Cheap open source orbital capable rocket

[Armchair Rocket Scientist]

The idea is to make the rocket from materials you could by in your nearest hardware store, like this:

Fuel and oxidizer tank made from either sheet metal or fiberglass composite, fuel is diesel fuel or kerosene, oxidizer is liquid oxygen. Engine will be made from common metal, using pintle injector and piston pump, guidance using Arduino microprocessor and Sparkfun 6 DOF IMU, control using rollerons

Of course, with this low performance rocket, the only fitting payload is a Cubesat or some of it, but the point is everyone with some sort of machining tool could build it. And the design will be open source so everyone could build it. Hopefully, some workshop could be dedicated to build this rocket, reducing labor costs.

Now, is this possible?

All right...

First of all, kerolox is a bit ambitious. In amateur rocketry, there are a decent number of people building their own solid-fuel motors, a much smaller number with hybrids, and maybe two or three very well-funded teams (e.g. Copenhagen Suborbitals) building their own liquid-fueled engines.

Most likely, on a rocket like this it would be easiest to use solid fuel for all but the final stage, with the final stage using a pressure-fed engine (even SpaceX used a pressure-fed engine on the upper stage of the Falcon 1).

Now, based on the specs of the Scout and Lambda 4S, the final vehicle should have a mass of 10-20 tons, with 4 stages - 3 solid, 1 liquid or hybrid.

Potassium Nitrate and sugar propellant has HORRIBLE Isp. A much better fuel choice is ammonium perchlorate and aluminum powder. This is used in a lot of "real" SRBs, as well as in nearly all commercially manufactured hobby rocket motors with more than 20 N of thrust.

Let's assume the lower stages each provide 2500 m/s dV at Isp 230 s, with a fuel:structure ratio of 4:1, and the upper stage provides 3000 m/s at Isp 270 s, with a fuel:structure ratio of 4:1.

The fourth stage must be 68% fuel. Given a 4:1 mass ratio for the stage and a 10 kg payload, that gives a wet mass of 65.5 kg.

The third stage must be 66.7% fuel. Given a 4:1 mass ratio for the stage and a 65.5 kg "payload," that gives a wet mass of 393 kg.

The second stage must be 66.7% fuel. Given a 4:1 mass ratio for the stage and a 393 kg "payload," that gives a wet mass of 2360 kg.

The first stage must be 66.7% fuel. Given a 4:1 mass ratio for the stage and a 2360 kg "payload," that gives a wet mass of 14200 kg.

For the fourth stage, with a TWR of 0.5 we need 300 N of thrust, with a burn time of about 400 seconds. With a liquid stage, we can do that. With a hybrid, we are likely to get a burn time of at most 30 s, giving a thrust of 4 kN and a TWR from 6.2 to 19.5

For the third stage, we are likely to get a burn time of at most 40 s, giving a thrust of 15 kN and a TWR from 3.9 to 11.7

For the second stage, we are likely to get a burn time of at most 40 s, giving a thrust of 90 kN and a TWR from 3.9 to 11.7

For the first stage, we are likely to get a burn time of at most 60 s, giving a thrust of 360 kN and a TWR from 2.6 to 7.8.

Now, to get a sense of the scale of this project, the most powerful amateur rocket I know of used a motor with 55 kN of thrust and a 10 s burn. The first stage of this rocket would 6.5x the thrust and 39x the impulse.

Building something like this might be possible, but it would most likely require millions of dollars, and designers with day jobs as aerospace engineers.

[Aghanim]

And... there's where you get it wrong. 1 cubesat weighs at 1 kg

Assuming fuel tank and rocket engine at 20 kg, structural bracings at 1 kg for lower stages, payload at 1 kg

We want orbit injector to be at 3000 dV, so plugging that into the rocket equation:

Dry mass= 1+20 = 21 kg

dV = 3000 m/s

Isp = 270 s

Wet mass = 65 kg

Intermediate stage:

Dry mass = 65 + 20 + 1 = 86 kg

dV = 2500 m/s

Isp = 230 s

Wet mass = 245 kg

Launcher stage 2 :

Dry mass = 245 + 20 + 2 = 267 kg

dV = 2500 m/s

Isp = 230 s

Wet mass = 809 kg

Launcher stage 1 :

Dry mass = 809 + 20 + 3 = 832 kg

dV = 2500 m/s

Isp = 230 s

Wet mass = 2522 kg! I'm starting to think that this project isn't feasible...

Edited May 23, 2014 by Aghanim
I forgot 1 stage

[Comrade Jenkens]

That's gonna be one big rocket...

by amateur standards anyway.

[Elthy]

This whole idea of an amateur rocket to orbit set my brain on fire, now i cant stop thinking about it...

Edit: With an much smaller satellite (about 10g) the rocket will be much smaller, too. The problem is that you cant build an attitude controll system for a last stage thats only about 3 kg. So i thought that the best choice for a last stage would be a solid state (i doubt someone ca build a liquid engine that small) rocket which is spin stabilized by its predecessor, which also carries the controll system.

Edited May 23, 2014 by Elthy

[Aghanim]

Now, let's again assume we already build the orbital rocket. How do the rocket know its current height, apoapsis and periapsis?

[Elthy]

It doesnt need to know it. The rocket just needs to execute preprogramed maneuvers, since the exact orbit is not important it wont matter if its a few kilometers of.

[sgt_flyer]

Actually, the rocket being able to do corrections might be useful - especially when crossing such things as the jet stream - the air speed - especially on a lightweight rocket - could easily throw it off course.

[andrew123]

If you want to reach anywhere near the Karman Line, let alone LEO, the only option would be hydrogen peroxide.

It's very powerful, if you leave out the inconvenient fact that it has blown off many fingers after being exposed to catalysts such as micro dirt and dust.

Edited May 23, 2014 by andrew123

[lajoswinkler]

Orbital capable rocket? That's an intercontinental ballistic missile. If just anyone could make it, this world would look a lot more different.

No, an ammateur can't make this at home. The best thing he can make (given the option of plentiful financial resources) is a suborbital rocket for reaching above 80 or 100 km. That's it.

I wouldn't want to live in a world where anyone can throw stuff at you from any place on Earth.

[luizopiloto]

the problem with this idea... temp variation... normal metals will expand and retract too much with the temperature variations up there... causing structural failures... insulation leaks... fuselage deformations... at start will be heat from the supersonic speeds... the dinamic pressure from the supersonic shockweave... normal structures available on the hardwere shop can't handle this... then comes the freezing temperatures above stratosphere... this will make the expanded metal retract... causing all kind of structural failures...

real rockets use many kinds of special metals to endure this... something the hardware store don't have for sale...

[Aghanim]

There is such things as rules and regulations...

But nothing can stop the law of physics. An orbital capable rocket doesn't necessarily be able to carry a lot of payload. An ICBM that have a descent destructive capability needs a lot of payload capacity, which due to the tyranny of the almighty rocket equation, makes it hard to build

And it requires a reentry heat shield, which a layer of wood or charcoal could do the trick, or not.

Edited May 23, 2014 by Aghanim

[lajoswinkler]

Careful with that stuff. There's a reason not all amateur rocketeers have ten fingers.

And rcandy is not one of them.

There is such things as rules and regulations...

But nothing can stop the law of physics. An orbital capable rocket doesn't necessarily be able to carry a lot of payload. An ICBM that have a descent destructive capability needs a lot of payload capacity, which due to the tyranny of the almighty rocket equation, makes it hard to build

And it requires a reentry heat shield, which a layer of wood or charcoal could do the trick, or not.

You can put radiologically dangerous stuff as the payload. You can put viruses inside. You don't need to put anything, and it will still wreck havoc with the world. It might trigger a war.

[R0cketC0der]

Orbital capable rocket? That's an intercontinental ballistic missile. If just anyone could make it, this world would look a lot more different.

No, an ammateur can't make this at home. The best thing he can make (given the option of plentiful financial resources) is a suborbital rocket for reaching above 80 or 100 km. That's it.

I wouldn't want to live in a world where anyone can throw stuff at you from any place on Earth.

By this logic any plane is also a bomber.

[luizopiloto]

zirconium ceramic.... for the heat shield...

[StuntMax]

Well, ICBMs are not (necessarily) orbit capable... BUT they can deliver a several-100kg payload.

I think that a no-to-little payload orbital rocket MAY be possible, for an amateur with enough time and money to shed (and maybe a bit fexible about the idea of having all of his fingers attached to an hand).

[lajoswinkler]

By this logic any plane is also a bomber.

Doesn't matter. If a foreign country detects an ICBM going towards them, **** will hit the fan. Don't you realize how big of a political impact these things have?

Even if the missile is intercepted, many people will get hurt by others.

Well, ICBMs are not (necessarily) orbit capable... BUT they can deliver a several-100kg payload.

I think that a no-to-little payload orbital rocket MAY be possible, for an amateur with enough time and money to shed (and maybe a bit fexible about the idea of having all of his fingers attached to an hand).

If your rocket can establish orbit, you can bomb another continent. The moment another country's intelligence realizes this, tension starts.

We don't need that. Just look at the crazies out there. Putin, Kim Jong Un and lots of other military nutcase criminals high in the hierarchy.

[Aghanim]

Putin already have orbital rocket tech, Kim Jong x already orbited their ~1 metric ton satellite

And given enough money, amateurs could build orbital rocket. The deltaV calculations that is kinda optimistic suggests that 1 kg payload could be lifted by 2.5 metric ton launcher. The physics is there, it just waits to be tapped. They just need 3 230 s rockets and one 270 s rocket, something that hybrid could possibly provide

And this is already been discussed before:

Only problem with a reliable open source rocket is anyone with the proper tools could build it. North Korea, for example.

You know it's amusing how arrogant some people are, whose to say they don't already know how to build one?

the problem with this idea... temp variation... normal metals will expand and retract too much with the temperature variations up there... causing structural failures... insulation leaks... fuselage deformations... at start will be heat from the supersonic speeds... the dinamic pressure from the supersonic shockweave... normal structures available on the hardwere shop can't handle this... then comes the freezing temperatures above stratosphere... this will make the expanded metal retract... causing all kind of structural failures...

real rockets use many kinds of special metals to endure this... something the hardware store don't have for sale...

Now this is interesting. Structural load will be high, especially at the bottom stage, but with properly designed joint expansion and contraction will be no issue. But this also highlights why my OP 1 kg payload rocket might be too impractical for a amateur, so let's scale down, to N-prize. N-prize rocket only needs to lift several 10 grams of payload, and Wikisat is one of them. Well, assuming kerolox propellant for the OP rocket, the actual tank could be created from fiberglass and using hardware store rebar rods to strengthen the entire rocket. My deltaV calculation provides 23 kg for the dry mass budget for each stage, and that is probably too little

[christok]

And rcandy is not one of them.

It precisely is one of them. When I grabbed an example out of the air, I was thinking of actual injuries rather than imagined ones. And I happen to detest government bans on homemade rockets/rocket fuels.

Please don't be offended when I remind people to be careful with a dangerous procedure. You are free to be reckless with your own safety if you wish. (Provided you do so far away from me.)

By this logic any plane is also a bomber.

Very nice counter-argument. I'll have to steal it.

[Aethon]

Couldn't we launch a much smaller rocket (essentially an upper stage) by balloon to Baumgartner height. With an equatorial launch and a stiff prograde breeze, some reaction wheels to point it- heck, you could rig a tiny camera to broadcast real time on board instrumentation...get a couple of KSP ham radio operators around the globe to help track...get some of the players who build their own mission control rooms... Hmmm.

[Elthy]

I thought about an ballon-assited rocket, too. But im not sure to orientate the rocket when the ballon is up there and not hold by anything...

[christok]

I thought about an ballon-assited rocket, too. But im not sure to orientate the rocket when the ballon is up there and not hold by anything...

Gravity. In exactly the same way as you would orientate something hanging from a string attached to the ceiling.

Edit: Okay, that was stupid. You meant to get into a particular orbit. Integrate a compass/magnetos into the electronics. Either rotate it electrically or wait for the rocket to randomly rotate in the right direction.

Edited May 23, 2014 by christok
Expanding.

[Aethon]

... and gyroscopes/reaction wheels.

[K^2]

Doesn't matter. If a foreign country detects an ICBM going towards them, **** will hit the fan. Don't you realize how big of a political impact these things have?

A rocket with 1kg payload is not even going to make a blip on any early warning system. You're more likely to get in trouble with your local aviation authority than any government.

In a long run, if these things do become affordable enough for some shady people to start making them, yeah, I'm sure they'll get more sensitive equipment and require formal approval for launch. But since that's not going to happen without some major revolution in propulsion technology, it's an academic point.

Couldn't we launch a much smaller rocket (essentially an upper stage) by balloon to Baumgartner height.

So you just went from a ~9km/s requirement down to ~8km/s. That's not something an upper stage can manage. You still need most of your rocket, as well as one hell of a balloon.

Edited May 23, 2014 by K^2

[cantab]

By this logic any plane is also a bomber.

Or a guided missile, as the world learnt in 2001.

But anyway, there's going to be a minimum size of object that can make a safe re-entry. The kind of amateur orbital rockets being talked about are sending stuff up that's probably too small. Though the fact that the same rocket could loft a larger payload in a suborbital trajectory may be a concern.

Also, a rocket launch is going to be noticeable and is already regulated. Follow the regulations, get approval, and you and the world will be fine. Launch without approval and you won't be launching more than once. (You *might* launch without being noticed from the middle of the ocean, but that just looks suspicious and you'll probably have an unpleasant time when your launch does get found out about.)

[andrew123]

If you really want to be insane, put signature amplifiers like foil and cesium into the payload along with a trajectory to China from Montana. Don't forget the heatshields, we need to make it look like a minuteman 3 with MIRVS, which were supposedly decommissioned by START.

You should aim for Beijing. It would create more fanfare.

Edited May 23, 2014 by andrew123