4 ms·

I assume they mean aileronless rather than just flapless? Or is "flap" a general term for flaps, ailerons and rudder surfaces?

by hugh3 16y ago

artmageddon 16y ago
The three primary control surfaces on an aircraft are the ailerons(roll), rudder(yaw), and elevator(pitch). Flaps shouldn't be interchanged with any of these surfaces, especially the ailerons, since they perform different functions. Unfortunately the video is blocked for me so I can't see how it's flying, but from looking at this picture: http://img.metro.co.uk/i/pix/2010/09/28/article-1285661238268-0B5E6196000005DC-560297_636x300.jpg http://img.metro.co.uk/i/pix/2010/09/28/article-128566123826... it seems that the wings are one solid mass(save for the silver tab on the mid-rear edges). I'm almost inclined to chalk it up to bad journalism, but I'll have to reserve that judgment till I watch it. Edit: Looks like I'm partially right.. the jets replace all of the control surfaces. I have to admit that's some pretty cool technology. I feel the headlines don't do much justice, but it's probably a lot easier for the general public to understand something like "flapless" rather than trying to describe "a lack of moving parts."
notauser 16y ago
The airframe is based on their existing UAV family, which means it is pretty small and so the plane may not have a full set of conventional control surfaces to start with. It could also be a case of reporter-translation - anyway the film implied they had replaced all the moving control surfaces, including the ones in the tail. So it would have included ailerons etc if it had them. (I used to work in this facility on a different project, and it was one of the most interesting jobs I ever had. Just a shame it's so far from civilization.)
jrockway 16y ago
Flap means something to pilots, but not to popular audiences, I guess. What I gather from the article is that jets of air replicate the forces that the ailerons, rudder, and elevators normally provide. From watching the video, it also seems like it's missing flaps, because of the shape of the wing. Landing is something they can worry about later ;)
- yock 16y ago
  It could just be that the aircraft doesn't need flaps. The purpose of a flap is to change the wing geometry such that the aircraft can fly at a lower angle of attack. This allows the plane to fly slower without stalling the wing. If the aircraft can already fly sufficiently slow to land then it doesn't need mechanical flaps to adjust the wing geometry. As for replacing the control surfaces with jets of air, I can't help but wonder how that affects airflow around the aircraft. I'd bet something like this doesn't scale well to larger aircraft.
  - jrockway 16y ago
    I'd bet something like this doesn't scale well to larger aircraft. I think you're right. I've seen people's model DC-10s that they build, and apparently at that small scale, they don't even bother with coordinating the turns. If you want to turn, you just jam the rudder all the way left or right, and then the plane goes there. In a real DC-10... that probably doesn't work so well. (Tried this in X-Plane, and it doesn't really do anything. But the "edge cases" are poorly handled there; I can't even get a Cessna 172 to spin.)
    - yock 16y ago
      I don't know that full rudder deflection is really a corner case! In fact, the roll orientation of a plane shouldn't affect the effacacy of the rudder so long as the plane isn't in a slip or spin. The whole purpose of a rudder is to correct for a difference in lift between the wings in a bank. If there is no bank, and therefore no difference, the rudder should cause one.
      - jrockway 16y ago
        The airflow over the wings when stalling is the "corner case". The usual models don't apply; if they used a model that could handle any arbitrary airflow, then the sim would run at 1 frame per hour. So they make some assumptions for normal flight that are easier to calculate, then they make some other special assumptions for stalling, and switch between the models as necessary. I think. But apparently they don't do anything special for spins or uncoordinated turns, so you can't try this in X-Plane and be confident that a real plane would perform well. Anyone have a DC-10 they don't want?

I assume they mean aileronless rather than just flapless? Or is "flap" a general term for flaps, ailerons and rudder surfaces?

by hugh3 16y ago

I assume they mean aileronless rather than just flapless? Or is "flap" a general term for flaps, ailerons and rudder surfaces?

artmageddon 16y ago

The three primary control surfaces on an aircraft are the ailerons(roll), rudder(yaw), and elevator(pitch). Flaps shouldn't be interchanged with any of these surfaces, especially the ailerons, since they perform different functions. Unfortunately the video is blocked for me so I can't see how it's flying, but from looking at this picture: http://img.metro.co.uk/i/pix/2010/09/28/article-1285661238268-0B5E6196000005DC-560297_636x300.jpg http://img.metro.co.uk/i/pix/2010/09/28/article-128566123826... it seems that the wings are one solid mass(save for the silver tab on the mid-rear edges). I'm almost inclined to chalk it up to bad journalism, but I'll have to reserve that judgment till I watch it. Edit: Looks like I'm partially right.. the jets replace all of the control surfaces. I have to admit that's some pretty cool technology. I feel the headlines don't do much justice, but it's probably a lot easier for the general public to understand something like "flapless" rather than trying to describe "a lack of moving parts."

notauser 16y ago

The airframe is based on their existing UAV family, which means it is pretty small and so the plane may not have a full set of conventional control surfaces to start with. It could also be a case of reporter-translation - anyway the film implied they had replaced all the moving control surfaces, including the ones in the tail. So it would have included ailerons etc if it had them. (I used to work in this facility on a different project, and it was one of the most interesting jobs I ever had. Just a shame it's so far from civilization.)

jrockway 16y ago

Flap means something to pilots, but not to popular audiences, I guess. What I gather from the article is that jets of air replicate the forces that the ailerons, rudder, and elevators normally provide. From watching the video, it also seems like it's missing flaps, because of the shape of the wing. Landing is something they can worry about later ;)

yock 16y ago
It could just be that the aircraft doesn't need flaps. The purpose of a flap is to change the wing geometry such that the aircraft can fly at a lower angle of attack. This allows the plane to fly slower without stalling the wing. If the aircraft can already fly sufficiently slow to land then it doesn't need mechanical flaps to adjust the wing geometry. As for replacing the control surfaces with jets of air, I can't help but wonder how that affects airflow around the aircraft. I'd bet something like this doesn't scale well to larger aircraft.
- jrockway 16y ago
  I'd bet something like this doesn't scale well to larger aircraft. I think you're right. I've seen people's model DC-10s that they build, and apparently at that small scale, they don't even bother with coordinating the turns. If you want to turn, you just jam the rudder all the way left or right, and then the plane goes there. In a real DC-10... that probably doesn't work so well. (Tried this in X-Plane, and it doesn't really do anything. But the "edge cases" are poorly handled there; I can't even get a Cessna 172 to spin.)
  - yock 16y ago
    I don't know that full rudder deflection is really a corner case! In fact, the roll orientation of a plane shouldn't affect the effacacy of the rudder so long as the plane isn't in a slip or spin. The whole purpose of a rudder is to correct for a difference in lift between the wings in a bank. If there is no bank, and therefore no difference, the rudder should cause one.
    - jrockway 16y ago
      The airflow over the wings when stalling is the "corner case". The usual models don't apply; if they used a model that could handle any arbitrary airflow, then the sim would run at 1 frame per hour. So they make some assumptions for normal flight that are easier to calculate, then they make some other special assumptions for stalling, and switch between the models as necessary. I think. But apparently they don't do anything special for spins or uncoordinated turns, so you can't try this in X-Plane and be confident that a real plane would perform well. Anyone have a DC-10 they don't want?