New Combustion Launcher
Posted: Fri Jul 18, 2008 12:23 pm
Gun Name: Hammer-time
Design: Basic Over/Under Advanced combustion with a few mods.
Chamber: 18” of 4” 280 PSI Sch. 40 (Double Sleeved) + 4” 90 & 4”-3” Street 90 = (5200 ML Interior)
Barrels: (1) 62” Long 2” Sch.40, (C:B 1.5:1) (2) 58” Long double sleeved 2” golf ball barrel 1.7” ID, (C:B 2.4:1)
(3) 96” 1.5” Sch. 40 (C:B 1.6:1)
Fuel: Off-Board Propane meter w/ regulator – On-Board portable pre-measured Fuel cells (7.5” of ¾” PVC) Custom triple diaphragm fuel cell loader with quick connects
Ignition: Piezo BBQ Igniter – Dual Stainless steel multi-point spark arresters wired in series and spaced evenly in chamber
Electrical: 24VDC Chamber Fan, Custom On-Board PVC Battery pack (3-9 VDC Batts.), Custom Off-Board Large Capacity Power Supply (4-6 VDC Batts.) Curly cord and plug for easy switching.
Accessories: 2” Adapted Threaded Barrels, 2” Ball Valve for Venting, Customized Safety trigger/handle, & Barrel support
Esthetics: Tri-Color Paint Job - Rust-Oleum Specialty Hammered Paint For Plastic - Paint Link (Black Combustion chamber, Silver Accessories, Dark Bronze Barrels)
Props: After much web research on ideas, innovations, and what-not’s (to do), Spudfiles had by far the most posts, pix, and relevant chat. Burnt Latke for C:B ratio & Fueling made easy. Can’t forget extra how to’s, technical data at Advancedspuds. Credit for my fuel system goes to homedepotpro. I knew I wanted propane but I didn’t want that clunky tank & meter on board, so I was going to have the metering device & tank as a kind of loader, until I saw HD Pro’s innovative setup.
C:B Ratio: I realize some of the barrel lengths are less than ideal as per the prevailing wisdom. I was trying to balance performance against portability, and also wanted to try and use what I had. I plan to pick up some 8 footers and do some experimentation. From what I can tell there is a big sweet spot between .5:1 – 1.5:1, but then the velocity and distance drops off drastically on either side of that range.
GB Barrel: My Golf Ball barrel has the biggest lack of volume problem, but sleeving those 2” Sch 40’s into one another was a bear, I won’t be doing that again, especially not a longer one. For those who haven’t done this – You have to cut a 7/8-1” slit out of the inside pipe then squeeze the gap shut and smash it into the outer pipe. Once you cut the inside pipe it loses its cylindrical integrity so becomes oval. This oval force along with the pipe trying to spread apart creates two different forces of friction which increases exponentially as more length of pipe is in contact with one another. If I do anything I will buck up for the SDR 21 (only available in 20’ lengths @ plumbing supply) and sleeve it into the sch 40 2”.
Mishap: In my anxious paranoia of getting a perfect seal on the combustion chamber I failed to leave myself a way back in, which was quickly remedied when the fan started making a weird noise and then ultimately quit working. The chamber is comprised of high pressure pipe with couplers over the top for a complete double wall structure. To replace the fan, I had to cut away the last coupler & glue without disturbing the last piece of pipe under it, so I could then glue the replacement coupler back over the pipe. Needless to say I added a threaded cleanout body at the end before the reducer & ball valve, which was much incentivized by the surgical precision required to re-enter the chamber. The fan it turns out was corrupted by my sloppy epoxy job (per the autopsy). The fan body was mostly cut away to allow it to fit perfectly in the round pipe, as a result, when I was gluing the fan in the chamber, I got some on one of the blades. This little bit of friction eventually took its toll on the motor.
History: This was technically my second gun, the first being nearly 15-years ago which was a standard in-line spray & pray, with a lantern lighter & a thirst for starting fluid. I believe it had an eating disorder as it would throw-up potatoes about 200 yards.
Haven’t really shot this one much yet, 10 or so shots in the shop with a ball of duct tape to tweak the fuel levels, one of the errant shots blew a hole through a piece of 1/4” plywood. I shot two golf balls; one of which went literally out of sight, the other much further than I can hit one.
Need to score a safe place to shoot and I’ll get some damage shots, and try and do some distance measurements. Also, as said, I want to check out barrel length performance next.
Design: Basic Over/Under Advanced combustion with a few mods.
Chamber: 18” of 4” 280 PSI Sch. 40 (Double Sleeved) + 4” 90 & 4”-3” Street 90 = (5200 ML Interior)
Barrels: (1) 62” Long 2” Sch.40, (C:B 1.5:1) (2) 58” Long double sleeved 2” golf ball barrel 1.7” ID, (C:B 2.4:1)
(3) 96” 1.5” Sch. 40 (C:B 1.6:1)
Fuel: Off-Board Propane meter w/ regulator – On-Board portable pre-measured Fuel cells (7.5” of ¾” PVC) Custom triple diaphragm fuel cell loader with quick connects
Ignition: Piezo BBQ Igniter – Dual Stainless steel multi-point spark arresters wired in series and spaced evenly in chamber
Electrical: 24VDC Chamber Fan, Custom On-Board PVC Battery pack (3-9 VDC Batts.), Custom Off-Board Large Capacity Power Supply (4-6 VDC Batts.) Curly cord and plug for easy switching.
Accessories: 2” Adapted Threaded Barrels, 2” Ball Valve for Venting, Customized Safety trigger/handle, & Barrel support
Esthetics: Tri-Color Paint Job - Rust-Oleum Specialty Hammered Paint For Plastic - Paint Link (Black Combustion chamber, Silver Accessories, Dark Bronze Barrels)
Props: After much web research on ideas, innovations, and what-not’s (to do), Spudfiles had by far the most posts, pix, and relevant chat. Burnt Latke for C:B ratio & Fueling made easy. Can’t forget extra how to’s, technical data at Advancedspuds. Credit for my fuel system goes to homedepotpro. I knew I wanted propane but I didn’t want that clunky tank & meter on board, so I was going to have the metering device & tank as a kind of loader, until I saw HD Pro’s innovative setup.
C:B Ratio: I realize some of the barrel lengths are less than ideal as per the prevailing wisdom. I was trying to balance performance against portability, and also wanted to try and use what I had. I plan to pick up some 8 footers and do some experimentation. From what I can tell there is a big sweet spot between .5:1 – 1.5:1, but then the velocity and distance drops off drastically on either side of that range.
GB Barrel: My Golf Ball barrel has the biggest lack of volume problem, but sleeving those 2” Sch 40’s into one another was a bear, I won’t be doing that again, especially not a longer one. For those who haven’t done this – You have to cut a 7/8-1” slit out of the inside pipe then squeeze the gap shut and smash it into the outer pipe. Once you cut the inside pipe it loses its cylindrical integrity so becomes oval. This oval force along with the pipe trying to spread apart creates two different forces of friction which increases exponentially as more length of pipe is in contact with one another. If I do anything I will buck up for the SDR 21 (only available in 20’ lengths @ plumbing supply) and sleeve it into the sch 40 2”.
Mishap: In my anxious paranoia of getting a perfect seal on the combustion chamber I failed to leave myself a way back in, which was quickly remedied when the fan started making a weird noise and then ultimately quit working. The chamber is comprised of high pressure pipe with couplers over the top for a complete double wall structure. To replace the fan, I had to cut away the last coupler & glue without disturbing the last piece of pipe under it, so I could then glue the replacement coupler back over the pipe. Needless to say I added a threaded cleanout body at the end before the reducer & ball valve, which was much incentivized by the surgical precision required to re-enter the chamber. The fan it turns out was corrupted by my sloppy epoxy job (per the autopsy). The fan body was mostly cut away to allow it to fit perfectly in the round pipe, as a result, when I was gluing the fan in the chamber, I got some on one of the blades. This little bit of friction eventually took its toll on the motor.
History: This was technically my second gun, the first being nearly 15-years ago which was a standard in-line spray & pray, with a lantern lighter & a thirst for starting fluid. I believe it had an eating disorder as it would throw-up potatoes about 200 yards.
Haven’t really shot this one much yet, 10 or so shots in the shop with a ball of duct tape to tweak the fuel levels, one of the errant shots blew a hole through a piece of 1/4” plywood. I shot two golf balls; one of which went literally out of sight, the other much further than I can hit one.
Need to score a safe place to shoot and I’ll get some damage shots, and try and do some distance measurements. Also, as said, I want to check out barrel length performance next.