Stability and Control characteristics of the Early Mark Spitfires

[Crumpp]

Just going thru the list in Morgan and Shacklady, I have counted 13 structural failures so far and I am only halfway thru the Mark I list.

It was serious enough that X4228 went to Farnborough on 24-8-40 to be used in testing to discover the cause of wing structure failures.

On a side note, X4181 on 17-840 was designated in 616 Squadron for "100 Octane Testing" and was shot down by a Bf-109 on 26-8-40.

Should have read this list earlier!!

[Crumpp]

17,000 Bonanza/Debonairs being made but isnt the Debonair a single fin aeroplane ?

The accident statistics include both types.

Again, the failures were notable enough for the RAF to send the plane to be tested to discover why the wings were failing in August of 1940.

Damn shame they did not have standards in place and that stability and control was such a new science at the time. Lives could have been saved.

[NZtyphoon]

Originally Posted by Crumpp

Just going thru the list in Morgan and Shacklady, I have counted 13 structural failures so far and I am only halfway thru the Mark I list.

It was serious enough that X4228 went to Farnborough on 24-8-40 to be used in testing to discover the cause of wing structure failures.

Serial Numbers please, and please scan and post the relevant pages. How many of them were elderly airframes in OTUs?

There was no Spitfire I serialed X4228

[Al Schlageter]

Originally Posted by NZtyphoon

Serial Numbers please, and please scan and post the relevant pages. How many of them were elderly airframes in OTUs?

There was no Spitfire I serialed X4228

I don't know where he got that serial number from. Notice it skips the numbers between 4189 and 4230.

X4009 X4038 30
X4051 X4070 20
X4101 X4110 10
X4159 X4188 30
X4231 X4280 50
X4317 X4356 40
X4381 X4390 10
X4409 X4428 20

X4471 X4505 35
X4538 X4562 25
X4585 X4624 40
X4641 X4685 45
X4708 X4722 15
X4765 X4789 25

X4815 X4859 45
X4896 X4945 50
X4988 X4997 10

[MiG-3U]

Originally Posted by Crumpp

Again, the failures were notable enough for the RAF to send the plane to be tested to discover why the wings were failing in August of 1940.
...

It was serious enough that X4228 went to Farnborough on 24-8-40 to be used in testing to discover the cause of wing structure failures.

Hm... so it was the X4268 which went to Farnborough for aileron testing Aug 40, the tests for wing failures were July 41.

Interesting interpretation

[NZtyphoon]

Originally Posted by MiG-3U

Hm... so it was the X4268 which went to Farnborough for aileron testing Aug 40, the tests for wing failures were July 41.

Interesting interpretation

This is clearer http://www.spitfires.ukf.net/p014.htm

X4268 Ia 1066 EA MIII FF 24-8-40 AMDP VA 24-8-40 RAE 9-40 aileron trials pilot J Quill. RAE 7-41 flight measurements of wing internal pressure for invest into struct fail of Spit wings. returned VAWD for continuation of trials.
ASTH for flaps mods. CRD AAEE 8-9-41 M45 install. Strengthened flaps tested as air brakes. 18-10-41 trials with thermostatically operated rad shutter ros VA 18-10-41 CRD DeH 23-11-41 39MU 18-2-42 3SGR 10-3-42 CF PRU engine failed wheels up landing nr Weeton Lancs CE 21-4-42 SOC 30-4-42

Opinions of an aerodynamicist:




No mention of longitudinal instability being a problem...
and an accident inspector:





(X4421 Ia 1138 EA MIII FF 12-9-40 8MU 13-9-40 66S 16-9-40 57OTU 21-10-40 steep dive from low cloud violent pull out high speed stall spun wing fail Pilot thrown clear but killed 15.15hrs crashed Northrop Flints 27-3-41 SOC cancel RAE 8-4-41 AST 13-5-41 rebuilt as Va M45 164S 29-4-42 FACE 18-8-42 (Rebuild suspect) )

One of the major causes - aileron instability caused by stretching cable - again no mention of longitudinal instability.

[robtek]

Isn't the instability the fact that the Spitfire tightens its turn by itself without further control input???
The pilot has to stabilize the plane by countersteering.
Like a rear wheel driven car in a power slide around a turn, working, but stable is different.

[bongodriver]

Originally Posted by robtek

Isn't the instability the fact that the Spitfire tightens its turn by itself without further control input???
The pilot has to stabilize the plane by countersteering.
Like a rear wheel driven car in a power slide around a turn, working, but stable is different.

It's not an effect that has ever got much mention, pilots are often quite candid about the quirks of aircraft they fly, and this thread is the first place I ever heard of it, it may have happened under certain conditions but I don't think it was a common feature of Spitfire handling.

[Crumpp]

No mention of longitudinal instability being a problem...
and an accident inspector:

Really? It was the second major problem he mentions out of the 68 structural failures.

Isn't the instability the fact that the Spitfire tightens its turn by itself without further control input???
The pilot has to stabilize the plane by countersteering.
Like a rear wheel driven car in a power slide around a turn, working, but stable is different.
Today 02:22 AM

Correct. You have to apply a push force when should be applying a pull force. It is called a force reversal.

So a small input becomes an ever increasing acceleration until arrested by a push force. It is a symptom of the instability.

This is a measured by the NACA and a function of the divergent oscillation stick free measured by the RAE.

At high speed, the aircraft acceleration can overcome the airframe's limits to destruction.

[Crumpp]

Still the "pro Spitfire faction" is trying to push the dispute to a black and white scenario and concentrate to steer the thread to sections where they believe to have valid counter-documentation.

The truth is always grey!

Undisputed should still be the sensitivity and lightness of the longitudal control of the Spitfire.

Also proven is the fact that the longitudal control isn't stable, as it increases the g-load without further pilot input.

Those things should be implemented in game.

If now a player pulls his joystick all the way back in a cruise speed turn, the plane should react accordingly as the resulting g-forces would be way above the structural limits.

The player should be forced to use a small input to initialisize the turn and the to almost neutralize the controls to hold that turn, as the pilots had to to in RL.

In a tightening turn there should be signals (i.e. vibrations) to indicate the beginning of the pre stall buffet, followed by shaking and the loss of energy and increasing turn radius when the turn is further tightened and the buffet is fully entered.

Further tighteneing the turn should lead to a flick-roll.

The disharmony between ailerons and elevators should also be there.

Imo that is a summary that should please any rational view on this thread.

Good Summary