SpudFiles

Hi, i have an RC plane and I want to do this:

My plane wheight is 1.5kg and I need to fly at first between 70 to 100 Km/h (the wings are small and it is a speed model really hard to launch by hand)

Do you have any idea about that. I know that I need the bottle but i don't know what type of valve i can use or the system to activate the launch. Do I need a separate tank at the base to lower the pressure?

I want to test several pressure before put my plane inside.

Thanks

There is going to be a few different factors to consider here. Mainly the construction of the plane. Will it handle the sudden forces all at once? That's how these spud launchers work. Give some details and we can better help you.

Would this work

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that "piston setup" seem like a better idea than stuffing it in the barrel, the extra weight of the piston would stabilize the acceleration. not to mention you'd still have a decent spudgun when you're finished

Unnecessary complication, unless you like to complicate - vary - experiment With a rubber system, conveniently designed, you can shoot any model aircraft
Watch this. The aircraft has a mass of 7.5 kg
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What does your plane look like? If you want good advice it's critical to know the size and configuration.

Tangentially related, we had discussed tube launched aircraft briefly in this thread a while back.

So the plane is like a rocket with a foldable wing (turn from 0° to 90°). I want to launch it from a tube which is also the tube to transport it.

Mass: 1.3 kg
I need to have a speed after launch which is 70km/h because the minimum speed is 65 km/h. After I have actually 1.7kg of thrust on the propeller so it will be enough. I am designing modification for the foldable launch.

The goal of the project is to have a quick set up on the field and a reliable launch system to focus my research on the propulsion system and wing airfoil to have the best speed.

Actually I thing that my new design will fit in a 70mm tube launch but 100mm can be good with a faom reduction inside (it will fall after launch).

I want to do a prototype with pvc pipes but the final design will be machined i think.

I modeled a launcher for you using GGDT.
I used a 4 inch diameter barrel and 2 inch diameter chamber with a modified one inch sprinkler valve between them.

Using only 125 psi of air and a 15 inch long barrel, and assuming a 200 gram foam sabot for your 1300 gram aircraft, we get a launch velocity of approximately 70 km/h.

I'm assuming you're in France so you'd have to find metric equivalents.

The chamber is relatively small so 125 psi can be reached with a good track pump or if you don't feel like pumping, a paintball bottle with a regulator or a good automotive compressor (avoid the cheap Chinese ones, they struggle even up to 40 psi...) will do the job.

While it gives you the performance you want, note that this configuration is not ideal because the valve is rather small. The best would be to find a bigger one, this will allow you to use lower pressure and a longer barrel, giving more gentle acceleration to the aircraft and making it less likely to be damaged on launch.

Thanks this is a really good answer i didn't know the GGDT! I am going to study this.

Do you think that I ca use Paintball accessories to do it? A bottle, a regulator to fill the chamber and a trigger system ? Like that I have just to do the chamber and the cannon

Or with an electovanne (solenoid )like rc retract train systems? Peurhaps a better one. I could launch it with my phone with an app. It could be funny and easy to do

Phil wrote:Do you think that I ca use Paintball accessories to do it? A bottle, a regulator to fill the chamber and a trigger system ? Like that I have just to do the chamber and the cannon

Paintball is geared towards valves with relatively low flow and high pressure, what you want in this case is low pressure and high flow. It is practical to use a low pressure regulator on a paintball bottle to fill the chamber but not much else.

Or with an electovanne (solenoid )like rc retract train systems? Peurhaps a better one. I could launch it with my phone with an app. It could be funny and easy to do

It would be unnecessarily complicated to use a servo but the sprinkler valve I showed you could be actuated by a solenoid valve instead of manually.