kool kitty89
Senior Master Sergeant
Moved from the other discussion given how far off topic it went, perhaps worth moving the discussion on chemical/nuclear weapons here too? (at least as far as their ability to be deployed on cruise missles)
So, on top of that, use of easier to burn (yet still cheap to synthesize) fuels might have accelerated pulse jet and turbojet development and improved some of the reliability problems Heinkel was having early on, particularly those relating to unstable combustion and hot spots (enough to make the early test designs only work on hydrogen and still plaguing the HeS-8 for most if not all of its development period -in fact the problems with the HeS 8 seemed worse than those experienced when the previous HeS 3/6 program wound down). And while the HeS 3 and 6 were bulky, they were still relatively light and compact enough to be decent for high-speed configurations, and narrower than Whittle's designs. (perhaps better embedded in the body/tail of a missile than piggyback -the HeS 8 was much narrower but more troublesome, perhaps less so as a 'throw away' engine)
Aside from that, development of specifically designed, inexpensive, short-life engines may have bypassed the issues with usefully long service lives/TBO times and turbine wear issues, though developments focusing on even cheaper engines using less or no stainless steel in the hot section (something Heinkel's early designs used heavily) would have needed a bit of work. (with the superior wear characteristics of radial turbines, an uncooled steel bladed configuration may have been usable, and the disadvantage of sheer size/weight of costly stainless steel would be mitigated -in fact, you could increase the thickness of plain steel turbine in this case, compromising spool-up time, and adding to weight slightly, but being fairly unimportant for such a throw-away engine)
I should note that the HeS 3 of 1939 only produced slightly more than half the thrust of the 004B (about 990~1100 lbf) so the payload increases over the pulse jet powered V1 wouldn't be as great. (perhaps closer to a 50% gain plus improved range due to altitude and much better fuel consumption -even the crappy 1.6 lb/lbf/hr of Ohain's early engines was more than 2x as good as the Argus pulse jets)
Finally, mild steel is very easy to weld, so the quality/consistency advantages seen in the cromadur vs tinadur blades would have been relevant in spite of the low creep strength and oxidation issues. (this applies to a hypothetical mild steel turbine on the 004 as well) In fact, given there's zero nickel or other typically creep improving metals in cromadur, it may not hold up that much better under heat+stress than plain low carbon mild steel, with oxidation and related erosion being the main problem. (unimportant for an engine only intended to run for a couple hours at most -possibly unworkable if attempted on a combat aircraft though, aside from maybe a point interceptor that had engines/turbines replaced after each mission -I highly doubt even 10 hour service TBO would be reliable with such engines, Jumo worse than Heinkel given the cooling air might oxidize the turbine blades from within, plus the stresses are much higher than on the radial blades)
The tendency for V2s to bury themselves before detonating might have made them more effective as chemical weapons systems than conventional, or at least have a lesser detriment to effectiveness. Potential for the earth/debris to muffle the explosion and cause the dispersion of gas to be more focused at low level and remain concentrated around populated areas more, that and potentially contaminating groundwater.
One alternative to V1s might have been turbojet powered cruise missiles, something that may have been further benefited by the relatively low cost of materials and man-hours per engine for (and limited service life) of the Jumo 004B, or perhaps an even simpler specialized low-life engine that used even more mild steel in place of stainless alloys. (I do wonder how long a plain mild steel turbine might hold up when used in a similar air-cooled configuration, especially with zero concern for throttle changes further increasing wear)
More costly than a V1 to be sure, but perhaps a great deal less costly than the V2, and faster than the V1, heavier payload, and potentially longer range, plus fewer hurdles with vibration to work though. (with the pulse jet's fuel pressure regulation issues at altitude avoided, pushing heights more around 10,000 ft cruising around 500 MPH would make it both hard for AA to hit and impossible for fighters to intercept)
Even if using standard 004B engines, it should have been more practical, reliable, and less costly to manufacture/operate than the jet powered mistel developments on the drawing board, and probably could have been adapted/executed sooner had it actually been developed as part of the V1 program. (500 mph cruise missiles carrying more than a cookie's worth of high explosives at 500 MPH may have even been more cost effective in terms of damage operational use than the actual V1 -plus, just slow/low enough to still waste resources TRYING to intercept them ... head-on/side long passes at top speed might have had limited success, enough to be a major distraction as well as a strategic weapon)
I should probably bring it up in one of the Jet engine threads too (or start a cruise missile thread), but the un-cooled radial turbine that allowed relatively consistent operation on Heinkel/Ohain's early engines may have been well suited to short-life disposable engines made with most/all hot components of plain steel. (aside from the bearings, Ohain's HeS 3 and 6 were nearly entirely mild and stainless sheet steel and aluminum, including the compressor and diffuser -using rolled or forged aluminum blades fastened to a steel hub for the impeller, less aerodynamically efficient but faster/simpler to construct than the machined impellers used in most superchargers -also easier for Heinkel's airframe manufacturing facilities to construct in the late 1930s prior to any access to engine manufacturing facilities)
Such disposable engines may have been aided somewhat by specific fuels being used. Methanol in particular has a lower flame temperature and may have made for a somewhat lower turbine/exhaust temp and lesser wear and easier to start Heinkel's early, hydrogen-warmup dependent vaporization dependent combustion systems on -soot tending to clog the injectors if gasoline/kerosene was introduced too soon, or especially at start-up. (but also less than half the energy density of kerosene, reducing range or payload ... but also the cheapest synthetic fuel to manufacture AND its corrosive issues -especially with aluminum- being totally moot in a disposable machine -blending with ethanol, acetone, ether, among others could improve things somewhat, some vaporizing easier than others -ethanol the worst of those, diethyl ether better than methanol, dimethyl ether would be useful too but it's a gas unless under modest pressure or dissolved in other fuels)
In fact, methanol is one of the easiest fuels to get pulse jet engines to reliably function on, and may have even accelerated V1 development somewhat and eased starting compared to the acetylene+gasoline/kerosene start-up procedure. (diethyl ether would probably work even better, dimethyl more so and almost as cheap to produce as methanol but would need pressure containment somewhat similar to butane, or disolved/blended with other fuels -methanol included, though given the pressure feed system on the V1, omitting the fuel pump and using pressurized liquified fuel directly might have been useful and no special start-up fuel needed -could work in a turbojet just as well, and even simplify start-up)
So, on top of that, use of easier to burn (yet still cheap to synthesize) fuels might have accelerated pulse jet and turbojet development and improved some of the reliability problems Heinkel was having early on, particularly those relating to unstable combustion and hot spots (enough to make the early test designs only work on hydrogen and still plaguing the HeS-8 for most if not all of its development period -in fact the problems with the HeS 8 seemed worse than those experienced when the previous HeS 3/6 program wound down). And while the HeS 3 and 6 were bulky, they were still relatively light and compact enough to be decent for high-speed configurations, and narrower than Whittle's designs. (perhaps better embedded in the body/tail of a missile than piggyback -the HeS 8 was much narrower but more troublesome, perhaps less so as a 'throw away' engine)
Aside from that, development of specifically designed, inexpensive, short-life engines may have bypassed the issues with usefully long service lives/TBO times and turbine wear issues, though developments focusing on even cheaper engines using less or no stainless steel in the hot section (something Heinkel's early designs used heavily) would have needed a bit of work. (with the superior wear characteristics of radial turbines, an uncooled steel bladed configuration may have been usable, and the disadvantage of sheer size/weight of costly stainless steel would be mitigated -in fact, you could increase the thickness of plain steel turbine in this case, compromising spool-up time, and adding to weight slightly, but being fairly unimportant for such a throw-away engine)
I should note that the HeS 3 of 1939 only produced slightly more than half the thrust of the 004B (about 990~1100 lbf) so the payload increases over the pulse jet powered V1 wouldn't be as great. (perhaps closer to a 50% gain plus improved range due to altitude and much better fuel consumption -even the crappy 1.6 lb/lbf/hr of Ohain's early engines was more than 2x as good as the Argus pulse jets)
Finally, mild steel is very easy to weld, so the quality/consistency advantages seen in the cromadur vs tinadur blades would have been relevant in spite of the low creep strength and oxidation issues. (this applies to a hypothetical mild steel turbine on the 004 as well) In fact, given there's zero nickel or other typically creep improving metals in cromadur, it may not hold up that much better under heat+stress than plain low carbon mild steel, with oxidation and related erosion being the main problem. (unimportant for an engine only intended to run for a couple hours at most -possibly unworkable if attempted on a combat aircraft though, aside from maybe a point interceptor that had engines/turbines replaced after each mission -I highly doubt even 10 hour service TBO would be reliable with such engines, Jumo worse than Heinkel given the cooling air might oxidize the turbine blades from within, plus the stresses are much higher than on the radial blades)
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