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I'm very intrigued with how AeroVironment Switchblades: SW-300, and SW-600, steer their flight. There are plenty of images and animations and to my observation, none of the Switchblades have ailerons, elevators, or rudders. They have a vertical stabilizer and the rear wing can be considered as the horizontal stabilizer but, it seems, no control surfaces. So how do they steer their flight? do the switchblades use the oblique wing concept to control their flight path?

SW-300
Oblique Wing Concept

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    $\begingroup$ It looks like there’s some sort of aileron/flaperon on the front wings. $\endgroup$
    – Jim
    Jun 1 at 13:59
  • $\begingroup$ From the video, the larger of the two clearly has a rudder as well… $\endgroup$ Jun 1 at 14:17

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The ailerons of the Switchblade 300 are moveable. This can be clearly seen for example in this video, where they can be seen in their full up position. You can also make out that the wings are folded out with a spring without a locking mechanism. Therefore roll control is definitely realized via these ailerons.

Pitch control is performed (IMO) in one of the following ways:

  • Either the elevators are in reality elevons and therefore control roll and pitch
  • Or the elevator is tilted as a whole. Therefore, the mechanism carrying the swiveling mechanism, springs and elevator wing is swiveled by an independent servomotor.

Although I cannot find a source or good photo/video to prove either one of these theories, I suspect that these are elevons. This would have the advantage of having only 2 actuators, meaning less failure points, less complexity at the cost of having less control over the aircraft which is probably acceptable.

As far as I can see, yaw control is passive.

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    $\begingroup$ As a control theorist, I strongly disagree. It might not make a difference for a human pilot, but it definitely reduces controlability of the system $\endgroup$
    – U_flow
    Jun 1 at 19:47
  • $\begingroup$ Ok, makes sense now that I think about it. One thing's for sure, with such an arrangement you can't use differential aileron (elevon) throw to counteract adverse yaw. I used to run into this all the time when I did a lot of slope-soaring with radio-control models. Guys would talk about how they were using differential elevon throw to reduce adverse yaw with their Zagi-style "flying wings". (2 elevons were the only control surfaces.) (ctd) $\endgroup$ Jun 1 at 20:02
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    $\begingroup$ (ctd) I kept telling them, "All you are doing is mixing in a pitch input. It's nothing more and nothing less than deciding you are going to pull a little extra aft stick every time you make a roll input." Usually they didn't believe me. $\endgroup$ Jun 1 at 20:02
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    $\begingroup$ Yes that is true, lacking adverse yaw capability is probably the most prominent effect. But controlability is a pretty loose term. The lack of an evelope also results in a smaller control envelope which might cost you some performance. But apparently the effect is small enought that AeroViroment accepts this performance loss for lesser complexity. This is a bit odd, as I would excpect that the performance aspect would be more important... $\endgroup$
    – U_flow
    Jun 1 at 20:53
  • $\begingroup$ Not wishing to get into extended discussion, might the deployment of one control surface not generate yaw? Speaking mainly as a paraglider pilot where this is the primary method of instigating a turn, and paradoxically, owing to the low flying speed, the reverse of normal aileron behaviour (since a pg turns towards the lowered control surface). $\endgroup$
    – Frog
    Jun 3 at 20:42

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