Building a Spring Launcher for Firing Projectiles

[Typesylvester]

I need some ideas on how to build a launcher which will fire a spring (about the size of a pinky) over a distance of about 4 metres. The launcher has to be capable of firing a spring from any angle above the horizontal (0 to 90 degrees) and the target will be at ground level.

I think a simple and cheap, but effective design, will be the best for this project. Thanks in advance.

 

[Danger]

Welcome to PF. You could always just let the spring launch itself. Compress it inside a tube with a retainer like a grenade pin to hold it down. When you pull the pin, it should come flying out.

 

[Typesylvester]

Welcome to PF. You could always just let the spring launch itself. Compress it inside a tube with a retainer like a grenade pin to hold it down. When you pull the pin, it should come flying out.

Yes, I think launching the spring is what needs to be done. I was thinking of stretching the spring with the tip of a pencil/pen/compass, etc on a ramp inclined at a particular angle. Then once I stretched it to the length that is required I would simply lift my pencil/pen/compass, etc... and it will fly of the ramp as a projectile. But the problem is ... what will hold down the spring at the tip of the ramp to allow the stretching to occur? ...whatever it is cannot interfere with the movement of the projectile when it immediately begins to fly off.

 

[Danger]

The easiest way would be to just straighten on end of the spring into a 'leg' and simply hang it over the end of the ramp. That depends upon the strength of the metal, though.

 

[Typesylvester]

The easiest way would be to just straighten on end of the spring into a 'leg' and simply hang it over the end of the ramp. That depends upon the strength of the metal, though.

I see. Do you have any ideas on how to design the launcher so that the ramp can point at any angle between 0 to 90 degrees above the horizontal?

 

[Danger]

I'd just hinge one board to another, using one as the base. Even a piece of duct tape would suffice if you don't want to buy a real hinge. Then insert something between them, such as an eraser (something non-skid) to wedge the assembly open at the angle that you want.

 

[Typesylvester]

One more question. If the projectile launcher is on a desk, and the spring must fall 4 m horizontally from the bottom of the desk (1.0 m) high, how do I find 3 different launch angles?

 

[Danger]

There's not enough information available to calculate that (and I couldn't calculate it anyhow). Trial and error would be my approach.