Kris' GP Yak-54 buld thread

[KrisW]

And now we trial mount the engine. .

Complete with JA Pitts muffler the thing just slides into place.

[KrisW]

And then we add the cowl. Mocking up the cooling air outlet hole int he bottom of the cowl was easy. The cylinder is 2.9" in diameter, and 1.5" back from the thrust washer of the crankshaft. Merely measure back 1.5", make a drawing of a 3" hole, extend it back another 3" so you can get the Pitts muffler into the hole as well, and cut it out. Slide it on the plane and you are DONE. Escept for a minor bit of interference from the carburetor needles, this thing just drops into place. A couple of small holes will suffice to get the needles to clear.

[KrisW]

	Quote: Originally Posted by tl3
	Kris, Could this thing be modified (without major re-construction) to accept a tuned pipe? I have a 3m 170 and pipe I haven't found a buyer for - now looking for something to fit around it. t

Tl, this plane has a foam belly pan, and the "box" of the fuselage leaves almost no room for anything underneath it. going straight thru the center of the fuselage is possible, but you are going to have to do some major surgery and plumbing to the pipe to fit between the floor of the fuselage box and the wing tube socket. I was going to install a canister muffler that is 2.5" in diameter, but there is not enough room internally for it.

The distance between the wing tube and bottom of the "box" is a mere 1.6", and to the top of the foam belly is about 3". You'd also have to cut out a couple of formers to make things fit. (see pic)

I do NOT like where they mount the fuel tank. it's in front of the wing tube, lending itself to a shift of CG while flying. I'm going to explore mounting the tank beneath the tube. I think I can hollow out the foam belly enough to wedge a 16 ounce DuBro tank in there, or if that fails I'll just mount one above the wing tube, and modify the structure slightly to get it to fit. I'm not really concerned with the inside of the canopy area being "all pretty. . with the nice looking wooden bottom plate, IP, and pilot. It's easy to add a flat balsa IP without the floor being in place, and pilot figures are easy enough to mount up as well. I'll do the tank installation later today, and take pics of it.

[Texx]

Great building thread so far Kris! I like all the fine details that your are letting everyone know up front which will ease any future builds! I can't wait to see your next progress posts! Keep em coming!

[KrisW]

Time to install the fuel tank.

Since the fuel tank mounting plate came loose, I decided to use it for this installation by moving it to the top of the wing tube.

A fitting of the tank in this location revealed minimal surgery necessary to wedge the tank between the two formers in front and behind the wing tube. Simple notches were cut on the front half of the top fuselage plate, leaving material to mate properly to the fuselage formers. Then, a plate with a slot in it was fabricated from 1/8 lite ply, and mated to the tank mounting plate.

This assembly was glued to the rear former and wing tube socket using Medium CA, then two screws added tot he rear plate to secure it firmly to the fuselage former. Then a piece of 3/8 hardwood tristock was placed across the front fuselage former, under the front of the tank mounting plate, and CA'd into place. See pics for details.

The tank nestles snugly in this spot, being held in place by the front former and wing tube/mount with almost zero up-down movement. A simple single nylon strap around the tank can hold it in place. As seen in the pics, there is plenty of room for the fuel lines to clear the front fuselage former, then be routed forward and down to their proper locations.

This is a 16 ounce DuBro tank, Not the 24 ounce tank supplied with the plane, which would not fit in this location. 16 ounces of gas with a 50cc BME gives well over 15 minutes of flying time. you'll get vbored trying to run the gas out of a 16 ounce tank with a BME44 on the nose.

[KrisW]

Hatch Mods to clear the Fuel Tank:

Cut out a 3" wide and 1" tall slice of the "IP" in the front of the hatch.

DONE

[JustPlaneCrazy]

Looking good so far, keep them pics coming.

[SleepyC]

Yea man.. good work!
Like it!

[YaKs are BeSt]

so are there really 4 slots for rudder servos?

what kind of crazy kit maker would do that?

[ShortBus]

	Quote: Originally Posted by YaKs are BeSt
	so are there really 4 slots for rudder servos? what kind of crazy kit maker would do that?

Someone who knows what their customer wants maybe????


The ability to either use two less expensive servos in the tail or tray or ONE expensive servo in the tray up front or two less expensive servos in the tray

[KrisW]

ACTUALLY. . . .

The two upper slots are for ELEVATOR servos, the two lower ones are for the Rudder. You run one rudder per side with a push-pull 4-40 rod to the rudder horn on each side of the rudder. The elevator servoes are mounted on line with the stabilizer/elevator, instead of inside the stabilizer itself. It makes for a longer pushrod, which I am going to show how to fix a little later tonight.

[KrisW]

OKAY. . Radio gear installation.

Judging from the poll, it seems there is pretty much equal support for any of the digitals I have listed, though the 5945's seem a little more popular. So. . Servo setup is going to be:

8411's on Ailerons
5945's on Elevators
5995/5955 on rudder (1)
JR 507 on throttle (gotta represent the low-buck stuff here too)

Receiver is going to be a JR 945s
Transmitter is going to be the 8103 . .Again, because it's "low buck" approach compared to the pricier 10X, and since it has a good amount of support in the poll. I'll back the plane up in the 10X. . "just because", but I really can't see any mixing benefits to the 10X unless I want to get into some seriously silly funfly mixing.

This setup, to me, represents about the limit of the "sports modelers" cash input for a model of this size. On the market you can find used 8411's and 5945's all the time, and if you want to use a single rudder servo and avoid the headaches of a dual-servo setup you'd need something stronger than a 190-oz torque servo IMO. the average mdeler would then spring for an 8611A or 5995/5955.

In reality, given the softer deadband of most high-end coreles servos out there, this plane would do great with an entire set of HiTec 945's or JR 2721's or equivalent, since binding during movement would be less prevalent. Anything in the 100-120 ounce range would work perfectly, especially on a 6 volt setup.

Thanks for everyone who voted in the poll.