Looking at this unusual aredigital, could not help thinking that he was inspired by the famous Swedish writer Astrid Lindgren for creating well-known children’s story “Karlson on the roof”. The kids loved the kid Carlson, and not the last role in this played the “technical equipment” lover of raspberry jam — it is famous for the motor with the button on his belly…
The journal “modelist-Konstruktor” more than once wrote about the work of student design Bureau Mari Polytechnic Institute named after M. Gorky (SKB MPI). One of them is backpack aredigital especially interested readers. Today we published a detailed description.
The first prototype of this device, which received index MPI-4, was designed and built in 1967. MPI-4 was designed on the basis of the motor chainsaw “Friendship” with a capacity of 5 HP (diameter of the propeller is equal to 700 mm). The expert Commission of the USSR recognized it as one of the best student work and recommended for wide implementation in the national economy to provide such apparatus geologists, Rangers leskray, that is, those who are on duty have winter to overcome in off-road conditions long distances.
Recently on NTTM-78 exhibited the latest development of SDB MPI (head S. F. Kirkin) — upgraded backpack aredigital MPI-5. The basis for it was the more powerful engine chainsaw “Ural”, and mount the propeller unit to the back of the skier is much easier than in the first embodiment.
Fig. 1. Knapsack aredigital MPI-4:
1 — the handle and the rope starter, 2 — ring, 3 — propeller, 4 — pen and the control arm, 5 — exhaust pipe, 6 — horizontal arc ring 7 — hose clamp exhaust, 8 — lug, 9 — damper, 10 — turnbuckle, 11 spacer, 12 — base plate, 13, 14 — shoulder straps, 15 — fuel tap 16 — tank 17 — neck tank, 18 — clamp tank, 19 — gas line, 20 — candle 21—engine 22 — carburetor, 23 — flange coupling, 24 — flange 25 — bolt with nut, 26 — vertical arc ring 27 — bolt with nut, 28 — a protective grid.
Fig. 2. A structural diagram of a knapsack aredigital MPI-5:
1 is a vertical arc ring, 2 — sides ring 3 — horizontal arc ring, 4 — bracket lap belt, 5 — waist belt, 6 — support plate 7 — spacer, 8 upper strap 9 shoulder bracket, 10 — padded shoulder arc, 11 — left shoulder arc, 12 — starter handle, 13 — right shoulder arc, 14 — wire, 15 — pulley rope starter, 16 — tank, 17 — gas line, 18 — high voltage wire, 19 — propeller, 20 — ring fencing of the screw 21 is the engine of the chainsaw “Ural”, 22 — carburetor, 23 — flange mounting screws, 24 — propeller spinner, 25 — protective mesh, 26 — handle engine control, 27 — the “stop”button.
Structurally, aredigital (as MPI-4 and MPI-5) is simple. We should not only forget that the unit is located on the back of a man; therefore, every detail of the installation should be carefully designed taking into account its weight — certainly not at the expense of reliability and durability.
As already mentioned, in aerodigestive MPI-4 used engine from a chainsaw “Friendship”. It is lightweight, compact and at the same time powerful enough. Attached, like all other parts and components to cut from plywood 10 mm thick base plate. You can use other sheet materials — PCB, made of anodized aluminum, vinyl. The last two are preferable, as they allow you to bend the plate in the form of the back. Surface, it is desirable to paste over with foam rubber in the thickness of 20-30 mm is vibration.
To mount the device on the shoulder straps (MPI-4) at either shoulder arcs and belts (MPI-5). The latter option is better, as arc transfer the load more evenly than the straps, and also prevent accidental displacement of the structure.
The motor is fixed on the base plate via the spacer, bent from sheet aluminum, screw-on couplers.
For installation of the propeller serves as an intermediate flange coupling. Its sleeve it is mounted on the shank of the crankshaft, the propeller is mounted with M6 bolts directly to the flange of the intermediate clutch.
Propeller CCW rotation, cut from the dry birch of the bar and carefully balanced. After processing, are covered with cloth and covered with several layers of nitroenamels.
The protective ring is aluminum pipe with riveted thereto a metal tape with a width of 70 mm connected with base plate vertical and horizontal arcs. The fence is covered with a red or orange nitroenamels. The lower part to a horizontal arc — snug coarse metal mesh.
Fuel is supplied to the carburetor of the engine by gravity from a tank located on the upper branch of the vertical arc. To reduce the emitted engine noise in the exhaust system includes the muffler.
Engine management is a flexible cable in budenovskoy shell connecting the throttle valve of the carburetor with the handle, which aerolight holds in her right hand. The handle has only one lever — the Gaza strip. In the end there is a stop button an emergency stop of the engine, which closes to ground the primary winding of a magneto. Use it should be in the fall, or other unforeseen circumstances. In aerodigestive MPI-4 this button is located on the left shoulder strap.
Fig. 3. Air screw aredigital under the engine from a chainsaw “Friendship”.
side view and rear.
Engine starting — starter Shnurov. In MPI-4 length of cable is enough to run leg, and in ISSS-5, the starter handle is located on the right shoulder of the arc and the engine starts hand. In the final model, the rope automatically returns to its original position.
A few words about security measures and methods of training to slide on skis with “motoryzacja” behind.
To start the engine should only crank. In any case, do not resort to promotion of the propeller! It is not recommended to move aerothe a large gathering of people.
When driving try to stay directly below the plane of rotation of the propeller is perpendicular to the ground — in this case the propeller thrust is fully utilized and is no additional resistance to movement. Avoid sudden turns of the body. When loss of balance is necessary, not waiting for the fall, first click on the “stop” button and stop the engine. Fall (if such a thing happens to you) forward, on the chest or on the side. Avoid falling on your back is dangerous!
When you master aredigital and will be able to follow all these simple rules, you will get great pleasure from rapid slip on my own two feet at speeds up to 50 km/h.
I. USENALIEV, engineer