Extrem Flight 91 yak

[orthobird]

I flew my EF 110" Yak for years with it open, DA120 stock mufflers and no problems with over heating or anything. It also shows off that expensive motor pulling it around.

Awesome!!! i like that!! i have two yaks, one is a the EF 91" yak and the other is a Bill Hempel 40%, both have the closed Cowl, both have baffles, the Bil Hempel Yak with the 170 runs cool and great, never a problem. The EF yak 91" with the DA 70, runs hot in the summer, especially with 3D flight. so i was considering opening it up.

 

[Hazmat1]

I have a 91" EF yak with a GP61 and smooth pipe. What a plane. Probably one of the best all around planes in its size. They are built great. EF did a great job in the desogn.

 

[orthobird]

i agree with you, that 91" yak is very well built.

 

[orthobird]

Was able to open the front of the cowl last night, and i also installed the MTW 110 H canister with the 2 in 1 header.

Maybe today i will get to fly it.

I will post telemetry temps...

 

[orthobird]

I was able to get her airborne today, and wow!! she is one quiet bird!!
The 25 x 8 W prop was turning, peak, 7110 rpm.
got temps also, once i get my Tx, i will post those as well!!

 

[orthobird]

Here is the telemetry data:

date: 3/28/15 (2nd flight of the day, made one modification, removed the Jtec stock muffs and installed the MTW 110H cans, rear dump with DA 2:1 header
Engine: DA 70 twin
Fuel / oil mix: 40 to 1
altitude: 260 feet
ambient temperature: 58 f
prop size: 25 x 8W falcon
air frame: extreme flight yak 91"
radio system: Jeti

data:
1. high temp during flight (not after landing): 239 F (right cylinder), left cylinder 333.8 F
2. temp range right =181 - 239 F, left cylinder = 249-333.8
3. rpm range 2320-7200
4. rpm max during flight 7200
5. rpm max on the ground= 6850
6. Rx voltage = 8.23 at start of flight, and 8.19 at end of flight (lipo batteries 2s, x2 batteries, 2600 mah each battery)
7. Rx voltage minimum during flight = 8.16