kosta
Heliman
Location: Melbourne Australia
| UPDATESHi Paul, ya know what's freaky? I was logging on to runryder tonight to post updates and to my surprise you've done the same.  There must be a connection. 
Since replacing the original belt with the wider Raptor Titan belt I had some problems. The narrow pulley guide started to damage the side of the belt after one tank.  I took the guide off and used four small standard bearings butted up against each other instead. Sure the bearings don't actually guide the belt, but atleast the belt rolls nicely on the bearings and stops the belt from touching the end of the boom. Went to fly another tank with the mods and noticed the tail was vibrating.  I landed and as she spooled down I watched the counter pulley, it looked like the belt was jumping every couple of revolutions. I rotated the blades by hand for a closer inspection of the counter pulley and yep sure enough the belt was jumping on top of the pulley teeth causing the belt to tighten and loosen with every revolution. So that's where my vibration was coming from. I second guessed myself whether I had purchased the correct belt so I pulled the tail off and checked the teeth of the belt with the original again. They were exactly the same so it's not the belt. I took the pulley out to find what was happening. I ran the belt around the pulley in my hand and sure enough the teeth spacing on the pulley were a tiny amount too close together causing the belt to jump. I pulled the pulley apart, yes it is a two piece unit, and broke out the dremel with the little metal ball grinding bit. This bit is a perfect fit for grinding in between the pulley teeth, making the grooves just a little wider. I did this to both pulleys. I put everything back together, set belt tension and crossed my fingers. Rotated the mains by hand and the belt didn't jump once.  Spooled up, lifted into a hover and whadda ya know, silky smoothe.: Now I know why my original belt lost some teeth, was a good feeling getting it sorted even though it was a bit barbaric.  If anyone has the same problem and doesn't want to use the dremel, I've since found out you can use Raptor pulleys and tail output shaft. You gotta be a little creative in Aus since we don't have a local QWW parts supplier.
Next problem. Well not really a problem just a minor oversight on my behalf. With everything running smoothe I was looking forward to some good flights. Lifting off into a hover everything would be nice and vibration free for the first few minutes and then a major tail buzz would develop.  The boom supports and horizontal fin would become a blur, really high frequency vibe and loosens a lot of bolts. What now I thought. First thing to mind was the mods I had done to the pulleys and what not, but upon inspection everything looked fine and why the buzz only after a few minutes and not right on lift off.
Then a light bulb went off, well maybe an led, I remembered reading here on RR about gasser engines causing vibes when running lean. As I was already 1 1/2 turns out on both needles I thought no way, that couldn't be it! So I turned both needles out a couple blade widths, lifted off and hovered, and hovered and hovered, waiting for the dreaded buzz to surface, but it never did. I have since flown five or six tanks and everything is sweet. I even put the canopy on for the first time. I think she started running lean because the temps here in Aus have really dropped (well it is winter Einstein) since I first started running the engine. I have burned about ten litres of fuel so far, another couple and I'll change over to synthetic and see what she can do. The shellite I'm running is working well.
I would like to take a short video (time permitting) of my Dominator in flight to post here, simply because there are no OD gasser vids here at all or anywhere for that matter.
Anyway, sorry for the long post and I hope some of it makes sense to someone. Cheers, kosta.
p.s Paul, do your tail grips have thrust bearings? If not, do what I did and fit a t-rex 600 hub and grips. They have thrust bearings and only 19 bucks from wattsuprc here in Aus. Cheers. |
