Hello,
I show you my pneumatic launcher for my skywalker X8.
Why a pneumatic launcher ? Because I think it's a funniest idea than a bungee launcher et technically more interesting.
It's works like the mini uav launcher system.
Air tank -> QEV -> air cylinder -> pulley -> trolley -> airplane
A 12V pump pressure the air tank with a lipo battery in few minutes.
The launch thanks to a pedal which start QEV.
All part are homemade with my mill machine
Cédric Siou
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We have made a tool for sizing UAV pneumatic catapults. You can learn the maths and modeling behind it here
https://www.researchgate.net/publication/315000832_Computer_Aided_M...
@Ced,
The force exerted on the piston is Piston area X atmospheric pressure. There are limitations to this approach - with a pneumatics ( compressed air) based system, you can increase the force on the piston by increasing the air pressure - a vacuum based system has only atmospheric pressure available and so the only variable is the piston area. The advantage is a constant force and acceleration, with predictable and constant loads experienced by the airframe.
Nampilot
#Nampilot
Ok, how do you calculate the force of the piston ?
Ced
Hi Ced,
It is quite a simple concept - the piston in the tube is connected to the cable which protrudes out of the end of the tube - this is then attached to a cable winch ( no compressor/vacuum pump) and the winch simply pulls the piston back in the tube. This creates the pull vacuum on the other side of the piston. The cable then links to the carriage, and is released from the winch at instance of launch, and away it goes..
Nampilot
#Nampilot
Nice launcher, if you have more details on your design I do not mind.
Thank's
I like it. Now you can put it on a boat and have a mini carrier.
Looks great!
Here is a small pic of a large launcher I designed - it uses vacuum rather than pressure. Much more predictable and constant acceleration. Also, if the piston is allowed to stop some distance from the start off the vacuum cylinder, it actually begins to build positive pressure and creates a gentle deceleration for the carriage - no hard bump stops...
In the picture, the 'cylinder' is 14meters long and 800mm diameter - a wound composite cylinder... The UAV weighs 155kg
Nampilot
First thank you for you comment,
Like you can see on the picture there is a reduction which limit the rate of flow.
The cylinder has a 32 mm bore and 900mm length with G1/8 pneumatic connection.
The theoretical force at 6 bar (for launch X8 I put 6.5 bar inside the air tank) it's 483 N, with the pulley system it's decrease to 483/2 = 241.5 N, the weight of the X8 it's between 35 and 40 N.
So, for increase the power of system (the trolleys speed) I have to modify the intake air of cylinder, but it's not easy with a 32 mm bore cylinder, the best way it's to do a homemade cylinder or I can take a bigger cylinder like 100 mm bore and shortest but I need more pulley for launch on the same length.
Each launching, the air tank lose about 0.5 bar, so I start the pump few second for reach the initial pressure.
I Haven't weigh the launcher yet but I think about 25 kg without air tank. In next video I show you how I assembly the catapult.
Yes I'm based on military launcher
What is the piston size and stroke? Weight? Launches per tank? Air pressure? Very nice launcher. I think I have seen a similar looking military model, did you base it on that?
Very well done!
When do you start work on the pneumatic lander? :^)
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