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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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AussieEngineer    RE:Larry - The point   7/10/2006 4:44:59 AM
"The entire basis of energy tactics is that altitude and speed are interchangable forms of energy." Something that Spitfires do very efficiently. "The intitial zoom favors the heavier, higher wing-loaded a/c" Only at very high speed or if the climb is done at less than full throttle. "This is why the yo-yo was usually a better move than following the turn. It allows only a brief shooting opportunity, but much better chance for an aimed shot." Yet a Spitfire will produce a longer lower deflection firing window than a Fw-190 when it does a yo-yo. As I've said before it loses less energy while tracking the target in the dive and especially when it pulls lead for the shot and can do so for longer due to it's lower wingloading. It will also lose less energy when it breaks off into a climb. "If the attacking a/c had a much higher speed than the target, the target could turn inside it, whatever kind of a/c it was, forcing it to overshoot. If the pursuing a/c's pilot is VERY quick in recognizing the maneuver, he has a chance of a fleeting shot before he overshoots." And the pilot with the aircraft with the better turn performance won't have to be as quick because he can turn tighter and longer to get lead. He can also break off later with less energy loss. He can then also re-attack sooner because he reverse in the verticle faster. "Primarily, as I've said before, a tight horizontal turn is a defensive maneuver, used by the target a/c to shake off an attacker who has advantage." There is no denying that, but it doesn't change the fact that being able to turn with minimal energy loss in both horizontal and verticle is advantageous in all combat.
 
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AussieEngineer    RE:Larry - Roll Rates   7/10/2006 4:50:55 AM
"To MF: Funny that it didn't seem to work in either mock dogfights or actual combat, then. Or were they playing games with stick pressure again??" There is really nothing to support your statement that the P-47 out roles the spitfire 2:1 everytime, except for a single pilots recollection in circumstances unknown. Yet there are a raft of sources that are contrary to your view. What are you keeping to yourself that can over rule them.
 
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MustangFlyer    RE:Larry - Roll Rates - Credibility   7/10/2006 5:13:33 AM
"Or were they playing games with stick pressure again??" Obviously you have not read the report. NACA Report 868. Summary of lateral Control research". Compiled by Thomas A Toll. 1946. A summary of all the aileron control reseach undertaken by NACA since 1937 (includes references to work done by the British and Australians as well). 76 pages, 91 references. Covers analyses of different types of ailerons, aerodynamic effects, mechanical issues, compressibility issues, etc. There are many charts, tables and equations. Toll (the complier) had a long and distingushed career, for example I found a reference to him on the X-15 project (“The X-15 Project, Part 2-Results and new research”). To accuse all the researchers, aeronautical engineers and test pilots at NACA involved in all this work over many years, of playing games is frankly a bit reprehensible. They were some of the premier US (and world) aeronautical engineers and scientists of their era. The obvious retort to this dismissive comment is: "if you are so good that your opinions are more credible than the research staff of NACA netween 1937 and 1946, then where are your qualifications (must a PhD at least) and a list of papers that you have written and had published in the aeronautical journals". Until then your opinion on this matter must be judged as less than credible.
 
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MustangFlyer    RE:Summary & Roll Rates - Additions   7/10/2006 5:34:42 AM
During 1954, the NACA, in partnership with the Air Force and Navy, further explored the hypersonic aircraft concept. The agency's Langley laboratory (later NASA's Langley Research Center) had formed a hypersonic study team comprised of chairman John V. Becker, Maxime Faget, Thomas Toll, N. F. Dow, and J. B. Whitten, and this group subsequently evolved a baseline design that closely resembled the ultimate X-15 configuration. Polhamus, Edward C.; and Toll, Thomas A.: Research Related to Variable Sweep Aircraft Developments, NASA TM 83121 (1981). Thomas A. Toll, Leslie E. Schneiter; Approximate relations for hinge-moment parameters of control surfaces on swept wings at low Mach numbers; naca-tn-1711; Oct 1948 Highlights of Research by Langley for the F-111 Thomas A. Toll, responsible for the stability portion of the variable-sweep program, assigned William J. Alford, Jr. and Edward Polhamus to the task. In 1959 they arrived at the breakthrough solution, which was to locate the pivots of the movable wing panels to positions outboard of the fuselage. With this outboard wing-pivot arrangement, sharing of lift between the fixed inner wing and the movable outer wing panels minimized the movement of the aerodynamic center of lift. A fourth configuration, known as configuration IV, was added to the research program to confirm this design concept. The configuration was tested across the speed range in Langley tunnels with great success. Langley's ad hoc hypersonic aircraft study group consisted of John V. Becker, chairman, chief of the Compressibility Research Division and principal designer of the lab's pilot 11-inch hypersonic tunnel; Maxime A. Faget, a specialist in rocket propulsion from the Performance Aerodynamics Branch of PARD; Thomas A. Toll, a configuration and control specialist from the Stability Research Division; Norris F. Dow, a "hot structures" expert from the Structures Research Division; and James B. Whitten, test pilot. Unlike the Brown study group, this group obviously included some researchers with previous experience in hypersonics. Not quite the person to play games.
 
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larryjcr    RE:Larry - The point   7/10/2006 6:28:01 PM
To AE: Actually, the Spitfire did it, but not as well as some others. The comparatively poor diving acceleration of the Spitfire was the reason the Luft types kept disengaging by diving. Clearly, from the quotes MF offered below, as late as the MkIX vs the '109G, German a/c retained the advantage in dive acceleration. Since zoom in combat is generally from fairly high speed, that remains a plus. Power loading becomes more and more dominant after the first few seconds, but its momentum that provides the energy being converted to height, hence speed and mass. There is little point in a Spitfire using a yo-yo against a '190 as he's playing to hip opponant's strength. In the descent, lead is pulled by roll, not pitch. Actually, its the pilot with the quicker roll rate that has the better chance. Remember, turn arc is controlled by 'g' rate and speed until you get down close to stall speed. Which is why the Spitfire was an optimum a/c (ignoring the Japanese) for angles combat, while the heavier US fighters had to develope more verticle styles.
 
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larryjcr    RE:Larry - Roll Rates   7/10/2006 6:39:33 PM
Much more than a single pilot's recollection. We have the Bascome Downs report comparing the FW190A-4 to the Spit V showing the FW with deciscively superior roll rate. We have the account of Robert Johnson describing his use of the identical maneuver in the spring of '43 against both MkV and MkIX Spits. We have the referrences of RAF Kittyhawk pilots in North Africa (many with considerable Spitfire time) describing the 'delightful ailerons' of the Curtiss and it's 'remarkable roll rate', as well as later RAF Mustang pilots, who agreed with Brown on the 'stang's roll advantage over the Spitfire. We have the Dec. 1942 Tactical report on the P47C, of comparative tests indicating the superiority of the P47 over both the P40 and P51 in roll rate, and the 1946 US Material Command report on combat assessment of the FW190D-9 indicating that it's best quality was a roll rate that exceeded that of the P47D and P51D, being exceeded only by the roll rate of the new P80 (jet) and the late model P38 (with power boosted ailerons). All of these are consitant with the conclusion that the roll rate of the Spitfire was inferior to several contemporary fighters, including the Fw190A and D, the P47, the P51, and even the P40.
 
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larryjcr    RE:Larry - Roll Rates - Credibility   7/10/2006 6:41:45 PM
To MF, no I haven't read it. Provide a link, or a site ad. and I'll be happy to take a look. Again, I recall that every pricipal of aerodynamics proves that a bumble bee cannot fly. Unfortunately, the bumble bee hasn't read those reports either, and just keeps on flying anyway.
 
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larryjcr    RE:Summary & Roll Rates - Additions   7/10/2006 6:43:25 PM
Nor, for that matter is Capt. Brown, who finished a thirty year career as the RNs top test pilot with two places in the Guiness book of Records, and a chest full of awards.
 
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Hop    RE:Larry - Roll Rates   7/10/2006 7:17:13 PM
We also have the AFDU evaluations. Mustang III (P-51B) Although the ailerons feel light, the Mustang III cannot roll as quickly as the Spitfire IX at normal speeds. The ailerons stiffen up only slightly at high speeds and the rates of roll become the same at about 400mph. and: Rate of roll: Advantage tends to be with the Spitfire XIV. As to the Kittyhawk pilots in North Africa, I suspect if they had time on Spitfires, it would be the early models with fabric ailerons, which had a poor roll rate. The later metal aileroned ones had a good roll rate, as shown by Naca, and as commented on by the AFDU, who consistently found them to be better than the P-51 and 109, and generally inferior only to the Fw 190.
 
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AussieEngineer    RE:Larry - The point   7/11/2006 9:27:35 AM
"Since zoom in combat is generally from fairly high speed, that remains a plus. Power loading becomes more and more dominant after the first few seconds, but its momentum that provides the energy being converted to height, hence speed and mass." It is high speed, but not that much faster than the top speed of the fighters. If it really were at very high speed the spitfire would have the ultimate advantage of having the highest dive speed of any WW2 fighter. It also has good elevator control even at high speed unlike the Bf-109, which was a very effective verticle dogfighter. "There is little point in a Spitfire using a yo-yo against a '190 as he's playing to hip opponant's strength. In the descent, lead is pulled by roll, not pitch." Lead can't be pulled by roll alone. Roll only changes the direction in which the pitch is changed. "Actually, its the pilot with the quicker roll rate that has the better chance. Remember, turn arc is controlled by 'g' rate and speed until you get down close to stall speed." Wrong. Practically any WW2 fighter could be put into an accelerated stall. Stalls are dependent on AoA of the wing not air speed. You don't have to be going that slow to get into an accelerated stall. The Fw-190 was notorious for it's accelerated stalls. http://www.zenoswarbirdvideos.com/Images/P-51/P-51OLL.gif"> Also for the same amount of g, a Spitfire will have to pull less AoA, consequently it has less drag and lower energy loss throughout any change in pitch. That is why it gets a longer, lower deflection firing window. First, it can pull more g initially and for a longer period of time for the same loss of energy through drag. Secondly it doesn't have to have to pull out at gradually to minimise energy loss. There were very few aircraft that could respond to repeated slashing attacks by a Spitfire but in anything but a purely defensive manner. Where as a Spitfire if attacked in this way by Fw-190s, it could spiral climb until any initial advantage of the Focke-Wulf is gone and they either have to break off and hope the Spits don't chase them or get shot down. However, back to the original point. If you can only attack when you have an altitude advantage you'd better hope that you don't run across anyone higher than you. I'd like to hear how a P-47 deals with a 109 or 190 with an altitude advantage.
 
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