A newbies impression of the 109 and spit

[NZtyphoon]

Originally Posted by 6S.Manu

You know that this matter can't be resolved right, do you?

not violent: there is no meter for the stall to be "violent/not violent".
unusual amount: is it possible to quantify the usual one? And usual compared to?
many flight conditions: which ones?
party stlled: again... no numbers.

If we want the real numbers we have to rent a spitfire, install on it all the modern testing stuff and run it.

I've never loved much the 109 while I've always hated the Oleg's Spitfire (but I love the real one since I was a kid): anyway I've never trusted the myth of the elliptical wings because of these planes fly against the physic laws compared to all the other ww2 planes.

The numbers and graphs start on page 25 of the NACA report on the Spitfire Va flight characteristics - which can be downloaded and viewed in its entirety, as can the NACA report on the Spitfire Va stall. Testing a real one would be interesting - Duxford anyone?

[Crumpp]

the possibility was that the Spitfire flown by NACA was slightly tail heavy.

Operating Notes Spitfire Mk IIa:



Operating Notes warning on the Longitudinal Instability:




NACA on the stall:



NACA on the Longitudinal Instability:



While CG certainly does effect stall onset and characteristics, I am certain the NACA was capable of doing a weight and balance. A new weight and balance would have been a requirement once the aircraft was rigged for testing.

They were very aware of the effect of CG position on stall characteristics too.

Both the stall characteristics and the longitudinal instability are included in the General Operating Notes for the Marks that did not recieve bob weights.

Actually I find this highlighted phrase (bold) more interesting in the quote of NZTyphoon:

Characteristics of the elevator control in accelerated Flight: (pages 8 & 9)

The elevator control was found to be powerful enough to develop either the maximum lift coefficient or the allowable load factor at any speed....(page 8 )

The Spitfire airplane had the unusual quality that allowed it to be flown in a partly stalled condition in accelerated flight without becoming laterally unstable. Violent buffeting occurred, but the control stick could be pulled relatively far back after the initial stall flow breakdown without causing loss of control. With the gun ports open, lateral instability in the form of a right rolll occurred, but not until an up-elevator deflection of 10° had been reached and unmistakeable warning in the form of buffeting had occurred. This subject is discussed more fully in reference 2.

The excellent stall warning made it easy for the pilots to rapidly approach maximum lift coefficient in a turn so long as the speed was low enough to avoid undesirably large accelerations at maximum lift coefficient.
The excellent stall warning possessed by the Spitfire was obtained at the expense of a high maximum lift coefficient. The maximum lift coefficient in accelerated flight was 1.21, while the average lift coefficient throughout a stalled turn was usually about 1.01 (9)

It says clearly that when riding the stall the margin was still big on pulling the stick.

I find the red phrase also interesting. Perhaps somebody with excellent understanding of flight mechanics can explain why large accelerations may be bad when flying at stall limit.

[Ze-Jamz]

Originally Posted by 41Sqn_Stormcrow

Actually I find this highlighted phrase (bold) more interesting in the quote of NZTyphoon:



It says clearly that when riding the stall the margin was still big on pulling the stick.

I find the red phrase also interesting. Perhaps somebody with excellent understanding of flight mechanics can explain why large accelerations may be bad when flying at stall limit.

Hmm, Im no expert, far from it but wouldnt/doesnt the AoA change when power is applied (torque) hence changing the flow over the wings?

Yes, to my understanding it would increase the speed (if longitudinal acceleration is considered) hence reduce AoA which hence should reduce stall.

With lateral acceleration increase (into the turn) the velocity vector should turn more but I do not understand how this could worsen the stall situation.

[bongodriver]

Originally Posted by Ze-Jamz

Hmm, Im no expert, far from it but wouldnt/doesnt the AoA change when power is applied (torque) hence changing the flow over the wings?

Sort of correct, mainly it's the AoA increase would put you over critical and you would get a departure, torque would just define which way you go into the resulting spin, the propwash wouldn't help much in this case.

The excellent stall warning made it easy for the pilots to rapidly approach maximum lift coefficient in a turn so long as the speed was low enough to avoid undesirably large accelerations at maximum lift coefficient.

My guess is that they do not address thrust increase otherwise they would have written it I think.

Reading more closely the phrase I come to think that they perhaps wanted to say "as long as g level remained low during maximum lift pulls" meaning that the absolut lift was low while providing maximum lift for that given speed.

[NZtyphoon]

Originally Posted by 41Sqn_Stormcrow

My guess is that they do not address thrust increase otherwise they would have written it I think.

Reading more closely the phrase I come to think that they perhaps wanted to say "as long as g level remained low during maximum lift pulls" meaning that the absolut lift was low while providing maximum lift for that given speed.

The report includes a series of graphs recording the information; incidentally

Reference 1. REQUIREMENTS FOR SATISFACTORY FLYING QUALITIES
OF AIRPLANES can be found here

[Glider]

I admit to wondering what all the fuss is about. The vast majority of my flying experience has been in gliders so what I say comes with that caviet.

Any high speed stall is an exciting event even in a glider. By definition things happen quickly and often violently, so no suprise there.

Where the pilots notes warn about rough conditions causing the pilot to make control movements that can impact flight, its common sense and often happens. It could be that my experience is different here as what a powered plane calls turbulance is what we call potential lift and have more experience flying in those conditions. This warning would apply to any small aircraft, be it a Spitfire, 109, Piper Cub or glider.

Flying on the edge of a stall using the stall warning to stay close to the maximum performance is again a good thing, glider pilots often fly on the edge and in one case when I lost my instruments whle thermalling in a cloud with driving rain, had a good deal to do with my safe exit.
Edit - had my glider had automatic front edge slats like the 109, I may well have had to bail out, never thought of that before.


A violent spin if you push past the boundary is again nothing to worry about, it happens and you are trained not to go past the edge. I have seen international standard pilots make this mistake and spin out of a stack. You soon recognise the warning signs.

A couple of general observations,
a) the best fighters are by design borderline unstable.
b) Nearly all the reports I have seen from German pilots who flew captured Spifires said that they were easier to fly than the 109. This again supported by the Jugoslav airforce who had both Hurricanes and 109E's and used the Hurricane as a lead in to the 109 because of accidents. The RAF didn't use Hurricanes as a lead in to the Spitfire.