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RE: JR Helicopter Forum - 8/10/2004 1:36:20 AM   
bearcatf8


 

Posts: 76
Joined: 2/28/2002
From: Clanton, AL, USA
Status: offline 		OK Larry are you saying that the tail twiches in hover Im useing a CSM HGL 200 Gyro I knotice atwitch in the tail in hover not a violent swing. Darrell Mims

< Message edited by bearcatf8 -- 8/10/2004 3:23:28 AM >

(in reply to manion_30)
       Post #: 51

RE: JR Helicopter Forum - 8/10/2004 9:26:47 PM   
manion_30



Posts: 78
Joined: 6/6/2004
From: Macon, GA, USA
Status: offline 		Hi Darrell,
I don't know about the CSM 200, but a little hunting is normal (they say). Mine was so violent it pulled the tail boom out of my hand and I have a good grip. The hobby store that sold me the combo said it would work for a 30 size. JR810 's speed is .1 s@60 deg and the gy401 's speed is .08 s@ 60 degs and DS function was off. It was good until I added trim, switch from normal to HH, HH to normal, or changed the trim then, I guess it could not keep up, even with neg sensitivity numbers. I just installed the 9253 with no other changes (except sensitivity back to 80, 60 in the radio and DS mode) and I had great control.

Some body else my not see this problem like mine, I just posted the info out so who reads it may avoid the same situation. For an extra $35 go futuba

On yours if you don't like the hunting you should be able to decrease sensitivity enough on eather the gyro or radio. I have read the gyro sould be hi say 90 to 100% and only change the radio. I am not sure I guess what ever works the best.

Larry

(in reply to bearcatf8)
       Post #: 52

RE: JR Helicopter Forum - 8/16/2004 6:41:37 PM   
bearcatf8


 

Posts: 76
Joined: 2/28/2002
From: Clanton, AL, USA
Status: offline 		Thanks Larry I'll give it a try!

(in reply to manion_30)
       Post #: 53

RE: JR Helicopter Forum - 8/24/2004 12:21:11 PM   
CromptonS



Posts: 69
Joined: 8/6/2004
From: Newcastle Kwazulu Natal, SOUTH AFRICA
Status: offline 		Hi all,

I have been at this for just one month and have learnt a wealth of information but lack the experience now. I have a Venture 60 with the JR PCM9X and the OS70SZH. There are no locals that fly heli's so I am on my own. I have managed to hover and do slow forward flight. The venture has been flying extremely smooth until recently, and has picked up a tail wag that is quite bad. I have checked the gyro setting etc ( JR G490T and the NES 810G servo ) and all is fine there. I have basically narrowed it down to the engine that is not running too smooth. I have adjusted it slightly and it is running better, but just do not have the knowledge to do it properly. How does one tune an engine? I have the High speed needle about 1 3/4 turns and the medium speed needle one turn out. The idle mixture is about 3 degree's on the rich side. Any help would be appreciated and where else to look should it not be the engine.

Regards
Shane

(in reply to Jan_the_man)
       Post #: 54

RE: JR Helicopter Forum - 8/24/2004 10:49:34 PM   
manion_30



Posts: 78
Joined: 6/6/2004
From: Macon, GA, USA
Status: offline 		Hello shane,

Teaching yourself, that is inspiration, so am I. Has the engine ran lean for any length of time? I would check the easy thing first; like changing the glow plug OS#8. If the engine runs hot the plugs get damaged very fast. Next, I would check the fuel pressure system lines all fittings and muffler for tightness. Any changes in pressure will case changes in engine rpm more on the middle to high side of throttle. Then check fuel lines on the feed side of the tank for pin holes, clogged filter, and header tank if used.

Now for the harder items, you may need to remove the carb and remove the filler adapter and needle valves to check for any unwanted materials. My OS32 had a piece of (looked like balsa) in that chamber area. I have no idea how it got there, but it created a non constant fuel flow and needing to readjust constantly. Next check carb and back plate screws for tightness.

You may need to recheck the engine alignment to the clutch or the clutch may be slipping at hover, which would cause torque problems. You never mentioned any crashes, If the rotor stops and the engine is till an 1/2 or 3/4 throttle the clutch will wear down fast. Last you may have some bearing damage starting. If you have the engine out for any reason I would lube the bearing in the clutch assy (white Lithiem) very small amount. next check bearing and shaft end play on the starter shaft assy. These items run at engine speed so they wear faster, they also need to be lubed if not a sealed bearing.

Tale rotor bearing, loose belt, and gear meshing can cause similar problems of loading the engine down instead of bad running engine

Throttle setting, I would go with the OS instructions for the engine. I anchor my heli and adjust High first and tach max rotor RPMs and reduce to the rich side 300 rpm. then set idel for transition to mid throttle, then the mid setting for the transition to high RPM and back to high setting for any changes. Repeat one or two times until no further adjustment are required.

Then you will need to recheck your pitch/throttle curves for desired rotor RPMs. Your rotor system is probably worn in now and may have more pitch causing a load on the engine.

These are only a few thing that come to mind and give you something to think about. Ha ha

Happy tinkering

Larry

(in reply to CromptonS)
       Post #: 55

RE: JR Helicopter Forum - 8/25/2004 7:08:09 AM   
CromptonS



Posts: 69
Joined: 8/6/2004
From: Newcastle Kwazulu Natal, SOUTH AFRICA
Status: offline 		Hello Larry,

Thank you for your reply. I will check all those items tonight, I have changed the glow plug OS#8 and opened the carb to check for debris. I do not think that the engine has run too lean ( although I really have no clue ), it smokes a fair amount and the chopper is always dirty with oil residue after flying. I haven't crashed yet, thankfully, and yes I know my turn is coming. I stripped the main shaft yesterday to look for slop etc and found that there is wear on the shaft at the lower bearing. I am a little surprised because I have only used about 7 tanks of fuel through this chopper, it is still new ( Hopefully that is just from my bad assembling rather than normal wear ). I will strip out the engine tonight and check all the bearing and clutch assembly. I did not think to check those items, and it does make sense to me that they can cause torque problems. What you say about the clutch slipping could be a cause, I am not sure but there has been a fair amount of oil residue on the chopper after flying, and I would imagine if this oil get into the clutch area it can cause slip. The tail I have thoroughly checked and am happy that all is well there including the belt. Larry thanks for all the tips, I have lots to check and have more inspiration now. Will let you know how it goes.

PS The throttle curves etc is another whole issue which I am only beginning to understand now, I have the settings where the chopper flew stable written down. I will use those until I fully understand it. I would love to know how the swash mixing actually affects the chopper. Mine is +60 +60 -85 at the moment, I don't know if it is right but it flies and quite stable ( except for the wag now )

This Internet is a wonderful university

Thanks
Regards Shane

(in reply to manion_30)
       Post #: 56

RE: JR Helicopter Forum - 8/25/2004 9:35:38 PM   
CromptonS



Posts: 69
Joined: 8/6/2004
From: Newcastle Kwazulu Natal, SOUTH AFRICA
Status: offline 		Hi Larry,

Done much to the chopper tonight. If the wag is gone I will not know what it actually was. I will fly it tomorrow afternoion weather permitting. 1 Cleaned the Carb again, 2 Replaced all the fuel lines, the one line was a bit brittle where it goes on to the muffler, 3 replaced main shaft and bearings, it was almost as if the shaft was turning inside the bearings, although the bearings moved smoothly, 4 checked and cleaned clutch assembly, it was quite dirty and oily, the bearings are sealed and move smoothly, 5 Checked Starter assembly, also moving smoothly and sealed bearings. 6 Cleaned all the gears. 7 Replaced tail rotor blades with carbon and rebalanced. 8 Installed a muffler gasket as i did not have one and it was leaking a bit. Will let you know what happens

Regards Shane

(in reply to manion_30)
       Post #: 57

RE: JR Helicopter Forum - 8/26/2004 12:10:33 AM   
manion_30



Posts: 78
Joined: 6/6/2004
From: Macon, GA, USA
Status: offline 		Hi shane,

I had Larry heli setup 101 almost a full page on CCPM, pitch/throttle curves instructions engine vs pitch vs tail rotor, all of it and RCU program dumpped it. So I will do a quick version.

CCPM setting: the +60s are the amount of movement in degrees that elev and ailer can move separately. the -85 is th pitch change for all three servos together this would be max pitch, the neg is another way some radios program reverse the direction of travel and still mix together. It look like you are running to much positive pitch unless you compensated with the pitch curve #5 to adjust to +12 deg or so. My venture 30 is set very close to your setting and they are not right, but the only way to adjust the -2 deg at idle. To much pitch the engine will not maintain the power at or close to full throttle or the RPM will drop creating lots of heat.

I strap my heli to a table leaving enough room (1 in.) to see the response as i make adjustments, set engine speeds to max power. However, the purpose is to maintain rotor RPM for any pitch change - 0 and + Training 1600-1800 and advanced 1800-2000 RPM. If you are still training I would pick 1800, set you pitch curve for the max, min and hover (hover ether +5 or 0 deg) as per the book and try to adjust you throttle curve to that RPM. I use a tack in foam rubber in front while running and set the radio setting to maintain Rpm from just before hover adjust throttle curve #3 and keep advancing the throttle through #4 and max power #5 for the same Rpm. Then go back to the engine setting for proper max power minus 200 to 300 Rpm rotor speed for rich setting. Now, the rotor rpm is constant and engine rpm is constant the tail rotor has little choice, it remain constant except for increased pitch in the tail. you now trim out the tail rotor in normal mode and then in HH mode, now back to rotor rpm engine settings if changed. Now, the only thing effecting the tail is you telling it where to go, which, changes rotor/engine rpm, but properly trimmed the tail will be more stable, less corrections, easer for the gyro/tail servo. When you advance to flight mode 1 and 2, you will need to adjust pitch/throttle curve #1, #2, #3 for the negative pitch for the same rpm. You can now adjust you tracking easier, set trim for ail/elev, refuel and fly. you should not need any other adjustment except for final trim for hover.

These are critical for proper tail control, advancing to forward fly, and the best stability overall. This is a condensed version and might be a little easer to understand the big picture (constant rotor RPM).

I have a link that shows more than I can explain. http://www.moretraction.com/new_page_3.htm

Larry

(in reply to CromptonS)
       Post #: 58

RE: JR Helicopter Forum - 8/26/2004 8:48:00 PM   
CromptonS



Posts: 69
Joined: 8/6/2004
From: Newcastle Kwazulu Natal, SOUTH AFRICA
Status: offline 		Hi Larry,

Well Im back again with little success. After all that work the problem is still around. Not all negative though, Ive at least narrowed it down to a tuning problem, of this I am pretty sure. I decided to connect my laptop up to the chopper ( who would have ever thought of that ). We have a piece of software at work that we measure sound and frequencies with and display in graph form. I connected a lapel microphone with a long lead to the heli and then fired her up and hovered it. There is a definate spike on the trend when the tail kicks out, so I am pretty sure the problem lies there. I played with the carb quite a bit and she runs smooth and kicks out every 10 seconds or so. Sometimes its a little violent but the gyro recovers her before the 90 degree mark. The guy from the hobby shop tells me that the 70sz-h motor does this while running in and will come right, I not so sure about that, but am hopefull never the less. I will need to build that workbench and tie the heli down and then tune it.

Thanks a mil for all the help Larry, I have learnt much and thanks a lot for that link of videos. So much to learn but I guess that is what makes me enjoy it so much. The chopper is fly-able so I will continue to try and tune but my next move will be to start playing with the curves now.

Many Thanks

Regards Shane

(in reply to manion_30)
       Post #: 59

RE: JR Helicopter Forum - 8/27/2004 2:32:43 AM   
manion_30



Posts: 78
Joined: 6/6/2004
From: Macon, GA, USA
Status: offline 		Hi shane, glade I could help. I have not heard of an engine doing that unless it is hot. (Pre-ignition) poping or crackleing sounds. Yes, I would chech out the pitch curves.

Good Luck

Larry

(in reply to CromptonS)
       Post #: 60

RE: JR Helicopter Forum - 8/27/2004 1:02:47 PM   
CromptonS



Posts: 69
Joined: 8/6/2004
From: Newcastle Kwazulu Natal, SOUTH AFRICA
Status: offline 		Hi Larry,

You seem to have a wealth of knowledge on RC Heli's. Have you been flying them long? What Heli or Heli's do you fly? I ask because I wonder how long it takes one to grasp this hobby completely. It is very very interesting, but frustrating at the same time, not knowing enough. I was thinking about doing some upgrades, particulary my servos. I have the JR 539's on all except the tail at the moment. I had the throttle one fail after only three flights. I was thinking of using the JR8401 servo's but the guy at the hobbie shop reckons I should rather use the JR8301 or the JR 8321. He does not really offer any scientific reason except that from his experience they last better. What about aluminium swash plate? I was thinking of maybe upgrading that to for some extra stability. I know it is probably not neccesary but I was thinking while Im ahead I should do it. If you could maybe tell me too, what the difference between scale and noemal helis are. It seems it is just the fuselage that is fitted to normal heli's. Sorry leaching information out of you, but I have this need for information on the subject. Do appreciate it.

Regards Shane

(in reply to manion_30)
       Post #: 61

RE: JR Helicopter Forum - 8/27/2004 3:22:04 PM   
JOHN5BLUE


 

Posts: 8
Joined: 1/31/2004
From: Hooksett, NH, USA
Status: offline 		hey thanks for the info

(in reply to manion_30)
       Post #: 62

RE: JR Helicopter Forum - 8/27/2004 5:18:39 PM   
CromptonS



Posts: 69
Joined: 8/6/2004
From: Newcastle Kwazulu Natal, SOUTH AFRICA
Status: offline 		Hi Larry,

Me again. I had quite a bit of success this afternoon. I decided to do the thing that one should always do and that is have patience. I adjusted the carb needles only 2 clicks at a time ( instead of the rough 1/4 turns at a time ), and it took time but I have the Heli flying now without any tail wag. I adjusted the main needle first and got it going fairly ok and then the medium speed needle. It still has a little splutter at about half stick just until it gets up to speed then she flies fine. But it seems if I touch either one of the needles now even 2 clicks the wag satrts coming back. I did not count the turns of the needle so I do not know how far out they are. The engine also seems to be running much cooler. I can put my finger comfortably under the base ( the hollow piece directly under the drive shaft ) of the motor ofter flying as tank out, and there is a much more constant flow of smoke out the exuat now. I tried the Linier curves today 0 - 50 - 100 but found it a little sensitive for me now. I am using 0 - 60 - 100 on the throttle and 48.5 - 69.5 - 100 on the pitch. I seem to feel quite comfortable with these settings. they are probably totally wrong. My total pitch is set mechanically - 9 to 9 degrees.

I am feeling much better today, thanks once again

Regards Shane

(in reply to manion_30)