Crumpp

Yes it is well within the CG range. But it is NOT the wartime AFT CG limit is it? The wartime AFT CG limit for a NORMAL Spitfire Mk IX without tanks is 9in aft of datum!! But as you nicely point out proving my point, we can see why most modern Spitfire Mk IX aft CG limit is even more restricted can't we? You so nicely proved to yourself exactly what I was trying to show you pages back when I posted so many Spitfire Mk IX Type Certificates! If you had just taken the few minutes to read the details like I asked we could have ended this then. :thumbup:

Is not the Aft CG limit for the Mk IX. It is just telling you where it will be with the rear fuselage tanks empty of fuel. (-7.4-21.89)/85 = 34.45% MAC 31.4%MAC - 34.45%MAC = 3.05% AFT of the NACA tested CoG location.

My math had nothing to do with that footnote and does not solve for EWCG. You are turning in circles chasing your tail.

Run the math....Run the math... You are lost in the sauce, bongo. I solved for the LEMAC the NACA was using and compared their datum point to the RAE/Supermarine datum point so I could correct evaluate the CG locations.

Yeah, that is one of those time building jobs nobody will pay you for to do it. I flew a WACO giving tours to build time too. Did not get a living wage either.

Here:

I already showed the conversion and the proof. Without the rear tanks, the Spitfire Mk IX Aft Cg limit is 9 inches aft of datum. (-9-21.89)/85 = .3634 * 100 = 36.3% http://forums.eagle.ru/showpost.php?p=2527236&postcount=113 If you need a Spitfire Mk IX weight and balance sheet I can post that for you too.

The entire purpose of permanent ballast is to RESTORE the Empty Weight CG when a design has been altered. End of Story. Once more ballasting does not effect the CG limits nor does it effect the the fact that at any CG location the stability margin of the Mk IX equals the stability margin of the NACA Spitfire Mk V..... The stability characteristics are the same given the same stability margin. End of Story. 25 pages to realize that fact is ridiculous. That is how it works, Holtzauge. At 31.4% MAC the Spitfire Mk IX will act just like the NACA Spitfire Mk IX. The rear CG limit for a normal ie without rear fuselage tanks Spitfire Mk IX is ~36.3% MAC and the Take OFF WT CG is ~33.8%MAC. That is 33.8%MAC - 31.4%MAC = 2.4% AFT of the NACA Spitfire Mk V. :thumbup: http://forums.eagle.ru/showpost.php?p=2528059&postcount=150

500kph IAS like the Flugzeugen Handbuch says! :smilewink:

Exactly. Like many Bf-109 fans, there seems to be this perception that stability is fixed and does not change in an aircraft. The lateral instability of the Bf-109 is a good example. Flying qualities of an aircraft change with velocity and condition of flight. It is not a single characteristics under all conditions. It changes and is linked to loading, configuration, load factor, velocity/Coefficient of lift, drag changes, etc... http://forums.eagle.ru/showpost.php?p=2528533&postcount=166

Manufacturing tolerances were a concern to the RAE and Supermarine engineers in regards to the longitudinal stability of the type and were critical to the design. http://www.spitfireperformance.com/Spitfire_IX_ML-186_Handling.pdf

Please find any Stability and Control engineering text which list's Ballasting as a method of correcting the CG limits. You cannot. Why? It does not change the limits of the CG range. Your "ballasting theory" has nothing to do with the allowable limits of the aircraft's stability margin nor does it alter the NACA conclusions of the Spitfire series. No change in the AC to rear CG limits = No change to the Stability of the aircraft. EWCG = Empty Weight Center of Gravity I told you this back on page 20, Pilum.

:thumbup: Looking forward to the finished product!

Apology for what? Having a late war tail modification? Why do you think the RAE was so concerned with manufacturing tolerances for the elevators? http://www.caa.co.uk/aandocsindex/29016/29016000000.pdf Looks like G-BUWA got one of the "good manufacturer tolerance" elevators the RAE was so worried. :thumbup:

Missed this... http://www.caa.co.uk/AANDocs/23951/23951000000.pdf

Ballasting is a red herring. It does not effect the CG limits and is used only to prevent adverse loading conditions from developing when the CG changes in flight for specific load conditions. Permanent ballast is used to bring the empty weight CG back to the same position it was before the equipment or configuration was changed. The whole ballasting thing is just white noise that has little to do with the conversation.

You mean this one with the clipped wings and modified elevator? The one you are trying to pass off as having normal wings, no modified elevator by swapping the old UK CAA type sheet? http://forum.keypublishing.com/showthread.php?20144-Spitfire-Crazy-Mk2 http://www.caa.co.uk/AANDocs/23951/23951020000.pdf

Interesting information and thanks for sharing it. Now, just find where it mentions the clipped wings on the Spitfire Mk IX weight and balance sheet and it will give you the instructions. Otherwise, the weight and balance sheet is not referring to clipped wing variants if it is not mentioned.

There is no change in the normal wing design from the Spitfire Mk I to Mk IX that affects the aircrafts AC. Changes were done to change the stick force per G for controllability. No increase in the arm from the wing AC to the horizontal stabilizer/elevator AC = No movement of the Aircraft's AC. Increase the frontal fuselage length simply increases the moment about the CG required. The tailforce lift was increased. This has the same effect as dialing in some trim increasing the stick forces per G at a specific point. There is some stabilizing effect from horizontal dihedral but it is obviously not much gauging from the reduction in CG limits of Modern flying examples of the Spitfire Mk IX.

Yes...the AC was not moved and with the same CG limits neither was the stability margin. You keep overlooking that fact attempting to turn the argument into something it is not whilst trying to imply I am an idiot.

If it was the same for the Spitfire Mk IX.... It would be listed on the Spitfire Mk IX weight and balance sheet as well. Read AP-2095. You follow the specific instructions for each aircraft as outlined in its instructions. The Spitfire Mk VIII wingtips are not the same as removing the tips on a standard wing to convert it to clipped wing. http://www.spitfireperformance.com/spitfire-VIII.html

Weight and balanced is calculated every time you fly, Milo. Once more, in the military, Part 135, and Part 121 the pilot has to sign off on the flight acknowledging that the weight and balanced was checked. So it is not any different than any other flight, different numbers but no additional steps required regarding weight and balance. They would not be recalculating the limits either, they would be told the standard limits for that configuration.

It is clipped wing... Already discussed that changing the wing area will move the AC and change the stability margin. Once more, we do not have a weight and balance sheet for a clipped wing aircraft to see what the wartime CG limits were set too.

The Neutral point determines the rear CG limits. That is not the same thing as the Neutral IS the rear CG limit. That limit is set according to modern stability and control standards at the onset of instability. The Spitfires limit was pretty much set during the war based on pilot opinion on what he thought he could control. That is why all the normal wing Spitfires have restricted CG limits compared to their wartime counterparts. The Spitfire stability and control was not designed under a set of standards. It was designed by collaboration of the engineers at Supermarine and a small group of company test pilots. It is based on those pilot's opinions and subject to their ego. That is how most airplanes were designed in the late 1930's which is why the NACA tested so many when it adopted standards.

Good question and interesting bit of trivia!