A Flawed Strategy: German Fighter Jet Doctrine

Discussion in 'Aviation' started by SpicyJuan11, Jul 8, 2015.

  1. SpicyJuan11

    SpicyJuan11 Member

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    Hello, I was wondering, did the German's get it right with developing fighter jets for the Zerstörer role? Or would it have been better to develop them as air-superiority fighters a-la He 280?
     
  2. davebender

    davebender Well-Known Member

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    German jets did not enter combat in quantity prior to March 1945. That's too late to matter no matter what strategy is employed.
     
  3. kool kitty89

    kool kitty89 Well-Known Member

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    The He 280 might have been more to the Me 262 what the Bf 109 was to the Fw 190. Not necessarily a better air superiority fighter, but somewhat smaller, possibly cheaper, potentially entering production earlier (assuming Heinkel engine development continued, possibly with compromises to push engines into production when marginally ready) while also being shorter ranged, and less heavily armed. (it should have been capable of carrying a pair of MK-108s, possibly 3, in place of the originally planned 3x MG 151s)

    I've argued Heinkel made the mistake of not continuing with the earlier HeS 3 and 6 designs given it took nearly 2 years for the HeS 8 to reach similar performance and stability/reliability while not being unreasonably large in diameter (smaller than Whittle'e engines, but not as compact as the HeS 8). The HeS 30 was an excellent follow-on design to pursue in any case that shouldn't have been cancelled and other than that I'd suggest larger centrifugal engines more in the Goblin's class to be pursued rather than trying to slim down the HeS 3/6 designs. (probably use the combustion chamber and turbine experience gained from the HeS 30 project too) But this is getting more into what's already been discussed in the jet engines threads.


    It was definitely a mistake to cancel Heinkel's engine projects and also a mistake to not concentrate more on defensive weapons projects (like interceptors) more in the early-war period. (that goes for piston engined interceptors and night fighters as well)
     
  4. parsifal

    parsifal Well-Known Member

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    The reliability and serviceability issues were the key issue IMO. Hitlers intervention was a definite backwards step, except that his enthusiasm meant no shortage of funding, albeit for the wrong role. take out the FB role and you lose Hitler's interest, Lose Hitler's interest and you lose some of your funding.

    The failure of the 262 was a reflection in miniature of the wider failure of the german system as a whole
     
  5. GrauGeist

    GrauGeist Well-Known Member

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    The He280 was a smaller airframe than the Me262 and had high praise from pilots who flew it regarding it's performance. Also being armed with 3 MG151/20 gave it quite a punch...why change them out for a pair of lower velocity, shorter ranged weapons? And the limited range of the 280 could have been addressed by either modifying it's internal fuel stores, or by adding drop tanks for extended missions - this last option worked fine for both the Bf109 and Fw190.

    In an alternate scenario, where the RLM saw the future and value of jet flight when the He178 first flew and aggressively supported the jet program, then the He280 could have been the true jet fighter with the Me262 as the heavy interceptor (with the He280 flying top cover). Also, had this occurred earlier in the war's timeline, I would imagine that the jet program would have been a little more organized, developed along more rational lines and all these last minute "wunderwaffe" designs and concepts probably wouldn't have come along. This would include the He162, the Hs132 and such.

    This also means, that had the jet program started in earnest earlier, that the natural progression and development of such designs as the Me P.1101, the Ta183 and the Me262 HG series may have actually seen completion.
     
  6. GregP

    GregP Well-Known Member

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    #6 GregP, Jul 9, 2015
    Last edited: Jul 9, 2015
    They might have gotten the He 162 going sooner.

    That was headed in the right direction, though they'd have had to deal with the straight wing sometime, and they should have gone away from a wooden wing to a metal one. Metal is not glued together and rivets are easy to inspect.

    It might have made some difference had it been avialable in some numbers and had not been susceptible to wood-glue sabotage.

    I belive the Horten flying wing fighter was a mistake and should not have been pursued at the time. Too little chance of it really doing anything. Fighters need to be able to be thrown around the sky and you couldn't DO that with a flying wing at that time with no computer help. It was interesting, to be sure, but accomplished exactly zero for the war effort.
     
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  7. SpicyJuan11

    SpicyJuan11 Member

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    That's true Dave, but I'm still curious.

    Did Germany have the capacity to pursue both axial and centrifugal projects? Could Germany have met or exceeded the Allies in centrifugal jets,

    What system?:lol:

    Yes, I was wondering about that as well. As for the He 162, wasn't it in development before the Volksjäger specifications were given by the RLM?

    Yes, IIRC they did have projects of swept-wing He 162's before the design was completed and I'm sure aluminum would've been used if the situation wasn't that dire. I have to disagree about the Horten's though. They were extremely advanced, and the Horten brothers knew about the troubles without a vertical stabilizer and designed their interceptors/fighters with them.
     
  8. SpicyJuan11

    SpicyJuan11 Member

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    Sorry about that, double post.
     
  9. GrauGeist

    GrauGeist Well-Known Member

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    They manufactured the DB601 at the same time they manufactured the BMW801, didn't they? :lol:

    In otherwords, yes, they could have


    Yes, Heinkel was toying with several lightweight fighter concepts, one of them being the P.1073 which was used as the basis for the He162.
     
  10. SpicyJuan11

    SpicyJuan11 Member

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    But did they have the capacity to mass produce HeS, and Jumo jets along with the DB 6XX series, BMW 801, and Jumo 222? The BMW 802/803 were cancelled to focus on the BMW 003 historically.
     
  11. GrauGeist

    GrauGeist Well-Known Member

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    If the RLM had realized the potential of what they were looking at back in August of 1939, when the He178 flew and prioritized the jet engine program, I am fairly sure that the Hirth engines and the Junkers/BMW engines would have been allotted adequete development/manufacturing...also, this would have been at a time when there wasn't a mad rush with the Reich collapsing.

    It might also be worth pointing out that the He280 was on the drawing board about the time the He178 was making it's powered flights in 1939 and about the same time, Messerschmitt was putting the Me262 idea down on paper.

    The interesting fact, is that the He280 went from paper to powered flight in about a year's time. So again, if the RLM had taken the jet program seriously, then the early part of the war would have seen a whole different aspect of air operations.
     
  12. GregP

    GregP Well-Known Member

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    #12 GregP, Jul 9, 2015
    Last edited: Jul 9, 2015
    The Horten Flying Wing fighter was NEVER going to be a fighter. It could fly fine in more or less straight lines, but was not going to be able to roll or pitch while rolling at the same time quickly or even necessarily under control. You could get it into an unrecoverable spin on one engine, if you got slow and had the operating engine at full power, so something like a vertical reverse was beyond the capabilities of the Horten.

    It might have been fine as a recon platform or a heavy fighter to intercept bombers only, but it was never going to be able to mix it up with single-seat piston fighters in it's wildest dreams. Bombers interceptors were fine in 1943. By late 1944 and into 1945 the ALlies were sending over waves of 1,000 bombers escorted by 500 - 750 fighters, and bomber interceptors had little chance of living against hundreds of slower fighters with guns that were there specifically to defend the bombers. Sure, they'd get a few, but so would the defending fighters, and Germany never DID get many jets into service.

    IIRC Germany made some 1,500 Me 262 airframes but never had more than about 100 in service at any one time. That's according to Adolph Galland after the war. Suppose they had concentrated instead on Hortens. I don't belive the'd have been capable of having more than about 100 in sertvice at any one time since that's the results they achieved in real life when the survival of the country was at stake.

    And if they had concentrated on the bombers only, they might have achieved what the Me 262s did or slightly better, and that wasn't enough to slow down the end of the war in the slightest. Ergo, no difference. And it is also possible the Hortens might not have achieved what the Me 262s did in any case. It might have had some horrible development issue that precluded it from entering service. We don't know since none did and we haven't ever flown one ourselves. At least the Me 262s got into service and proved their concept was sound even if their numbers and trimliness weren't.
     
  13. SpicyJuan11

    SpicyJuan11 Member

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    You're not listening GregP. I agree with your assessment for, and only for the Ho IX/229. The Ho X and other flying wings designed as fighters had a vertical stabilizer.
     
  14. GregP

    GregP Well-Known Member

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    I don't find an Ho X design with a vertical fin, but I agree that if enough vertical surface area were added together with a rudder, then the flying wing becomes MUCH more able to handle yaw. I am still unsure of spin recovery since tghe vertical fin would notbe any appreciable distance from the center of rotation in a spin, but sweeping it aft could fix that.

    Once again, they might have made a few and they might or might not have been in service any sooner or in the numbers that were achieved in real life. I can make an assumption thath they might have been as good as the Me 262 and well might have turned better, but am very unsure if that translates into any significant difference in combat effectiveness. My feeling is no ... that is, not better, but perhaps as good ... but it might have proven better than the Me 262. In the war, the Me 262 proved to be a tough customer and making a sweeping statement that a new untried design would be better than arguably the best combat jet of WWII is brave.
     
  15. GrauGeist

    GrauGeist Well-Known Member

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    No Horten wing, glider or powered, ever incorporated a vertical stabilizer with the exception of the H.IV, which posessed a small dorsal stabilizer.

    Only the H.XIII concept proposed a vertical stabilizer, which also contained the cockpit. It happens that this borrowed from Dr. Lippische's design, the DM1
     
  16. kool kitty89

    kool kitty89 Well-Known Member

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    For different reasons at different times in the war. The BF 109 got plenty of support without being a good fighter-bomber (the He 280 probably could have been adapted to be competent in short-range tactical strike, somewhat akin to the Bf 109 -the Me 262 was better suited more like the Fw 190 -loiter time would be poorer than the 109 though ... a consistent problem with jet vs prop CAS aircraft to this day).

    The main issue wasn't specific to Hitler but the entire doctrine and planning associated with the War ... it was intended to be very short and offensive action centric with little interest in advanced designs that might take a couple years to reach service as well as little interest in defensive weapons aimed at retaining/protecting territory rather than invading/attacking. The final problem was the flawed nature of the original Zerstörer concept that precluded highly streamlined, single seat (or at least optimized for such), high speed heavily armmed fighters without defensive armaments. (they also lost opportunities for some good high performance fighter-bombers there)

    Lack of emphasis on jet engined bombers also seems a bit odd in general given LW doctrine would have favored those as the next generation of high speed light/medium bombers and would lend more credence to the engine technology independent of Fighter aircraft. (do note the He 280 was canceled well after the HeS 8 and 30 engines were halted in favor of the HeS 011 at Schelp's demand -also forced the merging of Heinkel's Centrifugal and Axial projects and emphasized the rather impractical mixed-flow 'diagonal' compressor which was both untested and costly to manufacture compared to the sheet metal bladed centrifugal impellers Ohain was using -much simpler/cheaper than the machined Whittle/Rolls Royce units- and even the precision machined blades of the HeS 30 were a great deal more economical -and efficient- than the diagonal design ... that all aside from that, in hindsight the diagonal compressor proved a failure with little advantage over single centrifugal stages ever achieved in post-war testing)




    I suggest the MK-108 for the same reason it was used on any fighter: bomber destroyer capabilities. The Me 262 likely could have mounted 6 MG 151/20s in place of its MK 108s with similar overall weight (maybe some added drag from the protruding muzzles) but would have had more trade-offs in the bomber destroyer role.

    The main advantage of jets (He 280 included) was the sheer speed and ability to evade enemy fighters and attack their targets ... enemy fighters or bombers alike. (or recon aircraft) A huge chunk of the Me 262's added weight came from its choice of engines which the He 280 fared even worse with (slightly faster than the Me 262 but poor range and loss of its maneuverability advantage). HeS 8 engines would have left the Me 262 a bit underpowered but with a much higher rate of roll while mature HeS 30 engines should have really made the Me 262 superior to a similarly powered He 280. (the 280 might have had an edge in raw speed and climb due to the smaller fuselage, but the gap probably wouldn't be wide enough to nix the advantages of range/endurance and load bearing ability ... still, perhaps enough to merit both designs stayed in production)

    Additionally, if the HeS 8 and HeS 30 had both beat the 003 and 004 to production readiness it might have merited avoiding pressing those latter two into production early as well. (ie only mature 003 and 004 engines with the latter not mass produced until the D model and the former perhaps being foregone in favor of its more powerful reaction-compressor bladed 003D model as well -more in the low 'class 2' thrust range)





    Wood might have been OK early war and Heinkel had been trying to get wooden winged fighters into production since the He 112 (and the He 178 itself used wooden wings) but there's certainly advantages to sticking with all-metal wings as well.

    The He 162 is interesting but getting jet engines reliable and powerful enough for a useful single engine fighter earlier on might have been impractical, especially for a useful bomber-interceptor armament. It might have been worth scaling up the HeS 6 to something more in the Goblin's class and aiming at a single engine fighter (or possibly a single design intended to either use one 'big' centrifugal engine or a pair of slender HeS 30s) but you'd probably end up with a twin-boom arrangement a la Vampire in that case. (maintaining relatively easy access to the engines for maintenance while minimizing intake and exhaust losses)

    The HeS 30 would have been an excellent match for the He 162 but that assumes both good reliability and still doesn't address the armament limitations.





    The centrifugal projects outside of Heinkel/Ohain's work were abandoned early on by the Germans. Ohain mainly used his centrifugal compressor + radial turbine arrangement as a technology demonstrator proof of concept and then expanded it to be a stop-gap development aiming to get mass production engines ASAP. (this fell apart when the compromises in the HeS 8 made to make it smaller in diameter ended up slowing development substantially compared to the preceding HeS 3 and 6 -IMO a very bad trade-off compared to just working with the larger diameter, heavier HeS 6 -approximately 37 inches or 94 cm in diameter and 420 kg, little wider than the HeS 3 as the added thrust was achieved through a broader pitch compressor and longer/deeper diffusor chamber rather than larger diameter impeller/diffusor: also why the compression ratio remained 2.8:1 where larger centrifugal engines normally end up with higher peak compression ratios)

    Ohain never adopted the flame cans or axial turbine used by the parallel Wagner/Muller HeS 30 team. (though his idea for a centrifugal compressor with axial diffusor -as used on the HeS 8- seems far better suited to an axial turbine than the radial ones he was working with and indeed a number of compact post-war centrifugal engines did use axial diffusors -particularly small engines aimed at cruise missle use)

    As above, Heinkel had been attempting to use wooden wings for quite some time (the Gunter Brothers that designed the wings of several Heinkel aircraft were experienced in working with both wood and metal, though the RLM seemed dubious in using a wooden wing on the He 112). Wooden aircraft production only became a serious problem late-war when suitable glues were no longer available. (Focke Wulf also ran into the problem with relative inexperience with wooden aircraft: Gotha, the Horten Brothers, and Gunter Brothers were experienced in wooden aircraft construction -albeit only the former was experienced in mass production of wooden aircraft)
     
  17. kool kitty89

    kool kitty89 Well-Known Member

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    One difference between Heinkel's engines and Jumo's was the prototypes had always stuck with Krupp stainless steels of similar types to what the production 004B used (though I believe with lesser use of ceramic coated mild steel) and thus could have been pressed into mass production early war once at least marginally reliable in the sense the 004B was. (unlike the 004A which used substantial amounts of rarer alloys containing larger portions of nickel and chromium and significant quantities of the much more scarce cobalt and molybdenum -also in short supply for use in the cutting steel of machine tools)

    Nickle wasn't in short supply until late war after losing their supply line to Finland. Chromium was scarce the entire war but more consistently so to the extent of being rarer than Nickel early war but far more available late war than Nickel. (hence the use of nickel-free stainless steel in some 004B models) Regardless, it seems plausible that the HeS 6 refined for mass production (or HeS 8 'frozen' and forced into mass production in 1942) could have been practical to mass produce in terms of metal resources. (also remember that while the HeS 8 may have used a higher percentage of stainless steel in its construction, it was also much lighter than the 004 so the actual per-engine alloy usage wouldn't be as extreme)




    Indeed, any/all funding issues would be more akin to the state of advanced piston engine development around the same time. (do remember the DB 603 was halted for some time and there was inconsistent support for some of the other advanced piston engine designs)

    Some of the BIG advantages Schelp saw in turbine engines was the speed and ease of manufacturing possible with far less machining and casting and far more use of cut/stamped/pressed sheet metal components as well as the potential to use a wider variety of fuels. (but particularly diesel and kerosene)

    The RLM took greater interest in companies other than Heinkel for initial development and Heinkel was left to privately fun development until official support was given in 1941 following the maiden powered flight of the He 280. (per Ernst Udets agreement, Heinkel was thus allowed to merge with Hirth)

    Similar concerns over perceived incompetence of Junkers' airframe team developing their own engines led to the forced merger with the independent Jumo team working on what became the 004. Roughly half of the Junkers airframe engineers from that engine project left during the merger, including Herbert Wagner and Adolf Muller who ended up relocating to Heinkel in 1940 and eventually re-starting work on what became the HeS 30. (keeping 2 separate Junkers/Jumo teams likely would have been the fastest development route and possibly led to the 004 being cancelled outright if the superior Wagner led design proceeded a year or so ahead of what the HeS 30 did historically)




    I believe the Me 163 addressed spin characteristics with its leading edge wing slots (fixed slots rather than slats) making it virtually impossible to spin. Tailless designs were probably more worthwhile to pursue than flying wings ... the delta planform seems to be the ultimate compromise between a pure flying wing and tailless aircraft and (in hindsight) also avoided the spin stability issue with the tip-vortex effect allowing extremely high angles of attack without stalling.

    There probably should have been a greater effort on tailless jet powered aircraft and less so for rocket. (without the benefit of hindsight, developing mixed-powered fighters might have been the safest bet particularly given rocket boosted jets are much easier to convert into pure jet powered aircraft than pure rocket to pure jet)

    Perhaps if the Horten brothers had been more open minded to introducing vertical stabilizers and rudders, the convergent development of delta wing design might have materialized sooner than Lippische's efforts alone. (Northrop might have had better luck there too, though they DID go in that direction with the XP-56 and XP-79 albeit without proper rudders, they more or less dropped progress in that direction with the B-39/49 projects)
     
  18. GregP

    GregP Well-Known Member

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    #18 GregP, Jul 9, 2015
    Last edited: Jul 9, 2015
    I agree kool kitty.

    My favirote tailess fighter for may years was the F-106 which was VERY good in many ways but did have the delta characeristic of very high turning drag. It could turn ona dime and give you change, but it wasn't going to be traveling very fast when the turn was completed.

    I do not believe that can be mitigated in a delta (but I haven't looked at delta wing characteristics since the 1970s ... and things DO get discovered), but a tailess swept wing is another anmial, turning-drag wise anyway, and generally doesn't slow down quite so quickly. I suppose you can find examples of tailess swept wings going both ways, but finding the fight test information is the hard part, at least for me.

    The Navy F7U Cutlass' Achilles heel was the engines. As for its handling, I've never heard anything bad other than getting "behind the power curve" on final approach, and if you do that in a conventional plane you're still in trouble. The Cutlass seems like a decent plane that only needed some thrust to make it as a good fighter. I DO recall that the hydraulic system wasn't well thought of, but all that is is a hydraulic pump, reservoir, accumulator, lines, servo valves, etc. and likely COULD be fixed to be acceptable rather easily had the engines delivered their expected performance.
     
  19. kool kitty89

    kool kitty89 Well-Known Member

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    Yeah, the tip vortex phenomenon that allows the extreme high AoA on deltas does so at the cost of very high drag, so a very serious consideration for energy-management dominated dogfights. (good for shorter take-off and landing though and avoiding need for added high-lift devices)

    Tailless swept wing platforms tend to have closer performance to their tailed counterparts with some trade in stability for reduced weight and/or drag (or just for keeping the fuselage short -useful for rockets and early jet aircraft to minimize ducting and exhaust length but the pod + single or twin boom arrangement is probably a more stable option there) but in any case you've got fully tailed deltas like the MiG-21 that have similar lift/drag trade-offs at high AoA and then you've got tailed and tailless highly swept almost-delta configurations like the F-15, F-4 Phantom, and (my personal favorite tailless aircraft) F4D Skyray.

    I'm not sure where the F-22's wing would fit in, but I'd expect it to behave much like a delta as well (though the leading edge sweep is less than the F-102 or F-106) and of course the likes of the F-15 and F-22 have massive amounts of thrust to power through high-drag maneuvers, plus the F-22's thrust vectoring.

    And I'm compelled to mention the F-16XL for its sleek lines alone. (I think that'd count more in the delta wing category, both in planform and tailless configurations)
     
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