Acrylic products

Acrylic or organic glass has been used in aviation for almost a hundred years. The invention of this material occurred during the period between the two world wars. The unique characteristics of acrylic have become the reason for its increased demand in the field of military and civil aviation. The new material for the cockpit windshield had optical transparency, shatterproofness, and water resistance. In the post-war years, flight speeds and altitudes grew indomitably, and the industry developed at a rapid pace.

At the same time, acrylic glass manufacturing technologies were developing, and the properties of this material were striving for perfection. Increased demand for plexiglass in aviation is also observed in our time - acrylic is the only material that can withstand the most difficult operating conditions in the air. Today, only acrylic aviation plexiglass is used for glazing cockpits of combat and civil aircraft and helicopters.

Windshields for airplanes and helicopters: glazing of combat aircraft

Acrylic acts as a powerful force link along with the metal elements of the body structure. The safety of the crew and the success of combat operations depend on the reliability of the windshield of an airplane or helicopter, so we take full responsibility for the quality of our products.

- Highest impact strength. Strength is determined based on the most difficult operating conditions during combat operations. Acrylic glass for aviation withstands not only bird strikes, but also vibration loads associated with extreme maneuvering of the machine. The use of acrylic with bullet-resistant properties protects the combat vehicle from fragments in the most critical moments of the battle.

Civil aviation: custom windshields for airplanes and helicopters

Acrylic glazing is an excellent solution for making custom windshields for airplanes and helicopters. Acrylic allows you to create elite-class models, unique in their design. Regardless of who will use the aircraft - private individuals or official representatives of states - the requirements for such structures are very high. Airplanes and helicopters of increased comfort for VIPs must ensure absolute safety of transportation and at the same time have a high-class appearance. Acrylic allows you to solve these problems easily and without extra costs.

Excellent aesthetic characteristics. Shiny and perfectly smooth acrylic glass has a high light transmittance, the transparency of the material is maintained in all weather conditions throughout its entire service life.

Any design. The technological capabilities of acrylic make it possible to create aviation products from acrylic of any configuration without minimal damage to strength and reliability.

Self-cleaning surface. The possibilities of acrylic in ensuring the ideal condition of glazing are quite wide. Thanks to a special dirt-repellent coating, the surface of the glass always remains clean and shiny, and therefore does not require intensive care.

Noise and UV protection. Special technologies make it possible to produce custom-made windshields for airplanes and helicopters with protection from the negative effects of solar radiation and noise. Staying in the cabin becomes as comfortable as possible, while natural light remains at the maximum level.

Frost and heat resistance. Acrylic glazing of aircraft is designed for operation in a wide range of temperatures - from the scorching southern heat to the burning northern frosts.

The AkrylChik company has a powerful technological potential that allows it to work with complex aircraft glazing in accordance with the stringent requirements of state and international standards.

Polishing aircraft and helicopter glazing

In order for aircraft glazing to serve for a long time and without failure, it is necessary to periodically perform polishing work. Polishing allows you to remove the smallest abrasions and scratches that could appear due to contact with birds, insects, dirt, and precipitation. Smooth polished surfaces do not retain the smallest particles of dirt, moisture, or ice. A self-cleaning effect occurs on the surface. Timely contacting our specialists for service is a guarantee of long-term operation of aircraft glazing. Regular polishing improves not only the performance, but also the aesthetic characteristics of the machine. High-quality polished glass provides an excellent overview and clearly conveys colors and shapes. Glossy surfaces emphasize the presentable appearance of the aircraft and serve as an attribute of the high status of the aircraft owner. By entrusting the glass polishing to us, you will make a profitable investment in the durability and reliability of the aircraft. Polishing work is carried out by high-class specialists. A team of craftsmen can go to a site in any city in Russia and perform a full range of turnkey polishing work on aircraft or helicopter glazing.

Aviation plexiglass

Technical characteristics of aviation plexiglass according to GOST 10667-90:

Aviation plexiglass GOST 10667-90. A wide range of organic glasses has been developed for glazing air transport. Let's consider one of the most popular options - aviation plexiglass (acrylic), which is produced in accordance with GOST 10667-90. The thickness of such glass varies from 1 to 50 mm. Dimensions of sheet blanks: 1170x1340 mm and 1500x1700 mm. Other sheet dimensions can be ordered from manufacturers upon individual request. Aviation plexiglass brands: SO-95A, SO-120A. The abbreviation CO means “organic glass”, the subsequent number is the softening temperature at which the thermal molding of plexiglass is carried out, the letter “A” indicates that the material is intended for use in aviation, namely for glazing airplanes and helicopters.

Aviation plexiglass GOST 10667-90 has excellent performance characteristics. Fire safety indicators comply with GOST 12.1.044. The material does not emit toxic substances at operating temperatures.

Technical characteristics of aviation plexiglass PLEXIGLAS GS:

Aviation plexiglass PLEXIGLAS GS. Evonik, with whom we have been cooperating for many years, also offers a line of organic glasses for aviation applications. In particular, plexiglass of the brands PLEXIGLAS GS 249, PLEXIGLAS GS 245, PLEXIGLAS GS 241 is used for glazing aircraft. These materials have excellent optical properties, mechanical strength and fracture resistance, low weight and surface rigidity. Additional intermolecular bonds make plexiglass resistant to environments that cause cracking.

The material is produced in both colorless and tinted transparent versions. Thickness - from 2 to 85 mm. Plexiglas for aviation PLEXIGLAS GS is certified in accordance with aircraft industry standards. The main area of application of aviation plexiglass PLEXIGLAS GS:

- glazing of ultralight aircraft;
- glider lights;
- glazing of helicopters;
- airplane lights;
- glazing of commercial aircraft cabins;
- lights and windshields of fighter aircraft;
- multi-layer windshields of aircraft.

The vast majority of thin-walled parts for homemade aircraft models are made by molding from fiberglass, or by drawing from sheet thermoplastic plastics. Recently, the range of materials available for working on hoods, wheel fairings and similar parts has changed and expanded significantly. Simultaneously with the advent of polystyrene and ABC plastic, many of the previously popular technologies began to fade into the background. Thus, the range of use of composite materials was limited only to highly loaded parts (fuselages of cross-country gliders and large model aircraft, helicopter bodies). In mass-produced kits, all molded sheet “small things” became plastic.

Of the modern common thermoplastics, the most durable is ABC plastic, which is now easy to buy in some model stores. It has one important advantage - it is not soluble in acetone. But buying this plastic even in Moscow is not an easy task. It is easier to obtain polystyrene sheets 1-1.5 mm thick. It, although not as strong as ABC plastic, in most cases satisfies all the requirements of modellers.

Let us immediately note that commercially available polystyrene sheets have much higher viscosity and reduced fragility compared to conventional household polystyrenes, and also that they are excellently glued with cyacrines.

White polystyrene is usually used. For copies it is better to look for a silver one. Painted plastic parts of this color take on a very realistic appearance as the coating wears. For the manufacture of transparent parts, plexiglass with a thickness of 1-1.5 mm is still best suited. But here we can also think about transparent polystyrene, although its light transmittance is somewhat worse.

In factories and more or less equipped workshops, the vacuum method is most often used for drawing plastics. In modern times, all vacuum pumps that could be privatized have already been privatized, and what can be bought is expensive. Therefore, let’s consider the most “home” technology.

As a tool, first of all, you need a blank (punch). It is made from linden, balsa or dense foam. The balsa blank must be primed to harden the surface. A suitable primer composition can be prepared by adding talc (or baby powder, which you buy at the pharmacy) to the nitro lacquer. By increasing the talc content, a putty is obtained, with which it is easy to correct surface defects. If dense foam plastic is used, it is necessary to cover the blank with parquet varnish or epoxy resin diluted with acetone.

The working surfaces of the blank should be rubbed with stearin (candle) or polish, wait about an hour and lightly rub with a woolen cloth. In this case, the stamped plastic will slide more easily along the surface of the punch and at the same time the local thinning of the material will decrease.

There are several extraction methods, each of which requires its own additional equipment.

First way. Used for shallow drawing of small parts. (Hereinafter, it is assumed that the products have only positive curvature over the entire surface). The thermoplastic sheet is crimped from two opposite edges with strips of plywood 4-10 mm thick using screws. Using two pliers, the sheet is held over an electric stove, heated to a plastic state, and then the entire blank or part of it is manually covered with it. Instead of pliers, you can use clamps, or make special handles in plywood frames, which will allow you to apply more force.

It is advisable that during operation the air temperature in the room should not be lower than 20°C; at a lower temperature, the plastic quickly cools down and loses its plasticity. If, after contact with the blank, the material manages to harden even before the end of the drawing process, the punch can be heated in the oven to 50-60°C (this does not apply to foam plastic blanks).

The disadvantages of the method include the fact that when heated, the sheet narrows in the middle, and its edges turn up. This forces you to cut out the workpiece with large allowances.

Second way. A frame is made from plywood 4-10 mm thick so that a punch passes through it with a gap on the side equal to 1.2-1.5 times the thickness of the plastic. The working edges of the frame must be rounded and carefully sanded. The bars are nailed to the frame, which will serve as its base. The width of the plastic workpiece is taken to be three times the size of the hole in the matrix. The plastic is heated until completely softened (at the same time it shrinks greatly), placed on the frame, and the punch is pressed into the hole of the matrix with hands or a clamp. Without releasing the punch, the plastic is allowed to cool, after which the finished part is removed from the blank. The general advantage of this method is minimal thinning of the material.

Sometimes folds form on the product. This depends on the shape of the part, but can also be caused by an excessive gap between the die and the punch, or insufficient heating of the plastic.

Third way. In this case, two identical matrix frames are made. The stamped material is clamped between them, as in the first method. If the matrices with plastic are heated in an oven, then the frames can be absolutely identical. The temperature should be selected experimentally, starting from 70°C.

Sometimes, especially with small part sizes, it is more convenient to heat the plastic over an electric stove. This will allow you to observe changes in the state of the material. In this case, one of the frames (calibrating) should have a gap of 1.2-1.5 times the thickness of the material along the contour of the blank, and the second - about 7 mm (the matrix should be held above the tile with the frame facing down with a large gap). When the plastic begins to sag, it is ready for drawing. Strong evaporation of material from the surface is a sign of overheating. When installing the punch on the table, be sure to use stops to prevent excessive drawing depth (otherwise the part may turn out to be too thin). To reduce the thinning of the plastic, the tightening of the bolts holding the frames together can be reduced so that the material can be pushed out into the exhaust area.

Fourth way. It is used when the product has protruding elements or recesses (for example, ribbing on the hood). Again, it is necessary to make a matrix. Its internal dimensions should be greater than the dimensions of the blank-punch by the thickness of the material. Achieving this using template processing is not easy, so you can resort to a little trick. The blank should be covered with a separating layer (floor mastic, polish, stearin), and then rubbed until shiny. Using a brush or sprayer, apply several layers of diluted epoxy glue. The number of layers must be determined in advance on a prototype of any material so that their total thickness is equal to the thickness of the plastic after drawing (about half of its original value). After the glue has cured, the surface is covered with another separating layer, and covered first with thin and then with thick fiberglass, forming a hard crust. Then the resulting matrix is removed and the “equidistant” epoxy resin coating is separated from the blank.

» Let's do transparent interior glazing

We make transparent glazing of the interior

There are several ways to simulate transparent glazing for a plastic airplane model.

1. The simplest thing is to glue the windows from the kit before gluing the two halves of the fuselage. When painting the model, in order to keep the windows transparent, they will need to be covered with masks.

The masks are cut out of Tamiya tape using a piece of tube of suitable diameter from a telescopic radio antenna, which is given the desired oval shape. I first sharpen the edge of a piece of tube clamped in a drilling machine or electric drill, and then very carefully, gradually, I squeeze it from different sides with needle-nosed pliers (they have jaws without notches), a little at a time, until the desired shape is obtained. Then I glue Tamiya tape onto a piece of hard rubber and cut out the masks.

You can also use ready-made masks from aftermarket manufacturers.

2. If the windows from the set do not adhere well to the plastic, it is better not to use them, and fill the holes for the windows with transparent epoxy. A backing made of adhesive tape is first glued to the fuselage. The resin may leak a little under the tape and will need to be sanded off. Good transparency is provided by a two-component epoxy composition for making jewelry.

3. When removing the mask, fringe very often remains at the border. To avoid this, you can do without masks: paint the fuselage before gluing, glue the windows, glue the halves of the fuselage and paint along the seam, trying to avoid a step. I did this on Boeings (767, 787), SSJ-100, Tu-154M from Stars . Very labor intensive, but effective.

4. But most often I do this - I don’t glue the windows in at all, and after the final blowing with varnish I apply liquid glass Microscale Krystal Klear . Using a toothpick, I apply a little of the compound around the perimeter of the window, and then fill the opening from one edge to the other. After drying, a thin transparent film is obtained that imitates glass of large scale thickness.

If the walls of the fuselage are thick, it is necessary to remove excess plastic from the inside in the area of the windows so that the liquid glass is not drawn in deeper. If the windows are round, you can carefully countersink them with a thick drill; if they are oval, remove them with a cutter (drill).

Here is a photo of Zvezda's SSJ-100 with both window options: original glazing (above) and liquid glass (below) - I assembled the two models differently specifically for the experiment.

Rsingle glazing (top) and liquid glass (bottom)

Sometimes modelers simply apply decals on top of the window openings and fill them with varnish.

Laser decals on Magic Touch paper have a thick and durable base, while silk decals have a very thin varnish layer. Once dry, it stretches and becomes brittle. Over time, after six months or a year, due to changes in temperature and humidity, some windows may break. What is good about liquid glass is that it is not excluded when using this option, and if over time the windows begin to burst, nothing prevents you from carefully cutting and removing the decal from the window openings and applying liquid glass.

I almost always paint models with semi-matte varnish, so in order for the windows to have a different texture, I cut holes in the decals for the windows using the tip of an OLFA cutter with a new blade, making two or three cuts around the perimeter of the window. When the decal is thin and the windows are small, I simply pierce it with a toothpick and then “cut” it on the edges of the windows. If the decal is welded, then nothing breaks when cutting.

I fill the windows with liquid glass after applying the varnish, then the windows stand out not only with transparency, but also with shine. You can enhance the effect Futura.

Futura is also very good to use when translating decals.

The cockpit cover decal practically does not stick to the “bare” transparent plastic. So much so that after drying and trying to blow out the model with varnish, it can simply fly away like an autumn leaf. After I had such an incident, I glued the windshield decal onto transparent plastic only on Futura. Well, then there’s more varnish on top.

A beautiful transparent canopy of a model airplane without a “vacuum”? - Easily!

Why make your own glazing for a model airplane?

High-quality glazing of the cockpit and other transparent parts in an airplane model plays a vital role in the visual perception of the finished model - after all, the canopy of a fighter plane or the glass of the pilot's cockpit of an airliner is most often the first thing the viewer's gaze stops on (as in communicating with a person, his eyes are the first thing what the interlocutor's gaze stops at). Therefore, poor-quality glazing can immediately set a lower level of assessment of the model, which is difficult to correct with an elegantly executed chassis or many small details inside the cabin - which, moreover, will also be difficult to see through a cloudy canopy.

To the cardboard models produced by leading publishing houses, as an optional addition, ready-made lanterns and other glazing parts are increasingly being offered, which can be purchased without the hassle of making them yourself. However, firstly, ready-made glazing parts are not offered for all models available for sale, and secondly, many models are offered for assembly in an “electronic” version for self-printing - in this case, count on the opportunity to purchase ready-made glazing parts for the model It’s not necessary at all.

As a rule, a cardboard model includes patterns of glazing parts. These patterns allow you to make a cockpit canopy or parts of it from pieces of transparent film. It is usually possible to make a faceted canopy in this way, consisting of flat glass or single-curvature glass (such as that of the German Bf.109 fighter), and it looks no worse than the real thing:

However, if the canopy or its parts are formed by surfaces of double curvature (such as the convex canopy of the American P-51D fighter), it will no longer be possible to make a believable canopy from a flat film: noticeable cuts and joints of flat sections of the film will spoil its appearance and make it unattractive and inadequate faceted shape:

If there is no opportunity or desire to purchase a ready-made lantern for the model, and if the glazing patterns included with the model for cutting out of flat transparent film do not allow you to get a beautiful lantern, all that remains is to make it yourself - this is what I usually do.

Hot hug method

The only acceptable and accessible home method for making a transparent lantern from a polymer film is to heat the film to a softened state, in which the film easily changes shape, but still remains a film (that is, does not melt) and then give it the desired shape. To give the film the desired shape, a pre-made punch - a “blank” - is used, which has the exact shape of a lantern. At the same time, there are two ways to give the film the desired shape:

usage vacuum chamber(see, for example, the website of one of the well-known manufacturers of vacuum equipment and the illustrations on it);
simply covering the “blank” (punch) with heated film, the so-called "hot tight".

The first method is universal, but requires a vacuum chamber, the design of which is relatively simple, but which requires skillful handling. The versatility of the “vacuum” method lies in the fact that it allows you to cover a punch of almost any shape with a heated film (except, perhaps, a closed one), including those with concavities, on which the heated film will lie being “sucked” by the vacuum created by the film connected to the camera. hood.

The second method is not so universal - it does not allow the heated film to be shaped with concavities, since it does not use air rarefaction (vacuum) and there is no way to “press” the heated film into the concavity of the punch. In a nutshell, the method consists of covering a punch that defines the shape of the required transparent part with a heated transparent film so that the film fits tightly to the punch over its entire surface. The cooled film retains the shape of the punch. In this case, a vacuum chamber or any other means is not required that presses the film against the punch during the cooling process - the film fits around the punch solely due to its own tension. The method is suitable only for convex shapes and, accordingly, for fitting convex punches - more precisely, not necessarily convex, but necessarily non-concave - without sections of negative curvature in two directions simultaneously.

I often practice this method and in this article I offer a description of the process of making a lantern using the “hot-fitting” method the way I do it.

So, I'm building a model and I need a convex canopy for it. Usually this is a model on a scale of 1:32 or 1:33, the canopy has quite “tangible” dimensions - from 1 cm in each dimension (the “smallest” are the canopies of the Soviet Yaks and MiGs of the war years, but they are not less than 1 cm in these scales, counting from the “rails”). The sequence of my actions is as follows:

make a punch ("blank"),
choose a suitable transparent film,
prepare the punch and film for tightening,
heat the film to a softened state and cover the punch with it,
Allow the film to cool without removing it from the punch, then separate the formed film from the punch and clean it.

I then cut out the canopy made in this way, mark the places where the binding will be glued and glue the binding, do the final finishing and install the canopy on the model.

Punch making

First of all, I take out the materials from which I will make the punch:

good hard cardboard about 1 mm thick for making a frame, PVA glue for gluing and priming and soft wire 0.5...1 mm thick for reinforcing the frame,
gypsum (alabaster) for the initial filling of the frame,
latex or acrylic water-based putty for “finishing” the plaster punch,
spray acrylic for final finishing of the punch.

The most expensive product in this set is the spray acrylic; Below I write that it can be replaced with the same PVA or any available transparent varnish - acrylic is needed in order to obtain a smoothly ground hard surface of the punch, so any suitable replacement is possible. Next in price comes PVA - you can use a quality that is not as good as shown, but you should not buy it in office supplies - it is very bad there; It's better to buy a jar at a hardware store. Putty and plaster cost the price of a bottle of good beer.

I make the patterns for the punch frame using the available prototype drawings, also taking into account the installation location of the finished lantern on the model and the related parts (binding). As an example, this is what my patterns made for the P-51 (A.Halinski, Military Model 5/2005, 1:33) and Yak-3 (GremirModels, 1:32) look like:

The principle of the frame structure is simple: a central longitudinal former, forming a longitudinal contour; transverse formers along the edges of the canopy; intermediate transverse shapers along characteristic sections. Frame patterns take into account the thickness of the film (I usually use a film 0.1 mm thick) - that is, the contours are made with an indentation “inside” by the thickness of the film, so that in the future the resulting lantern has exactly the outer surface that is needed.

These are examples of patterns that I had to make myself. However, some cardboard models include frame patterns for such a punch - an example is the Fw.190D model from GPM:

Making the punch frame from these patterns is not difficult - although in this case I would add a couple of the aforementioned cross formers along the edges of the canopy.

I glue the frame cut out of cardboard and pass a piece of wire through it as reinforcement (it subsequently prevents the plaster from falling out). I grind the edges of the frame and paint them with a colored marker - this is necessary so that later, when grinding off the excess plaster, I can stop in time. Finally, the frame is completely primed (coated) with PVA - to give it some water resistance.

When the frame is ready, I spread the plaster and fill the frame - with some excess:

You should not feel sorry for the plaster - it sets quickly, so it is better to immediately spread more and so that the entire frame is filled. There is no need to remove the excess - all the excess can be sharpened later. The frame filled with plaster is left in a warm place until it dries completely - visually this will be noticeable by how the initially wet and dark plaster lightens and takes on a “dry” appearance. Typically, at room temperature, a medium-sized punch dries out in a few hours.

I grind the dried workpiece with a rather coarse file until the ends of the frame appear. Then I sharpen it with a smaller file:

When the workpiece has taken the desired shape, I cover it with a thin layer of putty, dry it again and sand it with medium-grit sandpaper until the final shape is obtained. Then I cover the workpiece with several layers of aerosol acrylic and sand it with the finest sandpaper (“zero”). The punch is ready:

Instead of aerosol acrylic, you can use any other transparent varnish, and you can cover the workpiece with a brush. You can also coat the workpiece with PVA glue instead of varnish. In all cases, several layers should be done with intermediate and final sanding. This is important: the unevenness left behind will definitely “imprint” unsightly on the finished lantern in the most visible place.

Selecting Transparency Film

To make the lantern, I use polyester film, which is used to make many things these days - plastic bottles, various types of packaging, and so on. Other types of transparent film (polyethylene, lavsan) are not suitable for this purpose. The film selected for the manufacture of the lantern must have the following properties:

be absolutely transparent, free from unevenness and scratches,
as the temperature rises, transition as gradually as possible from a hard to a soft state without melting;
have a thickness of approximately 0.1 mm.

The first requirement is obvious; the second requirement is important because I heat the film over a gas burner, where the softening of the film can only be controlled visually. If the film quickly goes from a softened state to a molten state, it is difficult to work with.

The first and most accessible is films from some packaging. Such films always satisfy the second condition - as the temperature rises, they soften gradually and there is no danger of “overheating” the film until it melts (this is due to the fact that packaging films do not contain additives that increase their strength or thermal stability).

The first condition is worse: finding packaging that is clean and not scratched is quite difficult. However, I use film from the packaging of Korkunov candies - boxes with these candies, the lids of which have “windows” with film glued into them, are additionally packaged in cellophane, so the film from these boxes is protected from dirt and scratches and is usually perfectly clean and transparent :

This film also has just the right thickness - just over 0.1 mm.

Apparently there are other things packaged this way that can provide good clear film. However, considering that my family buys candy more often than I build models, I am provided with excellent film for years to come.

If you find a suitable package that is not flat, you can “release” it by gently heating it over a gas burner:

The heated packaging will quickly take a flat or almost flat shape, because it was made in some factory from a flat sheet of polyester - just the vacuum molding method mentioned above. This remarkable property of polyester film - to take the shape into which it was cast (most often, as in this case, the shape of a flat sheet) - will be further noted in connection with the ability to “pull” a lantern several times from the same segment films).

However, you should evaluate the “released” film for cleanliness and the absence of scratches - during the “release” process they may become apparent.

Second option - films used for bookbinding:

These films are usually clean and quite flexible and seem to be suitable for use (although I have not had to use them). In addition, when searching on the Internet, I did not find any offers for such a film thinner than 0.2 mm - and this is a bit too much. I think films thinner than 0.2 mm are simply rare - for the simple reason that this is too small for a strong binding ("crust"). Although, perhaps, somewhere there is a thinner binding film.

Third option - films used for printing transparent materials:

Although these films are high quality and clean, they have two drawbacks.

First, they have a layer on them designed to hold ink or paint while printing. This layer makes such films not completely transparent; it must be removed. From a transparent film intended for inkjet printing, this ink-receiving layer is washed off with warm water, but the remnants of this layer have to be removed with acetone - which is not very beneficial for the film.

Secondly, these films are manufactured for use in projectors, and therefore contain additives that increase thermal stability. Because of this, such a film does not immediately soften when the temperature rises, but it easily passes from a softened state to a molten one - it is quite difficult to keep track of this. As it heats up, it happens that the film warms up, heats up, heats up... and then at the moment when it seems to be soft and begins to ripple, it suddenly melts in the very middle. It looks something like how a jammed and stopped film in an old movie projector is instantly melted in the middle by a beam of light.

After the first experiments, I do not use such films - although they have an ideal thickness of 0.1 mm.

Preparing the punch and tight-fitting film

Preparing the film involves cleaning it from debris and dust; It also makes sense to wash it with detergent (in other words, soap). You should also choose a piece of film so that you can grab the edges with both hands and have enough space between your hands (for the examples below - approximately 10 x 10 cm), that is, the ideal length is 20 x 10 cm or slightly less.

Preparing the punch consists of covering it with some substance that would prevent the heated film from interacting with the surface of the punch (in other words, so that the heated film does not stick to the punch during hot tightening and is easily separated from it after cooling). For this purpose I use paraffin - an ordinary candle. I take a candle and rub the punch with its end so that it is completely stained with paraffin. Then I rub the paraffin with my fingers so that a smooth waxy layer of paraffin comes out to the touch, and I lubricate and shake off the excess paraffin - you need to leave a minimal layer, no lumps. It is best to rub it with your fingers, since the temperature of the finger softens the paraffin and easily smears (and the excess is smeared). You can hold the punch over a gas burner with low gas - so that your hands are hot, but no more.

Paraffin acts as a lubricant between the punch and the film - it ensures that the cooling film does not stick to the surface of the punch. In addition, due to its low thermal conductivity, paraffin does not allow the heated film to cool quickly when applied to the punch - if it cools quickly, it will not have time to take the shape of the punch.

It also plays the role of another leveling layer, but this is not so important if the surface of the punch is already smooth and clean.

Warming up the film and wrapping it around the punch

To heat the film, I prepare old warm leather gloves, a gas stove divider and a wooden block. I put the divider on the burner of the gas stove and turn on medium gas, letting the divider warm up.

At this time, I place the punch on a vertical wooden block - so that I can completely wrap the punch with a soft film with my hands. Correct installation can be checked by holding the edges of a piece of polyethylene of the same size as the selected sheet of film with both hands and pulling it onto the punch. If there is still some headroom left at hand to stretch the hot film, everything is fine; if not, you should choose a higher bar.

I take the sheet of film by the edges with gloved hands and begin to heat it over the burner. The moment the film softens during the heating process will be clearly visible - the film will begin to stretch elastically in your hands, and its surface will begin to warp and ripple. To increase the temperature, I lower the sheet lower to the burner, to lower it, I lift it. At the moment of sufficient softening of the film, I quickly transfer the film to the punch standing on the block, put the hot film on the punch, lower the edges of the film from left to right below the punch and pull the edges down until the film completely lies on the surface of the punch - that is, I wrap the hot film around the punch film. As soon as this is achieved, I freeze and start blowing on the film so that it cools down faster. A minute or two is enough for this.

This technique may not work the first time. No problem - I remove the cooled film from the punch, "release" the film over the gas back to the flat state (see above, which shows how this is done to "release" a non-flat package), and do the tightening again. This can be done as many times as necessary - until you get a perfectly covered punch, and you can use the same piece of film several times - until it is worn with paraffin and distorted to an unacceptable state. In this case, you should monitor the sufficiency of paraffin lubricant on the punch - its surface should be waxy to the touch. If necessary, paraffin can be added.

Cooling the film, removing it from the punch and cleaning

The film should be kept on the punch for one or two minutes so that it cools completely. Then I remove the cooled glass from the punch (usually not much force is required if it is well lubricated). After this, I wipe the glass with a soft rag (without scratching!) or cotton wool and wash it with detergent (soap) to remove traces of paraffin and other dirt that may appear.

The lantern is ready - now you can cut it out, glue the necessary parts, bring it to perfection and glue it in place.

Addition: the “hot hug” method from Andrew Inwald

A freely available Spitfire Mk.Va model kit by Andrew Inwald recently appeared on the KARTONBAU.DE and PAPERMODELERS.COM forums:

An absolutely wonderful part of the kit is the original way of drawing a lantern from film, and the kit itself contains all (or almost all - with the exception of putty) the parts needed for this (more precisely, the patterns for these parts).

The author offers patterns for the punch in the set - not only the frame, but also the casing of the punch:

According to this idea, gypsum is not needed at all, and at the same time, due to the frame corresponding to the geometry of the model, the resulting punch will have almost exactly the shape that is needed. The process of making the punch and then the lantern is illustrated by the following pages of instructions (I have reduced them and drawn the explanations in Russian):

Agree, everything is simple and logical. It is enough to lightly putty and sand the glued punch - and you need to sand it until the casing appears (this is important, because the joints of the punch casing determine the desired shape of the glass and an extra layer of putty will distort it). Next, from the punch (on the sheets I called it “assembly”) a simple but original device is made, which allows, firstly, not to burn your hands when heating and tightening, and secondly, to fix the cooled glass on the punch - it’s not only needed in order to give shape to the glass, but also in order to glue binding strips along its edges.

True, I must say that my first (and only) attempt to use this method was unsuccessful - pulling the film up is not very convenient, and gloves will be required anyway. Nevertheless, the method deserves attention.

In contact with

This story is being written piece by piece. Well, the plane is also built piece by piece. And now, after two months of silence (and after watching the video, which really motivated me), I resumed work on installing the canopy in the fuselage. The canopy was one of my problems - after all, the fuselage was originally made without it. Well, this is not such an insoluble problem. I made a 3D model of the canopy and tried it on the 3D model of the La-7 that I once made for the simulator. If you make a neat cutout on top, the canopy will fit perfectly into the fuselage. And we will make a balsa lantern.

Making a canopy for a radio-controlled aircraft La-7

First of all, it was necessary to make a 3D model of this lantern, which I mentioned above.

There was an idea to use this 3D model to obtain drawings of a balsa frame, but this idea failed - it turned out to be much easier to make the drawings yourself from scratch.
I have strange drawings. However, this is a working version - the print version looked a little neater (though it didn’t make it any clearer). Having transferred it all to balsa and cut it out, I got a handful of parts that were to become the canopy of the La-7 radio-controlled aircraft.

Next, I printed out the life-size outline of the lantern and began an exciting activity (by the way, no sarcasm, no irony - this is a really exciting activity - assembling a balsa frame using superfluid superglue)
At the same time, we begin to “open” the body, carefully, trying not to cut off too much. Then we break down these partitions.

We try on the semi-finished frame for the cutout. It turns out quite well

We continue to work on the frame, not forgetting to try it on (to satisfy our own eyes). I wanted to immediately cover the removable part of the lantern with transparent film. Speaking of film, this is acetate phototypesetting film. The same one on which they print templates for me to make printed circuit boards for electronic devices. I asked that company for defective sheets - they provided me with a whole roll. This film sticks perfectly with superglue! Wonderful material for lantern glazing

Then I stopped working for two months, but after I saw one video, my conscience awoke and I resumed work. I strengthened the weak points, installed side walls, broke out the “non-replica” fuselage front and made a “copy” one (like a real La-7). Although, it seems, the proportions are still a little off. By the way, I worked without drawings - trying on pieces of balsa in place, cutting them off and immediately gluing them in place.

Well, I couldn’t resist trying it on.

And then the most interesting part. The fact is that I still haven’t decided on the coloring of the La-7. I want something dark, so that the glue seams will be hidden under a dark layer of paint (oh, I have a feeling that they will still be visible). But you need to decide, because the frame of the lantern needs to be painted BEFORE covering it with a transparent film. In general, following the advice, I paint everything black. I protected the ends under the glue with tape and spray painted everything. I painted over the ends with a marker (tests showed that acrylic paint worsens the strength of the adhesive joint, but a marker does not).

Gluing the film to the lantern is very, very simple. We place the frame end-to-end on the film (before that, we try it on to see how the film fits on the frame - will it be enough? Moreover, we give a tolerance of about a centimeter at the edge - so that the glue does not get on the table. And pressing the frame to the film, we pour superfluid superglue into the crack. It instantly flows between the film and the balsa frame - and in seconds connects them tightly.

And then we wrap the frame on film. This is how it is in this series of pictures that I combined into animation.

Then, holding the film taut, we work with the applicator along the frame, pouring glue between the film and the frame ribs. The glue, of course, remains on the film, but you know, it’s not visible from a meter away. After this, we cut off the excess film and repeat the operation for other surfaces. Here I was proud of myself - because my film lay perfectly on both sides - the front and back of the lantern. (I mean the geometry of the frame - the film lay smoothly on all the edges without distortions.)

I had to tear off the film from the removable part of the lantern (with great difficulty - the film did not want to come off - it simply came off in pieces), and after painting it, re-cover it with film.

The result is in the photo below. To be honest, I don’t really like it (but my wife, on the contrary, approved). And I’m afraid that I shouldn’t have painted the lantern black. However, if I suddenly don’t like it at all, I’ll redo it. The technology has been worked out.

Next we need to finally finish the tail section. Think about the tail wheel (it still won’t retract - but it simply must be controlled!), think about the system of rods for the rudder and elevator, lay it all out - and sew it up.

Well, or do the front part of the fuselage. I plan to make it from solid pieces of foam plastic using special materials. machine with a nichrome cutter (which is yet to be done...). There are also thoughts about mounting the motor, which I don’t have yet...