Quote (Azrad @ Mar 18 2013 08:29pm)
so wait, how are you create the force for each shot? are you re-twisting the rope by turning that dowel in the foreground on the last picture, then moving the arm into firing position?
Or did you just twist the rope once when you built it, and now just move the arm into firing position each time?
The dowels are fixed after the initial twisting. You pull the arm back for each shot. We have yet to create a release mechanism, so for now it's just pull back and let go.
Quote (saber_x3 @ Mar 18 2013 09:26pm)
I'm pretty sure your 1 of the problem is the contact area.
it is way too small compared to your overall rope length
I'd choose a wider arm, which basically shortens your rope length
The force transfer becomes much more instantaneous? there is a larger delay and loss of efficiency the longer your rope is, something on those lines
look at this for example, the arm is much wider
Your rope's thickness / length ratio is too low
so, I'd thicken the rope.
Try to make sure the the tennis ball is released at an angle a little bit less than 45, I wouldn't go down to 40
The exact angle isn't something I can tell you, but I do know that you want the angle to be less than 45
One of the easiest thing to test is arm length
There is a definite optimal arm length , I'd assume it is much shorter than what you have it at with your current setup
To test, basically just place the tennis ball on different places of the arm
Can you add more to it? rofl, like just a bungee from the end of the arm to bottom of the base in parallel with the arm
Something I wanted to do was add a sort of bumper to the top of the frame (to adjust the stopping point of the arm, and the release point)
The arm is just something temporary. I wanted to use a 2x4 or 2x6, but thought it would weigh down the arm's movement too much and take away from the final force. Also worth noting: there's a bowl we attach to the arm to hold w/e is being thrown, it's just not in the pictures.
When you say thicken the rope, do you mean the actual rope thickness, or just try to get a larger bundle? I read somewhere that smaller rope thickness was better, but you need big bundles of rope. The problem is getting any more rope to fit through the holes in the base.
And I was sort of thinking the same thing, adding some bungee cords or springs just to add more force, but I'd like to just use rope if possible xD
Thanks for all the help though!