i’d love to hear what you all think of this…
There is so much going on in the picture. I can take a guess but could you explain a little all the features?
yeah, sure. 
well, i guess to start, the most visible stuff would be the air horn (yes, it’s off a semi truck) which is on top of that BIG yellow air tank which is where the air is stored for the cannon barrel only. there are two on-board compressors that join to fill two small clippard cylinders, then go onto a T fitting where one end goes to a pressure sensor and a regulator for the pneumatic/air horn (i have yet to get another solenoid valve to overcome this problem) and the other end goes through a check valve attatched to the big air tank in front then leaves that tank to goto a electric sprinkler valve which feeds the cannon (the valve for the cannon is powered by a SPIKE relay going through a transformer that converts 12VDC to 120VAC then reduces down to 24VAC [that’s what the valve requires to function fully]). it also has a rotating light on the side (and yes it came off of a snow plow) that is turned on manually with a switch. it runs off of two gearboxes, each with two CIM motors that drive push-mower wheels (two, one on each side, in the back). the robot requires two 12VDC KOP batteries to run at a very good preformance. all of this is running off of one IFI Robotics kit, of course with extra IFI parts. it steers pretty good too, seeing it uses casters. oh i almost forgot, the pneumatic is (well, was being) run off of two single action FESTO valves, it still is, just with the air horn, it automatically raises (but as i said earlier, will be fixed). in the end of production, this will have tank tracks instead of wheels (also, they will be made of hinges). overall…this has a lot of fire power for 120 PSI. 
if you would like to ask anything else, please let me know.
How many shots on one tank of air?
I take it that the light and horns are used as a warning system, not just for the cool factor. If so, a wise move.
Also a wise move to not use a PVC tank; see the other threads this summer…
Are the batteries wired in series or in parallel (this can affect charging/performance)?
I see a lot of straps holding things down; are there plans to make those mounts a bit more permanent? If there’s any recoil, you may want that…
The wiring up top seems to be following the “spaghetti” plan of organization; that should probably be neatened up eventually (good practice for the electrical team…).
Overall, a pretty good design.
Is that a pneumatic cylinder for tilt?
i will answer the questions in the order they came…
this air cannon gets about 3, sometimes 4 shots, depending on if you want a very wimpy shot…lol
the light was mostly for cool factor, but it does help at night (seeing as i do live in the city…lol) when i am driving it around, just so cars will see it and not hit it. the air horn too was originally for cool factor too, but yes, it helps warn people that this will be firing in less than 10 seconds.
now to what everyone says NOT to do…the only piece of PVC that is being used is for the BARREL. the air storage tank just for the cannon barrel is that BIG yellow, metal tank. that was given to me before i had even bought the other parts to make this. so not once did i ever have PVC for the storage tank. hope i wasn’t being rough there, sorry if i was…
the batteries are in parallel, if you all remember right, the IFI control system only uses 12VDC.
there is no recoil whatsoever on the tank itself or the air horn, and also that is not the most recent configuration for the air horn (my camera broke recently, so that was the last picture, but i’ll have more on VERY, VERY soon) the air horn is on the front, far side of the robot in this picture.
actually, that red wire was the tether ( i say was because it fell down where the wheel is and got caught and nearly took off the tether port, dumb freaking move i know…but that is now off and on the OI.
Thanks for the compliments.
yes that is a 12" pneumatic cylinder to raise and lower the barrel with more positions than just low and high. you can move it to different positions because i used 2 FESTO single acting valves. if you want, i can go down and give you the schematic for the positioning system.
I understand that the tank is metal; we used to get a similarly sized black one in the KOP. Pneumatics weren’t exactly common while we had that… Something about no onboard compressor and the tank weighed about 12-13 lbs on a 130 lb robot (and the cylinder rules didn’t help).
I’m not sure that parallel batteries are the best thing, especially if you charge them in parallel. (There was a discussion on this earlier this summer, IIRC.) Being a mechanical, I defer to the electrical guys on that, though.
I wasn’t referring to the tether cable when I mentioned spaghetti. Matter of fact, I couldn’t tell there was a tether cable on there… this may be due to about 20-30 wires going all over the place.
oh, sorry. the wires are actually tied down, it’s just that there are so many of them in such a small area. anyway, thanks, and if you would like a schematic, i may be able to do something like that.
wow! That looks pretty cool! I’d love to see a video of this in action.
It looks to me like the “Spaghetti” of wires is just long PWM cables that were bundled together. add a few bundles… But otherwise it looks like all your wires are nicely tied down.
How far does it shoot an object? What object does it shoot?
I looked at it, and it doesn’t look like it would be charged in parallel. Each battery has its own connector to allow for a single battery charging. The first battery just runs to the second battery, which then runs to the power switch. Correct me if I’m wrong, but that’s just what I noticed. But you are correct in saying it’s not the best thing to charge them in parallel.
it can shoot T-shirts about 150’ when it’s at 120 PSI, but water bottles about 200’+. it’s especially fun to watch at night when there is a GlowStick in the water filled bottle. 
it can shoot anything that can fit in the barrel without too much force.
and i do usually charge them in parallel it just takes longer, a lot longer, but i still get the same battery power when they’re done charging. the reason i don’t charge them seperatly is because i only have one charger and a lot of school. and to answer your last question about a video or more it has been raining, A LOT, but i do plan on putting it on youtube sometime. i’ll tell you all the link and when i have posted each.
You may find this thread interesting reading: http://www.chiefdelphi.com/forums/showthread.php?t=77837
Admittedly, they were planning to run 6 batteries in parallel, but you should still pay attention, because quite a bit of what they said will apply to your case.
Yeah your right. Its just like having a larger battery. But Of course with that you should always watch out and make sure that its fully charged. I remember hearing that if one cell of the battery is not fully charged (since it charges in cells, and they talked about this in that thread) that the output of all the other cells will decrease. And if you were to have a dead cell, charging would definitely be a problem. But i suppose those are all issues to attack when they happen (mainly the dead cell thing)
But I would love to see a video of that thing. It looks awesome. I know from our cannons we shoot t shirts, but we put a soda can in front of it and it just flew! Quite a site to see.
Please keep us updated on any revisions and any new videos you take after it stops raining
That looks really good! could use a little organization, but overall its pretty awesome! as far as the batteries go, on our teams t-shirt launcher we are working on, we have one battery for the electronics and one battery for all of the motors and compressors. This way when the motor battery goes dead we can swap it out without turning off all of the lights/sounds and electronics. We are also planning to have enough battery boxes on the robot for close to 4-5 batteries, this will allow us to quickly swap the connection if the battery goes dead.
Hopefully this will help you in your further designing of this robot!!
-McGurky
Here is the link to the video you all wanted to see of the air cannon. ENJOY!