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UAV Catapult Launcher

Posted by Scott Ashcraft on March 6, 2013 at 7:38pm

Hello,

I am trying to design a catapult launcher for a ~20 lb UAV and was curious if anyone has designed and built one for a similar weight range. Based on my calculations, using a 70 ft/s final velocity over 12 feet at a 11 degree angle, I will need ~ 950 lbf after building in a 20% safety factor for friction within the system.

After looking into available designs on the market, it seems that for in this weight class the best launching methods use pneumatics. I have looked into numerous designs available on the market and one of the ones that stands out is the UAV Factory's pneumatic launcher (http://www.uavfactory.com/product/21). I have been trying to design one for my unique UAV design, but am hung up on the pneumatic design. I have not been able to find a pneumatic capable of providing this force with accelerations of 245 ft/sec^2.

Does anyone have any advice or personal experiences with catapults or catapult design that may be able to help in my case?
Thanks

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Replies

Sameer N Pujar January 4, 2017 at 10:28pm

how you made calculation for getting 950lbf of energy for 70ft/s final velocity over 12 feet at a 11degree angle
Richard Unwin March 20, 2013 at 1:51am

Hi I made one last year to launch my UAv and have had success launching a 60 size that weighs about 4 kg and has some power left which when I get back to it will be able to launch my bigger custom Uav. Total cost was about 300 with a bit of scrounging on eBay, the ram costing 110, and buying a unused gym machine for 100 got me a bunch of pulleys and steel to use. Search you tube for Diydrones launcher and you can see it in action.
Temperature or low temperatures are not a concern here in Australia, but if you can keep water out off the airlines and ram then I would not expect too many problems, unless you are talking well below freezing.

Regards richard
Richard March 8, 2013 at 8:46am

This may not be of much help, but I am currently in the process of building a catapult launcher for a 3kg flying wing.

I intend on using the same launcher to catapult my Homebuilt 5kg Twin Boom Uav which weighs about 11 lbs. It does take off from land but needs too much room and a flat surface. I am going to remove the wheels which will save weight and improve performance.

I am using this design - I am half way through building it, but it will easily take the weight of my 11 lb plane and more. The main rail is 50.8mm Alloy Box section with 3mm wall thickness. I am going to use a bungee and pulley system to get the tension.

I worked out i need 5 times the weight of the plane pulling on the bungee.

Good luck!