Let me remind you a little about the project and technology.
I ordered a lot of rods with a diameter of 0.8 for the outer rim of the frame and a diameter of 0.5 for internal reinforcements.
Link to this shop.
Of course four years ago the price of the issue was somewhat different. Therefore, there was enough coal for several foam versions of the hall aerobatic aircraft.
For the manufacture of the model frame, a special stand was made, which allows working in three planes. Several furniture boards of the required size have been purchased. One half of the tabletop is removed while working with the vertical plane of the fuselage. The horizontal planes are pasted over with adhesive tape as a protection from glue. The outline of an airplane is drawn right on it.
The elements are connected by means of cyacrine and aramid thread.
An ultrathin film on Ali has been ordered to cover the frame.
The film is glued on glue “3M 77”.
Painted with tamiya acrylic enamel for bench models. Using foam stencils.
The result is a flight weight of 62 gram.
He took part in competitions on the plane several times. True, without much success. It flies better than me at the helm
After a short review of this model and its manufacture, I turn to the upgrades.
First of all, the servos were replaced with aileron control. Since there was not enough effort to roll over tremendous planes. As a result, the drive gears were constantly being cut off. Two servos, this is a great solution, allowing you to more accurately tune the airplane.
NO.NO.NO ,, , The road is paved with good intentions …. and further in the text. It was not possible to find units of light weight with acceptable characteristics; I had to install one servo drive.
Obviously heavier, but also more powerful. For weight reasons, the installation of a couple of such servos was completely ruled out. I had to correct the deviations of the ailerons purely in hand-to-hand combat. Select the length of the rods and the angles of deflection of the planes.
A lightweight standard engine of 16 grams with a regulator of 6 grams was used as a power plant.
For more acceptable flight characteristics, I made several variants of gearboxes for large propellers. The first versions of the screws were made purely of foam, but they sagged with a funnel and did not give thrust. The second option is pasted over with thin fiberglass on epoxy. Conducted experiments with balsa propeller blades. Very good results, but harder.
This allowed to reduce the speed on descending figures … The large diameter screw acted as a brake. The gearboxes use small revolving motors that transmit torque to the propeller using gears. An opening spring is provided to protect against damage. At the moment of impact, the shaft in the propeller moves back and opens the clutch of the gears of the reducer. The spring then returns the connection.
A small video of gearbox test runs and a selection of screws.
The model flew very well with the gearbox. But the small interference gears mounted on the engine shaft were constantly failing. I didn't want to participate in competitions with an unreliable system. Metal gears with the correct tooth pitch could not be found.
The standard engine was returned to the wrong place.
Wrestling comrade Victor made a wonderful coaxial system and offered to upgrade my old man. The co-axle was driven on a stand made by him. The thrust on 2S batteries is 130 grams.
Victor made a matrix for carbon propellers, I helped to finalize it.
Video of a test run of the propeller-engine group.
To install a new motor, I had to shred the nose structure of the already “tired” veteran a little.
Fitted a new motor mount from a 1 mm coal bar to size. I pasted everything on cyacrine and tied all the connections with aramid thread. When installing the motor mount, I broke the ultra-thin film in several places. But I really wanted to fly, so I temporarily sealed the holes with black tape. After that I will overhaul it. Added some reinforcing stretch marks.
The motor was inserted, it turned out to be somewhat heavier than the first option. I installed additional battery mounts, which allowed to move in search of the center of gravity.
Finally test flights.
The model flies in a completely different way. After test flights, the center of gravity was found. I'm starting to learn to fly in a new way.
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