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Sep 19, 2019, 07:58 PM
Registered User
Quote:
Originally Posted by danong
1st of many steps towards maiden. Surprised by EPS quality.
Replacing all the stock 9g servos. Lot of cutting and crimping. And thanks to SU-4ever build video, i got the Turnigy Ubec.

Is the stock 17g metal gear? I read somewhere that it is. Does that need to be replaced too?
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Sep 20, 2019, 10:22 AM
JohnVHRC
JohnVH's Avatar
Quote:
Originally Posted by danong
Wow! That take off was really short. This is your 2nd flight so i guess u still on stock?
My 2nd flight, the plane I got used, it has upgraded motors and escs
Latest blog entry: Eflite Habu 32x!
Sep 20, 2019, 04:49 PM
Flying Hazard
SU-4ever's Avatar
Quote:
Originally Posted by danong
Replacing all the stock 9g servos. Lot of cutting and crimping. And thanks to SU-4ever build video, i got the Turnigy Ubec.

Is the stock 17g metal gear? I read somewhere that it is. Does that need to be replaced too?
You're welcome!!

IMO, regardless of stock taileron servos being full metal or not (depends on version), they are the most important couple to replace, as the aircraft's behavior is mainly dictated by the tailerons and you want these to run as smoothly, precise and reliable as possible

It appears that the TGY-306G servo that I reccommend has been discontinued.
Possible suitable replacements are KST DS215MG and TGY DMC809 but I have not tested them yet...
Sep 20, 2019, 05:27 PM
Registered User
Quote:
Originally Posted by SU-4ever
You're welcome!!

IMO, regardless of stock taileron servos being full metal or not (depends on version), they are the most important couple to replace, as the aircraft's behavior is mainly dictated by the tailerons and you want these to run as smoothly, precise and reliable as possible

It appears that the TGY-306G servo that I reccommend has been discontinued.
Possible suitable replacements are KST DS215MG and TGY DMC809 but I have not tested them yet...
SU-4ever,

In your build video, i see that only the 3 vectors are connected to the EagleTree gyro while the tailerons and rudders are connected direct to the receiver. Does that means the ET gyro can level(2D mode) and hold heading (3D mode) just by moving the 3 vectors, irregardless of movements by tailerons n rudders?

I am looking into purchasing the ET but confused on the servos connections. If the tailerons n rudder are not connected to the gyro, wouldn't they unstablise whatever stabilisation the ET gyro is trying to do?
Sep 20, 2019, 09:07 PM
Flying Hazard
SU-4ever's Avatar
Quote:
Originally Posted by danong
SU-4ever,

In your build video, i see that only the 3 vectors are connected to the EagleTree gyro while the tailerons and rudders are connected direct to the receiver. Does that means the ET gyro can level(2D mode) and hold heading (3D mode) just by moving the 3 vectors, irregardless of movements by tailerons n rudders?

I am looking into purchasing the ET but confused on the servos connections. If the tailerons n rudder are not connected to the gyro, wouldn't they unstablise whatever stabilisation the ET gyro is trying to do?
First, there's a couple of things you are mixing up.
2D mode is an auto-level function. If you don't touch the sticks it tries to balance the aircraft level to the horizon. DO NOT USE THIS MODE!
Not a good idea, will give you troubles most likely!
In 3D mode you have several options. Normal 3D is like a rate gyro, for each amount of rotation detected, the gyro compensates another certain amount, regardless of whether this totally cancels or not the original deviation. Heading hold on the other hand, 'approximately measures' the actual deviation and keeps forcing the control surfaces to reach original state (This is how 3D heli tails are controlled). Heading hold can have some uses but I do not reccommend it as default.

You should get the gyro 'mode' lead on a spare channel with a 3 position switch and configure it using a PC so that it can be OFF - Normal 3D - HH 3D.

Also I use the 'direct rate' function for normal 3D.
Basically I switch between off and normal 3D, and that's all I use, leaving HH for further testing in the future when I install more powerful motors, as it could help attain a more stable hover / sustained extreme high alpha.

Then you need to fine tune it to your needs. The master gain is set through a separate channel ( I think you could extend the limits of the master gain in the PC setup or something like that ) and you can fine tune axis by axis stabilization using knobs on the controller unit. The direction of correction is also set on the knobs. Full CCW would be -100%, center would kill the correction in that axis and full CW is 100% weight on the opposite direction. But in essence, the TV response is so slow that you can set the gain almost to maximum without fear of oscillations, and even then, it won't keep your aircraft locked, just ease the pilot workload. Too much gain on TV yaw may make your aircraft feel weird on turns, so an idea would be to manually lower the yaw gain so it doesn't make the jet feel clumsy and max out the rest (pitch-roll) both in the knobs and master gain. Right now though, I haven't finished fine tuning and I use like full 100% on the knobs and master to something like 65-75%.
Also, as good practice, I never turn on the gyro until the plane is in the air to avoid surprises during take off... at least until the unit is proved and you build some confidence in it. Then I turn it on AFTER setting the aircraft in the runway ready for take off and NEVER in HH. If the gyro starts in HH the nozzles will likely be mad pointing in random directions by the moment you want to take-off, be careful!

In any case, read thoroughly the manual and take an afternoon to set it right with your computer. You want to be familiar with how the thing operates

As for gyro fighting the plane, not really. When you make an input (for instance, pull up), this order is fed directly to the plane's control surfaces AND to the gyro. The gyro in turn will take this 'up' command as a setpoint (let's say, angular turn rate) and will deflect the nozzles in turn, more or less in order to match this setpoint of slower/faster turn rate according to the stick. Sticks centered means angular rate of 0/s in all axis, thus the plane tries to keep its current attitude. Mind that the channel outputs to the gyro need to be detached from trims and exactly centered at 1500us pulse when the sticks are centered so they don't mess things up! (Otherwise they will try to push the plane off of level flight with sticks centered!)
And the gyro has to be callibrated.

In any case they won't be fighting your inputs, but of course will contribute differently from what the rest of control surfaces do. If you want maximum rotation rate in any axis, when your stick command goes to full, it overrides the gyro and the nozzles will just deflect to maximum. When your sticks are centered, then all control surfaces will be still except for the nozzles that will be working to make the plane fly straighter. But I already warn you that normal wind turbulence is much stronger and short-period reaction than what the gyro does with the nozzles, so you will keep seeing the plane bump in the air. The actual point of the nozzles is making the jet behavior more predictable when you exit post stall maneuvers at near zero speed, or in sustained high alpha maneuvers. Hope this helped understand better how the thing operates

Also finishing the maneuvers is rather easier as many post-stall maneuvers depend on making the jet turn with high rotation energy over its own axis. When you want to stop this motion, without gyro the plane usually overshoots or doesn't stop where you want. With the gyro on nozzles it's easier to control the final attitude of the aircraft... and even though it takes some getting used to and skill.

Cheers, and have fun!

Always test maneuvers at a safety altitude!
Last edited by SU-4ever; Sep 20, 2019 at 09:35 PM.
Sep 21, 2019, 06:55 AM
Registered User
Su-4ever,

Thanks for your writeup! I am still confused but no worries.
This is my 3rd edf and my 1st thrust vector edf so give me some time

I was actually looking at the 2d mode for maiden flight because i just want to take off, do a few circles and land, nothing fancy. I thought auto levelling would make this much easier?

I also looked into the Hobby Eagle A3 Super 3 gyro.....That seems a better and cheaper gyro?
Sep 21, 2019, 08:20 AM
Flying Hazard
SU-4ever's Avatar

su-4ever


Not sure that's a better gyro but can't tell as I have not tried it. And in any case 2D is a bad idea. Please don't do that. If you go that route, better hook the gyro to the tailerons, but then for total different reasons and with a totally different outcome. I would strongly advise against it. In particular, for maiden flight and following flights the gyro should be turned off completely so you can properly and correctly fine tune the aircraft. The gyro at this point would only mask potential problems with the aircraft setup or add problems of its own.

Using 2D mode also forces you to fight the plane. That's not how jets are flown. Better not go that route IMO, this is not an hexacopter in ATTI mode
Oct 07, 2019, 03:11 AM
Registered User
Guys, my alierons, rudders, elevators and VT servos are all digital servos, will the sequencer and 3 retracts ok with the higher frequency sent by the receiver?
Oct 07, 2019, 10:45 AM
Flying Hazard
SU-4ever's Avatar
Long overdue... NADYA'S BACK!!!

Su-35 FPV is Back!! - HD 60fps (8 min 34 sec)


@danong I think they will be okay. I also use digital servos without problem, have you done anything specific to the receiver so it works at a different frequency? Or did you just install digital servos?
Oct 07, 2019, 12:26 PM
Registered User
Quote:
Originally Posted by SU-4ever

@danong I think they will be okay. I also use digital servos without problem, have you done anything specific to the receiver so it works at a different frequency? Or did you just install digital servos?
I have the option of setting 11ms frame rate which i think translate to almost 100hz. This is ok for digital servos but not ok for analog servos. Analog runs at 50hz if i am not wrong and 100hz will cook them. I am not sure if 100hz will cook the sequencer and/or retracts too? This is not my 1st edf but it is my 1st retracts edf hence my question.

Btw, i opened up the stock 17g elevator servos to check its insides. The gears seems to be full metal for anybody wondering. I forgot to take pictures. Anyway i already ordered the DMC809, but they are in transit somewhere in China.

I had cut the new hatch and side access like in your videos. Brillant idea!
Oct 07, 2019, 12:41 PM
Flying Hazard
SU-4ever's Avatar
Glad you took advantage of that!
It makes life that much easier!

As for the Rx, I have no experience with running them at greater Hz, so better wait for the opinion of someone else. Yes, the gear could fry if it doesn't like faster update rates. Let's see if someone has tried that yet... what receiver are you using?
Oct 07, 2019, 06:30 PM
Registered User
Quote:
Originally Posted by SU-4ever
Glad you took advantage of that!
It makes life that much easier!

As for the Rx, I have no experience with running them at greater Hz, so better wait for the opinion of someone else. Yes, the gear could fry if it doesn't like faster update rates. Let's see if someone has tried that yet... what receiver are you using?
I would like to stick to one tx so i will be using spektrum receiver but undecided which yet but they all support the faster frame rates meant for digital servos.

I attached pics of the ele servo. They looked full metal to me. Can anyone tell if they are digital by looking at the circuit board which i also attached?
Oct 07, 2019, 06:54 PM
Registered User
It looks to be digital... seeing the IC is quite 'big' (many legs/IO).
Maybe a better test is its 'buzzing' seeing digitals correct to a tighter band and thus the motor is driven much more (usually). That can be a clue.... and Analogues will pretty well be dead quiet in most cases. Maybe slight pressure on the output can help cause that buzzing occur so you can tell better...

Retracts are OK with higher refresh frequencies....
It is not that the frequency is 'higher' to cause problems in servos, it is the fact they are 'corrected' more often = more motor use = hotter and that higher heat level builds up more and more (versus cooler running).
So seeing a retract does NOT operate at all, except for the single time per signal end point ever used.... they are fine.
If you can think about any given item/device, and whether it is a 'one off' operation sort of thing, or not, then you can work out if higher frequency refresh will matter to it. The circuit itself doesn't 'care'.
Oct 07, 2019, 09:27 PM
Flying R/C since 1964
kallend's Avatar
Quote:
Originally Posted by danong
I would like to stick to one tx so i will be using spektrum receiver but undecided which yet but they all support the faster frame rates meant for digital servos.

I attached pics of the ele servo. They looked full metal to me. Can anyone tell if they are digital by looking at the circuit board which i also attached?
Spektrum Radios only send 11ms data to the 4 primary flight controls. The rest are still at 22ms.

I suggest you follow the Spektrum radio threads.
Oct 08, 2019, 03:14 AM
Registered User
The DMC809 servos just came in. I let the pics do the talking. My only concern is the arms are a lot smaller n felt weaker than the stock.


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