3 gyro, flybarless SR

[helibadger]

Having a couple of spare gyros lying around and being impressed with how stable my T rex 500 was after converting to flybarless, I decided to experiment on my poor little SR to see if adding gyros could make it more stable.
I hooked up the Ail and Elev servos to the 2 spare HK401 gyros and having only 6 channel stock RX I joined the 2 gain wires with a Y lead and set DX6i gyro setting to rate mode (35%). I then resurrected the old eflite stock gyro to use on the tail as it allows the HH gain to be set on the gyro, unlike the 401s. I'd like to have kept the much better HK401B on the tail but would need an extra channel to allow gain adjustment, ideally 2 more channels as the Elev and Ail gyros really should be set independently.
At first I tested out the heli with the flybar on as the purpose of the additional gyros was to act as a stabilising aid to make the heli more stable. First flight was interesting, too much gain on all 3 gyros, I had 3 axis wagging . I got it set up so it was more stable but I wouldn't say it was much better than just having the flybar with all the weights out, so in that respect I'd have to say mission failed.
I gave up on the idea and decided to ditch the flybar, leaving just a bit of the rod in to keep the paddle attached to the head. I also removed the bell mixer arms and attached the swash links direct to the blade grip using a ball link off my recently departed B400.
After a bit of setting up swash links etc , I gave it a test flight. Talk about being twitchy, the removal of the bell mixing arms got rid of 90% of the slop in the head and I had to add 20% expo to calm things down a bit, normally I have no expo.
I couldn't really give the SR a decent test as the weather is poor, 30mph wind and rain but hopefully I'll get another session later this week if the weather improves.
I think it may be too fast/twitchy for me but I'll give it another go before probably putting the flybar back on.

[Copter64]

What flybarless controller are you using?
I thought that Usually one would turn-off the CCPM (swashplate) mixing on your TX because the flybarless controller needs to do it on-board the heli.

What part of the system is providing the CCPM mixing?

You say Aileron and Elevator servo, but the SR uses 120-degree arrangement not discrete servos (as with mechanical mixing). does the 401 gyro do the mixing for the 120-deg swashplate movements?

I don't understand how this works please explain.

[helibadger]

No FBL controller, I have left the swash mix in TX. I'm not sure myself how its working or if it will fly well at all, I suspect once I get to an open area for a decent forward flight it could all end badly. All I have done so far is hover due to the weather, I know it doesn't like the wind.

I would like to try my BeastX on it but I don't know if the head geometry would work out - and other than doing the belt tail conversion I'd still have to keep the seperate tail gyro.
I was just bored really with the weather and started tinkering with things I really don't know enough about

[ame]http://www.youtube.com/watch?v=TFjy3dxjJ18[/ame]









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[Copter64]

The SR is not setup to work that way. It requires 120 deg CCPM mixing.
Even though the receiver is labeled "aileron" or "elevator" servo, that is not the function they provide. All 3 servos must work in concert to tilt the swashplate front/back(elevator function) or left/right (aileron) it is not up to any one servo. Your TX is not sending Aileron/Elevator/Pitch signals to the receiver, it is sending a 120-deg CCPM signal for coordinated movement of the swashplate (because as you said you still have CCPM turned On in your TX).


You are on the right idea of using heading-lock gyros but in that case you need some sort of CCPM mixing (electronic or mechanical) AFTER the heading-lock gyros, not before (not on your TX).
This is similar to what the scale-flyers used to do before integrated flybarless controllers, but in that case they had mechanical CCPM mixing on-board the Heli.

The gyros will get confused because the singal that comes-in on the RX's Aileron and Elevator channels are actually mixed-in with coordinated swashplate movements.

[helibadger]

Thanks for that, I knew I was missing something and was surprised it actually flew reasonably well. I did try the 2 gyros in HH mode and almost shook the SR to pieces.

I may just scrap the test flights before I wreck the little guy. Pity, because it felt like it had a bit more power without the flybar and sounded better. I may try the BeastX on it anyway.

[Copter64]

helibadger:
I would really like to know more about how you were able to link from swashplate to the blade-grips directly. I would like to try eliminating the flybar and mixing-arms from my Flymentor setup as an experiement.

You said it was Blade 400 parts? which ones and what modification did you have to do to the B400 parts / SR blade grips?


One problem I am worried about is making sure the upper-swashplate doesn't just rotate away from the blade grips, I guess that's why you kept the paddle-control frames attached to keep the swash-plate in-line with the blade-grip links ?

Your picture has inspired me, I want to try it out.

[John Shipley]

Good Work!!! Mary Shelly would be proud of you........she wrote, Frankenstein.....J

[fusionsx00]

Well as soon as I get funds to get a trex 450 fbl head, swap out my bearings for a 5mm main shaft, find one more ds 410 servo, and get a hold of a sk360 fbl controller, the sr will be flybarless, I have the trex grips already, made spacers to hold the sr blades
im looking for 2nd hand parts, as the new head is way too much cost for this project.

I had to pry this sr from my sons Hands but he got a new mcpx. And he is happy.
all the dimensions are there For this to work swash balls need to be replaced on the upper but not to the servos.

I might just wait and see if blade makes a fbl head for there new 450. That might be a easier fit.

[helibadger]

Originally Posted by Copter64

helibadger:
I would really like to know more about how you were able to link from swashplate to the blade-grips directly. I would like to try eliminating the flybar and mixing-arms from my Flymentor setup as an experiement.

You said it was Blade 400 parts? which ones and what modification did you have to do to the B400 parts / SR blade grips?


One problem I am worried about is making sure the upper-swashplate doesn't just rotate away from the blade grips, I guess that's why you kept the paddle-control frames attached to keep the swash-plate in-line with the blade-grip links ?

Your picture has inspired me, I want to try it out.

I used the shorter linkage ball from B400 swash and screwed it directly into the SR blade grip. keeping the brass tube from the SR mixing arm on the grip. I used the threaded top pitch link from SR with a larger B400 plastic ball link, have to use a new one as the thread size is smaller on the SR rod, it still isn't as tight as I would like, it may be better to resize the SR ball link to fit the larger ball. Still needs more work to sort out length of links to get correct pitch set up if possible.

I had to keep the paddle control frames to act as a swash driver , not the neatest set up , a longer rotor head with space below for swash drivers would look/work better.

fusionsX00 - I like the idea of a 450fbl head transplant, sounds like some major surgery may be required though. Look forward to seeing that.
Or maybe SR PRO 2 will have FBL and belt drive and save us from this madness.

[fusionsx00]

Nope not really, pretty easy, change 2 bearings to a 5mm id.
and open the main gear to a 5mm id, that's the most difficult part.

Hell I already put a belt kit, trex 250 tail, carbon fiber body.

So 2 bearings and a opening a main gearing is nothing

[helibadger]

Originally Posted by fusionsx00

Nope not really, pretty easy, change 2 bearings to a 5mm id.
and open the main gear to a 5mm id, that's the most difficult part.

Hell I already put a belt kit, trex 250 tail, carbon fiber body.

So 2 bearings and a opening a main gearing is nothing

Doesn't sound too bad when you put it like that. Could the B400 main gear be used with a sleeve/reducer in place of the one way bearing? It's a bit thicker and heavy duty as well, maybe not a good thing if space is tight.

[TomC]

Sorry but I do not see a swash lock/driver. Whtout this, no fbl system is going to work omho.

[helibadger]

The paddle control pushrods are acting as swash lock/drivers. That's why I had to leave all the top end on with a small peice of flybar still locking it all together. I was hoping hoping to get rid of all that but can't see a way to retro fit swash links on the rotor head below the grips.
It's not pretty but seems to work for basic hovering, still no chance to get a decent flight yet.

[rudyrov]

helibager, I think this is great, neat bit of tinkering.
Question, Have you or anybody tried FBL set up without any special stabilization... For example, just the tail gyro and nothing else?
Love the work you are doing!

Rudy

[helibadger]

I haven't tried just taking the flybar off, you'd still have to cut it and leave the bit of flybar rod to keep the head in one piece. I think it would be really unstable in flight, might be "fun" to try though.

[tumble2k]

Originally Posted by rudyrov

helibager, I think this is great, neat bit of tinkering.
Question, Have you or anybody tried FBL set up without any special stabilization... For example, just the tail gyro and nothing else?
Love the work you are doing!

Rudy

This is off topic, but I tried it on an mSR. I had to rotate the swash with my transmitter, add extra travel with the Cusker mod and cutting the swash arms short. The only way to make it almost flyable was to put copper tape on the blades to weight them a lot. I think a ten-year-old video gamer could fly it but not me.

Anyway back to the regular schedule programming ... I was thinking about doing the same mod for my SR. I was puzzling out how to get the ball end onto the blade grip. I was going to cut the ball end off the mixing arm and glue it to the grip but it seemed kind of dangerous in case it broke off.

[Torquewrench]

Very interesting stuff you got going on here. I am also a flybarless only guy, have converted most of my birds. I would like to do the SR with a 400 -450 head, but don't want to blow much needed repair money for other birds on a trial experiment. Nice flying and keep us posted!!!

[helibadger]

I decided to try the B400 head on an old chassis I had lying around after fusionsx00 good ideas earlier about the main shaft bearings and main gear. B400 gear and one way bearing can be made to fit, shaft would need chopped 25mm or so.I used 5x8x2.5mm bearings, should be 3mm tall but didn't have any.
It all seems a bit top heavy though for the little plastic chassis, I think the stock motor/ESC might struggle to cope. New anti rotation bracket needed as well.
I think a lighter weight FBL head and grips would be a better option, RJX 450 type??

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.Here's a quick mock- up of how it all might look, I don't think I'll go any further with this set up for now though.
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[mrmarc]

I'm sorry for reviving this, but I'm curious if this went anywhere. There's some good info in this thread.