[Herra Tohtori]

So, another fancy airplane project; this time one that will hopefully actually fly.

I have had a 500x420x23 mm piece of styrofoam hanging around for years, and I finally got the inspiration to make something out of it.



Using this image as a source, I printed it in 1:35 scale (wing span 420 mm) and proceeded to start the designing and cutting process.



I decided to make the plane in three main parts: First the wing, front fuselage and leading edge extensions, then the rear fuselage containing engines, air intakes, rear radar and the locations to where the vertical stabilizers and elevators are attached. After that I would make and attach the nose cone, cockpit canopy, stabilizers and control surfaces.



Here is the plane with two main parts partially assembled:




...and here is the current stage; the only things missing are pretty much the control surfaces for rudders and ailerons, and then add some support struts (barbecue sticks ) before final assembly.







Pretty good success, and I suspect the flight characteristics will be excellent, as it weighs near nothing - which means I will have a lot of wiggle room with ballast and centre of gravity adjustments. Basically the more ballast I add, the faster it will be able to fly. Right now it would probably glide at about normal walking pace and any wind would take it to kingdom come.

Updates as the project progresses. Any suggestions of a durable, nice looking surface material? I wonder if I could just cover it with glue and stick aluminium foil onto it... or I might go and buy aluminium tape and do it properly. Although that would boost the project's budget significantly...

[Titan]

Sweet.

[Retsof]

I don't know if foil or tape it the best way to go, you'd end up with weird ridges and wrinkles.  I'd go with something you could spray or brush on.  How does styrofoam react to polyurithane?

[colecampbell666]

I know that there's a certain glue that you can use on foam, I used it on a model plane once.

[Flipside]

There was a stage in the UK where Airfix glue was called Polystyrene glue (The UK name for Styrofoam). Ironic really, as polystyrene melts like butter under a blowlamp when it touches airfix glue...

[jedimasterseth]

hey brilliant brilliant work!!!

You could cover it with a very thin layer of plaster of paris or some other lightweith 'filler'. Then sand it down and spray paint it?

Will this be a working model? Ie are u gonna get motors / flaps/ etc!!

Flint

[Thaeris]

Sweet eggs and bacon, Herra! By far that is the best looking piece of carved foam I've seen in a very long time!

-Thaeris

[Herra Tohtori]

Thanks for the compliments.

Currently, it still lacks the ailerons, but after preliminary flight tests it seems that it has a ton of lift but I will need to position the center of gravity very carefully. Obviously, the original plane is rather tail-heavy and uses positive rudder angle in normal flight, but that is not possible for a glider. Neutral lift from elevators would be ideal, in which case the plane would pretty much stay on the glide path at all speeds. However, I'll probably be going for negative lift configuration which will make the plane's nose lift slightly when it's speed increases, which increases the angle of attack and reduces air speed.

Also, it seems I might have to replace the nose cone with something a bit more durable - after those preliminary flight tests today, it's somewhat banged and shortened. My thoughts are on cork, some light wood or reinforcing the styrofoam sufficiently with toothpicks and glue.


As for glue, I'm using water soluble glue called "Eri Keeper" which doesn't eat styrofoam. Unfortunately, I haven't got any way at the moment to smooth out the surface of the styrofoam to acceptable levels; I sanded it down to "mediocre" but ideally it would obviously be smooth and even; the large grain styrofoam is evil for this kind of stuff but for a zero budged plane (so far), I'm fairly happy with the results.

@jedimasterseth AKA Flint: No, this will not have remote control features or propulsion systems of any kind. First of all it's too small unless you buy really small servos, control rods and put propeller instead of dual ducted fans. Secondly, styrofoam is far too fragile to do that. If I carved enough room in it to put the batteries, engines and other electronics, it would get too heavy to fly and it's structural integrity would be rather dodgy I'll wager. If I had the money to dump on at least four-channel radio, speed controller, two good ducted fan units, batteries and good quality hobby foam and carbon fibre reinforcements, then I would build a remote controlled plane.

It will have ailerons (which will double as flaps if I want to use slow flight configuration), rudders and elevators, but I'm going to leave the leading edge slats out, mainly because I need to reinforce the leading edges of the wings somehow and if I put slats on them they will never stay put more than one flight and I don't want that. The control surfaces will be used exclusively for trim purposes to achieve different flight profiles, for example getting it to fly straight and level, or do a loop when thrown faster and up, then settle for straight and level flight, or make a wide right hand turn that will lead the plane back to the pilot.

It would be interesting as hell to build an RC plane though...  Maybe some day. Foam is a nice material to work with though. Much easier to work with than wood.

Although I have to say cardboard and normal paper still take the cake for the price and attainability for airplane materials. Paper airplanes are cool...

[lostllama]

Nice work. I really like the look of the Flanker (and the MiG-29).

Incidentally, I visited an RC model airshow about a week and a half ago and took some photos. This model of an Su-34 was on display. I think it uses an electric fan for propulsion.

I can post up pics of other models (some are of large scale models) if anyone is interested - quite a variety were flying on the day. I could start a thread about it.

[bizzybody]

Very cool. There are RC planes much smaller than what you've carved out. google for combat gliders. They're mostly built really cheap, often from various types of foam then covered with glass fiber reinforced tape, called strap tape in the USA.

The object of combat gliders is to launch them into the air then make them smash into each other. Whomever is still flying last wins! It's like an airborne demolition derby.

A quick and dirty hot wire foam cutter can be built from a piece of nichrome wire, a coping saw frame, a 6 volt lantern battery, a rheostat and something to hold the wire in the saw frame while insulating it electrically from the frame.

Something like that will cut any foam as smooth as it can be cut.

Urethane resins and glues won't eat polystyrene foams and plastics. Nor will epoxies. Polyester resin will eat polystyrene foam just like Alien(TM) acid blood ate through the ship decks in that movie. (I figure they painted some foam then dribbled gasoline or acetone on it.)

Aluminum tape (flue tape) isn't that expensive. It's used for sealing heating ducts (which duct tape is the worst thing for) and vent flues for gas dryers, stoves and water heaters. It's also used for sealing the joints in double foil faced foam board used for insulating houses. (Which also turns a house into a fair approximation of a Faraday Cage when the house also has a metal roof.)