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Comment by pedrocr | Hacker News Reader

> RC flying wings are regularly flown by humans without any software in between the input and control surfaces.

Technically this is definitely not true. Any modern RC wing will use software to do elevon mixing and get elevator/aileron input into the actual mechanical surfaces. It's possible to do this mechanically but software is so much simpler it's a no brainer to just have a servo per surface and do everything else in software.

It may be true in the spirit of this discussion in the sense that most RC wings just do fixed software mappings between inputs and outputs instead of having an on-board computer taking into account attitude/airspeed/etc and adjusting the inputs based on this. That's what's actually needed for aerodynamically unstable aircraft and RC wings generally don't need that, although similar kinds of hardware do exist in the RC world and are used sometimes.

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I mean, you could just as easily do the mixing on the TX side rather than the RX side. In that case, there is not software between the RX-servos and the control surfaces. I think that counts as 'no software between the input and control surfaces'.

The relevant question is whether there is an IMU providing feedback without which the plane would not fly.

It's my impression that "everybody" puts a flight controller between the servos and the receiver these days, either a sophisticated one running something like ArduPilot [1] or at least a cheap, dedicated flight stabilizer like (random pick) [2].

[1] http://ardupilot.org/copter/docs/common-choosing-a-flight-co...

[2] https://hobbyking.com/en_us/quanum-gyro.html

Maybe there is region differances here. Here in Sweden most RC-Wings, actually all, I have seen have been self made and do not use any active controller.

What kind of observations do you have to support your statement?

Ps. Most of them I have seen, and built, has been to play a game where you put a string on your tail and try to cut each others with the propeller. They were airodynamic stable.

This depends a lot on the cost of the model. For a powered model costing hundreds, or thousands of dollars, this is a wise addition because it protects the motor in the event of something going wrong (usually the control link dying)

However in RC gliders (slope especially) it's not necessary - the plane is made of foam and will bounce off any obstacle with minor damage, and they don't fly at long range. It's quite uncommon in this type of flying.

I've flown flying wing gliders that didn't have a flight controller - they work just fine. They're very aerobatic, though, which is less than ideal for carrying passengers.

The main issue I can see with this flying configuration is that the Centre of Gravity is extremely sensitive. You have quite a lot of leeway with a conventional airframe, but with a flying wing the CoG has to be spot-on or it becomes uncontrollable.

>However in RC gliders (slope especially) it's not necessary - the plane is made of foam and will bounce off any obstacle with minor damage, and they don't fly at long range. It's quite uncommon in this type of flying.

If your reference is simple foam planes this is true. But in high-performance applications like F3F people will run on-board accelerometer based control units that stabilize flight.

The whole discussion is a bit silly though. The standard for toys is clearly not the same as for a passenger carrying commercial airliner, even if sometimes they are very expensive toys...

Oh sure. Those F3B/F3Fs sure fall under the expensive category! I would probably add one for anything not foam.

> "everybody" puts a flight controller between the servos and the receiver these days

This was the point I was trying to address. It's definitely commonplace, but not essential, and the plane is aerodynamically stable without one.

A static mixer does not qualify as a stability augmentation system. SAS uses feedbacks from the state of the vehicle to change the plant dynamics.

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