New four pulley compound slingshot

[JoergS]

Hello,

have been busy in the workshop today.

My newest creation is another compound slingshot, this time using four pulleys, of course all of them equipped with ball bearings.

This compound slingshot is really compact, because the rubber is stored very efficiently on two rollers per band. The slingshot is just 18 cm wide (7") and 15,5 cm (6") high, but it enhances the draw length by 17 cm per side! This means there is almost no more dead play in the action, my entire draw length is used effectively.

It shoots very good. I will do a video tomorrow including some action. Will be fun!

It looks a little bit like a candle holder - but I need to find a better name than that... ideas, anyone?

Jörg

 

[janobles14]

do the pulleys provide any mechanical advantage in this scenario or are they more of a space saving agent for longer bands? let us know the m/s or fps when you clock it! also how many joules that thing cranks out.

my vote for the name is "The Roller Rocket"

good stuff as always joerg!

 

[elmerfudd]

My guess would be that the pulleys do two things.
1) they allow for a longer draw. You can see that resistance would start at about only 3".
2) they likely increase the velocity somewhat by effectively shortening the bands as the projectile is launched. I think this would have the same effect as making the bands lighter, allowing more of their energy to be expended accelerating the projectile. I'm not sure on this though.

I also wonder about the efficiency of the pulleys. First off, it seems that any weight, friction or redirection of energy will result in some loss of energy. However, it also seems to me that the pulleys will have developed some momentum by the time the projectile is leaving the pouch and that that rotational momentum might help accelerate the projectile as well.

 

[BHP FAN]

I'll second janoble's ''Roller Rocket''.Great name for a great slinger.

 

[joshk-k]

The "Half-Menorah"

 

[The Highlander]

Very cool.

 

[War Squirrel]

The Fist of the Hebrew.