|
| My Catapult. |
| Click on any of the thumbnails below to see a full size version of the pics. I built the frame out of 1 X 4 pine as well as the legs and sled. Currently I am using 3/8th bungee for my launcher but hope to upgrade to about 1/2 inch surgical tubing to see if I can improve performance |
|
|
| I decided after having one of the young fellows at the field almost hack his leg up with a prop bite launching a plane for me, to build a catapult. The design I used, I found a few different ones and copied what I liked from each to suit what I had in the garage. I wish I remembered where I got the ideas from so i could credit them for this. Found the link, it was on scalecombat.com under the workshop section. |
 |
 |
 |
 |
| Here's a good look at the release mech as well as the rear pulleys for the bungee. You can also see the tensioner pulley here that allows me to adjust the thrust for the pla |
| Here we see the dolley and the hold backs for run up prior to launch, they lock up to the front of the wing holding the plane back via a rubber tube across the bottom of the Cat. |
| Here are the two forward pulleys and the stop bumpers. As soon as I find the right springs I'll probably replace these. A good view of the leg locks and pivot as well. |
| I tried to make it universal as well, that is what the upper wire framed holder is for. Just bend the wire to suit and away you go, hope it works. |
| Cocked, locked and ready to rock, plane is held securely ready to be run up to full rpm and step on the release. |
| Another view of same with a bit better idea how the hold backs work. |
| Here is the best part of this thing, notice the tubing through the frame at the bottom of the pic, that pushes the hold backs solidly against the wing. this allows full throt |
| All folded up and ready for transport to the filed on Sunday. Takes about 10 seconds to set up, just pull the leg locks lfit the front, install the leg locks and it's ready. |
| The rails are 3/4 I.D. EMT and I just bent some aluminum up for the release. It folds easily for transport and I made the measurments exactly to fit into my van. Shoulda used a tape though. It's about 6 feet by about 16 inches. |
 |
 |
 |
 |
|
|
| As soon as the dolley moves forward the force of the bungee keeps the plane in it and the supports are free to fall forward and away. |