Flying Trikes in a Tail First Mode ? - RC Groups
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May 21, 2015, 04:31 PM
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RickC_RCAV8R's Avatar
Question

Flying Trikes in a Tail First Mode ?


Gentlemen :

This may seem like a Noob question but as I have very little flying experience with trikes , I thought to ask the experts .

Q) If a guy wanted to reconfigure a trike to fly in a 'tail first' mode most of the time , what would have to be reversed besides the yaw servo ?

Reversing the yaw servo is obvious but is it a simple thing to just swap the M1 and M2 motors as well ? The idea was to use use the trike frame as the internal guts of an airplane must as one recently posted on the blogs . I think that the video clip was called something like " A Walk With My Pet" . Awesome looking plane . Perhaps a plane along the lines of this fellow or a Battlestar Galactica Viper MK4.

Just a thought . Any ideas here ? RickC
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May 22, 2015, 11:45 PM
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RickC_RCAV8R's Avatar
Did I answer my own question ? M1 and M2 motor revesals on their connection to the FC and the rudder servo reversal ? Does this even make sense ?
May 23, 2015, 03:35 AM
SSM
SSM
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Isn't it the elevator (pitch) and aileron (roll) that you need to reverse, rather than the rudder (yaw)?

Simon
May 23, 2015, 03:44 AM
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The problem with reversing rc channels is that it messes your stick commands / settings all up. I would think it's doable in the code, without ha ring to just make it work by randomly reversing channels.


As to your question about just swapping motors one and two, that Idea is right but then you're still left with the front / rear issue, again I would think it better to do it in code.


Here's a question, win the typical layout (T or Y style, single motor in rear) does it actually matter which motor you yaw? Just recently I saw a thread with a guy that yawed the front two motors, could you only yaw one of the front arms?
May 23, 2015, 10:56 AM
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RickC_RCAV8R's Avatar
Well , you fellas have me thinking about this ; a LOT now . As I have little experience with trikes but a couple of years on quads , I am trying to visualize what is actually happening to the model in flight with respect to the stix inputs . For a normal trike flying backwards , the elevator that controls fwd / back flight in to have the stick pulled back . This would have to be reversed for the mode I am proposing . The roll of the normal trike would use the aileron stick as usual . RPM varying is probably what is inducing the roll . A simple swapping of these motor inputs on the FC would take care of that . YAW . Yes , reversing the polarity of the yaw servo would be the simplest solution here as the motor would be out in front . I guess that I would have to build one to try it out AFTER I get to fly in the normal configuration mode firstly . No worries here .

As for the T or Y style frames and yaw ; I would think that tilting ANY or ALL of the motors would greatly increase the yaw rates ! The deal with tilting the motors currently popular is the gyroscopic torque generated by the spinning mass can wreck havoc on servos and linkages . (Applied Physics background) ALSO , the thrust vector of the tilted motor is changed at the sin of the angle of the motor . A system that I am proposing to try is to have ALL of the motors on FIXED mounts and have rudders installed under each one on the bottom of the spars . The linkage for this system would be simply made using beveled nylon gears , one for each frame leg rudder , being driven from a larger servo driven gear at the center of the frame body . The servo would drive the larger gear which is in turn , meshed with each of the 3 smaller rudder leg gears . A guy could run the gear bearings (plastic fabbed up ones) within the square carbon fiber tubing (10mm) spars to link to the rudders . I'm gonna try this one !

Thanx for the comments boys . Lots of food for thought here . Regards RickC
May 23, 2015, 11:05 AM
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Cereal Killer : Love the name ! It reminds me of a picture that I took for a Hallowe'en invitation whereby I costumed up in a Freddy Kruger kinda get-up whilst holding a box of cereal hostage and having the bloodied kitchen knife protruding its front . Backstabbed hostage like something from the movie PSYCHO . Good one .
May 28, 2015, 07:32 PM
benskoning's Avatar
I fail to see the difficulty. Just use a kk2 in manual (no auto level) and reverse your radio.
May 28, 2015, 10:04 PM
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KK motor mixer custom is as amazing as it is simple. You can do a motor layout on an inside out soda bottle and it will fly. No idea what its like in bf or cf but w/o a computer it gets no better. Heck it shows a picture after so you know if you got it right!
May 28, 2015, 10:49 PM
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RickC_RCAV8R's Avatar
I will give those ideas a shot IF my motors and ESCs ever arrive . The rest of the trike is complete waiting for these last parts .

I was just having problems wrapping my head around the whole idea of this backwards flight mode . I'm hoping to use this configuration for a jet like looking airframe . Foamie , most likely . Thanx for the comments ! RickC
May 30, 2015, 05:44 PM
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Baddmove's Avatar
I think I will build one and find out, pretty bored here lately with it being so windy ..
Last edited by Baddmove; May 30, 2015 at 11:42 PM.
May 31, 2015, 11:22 PM
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Baddmove's Avatar
So I have built one but I am still working on my landing gear..here's what I have so far..

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Jun 01, 2015, 03:11 AM
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RickC_RCAV8R's Avatar
Bad : That was a quick build if I may say so . Looks pretty good so far . If my eyes do not deceive me : Emax CF2822s for power , KK2.1.5 FC , Lemon RX on a HK Rotorbits modded frame . Kinda like the gear that I have on hand for my build . Please let me know of how you are planning to set up the FC for the backward orientation ; motor channel swapping and suchlike . Please also shoot some video when you can . I am hoping that my motors and ESCs arrive in the mail soon so I can try this for myself . Regards : Rick
Jun 01, 2015, 02:02 PM
benskoning's Avatar
Hmm, I dont see the requirement for a new copter, just reverse you radio channels (on the radio) It would be just like flying a trike backwards.
Jun 02, 2015, 02:02 AM
Registered User
So what you're wanting is a Tricopter with a reversed (from conventional Tris) elevator? Having the single rotor in the front instead of the back? It's definitely possible, but I would think some custom mixing would be required. I honestly couldn't really explain why, but simply reversing the elevator and aileron channel on the radio to a weight of -100 just doesn't sound like it would work. Again, just a gut feeling, absolutely no logic behind that assumption. One problem I could see with it is cameras. They would have to be bottom mounted, which is fine for HD cameras as long as your landing gear is long enough, but that's not really optimal for FPV. If I had to guess, camera positioning is likely why this design isn't more common. But camera arent a requirement, just a fun add-on, so it could definitely work.

Also, I'm positive that swapping motor outputs wouldn't work. It would instaflip on takeoff.
Jun 02, 2015, 12:36 PM
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RickC_RCAV8R's Avatar
@afitts :

The trike would be set up normally as far as the way it sits on the ground . Not inverted . I just want to re-assign the tail and nose orientation is all . A 180 on the geometry . As mentioned before , this model's configuration would be to use it as the internals for a foam jet type body .

Sounds simple , BUT ............ I thought to just swap the left and right motor connections to the FC and reverse the yaw for the old tail servo . I had hoped that this would keep the FC with its sensors happy as far as flying goes . Maybe it is just that easy just to place the FC oriented towards the tail and plug it in as normal . (Keep the reversed yaw though)

Perhaps I may be over thinking this solution somewhat . I just wish that my motors would arrive in the mail so I could try this out for myself and get some sleep . It bugs me as sometimes the problem seems pretty straight -forward and then again , something creeps in to complicate it . Thanx for the input .

@Baddmove : I am curious of what you find with the new trike in this orientation . Please advise as you progress .

@mokermeister : I was looking at the KK2.1.5 FC and the trike configuration menus used . Sure they show the motor layout and connection in a nice little picture , BUT for the rearward tail layout . Simply mounting the FC pointed forward reverses all of the compass related functions . If a guy were to use the APM2.6 and Mission Planner , this would show up as a compass that has an error of 180 degrees and reversed artificial horizon . Reversing the FC mount cures the Mission Planner instrumentation , but does the trike fly as the motors are reversed from left to right . This is not as easy as it sounds , is it ? Thanx for your input .


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