@MCR87 Does this mean go to the mixer screen, edit E and change the weighting to -100?
Yes sir that’s how mine is setup, can you describe your control motions in manual and then in fbwa just using the rc?
@MCR87 - OK so I’ve done the entire setup again from scratch, compared my settings to yours and the important ones are the same.
So following the tests on this page: http://ardupilot.org/plane/docs/guide-vtail-plane.html
The roll and pitch tests are correct. The yaw is incorrect, in that if I yaw to the right (stick bottom right), then the right vtail goes down and the left vtail goes up. That’s the wrong way round isn’t it? The doc page is poorly written here, it should be less ambiguous, but I assume by ‘Both vtail surfaces go right’ it means the same directions that the right roll gives?
If I flip the reversals in SERVO2 and SERVO4 then the rudder/yaw is correct, but the pitch up and down is reversed.
This is driving me insane.
if you pretend you are in the pilot seat the control surface should wave at you when facing the direction of the stick input.
roll right; right aileron comes up and waves at you; left goes down; opposite for roll left
pull stick back; elevators come up and wave at you; opposite for pitch down
yaw right; rudder waves right; opposite for left
obviously vtail is just a rudder and elevator mixed but same applies.
if you input only rudder both should move the same direction of the stick when looking at plane from rear down.
have you tried switching the servo input cables on the vtail? this problem can occur on flying wings with elevons as well. it has to do with the way the servos are installed mechanically as the output shafts can be going different directions on each side with same PWM input.
Yes I’ve tried reversing the wiring of servo2 and servo4 (left/right vtail), same problems just in reverse! I can get 2/3 tests work at any one time, unless I’m being really thick (entirely possible), there’s something wrong with the mixing.
It took me quite a bit of trying to get mine setup properly, and I do remember going through the same struggles you did and somehow I got it to work. I will send you my taranis file once home maybe that will help.
Based on your servo connections, I believe it is entirely possible to have 2 “right vtails” so long that the servos respond correctly to all inputs.
As a reference, do all of the setup in FBWA mode. Do NOT use your transmitter – that gets confusing.
Work on 1 channel/servo at a time. Set the function. Leave your transmitter neutral and physically pitch the aircraft up. You should see the vtail move downward to correct the pitch. Return to neutra. Now roll the aircraft in 1 direction. The ailerons should attempt to correct that roll, and your rudder should move in the OPPOSITE direction of the roll (ie. out of that roll).
If one of the responses are correct but not the other, switch the servo function. If both responses are incorrect, switch the servo reversal.
Then proceed to the 2nd servo.Only after that’s done use your transmitter to double-check that your rc inputs aren’t switched.
@Naterater Thanks for the response, lots of ideas here for me to try. A lot of what you say is very different/contradicts the vtail doc page so if you’re right that should be updated ASAP. In particular, are you saying that in FBWA and I roll the aircraft to the right, the right aileron should go down, but the right vtail should go up? They should be opposite?
Correct. FBWA will try to keep the plane straight and level. By using FBWA you eliminate the transmitter as a source of error. Far too many people accidentally have transmitters reversed.
You’re right about the V-tail as well. When everything is correct, your left Vtail will move left and down as well.
@Naterater @MRC87 @Coby Ok thanks a lot for all the information. After reading up about vtails and yaw, all your tips and the elevon doc page, I think I’ve finally got it all setup correctly, and hope to get flying tomorrow.
I’m also still really unsure about the best way of getting airborne and landing, and how to autotune. Will be a nailbiting experience!
Thanks for all the help.
I can tell you that is is a quite durable platform minus where the wings are held together but if you look up nano talon on thingiverse you will find plenty of spares. I pile drove mine into the ground the other day because it lost a wing mid flight was really hauling. Again tape the tail and wings on when flying save you a crash. not sure what mine weights but i just arm it throttle to mid-60% hold pitch back and let her rip pretty easy to take off and land. For autotune just add the mode to flight modes flick the switch and work the controls left to right and up and down for a good long while the longer the better. once done switch back to fbwa or whatever flight mode you fly in. I have added fiber tape to the outside of mine and can tell you that it made a huge difference, I also tore the flimsy battery tray out and added a 1.5mm carbon plate on the bottom. Mainly bought this as a fun little tester and to let other folks fly. It is a fun little plane.
as tightly coupled as they have that v tail make sure your CG is in the proper range. don’t have a nano talon so not sure what it is. the wing looks pretty rectangular so about 20% of root chord back from leading edge; a guess if you want a little static stability margin. if you get it too far back it will want to nose up too much and stall. not an arduplane guru so not sure how good it is at masking those issues. since the tail moment is pretty short you do not have a lot of control authority in pitch and yaw. i keep reading it’s a nice little plane once it’s set up. i don’t know how many planes i have hauled away in trash bags. probably too many. take your time and have fun. take off is optional; landing is mandatory.
EDIT: ok it has a bit of sweep out at the tips. but since it’s straight trailing edge 20% likely still works. someone around here must know a good CG.
@MRC87 what is the purpose of the fiber tape?
Where do you add tape to keep the tail/wings, and what kind of tape? I was going to add some velcro strips but worried that it would affect the airflow. I’m going to do first flight without as I need to transport it in the box, and both wings and the tails are quite hard to pull out by hand so I think it’s reasonably safe.
@Coby There are little CG markers underneath the wings for you to use, nice little touch. I’ve taken note of some advice ‘a nose heavy plane flies poorly and a tail heavy plane flies once’! Will try and get the CG as good as possible but just a little nose heavy.
Triumph and Disaster!
OK so the good news is that I finally got flying, first time. Took off in FBWA and it just flew great. Quite a strong wind so I flew in a long rectangle with it going very slow in one direction and taking off like a rocket in the other direction. It was very, very slow at turning and reacting to roll and pitch movements - is that normal in FBWA? It also seemed to wobble quite a lot when flying straight - might have been wind but it was quite a lot, so suspect some inherent issue.
Landed and took off a few times without issue. Everytime I land in long grass the wings come off so I taped the wings onto the fuselage before I tried an autotune. Autotune seemed to go OK although still very poor response to movements.
Then I got bored and tried stabilize mode. Big mistake, that greatly exceeded my flying ability and during a turn it nosedived into the ground, broke the spur of one wing and broke the fuselage in half. Not a big deal, I can get replacements from a local store for not too much money, but clearly I need to read up on better ways of learning to fly!
Anyway, I got flying for the first time with no major issues, which is great. Thanks for all the tips here. Now I need to learn how to fly, how to tune etc! @MRC87 I’ll take a closer look at your params now re: tuning. I did turn the mixing_gain up to 1.0 which was good - left at the default of 0.5 would have been almost unuseable I think.
Flight Sims are a huge win for the rc community. Multicopters with stabilization are the easiest thing in rc to fly so transition to fixed wing takes some practice.
Practice in flight sim until control reversal is muscle memory.
The fiber tape help keeps everything together in a crash and I can speak from experience as my nano talon took a nose dive from 80m straight into the ground. Broke the center spar but fuselage stayed intact I was very surprised. It adds minimal weight and is quite durable for the belly landing aircraft. Use to work on a helicopter crew and fiber tape is your best friend.
You need to follow the autotune process to get the controller tuned before any of the other modes will perform nicely.
I’ve recently tuned my mini pixhawk equipped NT so know exactly how sluggish it responds until you have it tuned. I also adjusted the mixing gain to give more elevator movement (0.6).
Sorry to jump in late in this discussion. My guidance is to never reverse a channel or set trim on the RC transmitter. Begin setting up your nano talon (or any other V-tail, A-tail, or Wing) with your RC transmitter set to factory default. Set Servo 2 and Servo 4 for Left and Right V-tial (this is standards but you could use any channels) and move the plane in pitch and role. Reverse Servo channels if needed to achieve proper motion. If you cannot achieve proper motion when you move the plane in pitch and role, then interchange the two tail servos (switch left and right) and try again. In one or the other connection the V-tail (or A-tail) will work correctly. Now test pitch and roll with your RC transmitter. Reverse RC channels (in Config/Tune) to achieve proper motion. This sequence works 100% of the time for all planes!
Thanks everyone for the tips and advice!
@Ronald_Pandolfi Yes you’re absolutely correct! This is the same thing that @Naterater advised, and it definitely works. In addition I was completely confused by the ambiguous instructions on the vtail doc page.
@hangarspace Thanks for the info, when I tape it back together the first thing I’ll do is an autotune. I actually set the mixing_gain to 1.0 before taking off. Oddly there was very little pitch control in FBWA, but too much in stabilize/manual.
@MRC87 Fiber tape ebayed! So what about the wings? When I had my big crash at the end it broke one of the wing spurs, possibly because I had taped the wings to the fuselage. I think I need to find a way to keep the wings on more during flight, but still come off during a crash. Or possibly a big crash will always break something…