Icepoint problem
 

Just finished my Icepoint which has been under construction for the last year or so. I know, I'm a slow builder. Actually, it got bumped off the assembly line for quite a while.

Anyway, finally made the first test run today on the new YS160DZ which is mounted with an MK soft beam mount and a nose ring. Engine started reluctantly but got it running ok. A brute, to say the least. With an APC 17x12 and Cool Power 30%, about 8000 rpm. But it shakes like crazy, not just at idle, but even above 7000 rpm. Transmits a huge amount of energy into the airframe. Yes, the prop's balanced. Am I using the wrong engine mount?

The resulting problem is that the horizontal stab, which is mounted on a 1/2" diameter carbon tube, with incidence adjusters at the front of the stab, is now so loose that the tips can move up and down about 3/8". The rod for the incidence adjusters is also loose. The fuselage is only about 1" thick where the tube goes through, and the fiberglass sleeve in the fuselage just doesn't have enough length to handle the torsional vibration.

Has anyone else encountered this problem? Seems it will occur sooner or later, even with a smoother running engine. I can replace the worn sleeve with a new one, but I expect the problem will return rather quickly. I guess I could install flying wires like a Pitts, but somehow that just doesn't seem appropriate for a pattern plane.

Comments appreciated.

Jack

RE: Icepoint problem
 

I'll leave the mount choice to others,except to say that the various Hyde mounts seem to be the most popular,followed by the generic Ys one, and the ZN one.
Re the stab tube,it's more or less standard practice,if you need to have the stab removable, to coat a loose inner with medium or even thick cyano, LET/MAKE IT SET THOROUGHLY, then when it's just too tight, lightly sand to fit.

RE: Icepoint problem
 

If it's set where your happy with it, permanently glue it together.

RE: Icepoint problem
 

I think the MK mount is not really up to the job, it was developed in the day of the 120 and the 160 is just too much for it. The Hyde mount is the best imho, but if you need a beam mount then try the YS mount, it will be a marked improvement I am sure.

James

RE: Icepoint problem
 

Jack,

First off the YS mount is excellent. I have it in my Astral and my bipe. If you have questions you can see it run next week when I'm in Alb.

Next is Epoxy the stab tube and adjuster pin into the fuse. The stabs will still come off, but the tube will stay in place and it will be much more solid. This works really well and everything will stay tighter.

Troy

RE: Icepoint problem
 

Question, and this is serious.

Which nose ring do you have on that engine? if it's the nose ring that Central sells, how tight was it? Those nose rings can be so tight they fuse to the engine and utterly defeat the mount. In this case you can't even remove it with your bare hands. You have to drive it back off with tools.

IF this is the case (and it has happened to me), then you need to use a dremel sanding drum and carefully loosen that O ring until it's a snug, but slip fit...then install with lithium grease.

because what you are describing is the same thing I discovered last fall, which prompted me to get involved with Merle Hyde and start testing new stuff. great things have come of it so far, but the root of all of the evil was that super tight nose ring. So if that's the one, just check.

And do what Troy said to the stab tubes, I had to redo my stab tube as well after about 8-10 runs. And don't stop there, check EVERYTHING. I also found one of my wing adjusters had come apart and several other things. Graphic evidence of why soft mounting this beast is critical.

-Mike

RE: Icepoint problem
 

Thanks everyone for the response - all good input. Sounds like a new mount may be in order.

Troy, I'll wait 'til I see you next weekend before deciding on the fix(es).

Jack

RE: Icepoint problem
 

Just to complete the story -- changed to the YS Super Mount at Troy's suggestion. What a difference! Still some vibration at the low RPM's but an order of magnitude less than before. That oil filled damper works wonders. Virtually nothong at med and high rpm. Epoxied stab tube and incidence rod in place; problem appears to be solved.

Thanks all for help.

Jack

RE: Icepoint problem
 

MK mount does not require a nose ring, vibration force from the engine acts like a hammer/vibrator hitting the nose ring and transfering to the stab via the fuseluge. Put the nose ring away which is incompatible with your MK mount. Anyway, YS mount is better.

RE: Icepoint problem
 

where are you guys buying the ys mount from?
I have looked at central hobbies and can not find it listed on their site.

Thanks............

RE: Icepoint problem
 

pst,
It is always best to call Central Hobbies. I got a motor mount last Month from them that was not listed on their site. They are always a great help to me when I talk to them.
Greg

RE: Icepoint problem
 

Thanks Greg i will try that.................

RE: Icepoint problem
 

Got mine from Rich Verano at YS Performance.

RE: Icepoint problem
 

thanks,
Thats where i found mine.....................