2.1 comp-arf YAK

[billoliam]

Hi Wingburner.
Have you tried Pbg composites in new zealand.Thats were I will get mine from.
He can get them made to that diameter.
I have had all my tubes from him and they have all been perfect.

[reyn3545]

I got home from the Scout campout early enough to get the aileron control horns in before the wife started complaining about us not spending any time together this weekend.

The slots are not wide enough for the supplied horns, so you'll have to drill them deeper and longer with the dremel. The instructions tell you to align the control arm linkage holes even and perpendicular to the edge of the aileron hinge... be careful here, if you do that, the control horn will limit your downward travel of the aileron! They really should have horns on here that reach forward more than the ones supplied.

[Pittsflyboy]

How bout DA, the are handling PBG producs CF.

[reyn3545]

Lots of folks want to swap out the wing tube for CF. The tube in this plane is 30mm thick, which is not much. Even by PBG's estimate, you'll save about 2 ounces over a standard aluminum tube. If the plane weights 17 pounnds, that's less than 1/100 of the plane's weight.

Also, on this plane, the CG is not on the tube, its BEHIND it... so, if you take off weight in front of the CG, you'll have to move or add weight behind the CG to compensate. Also, if you guys are considering building the plane with a Pitts or something other than a canister, chances are you'll be adding weight in front of the CG anyway. A friend of mine built a 100cc CompARF Extra, but he used mufflers instead of cans on it. He wound up shifting batteries and everything possible up front to try and compensate, then he had to add 1/2 a pound inside the cowl to get it balanced!

I built my 100cc plane, used cans, and didn't have to move a thing from its original location.

Moral to this story... if it was designed for cans... use them!

[pepatrick]

Mike...while you were working on little baby Yak...you missed a great flying day...Winds were in check...and lots of good flying...and little bit of crash entertainment at the field...Fortunately none of it mine...A Big 150cc secret Extra bit it today...Theres only one of them..So I am sure you know who it belongs to. Other than that...beautiful day...My Monroe trip got pushed back so I will be up during the week to get some flying in...come up if you can.

[reyn3545]

Oh.. man, that was a beautiful plane! I was on a Scout campout Friday and Saturday night, and I had 5 yards of mulch to spread out when I got home today! I'm lucky that I got 2 horns glued in!

Next week I have a kid's birthday on Saturday, and I'm being reminded that Sunday is Mothers' day, so it looks like it may be a while before I'm in the air again. The Extra and the bipe are ready to go, just waiting on time and calm winds.

I'll be in meetings here in Atlanta on Monday and Tuesday, then in Ft. Lauderdale on Wednesday and Thursday. Maybe Friday will work... its too soon to tell.

So, the crash... what happened?

[pepatrick]

He was flying and doing the crazy stuff he does...really low to the ground...maybe too low..He is absolutely one of the best 3d pilots I have ever seen making the plane dance the way he does..I guess he was just flirting with too low and pretty much landed upside down...I think the plane is repairable...but since it is one of a kind..its going to be tough to get parts. I am sure EF will be able to get parts for it.

[reyn3545]

I hate to hear about that... I'm sure if anybody can get it back in the air, he can... but it still had to be a heartbreaker.

[reyn3545]

I was able to do a little more building today... got the lower cowl and firewall installed, measured for the offset motor mount holes and got the motor test fitted.

I will have one problem... I decided to go with a canister muffler, and the custom pipe that CompARF sends starts to bend as soon as it leaves the mounting flange. That makes it IMPOSSIBLE to get the back bolt through the mounting flange and into the cylinder head.

So, I'll make a trip to the hardware store this week and try to find a stud, lock washer and nut the same size as the bolt. Hopefully there's enough room in the bend area to get a wrench on and tighten the nut!

Other than that, pretty uneventful. The firewall is a little bit of a challenge, trying to get everything perfectly centered, drilled and mounted, but once you decide to just make it fit.... it will!

I used the standard 2 1/2 inch standoffs, and other than washers on one side for thrust angle, I didn't use any additional. The carb air inlet is probably less than 1/4 inch from the firewall, so just to make sure there was plenty of airflow to the carb, I cut a 3/4 inch hole through the center of the firewall right in line with the carb inlet.

[pepatrick]

Mike,

I have had that problem before. I had the flex pipe and it bends back right after the flange. I took a dremel tool to the head of the bold and filed it to an angle. Then I was barely able to get it in the hole. When that pipe broke after about 8 flights...I got a solid pipe that seemed to have much clearance...I was able to use a new bolt and tighten it up. This is on my EF 50cc Yak...what a pain in the arse...but I have had no problems since then.

	Quote: Originally Posted by reyn3545
	I will have one problem... I decided to go with a canister muffler, and the custom pipe that CompARF sends starts to bend as soon as it leaves the mounting flange. That makes it IMPOSSIBLE to get the back bolt through the mounting flange and into the cylinder head.

[kriel]

Hi i cut down an allen key took some time to tighten (strong fingers and patients of a saint)but with some thread lock ive had no probs, flown with it for over 2 hours and nothing come lose.

[Jamieman]

	Quote: Originally Posted by reyn3545
	I will have one problem... I decided to go with a canister muffler, and the custom pipe that CompARF sends starts to bend as soon as it leaves the mounting flange. That makes it IMPOSSIBLE to get the back bolt through the mounting flange and into the cylinder head. So, I'll make a trip to the hardware store this week and try to find a stud, lock washer and nut the same size as the bolt. Hopefully there's enough room in the bend area to get a wrench on and tighten the nut!

I too had the same prob. But like Kriel said, a cut down allen key works a treat.
I shortened the bolt for that hole & used a chainsaw file to elongate the hole a little.

Should work ok.

But i know what your saying.

[hwka]

I was not aware of this ealier thread when I started mine on the CompARF 2.1 Yak 55 SP / DA50
Those contemplating a build may find some of the information I posted useful.
It is under "Giants Fron Down Under" forum.
Tried to link to it but not sure how that works.

[reyn3545]

OK.. 50 cents worth of parts later, I have the motor, header and can mounted!

I couldn't find a stud the right size for the cylinder head, so I bought a bolt and cut the head off of it, and used a nut on top of it to lock it down. It should be fine.

Here's a few pictures of the motor/header/canister installation. The large hole for the canister is the size recommended by CompARF. I originally had it about half that size, but the body of the can was hitting the fiberblass on the fuse, so I had to enlarge it. The bottom of the can sticks down about 1/2 inch lower than the body of the fuse, so I guess it takes that length of hole to get cleanly back inside the fuse. Not what I had hoped for, but it did give me an excuse to polish up the canister!

You can see in one of the pics where I used the stud and nut in place of the header bolt. Also, to get the header mounted to the can, I got a 1 inch hose clamp (automotive style). I was able to access the screw to tighten it through the hole I cut for the canister exhaust... worked very nicely.

[hwka]

Hi Reyn3545
Yak is looking nice.
I noticed from the photo that your carbon gear is a snug fit.
I fly off a grass strip, which is in pretty good condition.
I found that the flex in the carbon gear to be far more than expected and had to allow at least half an inch topside....learnt the hard way, and that's with soft landings.
Suggest you allow a quarter inch front and back.
The Yak is easier to land than most if the C of G is OK....dribble of power, as she slows down pretty quick, then power off a couple of inches off the deck.