3DHS 91" Yak 55

[49dimes]

These aren't terribly exciting as all I've done is hang the motor, hopefully over the next few days I'll get the ignition mounted, throttle linkage connected up, and choke figured out. Gonna be too cold to fly this coming weekend, so I'm not in a huge rush to finish it all up.
The included standoffs with the EME work great. I had to add one washer in addition to each one to get it to be the right spacing, and had to get some longer M5 bolts to mount everything up (need at least 1.5" long ones), but otherwise the install was a snap. They included a template for the hole locations, so it didn't take long at all to get it all mounted.

What exhaust you planning to run? I bet that EME would be right up there with the DA with smooth pipes. A pair of the pipes could be cost prohibitive though. Small canister x2 (better pricing x2) would be nice as well. These nice exhaust systems and headers are getting to be just as much as the engine!

 

[toysforbigboys]

EME is a good deal for the money! Enjoy it as much as I do my DA's.



Black oracover (ultracoat) is the issue at hand. My EF 104 and Pilot Edge both had peeling issues. Your 55m looks NICE. Looking for a home for a DA 70 and have been looking at the yaks.

I can not wait to fly this plane....its going to be a long winter just for the fact that the plane is sitting in the hobby room and it is too cold to fly.

from the looks of Ryan_m post the DA70 would fit nicely in this yak... I know that the pics done show it, but this is a huge plane for being a 50cc- 60cc plane....but the plane is super light...mine is weighing in at 15lbs 9 oz.

 

[ryan_m]

I'm just going to run the EME stock exhaust, which is just side dump mufflers.
I think the plane will have enough power with the EME70, power should be comparable to a single cylinder 60cc I think, and that ought to be plenty. If DA had announced the 2 into 1 header for the DA70 before I bought my EME I might have gone that route.

Speaking of the DA70, it has straight plugs, not angled like the EME, and I have only about 3/4" of clearance on each side. I bet the DA70 would be rubbing on the cowl on both sides. But the relief hole would be fairly small on it. The DA is good bit lighter than the EME according to the specs though, about 300 grams. Not sure how/where that much weight can be shaved off though. I did weigh my EME when I got in, and the weights were nearly identical to what milehighrc has posted for weights on the motor.

 

[49dimes]

I can not wait to fly this plane....its going to be a long winter just for the fact that the plane is sitting in the hobby room and it is too cold to fly.

from the looks of Ryan_m post the DA70 would fit nicely in this yak... I know that the pics done show it, but this is a huge plane for being a 50cc- 60cc plane....but the plane is super light...mine is weighing in at 15lbs 9 oz.

I'm just going to run the EME stock exhaust, which is just side dump mufflers.
I think the plane will have enough power with the EME70, power should be comparable to a single cylinder 60cc I think, and that ought to be plenty. If DA had announced the 2 into 1 header for the DA70 before I bought my EME I might have gone that route.

Speaking of the DA70, it has straight plugs, not angled like the EME, and I have only about 3/4" of clearance on each side. I bet the DA70 would be rubbing on the cowl on both sides. But the relief hole would be fairly small on it. The DA is good bit lighter than the EME according to the specs though, about 300 grams. Not sure how/where that much weight can be shaved off though. I did weigh my EME when I got in, and the weights were nearly identical to what milehighrc has posted for weights on the motor.

Thanks Guys. The weight of this airframe coming in at 16 or under and being a bigger plane is very pleasing. I also like the longer fuse moment of the 55M over the 54. I bet it will be better at learning rolling harriers. (I hope)

 

[ryan_m]

There is a really good podcast from 3dhs where they spend about 15 minutes talking about the Yak 55 and it's flying characteristics.
https://directory.libsyn.com/shows/view/id/39373#
I think it's that one. They spend a good bit of time talking about the rolling characteristics specifically, as well as the crankshafts and pop tops and yaw type moves that use rudder.

 

[ryan_m]

Bit more progress on the Yak the last few days. Choke linkage done, throttle servo mounted and connected up. Fuel tank got mounted and connected up last night. IBEC installed. Need to grab a grommet or two to secure my vent line in the cowl, figure out the battery mount place to balance it and she will be done.
Once I get the motor test fired and verified I'll mount the cowl and get a final all up weight on the plane with the EME70 installed and post that up. Should fly this weekend weather permitting.
Choke linkage was done with a bell crank and pops out the side of the plane, near the bottom. I didn't see many other easy ways of doing it, the way the choke arm mounts on the plane there wasn't any leverage to just drop it straight down in the cowl. Would have been extremely hard if not impossible to open and close it. And once the spinner is mounted it wouldn't have been accessible from the front either, so this worked out pretty well.
I've got some additional vent holes a bit further back in the fuse, don't worry.

 

[ryan_m]

Does anybody know of anybody that sells some type of motor cover plate like the one pictured here?
I would like to rotate that 90 degrees so that the air inlets would be over the twin cylinder heads, and then maybe build a baffle to direct the airflow over them better too. This is off of the 60" Extreme Flight Yak 54 thread, but the same concept applies...

 

[Greg Alderman]

Extreme Flight sells one for there 50cc yak...like $11. I bought one for my Yak and just didn't like the way it was going to look, mainly because it didn't fit well. Ended up just making my own. Thought about using Balsa strips to make it look like cooling vanes but just ended up painting it black.

 

[ryan_m]

Funny, I just saw the ExtremeFlight one yesterday, scoped out their site's replacement parts for the Yak and didn't see it listed. Thought about calling them to see about it. But then when looking closer it looks like their cowl doesn't curve in as much as the 3dhs one, and I was afraid that it wouldn't fit the cowl well at all. Which you seem to confirm as well. I'll fly it a few times and keep a close eye on the motor temps, in the winter time I'm not too worried about the motor getting hot. We will see if I need to baffle it once the warmer weather gets there though.

May just go the balsa route, wasn't sure how well it would hold up to the vibes from the motor though.

 

[ryan_m]

Took mine up for it's maiden flight today, the EME70 pulls it very very well. Running up on the ground I was surprised how strong it felt. Was cranking a Falcon 24x9 carbon at 6500 rpms on the ground on the initial run, and is up to about 6600 now. Had to open the low speed needle 1/2 turn to get it to start initially. It has so far proven tricky to get started in 40 degree temps, but I'm sure that will get better as it breaks in and I get used to it's nuances. I haven't gotten a weight on the plane yet though.
Balance worked out fine, the two 2s2600 lipo batteries are in the rear battery area, just in front of the rudder servo. Trying to balance it on the ground prior to flying had me thinking I was a bit noseheavy, but in the air it was great. Knife edge was dead on with no mixing, and using the inverted test it did a shallow dive, just like I like them. So I think the CG was probably about perfect for 3d. I may try and move it up a bit and see how it performs there though.
Does nice pop tops, knife edge spins, and harriers are really smooth, even with just the small SFG's on. I think those will be my usual configuration on the plane as I can leave those mounted and make assembly that much shorter at the field.
Overall very pleased with the plane and it's flying characteristics! Looking forward to getting lots more time on her.