e-copter
Senior Heliman
Location: Nice, France
| Hi,
i can see two things that could casue jumps in flight before the SK360itself :
1) Your Rx antenna runs along the tail boom reinforcements. If they are carbon, very bad. You need to separat the antenna from the carbon parts or to insulate it with silicon tube or anything that will prevent the antenna to touch directly the carbon.
2) your Sk uit is fitted right up the tail belt and it's pulley. It's possible that you get cyclic jumps when the static electricity generated by the gears and the belt ripping in the tail boom discharges .
BEfore making any further software tests, i would highly encourage you to first lube the tail belt flat area ( the one on the outside ) with silicon lube or teflon lube. Then you must absolutly route your antenna RX in another way than the one on the picture.
Then, the Mini Titan blade grips are made to work with bell paddles and are normally mimwed down by washout ant pitch mixers arms. In direct cyclic input, you need to have your servos having a correct travel ratio with the blade grips. The Titan grips will ot allow a very good flybarless control as thy are, as input is too sensitive on them like that. You need to have normally 12 mm between the center of the servo arm and the link ball on cyclic servos, and with 60% pitch travel approximatively on transmitter, you must achieve +10 / -10 on pitch and then you need to setup +7 / -7° on cyclic to have the SK360 working fine (or any otherr flybarless stabilisation system).
Finally, you need a good headspeed, more than 2300 rpm (2600 / 2700 works fine) and you must tighten the blades a little more than on bell hiller systems or the blades will go badly forward / backward and you will notice after some time that your linkages going from the blade grips to the swashplate might bend a bit because of the very bad lever effect and high torque generated by the backwarding blade. As well, when the blades go forward / backward, the entire geometry of the rotor disc control is modified and the SK unit will never be able to counteract correclty as it will correct with a dephasing around 6 or 7° sometimes becasue of the blades not beeng correctly aligned.
then, dampening on flybarless must be null or progressive. If it's existing but too tight, then you get lot of vibrations, that is why on real flybarless systems which work ( like hOf rotor heads) the main hub is very wide and you need then very progressive dampening. the wideness of the hub will help keeping soft dampeners for progressive dampening but stays tight enough for fast cyclic answer.
>The electronics, as good as it can be, will not be able to operate correctly if the mechanics does not allow it to work correct.
the last thing is that blades on the market are not meant to work with flybarless systems. The CG's are around middle of blades and should be at least 2cm further to the blade tips.
We made numerous tests with some buddies on a small flybarless heli to find all of this and once you will find the accurate mechanical adjustements, you will have to play with the blade grip control ball location by adding shims or reducing the blade grip control arm lenght to find the best delta setup ( depends on dampening, blades type and rotor head speed + swashplate diameter and pitch ratio on blade grip..).
All that said, try first to eleminate any static electricity / receiving glitches possibilities and then you can start to play with software and mechanical adjustements.
I'm waiting my SK unit to test, we have a Mini Titan Se to perform the tests and a Dragonus, we will test with normal hub / blade grips and then with a special hub and blade grips for flybarless flight and lastly with new customs blades. If anybody is interrested in teh results, we will post them here 
BEst regards,
Fabien
Too much is not enough.... |
