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Home✈️Aircraft🚁HelicopterCentury Radikal G20-30 N640 Hawk Predator › For me, A new Trouble shooting option.
03-30-2010 10:36 PM  10 years ago
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Frank Bostwick

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Cincinnati Ohio

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For me, A new Trouble shooting option.
I have been burnin the nitro on my Raven and NX. I have also been chasing a vibration problem on the Raven that was introduced, I think, after the lightest of tip overs during an auto. Didnt bent the F/B or even strip the tail gears. You guys gotta know that was a light tip over.
Anyway, I bring it up and all smooth as silk. no bubbles, tail fin is a rock, blades tracking with laser precision, flip into I1 and nothing changes. I fly away. Fly for 3-4 mins bring it back tail in and the tail fin is blurry, as it settles in to a hover the vibration intensifies. Now the boom supports and boom are visibly shaking. T Hold and auto in. Norm mode scroll back up, smooth as silk. Lift off, go to I1. Sounds lean, blades mis track, vibrations intensify, boom and sisters dance.
Thought it was TT bearing outta the holder, checked it. thought it was the feathering shaft, changed it or the dampers (red) changed em. Thought it was the blades, put the Radix on. On the "light" tip over I pulled and checked the main shaft, GTG. Also pulled the motor back plate and head as I replaced the bearings this winter. Looked perfect. New clutch and liner. All bearings cleaned (ultrasonic), bearing buddy packed, and hand checked for smooth rotation (all done during winter tear down). Im thinking I have some, when its warmed up lean issue (btw all fuel lines new).

So Oh yea the "new thing" Sold the motor outta the Hawk 50 and I have a complete upper half air frame hanging on a hook. Im gonna put it on the lower frame tomorrow (it'll take less than 20 mins) and go fly.
To me, thats pretty cool and Ill know if its the motor

AND I Always appreciate your input on trouble shooting.
RIP ROMAN
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03-31-2010 12:32 AM  10 years ago
hbk2owner

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indianapolis, Indiana

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Did you check the ball links?Had a trex 250,kept chasing vibrations, changed the main,featering shaft and fly bar.It was the ball link on the grip...I know its a different bird but it has a blade strike that didnt seam that bad...
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03-31-2010 01:09 AM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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good idea Ill check emRIP ROMAN
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03-31-2010 01:51 AM  10 years ago
James Kovach

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canton, oh - US

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How about the spindle? Did you check that?

Is it the Alum/Plastic Rotor Hub? It could be cracked or twisting a bit.
*disclaimer: These are my opinions. Agree or disagree, Your Call :)
Let'r Rip Tator Chip
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03-31-2010 11:46 AM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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AKA feathering shaft?, its new and straight.
Really looking for some help on this one guys and thinking its a lean over speed thing but if I knew I would not be typing.
no gov. running curves
RIP ROMAN
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03-31-2010 01:32 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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Small update. 13 flights since winter rebuild, 15% nitro (one brass head washer as stock), Did not exhibit issues in first few flights, Same glow plug (OS8). Just pulled back plate and head-totally spotless, clean and bright, no detectable metal/foreign particulate, glow plug looks new. All bolts were tight before removal. Really kinda thought I find a loose bolt/air leak but didnt. Muffler is tight.
Full metal head on this heli. Starting to run out of places to look.
BTW gonna skip, for today, the upper mechanical switch but I still like the idea of it.
RIP ROMAN
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03-31-2010 04:38 PM  10 years ago
oldfart

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Vancouver, Canada

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How much flight time on the heli?

1 - check the tail rotor hub. One of the spindles might be bent a bit.

2 - check the primary shaft and its' support bearings. If the shaft is worn at the bearing area or one of the bearings is notchy it will cause such a vibration.

3 - Check the bearings that support the front tail output shaft. If one of these is notchy, it will binding at higher rotor speeds and you can get a high frequncy vibe

4 - ditto for the tail rotor output shaft
Phil
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03-31-2010 04:52 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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Thanks O/F. Just did a flight and I thought it was worked out. Changed my motor tune and did the whole flight hard and fast, stoppin by the F/L to check. It was all smooth as can be. Then w/ 1/4" of fuel left, I brought it by, settled in and the vibe came back. Dang it soo close.
Counter shaft is new as is tail out shaft. Tail trans out is used but checked good on build, trans in........Must be used as I dont have a note on it...could be. Tail hub is possible those can bend just a bit and its hard to detect. Gonna try again at 1pm, if its still evident, it'll be tear down time...........schist.
RIP ROMAN
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03-31-2010 05:04 PM  10 years ago
steve9534

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yakima, wa.

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Motor tuning
If you think it's caused by running lean, why not richen it up a little and try it? You'll know in 5 minutes whether or not that is the problem. steve.
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03-31-2010 05:45 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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IM with you. That was the focus of the last flight. I though I had it whipped till the last 1-2 mins of flight. I had riched up my mix screw and started at 1.5 turns out on the needle. Stopped 3x during flight to get the needle/temp dialed in and it was just about right (5-6sec touch on the back plate) Riching the mix did help my top end and scroll up and like I said, no vibes long past the point in the flight they had showed up prior to..
I gotta say though I find it hard to think this amount of vibration is motor tuning. Im tellin ya, the boom and supports are going nuts! Soon as I hit Thold and touch down it all goes away instantly. Scroll back up and until you get to higher rps its smooth as Ive ever seen it. But the first 8-9 mins of flight were great no matter the load.

You might have guessed, motor tuning is not a strong suit of mine,
YET
RIP ROMAN
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03-31-2010 06:35 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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Probable cause:
You know its always the stuff you just changed..........
Went to a fuel magnet and Haynes line this year.
line came off at the bung. Try again at 2:30
RIP ROMAN
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03-31-2010 08:32 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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AARRRGGG!!!Well that was a problem and I corrected it. This time with 2-3 mins of fuel left and a smooth running Raven, the dang Throttle servo craps out, motor went to idle (I guess). Im 50+ feet up, no problem but 40 yards in to the deep woods, with a strong head wind trying to keep me from the field.........Head wind is great for autos but not in this case. I had to trade height for yardage over ground. Thank goodness I made it. It would not have been too bad if the Throttle servo not decided to go to 1/3 or so...........Would not respond to stick commands. I was down one hill and up another 50 yards away. Long and short is one fried clutch, one stripped 9252 gear set, landing skid and a dented boom. Hope the unseen damage is equally light. But that was one frustrating day!!
Now, of course I wonder if the servo was acting up the the whole time...........
RIP ROMAN
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04-01-2010 07:36 AM  10 years ago
Gearhead

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Vt

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Trouble shooting option
heehhe hee

I have come to the conclusion (well the word "experience" may be a better word to use ), that if you crash a given heli some 14 or 15 times, and in those 14 or 15 crashes you buy (as well as parts) some 4 or 5 kits for replacement parts, at that point of 14 or 15 crashes you should have enough Extra Parts to build an Extra Heli,, then after some 4 or 5 more crashes (the 18 or 19 crash point) if you buy 1 or 2 more kits for parts, here too at that 18 or 19 crash point you should have enough parts to build another Extra Heli,,

NOW, I have to add, at that 14th or 15th crash point, when I had enough extra parts to build that extra Heli, and I did build that Extra Heli, well that Extra Heli only lasted some 10 flights, cause I crashed that Extra Heli ,, now I'm at the 18 or 19 point and all I need is Blades, a Boom and 3 Shafts and I can have that Extra Heli again
Jim
Buzz Buzz Buzz
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04-01-2010 12:32 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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Man, that is so true. At this point I have bagged and RTF, complete tail assemblies, complete main shaft on up head assemblies, counter gear, tail out, on and on. It does make the repair process go alot faster when you can pull complete assemblies off the shelf.
But DANG MAN, just when I had the kinks worked outta this build........
Hate it when that happens
RIP ROMAN
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04-02-2010 05:50 AM  10 years ago
Gearhead

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LOL funny you mentioned Rotor Heads, I have enough parts to build 4 complete SE Heads now, but I don't have the Flybars and I may need 2 or 3 Radial Bearings, but I wont build them cause when I get my money back from the Wife (LOL) I want to go with the 7mm Spindle Setup, so I will have to get the Spindle, Bearings and other stuff, I think I need the Radikal Grips too..Jim
Buzz Buzz Buzz
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04-02-2010 01:06 PM  10 years ago
Frank Bostwick

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Cincinnati Ohio

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7mm, thats the swift shaft, yes? Whats up with using that in a stock and or metal 50 head?RIP ROMAN
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04-02-2010 10:34 PM  10 years ago
Gearhead

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Edited (the 550 Swift has an 8mm Spindle)
yes, the 550 Swift has an 8mm Spindle, the 620 Swift has an 8mm Spindle (just checked), but I was going to use the Spindle and Grips off the Radikal,,

to add I am going back to the Plastic Grips on my 50s, the Metal Grips give a Lighter Feel and I don't care much for that Lighter Feel, I also feel the Plastic Grips make the Heli Track better and I like that, somtimes I like to just set and hover just 2 inches off the grass and hold it there, I find that to be just so cool, you can go up, zip around and doo all that flipping, rolling and other stuff then come down and set it just 2 inches off the grass and set there in one spot, that just shows the variability in this heli..
Jim
Buzz Buzz Buzz
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