Fun, Learning, Friendship and Mutual Respect
START  HERE


Unregistered
Go Back   HeliFreak > R/C Electronics Support > Skookum Robotics


Skookum Robotics Skookum Robotics SK-360 SK-540 & SK-720 Digital Flybar


Reply
 
Thread Tools Display Modes
Old 12-25-2012, 01:49 PM   #21
Luvmyhelis
Registered Users
 
Posts: 9,766
 

Join Date: Jul 2010
Location: spokane,washington
Default

Sorry I didn't jump in till now. I noticed on a few helis that not only had some iffy servos for the weight/load on the cyclics that they got into the aileron wag from time to time. But also have seen issues with both softer and harder damps that do this also from a combination of feathering shaft movement (soft) and an over gain situation ( hard) . My solution was to put in some harder damps and drop overall gain. Aileron wagging totally disappeared. I also addressed a slightly loose swash and servo links though at the same time. Fore aft had no problems due to the weight bias there.
__________________
Jeti, Soko, Koll, 800Triabolo, Gob700 @ SHS800, Trex600,Chase360 Sk720B/540/360 YGE/YEP/MKS/Outrage/Turnigy RcTek Boca Herc/Gryphon/ScottGray Scorp/KDE/Kontronik Tenax Lynx
Luvmyhelis is offline        Reply With Quote
Old 12-25-2012, 06:41 PM   #22
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

Thanks for your input.

I started out with some orange KBDD dampers that were VERY hard, and trying to run a slow headspeed made this heli very difficult to even hover. The cyclic was going bonkers. At anything below 2200rpm it was essentially unflyable.

I then tried black Align dampers and that were better, but still not great. With the current grey Align dampers I have got down to 1800rpm with mostly minimal problems (in still conditions).

The issues I have now are the random wagging during FF (even in calm conditions) - not sure if this a tail issue or a aileron issue, and the sensitivity to wind where the cyclic misbehaves badly whenever there is anything more than a gentle 5-10mph breeze.

My Futaba 9650 servos have a capacity for 13.5kg between the 3, which is around 4x the weight of the heli. On my Long Ranger I have 3x Futaba BLS 252, which have a combined capacity of about 37.5kg, which is ±4x the 9kg weight of the heli (and it behaves really well), so on paper these servos should have enough torque. Some of the scale guys are using the same BLS 252 on even larger scale helis weighing close to 20kg (so less than a 2x "safety factor") without problems.

Can you give me some idea of what combination of dampers, headspeed & gain settings you had some success with ?

Thanks
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 12-28-2012, 08:39 AM   #23
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

I believe most of the problems come from the servo travel and swash mixing setup. Did you raise the servo travel and reduce the swash mixing? Wobbles are from too much too fast of an input to the head. The linkage and blades start oscillating and can't catch up to the inputs.

I had the elevator bounce and by reducing the blade dampening to 9/10 elev/ail it's pretty much gone.
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 12-30-2012, 02:50 AM   #24
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

Thanks. By blade dampening, do you mean the damping gain in the Skookum setup - ie. set the damping gains to 9 for elev and 10 for aileron ?

I have redone the head setup with slightly longer servos to try it. I now get 11° of cyclic pitch with the elev & aileron swash mixes at 60 (no yellow). I had to reduce the collective swash mix to 35 to avoid huge collective pitches. I will get out on the next day the wind isn't howling.

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 12-30-2012, 09:06 AM   #25
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

Yes, it may vary for scale heads but it calmed things down for me and this is one area you should investigate. Since I've dropped those values, I haven't turned up the overall gain to see how high I can get it without wobbles but maybe today if it's not raining.
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 12-30-2012, 09:45 PM   #26
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

I replaced the 6-arm start shaped servo arms with a 4-arm servo arm which is one hole longer (4 holes instead of 3). The ball is obviously in the outer holes.

I set up the servos with the default 125 servo travel in the Skookum, except two minor changes to get the swash level top and bottom travel.

I fitted the links from the inner swash to the blade grips on the longer swash balls to get maximum cyclic travel. I set the Collective swash mix to 30, which reduced my overall travel to a TOTAL of 20° (from -4° to +16° in my case). I then used my Tx pitch curve to reduce this to -3° to +12°.

I then set my cyclic swash mixes (elevator & aileron) to 60 (5 away from turning yellow), and this gives me ± 11.5° on aileron and ± 11° on elevator, both of which are more than the recommended ± 10°.

I got it out today for some test hovers. It was not ideal conditions as the wind was fairly strong with some fierce gusts.

Instead of trying to post logs and setup files, I started a flight log as a Word document and here is a cut and paste from the notes. Apologies for the long post;

31/12/12 – warm 28 degrees, cloudy, windy 20-35km/h

Flight 1 – generally windy with a few lulls and frequent gusts up to 30km/h


On Cyclic 2 - Cyclic gain = 45, Bell gains = 25, Hiller gains = 55, Damping gain = 17&22, Tail gain = 51, Hiller decay = 85, Cyclic accel = 12
On Cyclic 1 - Cyclic gain = 55, Bell gains = 41&46, Hiller gains = 55, Damping gain = 17&22, Tail gain = 49, Hiller decay = 85, Cyclic accel = 12
No real difference between the two. Both were unpredictable in windy conditions. Very jittery. Tail had a slight intermittent shimmy.

Flight 2 – generally windy with a few lulls and frequent gusts up to 35km/h


On Cyclic 2 - Cyclic gain = 40, Bell gains = 25, Hiller gains = 55, Damping gain = 17&22, Tail gain = 60, Hiller decay = 85, Cyclic accel = 12
On Cyclic 1 - Cyclic gain = 40, Bell gains = 25, Hiller gains = 55, Damping gain = 10&10, Tail gain = 60, Hiller decay = 85, Cyclic accel = 12
Both were quite stable in a lull in the lulls, but both unpredictable in windy conditions. Very jittery. The cyclic 1 seemed worse when a gust hit – almost uncontrollable. The tail seemed better except in very gusty conditions when it twitched more than flight 1.

Flight 3 – generally light winds with frequent lulls and a few gusts up to 25km/h


On Cyclic 2 - Cyclic gain = 40, Bell gains = 40, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
On Cyclic 1 - Cyclic gain = 40, Bell gains = 25, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
Both were quite stable in a lull in the light wind, but both unpredictable in windy conditions, although not windy enough to pick a real difference between the two. The cyclic 2 seemed slightly worse when a gust hit. The tail seemed slightly better.

Flight 4 – generally light winds with a few lulls and a few gusts up to 30km/h


On Cyclic 2 - Cyclic gain = 40, Bell gains = 40, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
On Cyclic 1 - Cyclic gain = 40, Bell gains = 25, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
Both were quite stable in a lull in the light wind, but both unpredictable and twitchy in windy conditions. The cyclic 2 seemed slightly worse when a gust hit. The tail still twitched in the gusts.

Flight 5 – generally windy with a few lulls and a few gusts up to 30km/h


On Cyclic 2 - Cyclic gain = 40, Bell gains = 40, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
On Cyclic 1 - Cyclic gain = 40, Bell gains = 20, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
Both were quite stable in a lull in the light wind, but both unpredictable and twitchy in windy conditions. The cyclic 2 seemed slightly worse when a gust hit. The tail still twitched in the gusts.

Flight 6 – generally windy with a few lulls and frequent gusts up to 30-35km/h


On Cyclic 2 - Cyclic gain = 40, Bell gains = 40, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
On Cyclic 1 - Cyclic gain = 40, Bell gains = 20, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12
Both were unpredictable and twitchy in windy conditions. The cyclic 2 seemed slightly to respond quicker with smaller inputs when a gust hit, whereas Cyclic 1 was slower to respond, but seemed to make bigger changes. Both were bad, but some of the big “corrections” were harder to compensate for. The tail still twitched in the gusts.

So, in summary, tried overall cyclic gains from 55 down to 40, tried Bell gains from over 40 down to 20, and tried damping gains from over 20 down to 10.

None of these resulted in a "settled" heli, and even in high gusty conditions, it was difficult to tell if Bell gains of 40 were better or worse than 20 - they were different, but neither good. I think that the overall cyclic gain of 40 was better than 55, but I'm not sure how much lower I should go with this ?

Have a great New Year.

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 12-31-2012, 08:00 AM   #27
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

Well it sounds like you have the geometry close by the sound of things, around 60 in cyclic mixing, 125 or so in servo travel.

No wobbles at all? In the head I mean, not the fuselage.
Just to confirm, this is a 2 bladed head right?

One other thing that caught my eye is collective mixing is 20 or so. At first thought, ok, it's scale you'e not going to be doing 3D. But you may need that 40-45% number in the Skookum mixing for some reason. Might try going back to the 40-45% +- 10 degrees collective and just raise the curve at the bottom to get your -5 degrees. I do that in normal rpm just for easy lazy flying.

Another item of discussion is don't be afraid to go too high or too low on the blade dampening settings. The only thing you have to be afraid of is the wobbles if they get out of control and usually that is a result of servo horn geometry. So run the blade dampening way up or down.

I've also had the cyclic accel down to 9? what ever the lowest number is.

A hiller decay of 75 should make for a very stable hover provide the rest is in order.

So overall you would call the heli twitchy?
And the rotor blades compare to the stock 500 blades how? Shorter and wider chord?

Challenging!
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 12-31-2012, 08:09 AM   #28
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

Have you reset stick scaling after all the servo travel and geometry changes?
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 12-31-2012, 12:09 PM   #29
teamdavey
Registered Users
 

Join Date: Nov 2005
Location: Sunnyvale
Default

Late to the party here but here goes. How heavy are those blades?

8 lbs is very heavy on 435s unless they are really heavy or running very fast.
__________________
teamdavey
teamdavey is offline        Reply With Quote
Old 12-31-2012, 05:26 PM   #30
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

Thanks for some good prompts.

The heli does get the wobbles when it responds to wind. Usually stays in control with some effort.

It has a 2 blade RJX FBL head with Align grey dampers & a couple of thin Atom 500 shims to tighten things up just a touch (have tried KBDD hard orange & Align black - too hard, and it wobbled badly at lower headspeeds).

The collective mixing is 30. It was 40 before the servo arm change. At 40 it gives me around ±12°, whereas at 30 this drops to ±10°.

The damping gain gain at 10 seemed to be worse (with a very short test using the other bank) than closer to 20.

I can certainly try to reduce the cyclic acceleration further.

I think I had tried the Hiller decay at around 75 some time ago, and recently pushed it up to 85. Not really sure if it made much difference.

The first blades I tried back with the orange KBDD dampers were a set of Mavrikk 430mm wide chord.

The second set were some Spin 435mm asymmetrical (almost flat bottomed) blades. They have a much wider chord - I think that stock is something like 42mm, and these are around 54mm.

The current set are 465mm Spin asymmetrical blades - same as 435mm but 30mm longer. These 465mm blades are 77 grams compared with the stock 57 grams.

I did not reset the Tx stick scaling after changing the arms - completely forgot about that - thanks.

I think I would struggle to get enough lift at 1800rpm with stock Align 425mm (42mm chord & 57grams) for the added weight of the fuselage. The 465mm Spin blades are nearly 10% longer (but makes a big difference at tip diameter), 29% wider (with a almost flat bottom, so heaps more lift) & 35% heavier than Align 425mm.

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 01-01-2013, 08:52 AM   #31
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

Reset stick scaling and try it again. If things remain the same then you might need to go back in one hole on the servo arm. Wobbles are are sign of too much mechanical gain and not having worked with scale models, I would guess that rpm definitely has an effect there also. Try resetting everything back to scale on the cyclic tab. Set in 50 on overall gain and 75 on hiller decay. Notice that between scale and 3D settings the only real thing that changes is hiller decay and accel. I really think it needs to be set up with full +- collective and then dial it out with the Tx curve at the low end. Set in the baseline 60/60/45 mixing numbers and adjust the ball / servo travel from there. I also found that the gel mounting method is a little too soft.
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 01-05-2013, 07:03 PM   #32
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

Thanks.

I checked the stick scaling and it was fine (which, I think, makes sense as I did not change anything relating to the Tx, but rather just increased the amount of overall swash movement from the same amount of servo travel). I did re-do the scaling anyway as a precaution.

Going back in one hole takes me back to where I was with the previous servo arms, and I would need to increase elevator & aileron swash mixes up to around 60 again to get back close to ± 10° cyclic pitch.

I tried resetting one bank back to scale - right-click Reset to Scale. More detailed notes below, but it made things even more twitchy, possibly due to the Scale default having the same 200+° in control rates as the 3D defaults.

Essentially my method of setting scale pitch range is to change the length of the swash to blade grip linkage to get a positive pitch (around 4-5°) at centre stick rather than 0° pitch at centre stick. I then shorten the pitch curves in the Tx (sometimes both ends) to give me the range I want.

The only thing I have done differently here (and it may have an affect, I don't know) is to reduce my overall pitch range (before adjusting Tx curves). At a collective swash mix of around 40-45 I would get an overall pitch travel of around 26° (usually a bit more at 45) (whether this is -13° to +13° for a 3D setup, or -6° to +20° for my setup probably doesn't matter).

I then have two choices;

1. Reduce the collective swash mix (i have been told by Art, and I think Georgi) previously that around 30-35 is acceptable, but not lower than this) to get an overall pitch range closer to 18-20°, and then fine tune using the Tx pitch curves to get back to -3° to +12°. This still gives me a pitch curve with something like 0-80%.

2. Leave the collective swash mix around 45, and just use the Tx pitch curves to reduce my overall pitch range back to -3° to +12°. This may mean that I would have Tx pitch curve something like 15-60%.

To me, option 1 seemed better, but perhaps there is nothing wrong with doing it all in the Tx. Interested in others comments ?


Here are the flight notes and Skookum parameters from recent flights. It was a bit too calm to get really noticeable wind affects, but I did notice a few things;

1. The default scale settings had fairly vicious control rates (same as 3D), which made it twitchy.

2. A cyclic gain of 35 with Bell gains of 40 seemed too "mushy"

3. Even after reducing the control rates (the only change I made from default) in the scale defaults (which automatically reduced the Bell gains to around 24), it was still more erratic than my other bank.

4. I turned off the logging completely and it did not make any difference at all - at least not under these fairly calm conditions. The cyclic was still twitching/wobbling around uncommanded.

5. I think that my tail gain of 55 was overgained, and I think this may have caused some of the side-to-side movements in FF. In flight 5, I nearly lost it because it started thrashing around by about 30° each way just as I was about to start a big banked turn at the end of the field. The tail was not wagging at all in hover, so it was not obvious that gain was too high.

6. My last flight was fairly uneventful (but conditions were calm), so I will try these settings the next time I get out.

7. It may be worth noting that after these flights I flew my larger Long Ranger, which has a SK720, setup in exactly the same way (ie. pitch setup, it actually has swash mixes of - collective = 35, elevator = 75 & aileron = 74) with fairly similar cyclic parameters, and it flew flawlessly. It just lifts off and sits there waiting for an input. I do understand that it is twice the size

Flights in near windless conditions on 02 January 2013

Flight 1 – generally fairly calm with a few light gusts
On Cyclic 2 - Cyclic gain = 40, Bell gains = 40, Hiller gains = 55, Damping gain = 15&15, Tail gain = 55, Hiller decay = 85, Cyclic accel = 12, control rates = 110&110
On Cyclic 1 – reset to default scale settings. Cyclic gain = 50, Bell gains = 40&48, Hiller gains = 50, Damping gain = 18&16, Tail gain = 55, Hiller decay = 75, Cyclic accel = 20, control rates = 210 &240
Both flew OK in calm conditions, but Cyclic 1 (default scale settings) was noticeably more twitchy and erratic in cyclic.

Flight 2 – generally fairly calm with a few light gusts. Flew large figure 8s.
On Cyclic 2 - Cyclic gain = 40, Bell gains = 40, Hiller gains = 50, Damping gain = 15&15, Tail gain = 55, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – reset to default scale settings. Cyclic gain = 50, Bell gains = 40&48, Hiller gains = 50, Damping gain = 18&16, Tail gain = 55, Hiller decay = 75, Cyclic accel = 20, control rates = 210 &240
Mostly flew cyclic 2 as 1 was too twitchy. In large circuits it still twitched in FF with some erratic movements, mostly in straight FF – looked like a side to side or tail twitch.

Flight 3 – generally fairly calm with a few light gusts. Flew large figure 8s.
On Cyclic 2 - Cyclic gain = 35, Bell gains = 40, Hiller gains = 50, Damping gain = 15&15, Tail gain = 55, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – changed scale default control rates only (and this reduced the Bell gains itself). Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 55, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120
Mostly flew cyclic 2, and switched to 1 for the last few circuits. In large circuits it still twitched in FF with some erratic movements, mostly in straight FF – looked like a side to side or tail twitch. The controls felt more mushy after dropping cyclic gain to 35 – almost like nothing was happening initially when input was given. Cyclic 1 (default scale with reduced control rates) was definitely more prone to the random twitches and they were more noticeable.

Flight 4 – generally fairly calm with a few light gusts. Flew large figure 8s.
On Cyclic 2 - Cyclic gain = 40, Bell gains = 30, Hiller gains = 50, Damping gain = 15&15, Tail gain = 55, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – changed scale default control rates only (and this reduced the Bell gains itself). Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 55, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120
Mostly flew cyclic 2, and switched to 1 for the last few circuits. In large circuits it still twitched in FF with some erratic movements, mostly in straight FF, but not as much (it was almost windless though) – looked like a side to side or tail twitch. The controls did not feel as mushy as with cyclic gain at 35. Cyclic 1 (default scale with reduced control rates) was definitely more prone to the random twitches and they were more noticeable.

Flight 5 – generally fairly calm with a few light gusts. Flew large figure 8s. Turned all logging off.
On Cyclic 2 - Cyclic gain = 40, Bell gains = 30, Hiller gains = 50, Damping gain = 15&15, Tail gain = 55, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – changed scale default control rates only (and this reduced the Bell gains itself). Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 55, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120
Mostly flew cyclic 1, because the tail went crazy early in the flight in cyclic 2. Just as I was entering a RH banked turn in windless conditions the tail started swinging about 30 degrees each way. I returned to a high hover to let the uncommanded movement settle down, brought it back and switched to cyclic 1.

Flight 6 – generally fairly calm with a few light gusts. Flew large figure 8s. Tail gains reduced
On Cyclic 2 - Cyclic gain = 40, Bell gains = 30, Hiller gains = 50, Damping gain = 15&15, Tail gain = 40, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – changed scale default control rates only (and this reduced the Bell gains itself). Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 45, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120
Tail felt better with no un-commanded tail movements. The cyclic on cyclic 1 was still a bit twitchy, although the tail gain of 45 felt better than the 40 on cyclic 2.

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 01-05-2013, 10:35 PM   #33
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

First I would get rid of the gel and use a 2mm foam to the airframe metal plate and SK. I've tried all manner of mounts and the SK is pretty much bullet proof and will take the vibes and still handle well. I've had vibes up around 20 when I had motor issues. A good firm mount with no tugging from wires is important.

Second, I would go back to square one and set it up to the basic numbers in a sport/3D arrangement +-10 to 12 degrees. Take out some negative at the bottom and hit 0 degs at mid stick and fly it. See how it does. If it still is twitchy then something else is wrong. I'm assuming the swash moves in the opposite direction of the airframe when you tilt the heli and do all the ground checks. Otherwise you probably would have crashed right off the deck.

Set it up so you have around 125% servo travel, 60/60/45 or so in collective, 40-50 in the bell and hiller, 75 or so hiller decay, 50 give or take for overall gain and maybe around 15 in the dampening.

If it flys well there then you might have to accept the collective stick feel there. If it doesn't then the geometry must be off in either the swash or blade grip arms. Maybe too long.

I'd give it a try Collin, if it doesn't work then you can rule that out.
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 01-06-2013, 03:05 AM   #34
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

Thanks.

I am not using gel for mounting any of my 720s, so that is not the problem. My vibes are fairly low - mostly below 1 as an overall vibe in the playback logs.

The numbers you mention are almost what I am currently running, except the collective swash mix;

Bank 2 (what I normally fly) - 60/60/30, Cyclic gain = 40, Bell gains = 30, Hiller gains = 50, Damping gain = 15&15, Tail gain = 40, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110

Bank 1 (after reseting to scale defaults and reducing control rates) - 60/60/30, Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 45, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120

Bank 1 is worse than Bank 2.

The heli flies OK (not brilliantly, but acceptable) in calm conditions, which indicates that the geometry etc is OK. It loses the plot if there is any wind, so there is something in the way the SK720 reacts to the wind

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 01-06-2013, 08:01 AM   #35
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

My 700e will somewhat scoot to the left from tail rotor thrust but it is sitting perfectly level in a hover. And the increments in the trim are pretty much to large to dial it out completely without going back to the right. Wind will make it drift, there is a lot of surface area on the scale fuselage and it's a 550? Smaller anyway.

One other thing occurred to me, at what point are your servos 90 degs? Remember you get the most throw and the fastest throw at 90 degs and from there it tapers off. So if the servo is centered at say +8, then that will be where the fastest movement is. May be back to mechanical gain for the SK, not sure on that one.

I would still try to set it up like "normal" and dial out the last 6-7 degs at the bottom of collective with the curve. I think the SK really needs the numbers to be pretty close in throws to handle the way I think you want it to. That's about all I can come up with.

And maybe post a few pics, might see something.
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 01-07-2013, 02:56 AM   #36
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

Thanks.

It is a 500, but it certainly does have more area than a pod and boom, but a lot less than my 700 sized Long Ranger.

My servos are at 90° when I am getting about 4° of pitch, and it hovers at about 5-6°, so it is pretty close to 90° at hover. I have the servo deadband set at 5 currently, and have tried it at 3 as well.

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 01-07-2013, 07:17 AM   #37
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

5 for the dead band seems kind of high to me, that may be contributing to the mushy feeling with some settings. Try to stick to the basic numbers and work the mechanical aspect.

Ah, finally dawned on me. I think you really need to go to 0 degs mid stick. Remember in the setup wizards the everything is set to mid stick, 0 degs. From there you measure and adjust for 10 degs for ail and elev. Since you are at mid stick with 4 degs collective you already have added 4 degs of ail / elev to the overall blade movement. So that will give you 14 degs of ail / elev movement and thus make it feel twitchy and or react much faster than normal. You could verify this by measuring the blade angle at mid stick and holding full cyclic. Or use the wizard to hold mid stick and what it thinks is zero blade angle and full aileron. Or is it elevator. Anyway hope you get the idea. The Skookum just doesn't like it.

You also might be able to pull a Jedi mind trick and move the collective to zero pitch, leave the cyclic centered and reset stick scaling there but now you are in dangerous territory. I don't think I would do it without some serious measuring and careful testing.

From the manual...........
Checking Pitch and Phasing
If your SK 720 equipped heli seems like it’s not handling properly, it’s important to check the mechanical condition of your heli as
well as the SK 720. Issues with blade pitch, phasing, and tracking can often lead to handling issues but often are relatively easy to fix.
There are a few factors to consider when checking and tuning your blade pitch and phasing:
• Whether your blades are centred at 0 collective pitch
• Your minimum and maximum collective pitch
• Your cyclic pitch
• Proper blade phasing
• Blade tracking
Setting Collective Pitch
To check if your blades are centred, set your collective stick to 0% and mechanically adjust each blade using a pitch gauge until it
reads 0°.

Good luck Colin.
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 01-10-2013, 02:51 PM   #38
Helos4me
Registered Users
 
Posts: 817
 

Join Date: May 2008
Location: San Diego, CA
Default

Well how's the testing going?
__________________
700e DFC / KDE 700XF-495 and mount
CC Ice2 HV120 / BEC Pro
Sk 720 Flybarless / Batt Bus
Helos4me is offline        Reply With Quote
Old 01-11-2013, 03:24 AM   #39
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

I haven't had a chance to do anything since last weekend (back at work). I hope to get a chance to play this weekend, but it is looking a bit windy.

Will keep you posted.

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Old 01-13-2013, 01:31 AM   #40
Andy01
Registered Users
 
Posts: 3,850
Thread Starter Thread Starter
 

Join Date: Apr 2008
Location: Brisbane, Australia
Default

OK.

I completely re-did the setup in the same way a 3D would be set up.

Pitch = 0° at mid stick, -12.2° at low stick and +12.4° at high stick.
Collective swash mix = 45
Elevator swsh mix = 60
Aileron swash mix = 60
Elevator servo deadband = 2
Aileron servo deadband = 2

Cyclic pitch = -10.7° to +10.5°

I then used the Tx pitch curve to limit my -ve pitch to -3°

I initially left the cyclic bank 1 & 2 settings as they were during my last flight. Bank 1 was still at the Skookum scale default settings except I had reduced the control rates to 120°/second, instead of 240°/second.

Today was not too windy. At times it was almost completely calm to around 5mph, but there was gusts at times of up to 12-15mph, so not too bad.

The "new" feel is different, although I am struggling to say which is better because neither is great.

Previously with the heli set up "my way" there was quite a lot of shimmying/wobbling/twitching in wind where the fuselage looked like it was doing a little dance under the rotor disc for a couple of seconds, but not often big moves.

Now, with the heli set up this way, the twitching seems to be a bit less (not gone completely), but there seems to be some rather significant (enough to make me $hit myself the first time it happened ) moves when it feels a change in wind. It was almost as if it had not responded to changes for a few seconds and then decided to give a big input instead of several small ones. This was happening quite frequently on a couple of the flights when gusts hit.

Here is some notes with exact cyclic bank settings for the 4 flights today.

13/01/13

Re-did the head setup with shorter links to get 0 degrees at mid stick and -12.2 at low stick and +12.4 at high stick. Used the Tx pitch curve to reduce the –ve pitch to -3 degrees.
Flight 1 – light winds with a few gusts. Flew large figure 8s. Tail gains reduced
On Cyclic 2 - Cyclic gain = 40, Bell gains = 30, Hiller gains = 50, Damping gain = 15&15, Tail gain = 45, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – changed scale default control rates only (and this reduced the Bell gains itself). Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 45, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120
Tail felt better with no uncommanded tail movements, but a bit of twitchiness when wind hit. The cyclic on cyclic 1 was still twitchy, on cyclic 2 it felt a bit better, but still not completely stable in the wind. I think it may have been slightly better than the previous pitch setup.

Flight 2 – light winds with a few light gusts. Flew large figure 8s. Tail gains set to 44% on cyclic 2 and 46% on cyclic 1.
On Cyclic 2 - Cyclic gain = 40, Bell gains = 30, Hiller gains = 50, Damping gain = 15&15, Tail gain = 45, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – changed scale default control rates only (and this reduced the Bell gains itself). Cyclic gain = 50, Bell gains = 23&24, Hiller gains = 50, Damping gain = 18&16, Tail gain = 45, Hiller decay = 75, Cyclic accel = 20, control rates = 120 &120
There was some cyclic twitchiness but not much wind so it was not bad.

Flight 3 – light winds with a few gusts. Flew large figure 8s. Changed cyclic 1 from scale defaults to similar to cyclic 2.
On Cyclic 2 - Cyclic gain = 40, Bell gains = 28, Hiller gains = 50, Damping gain = 15&15, Tail gain = 44, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – Cyclic gain = 40, Bell gains = 21, Hiller gains = 50, Damping gain = 15&15, Tail gain = 46, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
Tail felt better reasonable on both cyclic 1&2. The cyclic on cyclic 1 was not badly twitchy, but it did push in some fairly large slow adjustments when a gust hit (which took me by surprise), on cyclic 2 it felt a bit better, with smaller adjustments. I think it may have been slightly less twitchy than the previous setup, but previously there was not such large unexpected adjustments.

Flight 4 – light winds with a few stronger gusts. Flew large figure 8s.
On Cyclic 2 - Cyclic gain = 40, Bell gains = 28, Hiller gains = 50, Damping gain = 15&15, Tail gain = 44, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
On Cyclic 1 – Cyclic gain = 40, Bell gains = 21, Hiller gains = 50, Damping gain = 15&15, Tail gain = 46, Hiller decay = 75, Cyclic accel = 8, control rates = 110&110
The cyclic on cyclic 1 did push in some fairly large slow adjustments when a gust hit (which took me a little by surprise again), on cyclic 2 it felt a bit better, with smaller adjustments.


So it is now set up as close to a standard 3D setup on Normal curve (with -ve pitch limited), and still not flying like my other two SK720 equipped scale helis.

I will keep fiddling with various settings in the hope that I eventually get something that feels smooth and stable. Done 83 flights to date and still not right

Any further advice is most welcome

Cheers
Colin
__________________
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)
Andy01 is offline        Reply With Quote
Reply




Unregistered
Go Back   HeliFreak > R/C Electronics Support > Skookum Robotics


Skookum Robotics Skookum Robotics SK-360 SK-540 & SK-720 Digital Flybar

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Copyright © 2004-2011 - William James - Helifreak.com