I’ve just looked through my writings and now I want to highlight the subtleties and techniques I haven’t mentioned before.
TECHNOLOGY FOR BUILDING TRAINING CROSS-SHAPED STYROFOAM AIRCRAFT

I’ve been down the extremely thorny and lengthy path of designing and building this sort of aircraft, and I hope my experience will help you avoid trouble. Also, I have some news for you.

TITAN
This one is great for gluing ceiling tiles, paper, wood and certain types of plastic. What I really like about it is an opportunity to use it in a variety of fashions. Put some glue (do not thin it) on both surfaces, wait for 5 minutes and connect the parts; if you want it to bond quickly, wait for 10 minutes and put the parts together; this way you can fill up tiny gaps between the surfaces. This glue is reasonably elastic, and no part of the ceiling tile will be ripped out in case of a crash, and it fills in all pores. Remove excess glue with your fingers. Before gluing plastic parts, rub the surfaces with a piece of big-grit sandpaper. You can thin the glue down with pure alcohol. However, I don’t recommend you to do that, because it will dry for too long. Use any container with a thin nozzle for more convenient gluing.


UHU Epoxy Adhesive
Thanks to its fluidity, it easily penetrates into the texture and can be mixed in small amounts; it won’t become glass-like and will retain its slightly elastic structure. I recommend that you use pieces of adhesive paper, which you throw away right after use. You can take it out into the field and use it in case you need an occasional repair, and your aircraft will be ready to take off in 15 minutes.

I use a glue stick when I need to glue a template to a ceiling tile. If you do not put too much glue on paper, none of it will be left on the tile (when you remove the template).

Washi tape becomes irreplaceable when you need to fix parts while gluing, and it won’t stain. You can wrap servo units in it and just glue them in the right place. The adhesive layer won’t stick to Titan or epoxy.

The downside of it is that it leaves dull traces on the ceiling tile if you press too hard.
I have a set of templates – they are all separated at joints, and adhesive tape holds them together, so that you can take it apart and put together any time.

Here is a little folder for templates.

Mark it with the softest 8B pencil you have. Hold it flat and do not press too hard. Some guys use markers, but lines are often washed away by glue, and the whole thing looks shabby in the end. Also, you can glue (or pin) the template to the tile using a glue stick (or pins) and cut it out.

Now, a little trick: when cutting out circular parts, pull out the blade, bend it a little and cut the surface, holding it flat again. In this case, the blade will go deep enough, and the cutting will be done by the middle part of the blade, so your tile won’t crumple or tear. Make sure it is always sharp enough and replace blades regularly! Here is an example of what a blunt knife will do to your tile:

OLFA blades are durable and very sharp.

Sorry for the yarn, I just wanted to let you know how and why I use the tools and techniques.

Well, it’s ok, let’s keep to the subject. I built the wings using two layers of SOLID board (the more attractive side outwards, 8mm thick). The wings consist of a base and thin boards with a cut-off trailing edge. Then I put thin strings of glue on my parts: lateral on one part and perpendicular on the other; right after that I glued the edges of the two halves. Then I gave it a 5-minute break, put the halves together and taped the whole thing up on both sides.


Now listen how I use masking tape (painter’s tape). Glue the edges and connect the parts. Attach the adhesive tape to one half, then pull it up and attach it to the other half. The plate will definitely bend; do the same thing on the opposite side, and the plate will bend back into its initial shape. Then put some weight on it and leave it for about an hour to dry. That’s how I built the wings, and it bought me an hour to build the tail.


I made two replicas – a 4mm- and a 3mm ones in thickness, and the resulting weight margin was 1,5g. The bigger the distance between the tail and the center of gravity, the harder it is to compensate it at the front. Unfortunately, I chose the 4mm version – I shouldn’t have done so. Then I glued in the spar. Although I’d always used thin bamboo sticks, this time I used a 1x3mm carbon strip. Then I polished it with a piece of fine emery cloth, put on a bit of ‘frill’ and cleaned it with alcohol.

Next I made a cut in the stabilizer for the spar. I recommend using a very sharp knife, or you won’t be able to make an ideal 0,5mm cut. I put some glue around the cut and inserted the carbon strip into it without waiting for the glue to dry. I dipped my finger into water and spread the glue over the area, so the glue wouldn’t stick to the finger. After removing the glue leftover, I taped it up on both sides and put it under pressure.


Then I glued the 750х0,5х8 carbon strip into the wing. Although I had done it earlier – right after putting together and drying the wing halves – please, let me tell you about it now. As I have already said, it is better to cut through a glued-over surface before it dries completely. I did it after it dried, and that was pretty tough. Here are two types of the spar – one cut out of a light ruler and a carbon one. That was the first time I was using a carbon spar.

After a little rub with an emery cloth and a bit of alcohol cleaning, I pressed the spar into the glued-over cut. Here is how you can roll off excess glue.

Hinges

I had an old laptop tape screen protector, so I cut a strip out of it and folded it in half along its length at the center line. It was too smooth, so I used the cloth again, then made holes using a blunt needle (to make the holes less smooth for better binding), turn it over and do the same on the other side. Next, I cut the strip into smaller ones and rounded the edges, so that I wouldn’t have difficulty inserting them. I honed my knife, so that I could cut slots for the hinges. Now the blade’s point is sharp enough.


Then I line-marked the middle of the edge and cut slots in it, swinging the blade slightly up and down, glued the hinges’ edges on both sides and inserted them without waiting for the glue to dry. It did not take much glue, and it spread well as I inserted the hinges. You can move the hinge a little. Then remove excess glue and apply pressure. Wait 15-20 minutes before gluing it into the fuselage.

Prepare the fuselage, put glue on the hinges’ tips and attach them at an angle one by one without letting the glue dry. The hinges should be angled a little (I’d used to bend them), just for better bonding.

Remove excess glue, bend the stub alternately to each side, check the connection and use pressure. Now let’s get down to the lower part of the fuselage; since it is immediately observable from the ground, I make it out of a 4mm piece of SOLID, the attractive side facing the ground. Because it exceeds the sheet size, you have to piece it together; I advise you to make a seam right over the wing – the thickest and strongest part of the plane. A one-piece beam should be used on the tail. Line it off, then measure it out and and cut it into parts.

To ensure perfect verticality, I use taped-up foam cubes (I used tape instead of glue, so they wouldn’t stick).

Now that I got it on my ‘signature’ holding frame, I glued, cube-fixed and taped the whole thing up. Then I gave it a 10-15 minute break to let the glue dry. When I pressed, it bonded almost instantly.

Then I upgraded the hinges a little: I made a hole for better folding. I removed excess glue using an alcohol-saturated cotton swab. Do it right away, because alcohol evaporates quickly. The pencil lining can be easily removed with an eraser.


Now let’s see how I upgraded the hinges. I already said that I made holes in them for better bonding. However, instead of the routine of piercing them with a needle, I crafted a perforator wheel using a clock cog and honed its teeth. Also, you can use a tracing wheel, which is used for transferring patterns to different pieces.

When I wheeled it on one side, the plastic curved, but it straightened once I wheeled it on the other side. The insertion of the hinges into the slots has received a little upgrade too: they are flexible, and the perforation ensures better bonding as it gets caught on the slots’ edges.

Bend the aileron down, catch the loop with pincers by the middle cut and insert it. Everything goes straight and smooth.




Next thing you do is fix the ailerons' torque rods. You’ll need a piece of 1,5mm wire, a 3mm piece of heat shrink tube. Put the tube on the wire and heat it up with a drier, but don't let the tube squeeze too tight around the wire. Then bend and flatten it, thin off the rod’s end and glue it to the aileron; cut a groove in the wing and glue in the rod. Tape it all up beforehand. Don’t let the glue get inside the tube.


Cut out vertical pull rods for the ailerons according to the size of the servo’s arms, get the shrink tube on, zero out the servo using a servo tester and heat it up with a lighter very, very carefully. A drop of cyanoacrylate will contribute to firmness.

Because you have already installed the vertical part of the fuselage, working can be inconvenient. To avoid that, build a makeshift holding frame. Measure it out in such a way as to leave enough room for the plane’s flight control surfaces to maneuver freely. Transport it in the ‘as is’ shape. Do not take the plane in your hands too frequently while building it, because the foam is very light and brittle. Move it by the frame.

Now, let’s move to the next stage of our rock-the-world mission. Now you are going to tailor and mount the upper vertical element of the fuselage – the cockpit.


About cutting holes.

You can order or buy tools, but I wanted it all for free. I found old capacitors, an empty hair spray container and a plastic cover. Aluminum is too soft to retain sharpness, so you’re going to have to saw it instead of cutting it. Then hone the edges and make small perpendicular cuts with a knife to make teeth. Now you have a little saw. To drill holes, I apply rotational movements. Not bad at all for the ceiling tile.


The capacitors feature ‘pushers’ for ‘extraction’ of cut-out parts, and you can use circular plates as well. All reinforcement mounted on the nose section should be glued with the Titan, and the motor should be mounted on a plywood frame, which I epoxy-glued to the plane. Tape the whole thing up.


I’d spent a long while practicing installation of servos, control horns and pull rods. The method I’m offering you, I believe, is the simplest and most helpful in avoiding backlashes and inaccuracies, which may occur as you install flight control elements. Then I lined off the area for mounting control horns and servos. I also increased the length of pull rods by 2cm, and I’ll tell you why later.

I make control horns out of toothpicks, bamboo sticks and 1,5mm carbon sticks. For better bonding, I cut little plates out of plastic cards and drilled 1,5mm holes in them at a 45-degree angle. Then I epoxy-glued them to flight-control surfaces and eventually pierced through the ceiling tile as I inserted it. The horn should be positioned at a 45-degree angle to the surface, and the upper edge should be placed right above the break line. The height of the horn should equal the length of the servo’s arm. Connect the horn to the pull rod using a piece of shrink tube and a bit of cyanoacrylate, then install a latch on the servo arm at the other end of the pull rod. Here are the 2cm, which prevent a slip from the shoulder. Finally, I assembled the whole system in a suspended state.


And now the most exciting part of it. Let me tape all those rudders and elevators to the zero position, then wrap the servos in double-sided tape, zero out all the arms using a servo tester and glue it to the fuselage without accidentally moving a thing. That’s it! Nothing really big, just don’t let your hands shake at the last moment!

You can easily move this whole system from a damaged aircraft to a new one, just take the control horn out of the foam very carefully, without taking it from the reinforcement area, remove the dried epoxy, and glue the horn into the new place. So far, none of the crashes I’ve had has resulted in control horns being torn out or pull rods breaking.

Then I cut out tail reinforcement plates, measured it out, cut off the edges at a 45-degree angle, glued them in and taped the whole thing up. The trick significantly reinforces the tail section to generate a spin. I made two mistakes: first, I messed up the ailerons’ pull rods, I should have fixed them closer to the fuselage and they would have stabilized beneath the reinforcement plates. The second mistake – I should not have stretched the reinforcement plates over the whole width of the wing up to the nose, as 1/3 of the trailing edge’s length proved enough. I should confess those were not the right things to do. When the glue dried, I made lightening holes using a Nivea container. Then I sawed them carefully. Yes, I made them closer to the elevator, I didn’t think that further lightening would have been of any use.


About installing the ‘power’ section.
I taped up the wing, putting yellow tape on the bottom and red on the top with an overlap at the leading edge. I pulled it slightly and smoothed it out on the fuselage to eliminate bubbles. Later I realized that taping it up prior to assembling it would have been a more convenient way to accomplish it, and the whole thing would have looked spick and span.

Now, so much for the wing. But: I wanted more. And I decided to make lightening and do up the entire wing.


I did up the ailerons too. Then I cut the tape along the edge of the aileron and run the ceiling tile plate along the cut to fix it along the aileron’s edge. Next, I ironed all that and mounted it on the holding frame using masking tape. Finally, I reinforced the lower front section of the fuselage with a bamboo stick.

Next thing I built was the pilot’s cockpit. I put black tape on the Oracal lining, cut it to the radius, put it on the fuselage and cut off the edge along the contour. Repeat the procedure on the other side. You can use blue tape if you like.

Then I mounted a receiver, a battery and a controller using the Velcro fastener, which is fixed to the body with double tape. I removed the coating from my Turnigy receiver and dressed it in shrink tube, thus reducing the weight by 9,7g.

Because the nose was quite broad, the centering was focused on the angle reinforcement.

The resulting flying weight was 250-280g depending on the battery type.

Then I made a few updates: I braced the bottom plate (it had cracked all the time) and reinforced the wings. Then I fixed an motor mount made of 5mm expanded polystyrene and 5mm thick side plates on the fuselage. I glued them to the fuselage with Titan and reinforced the polystyrene mount with cyanoacrylate – a really great material. It is sticky, strong and reasonably lightweignt, and self-tapping screws hold well in it. The nose section got much stronger, and I pretty much crash-tested the technology on indoor aircraft types.


THE CEILING TILE’S BIGGEST PLUS!

It takes minutes to repair an aircraft, regardless of the degree of damage.
Watch this.







Just another crash was a good reason to demonstrate the high repairability of Styrofoam airplanes. My tool kit included masking tape, a knife, a pencil and Titan glue. Pull the knife’s blade all the way out and cut off the damaged parts, paying attention to the cutting plane. Draw the contour with the pencil using the ceiling tile. Smear it with glue and wait for 10-15 minutes, then glue it. Remove old glue from the motor mount and glue it back where it was before. THAT’S IT!

The whole thing took 20 minutes. Try to restore balsa lacework within 30 minutes. Yes, you can, but: the glue will fully bond on the next day.




The modernization of the motor mount, which I described earlier, was great. I had a hard time tearing it apart when extracting the mount. And the impact was good enough to fold the whole nose section into one big concertina up to the wing, and the mount was still there holding the motor, as you can see on the first photo. It never let go!

The controllability of the little Sprint aircraft is above all praise. It goes very sharp and sensitive. I did a little showing off and hotdogging as a let its blades do a little grass-cutting, and here is the result. Now the damage is fully eliminated. The little grass-mower is back in service.



Boundless opportunities of kitchen-table modernization.

Now please, let me continue to chant praise to foam. Here is my good old little plane, which has seen better days. One day I decided that the rudders and elevators were bad. The upgrade resulted in the addition of flying surfaces, which I glued end to end. I can say it holds in a death grip, and the glued seam is even stronger than the ceiling tile itself, so you can use the glue without fear. I just wonder why I should have fixed that little wing… Just for a little jazz-up, I guess.

Here is my little thing flying in a strong gale, no piloting, just having a little fun dancing in the wind. The smoke in the distance is from the burning oil plant, which I’d just bombed)))


ABOUT CYANOCRYALATE



About the Great and Terrible Cyanoacrylate

I used to work as an advertiser and I’ve used all cyanoacrylate types. The one made in Germany was my final choice. It bonds very well and instantly, if pressure is applied. You can reinforce seams with it. This is how it should be used: put a syringe needle on the nozzle. Use a thick needle. Plase, note that the glue can dry inside the needle too. There are two solutions: when using it, I put a squeeze on the tube, holding the needle down, and it is not until I turn the needle upwards that I let go, and the glue remaining inside the needle is sucked back into the tube. If the glue blocks the needle on the inside, I expose it to fire until the glue inside burns out. After that the needle was usable again.

Dampness causes cyanocrylate to bond faster. If you appreciate speedy bonding, hold the part close to your mouth and breathe on it.

DO NOT INHALE THE FUMES!!!
Moist causes it to bond instantly, but in this case it leaves dull deposit. When I have to use a big amount of glue, I put some baking soda on it and do so a couple of times. That results in the appearance of some kind of plastic material, and heat is generated.

PRECAUTIONS!!!!
Please, take this stuff very seriously. I’ve witnessed tons of accidents and I should warn you. If you have accidentally glued your fingers, do not tear them apart! Dip your hand in warm water and hold for about 10 minutes, and it will let go.

Do not inhale the fumes! If you need to use a big amount of cyanocryalate, provide due ventilation. The substance may cause allergies and gritty eyes. Signs of a serious poisoning include severe dry cough, which won’t go away quickly. Some allergy relief medicines may help you a little. I coughed for about three months. If the glue gets into your eyes, call an ambulance immediately!!!

One not so slight hitch: it can destroy the ceiling tile.

Now, more about the technology.
One day I faced the necessity of balancing out the propellers, so I looked through stores and forums and realized that it was as exciting as it was expensive. I bought a simple $2 balancer, so that I could get it first-hand.


Then I fixed that funny little miracle on a magnetic mount. That was exactly when I realized that the balancer was completely out of balance. The clamps were bad, I mean, the holes lacked precision. Its only advantage was a good quality eccentric clamp. However, there was an easier way to go. I picked up a few axis pins, which fit the holes’ diameter and ground the tips using a grinding wheel (you can use a diamond wheel). Thus I made a right cone with the point in middle of its base. I used speaker magnets. This is how the propeller rotates on a hand-crafted axis. The wind was coming in from the window.


My comrade in arms had advised me to build a different machine. I followed the advice and this is what I got. I perched the blades on a level and zeroed it out with the three screws. To balance it out, I put a strip of Oracal on the lightweight blade in such a way as to overlap the front edge, and it wouldn’t come off. Some guys choose to sand the heavy blade. Well, tastes differ. I can say this contraption boasts a higher precision. Thanks for the advice, man!




To ease the soldering process when working with small-size stuff, I built a magnifier using an old lamp support, a magnifying glass from some old magnifying device. I warmed a 5mm piece of polystyrene with a dryer and promptly rimmed the glass with it. I set the glass a little deeper below the rim on the front side and applied dull black paint to reduce sideway catchlight.




TECHNOLOGIES FOR INDOOR RC PLANES.

A blade holder
It cuts the ceiling tile much better thanks to a thin blade, so you can cut out a thin strip for an accelerator. I cut a blade in two with scissors and cut off the blunt end as I work. Then I double up a 2cm wide stainless steel strip and put the same kind of strip on it from below to fix the blade.




Precautions for those going to work with carbon and fiberglass

It is mandatory that you put on gloves and a respirator. If you have long sleeves, you can tuck them into the gloves. Take care of yourselves! When you finish work, wash your hands in cold water for a long time to remove microscopic splinters. Do not scratch even if it itches hard! Just wash again. It was not until I washed my hands five times that the tingling was gone. It is also advisable to rinse the planks in cold water and rub them with a brush, so that you won’t run splinters into your fingers.

The simplest splinterer
All I had to use was a knife blade, a piece of polystyrene and cyanoacryalate. That was a fixed-size thing, and no adjustment was required.


The cutter size I needed.

You can cut not only carbon, but other types of planks as well. The base was a thick polystyrene strip, pads for the blade and self-tapping screws of an appropriate length.

The back edge of the blade should be slightly elevated to make sure that the cutter's face runs parallel to the base. Splintered parts have rough surfaces, which bond very well.


A mill for the ceiling tile.

Now, let’s make a makeshift milling device. What I had close at hand was a plastic meat grinder pusher, and it sat well on my drilling machine, and I could adjust height manually. I used a large-blade dental bur, and it cut pretty clean at 15000rpm.

First, I had to make templates. Then I put one on the just cut-out workpiece and lined it off with a pencil. I did the milling according to the pencil-drawn pattern.






Here is the result of my rock-the-world activity.





I made a feather mill - the simplest type. I cut a groove in a nail and inserted a piece of box-cutter knife into it. Then I spot-welded the blade to the nail very carefully (not to burn it through) and honed it on the vertical. Then I sanded the opposite vertical facets and finished them using a piece of ultra fine sandpaper.

That was beautiful. The cutting was faster at maximum RPM. Eventually, my plane shed 10,5g, so I guess the lightening was a worthwhile thing to do.

What was really bad was the terrible load of static foam dust left around the workplace, and I can say there is hardly a tool to remove it, as the particles get extremely sticky. I removed it with my vacuum cleaner by the skin of my teeth.

Happily, the experiment took place at my employer’s workshop. I’d either have gotten shot or shot myself if I had done that all at home. Even now I have to look for a convincing excuse, since the hose from my vacuum cleaner got pretty much laden with the foam dust as it did shoot from inside the cleaner pretty bad.

Now, one more little upgrade for my mill. I glued a transparent plastic pad (I cut it out of a CD box) to its base for better balance and to make it convenient for processing large holes. Then I put a plastic tube to the cutter head; I had bought a carpenter’s level at a local store. I also made a foam plug with a hole and inserted it in the vacuum-cleaner’s hose. I recommend that you use a vacuum cleaner featuring a control unit. That proved to be a nice way to remove the dust, except I had to do it slowly so that no particle would be left out.

And now a little detail: it is better to mill it clockwise to avoid roughness. You can use mills from a CNC machine, because they cut very well. Click here:

The holding frame
Now that one of the fuselage’s vertical facets is glued, do the same work on the opposite surface. Here is a photo showing you how I use it:





Motor frames and nose reinforcement
















Mount the motor


As I have already written, modern motor mounts are made of polystyrene. I put a rubber tube pad between the frame and the motor. It damps vibration and provides easy angle adjustment. Here is a photo of an absorber Type 1. This is where I got it from, there are also 3mm axels, I’ll use them later too.




Defining the сenter of gravity

I take great effort to invest whatever I have close at hand in RC aircraft building. This time I had a kitchen utensil holder. I cut the middle part out of it, which had hooks, and made it into a balancing machine. Although it was far from sophisticated as it did not feature a level, micrometer or GPS, the gravity center won't care about the price when it comes to defining it.


I also soldered several batteries together and taped them with Oracal. There are eight 1,2V/2700ma batteries, which I had gotten for nothing. The device lasted 2 years.

It is not always possible to highlight the arrangement of certain elements, even if you think it through and draw a sketch.




Now, suffering a complete and utter brain failure, I built a 3D model. You can craft it from paper, cardboard and even playdough.



That’s it, I guess.

I’ve told you about the subtleties and challenges of building Styrofoam airplanes, which I did not mention in my previous articles. I did write about how I build my airplanes and there you can find detailed descriptions of the technologies, so there is no need to repeat all that. Please, read my diary.

I’m all so sorry, dear aviator brothers, but I do not have any drafts of my aircrafts. When building, I do not make any thorough calculations or drafts and rely mostly on the idea itself. But if you really want some, I’ll try to provide you with them at your polite request. However, don’t expect me to just print and tailor it in less than no time. It’s going to take a little comeback to draftmanship and quite a bit of ruler- and pencilwork. I’m just sharing with you my ideas and techniques and giving you the freedom of using them to build, modify and reconstruct your RC aircrafts. Just feel free and easy!





















This is the translated version. You can read the original Russian article here.