Magic Hand RC 73" Yak build thread

[maineflyer]

I am going to start a build thread on this plane. Hopefully it will be enlightning to the quality and build of the kit as well as how it flies. Hopefully it will be helpful.
below is a link to the kit at TBM. Sale price is $229.00 and $39.00 shipping.
http://www.troybuiltmodels.com/MHYAK.htm

I have a few pictures of the plane and the weights for the set up I will be using. The website shows this plane coming in at 10 lbs. I was hoping for 10-10.5 lbs but that may be a tad optimistic.

The plane comes double boxed in a very rigid outer box. The build quality appears exceptional. The surfaces are all double beveled, cowl has a ring for a hidden mount from inside the fuse. The glass and paint on the cowl are flawless and have great detail. It rivals any glass work I have seen on a model plane. It comes protected with tissue paper and bubble wrap. The plane comes pre-plumbed and the connections zip-tied along with a fuel dot. (smaller than needed and will be changed in future offerings per TBM, it will be changed along with the fuel line as it looks narrow). The canopy is very nice and again came double wrapped in tissue paper and bubble wrap. All covering was excellent quality. Hinges are CA type and are preinstalled in the wings. Tail surfaces are installed in the flying surfaces. The horizontal stab is one piece. My plane didn't come with instructions but they can be downloaded from the TBM site. The hardware included is average quality. I have an EF Yak NIB and the hardware is much better with the EF yak. I will probably be changing out some of the hardware for 4-40 dubro stuff.

The setup will be as follows:
OS 1.60 with Slimline Pitts muffler
Hitec 5925s on Ailerons and Elevator
Hitec 5985 on rudder
Hitec 225mg on throttle
6 vt Nicad battery

Here are the weights I have for the plane and the setup: I used a digital postal scale for the below weights.

Right Wing 15.7 oz
Left Wing 15.7 oz
Hor Stab 6.5 oz
Rudder 3.5 oz
Fuse 39.0 oz
Cowl 7.1 oz
Gear 6.2 oz
Wing tube 9.0 oz
Hardware 8.6 oz

Engine 38.0 oz
Muffler 5.8 oz
Prop (APC) 4.8 oz
Spinner 2.1 oz

Servos 12.0 oz
MPI arms 1.0 oz
Extentions 3.0 oz (est.)
Battery 8.0 oz (est.)
receiver 1.0 oz
switch 2.0 oz
Misc 4.0 oz (est.) Spats 1.6 oz (optional)
_________________

193 oz total all up weight
12.06 lbs

Wing Loading 27.59 oz/sq'

Magic Hand RC site data:

Length:1690mm (66.5in)
Wingspan:1850mm (73 in)
Wing area:65dm2 (1007 sq in)
Engine: 4C 120~160
Gas Engine 26-30cc
Weight:4.2-4.5kg (9.1-10lb)
Radio:4ch-6ch

(There is a slight discrepancy with TBM site on wing area 977 sq inches)



I will be starting the build in the next few days.
Here are a few pics of the plane as I was weighing it

Jeff

[thewrap]

Nice. 11lbs not bat. I think my Wild Hare is close to the same size and weighs close to the same.

[mikeh]

Sharp looking plane. I like that scheme better than the other one.
Mike

[maineflyer]

I would like to get it a little lower. I am still undecided on the battery. I like the simplicity of nicads and want a low impudence so I am looking at these options from NoBS.

Sanyo CP-1700SCR Nicad 5 Cell Rx Pack
Cell Size: 4/5 Sub-C
Type: High Rate Nicad
Dimensions: .9 x 1.33
Cell Weight: 1.6oz
Impedance: 5.5 mOhms

Sanyo N-1900SCR Nicad 5 Cell Rx Pack
Cell Size: Full Sub-C
Type: High Rate Nicad
Dimensions: .9 x 1.69
Cell Weight: 1.9oz
Impedance: 4 mOhms


If anyone has any onther battery solutions I would love some imput. I am new to digital servos and am concerned with low voltage situations with my AR-7000 receiver

[ericb]

Almost 2lbs over the top weight on their site with a little less wing area. Where did they get their numbers?

[maineflyer]

I don't know about the weight. Either my digital postal scale is off or things are a hell of a lot lighter in China. I've built a lot of models and never had one come in less than the high end of the weight range with out major rehab. I think they find the most pollyanna person in the shop and tell him to do the weighing and oh by the way round everything down to the nearest ounce....

[maineflyer]

Wings:
I looked at the hardware again today and changed it out to dubro ball links and connectors as well as 4-40 threaded rod for the push rods. The included rods were 2-56 and had metal connectors and 90 degree keepers which I don't use on anything bigger than 40 size planes.
Here is a picture of the hardware, the four bolts are wing attachement bolts.

[maineflyer]

I then did the normal mounting of the servo and arm. The instructions are spartan at best although anyone who has ever built a plane or assembled an ARF shouldn't have any issues. I am using MPI 1 1/4" arms for this plane.

[maineflyer]

As I stated earlier there are no instructions on placement of the control horns so I winged it !! I Ran a straight edge down the side of the servo (which is 90 degrees to the hinge line) and transferred a mark on the aileron. I then moved the servo arm to the end of its travel and measured the distance from the hole on the arm to the side of the servo, once I had this distance (18mm approx) I transferred it to the aileron. The only remaining thing was finding out how far into the aileron to drill the hole and this was easily found by putting the control horn over the hinge line so that the hole in the arm is directly over the hinge line and marking the point where the control arm should go through the aileron. I made my mark and drilled though the hardwood bock. Once through I always put some thin CA in the hole to harden it more and then mounted the control rod.
What this does is give you great mechanical advantage when your surface is fully deflected. The pushrod is 90 degrees to the flying surface.

[maineflyer]

I also like to do a little sumtin-sumtin extra with the linkages. I lower the push rod linkage so that it is exactly the same height as the servo arm when the surface is fully deflected. The way the control rod is exactly parallel with the servo arm. Once again providing every little bit of mechanical advantage from the servo.

[maineflyer]

The finished product: Now do the other wing

[rcairflr]

For the wing-area, you could measure it and get a comparison to the advertised, sometimes this is also exaggerated.