I really love YAKs and their big round engines. I have been looking at the EF YAK for a long time and finally bought one. I have built 3 other 50cc size planes the 3DHS 87"SHP, the 89" Slick and a Peak Models Pitts M12 biplane.

The plane arrived in 2 huge boxes as expected and was well packed and undamaged. Construction is straight forward for the most part. The manual says there are no axles or wheels supplies but happily that is an error. The axles are quite long though and I need to Dremel them shorter. I used Gorilla glue to mount the hinges on the control surfaces and HS7955TG servos all around with SWB arms as recommended. Mounting the Hacker Q80 motor was a bit of a challenge as the firewall has a large hole in the center for a carburator or other some such nonsense. It turned out OK though as that is my primary source of cooling air for the batteries...

I programmed my new JR 9503 using the two servo elevator option. It is easier then using the DX7 and mixes. I also like the timer starting with the throttle stick. The AUW with 2 6S 5000 packs was about 19lb. I did not have the Castle 160HV controller so substituted an 85HV in the package for weigh in. I added the receiver veocro and straps after weigh in too.

Credit to GB for the outside shots and video. It was not a good day for pictures or video.

Here's a video. Haven't watched it yet. The Q80 is REALLY powerful. Most of the flight was made with 1/2 throttle. After 5 min batteries were at about 50% charge.

Extreme Flight 88" Yak 54 (4 min 47 sec)

Oh boy he got the really bad landing. Sorry for that. I promise to do better!

Yes, each landing got better and better.

Let's try to get some sunny wx video.

gb

I like the Yak 54 especially in that color scheme. Guys I fly with call it a Yuk 54 but I like it.

Very nice feathermerchant! What kind of Watts and Amp draw are you seeing with that set-up? Looks like it has some serious power.

Originally Posted by EXTREME FLIGHT

What kind of Watts and Amp draw are you seeing with that set-up? Looks like it has some serious power.

+1 curious to know myself.

James, how was the throttle transition? Any lag?

Thanks!

Tim

I did not feel any lag. It felt extremely powerful and responsive.
I just downloaded and saved the log. How do I view it using the castle software but not connected to the ESC? I answered my own question. The Castle log viewer installs with Castle link. Thete's an icon on my desktop.
It showed a max power of about 5200W as I recall. The ripple was pretty low too but the ESC temp was 121 peak on a ~50 deg day. I have some cooling work to do. I already have some ideas. As I expected, I loafed around at ~50-60%% power most of the time.

To EXTREMEFLIGHT - I apologize for the Extremely crappy landing. The others were much better I promise.

Sweet! I love the sound of 50CC electrics! AKA 5KWs!

Talked to Aero-Model and they said to use the default motor timing, PWM frequency and motor start power. They also said the clucking noise is known to be caused by logging data. Turn off the logging and it goes away.
Talked with Castle and they concur.
They did say that it is important to monitor ripple levels calculating the % by dividing the average ripple by the average voltage from a flight. <5% you're OK. >5% you need to take action. Shorten battery leads, add capacitors, replace batteries, etc. Batteries exhibit more ripple as they age.

I am feeling badly about including that landing. That was the aircraft's first and the only one captured. The subsequent 4 were perfect. Due to the poor lighting conditions, the video equipment had been put away, so, the nice landings were missed. If feather does not fire me, we will get better examples soon.

Here are a couple of feather's more typical landings.

Landings (0 min 21 sec)

gb

We all bounce a landing every now and again, not a big deal. Thanks to you guys for posting the details of this set-up and video. Lots of us really appreciate it.

I'd like to have one of you Extreme Flight experts fly it and tell me what you think. Will you be in the DFW area soon? What is your flyin schedule?

I dislike using a wrench to remove the canopy after every flight. So I 'made' these. Starting with the supplied socket head screws, I drew a 7/16" circle on some scrap 3/32" ply. Then I drilled a hole for a tight fit to the bolt head. Next, I laminated another piece of scrap 3/32" ply and cut around the circle with my jigsaw, leaving a generous margin. The hole was off center some but that doesn't matter. The Pliers and scrap wood and blind nut were used to press the bolt head into the hole. I used medium CA for laminating and gluing the bolt head. Then to the drill press where I mounted the screw and spun the whole thing while using a sanding T braced on the drill table to slowly true it up.
The black finish is 2 coats of big black sharpie. I did not add knurling because I don't need to get the bolts really tight.

Got 3 more flights in today in perfect weather conditions. I made a cooling mod by blocking off the rear of the 'carburetor (or is it oil?) scoop'. That forces the air through the firewall openings and over the esc and batteries. They still get warm but the motor does not get warm at all. Temp was about 65degF. Still barely tailheavy with packs as shown. I may add a CF spinner for ballast and good looks. Lands super easy. KE is great with almost no roll coupling.
The wheels are freezing up on the axles now after a few landings so I need to hit the axles with a little file or some sand paper. I did one at the field with borrowed tools then flew again and sure enough the other one tightened up.
By then it was time to go.

Looks great feather!

Before mounting the wheels, I always put a light coat of oil on the axles. As long as your wheel collar is not to tight, they won't freeze up on you.