What is the most efficient projectile launcher?

[jimmyjj]

What is the most efficient projectile launcher?

[jim_mich]

For other people who are metrically challenged like myself, a 1200 mm circumference wheel calculates out to be about 15 inches diameter.

[getterdone]

Hi Jim, I can be metricly challenged to, but I think that 1200mm= 120cm
30cm =1ft , so 1200mm would equal 4 feet.

[jim_mich]

You are right.

And 48 inches circumference divided by Pi equals about 15 inches diameter.

[murilo]

One inch is equivalent to 25,4mm...

[jimmyjj]

nm

[justsomeone]

What did Jim say that was so offensive?

[jim_mich]

Jim your an arsehole!

And what did I say that offended you?

Don't pick on the metrically challenged!

[FunWithGravity2]

What is the most efficient projectile launcher?

anything that imparts the most efficient transfer of momentum from the energy giving device. It would all depend on your projectile and what you wanted that projectile to do, go long distance or punch through a wall ten feet away.

Pumkin chuckers that use air use it in the same way as a rifle would work, they try and accelerate over a longer period of time to get a small projectile to go a long way.

Cannons/ trebuchets focused on launching a larger mass a shorter distance (not always)

Will your energy come as a quick sharp punch or a longer gradual type?

Are you launching a small mass with a large energy input or a large mass with a small energy input?


Whats an ARSE :) i think i might be one?



Dave

[jimmyjj]

Jim i just felt that all this discussion on inches was irrelevant to the discussion and that in a way you were making fun of me especially by dividing by pi. I was not picking on the metrically challenged but rather felt that i was being picked on by the imperialists!

Fun with gravity i am lifting a mass of say one and a half ounces roughly four feet with a "quick sharp punch" .

I was thinking of using a coil spring but do not think this would be efficient as energy would be lost due to friction between the spring and the housing. in my case perhaps a leaf spring would lose less energy.

I am launching a mass with the energy stored from the falling of masses.

An arse is someone who gives cheek. Then again it could mean your lucky, maybe..... you arsed it ;)

[jim_mich]

Dang!

If anything I was picking on GetterDone. His posting seemed to say that your wheel would be 4 feet; but he didn't actually say 4 ft diameter; but that seemed to be his meaning.

So I was just trying to very politely state why a 1200mm circumference wheel (mentioned by JimmyJJ) would be only 15 inches diameter, and not 48 inches.

Fun with gravity i am lifting a mass of say one and a half ounces roughly four feet with a "quick sharp punch" .

This may be why your angry at me and why you erased your first posting? Is your wheel 4 foot diameter, which would make it about 1219.2 mm diameter instead of the 1200 mm circumference as in your first posting?

[rlortie]

Hi Jim, I can be metricly challenged to, but I think that 1200mm= 120cm
30cm =1ft , so 1200mm would equal 4 feet.

3.936996 feet or 47.24395 inches to be more specific.

Which is the circumference of a a circle = to 15-3/32" give or take a 1/64" in diameter, it will contain approx. 177.73 square inches.

Now all you regulars out there no I hate math, so how did I come up with these figures? I used the converter that we were made aware of by a now forgotten named member.

Its free and you can stick on your desktop for easy access.

http://joshmadison.com/software/convert-for-windows/

Ralph

[FunWithGravity2]

Jimmy
Just my 2 cents,

But a quick punch may need a little assistance, unless you have additional energy in the spring/bow from some additional energy source you may not find enough oomph to shoot you projectile up to where it came. If you want to use springs or some other energy storage device i would recommend that you employ some type of acceleration help when launching your projectile. Maybe a modified Jai Alai type launcher where you transfer your stored energy from the spring into that to launch your projectile. I would try and harness CF and Downward force of gravity to help your projectile gain additional momentum in the launcher and you just may shoot it higher than when it started.

Any experimentation should be done in a rotating reference frame, FWIW.



Dave

[nicbordeaux]

What is the most efficient projectile launcher?

jimmyjj, if I remember right your first post mentionned the compound bow. Wikipedia will give you reference to 80% efficiency, some maker claiming 99% effciency. Your issue here is that the force required to draw to "x" lb (0.453 grammes) is done over a short distance, you need a mighty kick/push. Still, it's an idea been discussed here before, there is probably some use for it but you'll need to make you own blade/cam/strings setup tuned for a particular purpose / power delivery (input). From experience I'd say forget bungee straps, springs are pretty inefficient for the application you are discussing (you want a differential between compression/release)... so probably the compound bow setup/principle would be your best bet. Unless you look at rotation :)

[FunWithGravity]

The Bow or the leaf spring would be my favorites for energy storage or energy redirection depending upon your point of view. In my understanding of things i think they are non linear, But what do i know. I'm probably wrong.


Dave