Smallest possible rocket

[T.Neo]

You appear to have misread here. The rocket's weight is listed as 10,050 kg, which is 10 050 kg in International notation or 1,005e4 kg in proper scientific notation, which is ten metric tons and fifty kilograms.

No, I meant 9kg payload. Unless I misread that as well.
I'd seriously doubt any rocket weighing 9kg would be able to make it to orbit.

 

[Orbinaut Pete]

No, I meant 9kg payload. Unless I misread that as well.
I'd seriously doubt any rocket weighing 9kg would be able to make it to orbit.

Well, in theory, it's possible.
A very small rocket would only need a very small amount thrust to get it out of the atmosphere. The only problem would be fuel. If someone invented some sort of "long-burning fuel" so you could say, put 1kg of fuel in the rocket and it would burn for an hour. Providing the engines were powerful enough to achieve orbit, it would be possible.
But it doubt it will ever happen.

Maybe a rocket that turns air into thrust

--EDIT--

Only problem is when you're out of the atmosphere!

--EDIT 2--
Or a rocket with a tiny nuclear reactor weighing no more than a couple of kg's

 

[T.Neo]

If someone invented some sort of "long-burning fuel" so you could say, put 1kg of fuel in the rocket and it would burn for an hour.

Isn't that essentialy just a high-Isp?

 

[Orbinaut Pete]

Basically, yes.

This may be useful:
http://www.dunnspace.com/isp.htm

 

[cjp]

Only problem is when you're out of the atmosphere!

Urwumpe described the air drag problem quite well I think. There are some disadvantages in being small.

Or a rocket with a tiny nuclear reactor weighing no more than a couple of kg's

Nuclear reactors need to have a certain minimum mass to become critical.

Could the smallest possible rocket have liquid fuel engines? If not, you are probably stuck to using solid fuels. I guess most normal liquid fuel engines that outperform solid fuels already have quite small components, so they can't easily be downscaled.

 

[T.Neo]

This may be useful:
http://www.dunnspace.com/isp.htm

Now THAT would be a useful program.

 

[RocketMan_Len]

The Air Force Performance Calculator *is* a good program to use... but it's rather difficult to understand. I prefer to use a program called ProPEP and its graphic-front-end, GUIPEP. http://lekstutis.com/Artie/PEP/

The biggest part of getting a rocket to orbit, though, is the mass-fraction. The more mass you use in structure and payload, the less you have in propellant. That's why designers use the lightest available materials for the structure. (Having dense propellants is also a plus... but that's a separate debate unto itself.)

 

[tori]

There is no real limitation to a rocket's size. The lowest (unreal) limit would be a rocket made of three particles. One particle separates at high velocity, thrusting the other two in a sub-orbital trajectory. The second particle separates at the apogee, inserting the third particle into orbit.

A real limitation is given by your propellant's Isp, which does get higher as chemistry goes forward.