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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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oldbutnotwise    RE:Spitfire Kills and Claims   1/6/2006 4:56:45 AM
Shooter by the way can you provide evidence of this US superiority in strength you quote? or is this another "IMO" quote your prone to
 
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AussieEngineer    interesting...   1/6/2006 5:12:07 AM
Quoting Shooter: "If the ratio between empty and laden weight was increased range goes up by the LOG of the differance. See DeMairs formula?"
Just did a quick run through of shooters posts and "demair's formula" caught my attention. So I google it and only came across this quote which mentions it: "Demair's(spelling?) formula states that the depth of perforation is inversely porportional to the ratio of the jet and target densities" Source for quote But that isn't the really interesting part. The really interesting part is that the person who made that quote is who I believe to be none other than shooter himself. So what is "Demair's Formula"? A formula for calculating range based on empty and loaded weights or for calculating shaped charge penetration based on jet and target densities? I find this somewhat intriguing to say the least.
RE the actual subject of the post. A spit VIII with a 90 gallon drop tank* has an extra 525 miles range, which roughly translates into an extra 200 miles radius. This added to normal range of a MkI spit would result in a radius of about 400 miles, which is about 150 miles from Berlin, depending if you take off from Kent or Biggen Hill. *(which is the amount of fuel I suggested to give a 400 mile radius, albeit a radius to be achieved with careful fuel management)
 
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oldbutnotwise    RE:interesting...   1/6/2006 5:35:21 AM
doesnt supprise me he has taken to quoting larry on the autogun site to justify his statements implying that this site agrees with him
 
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larryjcr    RE:Spitfire Kills and Claims   1/6/2006 1:23:07 PM
To Shooter: Ref Spitfire hub gun. I admit I'm talking from pictures and a model, but the prop shaft is in line with the engine block, precluding a hub gun unless the prop shaft is geared from the engine drive shaft to raise the level high enough so that the gun can be mounted between the cylinder blocks. That would mean that either the thrust line rises, or the engine mounts have to be totally redesigned to lower the entire engine. The change in the front end of the P40D vs the earlier Tomahawks resulted from a far smaller change in the spur gear of the Allison changing the length and thrust line of the engine. Either way, the cowling of the Spitfire would have to change handle the alterations. Ref fuel in wings. In the MkVIII airframe, fuel tanks were added to the wing leading edge totalling about 35 gal. I assumed that could be increased by altering the armament in a different way, reducing the leading edge space occupied by gun barrels, etc.
 
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larryjcr    RE:Spitfire Kills and Claims   1/6/2006 1:43:34 PM
To OBNW: You should check out the article I mentioned ealier in this thread from AVIATION HISTORY magazine. Sufficient range is an absolute requirement for air superiority in anything except a totally defensive situation The short range of the Spitfire was a constant headache for the RAF. It was the primary reason for the utter inability of Ftr. Com., in spite of a massive advantage in numbers, to achieve air superiority over even those portions of the European coast opposite Britain. It meant that the RAF could not mainaint pressure on the Luft bases, even within the limited range of their primary fighter a/c. It can be debated that greater range would have been an advantage in the BoB, but there isn't any question about its critical importance for the rest of the war.
 
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Shooter    RE:Spitfire Kills and Claims   1/6/2006 6:16:49 PM
>>shooter your talking balls again the 20mm will not fit inthe nose of a spit without major redesign as they are TO LONG!<< If the instalation is REQUIRED from the start, so that it is not a redesign, but the origional, the gung fit nicely! Imagine the breeches under the Fuse main tank and the ammo displacing the fuel or the gear, either one. The engine either sits where it was or is relocated down ward in the fuse using the extra depth that is allready there. The air box plumbing has to be reworked and the motor mounts must be different than they were, which at the initial design stage, is no big deal. As to the length of the gun, just think of the back of the breech beside the pilots feet if neccessary! Look at a engine cut away and then imagine the fuse skin oval around it. The cilinder heads are ~30" wide IIRC and the pan is 14! That leaves 6.5" either side to mount the main body of the guns.(4) Two on either side. The changing thrust line is a non issue if it was done at the initial design stage, but does not matter in either case as ther is more than enough room below the engine to lower it while not changing the prop axis. There is so much room under the cowl that the inlet manifold, intercooler air box and supercharger out let can all be raised as the engine is lowered such that the engine mounted gun could be a M-61 Gatling type gun between the cylinder blocks! It would fire threw a blast tube in the prop spinner boss. To conceptualise this think of it as a fresh sheet of paper design from the fire wall forward! My sincere appologies about the Demairs formula! I screwed it up and recalled the wrong name! It was some French Guy who's name now escapes me, but invented a formula for range that now recognised as the correct one. I just recalled the wrong name. A cluttered mind is a terrible thing to live with. If it is not who I said, I will have to look up the right guy. None of the previous changes the idea of the origional post, range can be easily computed and the weight of the guns is a significant contribution to reductions in range that might be suffered as a result of converting a PR Spit to a combat plane. Note that ALL of this still equals the idea that the Spit was deficiant in range and that we now argue how to best fix that deficiancy not wether it exists! The more I am exposed to the ideas and research from the members of this board, the more I belive that the Spit was probably the single most over rated plane of the war. There are now known to me at least a dozzen refferances from this thread and others that cloud the Spits K/L ratio and might indicate that it was not positive at all! If this is so, would that change your mind about the Spit's value to the Brit war effort?
 
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AussieEngineer    RE:Spitfire Kills and Claims   1/6/2006 11:33:40 PM
"To get a handle on this in practical terms, think of the Allison engined Mustang 1, it was much faster(390MPH to 355MPH) than the Spit, on less power, while fliing at a much larger gross weight and at a lower altitude! All things that should have made it much slower, but the 'stangs AR was much better and it showed! Not that the AR was the only thing that gave it the edge, as the Radiator instalation helped too and the laminar flow wing, IF IT WAS CLEAN, did not hurt either. But the single biggest factor was the increased AR!" So I suppose that is why the P-40 was so much faster than the Mustang. But it isn't despite having a larger aspect ratio. Also the spits with extended tips. They have an aspect ratio of 6.5 compared to 5.8 for the Mustang. They aren't magically faster than standard wing spits. The advantage of high aspect ratios becomes less and less as the aicraft gets faster.
 
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flamingknives    RE:Spitfire Kills and Claims   1/8/2006 8:07:46 AM
My sincere appologies about the Demairs formula! I screwed it up and recalled the wrong name! It was some French Guy who's name now escapes me, but invented a formula for range that now recognised as the correct one. I just recalled the wrong name. A cluttered mind is a terrible thing to live with. If it is not who I said, I will have to look up the right guy. If you could look it up, I'd appreciate it. Sounds like an interesting formula.
 
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Shooter    RE:Spitfire Kills and Claims   1/8/2006 4:39:20 PM
IIRC, now? the guys name was Breuget, SP? Note the link below, which may or not work. To my utter amaisment, cut and past worked? WEB RESULTS Hypersonic Waveriders, Scramjets, Aerodynamics ... The waverider is the fastest wing of all, the wing for Mach 6 and beyond ... Using the Breguet range formula, Kuchemann concluded that a non-stop trans-atmospheric flight at ...aerodyn.org/Wings/waverider.html
 
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flamingknives    RE:Spitfire Kills and Claims   1/8/2006 5:26:13 PM
That seems to be the chap. Thanks.
 
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