JSF & Stealth & VTOL

[A Civilian]

Hi

I was hoping that someone with technical knowledge could help me out on a question todo with the F35 US mairine version.

My understanding of stealth technology is that the surface skin of the aircraft has to be very smooth and be angled correctly to give the aircraft the VLO ability. Any sort of blemish or bump would have adverse effect on the absorbation??? of radar waves and therefore the stealthness of the aircraft.

If this is true what would the effect of dozens of VTOL nozzels have on the 'stealth' ability. Would this dramaticly effect its ability?

[John Farley]

A Civilian

I see you fly radio-controlled aircraft. Well you must have two heads to work out how to move the ailerons the other way when it is coming towards you. So such ability deserves a reply.

While you are right about the need to control shape and surface finish to reduce radar signature the mechanism has more to do with controlling the direction in which the incoming energy is reflected away from rather than back to the original transmitter. Materials to absorb the energy are used more where you cannot fully control the reflection directions and are rather more secondary methods of signature reduction.

By dozens of Harrier type nozzles I guess you may be thinking of that aircraft’s reaction control jets at the wingtips nose and tail (6 in all) in addition to the 4 main engine nozzles. I agree such kit is hardly stealthy (radar or IR for that matter) but the X-35 V/STOL control system is quite a different kettle of fish.

In the hover the front of the aircraft is held up by a fan that is totally enclosed by flush fitting doors when away from the circuit, while the back end nozzle that rotates down for VSTOL is again well shielded when in the conventional flight mode. No pitch and yaw reaction controls are needed as the efflux from the fan and rear nozzle is varied to provide those functions. Which leaves only roll control, There are two underwing nozzles for this but I think you can safely assume that the skunk works guys are not entirely bereft of ideas for ensuring these roll posts (as they are termed) keep a fairly low profile.

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