Tower Launcher

When we launch hobby planes (especially gliders) we usually have a deficit of initial height. For a free-flying gliders such problem causes the significant reduction of flying distance. So the best place for gliders launching is a hill with a sloping relief . This project gives ability to have your own "hill" in any flat terrain. Test handmade TOWER LAUNCHER.

Materials:

• wooden rod (L=3 m, 30x40mm) - 1 item;
• wooden bar (40x40x450mm) - 1 item;
• wooden bar (50x10x80mm) - 2 items;
• wooden bar (80x10x130mm) - 1 item;
• wooden stick (D=10mm, L=180mm) - 2 items;
• metal wire (D=2mm, L=1000mm) - 1 item;
• metal corner-bracket (20x20mm) - 2 items;
• elastic band for clothing (1000mm) - 1 item;
• ballpoint pen with a rod - 1 item;
• plastic ring (D=10mm) - 1 item;
• paperclip - 1 item;
• rail clamp (small washer) - 1 item;
• any rope (L=4 m) - 1 item;
• set of screws;
• paper plane.

Tools:

• hacksaw
• office knife;
• scissors;
• sandpaper (file or rasp);
• drill with a set of drill bits;
• awl;
• pliers;
• screwdriver;
• ruler;
• pencil.

Construction is very simple: crossbow launcher mounted on the tall rod with a distance starting mechanism. Details - on a technical drawing. You can change dimensions use another materials but in a next steps we will talk about only one variant of realization.

The BASE of our crossbow-construction is wooden bar with a length up to 0.5m. First of all we need to mount BACK support on the BASE part. Don't forget to make throughout hole (diameter 4..5mm) near the back side of the BASE part – LOCKING ROD will pass there.

Mount the LOCKING CHANNEL (made of ballpoint pen body) on the front side of the BACK part. You can use hole on the BASE part and LOCKING ROD (ballpoint pen rod) to get a correct position of a LOCKING CHANNEL.

Because we make a crossbow (in fact) we need to prepare two SIDE RODS (length about 0.15..0.2m) and SIDE BRACKETS for them.

Mount the ready SIDE BRACKETS on the BASE part (at a distance about 0.3m from the BACK part).

You need to organize a correct motion of the AIRPLANE/GLIDER from the crossbow. So make a simple RAIL using metal wire. Mount the RAIL using two halls on the front side of the BACK support and simple RAIL HOLDER (any washer D~10..15mm) on the top side of the BASE element.

Make the LOCKING RING (using paperclip) and put it on the ELASTIC BAND. Then mount the ELASTIC BAND on the tops of each SIDE RODS.

To prevent fall down the AIRPLANE (before start) make a simple AIRPLANE HOLDER (using any plastic cover). Then mount it on the top side of the BACK support. So the elastic edge of the HOLDER will fix the back side of AIRPLANE wings.

The main stage – find appropriate TOWER ROD (about 3m or higher). Then fix the crossbow on the top the TOWER ROD using two CORNER BRACKETS.

Make the LOCKING ROD using ballpoint pen rod. Make connection between the LOCKING ROD and STARTING ROPE (length about 2m).

Pull the ELASTIC BAND to the SUPPORT part, put the LOCKING ROD throughout the hole in the BASE and LOCKING CHANNEL, finally put the LOCKING ROD throughout the LOCKING RING (on the ELASTIC BAND).

Put the AIRPLANE/GLIDER on the RAIL and move it under the AIRPLANE HOLDER (near the locking mechanism).

Install the TOWER ROD (with crossbow and airplane) on a start position. Take the STARTING ROPE in your hand and wait for a lucky moment.

Pull sharply the STARTING ROPE and see a start of your AIRPLANE/GLIDER.

Lets also remember the general design of TOWER LAUNCHER.

A few words about the AIRPLANE/GLIDER. Certainly you can use the simplest paper variant of a glider but I can recommend to increase its strength using bamboo stick (fix it on the bottom of your model with a bit of glue). According to such variant It also need to increase the wings area.