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Golf ball Launcher w/ compound bow... HELP!!!

Posted: Fri Dec 04, 2009 6:54 pm
by mysticjbyrd
I have an old compound bow, and I decided to use it for a golf ball competition. The bow and arrow is pulled back, and held by a release at a given point. The arrow is released and basically pushes the ball through a metal tube that is only slightly larger than the ball.


I am needing to hit a target at 50 yards. Unfortunately, I am only getting 45 yards with an angle of 45 ish degrees. The bow is already set to max on the pulleys.

The bow is old and I could replace the string or something, but I seriously doubt that this would help as the force comes from the bow. Anyways, any tips or even an idea would be great, thanks.

Competition is on Tuesday and I need 5 more yards and maybe more. Heck if I have to shoot into the wind as it stands, then I will be royally screwed.

PS: Upgrading the bow is not really an option, and its too late to design a new project.

Posted: Fri Dec 04, 2009 7:06 pm
by mysticjbyrd
So far I am thinking,

Shorten barrel
Shorten arrow
Lightly lubricate barrel
Lubricate the pulley of bow
Overextend the draw of the bow.
Make a stronger frame to set my bow on and hopefully reduce energy lost to vibration.

Posted: Fri Dec 04, 2009 7:28 pm
by tghhs
just build a simple sprinkler valve cannon.

Posted: Fri Dec 04, 2009 8:11 pm
by bradisfun
yeah i agree just build a simple in-line moded sprinkler valve canon and if your really want this thing to go then get a 2" sprinkler valve from ebay for like 70 bucks (tho it might not come in time

Posted: Fri Dec 04, 2009 8:17 pm
by mysticjbyrd
I cant build an air cannon because I have already done extensive work on inventor drawings and a finalized report.

There is absolutely no way I could build another project, draw it, and make up a report in the remaining time. Especially considering it is near the end of the semester with finals coming up.

Posted: Fri Dec 04, 2009 8:42 pm
by bradisfun
OK OK i might have and idea........... just get some sort of thin sheet metal like tin or something and stick behind the bow part (the flexibale part, forgot what this is called cos don't do archry any more) and scru it in

this should work
i did this once with a old bow cos it was the only bow at my farm and i was bord so try this but i have to go will be back in like 30 min

Posted: Fri Dec 04, 2009 8:50 pm
by jackssmirkingrevenge

Posted: Fri Dec 04, 2009 8:56 pm
by mysticjbyrd
bradisfun wrote:OK OK i might have and idea........... just get some sort of thin sheet metal like tin or something and stick behind the bow part (the flexibale part, forgot what this is called cos don't do archry any more) and scru it in

this should work
i did this once with a old bow cos it was the only bow at my farm and i was bord so try this but i have to go will be back in like 30 min
I like this idea, but I am worried it would weaken my old bow too much.. And if it did not work, then it could possibly make it worse.

Ok ok... How about instead of drilling holes in it... I could maybe use fiberglass.

Posted: Fri Dec 04, 2009 8:59 pm
by kotabuuki1
Yea those airguns are cool, but rather overpriced.

have you tried shortening the arrow and lengthening the draw?

Posted: Fri Dec 04, 2009 9:09 pm
by mysticjbyrd
I believe the bow is at max draw... I did think about just forcing it past that, but again it is old and I do not want to over do it.

My teammate is in the process of shortening the arrows tonight.

Posted: Fri Dec 04, 2009 9:09 pm
by jackssmirkingrevenge

Posted: Fri Dec 04, 2009 9:24 pm
by bradisfun
yes u could def's use fiberglass that would be an easy soultion but it mite take a while
oh and when adding stuff to the bow allways add it the the back so that it is being compressed not puled apart cos this dosent work just wastst time( trust me i no)

Posted: Fri Dec 04, 2009 9:32 pm
by mysticjbyrd
What if I cut the barrel in half? The arrow might be flexing and hitting the walls of the pipe....

So what if I cut a pipe, any pipe will do, in half and tried that? I am afraid that the arrow might not stay on the ball though.


On the other hand, I do not know the maximum amount an arrow will flex... So it is possible that this will accomplish nothing. Anyone know where you would find an arrows maximum deflection?

Posted: Fri Dec 04, 2009 9:34 pm
by mysticjbyrd
bradisfun wrote:yes u could def's use fiberglass that would be an easy soultion but it mite take a while
oh and when adding stuff to the bow allways add it the the back so that it is being compressed not puled apart cos this dosent work just wastst time( trust me i no)
When you say the back, you mean the side with the string, right?

Posted: Fri Dec 04, 2009 9:36 pm
by bradisfun
yep, the side facing u when u fire it
also it would help if we could see some pics

hey replaceing the string would do a bit but i'm not shure how much
i didn't ever really use a compound bow (i did u se 1 just i didn't own 1) but i'm pritty shure that the string is the main sorse of power and thats y the lbs is much lower than a regualer bow , but i'm not shure u could problay google it or sherch "how doe's a compound bow work" on youtube