself after a few thousand metres.

Edited April 4, 2018 by ICDP

[56RAF_Roblex]

4 hours ago, ICDP said:

Can you tell me the circumstances you got a P-39 to spin?  I simply cannot get it to happen at all.

 

OK, I tried again but this time I returned my joystick curves to default.  Now the P-39 will spin quite easily but recovery is also easy.  I entered a spin at 5000m and attempted no recovery techniques, the aircraft recovered itself after a few thousand metres.

 

 

As I said, the official pilots notes confirm that the P-39 does recover quickly if done correctly.  I think the reason it got a reputation for not being easy to get out of a spin is because the real thing needs a different recovery technique to most aircraft.  You had to apply rudder *with* the spin while holding the stick fully back until the spin slowed and only then would you apply opposite rudder and stick forward while applying opposite aileron.   The pilots notes also say that if you don't follow the correct procedure it will not recover at all.  If pilots were complaining  it would not exit a spin then either they were not taught correctly or possibly the instructors did not know how to recover at first either and it was only learned later when  the damage to its reputation was already done.      Yes the game version has a normal recovery technique.

 

You might find this video interesting, especially the demonstration of the gentle stall with no wing drop (29:00)  

 

Also try this 

 

 

Edited April 4, 2018 by 56RAF_Roblex

[ICDP]

You misunderstand, the sim version of the P-39 actually recovers without any pilot input.  This is contrary to all evidence you have presented.