Replicant, they aren't really VSTOL aircraft. This implies vertical take off. They are really STOVL (Which is pretty much how the Harrier is used anyway). The difference being that the JSF aircraft aren't really optimized (In terms of sizing) for vertical take off.
The Lockheed design (X-35) uses a shaft driven fan (i.e.-a lift fan behind the cockpit which is 'shaft driven' from the main engine in the rear fuselage). The rear nozzle of the X-35 is similar in design to the rear nozzle from the YAK-141 (They actually 'consulted' with YAK on the design of that nozzle). So the the vertical thrust vectors on the X-35 are due to the rear nozzle pointing down and the lift fan behind the cockpit.
The Boeing Design (X-32) has two nozzles with limited vector capabiliy (I think it is like 5 degrees angled forward from the vertical and 15 degrees back..not sure, but you get the idea) and they are obviously near the c.g. to either side in the fuselage (More in the bottom, then the sides). The main flow from the rear nozzle is diverted to those nozzles to transition to vertical flight.
Personally, I think the Boeing design will be more robust (i.e.- you don't have to worry about a transmission failure). However, the Lockheed design will allow STOVL versions to have a 'powered equipment' bay. That could be used to power ECM equipment, and some have even suggested, a Laser Weapon.
Ripsnort! You forgot the:
X-44 MANTAThis is a test plane based on the YF-22 prototype. Picture the YF-22 prototype. Remove all of the flight surfaces and controls (Including mechanical vectored thrust) and picture just the fuselage. Now add a cropped delta wing (Picture the wing planform of the production F-22A without flight control surfaces and 'more of' a delta shape). That's the plane! How do they 'control' it? Through the use of 'fluidic' controls. Its a way of effecting the thrust vector without any external vectoring mechanisms. In fact, that's why the X-36s nozzle has apparently never been seen in a public photograph. It apparently used fluidic controls as part of the YAW control of the vehicle (In conjuction with split ailerons). My guess is they are using either 'bleed' doors, or some sort of 'offset ring' control device (Hard to explain) to control boundary layer in the exhaust nozzle and thereby 'steer' the thrust vector without any external moving 'devices'. This can greatly reduce and help control RADAR Cross Section.
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Sundog
VMF-111 Devildogs'Criticism is always easier than craftmanship.'
[This message has been edited by Sundog (edited 02-22-2001).]
