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Jan 28, 2013, 11:04 PM
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General Hobby 40" Yak 54


I recently purchased a General Hobby 40" Yak 54 off Ebay. I have been flying 3D Foamies among other planes for the past year and decided its time to move on to a Balsa plane. With a budget I went for something cheap that I wouldnt be too upset over when (its not a matter of if) I crash it. So I was wondering if anyone has built this particular plane? The instructions are pretty vague, they dont even tell you where to put the Horizontal Stabilizer Servo, not sure if they even have CG listed LOL
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Jan 31, 2013, 12:16 AM
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Ok, so I'm on day 3 of my build and since there aren't any build threads on this plane I decided to make one. Keep in mind this plane only cost $60.00.

The first thing I noticed while unwrapping everything is that the kit is missing a couple parts;
1. Correct size screws to secure the wings
2. Not enough of the 20mm bolts which fit the wings and the axles for the landing gear. So I had to buy another set. Only came with 2 and needed 4.
3. the hinges are kinda crappy, so bought some Dubro nylon hinges.
4. The supplied aileron and tail control arms are pretty heavy and bulky, replaced with CF which I already had.
5. The lightweight aluminum wing spar... Umm its a piece of wooden dowel rod wrapped with grey Monocote. What the ???
6. The canopy is not meant to be easily removed, 4 screws required. More on this below.

On to the assembly:
1.Instructions are minimal, the instruction book itself is a copy of a copy so the pictures really don't provide much insight. Small details such as what the laser cut pieces of wood are for give absolutely no explanation. I still don't know, the mystery continues
https://www.rcgroups.com/forums/show...=5497980&stc=1
2. Re-glue the entire fuselage! It didn't take much manipulating to pull apart the motor mount on the nose and in general the entire thing just didn't feel very solid.
3. Once I glued together the tail assembly it appears some of the control surfaces aren't exactly straight, ie. the rudder has a slight bow as does the horizontal stabilizer. Nothing to keep it from flying but I cant wait to see how I have to trim it once in the air. More to follow on that.
https://www.rcgroups.com/forums/atta...mentid=5497996
4. While installing the wings, I first put in the 20mm machine screw in one wing so I could use the other side to access the phillips head screwdriver. Easy enough except there are still two other pre-drilled holes to screw down, however none of the screws provided seem to fit. They are not threaded so I'll just have to get some small wood screws. The other side will be much more fun to screw on.

Things are coming together now but the hatch on the bottom of this plane is in no way big enough to accommodate any battery you would need to fly for more than a couple minutes. I plan to use a 3 cell 1000 mah+ battery. Going to have to make a removable canopy.

So thats where I am at this point, the removable canopy is made and secured with earth magnets from Harbor Freight. So far I had to buy the following;

Extra 20 mm screws for landing gear..$2.75
Nylon hinges (15 pack)....$5.00
wood screws (4)... $1.00
Smaller control horn connectors....$5.50
Piece of balsa for removable canopy...$3.79
Rare earth magnets...$2.79

I did say this was a $60.00.. plane right?
Last edited by enrico0273; Jan 31, 2013 at 09:49 PM.
Feb 04, 2013, 10:34 PM
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So the Yak is built and I have flown it a couple times. This thing is fast and does not like to land very slow. Using flapperons I was able to land it pretty well. Initially the battery was as far forward as I could get it but that made it too nose heavy. So I moved it back about 2 inches and it flew much better, However, I think its way too overpowered and nose heavy from the motor. Also, you need to cut a vent in the tail section for air to escape. Otherwise the canopy gets blown off from the inside air pressure (as I found out).

Setup Now
Motor: Optima 480 Brushless 1020kv 275w
Propeller: 11x 3.8
Battery: 2100 Mah 20C
AUR is still just a hair under 2 lbs at (1lb 15.4 oz)

Planning to put in a 150kw motor I have and stepping down to 1000Mah 45c packs. running a 11 x 4.7 prop. will update once i fix my landing gear
Last edited by enrico0273; Feb 05, 2013 at 12:01 AM.
Feb 04, 2013, 11:03 PM
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Yeah, that is a 115g motor, and heavy for a plane that small. General's website says the plane weighs 700g, which sounds a bit light for a 40"ws plane.

I'm not sure what you mean by a "150kw" motor, but I would think something in the 70g range with about the same kv as the motor you now have, would work fine. With this new motor, I think you might find a standard prop 11x5.5 or 12x6 would be a better option than the slofly.

If your plane w/battery runs 1000g, then I think you should be using nothing smaller than a 1300mah battery.

Hope this helps.

Steve
Feb 05, 2013, 12:05 AM
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Thanks for the response Steve, I plan on using a 1150kv motor I have laying around. Basically I just want to see how well she fly's with proper weight. If it fly's ok I'll go ahead and get a 190-200W 70G motor.
I guess on the plus side, I have a descent motor for a 42" AJ slick when they are back in stock
Feb 05, 2013, 11:45 AM
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Yes, and another consideration would be the 41" Edge. That same 70g motor would be a perfect fit. I had an orange one, and it is a great flier - great entry level plane.

And, yes, the motor you now have is a good fit for the 42" Slick. I had one of those also. It always shocked me when I had the 41 and 42 next to either, how much bigger the Slick looked.

Have fun.

Steve
Feb 18, 2013, 10:25 AM
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Just wanted to update this thread one last time. I repaired the plane after the landing gear was torn off and put in a much smaller motor at 59g and about 150 watts. It was plenty of power for this plane but was still nose heavy. After another rough landing the plane was back up with little damage and a smaller 3cell 1300 Mah battery. Upon takeoff it porpoised a couple times and took a final nose dive (most likely from a loose horizontal stabilizer servo) . The damage is way more than I have time or desire to try and repair so I'm done with this one.
I did get a couple flights so as far as flight characteristics I found it to be pretty slow doing aileron rolls but had plenty of tail authority, I'm sure a more experienced pilot could knife edge this plane all day. The CG is tough to nail down but I'm sure it can be done. This plane really doesn't have that much wing area and although I had the flying weight at around 1.6lbs and CG as recommended it was hard to land smoothly.
Bottom Line- Pay the extra money for a plane that is set up a bit better and dialed in out of the box.


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