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waqr · 07-01-2014, 01:53 AM

Hi!

I just set up my stretched 450 Pro with ZYX and it flies awesome except for that I have this " Dolphin" effect in fast forward flight. Sudddenly the nose jumps up and down. Also when doing fast pitchpumps the nose wobbles up and down. Which parameter should I change in order to get rid of this behaviour?

Thanks!

Dr. M · 07-01-2014, 03:58 PM

Ah, the dreaded "dolphining" or "purpoising" in FFF... Lowering the Pitch total gain and/or I-gain should help. Blade selection also plays an important role in the helicopter stability in FFF - some are better than others.

waqr · 07-01-2014, 04:04 PM

Thanks!

This is my current setup. Please feel free to give advice on how much to lower each value

Dr. M · 07-01-2014, 09:42 PM

Your main gains are already kinda low. How long are your cyclic servo horns from center to link ball?

waqr · 07-02-2014, 02:49 AM

Roughly 13,5mm. Do you think I should try to increase the gains?

Nihilistic · 07-02-2014, 06:21 AM

I would suggest setting your PID gains for roll and pitch to be the same. If you set P-gain to 80 for roll, use 80 for P-gain on pitch as well. Same goes for the I-gain and D-gain. If you're using the default 100 on roll I-gain, use 100 for pitch I-gain. I would just click the Soft 3D preset and use those default values, then set your roll and pitch D-gain to 10, and see how it flies. You need to lower those to 20 or less when using FW 3.5 or later. Your RC deadband seems kind of low. I think default is like 40 isn't it? Also, you may want to grab FW 4.02, since it eliminates the FFF pitch up bug.

What servos are you using? Are they digital or analog? If they're analog, the default Soft 3D gain presets for main rotor pitch and roll of 40 may be too high. If they're good digital servos, you may be able to set them higher. What are the speed and torque specs.? You may want to move the ball links on your servo arms in toward the servo axis one hole on all your cyclic servos. Follow Dr. M's stickied tweak guide above. He suggests that your collective setting should be between 60 and 80 (+ or - depending on which gets your swash moving in the right direction) for +/- 12 degrees pitch.

What main blades are you using? Are they balanced? Got any damage?

You may need to go through set up again and make sure you got your servos all at 90 degrees at midstick and your swash is leveled. Rotor shaft is straight and no worn out head dampers or anything?

Are your servos mounted good and securely so that the cases aren't moving in their mounts?

waqr · 07-02-2014, 11:43 AM

Thanks!

I use Hitec 5065MG:s so they are digital. I have version 4.01 installed. How do I upgrade to 4.02?

Nihilistic · 07-02-2014, 08:04 PM

Here's the link to get 4.02 FW for the ZYX-S. Is yours a ZYX or ZYX-S? Stick with the FW you have if it's the regular ZYX.

http://www.tarot-rc.com/index.php?main_page=page&id=14

Here's a thread containing info on how to flash the new FW to the ZYX-S.

https://www.helifreak.com/showthread.php?t=438533

07-01-2014, 01:53 AM	#1 (permalink)
waqr Registered Users Join Date: Jan 2011	Jumps up and down in fast forward flight Hi! I just set up my stretched 450 Pro with ZYX and it flies awesome except for that I have this " Dolphin" effect in fast forward flight. Sudddenly the nose jumps up and down. Also when doing fast pitchpumps the nose wobbles up and down. Which parameter should I change in order to get rid of this behaviour? Thanks! __________________ Trex 700N (OS91 and BeastX) Trex 600N (OS55 and BeastX)

07-01-2014, 03:58 PM	#2 (permalink)
Dr. M Registered Users My HF Map location Join Date: Jun 2011	Ah, the dreaded "dolphining" or "purpoising" in FFF... Lowering the Pitch total gain and/or I-gain should help. Blade selection also plays an important role in the helicopter stability in FFF - some are better than others. __________________ CopterX 450 Black Angel FBL "Night Rig" \| ZYX v4.0 PRÔTOS 500 FBL "Sky Whip" \| Robird G31 Audacity P6 FBL "Phoenix" \| MSH Brain \| 12s Goblin Speed \| iKon

07-01-2014, 04:04 PM	#3 (permalink)
waqr Registered Users Thread Starter Join Date: Jan 2011	Jumps up and down in fast forward flight Thanks! This is my current setup. Please feel free to give advice on how much to lower each value __________________ Trex 700N (OS91 and BeastX) Trex 600N (OS55 and BeastX)

07-01-2014, 09:42 PM	#4 (permalink)
Dr. M Registered Users My HF Map location Join Date: Jun 2011	Jumps up and down in fast forward flight Your main gains are already kinda low. How long are your cyclic servo horns from center to link ball? __________________ CopterX 450 Black Angel FBL "Night Rig" \| ZYX v4.0 PRÔTOS 500 FBL "Sky Whip" \| Robird G31 Audacity P6 FBL "Phoenix" \| MSH Brain \| 12s Goblin Speed \| iKon

07-02-2014, 02:49 AM	#5 (permalink)
waqr Registered Users Thread Starter Join Date: Jan 2011	Roughly 13,5mm. Do you think I should try to increase the gains? __________________ Trex 700N (OS91 and BeastX) Trex 600N (OS55 and BeastX)

07-02-2014, 06:21 AM	#6 (permalink)
Nihilistic Registered Users Join Date: Aug 2007	I would suggest setting your PID gains for roll and pitch to be the same. If you set P-gain to 80 for roll, use 80 for P-gain on pitch as well. Same goes for the I-gain and D-gain. If you're using the default 100 on roll I-gain, use 100 for pitch I-gain. I would just click the Soft 3D preset and use those default values, then set your roll and pitch D-gain to 10, and see how it flies. You need to lower those to 20 or less when using FW 3.5 or later. Your RC deadband seems kind of low. I think default is like 40 isn't it? Also, you may want to grab FW 4.02, since it eliminates the FFF pitch up bug. What servos are you using? Are they digital or analog? If they're analog, the default Soft 3D gain presets for main rotor pitch and roll of 40 may be too high. If they're good digital servos, you may be able to set them higher. What are the speed and torque specs.? You may want to move the ball links on your servo arms in toward the servo axis one hole on all your cyclic servos. Follow Dr. M's stickied tweak guide above. He suggests that your collective setting should be between 60 and 80 (+ or - depending on which gets your swash moving in the right direction) for +/- 12 degrees pitch. What main blades are you using? Are they balanced? Got any damage? You may need to go through set up again and make sure you got your servos all at 90 degrees at midstick and your swash is leveled. Rotor shaft is straight and no worn out head dampers or anything? Are your servos mounted good and securely so that the cases aren't moving in their mounts?

07-02-2014, 11:43 AM	#7 (permalink)
waqr Registered Users Thread Starter Join Date: Jan 2011	Thanks! I use Hitec 5065MG:s so they are digital. I have version 4.01 installed. How do I upgrade to 4.02? __________________ Trex 700N (OS91 and BeastX) Trex 600N (OS55 and BeastX)

07-02-2014, 08:04 PM	#8 (permalink)
Nihilistic Registered Users Join Date: Aug 2007	Here's the link to get 4.02 FW for the ZYX-S. Is yours a ZYX or ZYX-S? Stick with the FW you have if it's the regular ZYX. http://www.tarot-rc.com/index.php?main_page=page&id=14 Here's a thread containing info on how to flash the new FW to the ZYX-S. https://www.helifreak.com/showthread.php?t=438533

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