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Subject: How to fix the design defects of the Spitfire airplane of WW-II.
Shooter    5/26/2005 5:12:16 PM
Given 20-20 hind sight, It is easy to see where R.M. went wrong with the Spitfire! The following list of items is my idea of how they should have done it, IF THEY HAD READ ANY OF THE COMMON TEXTS instead of designing a newer SPAD for the last war! 1. Start with the late Seafire or even better the Martin Baker MB-5! they have contra props and wide track gear. The MB-5 also has a much higher LOS out of the pit forward. This is also one of the Spits larger problems. 2. Change the shape/planform of the wing and eppinage from eliptical to trapiziodal. The eliptical surfaces caused the construction time and cost of the Spitfire to be more than double that of the Mustang and almost as much as the P-38. 3. Reduce the wing cord and thus area by 35-40%! This reduction in surface aria will increase the cruising speed substantialy! This is probably the single biggest defect in the design. The change in aspect ratio will also help fuel ecconomy! 4. To compensate for the increased landing and take off speeds install triple slotted fowler flaps with a long hinge extension. This gives a huge increase in wing area and changes the camber for supirior "DOG FIGHT" ability, should you ever need it! ( because the pilot really screwed up!) At full extension and deflection, they would reduce the landing speed by 11~13MPH? (Slip Stick calcs!) 5. Remove the wing mounted radiators and install a body duct like the P-51 or MB-5! This one change would add ~35MPH to the plane? 6. use the single stage griphon engine and install a "Turbo-charger" like the P-38 and Most American Bombers had. This would increase power and save weight, both significant contributers to performance. 7. Remove the guns from the wings! This would lower the polar moment of rotation and give the plane snappier rates of roll! It also makes room for "wet wings" with much more fuel. A chronic Spit problem. It also fixes the Spit's gunnery problem of designed in dispersion! 8. Install the Gun(s) in the nose! Either fireing threw the prop boss/hub or on either side 180 degrees either side of the prop CL. This fixes the afore mentioned dispersion problem. One bigger gun between the cilinder banks or upto four 20MMs beside the engine or both, depending on what your mission needs were! 9. Make a new gun based on the American 28MM or 1.1" Naval AA ammo! This shell was particuarly destructive, had a very high MV and BC and was all ready in service. A re-engineered copy of the existing gun to reduce weight and increase RoF is a faily simple task. Pay the Americans for it if British spring technology is not up to the task! it also frees up much needed production capasity for other things. 10. Design a new drawn steel "Mine" shell for the above gun! Spend the money to load it with RDX instead of the TNT used for the first 4/5s of the war. 11. Pay North American or Lockheed to design it for you, since the Supermarine staff was to tied up fixing the origional spitfire design to get it done any time soon. Did I miss anything?
 
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larryjcr    RE:Mach Limits   12/13/2005 10:02:42 AM
Also, I assume that a different flight profile was used for the Mustang. As the S.C. of the Allison Mustang was only a little above 30K, they obviously didn't start at 40.
 
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larryjcr    RE:Mach Limits   12/13/2005 10:15:25 AM
A P47 could not abort a dive by 'popping the recovery flaps'. The dive recovery flaps had to be extended before or immediately following initiation of the dive. The small electric motors that opened them weren't strong enough to do it after compressibility was encountered.
 
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larryjcr    RE:Extra fuel spitfire   12/13/2005 10:30:46 AM
The problem with Spitfire range was built in to the design from the start. The MkVIII stretched the wing structure as far as it would go, and gave a range on internal fuel just over half that of a Mustang or Lightning. Range of a MkVIII at economical cruise was about equal to a P47D at maximum cruise power. If Mitchell had been asked for something with more range, he'd have delivered, and they might have called it a 'Spitfire', but it wouldn't have been the same a/c. The RAF eventually realized that they needed a long range fightr, but much too late. Note that they were as quick to jump on the idea of a Merlin in the P51A airframe as was the USAAF.
 
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MustangFlyer    RE:Mach Limits   12/13/2005 4:10:34 PM
Just quoting from E Morgan & E Shacklady's book (bible?): Spitfire. Probably the definitive book, even has every serial number. These results were taken from the Aeroplane and Armament Experimental Establishment, at Boscomb Down, tests. I suppose you would have to go to the Public Record Office to in UK to verify this, but the reports quoted seem pretty credible (gives dates, speeds, serial numbers of planes used, even pilots). Re the Mustang, yes your right, it's flight profile was lower. Max speed at 17,000 feet diving from 28,000 feet.
 
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larryjcr    RE:Mach Limits   12/14/2005 3:25:30 AM
Guess I'll have to try and hunt up your book. Does it include description of the special insturments added? The possibility of insturment error giving excessively high speed data still seems the most likely answer. The data as given is hard to credit. We are dealing here with Critical Mach (speed at which an airframe begans to generate Mach shockwaves. For the P38 this was about .675 M. By your description, the P47 was well past Mcr at .75 M. For modern (F15, F16 etc) fighters, Mcr is in the range of .8 - .9 M. It's hard to believe that a straight wing WW2 fighter had a Mcr of .85. Any a/c with a fixed horizontal stabalizer exceeding Mcr is going to suffer tail buffeting, control lock and 'tuck' due to the change in the airflow off the wing.
 
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larryjcr    RE:P-38 dive limits...   12/14/2005 3:53:00 PM
To Shooter: In one of your earlier posts you said that the Mustang'e fuselage tank equaled the total tankage of an early Spit. Not so according to my refs. Mustang rear fuselage tank was 55 gal. Wing tanks were 110 gal. each. This compares to 85 gal. in early Spits, upped to 95 in the MkIX plus 2x 14 gal. wing tanks in the MkVIII. Total compat-usable internal fuel: MkI - 85, MkIX - 95, MkVIII - 123 gal. Mustang: 275.
 
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Shooter    RE:Care to provide proof/ Hurri v spit   12/15/2005 3:57:12 PM
Shooter's Origional post>A weapon with twice the range, will be 41% more effective than one with less range. It will make 41% more intercepts, RTB 41% more offen and thus reduce the Non combat, "Opperational" losses and in general do a better job than a weapon system with less range.< AE's reply>>Care to provide proof for this statement. As far as I can tell you are pulling these numbers out of you know where. You could possibly elaborate on your vague reference to game theory. Maybe you could produce the "equation" that gave these numbers. As I've pointed out before, despite having a far longer range than the Bf-109 the Bf-110 was cut to shreads over Britain. It's extra range didn't make it any more effective did it.<< The formula for the improvement factor is equal to the square root of the differance. I first learned this in A Game Theory Class in the early '70's? That the Me-110 was not nearly in the same performance class as the single engined types. But the twin engined P-38 was much better than any of the BoB types, as far as K/L and K/E ratios. It is my contention that the combination of effective speed and concentrated fire made the P-38 great.
 
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Shooter    RE:Extra fuel spitfire   12/15/2005 4:04:44 PM
>>Both of those fuel tanks were put in fighter spitfires with full armament.An extra 550 pounds of fuel and fuel tanks would only add an extra 18% induced drag to the aircraft. The spitfire already had minimal induced drag due to it's elliptical wing.<< Reduced Induced drag from the eliptical wing does not equal the increased drag of the increase in skin friction and reduction in aspect ratio. Secondly, the right corrrection for the weight increase should be -5.4% not the 18% you list above.
 
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Shooter    RE:Extra fuel spitfire   12/15/2005 4:44:43 PM
Great post Mustang flier! I note that the actual thickness of the Spit's wing is 36 Cm! at the root. The equivilant dimention of the Mustang wing was only 35.5Cm!!!! It was the T/C ratio were the Spit's wing was thinner!
 
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Shooter    RE:Mach Limits   12/15/2005 4:53:04 PM
Great post Larry! By the way, the Stang's Mcr is .705! At least from all that I've seen. I would be amaised to see the 'bolt at .75! Just look at that big blunt nose!
 
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