Storm the Castle B

[JSGandora]

Hmm, that seems a little on the unintuitive side. I have another question, what is mathematical relationship between the angle at which the finger (the piece in which the ring is placed through) is jutting out and the angle at which the projectile is released? I know that the greater the angle in which the finger is jutting out, the greater the angle of release, but what is the actual relationship?

[JSGandora]

That would be the almighty "Energy Rule", or more specifically 3.f

The device, without the counterweight and projectile, must not contribute energy to the launch. Example violations include: the axis upon which the firing arm rotates drops during launch, the center of gravity of the unloaded device drops during a launch motion, the triggering process provides momentum to the launch, a form of potential energy (compressed or stretched elastic solids, compressed air, etc.) is used. Without a counterweight and projectile, the launch arm must not make a launch motion when released from any position before the point where the projectile is released. Allowable types of devices include, but are not limited to, counterweight and floating-arm trebuchets, subject to these rules.

What you just asked about is highly illegal in this event.

Would a CW holder contribute to the weight of the CW thus violating the energy rule? What's the rule about the CW holder? I don't want to make one that violates the rules.

[wlsguy]

Hmm, that seems a little on the unintuitive side. I have another question, what is mathematical relationship between the angle at which the finger (the piece in which the ring is placed through) is jutting out and the angle at which the projectile is released? I know that the greater the angle in which the finger is jutting out, the greater the angle of release, but what is the actual relationship?

First, to answer your question about adding a little weight to the ring at the end of sling line. Starpug is correct. The sling will function correctly when the force on the ring pulls it off of the pin.
This can be adjusted by
1) changing the angle of the pin. You will want to be able to do this to maximize range. The best angle will be different based on projectile and counterweight combination.
2) changing the length of the pin. Hard to change in the 5 minutes you are allowed. find one and stick with it
3) changing of friction of the pin to the ring. Not much can be done to make metal on metal any better
4) changing the force of the ring. This is where adding a little weight helps. It adds to the force and makes the ring come off better

To answer your question about finger (pin) angle relationship. This one is harder because it changes as the counterweight increases. The best advice is to shoot your machine and start adjusting the pin angle (it is adjustable right?:)
When you want to lower the tractory (because the ball comes off too high) push the pin forward (toward the direction of the rotation of the arm) a few (3~5) degrees. If it is shooting too flat, push it backward a few degrees. If you have an adjustable pin, you will get the feel of how far to go.

Finally about counterweight holders. The best is to use a simple loop or ring for the counterweight. My minitreb photos in the gallery use a wire tie. You can also use an eye bolt.
I would not recommend making a platform. It is likely to be heavy and force you to add weight to the throwing side of the arm (so you don't break the energy rule) which will greatly reduce your range.

[starpug]

Hmm, that seems a little on the unintuitive side. I have another question, what is mathematical relationship between the angle at which the finger (the piece in which the ring is placed through) is jutting out and the angle at which the projectile is released? I know that the greater the angle in which the finger is jutting out, the greater the angle of release, but what is the actual relationship?

I don't think there's a cut and dry mathematical relationship, you just need to play with different angles and see what gets you the most distance. The magic measurement for me when I did the event was 15 degrees a believe.

That would be the almighty "Energy Rule", or more specifically 3.f

The device, without the counterweight and projectile, must not contribute energy to the launch. Example violations include: the axis upon which the firing arm rotates drops during launch, the center of gravity of the unloaded device drops during a launch motion, the triggering process provides momentum to the launch, a form of potential energy (compressed or stretched elastic solids, compressed air, etc.) is used. Without a counterweight and projectile, the launch arm must not make a launch motion when released from any position before the point where the projectile is released. Allowable types of devices include, but are not limited to, counterweight and floating-arm trebuchets, subject to these rules.

What you just asked about is highly illegal in this event.

Would a CW holder contribute to the weight of the CW thus violating the energy rule? What's the rule about the CW holder? I don't want to make one that violates the rules.

If the addition of the CW holder causes the arm to go through the launching motion even without the CW then yes. Someone posted a link which explains the energy well very well, you should look for it in the thread.

[JSGandora]

Okay, thanks! I have one last question, do you think a prototype would be good to build before building the actual trebuchet?

[starpug]

Okay, thanks! I have one last question, do you think a prototype would be good to build before building the actual trebuchet?

At this point in the end of January, no...

[brobo]

Okay, thanks! I have one last question, do you think a prototype would be good to build before building the actual trebuchet?

I've actually built about three trebuchets by now... instead of building a prototype I would build a "first draft" and test it and stuff, then modify it, replace parts, etc.

[brobo]

Sorry for the double post, but I'm having a bit of a problem right now.

Our trebuchet arm is really good. It's going through the motions with nice speed, but our sling isn't so awesome. No matter what we do, it always opens late and the projectile just sort of falls out. We can't figure how to make it open sooner! We've tried all different nail sizes, all different angles, even moving where and how the sling is attached. What are people doing with their slings to make them open at the right time?

[starpug]

Sorry for the double post, but I'm having a bit of a problem right now.

Our trebuchet arm is really good. It's going through the motions with nice speed, but our sling isn't so awesome. No matter what we do, it always opens late and the projectile just sort of falls out. We can't figure how to make it open sooner! We've tried all different nail sizes, all different angles, even moving where and how the sling is attached. What are people doing with their slings to make them open at the right time?

How much of a head does your nail have? I'm assuming it's one of those ones that is basically just straight. Perhaps you should weight it more? Maybe some Silicone spray would help... If none of those works could you post a picture perhaps of your nail and ring.

[crazycow2000]

I would like to thank everyone in advance for helping me. I would like to ask if anybody has any possible ideas for what I could do for the differing weight for the projectile. The projectiles have to be in 20-60 range, therefore I want to test a 20,30,40,50, and 60 gram options. I know that a racquetball will work for the 40 gram option. A tennis ball is around 60 grams so that works for that. But I have no idea what to do for the 20, 30, and 50 options, can anybody help me? Thank you