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Killjoy's FEAR

Built a hybrid cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Killjoy's FEAR

Unread postAuthor: Killjoy » Wed Apr 25, 2007 1:46 am

FEAR
I built this cannon for a science fair project because I bet my biology teacher I could break the speed of sound with a potato (I already knew it had been proven, but he didn't). Anways, I named it FEAR mostly because everyone who has seen it says that they are now afraid of me, so i decided to give it an appropiate name.
It took close to three months of research, designing (in english class), and actual construction, and is the most powerful cannon i have ever built.

As a side note, trying to make good sealing welds with a MIG welder was rather hard, so my dad suggested i grind down the welds till they were smooth and then apply some sort of sealant to seal any gaps. I went one step further and apllied a vacum to the combustion chamber and then applied my sealent (which was seal-all, very nice stuff). Worked perfectly and haven't had a leak since.

Also,
I want to thank my dad, Nathan, for helping me seal my welds (did much of the grinding after I became to tired to safely do it myself), my best friend, Colton, who helped me set up, build, and buy many of the parts, and I would like to thank my mom, Anne, who restrained from banning me from ever building another cannon at my house again, and who also along with my dad funded part of this project.

Anyways, the cannon...

Combustion Chamber
6" diameter sch 40 steel pipe, 63" long. Recomended working pressure 650 psi at 400 F, burst pressure 1100 psi. Total volume approximatly 1809 cubic inchs (includes fittings and such).

Barrel
2"diameter sch 40 PVC pipe, 50 feet long. Seperated in 10' sections and connected together by modify couplings. Total volume approximatly 1884 cubic inches.

Ignition Source
Two car igniton coils connected in parrallel, which have a capacitor from a camera flash circuit discharged into them. The flash from the camera circuit is used as the switch to complete the connection between the capacitor and the igniton coils. This set up is able to produce approximatly 50,000 volts.
This is connected to a spark strip with 5 gaps, each one foot apart, evenly spread through the combustion chamber. These are mounted to a 1/4" steel rod which is mounted to a stainless steel 1" threaded plug and is screwed into 1" tee mounted on combustion chamber.

Burst Disk Set Up
A modified 2" steel coupling is bolted down with 4-1/2" steel bolts onto a piece of 2" sch 80 steel pipe welded to combustion chamber. Burst disks consist of 3 layers of duct tape with a piece of 1/4" plywood cut to fit over the duct tap. Other disks include layers of duct tape and pvc tape, duct tape and aluminum foil, and duct tape and pieces of tin cans (cut to fit).

Features
Air and fuel metering completly controled electonically by operator; Fuel, Vent and Arm switches all have safety covers to prevent accidental switching.
Large size allows more forgiveness when mistakes are made when adding air or fuel to cannon.
Able to achieve velocities up to 2700 fps with a potato (still currently being debated).
All parts on combustion chamber rated to a minimum of 1000 psi.

Total Cost and Time Spent
$20 dollars for combustion chamber
$350 for valves, gauges, all fittings, pipe and barrel
$100 for electonics and parts for control panel
$100 for other stuff.
Total:$570
Spent over 100 hours welding, manufacturing parts, and putting everything together.

The only current pic of FEAR assembled. (I apologize for lack of size and clarity, it was taken with a cell phone).
Image

The fuel/air metering system. Consists of 3 valves, two of which are
three-way valves (for the fuel meter and compressed air) and the one-way valve is for venting.
Image

The control panel (back and front). Propane regulator and air compresser gauge are mounted on the panel. The three top switches are (in order from left to right): vent, fuel, and compressed air. All valves work off of 24 volts.
The toggle switch on the bottom is for arming and charging the capacitor, and the pushbutton is for firing the cannon (discharging capacitor into igniton coils)
The control panel consists of a 3/16" thick steel plate, and has the labels for each switch stamped into the metal (sorry, the labels didn't get picked up by the camera).
Image

The main combustion chamber with everything mounted to it. Weighs close to 300 pounds.
Image

The burst disk holder.
Image

The back of the combustion chamber. The large gauge is a 1-100 psi guage with 1 psi incrments, and is for measuring the correct amount of compressed air; the small guage is for measure the combustion pressure and goes up to 1000 psi (a check valve is used to retain the pressure after the burst disk has burst).
The 1" tee is connected to a 1" sch 80 steel pipe nipple welded to the 3/4" steel plate. This allows the spark strip to be slid in to the combustion chamber (and be located in the center) as well as the fuel and air to be put in. This design allows only 2 holes total in the combustion chamber, one for the spark strip, fuel, and air; and one for the barrel.
Image

Damage to a 55 gallon drum using 2 golfballs as projectiles. The top of the drum is 3/16" thick steel.
Image

Videos
Potato being fired at sheet metal (wood stopped penetration).
Image

Two loosly wadded golfballs being fired at a steel drum (damage pic above).
Image
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Last edited by Killjoy on Wed Apr 25, 2007 1:53 am, edited 1 time in total.

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Unread postAuthor: chaos » Wed Apr 25, 2007 1:52 am

let me be the first to say very nice gun man, and you should be proud, you should be very proud of your work

man that thing is destructive.
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Last edited by chaos on Wed Apr 25, 2007 5:12 am, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 25, 2007 2:49 am

scary! and very impressive, but I still doubt that 2,700 FPS figure. What sort of penetration did you get with the drums? At that velocity, a 4 gram 0.223 bullet will punch straight through half an inch of steel plate. I'd expect a golfball weighing ten times more than the bullet travelling at the same speed would be capable of some exceptional penetration figures...

Edit: Sorry if this comment came across as being negative, FEAR is an excellent name for the feelings your creation inspires and I'm extremely jealous of the fact you have the space at your disposal to create and fire such a massive launcher.
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Unread postAuthor: rna_duelers » Wed Apr 25, 2007 4:02 am

Indeed a golfball at 2,700fps would have alot of energy but how well it would penetrate thick steel is debatable as there is a broader area of energy to be dispersed over,and a goldball doesn't have a heavy mass for its relative size.But still it would undoutably be able to turn cinderblocks and various other objects to cheese.


Ohh a nice cannon indeed,just wondering could you get some pictures of the chamber and such were there isn't so much other junk around.Some of the pictures its hard to tell what is apart of the cannon and what isn't.


Could some one do some simple math equations and find out the joules of energy of a golfball at 2,700FPS/45grams.Just interested to see how much energy this thing is capable of!

Again nice cannon.
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Unread postAuthor: Insomniac » Wed Apr 25, 2007 4:18 am

That is one helluva nice gun! Its the SWAT gun of hybrids :lol:

One question: How come in the vids the barrel goes fowards when it shoots, instead of the recoil pushing it back??? I'm confused.
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I wonder how much deeper the ocean would be without sponges.
Right now I'm having amnesia and deja vu at the same time. I think I've forgotten this before.

Add me on msn!!! insomniac-55@hotmail.com
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Unread postAuthor: Hotwired » Wed Apr 25, 2007 4:33 am

I had to watch both of those several times because I wasn't entirely sure I'd clicked on the other one.

Both look similar and end in "Oh s**t" :lol:

I'm wondering why the barrel is pulled forwards too...

If it is too long it creates a bit of a vacuum in the barrel and the force of the projectile would drag the barrel forwards before it left...

Or is there something else happening?
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 25, 2007 4:46 am

rna_duelers wrote:Could some one do some simple math equations and find out the joules of energy of a golfball at 2,700FPS/45grams.Just interested to see how much energy this thing is capable of!


Assuming the velocity figures are correct, for a 45 gram golfball travelling at 2700 feet per second, we get 15,285 joules or 11,239 ft/lbs.

That, ladies and gents, is the equivalent muzzle energy to one of these:

[youtube]http://www.youtube.com/watch?v=TWJp14tkBlU[/youtube]

:shock:

In spite of the scale of the launcher, I remain very skeptical of the velocity readings

unrelated footnote, isn't the host of "Future Weapons" one of the most annoying guys on TV :D
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Last edited by jackssmirkingrevenge on Wed Apr 25, 2007 4:48 am, edited 1 time in total.
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Unread postAuthor: integral » Wed Apr 25, 2007 4:48 am

Kinetic Energy (J) = [Mass (kg) x Velocity (mps)^2]/2

After some conversions and using that calculation... the theoretical muzzle energy of a golf ball @ 2700fps is 15238.42 Joules.

Nice freaking cannon btw. Just wondering if u did break the sound barrier with that beast and whether ur bio teacher paid up?

EDIT: damn jack beat me...
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Unread postAuthor: Hotwired » Wed Apr 25, 2007 4:51 am

Nigh on three times the speed of sound.

Oh yeah... there was a discussion earlier about this and that number. Have you chronied a blank fire and a solid round yet?

*edit: yes that guy is annoying, he somehow manages to make being the enemy seem more attractive than being on his side... In fact all "this is an uber weapon and we pwn those noobs with it" programs make me feel a bit like that...
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Last edited by Hotwired on Wed Apr 25, 2007 5:35 am, edited 1 time in total.
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Unread postAuthor: integral » Wed Apr 25, 2007 4:58 am

dumbass me... i was looking at the mv of 823m/s and didnt realise that...sigh :oops:
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Unread postAuthor: schmanman » Wed Apr 25, 2007 5:26 am

nice, really nice, but I too am very sceptical of the velocities.
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Unread postAuthor: ShowNoMercy » Wed Apr 25, 2007 5:53 am

Why is everyone skeptical of his readings? The gun is huge, very well constructed and looks the part. So maybe he is telling the truth and you guys are all jeealous.
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 25, 2007 5:58 am

ShowNoMercy wrote:The gun is huge, very well constructed and looks the part


No one is doubting that, it's an amazing achievement and I'll be the first to admit that I am jealous I don't have the space to build and fire such a monster - but as far as claiming close to mach 3 without solid propellant is concerned, the numbers just don't seem to add up in my opinion.
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Unread postAuthor: ShowNoMercy » Wed Apr 25, 2007 5:59 am

Maybe he is forgeting to tell us something? Maybe its a hybrid or something? This is why you stick to using compressed air as a propellant. Much easier to use and argue with.
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 25, 2007 6:13 am

The longest range black power rifles won't exceed 2,000 feet per second, I find it hard to believe that a mix of propane and air can do better. I could be wrong, of course, but i'll need concrete chronograph/damage evidence to prove it.
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