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Maximum Distance for a combustion tater gun

Posted: Tue Aug 07, 2007 1:20 pm
by Rukus
I've only just got into this sport, but I was wondering what kind of distance can a big normal combustion gun throw a tater? What size gun?

Ive read back in the archives a guy had one that threw a tater 1/4 mile.
Is that possible?

Posted: Tue Aug 07, 2007 1:58 pm
by DYI
I believe the one you are talking about is BigBang's "Crusader", a very advanced metered MAPP gun that supposedly shot 530 yards with a golfball. At least one combustion has achieved confirmed supersonic muzzle velocities (dongfang built it), firing candle wax slugs, but I believe that it was over 15' long. It is possible to fire a tater 1/4 mile or farther, but guns that can achieve such things must be massive, with very long barrels to avoid the initial shock of the pressure wave from vaporising the spud. Taternator II certainly had the energy needed to fire at supersonic speeds with only a 4' barrel (and did with wax slugs), but the tremendous heat and pressure created from detonating 2x mixtures of oxygen and MAPP gas would literally turn the spud into a gas which would leave the barrel and condense on nearby objects.

Schmanman claims that his SWAT gun (a pneumatic) has fired a spud ~1 mile, but its overall length is almost 30'.

In short, it is possible, but not practical, for a combustion to fire a spud 1/4 mile.

Posted: Tue Aug 07, 2007 2:06 pm
by Pete Zaria
DYI is correct.

Potatoes are a very unaerodynamic projectile, which severely limits their potential distance. Additionally, if you put enough power behind a potato to lob it 1/4 mile, it'd probably blow the potato apart in the barrel.

My combustion gun has a roughly 250ci chamber (plus the volume of the U-bend....) and a 7 ft, 1.5" barrel. Metered propane, chamber fan, spark strip, etc... I can lob a spud around 250 yards on a good day. Golf balls go A LOT farther - I'd venture a guess of 450+ yards with the right angle, but I've never actually measured so don't quote me on that.

Peace,
Pete Zaria.

Posted: Tue Aug 07, 2007 2:37 pm
by jackssmirkingrevenge
If you're going for maximum distance, forget spuds or any other organic projectiles - you need a dart or arrow shaped projectile with a high sectional density (heavy but small diameter, to keep its momentum while cutting through the air) fired from a sabot in a long and wide barrelled cannon that ideally incorporates a favourable C:B ratio and a chamber fan.

Posted: Tue Aug 07, 2007 8:19 pm
by Rukus
Thanks for the comments. I guess if I want distance, I'll need to go with golfballs.

Posted: Wed Aug 08, 2007 2:56 am
by f.c
ive shot a marble possibly 700 meters with my combustion gun.

Posted: Wed Aug 08, 2007 3:49 am
by frankrede
A marble?
Hmm I highly doubt that.

Posted: Wed Aug 08, 2007 4:10 am
by jackssmirkingrevenge
f.c wrote:ive shot a marble possibly 700 meters with my combustion gun.
with this? Unlikely...

Posted: Wed Aug 08, 2007 2:25 pm
by frankrede
Unless he shot it down a mountain?lawl

Posted: Wed Aug 08, 2007 2:33 pm
by Pete Zaria
You know, any of us can say "Well I've shot a (name projectile) about (name insane, unlikely-to-achieve-distance) before."

The problem is, without actually locating the projectile and measuring the distance, all of these claims are just guesses, and usually optimistic guesses at that.

An accurate measure we CAN do, though, is the hang time of a standard projectile. Launch a marble, golf ball, etc.... nearly straight up (but not quite straight up for obvious reasons....) and time how long the projectile stays in the air with a stop watch.

Just my $.02

Peace,
Pete Zaria.

Posted: Wed Aug 08, 2007 2:48 pm
by jackssmirkingrevenge
Pete Zaria wrote:(but not quite straight up for obvious reasons....)
Given the wind factor, I think straight up is a pretty safe :) but I agree completely, until GPS transmitters are cheap and compact enough to be shot about, no one can really be sure of the sort of range they're getting.

Posted: Thu Aug 09, 2007 11:23 am
by joannaardway
You can use glow in the dark objects (lightsticks or other stuff painted with the goo from them works well) at night, in which case, finding the range is easy.

Posted: Thu Aug 09, 2007 1:59 pm
by jimmy101
joannaardway wrote:You can use glow in the dark objects (lightsticks or other stuff painted with the goo from them works well) at night, in which case, finding the range is easy.
Wouldn't that give you the range plus how far the round bounced and rolled after it hit the ground? Golfballs can move as far after they hit the ground as they did in the air.

Probably the best way to measure range would be to find a big lake. Put out spotters a couple hundred feet or so on each side of the shooter. The spotters can see the splash of the spud and use protractors mounted on tripods to measure the angle between the impact point and the bearing to the shooter. If the distance from spotter(s) to shooter is know then the range can be caluclated with a bit of trig. This is how model rocketeers measure the apogee of their rockets when the can't afford on onboard alitimeter.

Posted: Fri Aug 10, 2007 8:16 am
by Rukus
jimmy101 wrote:
joannaardway wrote:You can use glow in the dark objects (lightsticks or other stuff painted with the goo from them works well) at night, in which case, finding the range is easy.
Wouldn't that give you the range plus how far the round bounced and rolled after it hit the ground? Golfballs can move as far after they hit the ground as they did in the air.

Probably the best way to measure range would be to find a big lake. Put out spotters a couple hundred feet or so on each side of the shooter. The spotters can see the splash of the spud and use protractors mounted on tripods to measure the angle between the impact point and the bearing to the shooter. If the distance from spotter(s) to shooter is know then the range can be caluclated with a bit of trig. This is how model rocketeers measure the apogee of their rockets when the can't afford on onboard alitimeter.
I was thinking of using the protractor method myself after firing into the lake. It might not be 100% accurate, however it should provide a rough idea of the distance. Using the protractor method with the protractor at a higher elevation than the level of the lake should increase the accuracy. We have a large hill behind the cottage, so maybe I'll measure that elevation and try that.

I have a mapping GPS on my boat, so if I could be in the area and then drive over to the splash I should be able to provide fairly accurate distance info also. I'll give both methods a shot and see how they compare.

Posted: Fri Aug 10, 2007 8:36 am
by Hailfire753
Use google earth. Go to the tools menu, and click the measureing tool. works for me. Pretty accurate too.