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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:Liquid cool vs air cooled   5/2/2006 3:35:50 AM
First: I've always considered night fighters in a totally seperate catagory as in the WW2 period, the design requirements were totally different from single seaters. Which gets to the question of why, if the Hercules was so good, was it NEVER put in a single engine a/c??? I always assumed there was a diameter problem or something of the kind. As to the Merlin, where did the 2000hp come from. The 60 series was in the 1600hp range. To get to 2000 you needed to go to the Griffin. If you're talking overboost, then the P&W would rate 2800hp, and could maintain emergency boost much longer than the Griffin or Sabre. And, of course, all of them still have the vulnerability and complexity problems.
 
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MustangFlyer    RE:Liquid cool vs air cooled - Power   5/2/2006 5:01:53 AM
You've raised quite a few points Larry and I'm doing some research, so specific answer rigth now. However: Merlin 66, with 150 octane & 25 lbs boost (June 44 onwards, originally for V1 chasing then for TAF & the USAF's Mustangs) = 2,040 bhp. With water injection (P51H) = 2,400 hp. Not bad for only 27 ltrs. This is why the late 44 Spit Mk IXc ran rings around any A series FWs or 109Gs. The 190D and 109k were a bit more of a handful, but that is why they had the Mk XIV and Tempest. The Mustang boosted to 25lbs and clean (cleaned paint and removed drop tank stubs were in the 390-400mph range at 5,000 feet , nearly Tempest levels). The great thing about the 'stang was that it was fast at all heights! 150 octane allowed extra boosted P-47s and P-38s as well. See the SpitfirePerformance website, they have a full section on 150 octane fuel. Griffins were originaly boosted to 21lbs, then later 25 lbs (close to the end of the war after engine strengthening). Note the single stage Merlin 25s (used on the Mosquito Mk VI) were also boosted to 25lbs with 150 octane, as well as the Merlin 70 series used in the late model 'Cookie' Bombers (forgotten the model nums right now) and the Mk 30 night fighter. Merlin 66s only needed minor modifications to take the extra power, though the Mustangs used against the V1 switched to Spitfire exhaust stubs, still field replacable. The Sabre was also extra boosted (13lbs), late model Sabres (IIc I think, used in late Tempests) could be over revved to 3,000 hp.
 
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AussieEngineer    RE:Liquid cool vs air cooled   5/2/2006 8:22:35 AM
As far as I can tell there was nothing preventing the Hercules from being used on a single engine fighter. The only reason I can think of is that the Merlin was just that damn good. It weighed the same and had plenty of power and it had the advantage of smaller frontal area. I guess the British aircraft designers simply saw these advantages as out weighing those inherent in a radial design. As for diameters, I've done some quick scaling from 3 view drawings, I measured the wing span and compared it to the diameter of the cowling of for the beaufighter, hellcat and wurger. The beaus was 1.45m, the hellcats was 1.55 and the Fw-190s was 1.52. Given that there might be some error in my measurements and I was measuring cowling diameters not engine diameters, it is probably safe to say they are all pretty much about the same diamter. I believe the R-2800 only reached those very high power outputs with the use of water injection, correct? The Sabre at +11 lb, using ordinary fuel, was producing almost as much. Also, once they got all the bugs ironed out with the sabre it could practically run at full power all day long. As MF pointed out they were producing over 2000 hp with the Merlin from mid 1944 onward.
 
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AussieEngineer    RE:Spit XIV vs George   5/2/2006 9:02:30 AM
It is the combination of qualities that is important. If a P-47 did try to dogfight a spit, it would lose. The only thing it has is dive and zoom, it's roll is better at speed but at high altitude it wouldn't be likely to be able to roll faster except in a high speed dive. Where a spit has the advantage over the George is that in areas where the George is superior the spit is very close to it. For example, turn rate, the wing loading of both aircraft is reasonably close, about 5% higher on the spit. Unless someone objects and wants to do an in depth analysis with all the factors that affect, wingloading should be reasonably close accurate. I don't see why it would have better dive and zoom, they are similar weights and the George is obviously quite draggy, given it's top speed of 370 mph. The spit should accelerate better given it's lower drag and greater power at most altitudes. I don't know about roll but the spit was no slouch there either. It is very questionable that it had superior armament to the spit, it's 4 20mm cannon were slow firing and had a low muzzle velocity. They actually put out less weight of fire and had less muzzle power(KE at the muzzle per second) than the 2 Hispanos and 4 .303s of the spit. I also doubt that the George was more strongly constructed than the Spitfire, or had the same level of armour protection. It's engine was also quite fragile if memory serves me correctly. It may have been slightly tougher, but I doubt it would make much difference. So I'd say it was a strong possibility that a spit would be able to "mix it up" with a George reasonably confidently, but to do so would be giving away the massive advantage in speed the Spit has.
 
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AussieEngineer    RE:Interesting thing on Spit VIII range   5/2/2006 9:19:15 AM
The reason to compare those particular aircraft is because they were contemporaries, coming into service in significant numbers in 43 and because it provides a useful measuring stick of what the potential could have been with slightly larger wing tanks and a rear fuselage tank. An extra 10 gallons in each wing and 60 gallons in the back would have put a Spitfire VIII around the same ranges as the P-47D-25 was capable of. But the point being made was that if the RAF had the view that it wanted to have a long range escort, they could have made some relitively simply modifications to the spitfire. With drop tanks the range would be quite impressive considering the range of the Mk I.
 
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larryjcr    RE:Spit XIV vs George   5/2/2006 10:54:16 AM
First question: do your engine weight figures include weight of radiators and coolant, which the in-line HAD to have and the radial didn't need?? For a commparison of the two types, that would have to be included. The George was MUCH more agile due to the very best combat flap system of WW2. Even better than the P38s 'zap' flaps. In the N1K1/2-J during combat the flaps were controlled by an accellerometer (g-meter) that extended or retracted them at need. No other a/c of WW2 that I'm aware of had anything like this. The Spitfire always suffered from a lack of ruggedness (a high number of single-failure points in its structure). This was an unavoidable result of Mitchell's original efforts to keep the weight as low as possible. It's the down side of low wing loading. The '109 had the same problem for the same reason. In engineering there is no "free lunch". Every advantage has a down side. All a/c had single-failure points. The pilot was always one, for example and there were others involving the engine, with radials having far fewer. There were also points in the structure where a cannon shell, or 2-3 HMG hits would result in collapse under combat maneuver forces. The P47s reputation for ruggedness came from the fact that it had very few. The price was more metal and higher wing loading.
 
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larryjcr    RE:Interesting thing on Spit VIII range   5/2/2006 10:58:59 AM
The slowness of the RAF in finalizing on a proper drop tank for the Spit was a fine example of stupidity, however an 'extra 10 gallons in each wing' would have required the kind of restructuring that wasn't acutally possible until the MkXVIII of mid. '45. The British had to develope improved extruded structure technology and an entirely new wing spar design to make it possible. We've talked about the rear fuselage tank before, and I've explained why it couldn't be used to improve the combat radius of the MkVIII except in the absence of a proper drop tanks.
 
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MustangFlyer    The Jug   5/3/2006 2:33:54 AM
Excerpt from Charles Dills comments of the P-47, which he flew in combat, as well as the A-36 (the ground attackversion of the P-51A). From: http://www.charlies-web.com/WWII_med/letters.html Interestingly this also has some relevance to the P-47s range. I'm still collecting data and calculating results. "Did you fly the P-47? In combat? The P-47D was not a combat airplane. And neither was any Navy fighter! To explain, I flew the A-36A for 39 missions. It was a P-51A w/divebrakes. It had an 12 cyl Allison engine. I don't remember the numbers for it but I do know the numbers of the P-51D which I flew later in Louisiana. It would cruise at 290 ind (395 corr) at 10,000' and 255 ind (380 corr) (at 25,000) [2%/1000']. At 10,000 the P-40 cruised at 220 (264 corr) and the P-47D at 245 ind (294 corr). The fuel consumption of a P-51D25 (w/ Packard built Rolls Royce Merlin, 1503 HP) at cruise was 70 gph. At high power, combat settings it rose to about 90gph. A P-47D (much heavier plane) the cruise consumption was an acceptable 120 gph. But at combat settings the RATE of consumption would rise to 370 gph (from the tech orders, Part 4 Pilot Operating Instructions). This was because the cylinder fins were not adequate to cool the engine and instead it was cooled by dumping extra gas into the cylinder to go out the stacks unburned but carrying heat with it (Heat of Evaporation). This meant that if one were in a dust-up that lasted five minutes longer than planned, the reserve fuel would be exhausted and the plane would not make it back to the base. I know as sure as I'm writing this that there are many Navy pilots sitting in the bottom of the Pacific (and elsewhere) that never made it back to the carrier. I will never forgive the Navy brass that distrusted the coolant engines enough to kill thousands of their own pilots. We had one mission in Italy where none of the eight P-47's made it back to base. We were close to the lines but a number of them made it to other airfields and several bellied in on our side of the lines. I have between 600 and 800 hours in a P-40 (E, F, K, L, M and N models) and never had a problem with coolant. (I did abort one mission in Italy in an A-36A because of a pinhole leak that fogged the canopy!) And secondly, they capped the peacetime wonderful engine with a peacetime wonderful Hamilton Standard oil operated propellor. The oil was in the spinner and any penetration of the spinner by metal, gravel etc would cause a loss of oil, the blades would go flat and you wouldn't go far in a gliding brick! One of our pilots had that happen up around Pisa. He stayed with it till he got down to the clouds, around 4500', and then he stepped out and walked back. You didn't go into clouds in Italy, too many big rocks (mountains). The Allison engine had a Curtiss Electric combat propellor. The motor was in the spinner but if it got damaged, automatic locks fixed the propellor in its last position and you could at least fly it home. One of our pilots took a hit on the spinner of a P-40 that blew the motor off. He was able to fly it back to base. And thirdly, maneuverability of the P-47 at low altitude was bad, We did a lot of very low altitude straffing. The A-36A could be flown at 200' and when you saw a target, you could dip the nose, give a short burst and recover with minimum loss of altitude. The first week we had eight P-47's return with grape vines, fences etc because their planes almost mushed into the ground. We had to abandon that kind of straffing and strafe from 7-8000 feet., look for a target and then dive, fully visible to the enemy and shoot, remembering to leave plenty of room to pull out. The P-40 and A-36A could both be flown under 300', then dip the nose and strafe. The A-36A tech orders said (if I remember correctly) that 5% flap could be used at 350 mph and 10% at 300 mph. This would tip the nose down just a trifle but would minimize the loss of altitude. I'm not sure anyone ever did it but it was possible. And fourthly, the P-47 could never be used in a true dive bombing run. We didn't dare. We probably never exceeded a 60 degree dive. But with both the A-36A and the P-40 we could approach the target at 15000', extend the divebrakes (A-36A) fly upside down till vertically over the target and then pull straight down and drop the bombs from 4000 to 6000 feet and pull out. Vertical bombing is far more accurate. Glide bombing is not! Fifth, the P-47 could take a lot more punishment. But then again, you had to fly it in a way that it got more punishment. The A-36A and the P-40 both at 300' was on target and gone in seconds, they did not have time to react and shoot back. Furthermore, the A-36A's divebrakes had slots that created an eery whistling whine that seemed to come from everywhere. It would unnerve the gunners and then we were there and gone before they could do anything. The Germans were said to call us "the Screamin
 
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AussieEngineer    RE:Spit XIV vs George   5/3/2006 5:03:34 AM
RE radiator weight: I don't know, but I don't think so. But there wouldn't be that much difference, radials still needed supercharger intercoolers and oil coolers. Both of which are just as vulnerable as the coolant radiators on liquid cooled aircraft. Both also have serious consequences when damaged. About the george being more agile. I don't think so, agility is the ability to transition from one maneuver to another and to accelerate rapidly. It's like the comparison with the Spit II and Vs versus the early lightweight Fw-190s. The Focke Wulfs were considered more agile even though the spit had a tighter turn. I admit that the Spitfire was never the most rugged of planes but Japanese planes have a much worse reputation for ruggedness. Without actually comparing the actual structures of the planes it is very hard to say.
 
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AussieEngineer    RE:Interesting thing on Spit VIII range   5/3/2006 5:31:01 AM
An extra 10 gallons in each wing was easily possible. PR spits without any fundemental structural changes to the wing were able to carry 66 imp gal in front of the main spar and another 20 in an interspar tank. -An enlarged tank would be in front of the main spar -All the guns and cannon and ammunition are behind the main spar, only the barrels protruded through the main spar and out of the leading edge of the wing. http://img102.imageshack.us/img102/2028/spitwingtank9dj.jpg"> As you can see there is heaps of room for it. There is some minor structure in the way, but if the tank was integral with a self sealing coating applied to the inner surface that wouldn't present a problem and it would be perfectly safe as long as it was pressurised with exhaust gas. If you were really worried about it you could armour the back of the tank. Potentially a tank could extend the entire length of the leading edge, like on the PR versions.
 
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