Correct tuning procedure

[ArchmageAU]

Hows the CoG (center of gravity) on your heli? Should be directly down the main shaft when batteries in place.

If the elevator is running hot, most likely the FBL is having to work the elevator harder to position against bad CoG. In this case, the elevator servo is doing twice the job of the other 2 cyclic servos.

Easiest way to test CoG is to hold the heli up horizontal to the ground as spin the fuse and see if it wants to settle tail or nose down. The head assembly, main shaft bearings, etc.. are designed to hold this position (think tic-toc).

The other way to test CoG is to lift the heli by placing 2 fingers under the grips and see if it tilts backwards or forwards.

I assume it still hovers OK.

[rhodesengr]

Originally Posted by brancoli

I find my elevator servo (120ccpm elevator at the back) always runs hotter?

I think someone else had a long thread about the same thing within the last few months. I don't remember if they ever found the root cause or posted a solution but it might be worth looking back for it.

[KSHeli]

Originally Posted by brancoli

Hi everybody

Any idea? I find my elevator servo (120ccpm elevator at the back) always runs hotter?
Anything relate to Demon tuning?
Btw, they are 3 Futaba 172sv servos on DiaboloS.
I find the rear servo hotter while maiden, hovering it naked without fuse.

Branco

I'm that won't be due to the BD3SX.
Servo hotter, measure the temp, I had one get so hot is caused the system to brownout and cause a tip over. Found out 2 servos were just worn out or damage in crashes during the previous ownership. Could also be you are just working that servo more.
Look for either a binding issue in relation to the elevator servo or else the servo may be going bad.

[Tapgorup]

Hi all, thanks for this great information. I am set to fly my maiden flight tomorrow, so was looking for a procedure as I was not clear which to start field tuning first, head or tail. So this is very helpful.

Also, wondering, as I am a little confused about the preset files. Should these be adjusted prior to my maiden flight? I downloaded the latest firmware from BD so hoping that initial settings should suffice. I have a DX 7 gen 2, set the head gain to initial 55 and tail gyro on a 3 switch, also set at 55, 65, 75. After reading a few posts, I'm going to change tail to 55, 60, 65 for first run.

However, a little confused how to do real time tuning for the Attitude holding range from 8 to 12? Also, for the download preset files, are the printed values in thread #35, the only changes in the software for set up?

Then once all is set up in the field. Set head gain as a specific value in the soft ware and then set up Rigid, Captain Rescue, Horizon, etc.

[KSHeli]

Using 500 presets on my G380, head gain 55 and tail now is at 62. On aileron rolls and coming back onto positive collective I get a real hard tail wag. I've had tail down to 53, but then the tail doesn't hold on positive collective pitch pump and the heli still shudders hard on the aileron roll.
Need suggestions, as I thought the tail boom was going to blow off this morning, its not as bad at low hs, but horrible on high hs.
With head gain at 53 the tail shudders but not near as hard. I haven't had this problem before.

[Thorvald]

Originally Posted by ArchmageAU

Hows the CoG (center of gravity) on your heli? Should be directly down the main shaft when batteries in place.

If the elevator is running hot, most likely the FBL is having to work the elevator harder to position against bad CoG. In this case, the elevator servo is doing twice the job of the other 2 cyclic servos.

Easiest way to test CoG is to hold the heli up horizontal to the ground as spin the fuse and see if it wants to settle tail or nose down. The head assembly, main shaft bearings, etc.. are designed to hold this position (think tic-toc).

The other way to test CoG is to lift the heli by placing 2 fingers under the grips and see if it tilts backwards or forwards.

I assume it still hovers OK.

Confused by your term horizontal and nose/tail down... Do you mean told the heli by the head parallel to the ground or perpendicular to the ground?

Thanks

[KSHeli]

Originally Posted by Thorvald

Confused by your term horizontal and nose/tail down... Do you mean told the heli by the head parallel to the ground or perpendicular to the ground?

Thanks

He means grasp the head and hold the heli with mainshaft parallel to the ground and rotate the heli and see how it wants to stop. May rotate then want to rotate back or forward to let the heavier end down. It should stop pointing in random direction COG is found.

[ArchmageAU]

Originally Posted by Thorvald

Confused by your term horizontal and nose/tail down... Do you mean told the heli by the head parallel to the ground or perpendicular to the ground?

Thanks

Originally Posted by KSHeli

He means grasp the head and hold the heli with mainshaft parallel to the ground and rotate the heli and see how it wants to stop. May rotate then want to rotate back or forward to let the heavier end down. It should stop pointing in random direction COG is found.

Yes. KSHeli confirmed correctly. Head held parallel to ground.

The CoG of a heli is supposed to be somewhere along the main shaft. If the main shaft is parallel to the ground, then the actual CoG of the model will try to rotate to be beneath it. If the actual CoG of the model *IS* in the main shaft, then the model will stop rotating at a random point when gently rotated in this orientation.

[DEMONjoe]

What I do is not rotate it in that position, but, holding the heli away from me, get the tail to 10:00 and 03:00, then simply let go. In both positions it should not move but simply hold the position. Then the CG is perfect.
If it drops from the 10:30 position, it's tail heavy. If it climbs from the 03:00 position, it's nose heavy.

This applies for a clockwise spinning rotor. For anti-clockwise rotor, swap my explanation

[Thorvald]

Thanks everyone, great info!

[Mr iceman]

Originally Posted by KSHeli

Using 500 presets on my G380, head gain 55 and tail now is at 62. On aileron rolls and coming back onto positive collective I get a real hard tail wag. I've had tail down to 53, but then the tail doesn't hold on positive collective pitch pump and the heli still shudders hard on the aileron roll.
Need suggestions, as I thought the tail boom was going to blow off this morning, its not as bad at low hs, but horrible on high hs.
With head gain at 53 the tail shudders but not near as hard. I haven't had this problem before.

I have a G380 with a BD3sx, it took me ages to get the tail correct, I then switched to a 3 blade head, which then took a further age to get the tail correct. I would either experience drift, with the gain at arond 50-53, or wagging and shivering if the gain was set higher. Subjectively, it seemed to be worse inverted and during aileron flips.
Have you experimented with the P-Gain? I reduced mine incrementally, I now have it set at 11. This allowed me to increase the gain and thus get a more stable, locked in tail. I have my hold power set to universal, and delay set to 4.
Do you have any 'torque compenation' set? this can upset the tail during collective inputs I have mine at 3, which helps hold the tail without upsetting it.

Cheers
Scott

[KSHeli]

Originally Posted by Mr iceman

I have a G380 with a BD3sx, it took me ages to get the tail correct, I then switched to a 3 blade head, which then took a further age to get the tail correct. I would either experience drift, with the gain at arond 50-53, or wagging and shivering if the gain was set higher. Subjectively, it seemed to be worse inverted and during aileron flips.
Have you experimented with the P-Gain? I reduced mine incrementally, I now have it set at 11. This allowed me to increase the gain and thus get a more stable, locked in tail. I have my hold power set to universal, and delay set to 4.
Do you have any 'torque compenation' set? this can upset the tail during collective inputs I have mine at 3, which helps hold the tail without upsetting it.

Cheers
Scott

I'm still trying to get mine set, on 2 blade head, I've dropped head gain to 53 and have tail gain at 52 and the shuttering on aileron role has just about disappeared. Revo-mix at 2 right now and I still have a slight tail kick on hard collective, I'm trying to find the right tail-gear gain before really messing with the revo-mix. Right now mainly trying to have some fun flying after a long winter and windy spring, so I make one change and then fly 3 packs in the evening. I also haven't engaged the Gov in my HW 50A v3 yet.

[KSHeli]

Hey guys, I just converted my Goblin 700 to gas using a trm 300 special edition and now the heli starts rocking for and aft on elevator, any recommendations to correct this.

[F1 Rocket]

Most likely picking up a vibe from the engine. Try different mounting tape. Maybe two layers of VHB.

[sjsmith8688]

Can anyone post the contents of these files in a non-HCX format, or just copy/paste them into a Reply?

I cannot open the HCX files.

Any help appreciated.

[TRex700MRX]

Are the files on the first post still good to use?

I am getting ready to install a 3SX on a 450 and just making sure.

Thanks, Dennis

[KSHeli]

Yes, these are still up to date.

[gtruk]

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