DIY Catapult for safe launching of RC Models

[@get2zero]

Simple, portable, and effective! I'm building a copy!

[@michaelghammer]

🙂👍 You will not regret it. It will save you so many models.

[@AlexAtYair]

Interesting design. I was thinking about a large bow, string and arrow, the bow string being a bungie stretched at right angles to the launch ramp using a flexible wooden bow. Model (arrow) hooked onto the bow string with a foot release. Advantage, more compact in use. No need to stretch a bungie across the field. But you do need a very strong bungie!

[@michaelghammer]

Sorry about the late answer. I don’t think that a bow and string will work. You want a pull that gradually tapers off. Not a pull that is like a kick. The bow and string would most likely rip the bungee hook right out of the model.

[@yairenergy]

@@michaelghammer Ok, thank you for the tip. I’m going next gen, so will report back when project is complete.

[@joymakerRC]

im so thankful for you , i needed this , ill build similar this season

[@michaelghammer]

I´m glad you found the video useful. A good catapult setup will save you a lot of models.

[@joymakerRC]

yeah , i have crashed 2 flite test p-38s that i built and a corsair. I have 2 A-10s a sea duck and a sea otter and f-18 that i dont want to crash. lol

[@ebg4614]

Awesome!!

[@AnHE-pu5cm]

wau, was sind das für Nurflügler ?

[@serryscs]

what model is that on 0:04? very cool plank design

[@michaelghammer]

Thanks. It´s my 200% size Wasp. The Wasp is no longer in production, but I still have a few that I fly on a regular basis. Here´s an old video of the original: kzbin.info/www/bejne/nKfLaa1_qc-Dr5I

[@ednadavestaples7254]

What size hardware is used in the launcher pedal?

[@ednadavestaples7254]

Ah, nevermind, I see that the info is on Thinginverse.

[@MarkSchaff]

Great video. Was wondering if anyone knows of 3D printing resource on-line? I can't seem to find anyplace local... Thanks - Happy New Year.

[@michaelghammer]

Hi Mark. You should get your own printer. It’s a fun learning experience and you will be surprised how many things you will end up printing. And you don’t have to buy an expensive new printer. My first printer, an Anet A8 ended up printing at least 15 RC models + a lot of other stuff before I sold it for half the purchase price. Replaced it with a used Artillery X1 Sidewinder. Great printer and very inexpensive. Go for it!

[@MarkSchaff]

@@michaelghammer hi! thanks for the response and something i'll take a look at. i bet there's a ton of things that I would find it useful for.

[@ArceezRC]

Hi, noticed that you launched a prop plane. How did you connect the planes hook so it doesnt get caught in a spinning prop?

[@michaelghammer]

Connection is the same as on the jets. The Y-connection and the gasoline tubing ensures that the bungee will disconnect and fall away cleanly. Only add throttle after the model is in the air and the bungee has stopped pulling.

[@ArceezRC]

@@michaelghammer thanks!

[@kudriy787]

​@@michaelghammerhello, do you mean gasoline tubing on the rails of the launcher?

[@michaelghammer]

@@kudriy787 No, the gasoline tubing is put on the nylon fishing wire to prevent it from wrapping around parts of the plane after launch. I learned this the hard way 😀

[@kudriy787]

@@michaelghammer okay, thank you very much for answer

[@ismailkalkan2383]

hello brother, I have a question, how do you find the pulling force with the scales,,,that is, how many times the weight of the plane you will fly should be, the weight you measured in the tire,,,I don't know if I can tell you,,my plane is 1kg,how much should I pull the tire,thank you for your answer in advance

[@michaelghammer]

Hi Ismael. You need 6-7 times the weight of your model as the pulling force of your bungee. So for your model at 1 kg your bungee should pull 7 kg.

[@ismailkalkan2383]

@@michaelghammer thank you very much my friend,,you have been very helpful,,greetings

[@solentlifeuk]

I had similar setup of trigger line to rear of rails - till I got it caught in a pusher prop. Even with the heavy ring to make it stay down - it still got caught. So I modified to have the trigger line fixed to a rail at front of ramp. The bungee line Y then went 1. to model as yours, 2. to a hinge pin at frono of ramp. The hinge pin being help UP by the trigger line. When trigger was pressed - the short line allowed hinge pin top fall forward - the bungee was then released to launch model. kzbin.info/www/bejne/pavQlZKXhbJ_mKc

[@michaelghammer]

Hi, Nice setup. However I think the setup with the hinge pin is a bit overengineered. But hey, overengineering can be fun, right? After I put gasoline rubber tubing on my strings near the model, I have never experienced any problems with the string or ring getting caught in a prop or tail.

[@solentlifeuk]

@@michaelghammer Yep - I went nigh on 10years with a 'heavy' trigger line until my pusher prop T45 got caught twice in one day ! I've now copied your rails - nice .. only modification was to hinge large ground pegs to rail ends so I don't 'forget' the legs ! I have mounted a release hinge system using a broken prop with hub ... onto a block that sits ahead of the rails without need to be fixed to rail frame. What I like as well as the simplicity of your rails - they can be moved closer or wider depending on model easily.

[@SeungyunaCho]

amazing launcher heeheheheheeheheh

[@hansleatherby1032]

Hi Michael Nearly finished building the Draken - great model I am also building the catapult - what is the diameter of your bungee?

[@michaelghammer]

Thanks Hans. I’m glad you like my Draken. The diameter of the bungee cord is approx. 10mm. But if you have thinner bungee cord, you can run two or three in parallel. You will need 6-7 kg pulling force for the Draken. Good luck with the maiden flight.

[@rmcarlsson]

Do you have link to where I can buy the bungy-line? Not sure what to search for.

[@michaelghammer]

Hi Mikael Biltema has elastiksnor. Or you can try Do It Yourself stores. I bought mine from a store that sells equipment for sailing yachts.