Military History | How To Make War | Wars Around the World Rules of Use How to Behave on an Internet Forum
Fighters, Bombers and Recon Discussion Board
   Return to Topic Page
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?
 
Quote    Reply

Show Only Poster Name and Title     Newest to Oldest
oldbutnotwise    RE:How to fix the design defects of USAAC P-40 fighters in WW-II....   12/6/2005 1:09:47 PM
You ignore the mechanics of what was happening in compressibility. The tails didn't fall off the P38s, but failed when the structural load was exceeded at levels no Spitfire could have survived. and this statement is proved how? you claim that the P38 was less likely to come apart in a dive yet it was issue with the model till the end of its life, the dive brakes was a fudge to get rround the problem not a fix. Can you provide evidence that the spit was weaker? as stated before the spit had the record for the highest dive speed achived and survived of any straight wing piston aircraft, this would imply that the spit could and did survive dives that caused the total loss of P38s The V/T for the Spitfire, as well as the speed of encountering compressibility were higher than for the Lightning. This was an unavoidable result of the '38s more lift-efficient wing shape. yet shooter claims the opposite, that the p38's wing was less lift producing threfore less drag, which of you is correct ? But the main cause was the '38s faster dive acceleration, compared to the Spit. If a pilot in a Lightning hit compressibility and tried to pull out in that range due to lack of understanding (or panic) the elevator controls were strong enough to actually increase the AoA, which only made things worse, and put increasingly powerful loads on the elevator and rear tail booms. If the pilot knew enough to throttle back and wait for denser air, he could pull out normally (although with a lot of Gs) and I know of no case of wing failure on a '38 in such a pull out. There were also cases in which pilots actually pushed the Lightning into an outside loop and survived, coming level, but inverted. intersting can you provive a source for this? I understood the compressability issue of the lighting was the opposite of this, it was its airdynamic shape that stoped the denser air from providing the source of recover (this denser air vs aero dyamics was certainly the cae in the p47s) Any properly designed and trimmed a/c would recover from the dive once the pilot started to pull back, and the pilot won't black out until the G forces of pull out are in effect. Nothing special about that. Check the book THUNDERBOLT by Robert Johnson/Martin Caidin for a description of exactly that in a P47. As to the '38 vs '109 collision, it was head on, prop-hub to prop-hub between the '109 and one of the '38s engines. The Lightning returned to base with one engine wrecked and smashed back a foot and a half in its mountings, both radiators on that side stripped off, the wing visibly swept back and that end of the horizontal tail hanging loose. It still flew and was still controllable. yet, according to one of the german aces, once downed a P38 by hitting it with a me109, the wing tip of the 109 struck the p38 wing inboard of the port engine taking away half meter of the 109 wing a futher colison with the tail boom put a 8cm hole out board of his wing gun, the p38 lost the whole port wing and crashed. I use this not to say the 109 was stronger but to point out that strange things happen. The Lightning was second only to the Thunderbolt and just maybe the Corsair and Hellcat, in being the structurally strongest single seater of WW2. Ithink this is rubbish as the IL2 was by far and away stronger(and it was a single seater to begin with the gunner was a later addition) as was the tempest, typhoon to name a few.
 
Quote    Reply

larryjcr    RE:Larry - from the horses mouth... Larry   12/6/2005 3:00:48 PM
The Spits could patrol over the beaches but could not drive the Luft from their own bases in occupited western Europe as the US fighters did. Neither the P47 nor the P38 was a failure as an escort fighter. While the early 'bolts had serious range limitations (they had only half again as much as the Spitfire), the later P47s could fly escort missions nearly as far a Berlin. The '38s had the range, but were largely diverted to the North African campaign were they were even more desperately needed. And the time the Mustangs arrived, the Lightning's early developmental problems had been dealt with. The problem was that the Lightning was in great demand in other theaters, and was available in more limited numbers than the 'bolt. The advantage of the P51 was that it was CHEAPER to build and operate than the other two, allowing very large numbers to be employed. The American hang up on range, proved essential in winning the war in Europe for the reason I mentioned. The extra fuel and oil tanks tested on the Spit MkIA fighter were underwing, between the inboard gun and the center pair. The efforts to increase range on the PR Spits weren't much use on fighters because they involved unportected tanks, or tanks that replace the guns. Ref accuracy, at least the USAAF bombers almost always found the right city -- something that the majority of RAF night bombers were not doing until at least the last half of '42.
 
Quote    Reply

larryjcr    RE:How to fix the design defects of USAAC P-40 fighters in WW-II....   12/6/2005 3:16:53 PM
The design philosophy of the Spitfire was for minimum wing loading, requiring that the a/c be kept as light as possible. Even RAF pilots agree that the Hurricane was stronger than the Spitfire. The Kittyhawk was at least as strong as the Hurricane, and the Lightning was much stronger than the Kittyhawk. The Lightning was not destroyed by the dive, but failed as a result of overstessing during attempts to pull out while still in compressibility that resulted in a high AoA. The same thing happened reapeatedly with Mustangs, and occasionally with Thunderbolts. Compressibiltiy resulted from loss of lift due to mach shock at the thickest part of the wind. All the dive flap did was produce an upward deflection of the airstream underneath the wing providing an up ward force replacing the lost lift. It was also used on P47s. I'd probably spot the Il2 due to my wording of the statement, but it certainly wasn't a fighter. My opinion is still out on the Tempest, but now the Typhoon -- that was the one that had external re-enforcements added because the tails kept coming off on ordinary dive pull outs, wasn't it??
 
Quote    Reply

larryjcr    RE:Larry - from the horses mouth... Larry   12/6/2005 3:54:02 PM
As to the P38 being a failure as an escort fighter, I'll offer an opinion from someone closer to the situation: following written by a B17 radio operator in the Fifteenth AF, 1944: Oh, Hedy Lamarr is a beautiful gal and Madeleine Carroll is too, But you'll find, if you query, a different theory amongst any bomber crew For the loveliest thing of which one could sing (this side of the Pearly Gates) Is no blonde or brunette of the Hollywood set But and escort of P-38s.
 
Quote    Reply

larryjcr    Compressability   12/6/2005 5:41:09 PM
To OBNW: The theory that shock waves from the wings or (in the case of a P38) the pilot's nacelle destroyed the tail in a compressibility dive was widely believed when the problem was first encountered. The P38 was the first a/c that flew high enough and accelerated quickly enough to seriously encounter it, but both P47s and P51s soon ran into similar problems. Working under that theory several tests were made with a '38 modified to raise the tail above the shock waves, and another with a canard elevator installed on the nose. Neither 'fix' worked. The NACA put a lot of wind tunnel time into this as well, and eventually (mid '42) the real problem was identified. They found that what was actually happening was that at about mach 0.675 at about 36K (for the P38, numbers varied slightly for other a/c) the airflow across the top of the wing hit Mach 1 resulting in a radical loss of lift, and the airflow off the wings changed, putting a major lifting force on the tail. This happened to ANY a/c in similar speed and altitude range. The result was very severe buffeting, the a/c trying to 'tuck' downward, and the controls becoming extremely heavy. When the pilot tried to pull up, the higher AoA he created, just increased the upward force on the tail, and the loss of lift. If this went far enough, it could destroy the tailplane, as a result, but it WAS the AoA increase, not shock waves by themselves. The fact that several P38s survived by 'tucking under' all the way into level, inverted flight clearly showes the immense structural strength of the a/c. If you want to try an outside loop at a true airspeed of 540mph+ at 35K + in a Spitfire, let me know. I'll send flowers. As I stated before, the dive flap caused a deflection of air that acted as a 'lift' effect allowing pull out. Please note that the dive recovery flap was mounted under the wind OUTBOARD of the tail booms and had no effect on the airflow over the tail. Before that, the system was to throttle back and wait for denser air to reduce T/V and increase M speed allowing control to be regained. The tactical problem was that if a P38 attempted a dive from very high altitude (say, in pursuit of a '109) he might run into the problem. As a result, German fighters were given a tactical advantage of escaping by diving away, while the Lightning pilots wouldn't follow. That was what the dive flaps ended. The real problem was that it took more than a year before all P38s in combat zones had the flaps. Similar flaps were instlled on later models of other US fighters.
 
Quote    Reply

AussieEngineer    Typhoon tails   12/6/2005 9:39:05 PM
I believe the reason for tails coming off typhoons was actually a result of vibration from the engine. In certain conditions it reached the natural frequency of the tail section, which caused it to part company with the rest of the aircraft. It just so happens that the conditions sympathetic to this behaviour manifested themselves in a high speed dive.
 
Quote    Reply

larryjcr    RE:Typhoon tails   12/7/2005 3:25:28 AM
To AussieEngineer. Okay. My source simply mentions a very high rate of engine and structural failures in early Typhoons, the latter being eventually trace to fatigue failures of the rear fuselage. I'd assumed the problem was entirely structural due to the nature of the 'fix'. I'd have thought that engine vibration would have been dealt with by mods to the engine mounts. Actually I just couldn't resist the dig. The external load it carried showed that the structure of the wings, at least, of the Typhoon were quite adequate. But with AGR giving me that rif about the tails coming off P38s, then offering up an a/c that did have a major problem of exactly that I just didn't have the strength of character not to say it.
 
Quote    Reply

AussieEngineer    RE:Typhoon tails   12/7/2005 5:34:02 AM
The source of the problem wasn't identified until much later, the attempts at strengthening the tail were done without really understanding the source of the problem.
 
Quote    Reply

larryjcr    RE:Typhoon tails   12/7/2005 12:33:06 PM
That explains those 'fish scale' reenforcement plates around the tail. A situation not too much different than the various test mods of the P38 built while working on the compressiblility problem. Talking about that, I forgot to mention the 'swordfish' Lightning, built with a greatly elongated pilot nacelle in an attempt to change the airflow.
 
Quote    Reply

The Lizard King    DEAR GOD!   12/7/2005 12:35:52 PM
Why does this thread keep going??
 
Quote    Reply



 Latest
 News
 
 Most
 Read
 
 Most
 Commented
 Hot
 Topics