How To: Control Line Airplane

A control line airplane once completed if flown in a circle roughly 35ft away with just elevator controls. Two people stand in a small circle in a open area holding their control in one hand. One or more people will help start your engine and launch your plane. Attached to each plane will be a 5 foot streamer of which you will try and cut with your prop. The idea is to combat with the other flyer in the circle with you and cut their streamer as many times as possible to earn the most points!

Supplies:

Wood
o Variety of balsa wood sheets

o Plywood for firewall

▪ Tools o Sandpaper

o Exacto knife

o Cutting mat or something you can cut into

o Thick and thin CA glue

o High heat hair dryer

o Hot iron

o Model covering

o .049cc motor with motor mounts

o Small screws

o Pin drill

o Piano wire

o String and a handle for flying

o Paper Hinges

o Control Horn

o Bell Crank

o Scissors

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Step 1: The Wing

▪ Ribs- Cut from template or draw your own.

o Tear Drop shape. Ribs should be in elongated teardrop in shape if unable to find template. Larger part of tear faces forward for best lift.

▪ Tip: Make two of the ribs out of slightly thicker balsa. These will be the two inside ribs closest to the engine mount to provide sturdiness and strength.

▪ Sanding

o Pin all wing supports together aligned as best you can on all axis’. Sand into uniform shape; this will make the airfoil of the wing the same throughout.

▪ Wing

o Use long, thin, square, rectangular prism like balsa as your leading and trailing edges for ribs.

▪ Recommendation: I suggest that you drill one or two small holes in the still pinned together ribs. Then, put some sort of rod through both holes in order to keep them all aligned. This will help when gluing the leading and trailing edges on. It will make sure that all ribs are set at the same angle as well as make it easier to distance them appropriately.

Step 2: Bell Crank

- The Bell Crank is a plastic, triangular shaped elevator control part. It is the only moving part besides the elevator itself. Two wires are clamped to it and then run out one end of the wing for the control lines to attach to. The third hole is in between the two control lines and runs out to the control horn on the elevator. This is how the plane is controlled and how it stays flying.

o Between the middle two ribs insert a medium thick piece of balsa that bridges the gap and glue in.

▪ Use of gussets on opposite interior sides of this platform is not required but highly recommended

o Use pin drill to make hole for the bell crank to be secured on. Make sure not to tighten the bell-crank down too much, it needs to be able to move freely and easily.

▪ Before securing bell-crank: Line it up in place and take a ruler to find the path of travel that the control line wires will take. Make marks on top of each rib as place holders for where the holes will be drilled for those wires.

o Grab a thinner but not super flimsy piece of piano wire for your control lines. Cut a tad bit long in case you mess up on the bending the first time. Before securing the bell-crank, feed them from the tip of the wing back towards the middle of the wing. With the bell-crank free, it should be easier to attach the wires.

▪ Tip: when attaching and securing wires, make circle bends to allow free movement without interference with bell-crank itself.

o Once wires are attached, secure the bell-crank.

Step 3: Elevator Control and "Z" Bend

Elevator Control Lines

o Cut a thick piece of piano wire to span the gap from the control horn to the bell crank. o Insert straight end into the hole on bell crank with a screw predrilled to secure it.

▪ Z bend pliers

o Using Z bend pliers, make a bend at the opposite end of the wire in order to secure it to the control horn.

▪ Play with distance to make elevator perfectly level with wing in order to get the most throw in both directions.

(Note: special threaded wire is available at hobby shops that will allow you to simply twist to adjust the elevator throw. This will make it much easier to center it with respect to the control lines, otherwise it would just be trial and error.)

Step 4: Wing Tips

▪ Cut out triangle shaped piece of balsa to attach as wing tips

Step 5: Sheeting

▪ Take thin flat sheet of balsa and measure out enough for it to span at least 2 ribs.

o Does not need to cover entire wing

Step 6: Covering

▪ Use special plastic model covering to wrap the plane.

▪ Cut large enough piece to cover plane entirely.

▪ Tac down with high heat iron on all edges

▪ After fully ironed in place, use high heat blow drier to shrink wrap the model

Step 7: Elevator and Booms

▪ Shape Elevator

o Cut out any shape elevator preferred. Shape and size will not affect flight to drastically; however, this is within reason. Proportional for the size is recommended.

▪ Control horn - The control horn is the piece that the wire from the bell-crank will connect to in order to control the elevator.
o To install this piece, use pin drill to drill two holes in the elevator in line with the bell crank, then, simply push control horn into place and glue lightly. (see picture for further clarification)

▪ Booms – These are two thicker pieces of balsa cut to straddle and fit like one, overlapping with the wing. (See picture for better description)

o These will need to be congruent as well so sand them while pinned together.

o After attaching booms, cut horizontal slits with razor knife that are about a cm deep in both the booms and elevator. This will be where the paper hinges are inserted and then glued. (Note: the hinges I am referring to are not just paper like you would write on. They are a special type from a hobby shop.)

o Make sure that you cut the covering free in the spot you are planning on gluing your booms to; the glue will not stick to plastic

Step 8: Motor Mount

▪ Cut 5 thick pieces of balsa in the shape of the wings leading edge so motor mount can slide on front.

▪ Cover wing with thin balsa for structural stability

▪ Use plywood to make face of motor mount and glue onto leading pre-sheeted edge.

▪ Pilot the holes before screwing

{Note: Before attaching motor, you must add 'tow out' to the motor so it does not fly into the circle towards you. To do this, add 2-3 small washers under the motor on the screws that are closest to the actual control lines. You may also build this angle into your motor mount, either work great!}

▪ Attach motor with screws

Step 9:

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    4 Discussions

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    satakraudreyobscura

    Reply 4 days ago

    Thankyou for taking the time to look ! hope it was helpful!

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    Henmarsh

    6 weeks ago

    Nice instructable but a few points. Paper is not a suitable material for the elevator hinge especially if you're using a gas motor. Proper hinges are available from model shops or you can use thin plastic sheet (transparency printing film is good).
    It is useful to add side thrust to the motor to keep the lines taut. Angle the engine mount a few degrees towards the right wing (opposite the control lines).
    Use a firm/hard piece of balsa for the elevator and cover it before attaching it to the wing for a much better finish.
    Plastic elevator horns are available which mave fitting and adjusting the elevator easier. Pushrods with threaded ends are available which allow for adjustment of the elevator angles.
    Control line flying, especially combat, is great fun - enjoy!

    1 reply
    1
    None
    satakrHenmarsh

    Reply 4 days ago

    The paper hinges aren't actually paper like what you would write on. It is a special kind from a hobby shop that when you drop thin CA on them, they harden. After they harden you manually move the elevator up and down a couple times to sort of break them again so they can move. Since the glue cant actually set that well on polycarbonate materials like the hinges, the hinge just acts as a gateway for the CA to move into the model and elevator so it can hold the hinge in place. They are quick and easy, all you have to do it cut into the thin edge of each part and insert it.
    In this particular model, there actually is built in tow out in the engine mount it is probably just hard to see or I may have not said anything about it. Lately I have been using washers rather than making the motor mount at an angle because it is a bit easier. Using a ban saw to cut the angle in the motor mount and then gluing on the plywood works fine but making it uniform and just adding washers at the end works great as well.
    I used the plastic elevator horn but not the threaded push rods. Ill have to look into that because adjusting the levelness of the elevator can be quite annoying to get perfectly aligned when you have to keep loosening and tightening the bolt. That may save time, do you know if that is part of the control horn? because the elevator has z bends it would not be able to twist which is why I was wondering which part does twist in order to move the elevator?
    Thanks for the feedback!
    Cheers