EF 47.5 yak
 

Guys, I now have a EF Yak. It weighs 43 ounces with a Evo 2170 4 cell. I'm having alot of wing rock while trying harriers. The CG can go a little more aft which I will do. Anyone else dealing with this and if so any suggestions in correcting it? I watch the videos and it seems to have no wing rock. Just need some suggestions.
Thanks!

RE: EF 47.5 yak
 

I just finished putting 5 more flights on my Yak bringing the total flights to over 75 so far. I love my Yak and it flies very well. I am using the 3S setup and I have some wing rock upright. I have found there are several "sweet spots" to get it rock solid and it just takes getting used to. I have found that my setup seems to harrier best in a gentle pitch-up attitude or full-up elevator and an almost-hover attitude. Inverted harriers for me are rock solid. I guess the best thing would be to move the battery back and practice until you figure it out. Have fun with this great plane.

RE: EF 47.5 yak
 

Thanks. I can say that inverted has little to no rock. I ordered a couple of 3 cells to try out along with 2 different props. Now it has a 12-6 on it. I'm going to try a 13-4 and a 12.25-3.75 and see how they work. How do you like the 3 cell set up? Still plenty of punch?

RE: EF 47.5 yak
 

I've got the same bird w/ the 4 Cell, I moved my battery back pretty far to get the cg correct for 3D. The battery is about an inch behind the carbon wing tube for my type of flying. Elevators and everything else are pretty solid. But I'mrunning a heavier motor and esc set-up. Axi 2820/10 motor and Phoenix 60 esc. What set-ups are you guys running? I found that the Yak likes the weight of the 4 cell over the 3 cell. I feel like I can do more with it. But that's just me. Good luck.

RE: EF 47.5 yak
 

I have the super combo from Extreme Flight. (The 4 cell combo)

RE: EF 47.5 yak
 

I like my 3 cell combo. I have the recommended Torque motor, 45amp CC ESC, 2170mAh 3S 25C lipo, HS-65HB servos, and 14x7e APC prop. It will pull out of a hover with authority and not stop until I pull back on the throttle. I have been very pleased with this setup and feel very comfortable with it. I used an APC 13x6.53 on it first, but after trying the 14x7e, I won't go back. The 14x7 gives me much more power on the vertical and yet it slows down quickly when I want it to. Everything comes down very cool even after a more aggressive flight with the power. Of course, I like a "lighter" feel on my planes and still have all the power I need.

RE: EF 47.5 yak
 

I agree about the light feel. I got 2 Evo 2170 3s batteries today but it's way too windy to go fly. I'll see how it goes. I'll be trying different props too.

RE: EF 47.5 yak
 

Hey just a question which one of the rimfire motors would make this plane insane, the rimfire 35-36-1200 has a 1200kv max constant watts of 666w and *****g out at 815 watts! its two ounces lighter than the Torque motors too.

Thanks jeff

RE: EF 47.5 yak
 

Jeff, Let us know how that goes if you use one.
I bought some Evo 3C 2170's to try and I like the 4C Evo 2170 much, much better.

RE: EF 47.5 yak
 

Hey thanks, i work at my LHS and am picking mine up on friday, I just didnt get the torque motor so i wil try this one with a 4c set up.

RE: EF 47.5 yak
 

Jeff, That sounds like the same specs as my Axi 2820/10. I'm using 4s w/ 1100 kv and around 840 watts. I'm also using the APC 12x6E prop. No clue what my rpms are. You'll love that setup.

RE: EF 47.5 yak
 

Hey thanks I will give it a try, i just want some serious vert. i think it will be even better with a 4 cell, are you running a reciever pack, or you runing everything with the main battery?

RE: EF 47.5 yak
 

Everything off the main battery. My set up with 4 cells gives all the vert you need so you'll be happy. After trying a 3 cell I highly suggest using a 4s battery. The 3s just is'nt enough after seeing the power from the 4s, it's a monster. Just my opinion.

RE: EF 47.5 yak
 

Same here, using a Castle UBEC

RE: EF 47.5 yak
 

See i have never used a BEC in anything so im not sure exactly how they work.

RE: EF 47.5 yak
 

Also which speed control are you using?

RE: EF 47.5 yak
 

I think it's called AirBoss 45amp. I usually would use a Castle Creations myself. Thats with the Torque motor.

RE: EF 47.5 yak
 

Castle Phoenix 60 ESC

RE: EF 47.5 yak
 

I would do the castle 60, Is it a good idea tho to use a BEC?

RE: EF 47.5 yak
 

Use an external, the one built into the castle 60 esc is good for up to 3 cell.

RE: EF 47.5 yak
 

Ok what exactly does a Bec do?

RE: EF 47.5 yak
 

The BEC (battery eliminator circuit) takes power from the battery and delivers it straight to the receiver and servos. The esc then only has to worry powering the motor. It's used any time you run 4 cell or greater. The built in BEC on the ESC can't handle that kind of load.

RE: EF 47.5 yak
 

Well the rimfire motor pretty much took my plane into orbit, i mean it needs to be powered down, the only downside to it is it exploded on me in flight but I didnt loosew the plane!

RE: EF 47.5 yak
 

I had a similar issue with my yak last week. The whol time that I've been running 4 cell I only fly with 25-75% throttle. I decided to do a low altitude,high speed pass ( I was at the red bull air races the week prior, so I was inspired...) Went full power and there was so much torque that I twistedthe motor mount. Luckily there were a few splinters holding it together and I was able to land safely. So now that the parts are here I'm gonna see if there's a way I can beef it up so that doesn't happen again.