4 ms·
Probably can't escape moving surface stabilizer trim.
by jojobas 3y ago
Probably can't escape moving surface stabilizer trim.
- anilakar 3y agoHow so? Is there a sharp gradient in the boundary layer effect that makes it an on/off control system?
- jojobas 3y agoBoeing 747 stabilizer trim is achieved by rotating the entire tailplane by up to 15 degrees. The elevator is much smaller (less than 1/3 the area) and is deflected by a smaller angle. That's some serious force you'd have to apply with those air jets either throughout the cruise phase or takeoff/landing.
- anilakar 3y agoPositioning of nozzles in the video suggests they're experimenting with a BLC system, not just nozzles placed in the extremities like in the Harrier jets.
- tlb 3y agoPassenger jets need it because the center of gravity can vary a lot depending on passenger and cargo loading. A spy plane could probably be built with almost zero variation, with some careful fuel tank management.
- JumpCrisscross 3y agoThere are entire classes of tail-less aircraft. This is an abundantly solved problem.
- jojobas 3y agoHuge control surfaces harsh CoG limitations are the tradeoff.
- mpreda 3y agoMaybe the horizontal stabilizer trim can be replaced by a mobile weight inside the plane (moving along the front-to-back axis), that allows "trimming" the position of the center of mass.
- mpreda 3y agoCould even be "fuel trimming" between front and back wings; with the drawback that the action would be limited during both full and empty fuel states.
- Cthulhu_ 3y agoI'd assume there would be some constant air coming out of some of the nozzles for stability anyway.
- namibj 3y agoFunnily that's applicable to balancing unswept flying wings, as all high lift/low drag airfoils are unstable in pitch (though many are stable for inverse flight, i.e. if you get scared you'd have to turn upside down and are suddenly stable). I'm general, moving cog is potentially lossless, putting control surfaces into the airstream will always add drag.