3w-24 on 73" QQ yak

[yoyosmuggler]

Has anyone mounted this motor on the QQ 73" yak? I have a pitts style muffler and it looks to me like if the motor is mounted on the thrust line the muffler will interfere with the firewall. I think its important to mount the motor on the thrust line to make sure the thing flys like its designed too. I plan on cutting the bottom of the firewall back to allow clearance but this is a pretty major mod and I dont want to compromise the integrity of the airframe if I dont have too. Just wondering what if anyone has already tackled this probem before I hack away.

The Yo

[randy racer]

i haven't finished mine yet but want to use the 3W 28. keep use posted on weight and performance please. do you know yet what the weight will be?

randy racer

[yoyosmuggler]

I got the motor temporarily set in place last night and it looks like there will be just enough clearance for the muffler. I'll have to use a dremel and trim some of the firewall but not nearly as bad as it looked in the begining. I'll post some pics of what I have so far maybe tonight or tomorrow. As far as weight goes I'm not sure what the final total will be but if it comes in around 11-12 lbs the 3w-24 will have enough power to hover it. The 28 will have a little more power I'm sure, I'm not to worried about being under powered. I had the 24 in an extra fun at probably the same weight range as the yak and it had enough power to do anything you wanted to do. I'll keep you posted on progress.

The Yo

[yoyosmuggler]

Here are some pics of the motor mounting. I still had to hack at the firewall to get the muffler to fit.

[randy racer]

looks like it will work. keep me posted on your progress.

i was not worried about power with the 28cc, but i have read that some were coming in at 12.5 lbs with glow engines. i feel this plane needs to come in at or under 12.5 to have light enough wing loading to fly as it should.

the 72" with a 160 OS came in under 11lbs and flys great. i just hate glow mess all over a nice airplane.

randy racer

[yoyosmuggler]

Well the yak is finally done and waiting for maiden flight. For what is worth this is my opinion of the build. First of all this airframe is not set up for a gas motor so if your putting gas in be prepared for some modifications. The firewall has to be trimmed to allow room for the muffler and a spacer plate needs to be fabed or purchased to get the motor spaced out, I aslo had to fab another mounting for the switch for the ignition. The side of the fuse is foam with thin sheeting which doesn't allow for mounting a switch for ignition. I ended up thowing away most of the included hardware, the servo adaptors went in the trash, the push rods for elevator went same place. I had some long servo arms laying around and made new push rods for elevator from carbon fiber. The throtle control also went in the trash and I made another from carbon fiber. The hinge installation is a hit and miss thing since the slots are covered and hard to find. The wing mounting could be more user friendly also, I had to enlarge the holes in the rods to get the pins to fit. Installing the pins is cumbersome at best, you will need needle nose plyers to get the ones in front installed. I did like the way they instruct you to install the receiver tho, pretty slick using foam and CA to isolate from vibration. I am not bashing the airplane here, just my honest opinion. If you dont have any experience in building you may be scratching your head trying to figure out how things should be done. But I am very happy with the final result. Everything is mounted up and it all came out very clean. The final test will come after a few flights. I think this bird will fly extremely well.

[cloudshaker]

Do you know the All up weight with your setup?

[SkyDemon]

What size prop are you using? It doesn't look like you will have much clearance. I'll be flying off a grass field, and don't want to cut more grass than I need to.

[yoyosmuggler]

Dont have an all up weight yet, will get that maybe tonight and post. The prop is an 18-8 zinger pro. It doesnt have a whole lot of clearance but the grass in the pic is probably higher than the average grass on a runway. I fly off of a grass runway also and after the maiden, which may be tonight if the wind ever dies down, I'll let you know how much weed wackin I do.

[yoyosmuggler]

The wind gods were not with me tonight so no maiden flight report. I did get an AUW of 12lbs. 1 oz.. I have 2 jr8101's on elevator, 2 4721 on ail, one 8411 on rud, one std on tho. 4 cell 1100 mah nicad on ingititon, fromeco 2400 mah li-ion on receiver with regulator. I think that will work just fine.

[SkyDemon]

Better to wait for the "winds to be with you"

[yoyosmuggler]

The wind gods were kind tonight so maiden flight for the yak. The motor wasn't running 100% perfect but it seemed to pull the yak around pretty good. With a little tuning the power will be ok. I took off... added a lot of up trim and it was flying pretty good until the left aileron fell off in mid flight . I managed to get it back on the ground in one piece. After inspection the right aileron was moments away from departing the airplane also. The covering was coming loose in several spots also, but minor compared to ailerons falling off. Guess its back to the basement for some re-attachment of vital body parts. This time I am going to pin every hinge on the plane and use gorrilla glue instead of epoxy. First time I have ever had that happen on any plane I have built.