A fully 3D capable plane, unique Yak55SP looks, brushless electric motor powered, AND fits back into its box for travel? A dream? NO! Its here, Extreme Flight RC has done it, and did it well.

As most know, the 3D electric freight train has arrived for some time now, and just keeps evolving more and more. This Yak actually is designed to come apart quickly and fit into its own travel case with handle. Amazing, plus, you can purchase just the airframe, OR the combo deal with brushless motor and gearbox, with prop and ESC. Then all you need to fly is your own 3s Lipoly battery pack, 4 Hitec HS55 or equivalent servo's, and a 4-6 channel RX. Lets get to the model.

All in box

All out of box

Once the Yak showed up I couldn't wait to open up that box and see how it all fits together. I was greeted with a great covering job, and all the goodies to make a unique 3D flying aircraft. It builds pretty quick (its an ARF) and looks stunning.

Top of wing shows aileron servo's

Bottom of wing shows aileron servo's

Side view

Aileron linkage closeup

First you mount the 4 servo's in the wing, splines to the rear, then the control horns, be sure to mount the correct ones here, If you put the large ones in you wont be able to get the wing off or on, so use the smaller two horns. My gripe here was the rods had a pre-bent z in them for the servo, which is great, BUT the way it was bent put a lot of pressure on the servo arm, and it would not come down to the aileron linkage, So I adjusted the Z bend so they fit and where still tight.

Control horn in place

Tabs on bottom of stab

Control horn in rudder

Rudder mounted

Now find the pre-hinged elevator setup and install one of the long control horns there, and using thin CA on that flip it over and install two small tabs with holes into the bottom of the stab. Be sure they are 90 degree's from the stab, these need to be straight. They will be used to screw it to the fuse. Finally install remaining long horn onto the rudder, then hinge the rudder and with thin CA glue it on.

Cutting out the wing area

Elevator cutout

All done

Lay the fuse down on a flat surface, grab a sharp knife and cut out the wing and elevator/stab area's. I found it easiest to cut out one side, then go through that same side to perfectly cut out the other side. Do lay it onto something you can cut on though.

Guides all installed

Now is the fun part. Find the vertical pieces in the fuse, then cut the covering away in little slots to be able to glue in the pushrod guides. Its a little fiddling, but make sure they are fairly in line, and straight so the pushrods go smoothly, you can also get a drill and make the holes the next size larger so there will be no problems.

Plastic discs glued on

NOT LIKE THIS

LIKE THIS!

Put the wing into the fuse, I used a twist drill for this, but you need to take a small drill bit and go through the mounting tabs and drill holes through the fuse. After that glue the little plastic discs onto the opposite side of the fuse from the wing mounting tabs. The wing screws will screw into these to hold the wing on.

Do the same for the stab, but note! The manual says for the stab to be all the way back in the slot with enough room for elevator movement... this will not work as the elevator pushrod was too short in my kit, so I simply moved the stab far enough forward I could get the setup to work.

Covering cut away and wedge in place

Right Thrust

Screws in place

Prop and spinner on

Grab the fuse again, slit the covering above the area the motor goes on, then find the little block of balsa, and use some sandpaper to sand it down to a wedge. After that put a small drop of CA on the back of the wedge and glue it onto the left side of the fuse on top of the covering. Install the motor and gearbox, hold against fuse and drill and install the two screws to hold it on. Manual says you need about 2 degree's of right thrust, I eyeballed mine and its pretty close.

Cutting out the wing area

Elevator cutout

Tailskid

Use your razor knife to cut the covering out of the landing gear slots, put the wire gear in place and put a zip around them as the manual says. Slide on the wheels and put the keepers on, the tail skid simply goes into a hole at the back of the fuse, put a drop of CA on it and your landing gear are done. They say not to install them if flying from grass, I have had good luck, but it probably all depends on your mowing job! My tail skid is loose, but does not fall out, its been working fine however.

Electronics

Rudder control

Elevator control

Aileron setup

Finished

Completed

Now its time to solder the ESC to the motor, if you have never had a brushless motor before, simply solder the 3 wires to the motor, then when you run the engine if it goes backwards, simply reverse two of the wires and it will spin the correct direction.

For the RX, you cut a hole in the bottom of the wing and put the RX inside the wing and tape up the hole. If you plan to take the wing off and on put a short extension on the throttle to the ESC onto the fuse so you have a good spot to disconnect the two without having to open up the wing each time.

Finally, install the pushrods, double check on the elevator and rudder pushrods that you do not get them mixed up. Make your 90 degree bend on the control horn end and put the small wood discs there to hold them on. I put a tiny dab of ca on the ends of the wires to hold them on. Same goes for ailerons.

That does it, set your throws, check your CG, charge your batteries! I put some Velcro under the wing as the plane did not balance right with the pack in front of the wing. So far I think the best compromise in stamina and weight is the 850-1050mah lipoly 3 cell packs. Keeps the plane light feeling, and easier to balance, the 1320's are a fair bit larger and heavier packs.

You can fit over 7 packs in the large one

The Bunkers

Just for added safety while storing and charging my lipoly packs, since I don't have a garage where I am living, I got a couple Battery Bunkers to put my packs in while storing and charging. The Lithium packs can literally burn up inside these bunkers and will not start your house on fire! Now you can sleep easy. We have all seen what these packs can do. And for the price can not be beat. Contact Kevin at www.batterybunker.net to find out more.

POSING

Bottom

Side

Corner

Corner

Front

Side

The little Yak flies quite well. I played with battery position, and ended up going back to the original location in front of the wing. It was just more predictable there.

With the cg as setup, it flew well, harriers upright and inverted were a piece of cake, it has some coupling in knife edge, but was easily mixed out for ease of mind, but high alpha knife fly by's are awesome. Rolls were blinding on full throw, so keep that in mind on maidens! 4 point rolls were also fun and easy.

The yak hovers with ease, torque rolls are an easy pace to keep up with and very predictable, rolling harriers were much easier with the battery in the stock location as well. The rudder is very powerful, and flat turns are a lot of fun. Mine felt a bit on the edge of under-powered, hover pull out is decent on a fresh charge, but later in the pack, it does not have the punch I like to have to get out of trouble if something goes bad.

Flat spins are as easy as full throttle, full rudder and full or less of up elevator. Just a tad of aileron and sometimes I got mine to climb while spinning. Loops and rolls are obviously possible. The Yak does great walls and parachutes! Very fun!! All in all its a fun plane, and definitely is different from all the extra's and edges out there.

Like to thank Kelvin Buck for helping with the video and pictures.

Lets put it back in the box

Yes, it fits in there

Remove wing and servo arm screws

remove servo arms

Be sure to remove lower screws

Remove right side aileron linkage

Slide wing out

Put wing in box

Remove screws and control horn linkage for elevator and slide out

Put elevator in box

Remove zip tie and gear

Put fuse and gear in box

The more I flew the yak the more I enjoyed it, if you watched the video you can see I did a little strength testing landing (and crashing) on my car. I really was surprised by the amount of punishment the model could take. A little gripe of mine, is Id like to have a bit more power for getting out of a bad situation, its enough to pull out of a hover, but just my personal preference. Other than that, if your in the market for something different, this is it.

Extreme Flight RC
Phone: 770-887-1794
www.extremflightrc.com

Donalds Hobby
Donald's Hobby Center, Inc.
1025 S. Collegiate Dr.
Paris, Texas 75460
sales@donalds-hobby.com

Battery Bunker
www.batterybunker.net
(760)-247-6980