Stability and Control characteristics of the Early Mark Spitfires

[ATAG_Dutch]

So with a full tank, trimmed for level flight, pulling back on the stick then releasing to neutral would return the aircraft to level flight.

With a half full tank in the same conditions, pulling back on the stick would need a push on the stick to return to normal flight, and a bigger push when the tank is near empty.

That's my simplistic understanding of longitudinal stability or not as the case may be.

All modern military aircraft are designed with inherent instability which requires a computer to control. Instability is necessary for manoeuvrability.

I totally fail to see the point in this thread, other than to ask the devs to model a changing CofG and longitudinal stability according to fuel load. Is that the point?

[CaptainDoggles]

Originally Posted by ATAG_Dutch

I totally fail to see the point in this thread, other than to ask the devs to model a changing CofG and longitudinal stability according to fuel load. Is that the point?

Here's a simple example from the game: Right now, to hold a turn in the spit you have to hold the stick back a significant amount.

In reality, after initiating the turn I believe it was necessary to relax your pressure on the stick (move it closer to center). Otherwise, the aircraft could tighten its turn, and if you are above corner speed that means it would be easy to inadvertently exceed the G limits and damage the airframe.

There's a quote I remember reading from a pilot who said he actually had to push the stick almost all the way forward to hold a turn, because the aircraft kept wanting to tighten up.

--

I also think that the very light stick forces and (lack of) control harmonization should be modeled.

[ATAG_Dutch]

Originally Posted by CaptainDoggles

There's a quote I remember reading from a pilot who said he actually had to push the stick almost all the way forward to hold a turn, because the aircraft kept wanting to tighten up.

I too have read such anecdotes, however the aircraft had to be returned to the factory for a new monocoque, as for some reason a batch of Spits had been produced out of shape.

Dangerous to trust pilot's anecdotes, as we keep being told.

Edit: Plus you'd be unconscious well before you endangered the airframe.

[winny]

I have another question, the RAE refer to the bf-109 as being " too stable for a fighter".

So is instability a good or bad thing?

[Al Schlageter]

Originally Posted by winny

I have another question, the RAE refer to the bf-109 as being " too stable for a fighter".

So is instability a good or bad thing?

It depends if one is BLUE or RED.

[CaptainDoggles]

Originally Posted by winny

I have another question, the RAE refer to the bf-109 as being " too stable for a fighter".

So is instability a good or bad thing?

I've read that quote, but Mike Williams seems to have sort of picked it out without including a lot of context from the original source, so it's hard to know exactly what they were referring to.

Here's the quote for people unfamiliar:

Longitudinally the aeroplane is too stable for a fighter. There is a large change of directional trim with speed. No rudder trimmer is fitted; lack of this is severely felt at high speeds, and limits a pilot's ability to turn left when diving.

Now, the way I interpret it is that they're referring to the trim problem. I could be wrong. There could be a truncated sentence or two preceding the quote that makes it more clear, but that's how I interpret it.

Edit: I think in this case that they're correct. You don't want the pilot's attention on trimming the aircraft every five seconds; you want the pilot's attention devoted to situational awareness.

[winny]

Originally Posted by CaptainDoggles

I've read that quote, but Mike Williams seems to have sort of picked it out without including a lot of context from the original source, so it's hard to know exactly what they were referring to.

For your reference, the quote, in context.



Apologies for the quality, it's an iPad screen grab.

[lane]

Originally Posted by winny

For your reference, the quote, in context.

Thanks for the context winny! Here is some more "context":

[ACE-OF-ACES]

Originally Posted by lane

Longitudinally the aeroplane is too stable for a fighter

Bingo!

Just as I was saying.. Fighters, than and now, intentionally design an alittle instability to make them more maneuverable!

So I can understand how some modern civ pilots..

Who are already blinded by their agenda

Could fool themselves into thinking a fighter that does not have the same stability attributes of their putt-putt cessna is a failure.

[winny]

For anyone who would like to read the full RAE evaluation of the 109 it's here in PDF.

It's 14 Mb and should open in your browser, you can then save it if you wish.