Challenge: build an improvised rocket.

[sevenperforce]

Alright, here's an idea for you. Using only items you have in your home right now, try to build a rocket capable of lifting off vertically under its own power. If you happen to have actual rocket parts laying around, you cannot use them. Improvisation only.

Now, if you aren't at home, or don't feel like building it, you could also suggest plans for how to go about building it, using what you know you have at home.

I tried the other day, using a pen, the pen cap for a diverging nozzle, and hairspray. Either the rocket was to fuel rich or the choke point was too large, because it burned merrily until the whole thing melted, but never budged. 

[StrandedonEarth]

I once used butane in an empty rifle shell casing, and sent it bouncing around a friend's basement....

There must be a way to make a water rocket with a 2-liter pop bottle and an air pump/compressor

[sevenperforce]

Oh, the taper on the casing must have worked well. I made nice little legs for my Bic rocket but it didn't ever develop thrust....

I would add "must be a chemical rocket" just to make things exciting. 

[Temstar]

I have at home:

• bike tire pump
• CO2 cylinders, as I have a sodastream machine
• lots of soft drink bottles, including those particularly strong sodatream bottles that can easily handle 100+ psi
• pneumatic parts like push to fit fittings, pneumatic hose, three way valve, ball valve, one way valve etc
• endless tap water
• a lot of tools, like the ever useful hand hold rotary tools (knock off Dremel)

You can see where I'm going with this:

Spoiler

 

Edited February 24, 2016 by Temstar

[Exploro]

I know they are here in the house (boxed somewhere).

A simple balloon inflated with the air from my lungs; your household rocket in the simplest form.

[StrandedonEarth]

1 hour ago, Temstar said:

I have at home:

• bike tire pump
• CO2 cylinders, as I have a sodastream machine
• lots of soft drink bottles, including those particularly strong sodatream bottles that can easily handle 100+ psi
• pneumatic parts like push to fit fittings, pneumatic hose, three way valve, ball valve, one way valve etc
• endless tap water
• a lot of tools, like the ever useful hand hold rotary tools (knock off Dremel)

You can see where I'm going with this:

  Hide contents

 

Oh the Kerbanity! @SQUAD should give you an honorary kerbonaut suit for that!

How tall was that thing? Liftoff mass?

Edited February 24, 2016 by StrandedonEarth

[Temstar]

30 minutes ago, StrandedonEarth said:

Oh the Kerbanity! @SQUAD should give you an honorary kerbonaut suit for that!

How tall was that thing? Liftoff mass?

Nah it's not mine, it's just a illustration of what I would make.

People get really into water rockets, it's quite possible to do things like cutting open the top and bottom of a bottle so that it's a cylinder, and then stitch multiple together to create a taller tank just as we do in KSP. It's even possible to set up both parallel and serial staging to create a multi-stage water rocket.

[magnemoe]

4 hours ago, Temstar said:

Nah it's not mine, it's just a illustration of what I would make.

People get really into water rockets, it's quite possible to do things like cutting open the top and bottom of a bottle so that it's a cylinder, and then stitch multiple together to create a taller tank just as we do in KSP. It's even possible to set up both parallel and serial staging to create a multi-stage water rocket.

https://youtu.be/8JKa7ic0ONs
Is pretty insane, think they uses very high pressure too. 

[problemecium]

I have about 25 empty 2-liter Coca-cola bottles lying around my place at the moment. It'd be so easy I don't even feel like actually doing it xP

[kerbiloid]

 

[RizzoTheRat]

Tap water, car battery... now to try and harness that squeaky pop...

[GoSlash27]

Kerbiloid beat me to it.

 

[StrandedonEarth]

1 hour ago, kerbiloid said:

 

I forgot all about these!  I use to make something similar when I was a kid: 2 wooden matches laid head to head, then wrap the heads together with foil (cigarette-pack foil worked best because of that bit of paper lining). Stick one end in a crack in a log, hold a flame under the foil..

Edited February 24, 2016 by StrandedonEarth

[SinBad]

Im not sure this is a socially responsible challenge...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Elthy]

Baking Soda and vingear are also possible propellants...

[p1t1o]

I saw a news story once about a housefire and a can of deoderant. Basically, said can was on top of a Hi-Fi, the Hi-Fi started a small electrical fire, into which the can of deoderant fell, where it was heated until a small BLEVE (see link below) occurred. The following explosion seperated the roof from the house. It didn't blow it completely off, it just sorta lifted it and it fell back to roughly where it was, but the whole roof came away.

 

Anyhoo, thats a lot of energy from a very small container, I wonder if there are any household objects that could contain/control it enough to form a propulsive jet.

 

https://en.wikipedia.org/wiki/Boiling_liquid_expanding_vapor_explosion

[Spaceception]

8 minutes ago, Elthy said:

Baking Soda and vingear are also possible propellants...

I don't think that's as strong, it'd need to be pressurized, are there other (More powerful) chemical reactions?

[Elthy]

Afaik none that are legal in germany...

[Temstar]

1 hour ago, p1t1o said:

I wonder if there are any household objects that could contain/control it enough to form a propulsive jet.

Here's one fairly common source of energy:

16g CO2 cartridges, generally used by bike riders as an emergency source of air to pump up their tyres without carrying a pump. By my calculation a 16g cartridge which is a little bit bigger than an AA battery can release 7L of CO2 at standard pressure and temperature, and it can do this nearly instantaneously. You can buy them easily from bike shops.

 

And of course good old dry ice. Mix it in a bottle half filled with water and wait. The water will quickly warm up the dry ice so it becomes CO2 gas and build up the pressure. When the bottle finally lets go all that CO2 under huge pressure will fire the water out at pretty impressive velocities.

[sevenperforce]

What kind of ISP could a dry ice cannon develop, theoretically? Would it be able to use a converging/diverging nozzle and achieve supersonic exhaust velocities?

A high-thrust design would be set up so that the hot water was also the propellant.

I was originally thinking specifically of chemical rockets based on combustion rather than something like phase change, but this is quite interesting. 

[p1t1o]

52 minutes ago, sevenperforce said:

What kind of ISP could a dry ice cannon develop, theoretically? Would it be able to use a converging/diverging nozzle and achieve supersonic exhaust velocities?

A high-thrust design would be set up so that the hot water was also the propellant.

I was originally thinking specifically of chemical rockets based on combustion rather than something like phase change, but this is quite interesting. 

Cold CO2 is safe(ish) to work with but doesn’t make the best propellant, it tends to solidify in the exhaust, removing a lot of energy from the system.

Adding water to the system, doesn’t add any energy, but adds reaction mass, reducing exhaust velocity.

That makes a cold CO2+water “rocket” a high thrust/low Isp option.

Other than the fact that the CO2 is cold (and sublimates) it is no different conceptually, from combustion product gases that drive a conventional rocket.

The water however, will not be accelerated very efficiently in a normal convergent/divergent nozzle as the water will not expand out of the nozzle. It will accelerate as the nozzle converges, but will decelerate again as it diverges. Pumpjets (as in jetboats or jetskis) are essentially "water rockets", and they use a "venturi"-type convergent-only nozzle.

CO2 following it will expand, of course, and may achieve supersonic speeds, but with all that water mucking things up I doubt the efficiency will be great.

Of course, you could leave out the water and heat your CO2 up nice and hot (mostly eliminating solidification losses) but now you pretty much have a normal rocket!

[magnemoe]

4 hours ago, p1t1o said:

I saw a news story once about a housefire and a can of deoderant. Basically, said can was on top of a Hi-Fi, the Hi-Fi started a small electrical fire, into which the can of deoderant fell, where it was heated until a small BLEVE (see link below) occurred. The following explosion seperated the roof from the house. It didn't blow it completely off, it just sorta lifted it and it fell back to roughly where it was, but the whole roof came away.

Anyhoo, thats a lot of energy from a very small container, I wonder if there are any household objects that could contain/control it enough to form a propulsive jet.

https://en.wikipedia.org/wiki/Boiling_liquid_expanding_vapor_explosion

Yes, if you heat liquid so it boils in an closed container generating pressure it cause the container to burst giving an explosion.
Now if the liquid is flammable you can easy get an fuel air explosion, this is insanely powerful and dangerous. Up to 10 times more powerful than TNT. Fuel air explosives are used by the military for air burst bombs.
Note that this does not work as an rocket engine you need to mix the fuel and air for the secondary explosion. 
 

[PB666]

Yes, indeed lets not encourage people to build rockets unless they can get some expert help, seen a couple of deaths associated with home-made explosive and one fellow missing the end of his foot.

 

[p1t1o]

55 minutes ago, magnemoe said:

Yes, if you heat liquid so it boils in an closed container generating pressure it cause the container to burst giving an explosion.
Now if the liquid is flammable you can easy get an fuel air explosion, this is insanely powerful and dangerous. Up to 10 times more powerful than TNT. Fuel air explosives are used by the military for air burst bombs.
Note that this does not work as an rocket engine you need to mix the fuel and air for the secondary explosion. 
 

What in my comment made you think I didn't know what a bleve was lol!

 

Wouldn't make for a conventional rocket, but could give a pretty good initial impulse I bet. Like an RPG, which uses all its propellant before leaving the tube.

 

16 minutes ago, PB666 said:

Yes, indeed lets not encourage people to build rockets unless they can get some expert help, seen a couple of deaths associated with home-made explosive and one fellow missing the end of his foot.

 

Nothing here that can't be found on Google in less than a minute.

And it's too late for KSPers, we are already interested in explosions!

All kidding aside though, you are entirely correct.

Even professional explosives personnel often have parts missing.

Edited February 24, 2016 by p1t1o

[magnemoe]

46 minutes ago, p1t1o said:

What in my comment made you think I didn't know what a bleve was lol!

Wouldn't make for a conventional rocket, but could give a pretty good initial impulse I bet. Like an RPG, which uses all its propellant before leaving the tube.

The rocket effect is just by the expanded gasses, you would get an larger effect with steam. The fireball happen afterward as the gass mixes with air. 
Normal gas leaks are les dangerous as the gas is not so well mixed with air.