FLYING THE “FUNNEL” | MODEL CONSTRUCTION

In one of the reports of competitions rocketmodeler I noted an unusual model sports class Ѕ6А famous athlete Nikolay Sergeeva from Belgorod. How many know it, and you know we have more than 30 years, never ceases to amaze his creative imagination. Was no competition, so he brought them his “brand” new. So it was this time.

Sometimes ask myself a rhetorical question: “What can I propose a new class of models with tape (Ѕ6А)?” And like Sergeev says: “you Can!” Indeed, provided the original design, where the braking device reduces the speed of descent of the model that is used not only tape, but the case made the drop-down. This innovation allows several times to increase the area of the braking surfaces of the model. In the expanded form (descent mode) it is similar to a funnel or cone with an upper diameter of about 500 mm.

I must admit that model-“folding beds” for the first time I saw in the distant 1979 and 1981 in the European Championships. The authors were josé Ignoto (Spain) and Anton Repa (Czechoslovakia). Case in the models decomposed in only two folds, and the additional braking surface was quite small and not always effective, although the structure was complex. Apparently, therefore, this scheme is not widespread.

Funnel N. Sergeeva on the part of the braking surface is far superior to the previous one. But she has some “weaknesses” – high technology manufacturing, insufficient testing of the disclosure of the case and, finally, a large flight weight – about 10.5 g (without tape and MRD). But in any case the scheme and design of the aircraft gives excellent food for thought to rakatomalala-experimenters.

The descending part of the model rocket with open brake “funnel”

Structurally, the model N. Sergeeva consists of a head fairing, hull and tail unit, and in appearance no different from the usual sports missiles S6A.

Before its construction, it is necessary to prepare the mandrel. Is three: for the head fairing, tail unit and the housing. For the latest suitable mandrel to conventional models S3A and S6A.

Fairing is made of fiberglass, in that order. The mandrel is slightly warmed and smeared with mastic separation “Edelvays”. From fiberglass with a thickness of 0.03 mm on a pattern to cut the workpiece into two layers. Spread it on a flat, smooth surface and lubricated with epoxy resin. For the best impregnation of fiberglass can be heated oiled billet ordinary hair dryer. Then, holding the mandrel in the Chuck of the lathe or in the vise, wrap the fiberglass around the mandrel, and the top to tie the thread, eliminating the possibility of deployment.

After zatverdzhennia binder treated outer surface of the obtained fairing and butt length to the desired size – 110 mm. At a distance of 12 mm from the lower edge glued to the balsa frame thick 1.2 – 1.5 mm. Then inside the fairing to the frame are glued ring made of fiberglass with a diameter of 35 mm and a length of 25 mm. To the inner surface, attach a strong thread cut length 250 – 300 mm for connection with the main body and the brake band.

Model missiles Ѕ6А N. Sergeeva:

1 – fairing; 2 – frame; 3 – supporting ring; 4 – external fold; 5 – inner flap; 6 – thread suspension brake band; 7 – brake band; 8 – wad; 9 – tail unit; 10 – stabilizer; 11 – retainer MRD

The same technology vyklevyvajut and tail block. Only the location of the transition cone into the cylindrical part of the additional reinforcing layer of fiberglass. After sanding the surface of the workpiece is cut to a length of 185 mm and fasten the stabilizers. Them three, they are cut from the balsa plate thickness of 0.9 mm, the lateral surface of the reinforced epoxy resin. In the place of fastening of one of the stabilizer glue the latch – retainer MRD, bent from a steel wire in diameter of 0,8 mm.

The body of the model consists of two layers of flaps – internal and external.

Each layer includes four sash, pivotally hung to the tail block (the cylindrical part). The sash is made from balsa veneer thickness 0,8 – 0,9 mm on a conventional mandrel with a diameter of 39.5 mm. the Plate of pre-steamed veneer is applied to the mandrel and wrapped a rubber tourniquet. After drying, fold cover nitrocellulose lacquer for retaining a predetermined concavity. Next, cut them to the desired length, moonlighting at the side, making them fit to each other tight, and also cover nitrovarnish. It must be borne in mind that the sash for the outer layer should be 5 mm long and 3 to 4 mm wider than for domestic ones.

Mount the valves to the tail block on the hinges from strips of nylon with a width of 6 mm. First, glue the inner leaf. On the outer surface of the fixed gum for their disclosure. One end of the elastic to the point of strengthening the tail unit, the other to the sash at a distance of 40 mm from the bottom edge.

To limit the angle of opening of the valves (75° from the vertical axis of the model) on the inner side of the blade is fixed to the thread-limiter made of Kevlar. Its other end is attached to the upper edge of the caudal block. It is the glue and thread suspension brake belt length 800 mm. in the same way and hung external doors. They do not have elastic opening and are deflected by the interior, but the thread-limiter attached to them.

And yet, external doors are fitted circumferentially offset by 45° relative to the inner so that their joints do not mix – due to possible occurrence of turbulence and destruction of missiles in flight.

Mandrel for production of a model class Ѕ6А:

a – fairing; – tail block

In the expanded form model, its body, similar to a funnel or cone with an internal angle of 150°. To increase the area of braking by a larger opening angle of the valves should not be. This taper provides a stable position of the model during the descent.

The model is equipped with a brake tape dimensions 150×1550 mm, film thickness of 0.03 mm.

Preparing the rocket for launch produce in such sequence. Connect the thread of the fairing with the tail section and tied it to the brake band. In the tail section of MRD is inserted, locking it with a latch from accidental shooting, and close the top with a wad of foam. Then fold the inner fold, forming a cylinder, the free end of which wear (10 mm) fairing, or rather its retaining ring, after having put inside the brake band. Then fold in the cylinder outer folds, pressing them to the inside, and to stop wear on the top fairing, which captures them from disclosure. The model is ready to start.

In flight, at an altitude of 180 – 190 m works lifting charge MRD, which “shoots” fairing, releasing the sash of the case. They’re under the effects of the gum are disclosed, forming a kind of funnel. At the same time reveals brake band and model lands.

V. ROZHKOV

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