fly4food18

My Feedback: (15)

I purchased the CMP Yak 54 from a guy at the flying field and i Didn't get a Instruction book. I am looking for the CG, control throws, Canopy attachment. Can any one help me? I am only a couple of hours away from flying it. any other tips? I am worried about Engine cooling, Where should i cut some cooling vents?

Thanks
Brian

topper5

My Feedback: (12)

i built this kit for a guy last fall i think the cg is about 4.7",as far as the canopy i built a frame inside of it and atached it with a nose pin and two screws at the back, other wise per the instructions you secure it right to the fus with six screws, and i vented the motor with a nice half circle in the bottom of the cowl........hope this helps

fly4food18

My Feedback: (15)

thanks for the help. I am having trouble ballancing the plane now. I have added 6oz to the nose and i am getting closes. any tips there?

Thanks
Brian

shotgun06

Look at this tread. You should find the answer you are looking for.


http://www.rcuniverse.com/forum/m_6042513/tm.htm

greyfoxx

Brian - I have the CMP Yak 140 as well. I only had to add 2-1/2 oz to the nose and total dry weight was at 13 pounds.

Here's what I did. First, I used a pumped OS 160 and mounted it as far forward as the mounts would allow. This placed the backplate of the spinner about 1-1/8 in from the cowl (notice the location of the prop and spinner backplate in the photo of the full scale plane)

and allowed me to use all of the weight of the engine and the pitts style muffler to compensate for the tail-heavy tendency. I also mounted the battery pack for the receiver and the throttle servo forward of the firewall as well. Part of the 2-1/2 oz weight I added was a 2 oz spinner weight (check your local hobby shop) which gets a smaller amount of weight as far forward as possible. With this,I achieved a balance half-way between the two CG balance groups given by CMP at 140 mm by adding 1/2 ounce of weight to the forward part of the motor mount. I also only had to add 3/8 oz of weight to the left wing to achieve lateral balance. As I said, total all up dry weight is 13 lb, heavier than I would have liked, but about as close to the advertised weight as most builds of this model are unless there is extensive lightening done by removing wood, etc.

I also used a canopy mounting system very similar to that used by topper 5. I have photos of that set up if you are interested.

If nothing else, remember that "Experience is a hard teacher. She always gives the test first and the lesson sometime later!"

Phillip

opjose

I don't think he has the Yak 1.40, the paint scheme he has is for the smaller version.

fastplane

Greyfoxx, I was quite interested in your solution to the Yak 54 being too tail heavy.
How did it fly? Can you provide picture of your plane with prop out so far?
I also have the NP Yak 54 140. I have a Saito 125 in it. Just made maiden flight Sat 7-14. It flew very smooth and stable and we were impressed that it only took a slight down trim to fly straight and level. There were no surprises and landing was smooth and controlled.
Looks really good in the air.
One of my concerns was that the Saito 125 would be low on power for the plane. This seemed to be correct.
I had to add 3.25 lbs lead around the engine mounting block to get it to balance at 138 mm from LE.
The plane came out total weight, no fuel, 13.5 lbs.
My next steps to achieve more power is to lean out the somewhat new engine. Also to move the engine forward some.
I had no thought of going as extreme as you have done. I would have to use quite a thick spacer to put the engine out even 3/4" from the firewall.
I did not have the original engine mount.
If none of this works I am considering to put a gasoline engine in it. Something along a 38 or 40 CC.

fastplane

Greyfoxx, I would like to see the photos of the canopy mounting system you used.

PointMagu

My Feedback: (11)

I trimmed the two tubs out of the cockpit but left the center support in place. Next, I cut 6, 1/4" pieces of ply and drilled for 4-40 blind nuts. Once the blind nuts were inserted, I used thick CA and glued to the inside lip around the canopy cutout. Drilled six holes through both the tinted canopy and the cockpit frame. 6, 4-40 bolts and washers later, VIOLA! This is the same technique used on my old Goldberg Sukhoi 26MX.

I've made quite a few changes getting the YAK flight ready, (again). I got the airframe from a buddy for selling some motorcycle parts for him on eBay. He flew it stock with a Saito 120, declared it a sled and moved on to other airplanes. He had dinged it slightly so I had to purchase a replacement cowling from Nitro, (fast, friendly and CHEAP).

A few things I've done to overcome that heavy, molded fiberglass ass-end:
1) replaced the dual landing gear legs with a surplus Goldberg Sukhoi gear. 14 oz with axels. mounted a 3/8" ply plate inside of the fuse to thread the 1/4-20 nylons into.
2) removed the solid dowel pushrods with 2-56 threaded rods. ran Sullivan carbon fiber-reinforced Ny-rod pushrods for the dual elevator servos.
3) fabricated dual ply servo trays and inserted higher and as far forward on either side of the fuel tank as possible.
4) using GWS standard, high torque servos. at almost 3.5 oz each, mounted ahead of the CG.
5) installed a Saito 150 bolted to a 3/4" ply plate to move as far forward as possible.
6) placed the Hitech 605BBMG rudder servo with wire pull-pulls into the center position on the stock tray.

I have to admit, I've offset some of this by installing a CB Associates tailwheel assembly with a 1/4" mount plate to the rear underside along with a DuBro dual rudder horn. We'll see as things progress.

I'll try to post a few photos next time.

PM

PointMagu

My Feedback: (11)

Here are the photos I mentioned last time:

PM

willrockwell

We just finished the build on this plane and flew it for the first time on Sunday August 5. Here is the maiden flight [link=http://www.youtube.com/watch?v=yFxcaXp5h-o]Yak 54 first flight[/link]
The plane is heavy because it is fibreglass, even in the tail. The bigger the engine you use, the better it will fly. This is a sturdy plane, and should take a pounding. As you will see in the video, we had to abort the first flight and add weight into the cowl. After that it flew beautifully. We are using an OS 160FX. By the way, the CG is on the tube that the wings attach to. We had to make a tailwheel, as the one that came with it was pitifully weak. We cut a large access hatch in the cowl above the glo-plug. I used velcro to re-attach it, but think we will leave it off for flight, as it is in a good spot to vent the motor.

Lou Pfeifer

Hi, was thinking of buying one of these. Like to know how you like it and how does it fly? Also do you think the cowl has enough room to mount a 26-cc gas motor. All the linlage rods shown on your aircraft seems to be real nice I dont think it comes stock with those!!! Thankls look forward to hear your response. Thx Lou Pfeifer

skybolt1

this plane is so much tail heavy i almost isntalled my old old quadra 35 just for the heck of it, with a moki 1.80 i have to chase a lot of weight to the front.

DaleD

canton3D

My Feedback: (191)

I just purchased a NIB CMP Yak 54 and I like the ARF but I'm disappointed in the elevator set up.I can't believe the flex in the wire ends on the push rods plus the carbon fibre rods with set screws.Has anybody had any flitter problems in the elevators?I'm half tempted in putting 2 servos aft and dealing with the aft CG problem.Any thoughts?

opjose

Lateral movement of the pushrods causes the flexing.

To prevent this you can fabricate a retainer of some sort to prevent the pushrods from moving sideways, preferably at two points along the fuselage.

This is not hard to do.

Try to keep the wire rod at the elevator shorter than the one towards the servos, for stiffness.

I'm using the same pushrods on the CMP Marathon 24cc and CMP Edge 50CC without problems, and I have not had to resort to the retainers on either, the elevators do not flex a lot, and the rudders on both use a pull-pull setup.

Don't move the servos aft as this will really exacerbate putting the C.G. in the right place.

Retro79

Hellig from Denmark


I was hoping thru this thread, that Simeone can help.
Does anybody know were i can buy body parts for
Cmp's planes? My elevator for broken thru transport and i really want IT to look good again.

Thanks in Advance🙂