rtfm
Well-Known Member
Hi,
I have been off HBA for most of this year, mainly because I have made scant progress with the Razorback due to funding issues. In the interim, however, I immersed myself in the RC world, and built a scale version of the Razorback. The idea was to keep the dream alive by building something I could actually afford. The little 1/3 scale Razorback is ready to pull molds from, and the wings are shaped.
During my "RC excursion" I have learned a great deal about the hobby, and have begun to think of the possibilities digital proportional controls might have in full-size planes.
Basically, I'm toying with the idea of fitting servos to all control surfaces, and controlling them from an RC transmitter. It may sound crazy, but I think the idea has legs.
The only real difficulty I see is coupling the physical stick to the RC controller. But that is just an engineering detail which can be worked out later.
The other perceived issue is the lack of tactile feedback. But as Orion and others have noted in other threads, this is far less of an issue than it would initially seem.
So there you have it...
A fully digital aircraft. My current receiver (about $35) allows for 16 independent channels. That covers 1x throttle, 2x ailerons, 2x flaps, 2x elevators. I could even split the ailerons and flaps into multiple segments, and control each individually (very easy to program into the controller). That means I could deflect alternate segments up/down to act as speed brakes (the RC guys call this "crow" for some reason). Up to .26G of braking can be achieved...
Cost?
Transmitter: $160
Servos: Let's say $300 per servo = from $2,100 upwards, depending on how fancy I want to get
[EDIT] If one splits the control surfaces up into smaller sections each controlled by a servo, one can use smaller servos (ie far cheaper). The cost per servo then goes down dramatically - to about $50 per servo - and that's top dollar for top of the line digital, metal geared servos).
Receivers: $35 ea = from $245 total (and up - depending on complexity)
A starting point of about $2500
And for that you can have auto checklists (make them as comprehensive as you like), auditory feedback on altitude, speed, AoA, and just about anything else you can imagine. And if you get lost, hit the RTB button and get flown home...
Thoughts?
Duncan
In case you've forgotten what the Razorback is going to look like...
I have been off HBA for most of this year, mainly because I have made scant progress with the Razorback due to funding issues. In the interim, however, I immersed myself in the RC world, and built a scale version of the Razorback. The idea was to keep the dream alive by building something I could actually afford. The little 1/3 scale Razorback is ready to pull molds from, and the wings are shaped.
During my "RC excursion" I have learned a great deal about the hobby, and have begun to think of the possibilities digital proportional controls might have in full-size planes.
Basically, I'm toying with the idea of fitting servos to all control surfaces, and controlling them from an RC transmitter. It may sound crazy, but I think the idea has legs.
- RC transmitters/receivers are extremely reliable, and have been subjected to multiple thousands of hours of real-world testing. Sure, the testing is being conducted by RC pilots flying scale planes, but modern RC kit simply doesn't fail. Almost every single in-flight failure can be traced back to "dumb thumbs" (ie pilot error), poor maintenance/construction or failure to observe simple safety rules (like checking fuel levels, battery power etc). With the current crop of high-end transmitters, failure is for all practical purposes a thing of the past.
- RC servos are similarly robust, both in terms of torque/speed and reliability. The larger servos rival the servos used in light aircraft auto pilot systems (and are similarly priced...) For example, the Seiko UAV servos are capable of over 90kg/cm or torque at a cost of only $228. And that's the lower end of the scale.
Seiko UAV Servo PS-050
This one produces over 230kg/cm (at 12v) - There are others - faster and with more torque up to about $600. But why bother?
- These (and better/more expensive) servos are FAST (the more you pay, the faster they get). Go figure...
- The transmitters are robust, and extremely versatile as far as programming is concerned. For example, the Taranis (which I own) costs less than $160, and can easily be programmed to provide:
- Differential aileron deflections
- Aileron/elevator/rudder/throttle coupling of whatever type you wish. Typically (as we know), a wing with dihedral in a turn requires (1)additional throttle, (2) some back pressure (3) some rudder. All this can be provided by a simple controller mix (and can be adjusted infinitely if you don't get it right first time). How cool to go into a beautifully co-ordinated turn simply by deflecting the ailerons?
- Audible feedback on altitude/speed/battery levels
- "Exponential" - i.e. movement of the stick close to the centre produce less control surface movement than the same stick deflections further from the centre. This has the effect of "damping" small control inputs, making the ride smoother
- Feedback from the telemetry of the receiver can auto trigger the degree of exponential - so, for example, at slow speeds, at slow speeds, the amount of actual flying surface deflection can be at it maximum, but as speed increases, so the maximum control surface deflection decreases
- Fitted with one of the gyro-enhanced stability modules, the plane can be flown "naked" - i.e. with no stability enhancement, in "2D mode" which is basically wing leveling mode or "3D mode" which fixes the orientation of the plane according to stick input - automatically compensating for wind gusts, turbulence etc. So you get into a spin. Let go the stick (good idea anyway) and hit the "2D" switch. The onboard gyros instantly apply rudder to stop the spin, and have you flying S&L in seconds. Want to do it yourself? Be my guest. Don't hit the "Panic" button...
- Fitted with a GPS module (about $100) if you get lost, you can hit the Return to Base button, and your plane will fly you unerringly back to where you took off and circle the field once it gets there.
The only real difficulty I see is coupling the physical stick to the RC controller. But that is just an engineering detail which can be worked out later.
The other perceived issue is the lack of tactile feedback. But as Orion and others have noted in other threads, this is far less of an issue than it would initially seem.
So there you have it...
A fully digital aircraft. My current receiver (about $35) allows for 16 independent channels. That covers 1x throttle, 2x ailerons, 2x flaps, 2x elevators. I could even split the ailerons and flaps into multiple segments, and control each individually (very easy to program into the controller). That means I could deflect alternate segments up/down to act as speed brakes (the RC guys call this "crow" for some reason). Up to .26G of braking can be achieved...
Cost?
Transmitter: $160
Servos: Let's say $300 per servo = from $2,100 upwards, depending on how fancy I want to get
[EDIT] If one splits the control surfaces up into smaller sections each controlled by a servo, one can use smaller servos (ie far cheaper). The cost per servo then goes down dramatically - to about $50 per servo - and that's top dollar for top of the line digital, metal geared servos).
Receivers: $35 ea = from $245 total (and up - depending on complexity)
A starting point of about $2500
And for that you can have auto checklists (make them as comprehensive as you like), auditory feedback on altitude, speed, AoA, and just about anything else you can imagine. And if you get lost, hit the RTB button and get flown home...
Thoughts?
Duncan
In case you've forgotten what the Razorback is going to look like...
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