Stability and Control characteristics of the Early Mark Spitfires

[ATAG_Dutch]

Originally Posted by TomcatViP

Regarding the Cessna, if you really push and turn the yoke My memory tell me that the 172 is quite manoeuvrable. I won't hve had a dogfight with a 29 but still you feel secure in mountainous terrains.

Yes, but release the yoke and the Cessna returns to normal flight due to its stability.

[taildraggernut]

Originally Posted by ATAG_Dutch

Yes, but release the yoke and the Cessna returns to normal flight due to its stability.

exactly and you get very tired very quickly wrestling a stable aircraft around the sky.

Two of the most manoeuvrable fighters today are perfectly stables: Mig29 and Su27.

the 29 is practically obsolete, the 29's inherent stability is why it no longer competes against modern fighters, and the 27 is fly-by-wire.

I don't see why a pilot would want an unstable aircraft especially in pitch when you have to do lengthy flight in clouds, bad weather or simply T.O at dusk

mainly because it gives the edge in a dogfight because of the increased maneverability, I'm fairly sure flying in cloud is not a high priority in fighter design.

[TomcatViP]

Again You are mixing instability and relaxed stability.

instability would make the plane depart itself from its velocity vector

relaxed stability is implemented in the design but ctrl the plane trough a computer. And there is a raison to that.

Exemple :

Stable or FBW stable F16 Rookie pilot: 400Kts, pull 6G -> Black out -> the plane unload by itself. Pilot woke up 10 sec after safely

Taildraggernut design instable "NutShark Uber Killer 2121" aircraft with Tomcat pilot : 400kts, pull 6G, Black out -> the plane continue to tighten the turn untill what remain of Tomcat'brain is crushed. Pilot CTG 10 sec latter.

Note:
- The 27 does not have FBW implemented. Only latter vers have pitch ctrll.
- Good luck trying to teach NATO or US fighters pilots that the 29 is obsolete. You might have the same kill rate ratio as them in BFM

[taildraggernut]

Originally Posted by TomcatViP

Again You are mixing instability and relaxed stability.

instability would make the plane depart itself from its velocity vector

relaxed stability is implemented in the design but ctrl the plane trough a computer. And there is a raison to that.

Exemple :

Stable or FBW stable F16 Rookie pilot: 400Kts, pull 6G -> Black out -> the plane unload by itself. Pilot woke up 10 sec after after

Taildraggernut design instable NutShark Uber Killer 2121 aircraft with Tomcat pilot : 400kts, pull 6G, Black out -> the plane continue to tighten the turn untill what remain of Tomcat'brain is crushed. Pilot CTG 10 sec latter.

Note:
- The 27 does not have FBW implemented. Only latter vers have pitch ctrll.
- Good luck trying to each NATO or US fighters pilots that the 29 is obsolete. You might have the same kill rate ratio as them in closed dogfight

I'm not mixing anything.....but with a statement like yours I think you are mixing some volatile chemicals right now.

p.s. the Su-27 had a 'pitch only' fly by wire

http://www.milavia.net/aircraft/su-27/su-27.htm

[TomcatViP]

Originally Posted by taildraggernut

I'm not mixing anything.....but with a statement like yours I think you are mixing some volatile chemicals right now.

Rgr that TDN, hve fun

[Crumpp]

We should note that words like "instability" can have a narrow technical meaning that is rather different from their normal everyday meaning. Crumpp would have avoided a lot of confusion, much of it his own, if he had made this distinction clear from the beginning.

Really guy??

Obviously you have not read much of the documentation in this thread or seen the Cm over Cl plots.

[Crumpp]

the relationship between stability and maneuverability

Feel free to point out where the manual states a fighter should be unstable.

Thank you.

[ATAG_Dutch]

OK, now you're back please answer my question, this is the third time.

What is the purpose of this thread, and what are you trying to prove?

Edit: Sheesh, the bloke mustn't read very much. He's gone again.

[taildraggernut]

Originally Posted by Crumpp

Feel free to point out where the manual states a fighter should be unstable.

Thank you.

Ok, take time to very very carefully understand the point, it clearly shows how slight instability is beneficial for maneuverability....a desireable quality in a dogfighter yes? at no point have I said a fighter 'needs' to be unstable, if it is a ground pounder then stability is probably a desireable quality, if it is an interceptor then it is also probably good to be stable, but a pure air defence dogfighter would benefit greatly from being able to outmanouver an opponent.

Youre welcome.

[6S.Manu]

Originally Posted by Crumpp

Feel free to point out where the manual states a fighter should be unstable.

I feel "standards" can be misleading. How should a fighter be?

Standards are used to hold down the aircraft characteristics with an "ideal one" in mind.

But as Tomcat says "It's a matter of philosophy from the manufacturer and the air forces using it."

So the longitudinal instability of an airplane can be required by some airforces (more or less instability) and totally avoided by other.

One can produce an highly dangerous airplane that is really effective (look at the Tempest) while other can design a safer plane that influences greatly the pilot's range of manoeuvre.

In my opionion this thread demostrate that Spitfire had some characterics who actually were dangerous if the pilot was not experienced... the ability to reach a great amount AoA in so little time (given the low stick forces) CAN BE dangerous if the pilot is not really well trained. Above all if the manoeuvres were made by sharp actions on the stick. The pre-stall warning could easily alerts the pilot if he was entering in the turn smoothly, but since it raised only a pair of mph over the stall speed I really don't think that it could be recognizable during a sharp turn that could easily end in a violent stall.

Because of this there were pilots afraid to turn tightly.

It's like the drifting capability of a car: some capable pilots can recognize the limit and containing a loose car from spinning but an average pilot will not always succeed in it and will find himself with the car pointed at the wrong way.

Then we can talk of "aiming" in a longitudinal unstable aircraft...