2020-2021 Buildclass model suggestion; build and discussion

Michael · February 26, 2020, 11:19:31 AM

Red Monokote film and blue Monokote (sticky-back) trim.

A few coats of water based polyurethane to seal the wood, sanded in between, on the motor pylon and tip-floats.

Parts readied for spray painting.

davidk · February 26, 2020, 11:59:13 AM

Nice trick with the pliers to hold stuff. What are the pins for in the tail?

Michael · February 26, 2020, 03:02:43 PM

Quote from: davidk on February 26, 2020, 11:59:13 AM
Nice trick with the pliers to hold stuff. What are the pins for in the tail?

Just to hold stuff in place. Not glued yet.

Michael · February 27, 2020, 08:59:16 PM

Tail decoration and then glued in place.

Before hinging the rudder, I noticed the rudder ran below (lower, longer) the lower fin. If I had left it that way, it would have ripped off when taking off or landing on grass. I cut it shorter, and re-covered that section, as in the photo with the blue arrow.

Elevator and rudder servos, pushrods, control horns, etc., installed. Working slowly, calmly and carefully, the servo installation took a couple hours.

bweaver · February 27, 2020, 11:08:55 PM

Quote from: Michael on February 27, 2020, 08:59:16 PM
Tail decoration and then glued in place.

Before hinging the rudder, I noticed the rudder ran below (lower, longer) the lower fin. If I had left it that way, it would have ripped off when taking off or landing on grass. I cut it shorter, and re-covered that section, as in the photo with the blue arrow.

Elevator and rudder servos, pushrods, control horns, etc., installed. Working slowly, calmly and carefully, the servo installation took a couple hours.

Good thing to make the changes for float flying too. It likely would have got hung up on the weeds too. Looking Great!.

Can't wait to see more of Vadim's construction as well.

Michael · February 28, 2020, 12:10:00 PM

Servo prepared for installation exactly as per instructions. I had my transmitter, receiver and wiring ready, and tested everything each strep of the way.

Servo installed.

I found an error on the plans. The plans show the holes in the elevator control horn lining up ahead of the hinge/pivot point (red line in photo). It should be right on the hinge/pivot line (blue).

Aileron linkage installed and complete, using wire, Dubro Micro EZ links (plastic clips, as per instructions). The "V" shape in the wire is to allow for adjustments.

Michael · February 28, 2020, 12:12:35 PM

Motor pylon and tip-floats painted and waterproofed.

Tip floats glued in place.

Motor pylon rear cowling cut to shape and glued on. Cut oversize, and then fit, cut, fit, sand, fit, etc., until a snug fit.

Michael · February 28, 2020, 02:14:15 PM

Motor mounted on the pylon.

Note that the motor I'm using has a Kv rating of 1400.

*********

What is the Kv rating of an electric motor? Answer: "Kv" refers to the constant velocity of a motor (not to be confused with "kV," the abbreviation for kilovolt). It is measured by the number of revolutions per minute (rpm) that a motor turns when 1V (one volt) is applied with no load attached to that motor.

*********

The higher the Kv rating (all other things being equal), the smaller the propeller size; the lower the Kv rating (all other things being equal), the bigger the propeller size. Because this model requires a relatively smaller propeller, I would recommend builders acquire a motor with a Kv rating of no less than 1200. Otherwise, a motor with a lower Kv rating won't spin the small propeller fast enough to fly the plane.

I'm also using a 30 amp speed control, probably more than double the rating that's required to fly the plane, but by using a higher rated speed control, it will not get too warm/hot inside the fuselage. Be aware that there will be no airflow over the speed control to keep it cool.

Michael · February 28, 2020, 03:25:23 PM

The front cowling was supposed to be glued over the rear cowl, but it didn't fit. I guess I glued the halves together a bit too closely.

It did however fit nicely over the plywood spacer I used to mount the motor in the right position, so I trimmed it and screwed it to the spacer. It looks decent.

I then glued the assembly to the top wing center.

Michael · February 28, 2020, 03:32:11 PM

The 'build' is complete.

I still have to look over the model carefully in case there are any exposed wood areas, or places where water could seep in. I'll make it as waterproof as possible.

I also have to prepare and install the rest of the radio and power system (receiver, wires, speed control) and the battery to balance as per the plans. I also will adjust the throws (elevator, rudder and aileron deflection) as per the plans.

I think I did a good/OK job on the build and covering, but considering I built it quickly, and the main intent was to have fun, I'd give myself an 8/10 or slightly better on the finished product.

It was not too hard to build, but I wouldn't recommend it as a fisrt time 'build' if the modeller was building alone. With the support of other TEMAC members, I'm sure just about everyone could produce a good flying model from this kit.

bweaver · February 28, 2020, 03:51:57 PM

davidk · February 28, 2020, 03:56:36 PM

Agreeing with Bruce... I don't see where you lose 2 marks. This is a 10. The front cowling fits, and looks, perfect. I might agree with your comment about a first time build... if... your very detailed build process was not available. But... it is... and so this will be my first build because it will fly off land and water. I'd already planned a red and white scheme but opposite to yours with red being the main colour.

It's beautiful, Michael... nicely done.

Michael · February 28, 2020, 06:25:02 PM

Thanks guys.

The plane weighs about 618 grams with battery, which is almost 22 ounces, 5 heavier than advertised. I used a 3-cell 1800 mah battery to balance the model without using extra weights, about 50% over the 1250 mah battery they recommend.

It still 'feels' very light.

I really like the handling of this plane with the power on. I taxied it a bit on the carpet in my basement. Because the propeller is mounted high, the prop-blast goes directly to the fin/rudder, and direction control on the ground is excellent.

VadimKirillov · March 01, 2020, 12:34:19 PM

The work has started it is very easy to build, just follow the manual. It's a great project to practice for CA glue. I'm using thin CA for most parts, very fast and easy just have to fit parts very well before glueing.

VadimKirillov · March 01, 2020, 02:05:42 PM

The one difficult thing I ran into first, I think it deserves a special post, is pressing in blind nuts. While pressing the nuts I have cracked the plywood. So I have traced it on scrap peace of ply that was left. And drilled net pilot holes in ply and wood plank underneath. Then I enlarged holes on wood plank so that nuts can easily go through. I placed ply flat on wood plank for better support and hammered the nuts. No cracks ply is strong and with a bit of CA glue it will hold the wing solid.