Stability and Control characteristics of the Early Mark Spitfires

[MiG-3U]

Originally Posted by CaptainDoggles

You know Crumpp's right about expressing CG as a percentage of MAC. The Datum point doesn't have to be in the same spot for the results to be valid. That's why it's called a datum point.

There is only one accurate reference point for the CoG in the NACA report, the distance of the CoG from the leading edge at the wing root and that is given as 31.4". NACA admits that their measurements for MAC maybe in error and we can easily see that there is error because in the RM2535 the 34% CoG location at the RAE measured MAC is also given same way as distance from the leading edge at the wing root and the value is 2.638' which is 31.656". Even with these values only we can estimate that the real CoG location was about 33.7% at the MAC given by RAE instead 31.4% claimed by NACA (and NACA admited that their value might be wrong).

As we know accurate reference point at the wing root and dimensions for MAC used by RAE and A&AEE and datum line, we can also easily calculate these.

Lenght of the MAC measured by RAE and A&AEE is 78.54" (or 6,54') and position 31.4" behind leading edge at root is 26.4476" at MAC and that means that CoG was at position 33.6741% in the NACA tests using RAE and A&AEE dimensions.

However, British documentation gives CoG values usually as distance from the datum line so we need to make NACA CoG location comparable with these. And that is easy because we know that the datum line is 18.65" behind leading edge at the MAC:

26.4476" - 18.65" = 7.7976"

And this value, 7.8" aft datum line, is comparable with the other sources like A&AEE and RAE tests and loading instructions.

Over and out.

[TomcatViP]

Originally Posted by Fenrir

These characteristics you describe are NOT representative of all Spitfires. Therefore they should NOT be in game. Read again my post on stability. It affected *some* - and it seems I need to remind some people here that does not mean all - Mk V aircraft. A Mk V is NOT a Mk I, or Mk II.

All I can suggest is that you guys go away and read the books I've read, go further make even more research and come back and make an informed opinion then. Please for pity's sake do not take the one single example of an agenda driven poster as gospel.

The NACA test discovered what they discovered - I can't argue with their findings, FOR ONE PARTICULAR AIRCRAFT. However I cannot agree that these are representative of the breed. And as for relevance, well, I've said it already. A Mk V is not a Mk I.

Did RAE and NACA test the same aircraft ? Because so far we can see they draw the same conclusions.

And oh nasty they are, they even gave some recommendations in the handbook. I guess that they wanted to wage a war 70 years latter on a dark corner of the internet

[robtek]

The "agenda driven" shoe fits some feet here, i believe.

[Fenrir]

Originally Posted by TomcatViP

Did RAE and NACA test the same aircraft ? Because so far we can see they draw the same conclusions.

And oh nasty they are, they even gave some recommendations in the handbook. I guess that they wanted to wage a war 70 years latter on a dark corner of the internet

Can you direct me to the RAE test please? I've not read it.

Tomcat, I'm not interested in getting into a slanging match, but I'm finding your tone a little condescending. Can we both agree to keep our future posts a little less aggressive? I'm just trying to present the whole picture as I understand it, without fixating on one source.

Likewise Robtek - I have an agenda, true; I'd like to see every aircraft represented as accurately as possible with the widest possible references to minimise the possibility of error. I just happen to know a great deal about a few aeroplanes (P-38 and P-51 amongst them) with the Spitfire being high on the list. My reference library is not exactly small though by no means complete, and it has been thoroughly absorbed over 20 years. So, you'll exuse me for calling someone out if I think they are presenting data that is either unrepresentative, of poor relevance or inaccurate, on a subject i know a great deal - but not all, admittedly - about.

I'm not after a super plane in game; I simply want both sides to have the pros & cons that the prototypical aircraft had. No more, no less.

[lane]

Originally Posted by Fenrir

Can you direct me to the RAE test please? I've not read it.

Tomcat, I'm not interested in getting into a slanging match, but I'm finding your tone a little condescending. Can we both agree to keep our future posts a little less aggressive? I'm just trying to present the whole picture as I understand it, without fixating on one source.

Hi Fenrir,

Here's some of what I've found that might be of interest:

NACA A.C.R., Sept 1942: Measurments of the Flying Qualities of a Supermarine Spitfire VA Airplane
NACA A.C.R., Sept 1942: Stalling Characteristics of the Supermarine Spitfire VA Airplane





Perhaps also of interest: R & M No. 2535 High-speed Wind-tunnel Tests on Models of Four Single-engined Fighters (Spitfire, Spiteful, Attacker and Mustang)

Fwiw from A. & A.E.E. Spitfire I report 15 June 1939: