Lockheed P-80 Shooting Star vs. de Havilland Vampire

Discussion in 'Aviation' started by gjs238, Sep 18, 2014.

  1. gjs238

    gjs238 Well-Known Member

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    It would seem that de Havilland had the benefit of actually having a Halford H-1 B turbojet to work with while Lockheed had only blueprint dimensions from which to design the P-80 around.

    For the sake of the war effort, would it have been more practical or more effective to concentrate development at de Havilland, and/or have Lockheed build Vampires under license?
     
  2. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    No. The P-80 in it's original form had a lot of potential and growth. Although the Vampire eventually grew as well, the later models were eventually redesigned airframes. In the bigger picture the DoD and MoD had different visions for each aircraft, especially when planning for the post war years.

    IMO, the P-80 by late 1945 was by far the better aircraft.
     
  3. Koopernic

    Koopernic Active Member

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    #3 Koopernic, Sep 19, 2014
    Last edited: Sep 19, 2014
    I can just imagine the not so likely memorandum:

    From: Henry H Arnold, General of the Air force, United States Army Air forces.
    To: Kelly Johnson, Lockheed Long Beach, California.

    Dear Kelly, False alarm. We won't be needing your help on the jet aircraft after all. The Brits have got it all under control. As we won't be needing the P-38K either you can take a long break. I hear the weather is good down there, enjoy
    .
    :)


    All jesting aside, the USA had a superfluity of engineers. They could be asked to a/ sit aside and do nothing. b/ develop something not quite so useful, such as a Beechcraft Grizzly or c/ work on advanced types.

    The Vampire was a good aircraft, more manoeuvrable than the Meteor and about the same speed but I believe it had less growth potential and a lower Mach limit.
    Would it be any good against advanced types such as the Arado 234C which when hauling a large bomb load was likely to be capable of moving 540 mph or so. (A couple did fly at the Luftwaffe test centre). Was the vampire up to it?

    The Welland/Derwent II jets on the Meteor was so small a two engine aircraft was required. Because these engines used centrifugal compressors their relatively large diameter caused issues with drag, shock drag and other airframe integration issues. The solution, which took a long time and I think 3 versions of the Meteor was extended nacelles to increase their fineness and reduce shockwave issues. The length and diameter of these as well as their long duct lengths must have added much weight, so much I suspect any weight advantage the Derwent had over the Jumo 004 would have been lost in the ducting.

    Thus early centrifugal were better adapted to single engine aircraft where the bulk would be absorbed by the fuselage. I would say that DeHaviland was trying to minimise the complication of long hot ducts in that twin boom design. There was the nene already on the bench but too late to help vampire and meteor development.

    The USA was not as backward as some might think, Back in the 1930’s the engineer Nathan C. Price began work on what would be the Lockheed L-1000 (latter ran in 1942 as the J-37) turbojet. In 1941 Kelly Johnson ordered development of the L133 supersonic fighter proposal which used this engine and canard technology to avoid shock interference with the tail plane. Someone at Air Material Command was not so excited and development proceeded slowly but it did put Lockheed in the good books.

    When Happ Arnold found out about the British work he promoted what would become the Bell XP-59. Unfortunately its antiquated wing section meant it could not exceed the speed of contemporaneous piston fighters.

    No one had involved the NACA, for what ever reason.

    At the NACA was a man known as Eastman Jacobs. He had developed the NACA 4 digit air foils used in the Spitfire and P-40, the 5 digit air foils used in the Hellcat, Corsair, Fw 190, Lancaster and the Laminar flow wing used in the Mustang.

    Jacobs was developing a “550 mph” aircraft known as “Jakes Jeep” which used the NACA laminar flow wings which had a very high Mach limit by powering it with a motorjet. A motorjet functions like a turbojet only the compressor is not driven by a exhaust gas turbine but a piston engine. The Italians had tried this type of engine in 1941 in the Caproni Campini N.1 but its low powered Isotta Fraschini engine lacked a supercharger so it lost power extremely rapidly at altitude.

    It produced about 1550lbs thrust from 850hp. Jakes Jeep would have been turbocharged and had a more powerful engine. Imagine this was a two stage Merlin or turbo R-2800.
    So, had the USAF or Bell talked to NACA the laminar flow technology they had developed and that worked perfectly in the P-51 might have made the P-59 the first effective Jet fighter of WW2 rather than just a testbed.
     
  4. Shortround6

    Shortround6 Well-Known Member

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    Some sources for the Arado 234C say 540mph with 1/2 fuel and no bomb load.

    Ducts are probably not as heavy as engines, all things considered.

    The Lockheed L-1000 (J-37) was a vastly over-complicated dream that would only see comparable engines 12-20 years later. NO amount of funding in WW II would have seen it turned into usable hardware. The first one didn't even run until 1946, not 1942.

    The Isotta Fraschini engine, IF it was the Isotta Fraschini L.121 RC.40, sometimes reported, had a supercharger. Just a single stage one but the critical altitude was 4000 meters. That is what the "RC.40" means. On Italian engines the RC is followed by a two digit number and those two digits are the critical altitude in hundreds of meters as in Fiat A.74 R.C.38 used in Macchi 200. Critical altitude in 3800 meters.
    The motorjet sounds a lot better in theory than it it ever turned out in practice. Some those early turbo jets actually used several thousand HP to drive the compressor. So a motorjet equivalent to a 2-3000lb thrust turbojet would weigh quite bit more.
     
  5. davebender

    davebender Well-Known Member

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    Both were too late for WWII. Are you referring to the Korean War?
     
  6. Koopernic

    Koopernic Active Member

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    #6 Koopernic, Sep 20, 2014
    Last edited: Sep 20, 2014
    The quad engine Arado 234C was initially Mach limited not thrust limited. The Mach limit showed up as tail plane flutter at 528mph-532mph. The cause was a supersonic flow established between the engine nacelles and the fuselage.

    Hence the Arado 234C could exceed its own Mach limit in level flight if the engines were set to full power. This means test conditions, such as 50% fuel load you mention above, do not effect maximum speed since the throttles can simply be increased slightly. Obviously if the Arado 234C3 was slowed down by carriage of external bombs it could compensate simply by increasing thrust.

    This mach limitation was raised slightly be re-profiling the nacelles which raised the Mach limited speed to 555mph-560mph.

    The Ar 234C was scheduled to receive the 900kP thrust BMW 003C but initially received the 800kP BMW 003A2 although the aircraft was still Mach limited. The BMW 003C had the same hot section but had a new 50% reaction compressor of higher efficiency and flow, in fact it had two: one developed at Brown Boverie and Cie and another at BMW and the DVL to choose from.

    A swept wing had been developed and was in the process of being mated with then fuselage when British troops over ran Arado, in fact it was a scimitar or crescent wing, had been chosen as it overcame both span wise flow issues and didn't required new wing mounting points or center of gravity adjustments.

    Bottom line this aircraft, likely the fastest of the war (the other contender being the He 162) was beyond any future Vampire's speed clean and certainly beyond the vampire of 1945 with bombs.

    I do not share your pessimism in regard to the motor jet. The Campini's primitive implementation and unimpressive performance rather than being a proof of concept acted more as a proof of failure and entered the 'folklore'

    The low pressure and exhaust velocity meant it was more like a ducted fan with some burners to warm the air a little as an afterthought. Eastman Jacobs had built a 14 stage compressor indicating he was looking at pressure ratios of around 8:1 and that this would be a real 'reaction engine' rather than a warmed up ducted fan.

    I take your notes on board regarding the campinis supercharger but not that its low power (670hp) and low full throttle height (4000m or about 13200ft) are unimpressive. Put in a 1700hp merlin or a turbo charged radial with two stages and 300lbs jet thrust that is able to maintain say 1450hp to about 22000ft then thrust is much more impressive, especially as unlike a jet the motorjet would not loose much power/thrust at altitude.

    I think Eastman Jobs was disgracefully treated by his country: this ingenious man who had made possible the P-51, moreso than anyone at North American because he developed not only laminar profile wings but the computational methods to ensure they have good stall and pitch characteristics was kept out of the loop on jet development and not invoved with the XP-59, which he could have made a success. It's no surprise he retired early in 1944 and opened a restaurant. Most other attempts at laminar flow wings were failures (that of Spitfire variants dubious, Tempest V unpleasant, Me 309 we don't know, Russians seem to have run experiments in 1944 that needed slats)

    It's also worth noting that well built examples of the Me 262 could sustain a level speed performance of 560mph and there were thrust and subtle Mach Limit increases being developed:

    A strike package of Ar 234C and Me 262 would simply outrun any vampire built. AFAIKT the P-80A had a higher Mach limit and of course developed into a larger more powerfull aircraft when it abandoned the Goblin as undersized. The External Cowling of the Me 262 was nearly 100kg, that of the Meteor must have had twice the area and material, plus to that we can add extensive hot exhaust ducting. Say 250kg extra.


    Me262AreaRule.jpg
     
  7. davparlr

    davparlr Well-Known Member

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    It appears that the 234 does not have an internal bomb bay which means it would be unable to obtain these speeds prior to weapon delivery. And it is doubtful if these changes were ever made but was probably proposed.

    I believe these were proposed upgrades. I could find no indication this engine was ever run.

    There is no doubt that the Germans had a decent lead in advanced aerodynamics such as swept wing. However, the allies could quickly recover and had more powerful engines to use. Both the Americans and British had 4000 lb thrust engines starting production, with the 5000 lb thrust Nene right around the corner. The largest German engine that had run was not over 3000 lb thrust.
    It takes a large amount of power to drive the compressors for jet engines. It took 4000 hp to drive the compressor of the Derwent engine to 16k RPM. One manufacturer had to get a steam turbine off a warship to test one of its compressor designs.

    I didn’t know that. Thanks for the information.

    I have found no source that shows a Me 262 going faster than about 540 mph except one showing proposed design cleanups. This is similar to the top speed of the P-80 and Vampire. The Meteor was slower. There is a proposal for afterburning but was never developed that showed a significant increase in airspeed

    Probably not true with bombs.

    This appears more to show a streamlining effect rather than Area Rule. Area Rule would require a reduction in cross sectional area in the wing area, not the addition of a hump.



    Not with bombs.
     
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  8. parsifal

    parsifal Well-Known Member

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    According to Green ( a not very good source), the AR 234C-1 specification were as follows 515 mph without bombs and half fuel at sea level. and 542 mph at 19K with the same loadout. With the HS 294 attached, the aircraft attained 470 mph at sea level and 510 mph at 25K altitude.

    The De Havilland Vampire FB5, introduced early 1947 and one of the main types had a top speed with full fuel and gun load out (but no external stores) of 570 mph at 20K. The Venom FB1 was developed from the Vampire FN8 and introduced in 1950, with Ghost engines. it had a top speed of 640 mph at 20K with full fuel and gun load out, but no external stores. This was the single seat verasio. the two seat FAW21 introduced 1954 with limited all weather capability, but two seats which slightly affected performance.

    Against even a half loaded AR 234C, kitted out for recon only, the Vampire had a comfortable margin of superiority in terms of its top speed. There were so few F1s introduced as to not matter. .
     
  9. Shortround6

    Shortround6 Well-Known Member

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    The need for even more power than could be supplied by a single piston engine to power a jet engine compressor of rather modest size has already been mentioned. And there is no magic that allows you to compress the same volume air twice as much (8:1 ratio vs 4:1 in the Derwent) using less power no matter how high tech a design compressor you use. The Derwent compressor was over 70% efficient.

    Now lets look at a few of the practical problems, like larger diameter fuselage for the moterjet vs a piston engine aircraft to accommodate the duct. More skin friction and larger cross section means more drag and no, subtracting the area of the duct from the frontal area doesn't work real well, you also have the drag from the interior of the duct. Larger structure means more weight, especially in any areas subject to the higher pressure after the compressor section.
    You then have the very practical problem that the piston engine used to power the compressor weighs much more than any early jet engine, Early Derwent was under 1000lbs compared to your suggested 1800-2200lb powerplants (two stage Merlin plus radiators and coolant? or big radial?)

    Eastman Jacobs may have designed or even built a 14 stage axial compressor which may very well indicate the pressure ratio he was looking for. The big questions are did he actually achieve that goal and and what mass airflow and what weight and what efficiency? Quite a number of people were working on axial compressors and trying for high compression ratios and failing to reach them for quite a number of years.

    I would note that the GE TG-100 turbo prop engine used a 14 stage compressor and got a 5.5:1 ratio. The Amstrong Siddeley Python turbo prop used a 14 stage compressor and got 5.0:1. The Bristol Theseus used and 8 stage axial feeding a single centrfugal compressor and got 4.35:1 all by 1947.




    Strange, the modern built examples are placarded at 540mph, above that and you are a test pilot.
     
  10. tomo pauk

    tomo pauk Creator of Interesting Threads

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    I'm not sure from where you've pulled this (bolded part).
    The Spiteful (guess that is what you mean by Spitfire variant?) also featured a reduced wing area compared with Spitfire, despite having the heavy Griffon on board, along with 4 cannon armament (and 600+ rounds) and later addition of the rear fuselage tank that increased fuel tankage to 178 imp gals. No wonder the handling got far worse than Spitfire's.
    The Tempest's wing was anything but 'unpleasant', both in looks and flight behaviour. We can remember that basically the same wing was successfully used on a naval fighter, not something the P-51 could do well.
    Me-309 - attempt to put too much of heavy stuff (engine, armament package, maybe even fuel) on a small wing, similarly sized to that of Bf-109. For a reality check - let's try to install the DB-603, 3 cannons and 4 HMGs on the Bf-109? Not going to work.
    Soviets used the laminar flow wing on the La-9, we don't know how much of development was their, and how much they used foreign knowledge.
     
  11. awack

    awack Member

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    The 542mph of the 262 is as far as i know an average of i think 120 jets tested in dec 44, sea level was 518/519 mph..post war testing against the 262 mentions the 262 achieving 568 mph at 20200 ft true air speed in the US...Eric brown of course mentions the 262 achieving 568 mph during UK test.

    I guess the only standard production aircraft in the world that could catch the Ar 234c(recon mission) was the 262....as far as p80 vs vampire 1, the p80 had better performance but i believe the vampire was overall more Maneuverable.
     
  12. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    I think you'll find this depended on speed and altitude. The F.1 Vampire was docile but gutless at altitude. Although the P-80 was heavier, it was putting out about 1000 pounds more thrust.
     
  13. awack

    awack Member

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    I didnt know about the vampires lack of high altitude capability, this would be important since allot of combat was taking place from 18000 too 30000 ft, hell, ive read p51 pilots speaking of 262s coming in on the bomber formation at over 40000 ft, and that the jets were above their own operating ceiling, i knew that it could fly over 40000 ft depending on load out, but not that high.
     
  14. Koopernic

    Koopernic Active Member

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    #14 Koopernic, Sep 23, 2014
    Last edited: Sep 24, 2014
    In terms of speed: please find a photo of Walter J Boyne's book "The Best of Wings". He quotes program test Gerd Lindner pilot as saying it could achieve 565mph at 16,400ft (that would have been 925kmh at 5000m). He was a professional test pilot, not a factory acceptance pilot or a fighter pilot. He's paid to be technically accurate. Smooth surface, maybe filled in, well aligned airframe, well aligned engines, good pair of engines.

    Lindner also notes he nursed a pair of engines to 60 hours on the wing. The official Jumo MTBO was 25 hours and on the basis of spare parts production the Germans expected 4 x 25 hours life out of the engines. The Luftwaffe maintenance crews, the blackbirds were possibly pulling them early. It is also important to note that the hollow air-cooled blades of the Jumo 004B4 only reached the front in November 1944 or so and so air cooled blades were likely quite rare.

    Vampire Performance Trials
    Meteor Performance Trials
    P-80 Performance Tests

    Note these are mostly post war tests. Meteor had 4 engines Welland (two ratings), Derwent I, Derwent II (two ratings) and finally Derwent V which was a scaled down Nene that only saw service in 1948 on the Meteor F4 though it was flight testing in 1945 and broke some sea level speed records (where Mach wasn't an issue)

    Note the Faster P-80's of 1947 fame received clipped wings and modified nosese to increase speed. P-80B added ejection, P-80C much improved.


    Boyne_Me262.JPG
    The fuel control system of the Jumo 004B was as follows
    1 Gear driven pump set to supply slightly more fuel than would be needed at sea level full thrust.
    2 Pressure relief regulating valve converts this to a constant pressure.
    3 Pilots throttle open a valve whose degree of opening determines fuel flow rate: this spools up the compressor.
    4 Between the pressure valve and the throttle was also a centrifugal governor, also set by the pilots throttle, that regulated the engine RPM.

    An exhaust cone acted as a variable area nozzle in response to engine back pressure, it should have helped regulate air fuel ratio a little but didn't help much.

    April should have seen the deployment of the 'beschleunigungs ventil' or 'accelerator control valve' that measured the air flow rate and adjusted the fuel in proportion to it so that rapid throttle movement by the pilot wouldn't flame out or burnout the engine when it was accelerating. Come back in a few days and I will post a link to proof of this device.

    The Jumo 004B couldn't get much above 38000ft because the compressor could surge, the cure was reducing RPM below the critical speed of 8700 rpm which of course would reduce thrust. At low fuel flow rates during low thrust or idle or at above 38000ft the fuel flow rate was so low the nozzles could not provide the correct vaporisation which could flame out the engines. The 'cure' was to be duplex nozzles from the L'Orange company (Oscar L'Orange was a colleague of Robert Bosch). Duplex nozzles switch to a second set of nozzles at low flow rates set to provide a better spray/vaporisation pattern.

    There was a new unrestricted RPM compressor under development which might have seen instalment in the Jumo 004D at the end of the war, Nowara says these engines, without RPM restriction, were starting production but not seem to have been found but were supposedly rated at up to 1100kP (instead of just 880kP) There was also a Jumo 004C good for about 950-1000kP.

    These engines are somewhat of a mystery though.

    Either way the accelerator valve and duplex nozzles would have added greatly to Jumo 004 handling and reliability even though compressor RPM couldn't be raised.

    Arado 234C3 is quoted as capable of 560mph specifically with BMW 003A1 engines in David Myhra's book "Arado 234C" its a rather large 450 page tome with pictures of David visiting with Rudiger Kosin the designer. It's possible this is the estimated speed with the BMW 003C but I doubt it as Myhra is at pains to list details on a doxen different variants,. There was a lot of thrust here 4 x 800kg = 3200kg/7240lbs. By far the most powerful WW2 jet by far.

    The bombs were carried semi recessed beneath the fuselage and engines. A bomb as big as 2000kg could be lifted. Given the high speed and high power it wasn't going to slow too much. William Green's book quotes 515mph with a Hs 293 or 294 glide bomb, a rather ungainly winged and rocket boosted device.

    The BMW 003C was never built but the compressors had been built and benched, the hot section was the same. The BMW 003E of He 162 was the same as BMW 003A apart from the accessories gearbox and had a 900kg overload thrust emergency rating for 30 seconds. Probably most useful in take-off and a quick acceleration to operating speed.

    I doubt any WW2 allied jet exceeded 500mph during WW2, the meteor was at either 466mph or 482 at the end of WW2, it reached 495 and finally 515 at the end of 1945.

    The speeds are well covered in ww2 performance testing: I'll link to it at the end of my image.

    Tempest V stalled without warning or buffet and flipped to opposite bank. Unpleasant.

    P-51H was considered suitable for carrier use, due to the longer tail. The wings on the P-51 were always good.
     
  15. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    #15 FLYBOYJ, Sep 23, 2014
    Last edited: Sep 23, 2014
    The first P-80A was delivered in January of 1945. the first models were grey and they had all structural seams filled in. The "Grey Ghost" was a specially modified P-80 used for speed records. Later P-80As were delivered unpainted. They had a top speed of over 550 mph and I'm sure were flown that fast during acceptance flights.

    EDIT

    "The first flight of the XP-80 took place on January 8, 1944 with test pilot Milo Burcham at the controls. The first flight had to be cut short after only five minutes because of undercarriage retraction failure and the pilot's concern over boosted aileron sensitivity. These problems were quickly fixed. Subsequent test flights reached a top speed of 502 mph at 20,480 feet, the XP-80 becoming the first USAAF aircraft to exceed 500 mph in level flight."

    Lockheed XP-80 Shooting Star
     
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  16. Koopernic

    Koopernic Active Member

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    #16 Koopernic, Sep 24, 2014
    Last edited: Sep 24, 2014
    I agree, I had read J Baughers page and it was why I regarded the P-80 superior in speed to the Vampire. Vampire Mach limit was 0.76 that of the P-80 somewhat higher. I think initially 0.78 but it was controllable to 0.85. Depends on version, I think nose was profiled and maybe something called a "compression strip added"

    The designers of the Me 262 did a very good job, to be frank however they would need to have made improvements by the end of 1945 since by any speed advantage over the P-80 would be gone or minimal. Speed brakes would need adding in particular since the P-80 could go to the mach limit and a little beyond and safely recover.

    The Germans were definitely ahead in supersonics with an appreciation of both wing sweep and the area rule. It is a matter of conjecture as to whether they could get enough thrust out of their engines to exploit this. The crescent wing Ar 234 almost certainly would have been the first operational swept wing aircraft.
     
  17. davparlr

    davparlr Well-Known Member

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    It should be noted that the XP-80 only had 2460 lbs of installed thrust, or only 62% of the thrust of the Me 262 and still did over 500 mph. The P-80A was a larger aircraft and heavier. This is impressive, especially compared to the P-59 and the FH-1.
     
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