S.R.B.M. idea

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
Post Reply
User avatar
deathbyDWV
Corporal
Corporal
Posts: 576
Joined: Sat May 16, 2009 4:02 pm
Location: Owasso, OK

Thu Jun 04, 2009 2:00 pm

In this case S.R.B.M. doesn't stand for short range ballistic missile, but it stands for soda rocket bottle mortar. I was going to take an idea from this guy http://www.instructables.com/id/Gasolin ... her.-Desi/ but i wanted to use propane for the fuel and not have an air pump. Do you think it'll have good power at all or not really? I was thinking that his might just work much better because it is (kind of) a hybrid.
Life's too short to mark off the items on your wish list...
Top
User avatar
Technician1002
Captain
Captain
Posts: 5189
Joined: Sat Apr 04, 2009 11:10 am

Thu Jun 04, 2009 2:14 pm

deathbyDWV wrote:In this case S.R.B.M. doesn't stand for short range ballistic missile, but it stands for soda rocket bottle mortar. I was going to take an idea from this guy http://www.instructables.com/id/Gasolin ... her.-Desi/ but i wanted to use propane for the fuel and not have an air pump. Do you think it'll have good power at all or not really? I was thinking that his might just work much better because it is (kind of) a hybrid.
Propane provides a little less energy than gasoline. Using unpressurized instead of at 40 PSI shown in the video cuts the mass of fuel and oxidizer in the combustion chamber down to about 1/3. You can compensate some for the non pressurized chamber by making it a little larger and using a longer launch tube to accelerate over a longer distance using the lower pressure. In the dimensions given, the power will be considerably lower with propane and air if not under pressure.
Top
Post Reply

Return to “Combustion Cannons”