Hi Guys, first post here after I've maidened my new purchase of an X8 with FY21AP and Hornet OSD this evening. I'm flying on UHF and camera is on 2.4Ghz. I set off initially just to fly by line of sight to get the feel of the wing (have flown lots of planks and helis) and how it responded - the FY21AP was set to RC (manual) mode deliberately as I wanted to try out the Auto Balance Mode in flight to again get the feel of how it behaved. I set it up correctly (patiently let the GPS find 10 satellites) so all was fine. I did 3-4 circuits - all was fine and thought it was time to engage the ABM.
oh dear.....very nearly lost the whole lot. I was flying at approx 100m height (my friend was watching via the goggles) and flicked the switch to move to ABM and it literally went into a steep spiral dive. So clearly what the FY21AP thought was "balanced" was severely off. I only just managed to go back to manual and recover with about 3-5 metres to spare!
Has this happened to anyone else before? - and any tips on how to re-calibrate the FY21AP and what I might have done to cause it be so massively out from a calibration perspective?
Thanks, Ed
You've probably got your control surfaces reversed .
Did you test it on the ground ? They should do the opposite to what you would do. I.e bank right and the right elevon should go down and the opposite up to counteract the roll etc etc
If this is the FY21AP and not the FY31AP (which is usual with the Hornet) then you MUST remember that when you switch it on, it MUST be absolutely level. I made this mistake previously by putting the plane on it's side while I fiddled to get it connected and BAM! when you switch it on, it then spends the first 3 seconds setting it's equilibrium in that moment to it's natural straight and level position and when you flick it on in flight it finds that neutral 'position' easily ending in a dive, spiral dive or in my case at over 45 degrees, a snap roll!
I sorted this out by installing a switch on the outside of the plane so that I could rest it on flat ground, hold the wings level and switch on. Doing it that way gives you a great ABM and perfect RTL everytime. Get it wrong and it WILL KILL YOU! :)
Or as Davey says... have you checked the direction of throws when engaged? They should counter the pitch and yaw movement.
Richard
Also make sure you use a good quality, high amperage UBEC to power it not the BEC of your ESC. The early FY20 and 21s were sensitive to input voltage drops.
Mick
Thanks guys - sorry not to respond earlier to your very quick response Mick & Richard (and also thanks to whoever corrected my initial post by putting it in the right section for Auto Pilot questions!)
hmm... it is the FY21AP, I did boot it all up with the wings level sitting happily on the grass - it may not have been 100% level due to the Fuse shape but short of a cradle with spirit levels it couldn't have been better.
Regarding the control surfaces being reversed - I was flying in manual mode very happily before engaging ABM as I wanted to trim/get the feel of how the X8 behaves based on normal LOS before putting on the goggles - so that was all fine.
I'm planning to go out tonight and will check/test again - it may be that I have connected the servo's up the wrong way and whilst for some reason they work correctly on RC (manual) mode, the minute they go into ABM, if the singals are reversed, I could see why a steep spiral dive would be the result.
Interesting to share that I found flying manually even in calm air requires quite a lot of inputs - I dont think I could live without ABM when flying FPV - I cant wait to get there!!!
thanks again and will share the findings/solution to complete the post.
cheers, Ed
Quote from: Flying Ed on June 28, 2013, 11:22:56 AM
Regarding the control surfaces being reversed - I was flying in manual mode very happily before engaging ABM as I wanted to trim/get the feel of how the X8 behaves based on normal LOS before putting on the goggles - so that was all fine.
You can have the Fy21 installed but with the 3 adjusting pots turned the wrong way from their centre position and the effect will be disasterous..... but in manual mode (RC) the FY21 is switched out so yes, you would be able to fly the plane just fine.
The 3 adjusment pots when at the centre position (12 o clock) have no effect on the stabilisation
turn them either way from centre and they start to crank up the amount of movemenet the stabilisation system gives
BUT
turning them clockwise gets the surfaces moving one way to stabilise
turning them anticlockwise turns them the other way !
You need to be 110% certain that you have the aileron/elevator/rudder movement all going the correct direction to CORRECT any unwanted movement of the plane, it does sound like one or more of yours are going the wrong way :(
I have 2 planes with FY21AP in them and I have mine with the adjuster turned almost all the way (in the direction they need to be) and they've been working fine including RTL and ABM for nearly 2 years now.
Once you have it set up correct you'll really enjoy flying with it :)
PK
Hi Again - thanks PK for your suggest - you're 100% spot on - karma awarded!
I played with the 3 pots on the FY21AP and found the mid-point and then with ABM on checked there was no auto-correction.
Then found that the correct direction of adjustment gave me exactly what I needed - so it looks great.
no wonder it went haywire when I switched on ABM!! I guess the lesson is to check what ABM does when engaged on the ground before being 100ft up in the air!
Really excited about this and looking forward to trying out RTL on top of ABM. Only problem is its a bit windy right now and my launchman has gone off to play golf for the weekend. what a loser! ;-) I'm somewhat reluctant to try and launch on my own given the size of the X8.
Thanks guys for your efforts in helping - I know I'm going to be back with more questions but I'm getting there!
cheers, Ed
Quote from: Flying Ed on June 28, 2013, 08:58:36 PM
Hi Again - thanks PK for your suggest - you're 100% spot on - karma awarded!
I played with the 3 pots on the FY21AP and found the mid-point and then with ABM on checked there was no auto-correction.
I don't think that's quite right :) I assume you are saying the surfaces are NOT moving now in ABM mode? If your gain is set to zero (12 o'clock) your RTH and ABM mode will do sweet FA when you engage.
As I said in my post you need to make sure the control surfaces are moving in the opposite direction to stick input when you move the plane on the ground in ABM mode.
You need to move the pots to the correct side (from zero).
Hi Davey - thanks for the post, I did move the pots in the "right" side of the centre position so didn't leave them stuck at 12 o'clock. ABM felt very sluggish when engaged and initiating a turn and also I got some nasty oscillation which I corrected by turning gain down. RTL send the whole thing into a dive so something is definitely nit quite right. I'm going to do a full reset of the AP - it was bought second hand and I think that would be the best way to remove the gremlins - thanks again!
I still think you've got the control surfaces moving in the wrong directions.
Can you enable ABM on the ground, pick up the plane and then pitch and roll it in your hands.. Please tell us what way each surface moves when you :
(From the 'pilots' point of view)
A) roll right
B) roll left
C) pitch up the nose
D) pitch down the nose
Hi Davey - I've got the elevens moving correctly in abm mode. Ie if (from a fpv perspective) nose is pitched down the elevons both move up to correct and vice versa - equally if x8 is rolled left then right elevon goes up and left elevon goes down. The current challenge is major pitch oscillation when abm enabled in flight even with very light gain set on the fy21ap - plus rtl sends the x8 into a mad spin/dive.
I inherited the fy21ap wiring setup from the previous owner who never really got it flying - I'm almost certain the the wiring from the AP to the servos / UHF rx are not right - I briefly read last night that a jumper is also needed on the AP to manage elevons and I'm almost 100% certain it's been put on the wrong pins. I think a reset and a thorough review of the wiring configuration is the next step before any more flying!! She properly grounded for now!!!!
Would love any help than can be shared on wiring once i've done my research and re-wired the ap - i'll post it here. Thanks again for your help - its really appreciated - I know the fy21ap is a good piece of kit but it just needs to be wired up correctly for elevons.
Thanks again, Ed
Have you calibrated the IMU's? and do you still get the same issue with the gains at say 1 or 11 o'clock (depending on surface direction)..
Quote from: Flying Ed on July 03, 2013, 12:08:55 PM
I'm almost certain the the wiring from the AP to the servos / UHF rx are not right - I briefly read last night that a jumper is also needed on the AP to manage elevons and I'm almost 100% certain it's been put on the wrong pins.
Hi Ed,
Page 18 of the PDF manual
http://www.fpvflying.com/downloads/FY-21AP-manual.pdf (http://www.fpvflying.com/downloads/FY-21AP-manual.pdf)
mentions about the jumper and its position if using elevons.
PK
Yeah Ed.. As above you have to make sure the FY21AP is doing the mixing not your TX :)
Thanks Davey - I've pulled the FY21AP out to re-calibrate it and found that one of the rubber bands on the suspension cradle had actually given up so although that wont be the real issue, was causing the AP to be sitting 2mm lower in one corner.
I'm off to buy some replacements that are as similar as possible to the originals and will search round maplins/B&Q/homebase but before embarking on a wild goose chase are there any recommendations out there as to which rubber bands work best as replacements - i've seen loads of comments saying how bad the stock solution is and that they perish in direct sunlight but wondered what others had done in the event of needing to replace one or all of them?
thanks!
as long as you get four bands of the same size you should be fine :)
You could try Halfords for some sump plug O-rings.
I've got a massive box of silicone O-rings I bought on ebay years ago, a few of those have ended up as prop savers etc. on RC stuff :laugh:
Quote from: Flying Ed on July 08, 2013, 01:02:28 PM
Thanks Davey - I've pulled the FY21AP out to re-calibrate it and found that one of the rubber bands on the suspension cradle had actually given up so although that wont be the real issue, was causing the AP to be sitting 2mm lower in one corner.
I'm off to buy some replacements that are as similar as possible to the originals and will search round maplins/B&Q/homebase but before embarking on a wild goose chase are there any recommendations out there as to which rubber bands work best as replacements - i've seen loads of comments saying how bad the stock solution is and that they perish in direct sunlight but wondered what others had done in the event of needing to replace one or all of them?
thanks!
Ed, Feiyetech no longer recommend using that suspended base and I must say since I gave up on it, I've never had vibration issues (or worse, a cockeyed IMU) on either the FY21AP or FY31AP.
Coyote, myself and a few others use a sticky pad (available from everywhere, as well as Poundland) that you cut into 4 small pieces and attach underside on all 4 corners. I have two layers and it really works well! Also helps to have a base of nylon weave tape between the fuse foam and the sticky pads, then they will stay!
Also, when you fly, look at that number on the top left side (AERO) - it's a representation of your vibrations on board. With the 21 if it gets high - anywhere between 000 and 1000, you could be in for fun... if it gets high switch to RC as with ABM, ACM, RTL etc if it's vibey, it could literally snap roll the plane.
R
cheers Matey - that's a great help - stikcy pads / nylon weave tape where we come.
Re the error rate message on the OSD - my 2 flying sessions to date were only ever LOS flying w/o the fatshark goggles and funnily enough I only just got a corrective contact lense for my left eye on Saturday as I'm -4.5 in my left eye and 20/20 in my right eye - so to date I've never really been able to read the left hand side of my screen well due to being so blind on the left eye. (I know the data is presented on both screens but trust me when your brain is as confused as mine due to such a discrepency its very hard to read the data on the "left hand side" of the screen.
Just eradicating those problems one at a time on my journey towards FPV heaven....cheers for the advice again, Ed