Stability and Control characteristics of the Early Mark Spitfires

[Crumpp]

When are we getting the 109 thread?

You guys want to do the Bf-109 next?

I was going to do the Hurricane next.

[Crumpp]

The anti-Spitfire, bad longitudinal instability faction can only see a cloudy, murky-grey, glass half empty scenario where there is no clear evidence that longitudinal instability actually caused in flight structural failure and they don't like black and white evidence being posted to show how doubtful their case is.

But it is not that way.

First, the anti-Spitfire faction exist's only in your mind.

Second, anybody who knows stability and control can read the article to see the characteristics clearly.

The gentleman who was interviewed for the article points out the fact they did not have a good understanding of stability and control engineering at the time.

The article is most interesting because it shows the thought process of the day and not for its engineering conclusions.

You however, take those engineering conclusions as proof. By that thinking, we should be doing meta-center calculations to prove the airplane was stable!!

[NZtyphoon]

Originally Posted by Crumpp

But it is not that way.

First, the anti-Spitfire faction exist's only in your mind.

That's reassuring - you all can stop the "pro-Spitfire faction" nonsense then.

Originally Posted by Crumpp

Second, anybody who knows stability and control can read the article to see the characteristics clearly.

You mean poor longitudinal stability? By all means point it out to the ignoramus' surrounding you.

Originally Posted by Crumpp

The gentleman who was interviewed for the article points out the fact they did not have a good understanding of stability and control engineering at the time.

What he does point out is that it was extremely difficult visualising the type of combat likely to be faced in a future war - he does not point "out the fact they did not have a good understanding of stability and control engineering at the time."

Jeffrey Quill Supermarine Chief test Pilot:




The bob weights introduced in 1942:





No stability problems Mk I & II, although borderline; Spitfire Vs incorrectly loaded at a squadron level in 1942, so bob-weights fitted in a "crash" (sic!) program before elevators modified with a larger mass balance.

[bongodriver]

Originally Posted by Crumpp

You guys want to do the Bf-109 next?

I was going to do the Hurricane next.

Why didn't you start threads concurrently?

[Glider]

Crump

Before you start everything I would much prefer it if you used a more complete and modern set of standards for the calculations.

The most recent ones that I had any dealings with were

MIL - STD - 1797A

The fundamental problem that I believe you have, is that something is either stable or unstable. These standards give levels of accaptable stability for different types of combat aircraft. For instance you would expect what is acceptable for a C17 to differ from an F15 or you end up with an F15 which is a sitting duck or a lot of airsick troops in the C17.

I last used these in the late 1980's and there is a better than average chance that they may have changed in that time, so you may want to look into it.

However to carry on with the black and white process that you have is foolish and totally out of kilter with the real world. In the real world its a mixture of theory your preferred approach, how they actually feel to fly which is my approach, plus what are they desinged to do. These are normally combined and we used to refer to the flying qualities.

If I go back to the three gliders I mentioned an age ago.
The Twin Astir was very heavy and as far as aerobatics was only really good in the vertical, but it was excellent for training people to go cross country as it had less need to thermal but was fast.
The K21 was a much better all round glider good at most aerobatics and for training. However it was almost impossible to spin, a major problem in a trainer. So much so we use an old K13 for Spin Training which I loved to fly. The K21 was also good for training all types of flying thermalling and cross country
The Fox was a dedicated aerobatic machine. You certainly didn't want to go cross country or thermal but if you wanted to learn the fine points of aerobatics, this was the machine to use. Excellent roll rate for a glider and very precise in the control.

All design is a balance and as I write this the BOB Lancaster and a Spit have just flown very low over my house at about 5-700 ft

Back to the topic the term we use is the flying quality of the machine, which has to take in the task in mind, how it feels and the theory. These standards cover this combination
The