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Compass 7HV, 7HVU and Chronos Compass Compass 7HV, 7HVU and Chronos Model Helicopter Discussion |
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07-21-2014, 03:59 PM | #1 (permalink) |
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Join Date: Dec 2013
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elev bobble with sk540
Looking for a little help with tuning my 7hv and sk540. Ive tried raising and lowering hiller decay, hiller gain, damping gain, bell gain and all of them in combination. I completely understand how to tune a sk540 (done it multiple times) but I cant get rid of a bobble / porpoising on the elevator axis.
Its not really there when i give cyclic jabs at a hover, but if I have forward airspeed and I pump the collective stick it porpoises really bad. It will also wobble on the elevator axis if I give cyclic elevator jabs with forward airspeed. Dampers are new and elevator tail drag comp is set correctly. CG is also spot on. Ive run out of things to change. Starting to think the design of the dampers are just too soft and kinda give a spring action between the rotor head and the heli. Or maybe just trade my sk540 for a vbar and try that out. Anyone else have this issue? |
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07-21-2014, 05:47 PM | #2 (permalink) |
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Join Date: Feb 2011
Location: Australia
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There is nothing wrong with the heli or the dampers...Its the 540 you have on it, it just needs to be tuned. But in saying that consider;
What HS are you runnning? What cyclic pitch and collective are you running? The dampers are hard and need wearing in. about 20-50 fllight depending on your style. hope this helps
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Rapid Helis Australia |
07-21-2014, 06:07 PM | #3 (permalink) |
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Join Date: Dec 2013
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I'm running 1950 and 2200 headspeed. 8 or 9 degrees cyclic and 12 degrees collective. Sk gov is working great
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07-21-2014, 08:31 PM | #4 (permalink) |
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It's a known issue on some helis with skookum controllers.
From my understanding it is dealt with in the next firmware revision.
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Jeti DS-16, Oxy 3, Goblin 380, 500, 630, and 700 competition, Airwolf 600 scale heli, Brain/Ikon 2, Spartan VX1e, Sk 720, YGE and Hobbywing. |
07-22-2014, 12:39 AM | #5 (permalink) |
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Join Date: Dec 2013
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I'll hang onto it for this next update then.
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07-26-2014, 07:21 AM | #6 (permalink) |
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Join Date: Apr 2004
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I also fly the sk540 on my 7hv and it has been challenge to tune. It took me about a half dozen to get about 90% tuned in on cyclone blades.
Now I have changed to halo blades tuning has taken a lot longer. But love the blades. So maybe try a different blade it may work better for your setup. |
07-26-2014, 10:14 AM | #7 (permalink) |
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Thread Starter
Join Date: Dec 2013
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I'm still using the stock compass blades. But I was thinking about a set of rails. I've heard they are really stable so they might help the sk hold better. Anyone have a set they wanna trade or sell?
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07-26-2014, 11:06 PM | #8 (permalink) |
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Join Date: Feb 2011
Location: Australia
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Stock blades are pretty stable dude...They are very good
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Rapid Helis Australia |
07-27-2014, 12:48 PM | #9 (permalink) |
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Join Date: Apr 2010
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elev bobble with sk540
Can you tell me what tx gain you have for cyclic?
Also screen shots of your cyclic bank and servo travels. Hang tight, this should be easy. Sent from my iPhone using Tapatalk
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Oxy 3 SK540 Minijazz 20 / WARP 360 SK540 Koby 55 / Goblin 500 SK540 jive 100 / 6HV ultimate Helijive120 SK540 / 7HV SK540 Kosmik200 / Futaba18mz / Skookum support rep |
07-27-2014, 01:19 PM | #10 (permalink) |
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Thread Starter
Join Date: Dec 2013
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Tx gain 95 for both but I've tried everything thing from 50 tx gain to 100 as well as 30 hiller gain to 70 hiller gain with different tx gains.
I've tried high hiller with low damping gain and high damping with low hiller. If both are increased the bobble gets worse. One of them has to be low but that makes the heli feel sloppy and lose in the air. Doesn't stop consistently |
07-27-2014, 03:56 PM | #13 (permalink) |
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Thread Starter
Join Date: Dec 2013
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I have been thinking, could it be my servos are too slow causing the fbl unit to over correct?
Im using the MKS MKS HBL665. The specs look good to me |
07-27-2014, 05:38 PM | #14 (permalink) |
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Join Date: Apr 2010
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elev bobble with sk540
Woah, sorry to say but your settings are way way off here.
Is your unit powered up and tx on with these pics too? Showing tx gain at 15% What type of flying are you doing?
__________________
Oxy 3 SK540 Minijazz 20 / WARP 360 SK540 Koby 55 / Goblin 500 SK540 jive 100 / 6HV ultimate Helijive120 SK540 / 7HV SK540 Kosmik200 / Futaba18mz / Skookum support rep |
07-27-2014, 05:39 PM | #15 (permalink) | |
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Quote:
It's the skookum. Just give it the new upcoming skookum firmware.
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Jeti DS-16, Oxy 3, Goblin 380, 500, 630, and 700 competition, Airwolf 600 scale heli, Brain/Ikon 2, Spartan VX1e, Sk 720, YGE and Hobbywing. |
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07-27-2014, 05:39 PM | #16 (permalink) |
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Join Date: Dec 2013
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No I didn't have my tx on. That's why it's showing 15.
I fly mild to hard 3d |
07-27-2014, 05:48 PM | #17 (permalink) |
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Join Date: Apr 2010
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elev bobble with sk540
Ok. Set tail drag comp back to default -6
Take hiller decay to 140 Hiller gain to 50/50 Damping gain to 10/12 Bell gains 55/55 Tx gain to 45 for cyclic Make sure the kbdd lime green dampers are really well covered in white lithium grease With your cyclic acc at 20 you will find it sluggish on tic tocs. Up this till it responds the way you like it. That's exactly how mines set up and it's solid.
__________________
Oxy 3 SK540 Minijazz 20 / WARP 360 SK540 Koby 55 / Goblin 500 SK540 jive 100 / 6HV ultimate Helijive120 SK540 / 7HV SK540 Kosmik200 / Futaba18mz / Skookum support rep |
07-27-2014, 05:51 PM | #18 (permalink) |
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Thread Starter
Join Date: Dec 2013
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Thanks. I'll give it a shot.
My dampers are new but I installed them only with soap and water. |
07-27-2014, 05:58 PM | #19 (permalink) |
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Join Date: Apr 2010
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elev bobble with sk540
And that will only compound the problem, and make it very hard work for any FBL unit. I spread white lithium grease ( boto lube ) around the inside of the grips where the dampers go, and all over the dampers, inside and out. Then push the shaft through ( usually pops a damper out ) easy to push back in once greased
Clean and grease out of the end of the shaft with a ear bud doused in thinners. Also make sure the thrusts are the correct way round.
__________________
Oxy 3 SK540 Minijazz 20 / WARP 360 SK540 Koby 55 / Goblin 500 SK540 jive 100 / 6HV ultimate Helijive120 SK540 / 7HV SK540 Kosmik200 / Futaba18mz / Skookum support rep |
Tags |
7hv, bobble, sk540_elev_bobbing, wobble |
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