Electric QQ 69" Yak

bdavison

Senior Member
Should have some video of it this weekend.

The plane has had a successful maiden flight, but due to weather it hasnt been up since the maiden.

The powerplant is phenominal!!!

Scorpion Brushless Motor, Castle 85HV ESC, and 8S Polyquest lipos turn it into a ROCKET plane. It has STUPID power for sure.
If all goes as planned, we are going to try to get QQ himself to fly it at SEFF to see what he thinks.

More pics and video are coming soon.
 

ben_beyer

Junior Member
I'm thinking I need to get a new cowling for mine and do this. Probably go with a Hacker A60-20S on 8S with an APC 17x10 (or is it 17x11?).
 

bdavison

Senior Member
I dont know about the hacker, but I can tell you it is HOT with that Scorpion on it. Its definatly got more power than a 1.20 glow engine would have. If we can find a wattmeter, ill try to get some readings...Im guessing its well over 2000W.
Its got so much power, the first time edge5foamy went to take off, he shoved power to it, and it pulled the prop off.

Its insane.
 

bdavison

Senior Member
We've all seen QQ yaks, maybe even flown one before. Some of you may own one. Me personally, Ive seen and flown some of them...but never built one. Ive read all the build threads, dreaming one day to get my hands on one. Then up pops Edge on my Instant Messenger saying...."HEY, guess what" "QQ is sending a yak for an electric conversion".

SWEET!!!!

So a couple of days later, the yak arrives. Edge and I open up the box . Immediatly this bright light eminated from the box as we heard angels singing in the background....Just Kidding... Ok, lets be honest. The QQ yak is the olympic gold of airplanes.

So as we are of course fondling all the parts of the airplane, browsing the manual, and admiring the ball link hardware....its time to get to work.

First off, since this is a E-conversion, and a plane that is going to be demonstrated (er...flown like it was stolen)..it needs to be strong, and good looking. You cant have raggedy covering and a hack job on a demo plane. It has to be "golden". So we decided that the build would spare nothing. Everything would be done correctly, and with an extra degree of precision.

We cut the ultracote from the wing saddles and ironed it down to make sure it doesnt delaminate in flight. Also cutting and ironing down the covering around the horizontal stab pocket.





Next we fitted the horizontal stab, cut the covering away, and trimmed everything to fit PERFECTLY. Measured about 10 times to ensure that everything was perfectly straight. Luckily QQ's excellent quality kit, was so straight that we barely had to do any adjustments. The left stab required a 1/16" shim and that was it.
 

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bdavison

Senior Member
Yesterday we installed the elevator and rudder servos and linkages. There is still more work to be done on them such as adding washers to the rudder ball links to keep the links from popping off, locktite on the nuts, etc.

The elevator servo install and linkages were a fairly easy construction. QQ supplied some excellent servo arms for the servos. The servo arms are attached to a standard round servo arm that comes with the servo using 4 small bolts. The small bolts are not supplied in the kit, so you will have to purchase them. We got the small bolts from radio shack.

You do need to add a washer (not supplied) to any balllinks that are not completely enclosed. This prevents the balllink from popping off the ball in flight...which would be BAD. Its a simple fix that can prevent a potentially fatal problem.
 

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bdavison

Senior Member
The rudder linkages are a little more difficult to install, but due to the nice hardware...its a pretty straightforward install.

It should be noted that HS-5625MG's are a perfect fit for the servo bays. These nice digital servos should supply more than enough torque and power to the surfaces. With the 6.0V that we will be supplying to them, they can produce 131oz/in of torque.

Geometry on the stock installation is good. Freedom of movement on the rudder, with no slacking is achievable with the stock setup. As usual the wires must be crossed in the fuselage for proper geometry. QQ supplies all the cable and crimps with the plane. When you get the yak, it will have some "new" balllinks for the rudder. Make sure you use these as the old balllinks are improper I.D. for the linkages.

We still have to add the retaining washers to the servo arm balllinks, and locktite to the nuts, but these pictures will show how it all goes together. Again....the servo arm is supplied in the kit, and is attached via bolts (not supplied) to the stock servo arm.
 

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bdavison

Senior Member
The yak is completed with the RX, motor, ESC and batteries installed.
The Scorpion motor is installed in a nice stiff motor mount. The Castle Creations 85HV is mounted underneath the firewall box. Two lipos to power the motor, and one smaller lipo connected to a Castle Creations BEC to power the rx and servos. Servo draw on this setup was measured at 1A max.

Lipos are connected in series to the ESC via a custom Y harness that I soldered up.
 

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bdavison

Senior Member
Both Edge5foamy and I have flown this plane. Power is impressive, and is certainly more than enough for any type of 3D aerobatics. The plane is VERY quiet in the air. Flighttimes are around 7-10 min so far.
The equipment runs cool, the motor just slightly warming up after a long 3D flight.

Its really nice having instant throttle response on a plane this big. Its the first time I ever flew anything larger than .60 sized in electric. I must say, its a huge improvement over the responsiveness from glow. If you guys havent tried a "E" setup on the larger planes, Id recommend it.

Hopefully we can get video of it soon. We've been having technical difficulties with some of our cameras. Also look forward to seeing onboard video coming soon too.
 

ben_beyer

Junior Member
How many maH's are the LiPos you're using for the motor?

I have this airplane but it's set up for glow. I'm thinking I need to get another one for E-Power.
 

bdavison

Senior Member
Two Polyquest 4cell 4350mah lipos connected in series for a 8cells
One Polyquest 2cell 2150mah lipo for Rx and Servos.

The two 4cells are connected in series to the ESC which supplies power to the Scorpion motor.

The Single 2cell is connected to a CC 10A BEC which provides power to the Berg 7 rx and the Hitec Digital servos.

Here is a wiring diagram:
 

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ben_beyer

Junior Member
I talked with another guy that's converted this plane and he's getting 1987 watts off of a Scorpion 4025-12 with a 6S Rhino 4900maH LiPo. The airplane weighs about 8.5 lbs. so he's getting about 234 watts/lbs. Flight times are 10 min. with mixed aerobatics and he's only using 80% of the pack.
 

bdavison

Senior Member
Im surprised that 6cells would put out that kind of performance. True testiment to the scorpion motors.

I flew edge's yak, and Ive never seen anything with that kind of power. It was like we strapped a turbine to it or something, the vertical was insane. We never found out exactly what the watts were on it, but if hes getting 1987W off 6cells, Ive no doubt that edges setup is well over 2000W.

The scorpion motor is the ticket for these bigger airplanes. I just havent seen anything that can touch them. Ive seen that some of the e-pattern pilots are switching from hackers and axi's over to the scorpion motors....and for good reason. They are HOT!!!
 

ben_beyer

Junior Member
Yeah, I'm about to pick one of those motors up. They seem to have performance and efficiency.

Do you remember what Scorpion ya'll put in the QQ Yak?
 

Edge5foamy

3D or DIE!
Ben, it is a 4025-16. I am running it on two 4s 4350mah Li-Pos, but this has made it a little on the heavy side. Here pretty soon I am going to go to something like 4s(heck maybe even 3s) 3700mah Li-Pos.
 

bdavison

Senior Member
Didnt feel heavy to me...LOL.
What did it weigh in at edge...its was a tad over 9lbs wasnt it.

Im seriously considering building a new sebart katana 120, and putting the same setup edge has in his yak. That scorpion is just stupid power in it. Sebart is recommending a 10S setup, but I have no doubt that that scorpion will pull it better on 8cells than that setup they recommend on 10.
 
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