PYRC Yak-55 34"

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After many changes and versions, I now have the (hopefuly) final version of my Yak. This Yak-55 has a 34" wingspan and is made from 9mm EPP (or depron) foam and its great for beginners to experts and people who fly giant scale gassers or Super Cubs.

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Features:

Better servo/link geometry
More crash-proof design
Reduced airframe twist
Ultra-Easy assembly
Tab-Slot conctruction
Perfect for RCers on a budget
Added 'floaty-ness'
Better wind handling
Lots of side area
Designed with beginners and experts in mind
Reduced coupling
Awesome harrier stability
Perfect for learning 3D or as a practace plane for experts
Good aileorn trainer **When setup correctly
Easily flown in a backyard or cul-de-sac

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Setup:
This plane is perfect for the 24g 1500kv motor from HobbyKing on a stick-mount. I have tried many servos on it, and this plane does not really care. Below, I put the 9 gram servos for outdoor flying and the 5 gram ones for indoor use. A good ESC is listed below. The battery choice really depends on what you want to be doing. I have used batteries as small as a 500mAh 2-cell and as big as a 1000mAh 3-cell. I would start with a 800mAh 3-cell battery for outdoor and a 800mAh 2-cell for indoor flying, at least for your first flights. It still keeps the weight low but gives you lots of power. Due to the slightly larger size, it still feels really floaty at 8oz. The foam can be picked up at Grayson Hobby. I'm using the 9mm white EPP in the 24" by 36" Sheets. My all-time favorite control horns for foamies are the laser cut plywood ones from Grayson. The holes are perfectly sized for the Nylon Kwik-Links. The 3mm (1/8th in) carbon tubes can also be orderd from Grayson Hobby.

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Links,

24 gram motor
http://www.hobbyking.com/hobbycity/s...trunner_1500kv

Outdoor Servos
http://www.hobbyking.com/hobbycity/s...?idProduct=662

Indoor Servos
http://www.hobbyking.com/hobbycity/s...?idProduct=663

ESC
http://www.hobbyking.com/hobbycity/s...idProduct=6456

EPP Foam
http://www.graysonhobby.com/catalog/...f3d8b8368e7814

Control Horns
http://www.graysonhobby.com/catalog/...f3d8b8368e7814

Pushrod Stuff
http://www.graysonhobby.com/catalog/...ded-p-949.html
http://www.graysonhobby.com/catalog/...be-p-1094.html

Carbon Tubes
http://www.graysonhobby.com/catalog/...0mm-p-938.html

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Attached are some pics, along with the PDF plans that can be downloaded.

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-PinkYakRC

Here are some pics of my completed airframe. I followed the plans exactly, and the foam is 9mm EPP from Grayson Hobby. See link above.

Build log/instructions coming soon!

-PinkYakRC

Build log tomorrow.

Mad skills with the airbrush I see. I gotta try that some day Looks good. Think I might make this for my big brothers first plane. He can practice chasing his kids around the park with it to learn manuevers. My little nieces are fast! Combat kids

Nice info so far.

E.

Originally Posted by RedRanger

Mad skills with the airbrush I see. I gotta try that some day Looks good. Think I might make this for my big brothers first plane. He can practice chasing his kids around the park with it to learn manuevers. My little nieces are fast! Combat kids

Nice info so far.

E.

Thanks!

I did this whole paint job with spray paint. I really want an airbrush though!

Build Pt.1

To start the build you need to print out the plans. It prints out in 15 sheets, and those can be taped together and the peices can be cut out. Once they are cut out, all the plans fit onto a sheet of 9mm EPP foam. You can tape the plans down or pin them to the EPP. I pin them down, I think its just a little faster and easier.

Before you start cutting out the foam, the plans need to be traced around with a sharpie. Make sure to use a stright edge when cutting the foam. A metal ruler is the best thing to use. I use a stright edge when ever the line is more than about an inch long. Try to be fairly neat when cutting foam, the better the peices fit the easier it is later.

After you get all the peices cut out they need to have CF spars installed and they need to be hinged. Starting with hinging, I think the best way to hinge it is to use Welders glue. I wont go into much detail on how to hinge EPP with Welders glue. If you have never done it before, do a search on YouTube for instructions. Basicly you put the peices to gether and run a bead of Welders down the hinge line and use a scraper tool to smooth it out into a nice hinge. Once this dries, bend it back and forth a few times to get the hinge to loosen up and become more flexible.

There are a few ways to do the carbon fiber spars. I like to make the slot with a soldering iron, and just melt a slot. This is fast, and it looks good. On my soldering iron, I unscrewed the tip and found a screw with the same thread. I cut the new screw down to about a 1/2 inch long and screwed it into the tip. The use a stright edge and run the iron down and it makes a great, even slot. Then the carbon tube can be cut to length with a dremel. I like using hot melt glue to glue the spar in. Just run a bead down the length of the slot and press the tube in. I then put two small beads of holt melt glue along each side of the spar. Do this for the wing and elevator.

Originally Posted by PinkYakRC

Thanks!

I did this whole paint job with spray paint. I really want an airbrush though!

Really! All by spray cans! That's fantastic. I am pretty good with the spray paint. To heck with adding to my clutter by getting an air brush! Just takes patience and the right amount of distance and angle to use the spray's right.
Very impressive and looks sharp.
I bought a bunch or Orange Rx's from HK so one of these is surely going into your build. Paint scheme will be done by...of course the nieces for their Daddy

E.

Originally Posted by RedRanger

Paint scheme will be done by...of course the nieces for their Daddy

E.

Nice!

Build Pt.2

Once the carbon spars are installed and the contorl surfaces are done, its time to start painting the plane. The paintjob I did was with spray paint. I used Pactra RC car body paint.

After the color scheme is done, your ready to start on the airframe build. Start the airframe build by glueing the stick motor mount into the horizontal fuse. The slot is slightly undersized; so test fit the stick and you may have to open it up a tiny bit to get the best fit. I always glue the motor mount in with Welders glue. This gives it a little better bond than hot-melt glue.

Slide the horizontal fuse into the vertical fuse and make sure it fits before you get out the glue. I glued the horizontal fuse, and everything else in the airframe with hot melt glue. I need to get flyin' so I dont have time to wait for Welders to dry. When the horizontal fuse is in place, start by glueing the UPPER section of the vertical fuse to the motor mount. DO NOT glue the lower section to the bottom side of the motor mount. Once that glue is dry, finsish glueing the TOP of the vertical fuse in place. Then starting from the tail, begin gluing the bottom ONLY to the back of the wing slot. DO NOT glue infront of the wing slot.

Next you can install the wing into the plane. Use the aileron servo holes and the ailerons to make sure the wing is straight and level. Glue it to the horizontal fuse, then glue the bottom of the vertical fuse in.

Use a knife to split the rudder in half so that it will allow the stab to be slid in. Work the stab into place trying to not hurt the rudder hinges. Finish the stab assembly by putting 2 beads of glue in the area where it meets the horizontal fuse. Then put 4 beads of glue on all 4 corners where it meets the vertical fuse. Put one bead of glue on the bottom rudder piece and glue the top rudder piece back onto the bottom.

Yay! The airframe is complete! That means the maiden is coming soon...all that is left is the electronics install!

Nice build!

Reminds me of the RCPowers Extra 300 I just finished since I'm new at 3D. What does "SFG" mean? It looks like it's supposed to be used as "winglets" for stabilization?

I may start this build if I need to replace my Extra 300...which could be any day since I'm a 3D newbie! If I do, I'll be using BlueCor FFF.

Steve

Originally Posted by StevoRC

Nice build!

Reminds me of the RCPowers Extra 300 I just finished since I'm new at 3D. What does "SFG" mean? It looks like it's supposed to be used as "winglets" for stabilization?

I may start this build if I need to replace my Extra 300...which could be any day since I'm a 3D newbie! If I do, I'll be using BlueCor FFF.

Steve

Steve, I like your profile pic.

SFG means 'Side Force Generator'
For the most part, they are for stability. When the plane does high-alpha (when its pointed up at about 45 degrees and flying slowly) air will slip out from under the wing tips. Then there is low pressure under the wingtips so they cant get much lift and they stall. The SFGs keep more air under the wingtips and it reduces wing rock.

This plane though is so stable it does not even need them.

Originally Posted by PinkYakRC

SFG means 'Side Force Generator'
For the most part, they are for stability. When the plane does high-alpha (when its pointed up at about 45 degrees and flying slowly) air will slip out from under the wing tips. Then there is low pressure under the wingtips so they cant get much lift and they stall. The SFGs keep more air under the wingtips and it reduces wing rock.

This plane though is so stable it does not even need them.

That's good to know. If I build this, then I could use all the help I can get! Thanks for the explanation. Do you have videos yet?

No.... I need a camera man...

Hey Pink, Nice plane! - Thank you.

I'm trying to print the PDF and I don't see a scale to be able to tell easily if it printed correctly.

Any pointers on Scaling, overlap, and A measumerment of one of the parts on a page so I know I have it correct before I run another batch!

Thank you much! -S-

I will add that. but, The wing should be 34"

Any specific questions?