VTOL question
Join Date: Feb 2006
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Plenhum burning reheat, that's what it needed... 
The pegasus design was pretty neat, but problematic to get much better performance out of. the nozzle design of cold-hot regions means messing with the fan efficiency would give a bit of a balance problem. The bypass ratio is 1.2, but the TSFC was not bad for its day at around 0.76. My own R&D took a 2.67 BPR and gave 4.3 BPR after a field mod to the fan, with a lower EGT and the same fuel flows, N1, N2. That would have suited a mixed flow to the rear nozzles with lower temps, and longitudinal balance by cold stream diverters. Getting higher bypass is not going to add more drag, the intakes have to be substantial for the low speed mass flow, so the diameter of the fan could easily have gone up to the 61" level of say a CFM56-3. With mod, the CFM56-3 would put out 30550 lbf but the installed weight would be higher, around 500lbs heavier; gotta go to Jenny Craigs. The CF34-10E would fit the same form factor of the AV8B, with some shoe horning, and would put out 26,500lbf for the standard EGT/fuel flows with a modified fan efficiency, both would use half the fuel flow for a given thrust (TSFC) of the Pegasus. I happen to like the flexibility that the Harrier gives, and it wasn't under built, as your tail ding would attest to down south in '82. Reducing the TSFC by half for around 25% more installed thrust would be worth the exercise machines. Now, making it low RCS would take some doing... that fan is a great reflector.
Higher bypass would have got rid of the hot gas ingestion issue in part, make some landings less exciting.
Higher bypass would have got rid of the hot gas ingestion issue in part, make some landings less exciting.
