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Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 26 Nov 2019, 05:41
by norm
FWD Fuselage
As many guests have interest in my model's fuselage construction, I will post its details in order. This time topic is the FWD fuselage.

Mita's FWD fuselage is made by several truss panels. These panels are flat but they are assembled with angles each other.
So, an assembling jig is required. I made the jig using wood bars and plates. This jig is also useful to construct the landing gear support structure and to joint the FWD and AFT fuselages. Be careful that attached photos show the structure before epoxy glueing.

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 26 Nov 2019, 09:35
by VinceC
Incredible research and attention to detail. Excellent work

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 26 Nov 2019, 19:43
by Jolly Roger
You have made some very beautiful and elegant structures. I can imagine the fuselage must feel very light and stiff.

If the joints between carbon tubes are strong enough to take the model flying and landing loads, I think many people will be interested in trying this method. Carbon tube can be bought cheaply on eBay and from HobbyKing.

I would like to hear more about how you glue and reinforce each join, for example, do you make your own carbon powder? And do you insert any material inside the tubes at the joint?

Thank you again.

Roger

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 27 Nov 2019, 05:20
by norm
VinceC and Jolly Roger, Thank you for your comments.

Jolly, I used the carbon powder available from retailer and mixed it with epoxy glue. Although it is named "powder", it contains small carbon fibers and if you mix it with epoxy glue it becomes CFRP. It is very tough and light. Weight of the completed basic fuselage I posted yesterday is only 710g nevertheless its length is over 2m. It is very rigid too.

Carbon pipes are jointed with a short piano wire inserted and glued by epoxy where possible, but most joints are just epoxy bonded only. Those joints that seem to be important are bonded with a small carbon plate for reinforcement. The wing support beams are tied up with the longerones by carbon threads and glued. Please see attatched pictures.

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 27 Nov 2019, 12:00
by norm
Tail Wing Mounting brackets, Tail Skid and the Elevator Bell crank
The horizontal stabilizer is mounted with three M3 bolts through carbon pipes placed on the AFT fuselage. The vertical stabilizer is mounted at the end of the fuselage with two M3 bolts.

The real Mita's tail skid is made of three ply of steel plates with an abrasive shoe. In my model it is made of carbon plates with an alminum shoe. These plates are not bonded each other for the maximum spring effect.

A bell crank made of carbon plate/pipe is equipped under the horizontal stabilizer which is connected with the elevator.

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 27 Nov 2019, 12:31
by Peter Balcombe
Norm,
How did you cut the bellcrank plates?
Are they all made by hand, or do you have CNC cutting facilities?
Very good work anyway :)

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 27 Nov 2019, 12:54
by norm
Peter, I cut them by hand with a mini router which has a diamond saw. Then they were trimmed by a diamond file.

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 28 Nov 2019, 02:34
by norm
Fuselage sub structures
The Mita's fuselage has sub structures around its rectangular main structure, the lower sub-structure, the upper sub-structure and the side beams. With these sub structures its cross section forms octagon when coverd with fabric. Both the upper and lower sub-structures are made of carbon pipes and the side beams are made of paulownia plates.

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 29 Nov 2019, 06:59
by norm
Motor mount
This time I will show you the motor mount.

Why Motor? This may be a common question of the European scale glider fans. First of all I must explain the Japanese scale soaring enviroment. Japan consists of innumerable islands, lage and small, of which four islands are relatively large and most people live there. Total area of Japan is about 370 thosands square km. It is a little bit larger than Germany but, in contrast to Germany, its 70% area is mountainous and 2/3 are covered with forests. On these islads there live more than 120 million people. So there remain little spaces for model glider flying. Because of these enviroments, it is not common to use a tag or a winch that requires somehow a large space. It is common to install a motor and a foldable prop. By the way, because of limitted space, 1/5 scale models are called big and 1/3 scales are extra-big in Japan.

The motor mount of my model extends forward from the main fuselage and requires a special jig to build it correctly. The motor is mounted on a plate made of 9 mm thickness plywood. This plate is supported by carbon pipes and plates. A plywood plate is bonded on the upper side on which the ESC and a battery for the receiver will be installed later. The motor is FUTABA FMA-5065 KV300, 2000W class motor.

Re: 1/3 scale Japanese vintage glider Mita type 3

Posted: 30 Nov 2019, 06:18
by norm
Tow Release
There are two tow release equipments in the original Mita, for the aerotow and for the winchtow. The former is at nose and the latter is in front of the landing gear. I have no tag nor winch but I made these equipments for the model. They are not dummy but really work. These are hand made with aluminum plate. One servo actuates both. As the elevator control tubes pass through the center of fuselage, the winch tow release is attached on the port.