Me 262 Air/Speed brakes

Discussion in 'Other Mechanical Systems Tech.' started by Gixxerman, Oct 14, 2011.

  1. Gixxerman

    Gixxerman Member

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    I sometimes wonder about one of the big problem issues the early jet fighters had, the great speed differential being very obvious - particularly for the less than expert pilots expected to fly them.
    Why no air brakes?

    They are very common now but I have never seen any indication that anyone gave them much thought back then.
    Imagine my surprise when I discovered them being used as early as 1931!

    As part of a 'what if....?' how much more deadly would the German jets - assuming the He 162 the rest could have gotten them too - have been had they developed some sort of simple (?) form of speed brakes for them?
    If anyone had experience of such things it was the Germans with their diving mania -dive brakes are surely just another air brake used in a slightly different context?
    The Do 217 tail brake seems to be not too removed from 2 hydraulically opening fuselage 'doors' (รก la F86 Sabre).

    I've seen all sorts of developmental ideas for the Me 262 - the HGIII stage III is pretty radical but even that does not seem to have any thought to the matter (and it was projected to be even faster than the 262.....and by some margin).
    Was the speed brake (like the tricycle landing gear) disdained as a radical American idea Germany had little or no use for?
    Why no speed brakes when the planes were crying out for them?

    Your thoughts gentlemen....
     
  2. tyrodtom

    tyrodtom Well-Known Member

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    #2 tyrodtom, Oct 14, 2011
    Last edited: Oct 14, 2011
    The earliest use I can see of speedbrakes on jets is the FJ-1 Fury, the straight winged sort of predesessor of the F-86. It first flew in 1946.

    The Germans did get on the tricycle gear bandwagon a little late, but for the fields they usually had to use a tricycle gear would not have done the job.

    It's always been a mystery to me why the first models of the Me-262 were tail draggers. What were they thinking? The first flights under jet power, the pilot had to jab the brakes during the takeoff run to get the tail up.
     
  3. post76

    post76 Member

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    #3 post76, Oct 15, 2011
    Last edited: Oct 15, 2011
    Sometimes i think its easier to look back at certain innovations with our modern day hindsite thinking that it would be a needed capability.
    But then, flying was only a couple decades old and jet flight was just ramping up.
    I've also seen some of the tech advances from the Germans out of WW1, thinking wow, they had that back then, but not really seeing the idea refurbished or expanded upon during the second war.
    dive flaps or airbrakes being one of those.
    War also tends to speed projects along if they wanted to see a plane fly before bombs fell on it.
     
  4. Edgar Brooks

    Edgar Brooks Active Member

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    You're a little out, on that; the Meteor I didn't have airbrakes, but they were fitted to the Meteor III, which entered service in January 1945.
    I'd say that it was felt that the early under-powered, 262s needed as great an angle of attack as possible, to get sufficient lift before they ran out of runway.
    Edgar
     
  5. Siegfried

    Siegfried Banned

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    Both the Meteor and P-80A had speed brakes, the Me 262 did not. So although the Me 262 had a higher Mach limit, it would have been somewhat difficult to exploit it fully.

    The Me 410 of course had well integrated dive brakes in the wings so Messerschmitt could surely have done something similar on the Me 262; perhaps only on a smaller scale.

    In a tail attack on a slow moving bomber the tactical solution was an approach from below with a sudden pull up to wash of speed.

    Attacks were likely to have been via the Askania EZ-42 or EZ-45 lead-computing gunsight linked into the FuG 248 "Eule" (also called Pauke SD) ranging radar for aiming of both guns and missiles and possibly for setting of the timed fuses of the R100BS and R100 missile; with this sophistication slowing down to aim would not be important and air brakes would have been less useful. (The Germans did have gyro sights in service and trialed the EZ-40 not to long after the RAF). About 1000 EZ-42 saw service on Fw 190D9, Ta 152, Me 262 and apparently some Me 109K-4 (controversial perhaps).

    The radar ranging Pauke series had been trialed for server years and were being held back for deployment in numbers. FuG 248 was a 10GHz (sub 3cm) device seems to have used a small funnel shaped aerial and I see no issue with it fitting into the He 162 as well as the Me 262.



    For bombing attacks the TSA-2D slide bombing sight was available: in this the pilot aimed his bombs in a shallow dive at the target as if strafing. The sight took in data from either barometric altimeter or the FuG 101a radar altimeter and other sensors such as pitot static and gyro. After the sight's computer had acquired the target the parameters were locked in, a buzzer sounded and the pilot pulled up. During the pull-up an pendulous accelerometer kept track of the aircraft. At the appropriate point of the pull-up the bomb was automatically released.

    In reality with these two sights the Luftwaffe had no great need for air brakes. In fact it didn't need multi-engine bombers much either; a few jets level bombers would do.

    Both the EZ-42 and the TSA-2D saw combat use (with TSA-2D KG-51 on Me 262). The accuracy on the jets was better than on the FW-190 because the potentiometer on the pendulous accelerometer picked up the engine vibration; nevertheless the ground attack FW-190D-13 versions were to get this bomb-sight along with wing fuel tanks for extra range.

    The Luftwaffe's fighter beyond the Me 262 was meant to be either Messerschmitt P.1112, P.1101 or Focke-Wulf TA-183 or Blohm and Voss BV.215. I don't know if these had dive brakes.
     
  6. Ratsel

    Ratsel Banned

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    Wasn't the first Me262 prototypes were based on the 109, or at least used many parts from the 109? I think thats why some of the first ones were taildraggers. I could be wrong however.

    As far as a lack of speed brakes.. perhaps an oversight of the designers?
     
  7. tyrodtom

    tyrodtom Well-Known Member

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    I never seen one picture where any of the ME-262 used any Me-109 components. Even it's first flight with a piston engine wasn't a Me-109 engine, it was a Jumo 210.
     
  8. Ratsel

    Ratsel Banned

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    I'll find a photo for yah.. just give me a few...
     
  9. Ratsel

    Ratsel Banned

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    haha your right..

    v2me.jpg

    maybe I just though the center section of the canopy looked like a 109.. my appologies.

    heres a wild one:

    me262-0035.jpg
     
  10. Gixxerman

    Gixxerman Member

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    #10 Gixxerman, Oct 16, 2011
    Last edited: Oct 16, 2011
    Some very interesting replies there guys, thanks.

    @ Ratsel

    Maybe you've seen the sketches for a cheapo 262 Messerschmitt were working on?
    I've seen Me 109TL mentioned as a designation but I'm not sure if that's accurate.
    It really was much like an Me 109 with 2 jets out on the wings like a 262.

    3bm109tl.jpg

    Luft '46 (yes yes yes, I know) reckon that there were so many modifactions required that it was turning into a new airframe anyways and so there was little to be saved taking that route and decided to press on with the purpose designed plane than start with a modification.
     
  11. Ratsel

    Ratsel Banned

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  12. tyrodtom

    tyrodtom Well-Known Member

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    #12 tyrodtom, Oct 16, 2011
    Last edited: Oct 16, 2011
    " Estimated " performance is always better isn't it .
     
  13. vanir

    vanir Banned

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    The book Test Pilots goes into detail about interwar, wartime and postwar flight testing of front line prototypes (starts with the P-36 and F2F and goes from there). The most striking point was that authorities didn't know about unsafe diving speeds, aircraft in the mid-30s could be put routinely in power-on near vertical dives and in fact this was a military requirement of both Army and Navy contracts, until the P-36 which signalled the end of that era. Every aircraft had to report dive speed with a minimum of two minutes or 10,000 feet at full power and near vertical, by the P-36 they were passing 450mph doing this and it was getting too dangerous. Corsairs and P-38 prototypes were having compressability issues trying it, and nearly killed their pilots.

    So the thing about speed brakes in the early war years isn't really about limiting dive speed, airframes did that for you because they weren't as clean as late war planes. It was just about having a 400mph dive speed instead of a 500mph one in a bomb laden stuka run. I'd say the various national authorities never really thought that hard about limiting dive speed until aircraft like the Corsair were being tested. Even with the P-47C when Lindberg reported to Army Air that it had dangerous dive speeds their approach wasn't to ask for speed limiting dive brakes, instead they asked for the potential of structural failure to be solved, but to retain the higher dive speeds.
     
  14. GrauGeist

    GrauGeist Well-Known Member

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    Messerschmitt was very specific about a speed limit on the Me262's dive, since the 262 could gain speed quickly and suffer control surface "freeze" and/or compromise it's structural integrity
     
  15. Njaco

    Njaco The Pop-Tart Whisperer
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  16. Rivet

    Rivet Member

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    Speed brakes became an active area of aerodynamic research in the Luftwaffe after the initial CIC, Wever, dying in an aborted take off of his He-70 and the succeeding CIC, Kesselring, assuming the formation of the Luftwaffe. The importance of all aircraft accepted as bomber, save for the dedicated horoziontal 111, meant the airframe must have the ability to deliver stores in some manner of diving flight. DVL, the research arm, formed it's own laboratory dedicated to the solution of problems, becoming a massive effort as the entity expanded its own research facility in Vienna after the Anschluss, and the projected speed of delivery increased.

    Regarding the lack of speed brakes in the Messerschmitt 262. Yes, the 262 possessed one aerodynamic control which served as a brake, that of the moving tail. Rapid use of the tail served to adjust the line of flight relative to motion in order to utilize drag as a limiting mechanism. The mention of use of the automatic stores release mechanism in a post above should have this included in data.

    Most of the larger bomber aircraft controls were body-panel foils included in aircraft as large as the Heinkel 177. Regards
     
  17. Gixxerman

    Gixxerman Member

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    Interesting Rivet.
    I must admit I always thought the variable incidence tail-planes was purely a trimming device albeit a major trimming device, as stores or armament was used or fuel was used up the CoG changed during flight.

    I had seen the Hans Guido Mutke claims before but always assumed that his success in slowing the plane down using the tail that way was one of last-ditch desperation rather than it being an accepted known method of dumping excess speed?

    (personally I do not believe the story, I think a 262 would break up long before it got to mach 0.95.....as many have said his story does fit in very well with a craft experiencing the severe troubles non-supersonic aircraft get into as they approach and exceed their mach limit, but which is still well before mach 1)
     
  18. tyrodtom

    tyrodtom Well-Known Member

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    I've read Mutke's account too. I took it to mean he used the trim to pull out of the dive, because his elevators were rigid. Pulling out of the dive slowed the aircraft down. Not the trim slowed the aircraft down, then he pulled out of the dive.
     
  19. Siegfried

    Siegfried Banned

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    #19 Siegfried, Oct 20, 2011
    Last edited: Oct 20, 2011
    The speed of sound at 36,000ft is 660mph, at sea level it is 750mph. Sooner or latter the air thickens, the aircraft may slows down and the mach limit of course goes up so that the mach tuck disappears.

    Modern aircraft still have mach tuck, they simply have minimized it through sweep or thing wing sections and have the flight control system trim it out.

    The Me 262 had quite a thin wing section and that 18 degree sweep would have raised critical mach up to 5%.

    I believe the all trimming tail plane had a too weak electric motor.

    One problem with using such an all trimming system is that when the mach tuck disappears the aircraft may be pulling out with very high g, I believe this is why the P-38 disintegrated during dive tests.

    The British solution on the Miles M.52 was simply to move the whole tail surface.

    The Germans were inclined to use wing sweep to maintain subsonic conditions and behaviour, use elevons (Focke Wulf TA 183, Messerschmitt P.1112), with a t-tail out of the slip stream only for trimming.
     
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