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-   -   Stability and Control characteristics of the Early Mark Spitfires (http://forum.fulqrumpublishing.com/showthread.php?t=33245)

TomcatViP 07-28-2012 04:15 PM

Ehhh, guys you should calm up.

There was a lot of planes designed in the mid 30's that had pitch instability.

I won't submit you to an aerodynamics exam but Britain, it's a fact, was lagging behind the leading countries in that field of knowledge that were Germany and USA. USA was among the leading country in part because Karman went to work at the NACA in 35/36 (read his book - it's a fascinating tale of time of the great pioneer).

Anyway this is why many british design were too rounded or to thin or somewhat bulky. Not individualy (there was many talented scientist and aerodynamist) but as an institution, they did not master the viscous conditions as much as the leading nations. What was the key to understand plainly aerodynamics.

France had the same amount of knowledge as UK at the time. This is why most of the French design were seen as low performers as the testing didn't meet the expectations of the design teams (hence lower strain on HP demands, higher thickness ratio, lower wing surfaces etc... - One good example of that is the Curtiss H-75 (P-36) from US that was designed before 1935).

Russian did realize that and after the outbreak of WWII a high priority was given again to fundamental research and testing (the TSAGI) up to the point that the late Russian design during the war were above performer (at least in their prototype form). By the way, a little note to the guy in this forum that put Britain at the forefront of aeronautics knowledge when a bit of search will tell you that all this started with Joukowsky, a Russian Mathematician (http://en.wikipedia.org/wiki/Joukowsky_transform)

Before you start repeating your tirade about how British were at the for front of the sciences of aerodynamics etc... Let me tell you this: The father of the Buccaner, leading engineer for years at Blackburnand then BAe (started his carreer at Gloster if I do remind well) explains all this in his book. It tell us the fascinating story of how the Brits test facility were relaying on inappropriate methods (at least not accurate) to simulate airflows in the 40's.

Oh, and by the way, he was also on the board of the British team that worked teh design of the SuperUberModern EF2000billions£. That tell you a lot about how much this design is ready to plink the 21'st century threats - Bah it's another story!

I don't have the name of course. But in regard to your disgusting way of smoking every thread, irrespective prose, and what can be called blatant lying I won't do a single search.

Easy to found : Buccaneer story published in the 80's - small format - no images just text- Cover red, white and blue of course !

Glider 07-28-2012 04:59 PM

I would like to know the name of the book if possible, the Bucaneer was one of the planes I was trained on and had a huge respect for it. Well ahead of its time and in many ways better than the Tornado that 'replaced' it, in my totally unbiased opinion.

As for the theory that the USA were so far ahead there are a few problems with that.

In 1938 the period when the Hurricane, Me109 and SPitfire were entering service the USA had the P35 and P36. Most wouuld consider the P36 to be the better machine but the P35 won the Contest for the USAAF.
The P43 entered service in 1940 when the RAF were getting the Spit II and the German Airforce were close to the 109F. The P40 was always behind the curve.

In bombers its a similar story. The Luftwaffe and RAF had Wellington, He111, Ju88, Do 17 Stuka, Hampden, even the Whitley. The USA had the B18, the Boston was on the way but not until 1940 which was too late and this had some issues. It wasn't all great, the Battle is an obvious example but the european countries had options.

I find it hard to see where this significant advantage the USA had in theory was being applied.

In transport aircaft the USA had a clear lead and naval aircraft.

The USA may have had theoretical advantages but its wrong to overstate it. Its also worth remembering that production of aircraft such as the Fw190 and Mosquito were close behind

TomcatViP 07-29-2012 10:02 AM

Quote:

Originally Posted by Glider (Post 448934)
I would like to know the name of the book if possible, the Bucaneer was one of the planes I was trained on and had a huge respect for it. Well ahead of its time and in many ways better than the Tornado that 'replaced' it, in my totally unbiased opinion.

Will do my best Glider but can't promise anything.

Edit : Here it is ! Sisi it include the Bucc full story ;) The book tittle was just made sexier with the added types for the neophytes ;)

Buy
http://www.amazon.co.uk/exec/obidos/...underandlightn

Review
http://www.flyingbooks.co.uk/acatalo...rofighter.html

NZtyphoon 07-29-2012 10:43 AM

Quote:

Originally Posted by IvanK (Post 448542)
So then Mr Crumpp exactly what is wrong stability wise with the IL2 CLOD Spitfire MI I or II Ver 1.06.17582+Hot Fix

According to Crumpp the Spitfire was dangerous:

http://forum.1cpublishing.eu/showpos...&postcount=245

"The solution for the unacceptable and dangerous longitudinal instability of the Spitfire was bob-weights." These were added not because the NACA made a mistake in some half baked theory on weight and balance calculations. They were added by the RAE to correct a serious stability and control issue with the design."

(No they weren't, they were added by Supermarine to control a truly dangerous instability problem caused by poor loading at squadron level, but we can let Crumpp away with his poor grasp of history - he's only an engineer. :rolleyes:)

One solution to the "dangerous" instability exhibited by the Spitfire would be for the IL2 developers to add bob-weights - ASAP!

Holtzauge 07-29-2012 12:04 PM

While no one can argue that the NACA was not at the forefront of aeronautics in the mid 1930's, the bashing of British aeronautics and the raising US dito as a beacon of enlightenment seems a bit simplistic given that the US fielded a TRANSPORT aircraft at this time that was actually longitudionaly UNSTABLE in some flight conditions: The Douglas DC-3 was with normal rated power and also under approach conditions statically UNSTABLE. See NACA TN 3088 (Can be downloaded from the NASA NTRS server) page 31 figure 5. Now compare that to figure 9 page 27 of NACA L-334: The Spitfire FIGHTER shows a NEUTRAL/SLIGHT POSITIVE stability and a better elevator force/speed curve than the UNSTABLE DC-3 TRANSPORT.

While both aircraft undoubtedly would have benefited by a larger margin of stability from a control perspective (logically larger for the DC-3 and smaller for the Spitfire) it is by far easier to overlook NEUTRAL stability in a FIGHTER rather than actual INSTABILITY in a TRANSPORT. Also note that the INSTABILITY inherent in the DC-3 did not stop it from becoming a legendary an popular aircraft held in high esteem by the pilots who actually FLEW them so I think one should be careful before making assertions that the NEUTRAL/SLIGHT POSITIVE stability exhibited by the Spitfire was a serious problem. Another thing to consider is that neutral stability in general means less drag and therefore higher performance and that the pilot can generally more easily transition between high and low speed conditions without retrimming or excessive control forces, both of which are valuable traits in a FIGHTER design.

Finally, I can only second the call to present what is actually wrong with the current Spitfire modeling in CoD: As the saying goes, if it ain't broke then don't fix it. While I readily admit to not having read through the entire 59 pages with a loupe the formulation of the actual problem and what needs to be fixed escapes me.

Glider 07-29-2012 02:56 PM

Quote:

Originally Posted by TomcatViP (Post 449001)
Will do my best Glider but can't promise anything.

Edit : Here it is ! Sisi it include the Bucc full story ;) The book tittle was just made sexier with the added types for the neophytes ;)

Buy
http://www.amazon.co.uk/exec/obidos/...underandlightn

Review
http://www.flyingbooks.co.uk/acatalo...rofighter.html

Thanks for that

Crumpp 07-29-2012 04:08 PM

Quote:

If you want to sell instability to me, or anyone else who's got a good understanding of the matter, you'll need to explain how both of the above gradients can be positive in an unstable aircraft and how it was possible to fly the smooth stick fixed turns as shown in figures 17 and 18.
:rolleyes:

http://img827.imageshack.us/img827/8...res17and18.jpg

Quote:

or anyone else who's got a good understanding of the matter,
Your good understanding? Is that with the long period oscillation's your claimed, the slopes of the curves, the difference between stick fixed, stick free, dynamic and static?? I am confused as to where your good understanding is demonstrated.

Holtzauge 07-29-2012 05:35 PM

OK, I see the problem now: What Crumpp fails to understand is that while the actual stick movement is small, figures 17 and 18 show that the pilot uses between 10-20 lb of pull to HOLD the turn. If one looks at the force histogram its apparent that a relatively constant pull force is needed to keep the plane in the turn. So no increased pull force no increased load factor. Wherein lies the big problem? What would be troublesome would be if there was a need to apply a push force or substantial unloading in order not to tighten up the turn once it had been initiated. However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.

Maybe this is also why we on the one hand have numerous accounts from pilots who actually flew the Spitfire and appreciated it and on the other have a private pilot armchair expert who is of a different opinion based on a myopic and selective interpretation of data.

Crumpp 07-29-2012 05:47 PM

Quote:

OK, I see the problem now: What Crumpp fails to understand is that while the actual stick movement is small, figures 17 and 18 show that the pilot uses between 10-20 lb of pull to HOLD the turn. If one looks at the force histogram its apparent that that a relatively constant pull force is needed to keep the plane in the turn. So no pull force no increased load factor. Wherein lies the big problem? What would be troublesome would be if there was a need to apply a push force in order not to tigthen up the turn once it had been initiated. However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.

Maybe this is also why we on the one hand have numerous accounts from pilots who actually flew the Spitfire and appreciated it and on the other have a private pilot armchair expert who is of a different opinion based on a myopic and selective interpretation of data.
Quote:

However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.
:rolleyes:

Spitfire Mk I Operating Notes, July 1940:

http://img109.imageshack.us/img109/7976/page10jv.jpg

http://img26.imageshack.us/img26/2599/page12dh.jpg

http://img542.imageshack.us/img542/9202/page13o.jpg

http://img607.imageshack.us/img607/2471/page15j.jpg

http://img651.imageshack.us/img651/2456/page16lu.jpg

By all means continue Holtzauge.

Let's stick to what is definable and measureable, as this is my thread.

Holtzauge 07-29-2012 06:53 PM

Quote:

Originally Posted by Crumpp

Let's stick to what is definable and measureable, as this is my thread.

Yes, let's stick to that: To begin with follow your own advice: What you posted above is as has now been pointed out numerous times some general advice to the pilot on handling characteristics and hardly qualifies to your own strict limitations to what is definable and measurable so you can remove them from "your" thread.

Now what is pertinent and admissible according to your own definition above are figures 17 and 18 so please enlighten us with how these support your case as opposed to mine and JtD's interpretation above.


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