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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:How to fix the design defects of USAAC P-40 fighters in WW-II....   12/9/2005 3:39:59 AM
To AussieEngineer: these limits (remember, the max level speed for a P38J was 420) were a result of the compressibility problem, not structural strength, did not apply except at high altitudes, and were ignored even there after the installation of the dive recovery flaps. They were the reason that '38 pilots rarely tried to follow German a/c in dives until they had the flaps.
 
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oldbutnotwise    RE:Larry - from the horses mouth... Larry   12/9/2005 7:27:37 AM
It is clear from these figures that the origional P-40(No Suffix!) was closer to the Spitfire in performance than the Hawker and vastly supirior to either RAF plane in range and cruise speed! While the early Spit could cruise <450 miles at less than 200MPH, the P-40 could cruise at 277MPH for 650 Miles! It is my contention that that differance, when added to the ease with witch it could be manufactured would have made the BoB much better for the Brit side. (It also would have made the Germans more likely to win the BoB outright had they had the P-40 instead of the Me-109E! what tosh, the p40 was vastly inferior above 9000ft in all of its versions, it would have need to cruise at very hight speed with the combat zone(the same need by the mkV spit after the introduction of the fw190) its performance at altitude was poor, whilst it could reach the required height it could not compete at that altitude as the later version found out over MTO. and bare in mind that the figures you quote are for a version with out armour or seal sealing tanks with a >>well as the p40 would have required an extra 20 minutes to get to altitude to intercept the aircraft would have been scrambled whilst the germans were forming up over france,<< Since the time to climb to 15K' was only 5.1 to 5.3 minutes and the initial rate was 2700 to 3100 F/M, AT LEAST ACCORDING TO rAY WAGENER'S BOOK aMERICAN cOMBAT pLANES PAGES 208-209, I sincerely dought that it would have taken anywere near 20 additional minutes to climb to the absolute cieling of any German bomber of the BoB era! Spouting bogus numbers without referances makes your argument look, well, bogus and weak! well if you take the values for a C model as you have done then Iam not supprised that your figures differ its amazing what a year makes >>The p40D/E of 1942 was completely outclassed by the me109e above 9000ft as was proved beyond doubt in the PTO so why would the inferior P40(no suffix) have been better in 1940? nearly all the bob was fought at altitudes of 15000ft+ << I suppose that the Hurricane was a match for the Me? The facts that you so convieniently ignore are that none of the planes involved had the range to get the job done and that range can be converted into speed. With the restrictions to throttle use neccessitated by the requirement to be able to fly home to the fields in France, even the lowely hawker had better performance than the Me-109E durring most of it's time over England! In fact the performance stats of the origional P-40(NO Suffix) from page 209 of Ray wagoner's book American Combat Planes, Curtis P-40, power1040HP, DIMENTIONS; Weights;5376Lbs EEW, Gross 6787, Max=7215 Lbs. Fuel=120-181 GALLONS! Top Speed @15K'=357MPH, cRUISING 277mph!, Absolute cieling 33,800', Climb=3,80FPM, 15,000'/5.3Minutes and RANGE 650Miles@277MPH, 950Miles@250MPH AND 1400Miles@188MPH! 5.3 minutes to 15k for tha P40 that is way off all other sources which have it over 8 minutes. yeah yeah your range into speed argument that no one on at least two sites will agree with. by the way your figures are not for a p40 but a p40C again! the RAF regarded the P40B as inferior to the Mk1 hurricane when it entered service in nov 1940 in fact so inferior it was relagaged to a training role! the later P40C was sufficeintly improved to be considered suitable for combat on the MTO. The realivant numbers for the early BoB Spit, from page six of Stewart Wilson's newest book are; Speed 355MPH(OTHERS LIOST VARIOUS NUMBERS UP TO 362MPH),MAX CLIMB 2530FPM, TIME TO 20K' 9.4 Minutes!, time to 30K'=16.4Min. and time to 15000ft 6.85minutes! ramge 650 miles complete book of fighters william green & Gorden Swanborough Note that ALL OF THESE NUMBERS ARE LESS THAN THOSE OF THE P-40! picking and choosing again arnt we! by the way the P40 first entered service in April 1940, the first full squadron was deemed "active" in October so you would have to fight the BOB with 1 squadron of these aircraft no more and one with no fight time either! your main fighter of 1940 would have been the P36 Hawk yet me see you try to justify that as better! a quick recap - the spitfire and hurricane both aircraft pre war designs were on paper faily equal to the 1940 P40, however as the RAF flew all three the fact that they relegated the P40 to training role must indicate that they thought that actual relality was something different to the paper figures! and the later P40D were out classed by the same bf109E's as the spit and hurricane faced in the BOB It is clear from these figures that the origional P-40(No Suffix!) was closer to the Spitfire in performance than the Hawker and vastly supirior to either RAF plane in range and cruise speed! While the early Spit could cruise <450 miles at less than 200MPH, the P-40 could cruise at 277MPH for 650 Miles! It is my contention that that differance, when added to the ease with witch it could be manufactured
 
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AussieEngineer    RE:Larry - from the horses mouth... Larry   12/9/2005 9:46:19 AM
100 miles radius is a bit excessive, but I did it to illustrate a point. The entire 11 group sector doesn't get much more than 120 miles across at the widest point. In all likelyhood, the radius required would be much less than 100 miles, they were essentially fighting directly over their own airfields, as you can see below. http://www.raf.mod.uk/bob1940/images/11grpmap.gif" width=400> The limitations in GCI may have made it impossible for a squadron to make another attempt at intercept. The sector HQ wouldn't know either the fighters or the bombers exact position. That would make it very difficult for accurate vectors to be given, which would result in another failed intercept. It may be better to get the planes back on the ground so they can be serviced and the pilots can get some rest. Don't get me wrong, extra range wouldn't have hurt, just so long as it didn't come at the cost of other more vital areas of performance.
 
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DropBear    RE:Larry - from the horses mouth... Larry   12/9/2005 9:59:33 AM
Ooooooooh, pretty! ;)
 
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AussieEngineer    P-38 dive limits...   12/9/2005 10:07:37 AM
The manual seemed pretty insistent about not exceeding those speeds. It says in bold "never exceed these speeds". The interesting thing shooter failed to mention is that 470 mph maximum dive speed for a spit (a XIV in this case) is IAS, the equivilent VNE IAS for a P-38 at 20,000 is 360 MPH, which is quite a bit slower. The 2 manuals (P-38 and Spit XIV) actually have a fair bit of comparable info. VNE For the P-38J or L 420 IAS @ 10,000 360 IAS @ 20,000 290 IAS @ 30,000 VNE for Spitfire XIV 470 IAS @ 20,000 430 IAS @ 25,000 390 IAS @ 30,000 340 IAS @ 35,000
 
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larryjcr    RE:P-38 dive limits...   12/9/2005 11:06:53 AM
I can only repeat: the limits were set to keep the a/c out of compressibility and were probably never officially changed, just ignored after the reason for them was overcome. They had to be set low due to the very high acceleration of the P38, especially in a dive. The later Spitfires could get into the compressibility range, but it too a lot more effort and dive time. A P38, going into a dive from service ceiling (42K) would be into that range within 8,000 ft of push over.
 
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larryjcr    RE:Larry - from the horses mouth... Larry   12/9/2005 11:12:42 AM
I don't see why a second intercept attempt would have been any more difficult that the first. The whole system of GCI including the ground observers and later the second echelon of radar stations was for the purpose of locating the incoming raids, and the intercepting ftr sqds. If the second attempt only resulted in a 40% success rate that would have brought the per sortie contact rate up from 50% to 70% without the need of a single additional pilot or a/c. Certainly a P40 type with a Merlin would outperform the Hurricane. The increase in intercepts would certainly more than compensate for a limited reduction in rate of climb. The Curtiss type could already out turn the '109 as the German's in North Africa admitted without hesitation.
 
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AussieEngineer    RE:Larry - from the horses mouth... Larry   12/9/2005 7:51:58 PM
This is my line of thinking as to why a second attempt would be unsuccessful most of the time. If they missed on the first attempt, then the controllers don't know the actual position of the bombers because they've changed course or the intial plot was wrong for whatever reason. The intercepting aircraft also probably do not know their precise location, which would further complicate the problem. So essentially the area of uncertainty would be much greater than what it would be for an initial successful intercept. Consequently the probability of making contact with target aircraft would go way down. At guess, it would be something less than a 10% chance of making contact. However, I'm writing at the limit of my knowledge right now. I'll have to do more research before I can say whether of not a second "buster" run would have resulted in a lot more successful interceptions. A merlin powered P-40 would have been able to take the place of the Hurricane, it would have required different tactics though. However, it still would have had inferior performance compared to the spit, which is what this is really all about.
 
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AussieEngineer    RE:P-38 dive limits...   12/9/2005 8:07:22 PM
Here's the link to the P-38 manual I've got. It just seems fairly insistent that one should never let the speed build up beyond those speeds. Dive brakes would have mostly allowed for steeper longer lasting dives not neccessarilly much faster dives. The onset of compressibility was just at much slower speeds for the P-38 than the Spitfire. Anyway there is the manual if you want to take a look, be warned it's 37 megs though. http://www.airwar.ru/other/bibl/p-38pilot.pdf
 
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larryjcr    RE:Larry - from the horses mouth... Larry   12/10/2005 2:40:03 PM
The controllers got the positions of both the incoming raids (once they came over land) from a system of ground observers, and later a second echelon of radars. The locations of intercepting sqds came from the same sources, plus reports by the formation leaders. Any of these might or might not be accurate. Course changes by the raids added another factor to the problem. I wouldn't think that a second intercept attempt would be much more difficult than the first try. The Merlin 'hawk would be only slightly slower than the Spitfire, nearly as good in turns, but with better roll rate and considerably improved endurance. The only real downside would be climb rate due to heavier a/c. The question is the tactical trade off between endurance and climb rate.
 
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