I have an aquaintance with WAY too much time on his hands, and he's done a little number crunching for the F-35, and said it was OK to post this.
Quote:
I've often ridiculed myself for being an airplane design geek, but I think I've gone overboard with this hobby. I've accumulated unclassified data from many sources and attempted to calculate the performance of all F-35 models. It was just too tempting a target of opportunity. Much of the work is based on SWAGs but it's time to publish or perish. Anyway, I'll get the discussion rolling with a few observations. The "C" model is my choice for the thinking man's war machine. It's relatively slow (M=1.6) and sluggish (P sub s 11% lower than "A" at the 30k ft maneuver point indicating inferior acceleration/climb) but it can maneuver well and sure haul bombs a far piece. I may be seeing the light on the F-18E concept (wait, that can't be right). Oh yeah, it can land on ships too...way cool. There are some problems though. I'd like to have a bringback weight around 10000 lbs but the approach speed is too high resulting in an unacceptable (to a structures guy) sink speed. My personal cut off is 24 ft/sec. With a little work on the high lift system (maybe fowler flaps?) and some heroic weight savings, it has possibilities for improvement. On the other hand, maybe I'm too conservative with the estimated maximum lift coefficient (Clmax=1.7). A little homework on the "B" model shows why STOVL is not popular. Range and payload are inferior, no suprise, and it is marginal on vertical landing bringback, a measly 3000 lbs by my calcs. The relative cost of the "B" is probably between 2 and 3 times the "A" because of unique features and low production. The "A" model should be very popular. It is the smallest and cheapest version by far. Performance as a useful weapon system should be superior to anything today. Another observation, the JSF is not from the John Boyd school of aircraft design. Instead of emphasizing point performance, these things push range, payload and versatility. Let's coin a new phrase "fuel is life". Here are some comparisons:
Empty weight for A,B,C = 25000,30000,28200
Reference wing area = 460, 460, 620 sq ft
Top speeds (SL knots,M @altitude) = (790,2.06),(790,2.05),(710,1.6)
Turn rate @ 30k ft = 8.0, 7.4, 8.8 deg/sec
Sustained g's @ 30k ft = 4.0, 3.7, 4.4 g's
Specific excess power, Ps @30k ft, 1g = 360, 332, 320 ft/sec
Cruise L/D @ 40k ft. = 10.4, 10.4, 11.9
Cruise specific range = .15, .14, .15 n.m. per pound of fuel
Take-off weight for basic interdiction mission = 46300,46400,50300lbs
Initial rate of climb = 50800, 50700, 44400 ft/min
Interdiction mission payload = 2 x GBU-32 + 2 x AIM-9 internally
Internal fuel = 18300, 13400, 19100 lbs
Mission Radius for interdiction mission = 840, 420, 920 n.m.
There's lots more. I don't know if it's correct, but it has some scientific basis. Anyone have any nagging questions? Maybe I can give some insight.