I loves me some Punkin Chunkin. The current big boys are the air cannons, which are shooting eight to ten pound pumpkins almost 4400 feet.
What muzzle velocity would be required?
Mods: GQ or Game Room? The networks consider punkin chunkin a sport, but this is a pretty sciencey question.
Too late at night for me to check the math myself, but I found an online site that claimed muzzle velocities in excess of 500 mph.
Assuming level ground and optimum launching angle, and neglecting the effects of air resistance and the shape and rotation of the Earth, the range of a projectile is given by D = v[sup]2[/sup]/g , or v = sqrt(D*g). Google tells us that that’s a bit over 250 MPH.
Now, that range is much less than the size of the Earth, so we can get away with ignoring curvature of the Earth and the Coriolis effect, but air resistance is likely to be significant. That’ll mean that launch speeds have to be higher to overcome air resistance to travel a given distance, which makes engineer_comp_geek’s figure of 500 MPH plausible.
From linked article from a footnote in chacoguy’s article:
“They set up their cannon, which can fire pumpkins at speeds of up to 700 mph …”
““The warmer the weather, the higher the speed of sound,” he said, noting that the pumpkins tend to slow down as they approach the sound barrier. “When the air is warmer, the pumpkins can be launched faster without hitting Mach 1.””
:eek: Consider me awed. The thought of a pumpkin making a sonic boom…
They’re probably a long way from actually being able to break the sound barrier. Going just a little bit faster than Mach 1 is a lot harder than going just a little bit slower than Mach 1. And even if their cannon were up to it, their pumpkins certainly aren’t.
Clearly that means we must breed a sturdier pumpkin that can survive the pumpkin sound barrier!
They carefully choose their pumpkins already, and use tougher varieties. Genetic tinkering, ie. breeding pumpkins specifically for this contest, has come up before.
If we’re going to go this direction, maybe we could breed them with better aerodynamic properties. Most of those pumpkin trajectories are hardly ideal.
How about one that would grow into a tapered shape with slanted ridges like a rifled shotgun slug, that could fly like a football thrown with a proper spiral?
How about breeding them to have dimples like a golf ball?
Part of the contest is not making “pie” (the pumpkin must leave the barrel intact). Making an indestructible pumpkin takes away one of the major points of the contest, IMHO. Maybe that makes me a pumpkin purist.
If we’re going to talk purism, it doesn’t seem to me that the air cannons really belong in the contest at all, even though they get better distance than the other categories. If the idea is to apply modern engineering principles to devices operating on the general principals of ancient siege weapons, using compressed air is cheating just as much as using an explosive propellant. It should remain a contest between trebuchets, catapults and the like. Of course, the air cannons are the crowd pleasers.
I don’t know; I find there’s a certain æsthetic grace to a good trebuchet throw that any sort of gun necessarily lacks. I mean, you can actually see the treb working: It’s not all hidden away inside a barrel. And seeing a counterweight the size of a car falling conveys raw power a lot better than any bunch of pipes, tanks, and hoses can.
It seems like more aerodynamic pumpkins should be easy, though. Just grow them in a box, like they do for square watermelons.
Another vote against air cannons.
If we keep going the way we are, soon they’ll grow genetically engineered ferrous gourds in iron-rich soil & launch them using electromagnetic rail guns towards a target range in Spain. Sub-orbiting punkins sound fun, but *really *violate the spirit of modernized seige engines.
Air temperature (and therefore, density) is actually a big factor in a lot of things. Baseball players often talk about balls leaving/staying in the park because it’s a day/night game. Competitive shooters adjust their aim to fit the air characteristics. I think a lot of people get so used to high school physics “assume a spherical cow” problems that they underestimate how important the air is to competition success.
This I would love to see. How is that anything but a modern siege engine? Launching heavy, dense projectiles that aren’t self-propelled on a ballistic trajectory toward a target from outside the target’s own attack range? Sounds like a siege to me.
I just don’t think any organic pumpkin in the world ever could withstand rail-gun velocities. 
Just as a nitpick, iron would be a very poor choice for a railgun; copper would be much better. You may be mixing up railguns and coilguns.
Clearly we need to put together a Doper team, starting by growing pumpkins in containers to give the proper aerodynamic shape. Plus pie recipes.
My wife and I attended Punkin Chunkin this year. It was awesome. It was redneck heaven. People brought their own porta-potties! On TV the air cannons get all the attention. In real life they’re the most boring to watch. It’s like watching someone fire a gun. The punkin shoots so fast that all you hear is a WHOOOSH!!! then you see spotters way far away looking for the pumpkin. Now the Torsion category… that’s incredible to see in person. Imagine the sound a hickory stick makes when you whip it through the air. Now place that sound as if someone were whipping a telephone pole through the air. It’s indescribable and totally has to be seen in person to appreciate the awesomeness.
I wouldn’t go so far as to say that he’s over a thousand feet short. Yes, Big 10 Inch did shoot one that far; but that was in Moab Utah under the best conditions for a long distance shot.
Oslo said: “The current big boys are the air cannons, which **are shooting **eight to ten pound pumpkins almost 4400 feet.” Which is absolutely true. The regular distances being shot right now out of air cannons is in the 4400 foot range. He never said that was the max distance ever shot.
Just saw the special on TV this weekend, it was great. Anybody know how they control the release of the pumpkins on the centrifugal machines? It’s spinning way too fast to do it manually (I assume), but there doesn’t appear to be any noticable mechanism either. It looks like nothing more than a propeller on a motor, but somehow they seem to get a great trajectory most of the time. I would think the speed of the spin would also greatly impact when to optimally release it.
I think (and this is the way I would do it) that there is a physical switch that is turned on by pulling on the rope that sticks out and when the rotating arm comes around next time to that spot the switch hits the release of the pumpkin. The position of the switch would be of course influenced by the max speed of the rotating arm and probably is determined by trial and error in pre-competition testing.