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12-04-2005 08:37 PM  12 years agoPost 1
RichardV

rrApprentice

UK

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My apologies to everyone for raising this again, but I've tried reading all the posts, but with no real conclusion. (Apologies especially to Dr.Ben and GM1, I tried reading all your posts, but ran out of bandwidth)

On a Fury Tempest with JR equipment (8511s + 3810 radio)
90° arms at 20mm, no subtrim.
ATV mostly at 100% with max 4% extra to correct for top and bottom.
Swash up and down perfect, no mixes and no dancing.
mechanically centered at +1°.

Problem:
Roll with positive pitch gives down elevator,
Roll with negative pitch gives up elevator.
It makes the rolls look very strange and it's nothing something I can mix out unless I had a radio with PIT+AIL>ELE.

Any suggestions would be appreciated.
Cheers
Richard

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12-04-2005 09:51 PM  12 years agoPost 2
steve kra

rrApprentice

palatine illinois

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noticed this setting up my stratus. my fix. make sure none of you atv's are under 100%. if not use more atv 110-120 readjust swash value. swash expo also has to be used. if your radio has it. worked for me.

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12-04-2005 10:24 PM  12 years agoPost 3
airdodger

rrElite Veteran

Johnston USA

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Did you set the fore aft cyclic wheel at the two and a half degree offset? Atv's ail,elevator,and pitch at 100%. CCPM settings of 60%, 120CCPM function, that is out of the instructions. Is this your first X-Cell did you buy it new, did you build the heli, do you have the swash leveling tool, and the servo jig, the instructions? Fill out your profile a bit so we know how much experience you have and what helis you are accustomed to. If those guys can't help you, then you have a real problem. Chris

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12-04-2005 11:12 PM  12 years agoPost 4
Dr.Ben

rrMaster

Richmond, VA, USA

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Would you clarify the part about "rolls w/ postive pitch" and "rolls w/ negative pitch"? Are you referring to what the interaction is when you're in the positive or negative collective range, meaning it goes one way then the other as you go back in forth to maintain altitude in the roll?

Ben Minor

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12-05-2005 12:59 AM  12 years agoPost 5
rada70

rrKey Veteran

Westchester, NY

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I had a simillar problem. When I inspected the heli I found the two wash out pins (anti rotation) were bent a little. I hope that'll help you.

Just do it.

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12-05-2005 04:44 AM  12 years agoPost 6
RichardV

rrApprentice

UK

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steve:
ATV are all between 100 and 104 percent.
will try using more travel.

airdodger:
sorry about the profile, will update it asap.
it's setup as per the instructions (same as your suggestions) with brand new servos.
I'm using the leveling tool and the pitch is perfect top middle and bottom with no dancing.

Dr.Ben: (heli on table)
Pitch at +6 °. AIL left or right and the front of the swash dips down.
Pitch at -6°, AIL left or right and the front of the swash bumps up

Rada70:
This happens before it gets above the swash. The swash is dipping down when high and bumping up when low.

My radio doesn't have swash expo unfortunately, but I'll get hold of one that does. It's one of those theoretical problems with CCPM with one side servo moving into center and getting more travel while the other moves towards its extreme and thereby the lesser travel pulls or pushes the swash towards center.

I would have throught the software could handle it, knowing that 100% ATV has 60° of travel and there's a set ratio of travel loss, irrelevant to the length of servo. It's an old radio, so maybe I have an old version of the software.

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12-05-2005 11:45 AM  12 years agoPost 7
airdodger

rrElite Veteran

Johnston USA

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Just to check, you have the two and a half degree offset on the elevator wheel and the offset is the correct way. You used the servo drill jig that comes with the kit, if not I could measure the distance for you? Why are the atv's different? Chris

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12-05-2005 12:20 PM  12 years agoPost 8
GM1

rrElite Veteran

Tallahassee, Florida US

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Blades

Symmetrical or semisymmetrical blades? I wonder if the JR is set up for 140 eCCPM?
Gordie

On a dog sled team, if you're not the lead dog, the view never changes.

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12-05-2005 01:44 PM  12 years agoPost 9
RichardV

rrApprentice

UK

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Symmetrical blades, but the interaction is visible on the swash. I didn't know you could set the fury up for 140° with the standard parts.

Does the 2 1/2 ° make a difference? The top servo to the rear doesn't move during AIL anyway!
I'll double check, thanks.

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12-05-2005 02:36 PM  12 years agoPost 10
GM1

rrElite Veteran

Tallahassee, Florida US

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140

The Fury cannot be 140 degree eCCPM. My question would be, is the JR radio set in 140 eCCPM mode? I will ponder this more.
Gordie

On a dog sled team, if you're not the lead dog, the view never changes.

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12-06-2005 02:02 AM  12 years agoPost 11
W_Brown

rrNovice

Augusta, GA

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Has this radio been cleared from a previous model?
It's concievable that there is a trim value hidden somewhere in an older setup. (just experienced this myself)

*gravity SUCKS*

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12-06-2005 05:59 AM  12 years agoPost 12
RichardV

rrApprentice

UK

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The radio was definately cleared before . It's an oldish radio (3810 - analog trims) and can't be set up for 140° CCPM.

I put a futaba RX in and set it up on my 9c and it does the same thing.

It stays pretty level during application of AIL and only dips/bumps towards the end. Is this a simple case of too much throw on the cyclic? I'll measure the cyclic pitch tonight and see if I should reduce the cyclic AFR's a bit.

Richard

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12-06-2005 08:02 PM  12 years agoPost 13
airdodger

rrElite Veteran

Johnston USA

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I took the 2 1/2 degree offset out on mine and what you described in your first post is just what happened. Set the rod length to the exact measurement too. I would go through and get rid of the different atv, as they state do not adjust ATV for any trimming or set up changes, I am sure that could lead to interaction too. All I did was follow the instructions to the letter, I also fly JR. Chris

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12-07-2005 06:10 AM  12 years agoPost 14
RichardV

rrApprentice

UK

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Still no resolution on this dip/bump on AIL.
I checked cyclic pitch last night and am getting 6°, which seems normal, if not a little low.

airdodger:
I used the guide to set the 2 1/2°. My ATV's are all within 4% of each other, in order to get the swash level up and down. I'll try no offset and 100% ATV all the way round, but then I have to use two mixes to get the swash to move straight up and down. Thanks for the suggestion, it's worth trying.

Richard

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12-09-2005 08:43 AM  12 years agoPost 15
RichardV

rrApprentice

UK

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Ok, I spent the night with this heli to no avail. Using a spirit level, vernier, etc, the most correct setup I could get was:
100% ATV on all cyclic servos.
60% AIL, 60% ELE, 77% PITCH swash mix.
perfectly level top, mid, bottom.
mechanically centred on +1°.
pitch range -9 +11 degrees.
6° cyclic pitch on AIL/ELE.

I tried upping the ATV's to 120/150 and limiting the AFR, but it didn't make any difference, in fact, the swash operated exactly the same.

End result, is the swash still dips 1.5 mm during roll at 6° and bumps 1.5 mm up during full roll at -6°. Because the rear of the swash doesn't move, this translates into forward and backward elevator.

This is the best I can get it, so now I'm just going to fly it and see what it does. Thanks for the suggestions everyone, I appreciate it.

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12-18-2005 06:20 PM  11 years agoPost 16
Paul Woodcock

rrElite Veteran

Dubai - United Arab Emirates

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Hi Richard

In short, CCPM SUCKS

Why do you think I sold the F#####g thing and bought a non ccpm machine. Hope you can have more success than I did. I believe you got the machine at a realy "good" price.

I could get a perfect roll at mid stick, with all the bell cranks at 90 deg etc.. but as you move away to + or - pitch and then if you roll one of the servos goes to worse geometry (less pushrod movement) and the other to better geometry (more pushrod movement) and causes a bump up or down on the swash.....I think from what you have said above you have already figured this out....as I said to start ccpm sucks.

I agree a pit+ail to eli mix would sort it out. You could also try longer servo arms and reduce the servo ccpm setup and the servos will stay in better geometry, you will loose some servo resolution. I ran with less than 77% pitch on the swash setup. Can't tell you exactly what it was as I have deleated the program in my radio after Dean baught the heli.


Paul

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12-18-2005 07:10 PM  11 years agoPost 17
da_man

rrKey Veteran

Central NC

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In reply to the previous post. CCPM has advantages and disadvantages. CCPM save the helicopter a significant amount of weight and decreases the part count .

The disadvantage of course is the problem with swash interaction. It is not easy to setup. Problems are also hard to solve. CCPM can never be as precise as mechanical mixing. It is just the way it is.

These are reasons why you still see people flying the pro 2k for FAI and the Fury extreme for 3D. Some applications you need the power-to-weight ratio and in others you need precision.

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12-18-2005 08:38 PM  11 years agoPost 18
Obsessive

rrKey Veteran

41.73N 71.41W

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Try setting mechanical center at Zero degrees.

Are all your servos the same brand, and same distance from center of horn to ball?

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12-19-2005 07:51 PM  11 years agoPost 19
korzry

rrApprentice

Fort Collins, CO

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Here's a thought. Are you ball links at 120 degrees apart? I bought my Fury used. The original owner said he didn't like CCPM and could never get it setup right. He had the two from ball links at 90 degrees from the rear ball though, instead of 120 degrees. It flies great for me.

Ryan

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12-21-2005 01:51 PM  11 years agoPost 20
RichardV

rrApprentice

UK

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Hi Paul
Yep, I'm starting to see the shortcomings of CCPM. Somebody mentioned servo exponential to make the travels linear, but I've never heard of it and my radio certainly doesn't have it.

I'd like to try a ail+pitch>ele+pitch mix but I don't know of any radios that do a 2 to 1 mix.

I could try a longer servo arm to minimise the interaction, but I think servo resolution will become an issue. The frustrating thing is, other than you and me, no-one else seems to have this problem or seems to know what we're talking about.

BTW, my neighbor Andrew claims he knows you quite well and used to fly with you a lot before you move to that other aviation company.

Obsessive:
I've tried mechanical setup at 0, +1, +2 to no avail.

korzry:
Links are definately 120°. It does fly great, it's just the rolls aren't perfect and there's no way I know of fixing them.

Cheers
Richard

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