Punkin' Chunkin'

[Bob Thompson]

I've been trying to contact the governing body of the punkin chunkin event and I'm not getting any reply.
I would like to see if they have an open or demonstration class for non-traditional launchers. I know they eschew explosive powered launchers including flammable gas type, and I'm not suggesting that they allow them. I would like to scale up my E-mag linear accelerator or "rail-gun" for launching punkins. I'm not sure it's even feasible but it sounds like it would be fun to try.
I just don't want to invest that kind of time and effort and not have a venue for exhibition.

Does anyone here have any insight with this organization?

[Gordon Maney]

You've been drinking again, haven't you?

[Desoto61]

I know they do have an exibition class that is more open but you're limited in other ways. I don't think you'd be able to be added into any other class. IIRC you can't use a sebo to launch the pumpkin.
At the national they don't have time for any special demonstrations, but there are other competitions.

[Bob Thompson]

You've been drinking again, haven't you?

No Gordon, I come up with this kind of lunacy stone cold sober. You wouldn't believe what I might conjur up pie-eyed. ;-)

[Bob Thompson]

I know they do have an exibition class that is more open but you're limited in other ways. I don't think you'd be able to be added into any other class. IIRC you can't use a sebo to launch the pumpkin.
At the national they don't have time for any special demonstrations, but there are other competitions.

Okay,you're using acronyms I'm not familiar with, specifically IIRC and SEBO.
Would you be so kind as to elaborate. I'm guessing IIRC has something to do with "Rules Comittee" but I'm stumped on SEBO.

It would of course need to be mounted on a Power Wagon though.

[Desoto61]

Okay,you're using acronyms I'm not familiar with, specifically IIRC and SEBO.
Would you be so kind as to elaborate. I'm guessing IIRC has something to do with "Rules Comittee" but I'm stumped on SEBO.

It would of course need to be mounted on a Power Wagon though.

IIRC - If I Remember Correctly

I was typing on my phone so I took the shortcut.

Sebo - I guessed at the spelling on this one, I meant sabot.

http://en.wikipedia.org/wiki/Sabots
The only thing that can leave the weapon on a competition machine is the pumpkin.

[Bob Thompson]

IIRC - If I Remember Correctly

I was typing on my phone so I took the shortcut.

Sebo - I guessed at the spelling on this one, I meant sabot.

http://en.wikipedia.org/wiki/Sabots
The only thing that can leave the weapon on a competition machine is the pumpkin.

Okay, that makes sense. I don't do a lot of texting so I'm not up on the shortcuts. I was a bit foxxed by sebo but if you meant sabot then I'm on board.
I had noted in the rules, that no part of the machine may cross the firing line but it's moot since I have no plans in that direction. The unit I used to launch oranges had a ferrous plate on a track of UHMW poly. http://en.wikipedia.org/wiki/Ultra-h...t_polyethylene
The cradle never leaves the track. I use resistance braking to slow the cradle down before it hits the stops.
There are some definite drawbacks to having a bunch of high gauss coils firing in sequence. Shielding would be a must to prevent killing communications equipment, ignition systems and various other EM sensitive gear.
I don't know what power consumption would be either, but that's just math.
I built my first rail gun in the 80's because someone sent me plans for the electronic bits. It fired ball bearings at an amazing velocity but the coils and transformers wore out pretty quickly. We also managed to fire frozen grapes dipped in a batter of glue and iron filings. They weren't as hard on the drywall.

[Chucky]

The Punkin Chunkin Community Responds!

Hi Bob,

As a long-time competitor at the WCPC, I can answer a lot of your questions and have a good relationship with the president of the association.

Rail Guns have been discussed before and most think it would be very cool. I guess it would have to go into the Adult (formerly "Unlimited") Catapult category since you need 4 or 5 teams with similar characteristics to petition for your own class.

I agree that sheilding others from the EMP would be wise since no one wants there phones wiped clean or car ignition systems fried, but beyond that, I think you could get in.

A first time registrant need pics or at least drawings of their machine, with explanations of how it works, dangerous characteristics, if any, and $100 registrations fee. They aslo charge $30 a person even for you and you team mates for the weekend pass (the nerve).

Open registration for new machines begins June 1st and this year it was filled in less than 2 hours, as opposed to weeks or months in the past, so you have to be on the ball there.

I think you should do it. There's no rule against it that I can think of, as the real key ones don' tapply to you: No explosives....well that's it.

Good luck and feel free to ask me any questions you might have.

Best would be to contact me directly, but I hesitate to post my personal contact info here. You could send me an e-mail via our team website, teamchucky.com if you like.

Best,

Dan

[Bob Thompson]

Hi Bob,

As a long-time competitor at the WCPC, I can answer a lot of your questions and have a good relationship with the president of the association.

Rail Guns have been discussed before and most think it would be very cool. I guess it would have to go into the Adult (formerly "Unlimited") Catapult category since you need 4 or 5 teams with similar characteristics to petition for your own class.

I agree that sheilding others from the EMP would be wise since no one wants there phones wiped clean or car ignition systems fried, but beyond that, I think you could get in.

A first time registrant need pics or at least drawings of their machine, with explanations of how it works, dangerous characteristics, if any, and $100 registrations fee. They aslo charge $30 a person even for you and you team mates for the weekend pass (the nerve).

Open registration for new machines begins June 1st and this year it was filled in less than 2 hours, as opposed to weeks or months in the past, so you have to be on the ball there.

I think you should do it. There's no rule against it that I can think of, as the real key ones don' tapply to you: No explosives....well that's it.

Good luck and feel free to ask me any questions you might have.

Best would be to contact me directly, but I hesitate to post my personal contact info here. You could send me an e-mail via our team website, teamchucky.com if you like.

Best,

Dan

Dan, Thank you for the info. It was quite helpful. I was about to post a new wrinkle in my quest to damage produce.
I spoke with a cohort with whom I have built some rather strange projects in the past. The rub will be the time it will take to fab the rare earth magnets is going to be extensive. After they are fabbed they have to be wound . The advantage of R.E. mags over wire over ferrous core mags is that they don't require as much shielding. Estimated time for R&D and then fab will take us a couple years.
However, I'm told there is a coalition from Caltec and JPL that are working on a railgun and may be ready for their debut next year in time for the tournament. I hope they can do it.
I will continue to explore my options vis-a-vis sending gourds down range.
My only other question is regarding refrigerating the pumpkins prior to launch, I couldn't find a specific prohibition when I read the rules.

[Bob2]

Bob,
If you freeze the pumpkins they will not flatten out and slow down upon launch time, trajactory will improve also.
Keep up the good work on the rail gun mine is going slow having trouble getting enough power to the particle ejector, Power company is mad when they have to come out and replace the transformer. when I have enough power 13.3Kva minimum acceleration is astronamical mach 8.77 at the ejector. with a noise level of 22db, wife says to quiet it down as I am disturbing the neighbors.

Goose hunting with it is excellent defeathers and cooks them all at once with no damage to the meat.

Keep it between the ditches.

Bob H.

[Chucky]

Hey Bob,

The rules state that you are not allowed to "alter" the pumpkins, however, it is often cold enough outside overnight at that time of year in Delaware to coat the ground with a hard frost, looks like snow fell. So, this is a bit of a gray area. One could easily claim that the gourds had simply been out all night and naturally froze.....I've never gotten a good answer to that exact question. Our theory is, however, that freezing them will remove any elasticity that they possess and they will tend to explode more easily due to their brittleness.

Keep in mind we don't use orange pumpkins, rather several varieties that possess desired characteristics for our machine: highest density possible, spherocity (is that a word?), or at least symmetry down the long axis if there is one. and general toughness. A quality pumpkin between 8 and 10 lbs will not fail when an adult bounces up and down on it.

Remember, the ability to move a pumpkin quickly is only part of the solution for great distance- the acceleration curve is also key. The air cannons have much more power than they need to throw a 10lb object over 1 mile, but the pumpkin is the big variable. Too many G's blow them up. They have been stuck just under 4,500 feet for maybe 5 years now. And still we gain. 1,100ft in 2009, 2,800 in 2010 and 3,636 this year. You do the math!

Also, if you can put backspin on the pumpkins, you are doing well. The cannons throw knuckleballs, to my knowledge, while machines like ours put a terrific backspin on the projectile, like a well-hit golf ball, allowing us to throw flatter and take advantage of the magnus effect.

Food for thought.

Dan

[Bob Thompson]

Hey Bob,

The rules state that you are not allowed to "alter" the pumpkins, however, it is often cold enough outside overnight at that time of year in Delaware to coat the ground with a hard frost, looks like snow fell. So, this is a bit of a gray area. One could easily claim that the gourds had simply been out all night and naturally froze.....I've never gotten a good answer to that exact question. Our theory is, however, that freezing them will remove any elasticity that they possess and they will tend to explode more easily due to their brittleness.

Keep in mind we don't use orange pumpkins, rather several varieties that possess desired characteristics for our machine: highest density possible, spherocity (is that a word?), or at least symmetry down the long axis if there is one. and general toughness. A quality pumpkin between 8 and 10 lbs will not fail when an adult bounces up and down on it.

Remember, the ability to move a pumpkin quickly is only part of the solution for great distance- the acceleration curve is also key. The air cannons have much more power than they need to throw a 10lb object over 1 mile, but the pumpkin is the big variable. Too many G's blow them up. They have been stuck just under 4,500 feet for maybe 5 years now. And still we gain. 1,100ft in 2009, 2,800 in 2010 and 3,636 this year. You do the math!

Also, if you can put backspin on the pumpkins, you are doing well. The cannons throw knuckleballs, to my knowledge, while machines like ours put a terrific backspin on the projectile, like a well-hit golf ball, allowing us to throw flatter and take advantage of the magnus effect.

Food for thought.

Dan

Dan, Have you considered a metered air discharge ? Perhaps an expansion chamber to mitigate the g forces imposed on the pumpkin at firing. I wonder if getting the pumpkin moving before the full force of the air charge brings it to max acceleration might allow for a higher capacity air chamber and consequently more loft and less pie. I have a couple other wierd notions that need vetting, but I'll Email those to you.
Re: the cooled pumpkins. I only wanted to chill them to approx 42f . They would remain elastic but they would also be more stable internally. We froze the grapes because it's quite difficult to coat room temp grapes with glue.

[Bob Thompson]

Oops, I just realized your machine isn't pneumatic.

[Gordon Maney]

I am trying to decide if this is total fiction or partial fiction.

[Chucky]

Clarification

Sorry, Bob, not to be clear enough.

Our first machiine, Chucky 2 (Chucky 1 was a prototype) was a straightforward roman torsion catapult (onager, mangonel, whatever) which uses a rope bundle to store energy and release it quickly. We competed first in 2001 and threw 380 feet or so. Over the next 7 years we tweaked and improved it until it seemed maxed out at 3,091 feet.
see here: http://www.youtube.com/watch?v=afjde...eature=related

We then built a new one from scratch, Chucky 3, using what we had learned and a new, compound design. We hope this one will beat all the air cannons (27 or so clones of one another that think they cannot be surpassed by a mechanical team with insane dedication- they are wrong) and possibly eevn throw 1 mile.
see here: http://www.youtube.com/watch?v=IEcY3...eature=related

So that's where we're coming from. Hope this explains what I neglected to lay out earlier in the thread.

For the record, not total or even partial fiction.

Dan