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A Main Hobbies . Boca Bearings . Modefo's RC Helicopters

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Century Hawk - Falcon - Raven - Predator > Tail wag/ Head speed
 
 
Jerc 77
Heliman
Location: Honolulu

So, my Raven has had a tail wag issue for quite a while. I have lowered the gain on the JR 500 Gyro (that is going in the trash and a 401 or 611 will take it's place). But the tail has always wagged. Now that the engine (OS 50 SX-H) is getting broken in, the tail is getting worse. I figured out that if I lower the throttle curve the wag goes away. Why is that?
I don't have a heli tach yet, but that is the next tool on the list. Anyhow, when you take the tach reading, where on the rotor do you take it? Wouldn't you get a different reading up close to the head as opposed to out by tips? What should it be turning at?

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-21-2008 11:36 PM
 
 
Pistol_Pete
Elite Veteran
Location: Tampa Bay non-Buccaneer

this may very well be that you need larger tail blades given the head speed being used.

had similar experience when going with larger main blades and increased head speed.

<><>...the lunatic is in my head...<><>
04-21-2008 11:37 PM
HOMEPAGE  
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

Reference to your tail rotor, did you assemble the thrust washers correctly? I ask this because I also had a similar problem with one of my Falcons and after reading a article on Ron Lund's webpage, I rechecked the washer and indeed, the thrust washers were not properly assembled.

Try changing (if you have a spare) the tail rotor and recheck for the wag.

Ray Fernandez - GUAM
04-21-2008 11:47 PM
 
 
Jerc 77
Heliman
Location: Honolulu

Well, when I got it, it was 80% assembled. Though we (my buddy who is a fair heli pilot, but meticulous mechanic) checked every bolt, dogbone and ball, we may have over looked that. So, do I strip the tail all the way down and rebuild it with new thrust washers? Or just check the ones that are on there? I don't mind buying new stuff. I'd rather spend $30 today than $300 tomorrow!

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-22-2008 03:24 AM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

Remove the tailblade holders and check to see if the thrust washers are properly assembled. The larger diameter washer should be closest to the center of the tailrotor hub and the smaller diameter washer should be at the end.

Ray Fernandez - GUAM
04-22-2008 05:30 AM
 
 
Jerc 77
Heliman
Location: Honolulu

Well, I took the tail apart and put it back the right way. I couldn't tell a difference in the thrust washers, so I got out the calipers and sure enough one is smaller than the other. I don't yet know if that was the problem because when I pushed out the bearing assembly, most of it ended up on the rug. I clean them up, lubed them and put them back in properly. We'll see tomorrow if that was the problem. I hope it was.

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-22-2008 07:11 AM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

Quote 
when I pushed out the bearing assembly, most of it ended up on the rug. I clean them up, lubed them and put them back in properly

Are you meaning that the ball bearings fell out (The little round steel balls) and are no longer contained in the race? If so, you will need to replace the ball bearing race.

Ray Fernandez - GUAM
04-22-2008 10:35 AM
 
 
Jerc 77
Heliman
Location: Honolulu

No I put an allen wrench in one end and pushed. The outer bearing, the thrust washers and the bearing race all went flying. I pushed out the parts on the other tail grip so I could get a count of exactly how many little pieces I needed to find. I got them all back. But no, the actual bearings in the race stayed in tact. I don't think I would tackle trying to put those little buggers back inside

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-22-2008 05:20 PM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

Quote 
I don't think I would tackle trying to put those little buggers back inside

I actually know someone who would do that.

Keep us informed as tot he progress.

Ray Fernandez - GUAM
04-22-2008 10:19 PM
 
 
Jerc 77
Heliman
Location: Honolulu

Well, here's an odd twist of events. I redid the tail last night and took the heli out today to check it. Still the same wag. So, I referred back to the binder that I keep the instructions for the heli, the engine, and the gyro in. I read through the gyro instructions for about the 18th time. They said the same thing as the last time I read them. So, at my wits end, I went back over everything. I discovered that at some point the gain lead for the gyro was put into the receiver backwards! I just never saw it during preflights. So, I reversed the lead and fired 'er up again. TADDA. No wag. I still need to mess with the gain some. However, I did learn a bit about dynamic rollover today It leaned hard to starboard. Probably would have kept going if the blade hadn't stopped it. Now I need new blades and I stripped the servos. So, I am now researching new servos for the swash plate. I am a Futaba guy, but this one has the JR DS811s in it. I don't think Futaba makes a comparable servo. Anyhow, I am open to suggestions. What do you guys have for servos? How much torque and fast do I need them to be? Thanks for all your help so far.
On a different note: I know that I can fly. I know how to preflight my helis, I know what needs to be done for maintenance, and I generally buy the best parts I can find. But, the last 3 times I have been out flying, I have had "incidents". 1.) a blade strike on my Trex. 2.) lost the Trex in the sun (totally my fault). And 3.) A blade strike on my Raven. This has been a hell of a week! I was thinking of taking the Trex with me up to Alaska tonight, but I think it's best to leave it at home for a while.

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-23-2008 12:12 AM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

Good to hear you got the problem figured out. Sad to hear that you had a mishap.

On my Ravens, they are all outfitted with Futaba 9252s for the control surfaces. My gyros are the GY601 w/9256s for tail control. These seem to be really good combinations for this heli. I know some people using 9451s but have upped thier power supply to 6 volts.

Ray Fernandez - GUAM
04-23-2008 12:35 AM
 
 
Jerc 77
Heliman
Location: Honolulu

I just had a message from Speedbmp and he said the 9252 servos are only $68 at heli-world! I think that is the answer I was looking for. I also think I am going to get rid of my gyro/servo combo and go with the 401/9254 combo. I am into scale maneuvers. No 3d and I don't really see myself going that way, so is the 401 good or do you recommend the 611? The price difference is $380 (611) and $220 (401). I don't mind spending the cash, I just don't want to if I don't need to? What do you think?

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-23-2008 12:48 AM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

For scale, the GY401 combo is a very good choice. The GY601s and th GY611s can still be used but for the money, you can't go wrong with the 401.

Ray Fernandez - GUAM
04-23-2008 01:33 AM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

BTW, since you are in Hawaii, check with the guys over at the Pali flying area. Some good items being sold by them. You can even get some good stuff from Bob (aerospire).

Ray Fernandez - GUAM
04-23-2008 01:35 AM
 
 
Jerc 77
Heliman
Location: Honolulu

Thanks Ray. I am pretty new to the island, and I travel a lot. I'm not sure where Pali is. I'll find it though. I think I am headed your way in August. I'll be out at Andersen for a few weeks. I'd like to meet and see your helis and your field.

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-23-2008 01:45 AM
 
 
Ray Fernandez
Key Veteran
Location: Guam (U.S.A.)

Come visit when you are on Guam. Most of the flyers meet on Saturdays and Sundays. Some of the harcore flyers go everyday.

The flying field on Oahu is located by the county swamp area. Take the road leading up to the Pali Lookout, go through the tunnel, downhill. Two traffic lights later, turn left towards the landfill, passing the process center and the field will be on your right.

Ray Fernandez - GUAM
04-23-2008 02:10 AM
 
 
Jerc 77
Heliman
Location: Honolulu

Yeah roger that, Kapaa Quarry road. That's where I was today. I usually fly out at the Marine Corps base, but that is only open on Sundays and the seem to frown on helis. So, I fly out there at Kapaa Quarry when I want to fly the heli. I'd like to check out the flight line on Guam. I'll see you this summer.

"Everybody talks about the weather, but nobody does anything about it." - Mark Twain
04-23-2008 03:06 AM
 
 
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Century Hawk - Falcon - Raven - Predator > Tail wag/ Head speed
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