bob_nj

My Feedback: (62)

I came across a thread from 2005 on the Aviation Models 35% Yak build.
Is the SD relatively the same as the one in the build thread?

My question is about the hardware supplied in the ARF you can buy today?
Is the hardware in the ARF useable?

What is the overall impression of the plane that is available today?
Any differences than the one from two years ago?

I have a big Cap, Extra, and Edge and am thinking about the Yak.
Just want to do some leisurely freestyle type flying.


Thanks
Bob

DMcQuinn

My Feedback: (13)

I purchased a 35% SD-Models YAK from Chief aircraft in oregon about 6 weeks ago. I am very happy with it overall. I used all the hardware, except for the engine mounting bolts. It came with aluminum landing gear. I have about 30 landings and the gear is still straight. The wheels are already showing some signs of wear. (I think the wheels came with the ARF - but perhaps I just had these from a previous plane). The control horns are typical steel bolts (#10 size I think). All of the bolts are imperial/SAE (not metric) as I recall. I weighed every part on a gram scale before I assembled the ARF. It comes out about 30 pounds with a DA -100. I don't think it came with a tail wheel assembly.



Item Ounces
Fuselage 70.0
Canopy 9.5
Hatch Cover 9.0
Rudder 7.8
Wing and Aileron (L) 39.9
Wing and Aileron (R) 40.5
Wheel pants (2) 4.6
Aluminum Landing gear 18.4
Main wing tube 14.9
Stab tube 2.4
Stab & Elevator (L & R) 15.1
Spinner 7.4
Prop (wood Xoar 27x10) 7.4
Hardware pack 14.9
Tank (w/ clunk) 5.6
Tygon tubing 1.0
Wheels (2) 5.5
DA 100 w/ mufflers 106.0
Prop bolts (6) 1.2
motor bolts and standoffs 4.3
Cowl 17.6
DA ignition 6.4
Firewall 6.4
Motorbox cover 2.0
TX Batt 5 cell 2250) (2) 12.9
Ign Battery (4 cell 1200) 3.4
receiver (10 ch PCM) 2.4
Switches (3) 2.4
Servo - DS 8411 (6) 12.0
Servo - Hitec 5955TG (3) 6.6
Servo DS 821 (choke) 1.9
Telemetry recorder 1.2
Telemetry transmitter 0.5
Servo Extension wires 2.3
Tail wheel assembly 2.5
Glue 3.0
No Pilot 0.0
468.9

bob_nj

My Feedback: (62)

Thanks for the detailed response!

If you've flown it, what is your impression so far?
Did you need stand offs with the DA 100?
What mufflers work with the Yak and DA?

I may be pestering you with questions now

DMcQuinn

My Feedback: (13)

I've got about 30 flights and I'm quite happy with the performance. Nice mix of precision and 3d capabilities. It does point rolls better than any plane I've flown. My previous plane was a 35% matt chapman cap and the one before that was a 35% carden cap. So I can't compare the YAK to Edges, Sukhois, Extras, etc. My previous caps would harrier and waterfall better than the Yak. The yak is 30 pounds versus the Cap's which were 27 pounds. The Yak also has more wing area (2200 sq inches). Basically the SD-Yak is a bigger plane than most 35% planes.

The firewall comes unassembled, so you must deermine where to position it. I measured up my DA-100 and calculated where to glue the firewall. I was targeting to get about 1/2 inch of space and planned on using a 1/2 inch spacer to get the engine just right against the cowl. But I ended up with no spacer at all. I think I cut off the motor box sides about 1/2 inch and then glued the firewall flush with the ends of the motorbox sides. If I was to do this again, I would cut them a little shorter and then use spacers. I like to have about 1/2 inch spacers between the firewall and motor. It gives some breathing room for cooling air and also gives some room for the mufflers. I am using "stock" DA mufflers. The plane is set up for cannisters if you prefer that.

I spent quite a bit of time to fabricate baffles inside the round cowl to force the incoming air through the cylinders. The instructions do not always match the reality of the kit as they have probably re-engineered some things. Don;t hesitate to ask more questions. One thing I remember is that the instructions call for attaching the horizontal stabs with a screw from the bottom into the aluminum tube (these are removable). But the ARF clearly has an attachment method using 2 screws from the root rib into the fuselage and the screw into the aluminum tube is no longer used. So basically, you can ignore some of the instruction manual.

I think I need a little upthrust. If I trim the plane to fly level at full throttle, when I pull back the throttle to idle the plane slowly pitches up as it slows down. I have it pretty tail-heavy also.

With the DA-100, mine was a little nose-heavy. I originally put the batteries near the CG and have since moved them back about 18 inches. I'm running a wood prop and the aluminum spinner that came with the ARF.

cliff600

My Feedback: (3)

I really like mine alot too. I agree with just about everything DMcQuinn said. I used 3/4 inch standoffs instead of trimming the firewall box. I would recommend getting a new set of landing gear TNT or Carbon Fiber. You probably will not need it right away but It will be good to have on hand so you won't need to wait for them to come in. I used a DA 100 also and I did baffel mine too, but a good friend has one also and he did not baffel his at all and has not had any problems. I put my batteries right behind the wing tube and used a tru turn spinner with a lite backplate. I used the hardware with the plane but I did not use the servo horns they supplied, I used 1 inch aluminum arms on the ailerons and 1 1/2 alum arms on elevator. For the rudder I used a SWB servo tray. This has been the nicest flying, easiest landing plane I have ever flown. I have a smoke system in mine too, it came out just a tad nose heavy, but it has not affected the way I fly it. Read the first post, just about nothing has changed as far as the instructions go.

bob_nj

My Feedback: (62)

Thanks again for the info.
I'm kicking around the idea of this being my next project.
I like the more "in front of me" kind of flying, and this may be a good choice for that.

So 30 pounds isn't out of whack as a weight huh?

DMcQuinn

My Feedback: (13)

Well I'd rather it was 27 pounds, but I could not figure out how to make that happen. I have replaced the aluminum wing tube with Carbon Fiber wing tube (saved a few ounces). The landing gear is another likely candidate, then the spinner. The wheel pants are currently off (one fell off in the weeds and I can't find it). So it is lighter today than when new.

I can't tell the difference. I've read about people using the BME 115 for power. This may be a good combination if you like the BME. Even at 30 pounds, it flies and 3d's fine. The waterfalls are bad. I don't know if it is the power-to-weight ratio or what. It is plenty tail heavy and I have 45 degrees of elevator travel. The waterfalls are just slow and difficult to maintain a heading.

bob_nj

My Feedback: (62)

DM, if you had to do it all over again, is there another choice you would make for a 100cc plane to do the kind of flying you like?

Bob

DMcQuinn

My Feedback: (13)

I'm pretty happy with the Yak. I think I'll continue to get better with it. I flew Cap's for 6 years so I was getting pretty comfortable with them. I think eventually I'll appreciate the Yak even more. The first 15 flights or so I was pretty nose heavy and the trimming was not right. I'm getting it dialed in still. When it is all trimmed up perfectly, maybe even the waterfalls will get better. You may want to ask someone that has flown a wider variety of SA planes (edges, extras, etc.). I've only got a couple of flights on a borrowed Edge and since it was not mine, I was not comfortable with it.