Interesting facts

Discussion in 'Warbirds International' started by bizerk, Jul 31, 2003.

  1. bizerk

    bizerk Well-Known Member

    Joined:
    Jul 14, 2001
    Messages:
    2,394
    Hi folks, i think most will find this interesting to read. foundout some good information from this book entitled "combat development in world war two fighter aircraft, by alfred price"

    check this out

    Improving The Performance

    by september 1940, a year after the outbreak of the war, the true situation regarding air-to-air combat had become clear : the ' state of the art ' fighter, with the aid of ground control using radar, was more then a match for the state of the art bomber. The fighter designs of 1934 had achieved what their builders had wanted of them. Yet there was no time for anyone to rest on thier laurels. Now bombers rarely opperated over enemy territory by day unless they had fighter escorts. This, in turn, meant that fighters vs fighter combat, which had seemed both unnecessary and unlikely before the war, now became the fighters primary role. The dogfight, which many had thought as out dated as trench warfare, was suddenly as important as it had ever been.

    If fighters were to fight each other as well as bombers, then additional qualities would be required of them. A high maximum speed and a high rate of climb were still of the utmost importance ; but to these were now added the requirement for good handling characteristics at high altitude and in the dive, and a high rate of roll ( this was more important
    then a small turning circle, because it enabled a fighter to change direction rapidly to take aim or shakeoff pursuit). Also a large radius of action, to enable fighters to escort bombers deep into enemy territory, assumed a new importance.

    The Spitfire remained in production from before the beggining of the war to well after the end. During the conflict it was developed to an exceptional degree, and in 1945 it wasstill a potent fighting machine ; an examination of the aerodynamic changes made to it will, therefore, serve to exemplify thegeneral pattern offighter development during the period. The intial improvements were all fairly simple ones : a slight increase in engine power, the fitting ofconstant speed propellers andthe fitting of metal instead of fabric covered ailerons to improvehandling at high speeds. From then on the evolution of the Spitfirecan be summed up as follows. A series of engines ofprogressively greater power were fitted, and these required progressively larger propellers to convert the extra power into thrust ; the prototype Spitfire had had a 2 bladed propeller, by 1939 thier were 3 blades, by 1942 4 blades and by 1944 Spitfires were flying with 5 bladed propellers. Aerodynamically, the propeller produced an effect on stability similar to that one would expect from a large cruciform fin on the nose, while the rotating slipstream round the fuselage tried to screw the aircraft into a roll ; with the fitting of larger engines and propellers these effects became more serious andhadto be corrected by increases in the size of the fin and tailplane, to provide thew necessary straightening moment.

    Simultaneously, airframes become much cleaner. The effect on maximum speed of various small changes to the airframe maybe seen from the following results, obtained during a trail in 1943 with a Spitfire V : maximum speed of standard aircraft, 357MPH ; with multi-ejector exhaust fitted in place of the older fishtail type, plus 7MPH ; with the carburettor intake icegaurd removed, plus 8MPH ; with a whip radio aerial in place of the older mast type, plus1/2MPH ; with a new type of rearview mirror with a front fairing, plus 3MPH ; with the ammunition cartridge case and link ejector chutes cut flush instead of protruding beneath the wing, plus 1MPH ; with the leading edge of the wing smoothed out by stopping, rubbing down, painting and polishing, plus 6MPH ; with the additional polishing of the rest of the aircraft using wax, plus 3 MPH. Together, these individually small changes increased the speed of the Spitfire V from 357MPH to 385- 1/2MPH, and difference of 28 1/2MPH. The retractable tailwheel, fiited to later marks of the Spitfire, was worth about 4MPH at 400MPH.

    If we compare the mark 21 Spitfire, the model in production at the close of the war, with the mark I in production at the begginning, we can get a fair picture of the effects of the developement o fthis fighter during the conflict. In each case the figures given are those of the mark 21, and their relation to those of the mark I are given in brackets : engine power 2,035h.p. (nearly double); normal loaded weight 9,900lbs. (nearly 3/4 more), at which the wing loading 40.5 pounds per square foot (2/3 greater) and the power loading was 4.9 pounds per h.p. (horse power) (4% better) ; intail rate of the climb was 4,900ft per minute (nearly double), maximum speed was 450MPH (greater by 1/4) andthe service ceiling was 43,000ft (greater by 1/3). The maximum take off weight of the Spitfire 21, carrying a full 170 imp (202 U.S.) gallon drop tank, was 11,290 lbs ; this was greater then that of the Spitfire I by a weight the equivalent of 30 12-stone passengers each with 40 lbs of luggage!

    One important airframe change which was not incorporated in the Spitfire during the second world war was the so-called " laminar flow" wing. This was a wing with an exceptionally fine finish : the surface roughness had to be less then .0005 of an inch and the maximum wave allowance was .0001 of an inch in any 2 inches of surface. The fineness of finish was combined with a high speed aerofoil section, with its thickest point about halfway back from the leading edge (rather then a 3rd of the way back, in a conventional aerofoil). The first aircraft opperational with the laminar flow wing was the North American P-51 Mustang, which entered service in the RAF in the summer of 1942. Late, re-engined with rolls-royce merlin with a two stage supercharger, the Mustang became one of the outstanding fighters of the war. The effect of the laminar flow wing can be seen if the performance of the p-51b Mustang is compared with that of the Spitfire IX ; the comparison is valid, because the two aircraft were powered by almost exactly the sametype of merlin. In terms of wingspan and area the Mustang's wing was closely comparable with that of the Spitfire ; the latters wing was 2 inches longer and about 4% greater in area. Yet in spite of the similarity in wing dementions and engine power , and the considerably greater weight of the Mustang (about 1/4 greater), the latter was appoximately 20MPH faster then the Spitfire IX for any given cruising power setting of the engine, andabout 30MPH faster at maximum speed. The main factors responsible for this were the laminar flow wing andthe high speed aerofoil.

    As has been mentioned earlier in this section, oneof the factors required by fighter pilots was the highest possible diving spped while maintaining full control. By 1943 the latest fighters were able to reach speeds during dives which were beyod the threshold of compressability ; the sound barrier was beggining to rear its ugly head. The effects of compressability varied from aircraft to aircraft ; on fighters with thick wings the threshold came quite early, at about .7mach (about 500MPH at 20,000ft depending upon temperature). As theaircraft advanced further over the threshold the effects became more and more serious as the shockwaves upset the airflow over the wings and effected fore and aft stability and gradually the pilot lost control of his aircraft. This placed the pilot in a difficult situation , since during these steep dives at angles of 60 or 70 degrees he was losing height at a rate of about 40,000ft per minute it was not difficult to lose as much as 10,000ft during the uncontrolable part of the dive, and to this had to be added a further 10,000ft for a safe recovery. Those who went to far beyond thier aircrafts compressability threshold found that they regained control at an altitude to low to pull out of their dive. Nobody did that twice.

    Two american fighters, the P-38 Lightning and the Republic P-47 Thunderbolt , suffered severe compressability effects at speeds below .7 mach. In the case of the latter the problem was aggravated by the fact that a sudden reduction in engine power during the dive cause a nose down trim change, which steepened the dive and increased the speeds still further. To assist the recovery from uncontrolable dives, later versions of both aircraft were both fitted with small dive recovery flaps under thier wings about a third of the way back from the leading edge; when lowered they caused a nose up pitching moment, which pulled the fighter out of the dive. The dive-recovery flaps on the thunderbolt were quite small, each with an area of 1.7 square feet, andthier maximum extention angle was 20 degrees.

    In the mid-war generation of fighters the phenomenon of compressibility was one which could beavoided in combat. With the firsst generation of jet fighters, however, there was no such simple way around the problem. At full throttle in a shallow dive at an angle of 20 degrees from 26,000ft, the Me 262 was well beyond its compressibility threshold before it haddesended through 7,000ft. The threshold was reached at.83 mach at which point the nose started to drop and a backward pull on the stick of about 30 pounds was required to hold the aircraft straight. As the speed increased still further a violent buffeting set in and the aircraft became progressively more nose-heavy, until at.86 mach (a true airspeed of about 620MPH at 19,000ft) a backwards force o fabout 100pounds on the stick was required to prevent the Messerschmitt bunting over into an uncontrolable dive.

    One aid which wouldhavebeen usful to the jet fighter pilots at this time was the machmeter, which gavean immediate reading of the relationship ofthe aircrafts speed with that of sound for the altitude at which it was flying ; but this device did not comeinto general use until after the war. In the case of the Me 262 the luftwaffe high command imposed an airspeed limitation of 595MPH (true), and gave strict orders that pilots were not to exceed it ; the similar airspeed limitation for the Me 163 was 559MPH.

    Somewhat worse off then the two german jet fighters from the point of view from compressability threshold were the marl I and III versions of the british Meteor. These suffered airflow breakaway at the outboard nacelle-wing junctions at mach.74 resulting in severe buffeting. Following extensive wind tunnel test a set of lengthened engine nacelle was produced andflown on a Meteor just before the end of the war ; these improvedmatters considerably and delayed the onset ofcompresability, andthe aircraft was taken to a new limit of.84 mach. After the war production Meteors with the longer nacelles were opperated to a limitation of .8 mach.

    Provided there was no aerodynamic weakness in the design which brought on the effects of compressability at a lower figure, it was the shapeandthe thinkness of the wing which usssually decidedthe limiting mach number. Before theend of the war the germans had discovered that the compressability threshold could be delayed considerably by the use of swept-back wings ; and several of thier projected fighters at the end of the war featured such wings. However, to get any major improvement in thiswayit isnecessary to sweep back to 35 to 40degrees. So it can be seen that the 18 degrees leading edge sweep back on the Me 262, or the 27 degrees on the Me 163 was not sufficient to delay the onset of compressibility by any great amount ; the two german fighters were good in this respect because they were clean aircraft, not because their wings were bent back a little.

    As hasbeen mentioned, the effects of compressibility could be delayed either by sweeping back the wing or by using a very thin wing. It was the latter that gave the Spitfire a mach performance unequalled during the second world war andfor some time after it. The Spitfire had the thinnest wing of any of the fighters of this period, with a root thickness of only 13% of the chord (this compared with 14.7% for the Me 163 and 16% for the Mustang). Once its original fabric covered ailerons had been replaced by metal ones, andthe aircraft had been cleaned up alittle with a retractable tail wheel, the Spitfire hadan outstanding mach performance. During a trial Farnborough in 1943 a slightly modified Spifire XI (a recon version of themark IX version fighter) was taken to .9 mach, a truely magnificent achievement for the time.

    Had the war gone on and combats between jet fighters become common place, it is likely that the problem of compresibility would have had a considerable effect of fighter tactics. In the past, the rule had been to try to get above ones opponent and dive on him with the advantage of speed. Now, with fighters almost able to reach their maximum controllable speed in level flight, excess height could become an embarrassment because even a shallow dive could place the aircraft beyond its compressibility threshold. To overcome this problem British and American designers fitted their jet fighters with dive breaks to enable theit pilots to hold down the speed during the descent ; Willi Messerscmitt, who was more interested in producing a vehicle for destroying the enemy bombers then one for jousting with his fighters, did not bother.

    most interesting A?? <s>

    bullet
     
    1 person likes this.
  2. RolandGarros

    RolandGarros Well-Known Member

    Joined:
    Mar 21, 2003
    Messages:
    2,867
    Thanks, that was a good read. I wonder if a P-38 fitted with 2 of those 2000hp late war RR Griffon engines & 5 blade props would compress in level flight at full throttle.
     
  3. By-Tor

    By-Tor Well-Known Member

    Joined:
    Jan 13, 2002
    Messages:
    314
    Location:
    Pennsylvania USA
    Great stuff Bizerk-thx mate! Not to mention the Spitfire was the prettiest damn plane ever designed. (By-Tor ducks head and runs!) :help:
    Chech squad site bro ....<S>
     
  4. Jacobe

    Jacobe Well-Known Member

    Joined:
    Jan 28, 2002
    Messages:
    3,340
    Location:
    Suomi,Finland
    thx nice interesting reading ...got 1 question..Which was the 1st plane to break sound barrier?? (I heard it was spitfire :dunno: )


    SPITFIRE 21 T05

    [​IMG]
     
  5. sebbo

    sebbo Well-Known Member

    Joined:
    May 9, 2001
    Messages:
    2,415
    Location:
    Sector Plural-ZZ Alpha
    Officially it's the Bell X-1, piloted by Check Yeager.
     
  6. Jacobe

    Jacobe Well-Known Member

    Joined:
    Jan 28, 2002
    Messages:
    3,340
    Location:
    Suomi,Finland
    So they tell here
     
  7. ozemale6t9

    ozemale6t9 Well-Known Member

    Joined:
    May 10, 2002
    Messages:
    815
    Location:
    Queensland's Southern Capital
    The Spitfire was the first piston-driven plane to break the sound barrier.

    And to achieve this feat, they had to put it into a steep dive. After several attempts without breaking the sound barrier (got close, but no cigars), some bright spark came up with the idea that the problem was wind-resistance. So the landed it, ground the tops off all the rivets holding the skin on until they were near flush, and took her up again. This time they had success.

    Not sure if that pilot was extremely brave, or extremely stupid, but luck must have been on his side.

    regards, Oz
     
  8. sebbo

    sebbo Well-Known Member

    Joined:
    May 9, 2001
    Messages:
    2,415
    Location:
    Sector Plural-ZZ Alpha
    I might be mistaken, but I believe that a plane like the spitfire would run into serious problems when exceeding mach-1. Its wings were still to thick to avoid compression, nor did it have swept-back wings (the two old-fashioned ways to make a plane stable at supersonic speeds).

    I also heard something about serious troubles with prop-driven planes at trans-sonic speeds. Had to do with something like cavitation (air-bubbles at a ship's screw due to high speeds)... At high speeds, you get small bubbles of vacuum causing tremors in the prop-shaft and blades, ripping apart both engine and prop.

    But then again, I aint no pro!
     
  9. Malino

    Malino Well-Known Member

    Joined:
    Jun 14, 2001
    Messages:
    1,594
    Location:
    UK
    The British were the first to break the Sound Barrier, same way it was the British that captured the Enigma machine from a German U-Boat, the British who invented Radar, The British who invented the Ejection seat, the British who invented the Steam Catapult used on aricraft carriers, the British who invented the Tank, etc


    Hollywood would just like everyone to believe it was the US of A that came up with all these things to promote the image of the US of A being the saviours of the world by making cheap tacky movies that are works of fantasy instead of being historically accurate.

    Mal
     
  10. ratpak

    ratpak Well-Known Member

    Joined:
    Jun 17, 2001
    Messages:
    110
    Location:
    Germany

    LOL WTG M8 :D :D :super:
     
  11. Pinky

    Pinky Active Member

    Joined:
    Sep 5, 2002
    Messages:
    31
    Location:
    Czech Republic
    I think none propeller powered plane can break sound barrier in level flight. I'm not an expert on aerodynamics so we hope to have a final word from someone who is deep into this, but I was explained some time it always required dive (and help of the earth) for the propeller fitted plane to break M1. The problem is that if that should be in level flight, there is big difference between the speed of the inner and outer part of the propeller that has caused problems near M1 (I'm not talking about the compression at wings that is mainly mentioned above). I think USAF tried with some experimental propeller fitted planes and they learned propellers are not the way to go if the plane should fly >M1.

    Pinky
     
  12. sebbo

    sebbo Well-Known Member

    Joined:
    May 9, 2001
    Messages:
    2,415
    Location:
    Sector Plural-ZZ Alpha
    That's what I meant, Pinky. Once the airflow reaches M-1, I think you'd lose all propulsion due to violent buffeting and vacuum-bubbles over a large portion of your prop-blades.

    Oh, and Mal? :D Great post, but not really relevant. You can hardly accuse ME of being "pro-american", can you?
     
  13. Comet-

    Comet- Well-Known Member

    Joined:
    Aug 7, 2002
    Messages:
    142
    Location:
    Prague, CZ
    Pinky:
    A propeller powered aircraft can break sound barrier, if you use a supersonic propeller :)
    That is a major problem for a ordinary propeller, because when you are near speed of sound, the propeller tips are already breaking through sound barrier while central parts are still subsonic. Resulting shock wave will have destructive effects, if the propeller isn't designed to counter it :)

    I believe it is possible to break sound barrier with ordinary propeller powered aircraft, but propeller wouldn't survive it.
     
  14. RolandGarros

    RolandGarros Well-Known Member

    Joined:
    Mar 21, 2003
    Messages:
    2,867
    Last edited: Aug 1, 2003
  15. -haupt

    -haupt Well-Known Member

    Joined:
    May 24, 2002
    Messages:
    1,165
    Location:
    Brasil
    The same way they do about who was the first man and aircraft heavier than air to fly.

    Wright bros claim they flew in december 17 of 1903. Their plane could not take off by its own ways so it was catapulted. This flight was never officialy confirmed.

    Like Wright Bros there are many other who claim they flew first like the french Clement Ader (1890), russian Nikolas Jonkovski,
    German Karl Jatho (1903), english Sir Hiram Stevens Maxim (1894).
    But those are all just claims.


    Santos Dumont flew officialy the first flight of an aircraft havier than air by its own ways: take off using its engine, fly and land. The first truely modern aircraft, father of the aviation that we have nowadays.

    Or do you see Spitfires and Bf109s being catapulted from airfields during WW2???? Boeings and Tupolevs being catapulted from airports? :deal:

    Wright Bros only appeared with an aircraft capable of taking of by its own ways in 1908, 2 years later.
    We must admit that american propaganda is great, sometimes dirty. Taking away the credits from the real developers and stealing it to themselves to promote their men and their country is a crime.

    Dont get my comment as anti-american. Im not. How could i be anti-american if my favourites musical styles were born there? I love Rock'n Roll that was born in USA (thanks Elvis!), i love the Blues that was born in USA and jazz too. My favourite aerobatic biplane, the Pitts was born there too. ;)

    I just believe that the faults must be addressed, everyones faults no matter who and where.




    ps: rock'n roll and blues may have born in USA but the best band ever is english: Pink Floyd!
    The best looking fighter of all the time: Spitfire!
    :super:
     
    Last edited: Aug 1, 2003
  16. Jacobe

    Jacobe Well-Known Member

    Joined:
    Jan 28, 2002
    Messages:
    3,340
    Location:
    Suomi,Finland
    I've seen Pitt's but not biplane...u got pic?
     
  17. -haupt

    -haupt Well-Known Member

    Joined:
    May 24, 2002
    Messages:
    1,165
    Location:
    Brasil
    [​IMG]
     
  18. Jacobe

    Jacobe Well-Known Member

    Joined:
    Jan 28, 2002
    Messages:
    3,340
    Location:
    Suomi,Finland
    Uh oh....goddamage bad memory ...what the aerobatic plane was what i was remembering....aahh ,Sukhoi :)

    The pitts is a real beaty!!! There was father and son flying those red babies in Finland when I was a kid ,went too see them once ...njam :)

    Sukhoi 26

    [​IMG]
     
  19. Kutya

    Kutya Banned

    Joined:
    Oct 30, 2001
    Messages:
    1,713
    Location:
    Hungary
    That's ZoltŠ±n Veres, Hungarian pilot in his old plane. The new one is a custom built Pitts, with the Sukhoi's M-14P radial engine. Too bad I didn't find any pictures of that beast though I've seen some in the magazines, but unfortunately I don't have scanner...
     
  20. --stec

    --stec Well-Known Member

    Joined:
    Dec 24, 2000
    Messages:
    1,944
    Location:
    Poznan, Poland
    A little correction: British got decrypted Enigma from Polish mathematicians yet before the war.
    Unfortunately after war when Poland was incorporated into the soviet block it became popular in Britain to deny and forget about Polish achievements and our share in allied victory.
     
    Last edited: Aug 1, 2003