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gx007

Spitfire stall and glide behavior

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Hey all,

 

Thanks devs for the spit. I've been really enjoying it.

 

I tested the spit for its stall speed and was surprised by my findings. Can someone verify it's behavior is correct please.

 

Here are my findings:

 

  • Used Stalingrad winter map, air start at 2000m, Merlin 46 and 45 engines. 50% fuel. 0% throttle, rpm, mixture.
  • It took a long time (sorry didn't have my timer out) for speed reduction. It hoovered around 80 mph with no threat of stall.
  • Cut the engine and it stayed aloft for several seconds before showing any sign of stall. The prop kept spinning. Shouldn't it have stopped?
  • Dead-stick glided (1000m altitude) to the nearest airbase about a mile away. No sense of dropping like a rock. 

 

thanks

kind regards

gx

 

 

post-10129-0-50617200-1499625037_thumb.png

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I find the yak1b glides very well too however if your engine is busy and the prop stops (aka lots of drag) you will sink like a stone :)

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With a wing loading of just 133,5 kg/m2 when fully loaded and less than 110 kg/m2 when nearly empty as well as a wing designed for low lift induced drag, it makes sense, that the Spit would be in a whole different league than all the other aircraft in BoX when it comes to gliding. The lower the airspeed the less form drag matters and the more lift induced drag matters.

 

I think the Spit has the lowest landing speed of any aircraft in the game save for maybe the Ju 52. 

Edited by Finkeren

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About Spitfire stall.

Spitfire is keep controllability in the stall.

NACA report from Spitfireperformance: http://www.wwiiaircr...-V-Stalling.pdf

Conclusion from this report:

 

 

 

post-237-0-27163800-1499163227.jpg

 

 

In general, from flight records from this report: Spitfire has unusual stall characteristics, motion beyound the stall is not violent and airplane still have lateral controllability. If you hold stick in position, required to start stall, airplane does not have a strong tendence to roll. If you continue pull stick, you may control aircraft by rudder and elevator beyound the stall.

And from british flight tests (http://www.spitfireperformance.com/aa873.html):

"At about 90 m.p.h. A.S.I. a considerable amount of buffeting around the hood commences. The A.S.I. can be reduced to 81 m.p.h. but at this speed sharp fore and aft pitching occurs together with increase of buffeting. This sharp fore and aft pitch prevents the control column from being held fully aft.
In general the stall of the aeroplane is not clearly defined.
There were no signs of either wing tending to drop. The elevator is moderately heavy though effectiveness has fallen off considerably."

 

 

  • Upvote 4

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Just to add in case anyone brings this up: the Spitfire V Pilot's notes give a clean stall speed at 73 mph IAS - a lot lower than the speed you will read in game.  This does not mean that the FM is wrong, it means that in game instruments do include the errors that RL instruments had to deal with, which are very large at low speeds and high angles of attack.  The game stall speeds compare very closely with the tests using more sophisticated measuring techniques done by the RAE.

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the Spitfire V Pilot's notes give a clean stall speed at 73 mph IAS - a lot lower than the speed you will read in game

 

In this report http://www.spitfirep....com/aa873.html stall speed - 81...90 m.p.h. with flaps and undercarriage up and 71 m.p.h. with flaps down. And, dont forget, that airspeed indicator has position error. -4 m.p.h. at low speed, that statued in flight manual. So, real stall speeds near- 85...94 and 75 m.p.h. (flaps up/down).

And, if the stall speed were 73 miles per hour from pilot manual, then lift coefficient Cl should have been about 2.0 (for 3000kg Spitfire). This is fantastic value. I think, that is theoretical number, recalculates from early Spitfire. In the report above there is an example of such a recalculation with similar numbers.

  • Upvote 6

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also keep in mind that as the airspeed drops and the AoA of Pitot tube increases and airspeed readings become even more innacurate

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also keep in mind that as the airspeed drops and the AoA of Pitot tube increases and airspeed readings become even more innacurate

For such readings, special installations were used that are less affected by AoA etc. The values are fairly accurate.

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In this report http://www.spitfirep....com/aa873.html stall speed - 81...90 m.p.h. with flaps and undercarriage up and 71 m.p.h. with flaps down. And, dont forget, that airspeed indicator has position error. -4 m.p.h. at low speed, that statued in flight manual. So, real stall speeds near- 85...94 and 75 m.p.h. (flaps up/down).

And, if the stall speed were 73 miles per hour from pilot manual, then lift coefficient Cl should have been about 2.0 (for 3000kg Spitfire). This is fantastic value. I think, that is theoretical number, recalculates from early Spitfire. In the report above there is an example of such a recalculation with similar numbers.

 

Yes I know Gavrick - that is why I posted.... we had a similar discussion about the P-40 where the manual stall speed and the game stall speeds are out of whack. My point there, as here, was that you have got it right given the evidence as a whole, not that you have got it wrong!

 

-4 is for 100-140 mph btw in the pilot's notes: the RAE tests with a trailing pitot the error at stall speed is much higher than 4 mph: again, further evidence that you have got it right.

 

TBH the only thing I am still a bit puzzled about is the pitch up when lowering flaps/gear - pilot's notes say pitch down. Your explanation about stability was way above my level, however, so I am happy to take it as it is. :)

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Thank you for your responses everyone.

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