Orbit-Capable Homemade Rocket

[p1t1o]

27 minutes ago, RainDreamer said:

What I mean by my statement is that, if we get to the point where amateurs can reach orbit, then actual space programs has already gone so, so far beyond. 

And well now that I think about it, that may also mean anyone with bad intention may shoot down sattellites or hold them hostage. 

Its like a baby-version of the Kzinti Lesson: "A reaction drive is a weapon, powerful in direct ratio to its efficiency."

It makes one think about whether or not amateurs should be allowed to reach orbit, akin to letting people drive on the motorway without a license.

[Camacha]

1 hour ago, p1t1o said:

It makes one think about whether or not amateurs should be allowed to reach orbit, akin to letting people drive on the motorway without a license.

As with anything, the good people will adhere to the law and rules and the bad ones will not. Banning it will certainly limit the amount of incidents, but it will not stop a determined evildoer.

[p1t1o]

1 minute ago, Camacha said:

As with anything, the good people will adhere to the law and rules and the bad ones will not. Banning it will certainly limit the amount of incidents, but it will not stop a determined evildoer.

All good points. Though my personal opinion is you cant separate the "good" people from the "evildoers", in any given population you will find a roughly similar proportion of both. I believe in gun control - whether absolute or not is another debate ("control" doesn't have to mean a total ban), but if one believes in gun control, one must also believe in rocket control. Much in the same way that I believe people should take lessons and get a license before being allowed on the roads.

But lets not derail this thread with a boring debate on rocketry ethics, considering the scale of the topic, its hardly a burning issue.

[wumpus]

Cost?  You ought to see the size of "big boy" model rockets.  If a hobby attracts a certain type (often middle-aged men.  Competitive middle aged men) they will spend enormous sums of money if only to show they can.  Getting to orbit might be like fielding a yacht, but don't expect cost to stop everyone (although the "amatures" might be like John Carmack instead of Musk and Bezos).

Balloon launch?  The less atmosphere you fly through, the less you are fighting the scaling effects of aeronautics.  If your ISPs are equal (they're not), you should get the same mass ratio as the "real" rocket programs (thus launching nanosats instead of things measured in tons).  Don't forget you can optimize the nozzle for [near] vacuum, that should help a lot (unless you need a lot of stages, which I suspect you would).

Additional legal issues.  While the idea that someone could launch an anti-satellite device at will, you have to remember that from 1945-1989 several nations were concerned that someone could launch a missile from *anywhere* (such as from a submarine) and destroy multiple cities.  I'd expect that a means for instantly detecting such a rocket are already in place.

[peadar1987]

4 hours ago, p1t1o said:

Its like a baby-version of the Kzinti Lesson: "A reaction drive is a weapon, powerful in direct ratio to its efficiency."

It makes one think about whether or not amateurs should be allowed to reach orbit, akin to letting people drive on the motorway without a license.

I've looked at making solid rocket motors in the past, but oxidisers are hard to come by the in the UK. As someone pointed out, the only difference between a small solid rocket motor and a pipe bomb is the hole drilled in the end

[p1t1o]

1 minute ago, peadar1987 said:

I've looked at making solid rocket motors in the past, but oxidisers are hard to come by the in the UK. As someone pointed out, the only difference between a small solid rocket motor and a pipe bomb is the hole drilled in the end

Yup.

I'd have thought that you could get hold of at least benchwork (like 0-10 kilo range) quantities of potassium nitrate though? No?

1 hour ago, wumpus said:

 I'd expect that a means for instantly detecting such a rocket are already in place.

Of course, for decades. I dunno how they'd ("they" being the Russians, Chinese and USAians) respond to a launch out of the blue though, say if you launched from the middle of the sea without notifying anyone. I doubt you'd have a cruise missile converging on you, but I doubt they'd ignore it either.

[cantab]

1 hour ago, peadar1987 said:

I've looked at making solid rocket motors in the past, but oxidisers are hard to come by the in the UK. As someone pointed out, the only difference between a small solid rocket motor and a pipe bomb is the hole drilled in the end

My understanding is that solid fuel gets regulated as an explosive in the UK, which means it's heavily regulated, and complying with those regulations is beyond what the typical amateur can do. Once you want to go beyond what off-the-shelf motors can do, you might be better off looking at hybrid or liquid rocket engines if you're based in the UK - because those engines do not "intimately mix" fuel and oxidizer before combustion they are more lightly regulated.

You probably don't want to chance doing any of these things without legal advice and regulatory approval, not in this day and age when people have been jailed for 'terrorism' on a lot less.

Edited June 30, 2016 by cantab

[Kryten]

The smallest ground-launched vehicle currently in development is Japan's SS-520-4; able to put a single 3U cubesat into orbit for a GLOW of ~1900kg. Given that's professional solid fuel, even a 'zero-payload' orbital amateur rocket is unlikely to be any smaller. The largest amateur motors have been in the 350kg class, whereas SS-520-4's first stage is over 1500kg.

[wumpus]

3 hours ago, peadar1987 said:

I've looked at making solid rocket motors in the past, but oxidisers are hard to come by the in the UK. As someone pointed out, the only difference between a small solid rocket motor and a pipe bomb is the hole drilled in the end

My understanding is that "rocket candy" is the only solid fuel that can be made in moderate safety (that is, proper precautions and avoiding non-obvious dangers will allow you *a*chance* of being safe).  Pretty much anything else and you have a large chance of blowing yourself up.  This pretty much goes with any homemade explosives (I'm not sure if one or two of Alfred Nobel's sons blew themselves up, but that was a pretty good survival rate for that profession).

No idea if "off the shelf" model rockets exist in the UK (I know they were in danger in the US after 9/11, and I remember pointing out how dangerous they were when attached to a Ford Explorer [2000ish US news media joke]).  I'm pretty sure you can get ammonium perchlorate filled rocket engines, but I suspect you need some sort of license (tied to amature rocketry, more of proof of competence) for at least the bigger ones.  If even the gunpowder-filled ones are available, they are likely your best bet until you are ready to go with hybrid nitrous oxide/rubberish fuels (and I'd still assume plenty of model rocket stages if you want that last bit of delta-v).

[sevenperforce]

A perhaps-odd but suddenly burning question (no pun intended):

Would it be possible to have a staged-combustion dual-hybrid rocket?

Basically, you'd have two solid-fueled rockets, one which was exceedingly fuel-rich and one which was exceedingly lean. Neither would be particularly dangerous or explosive on their own. But their exhausts would feed a central reaction chamber where secondary combustion would take place essentially like a liquid-fueled rocket engine.

Might be good for amateur rocketeers to achieve greater engine sizes without as much risk of blowing themselves to bits. Each of the rich/lean solid rockets would be much more forgiving and have a much lower burn rate than a typical stoichiometric solid rocket.

Edited June 30, 2016 by sevenperforce

[Streetwind]

Doubtful that would work. Since the fuel is solid, it would come out of the respective pre-combustion chambers is big, irregularly shaped, brightly glowing chunks of terror. How are you expecting to mix them? Even in a true hybrid rocket, where only one of the propellants is solid and the other gaseous, you only get a combustion at the surface layer, which is slowly eaten away as gas continues passing by. There's no way you can get a complete combustion just by surface contact of two randomly shaped chunks that bump into each other for a fraction of a second and then exit out the back of the rocket...

[sevenperforce]

8 minutes ago, Streetwind said:

Doubtful that would work. Since the fuel is solid, it would come out of the respective pre-combustion chambers is big, irregularly shaped, brightly glowing chunks of terror. How are you expecting to mix them? Even in a true hybrid rocket, where only one of the propellants is solid and the other gaseous, you only get a combustion at the surface layer, which is slowly eaten away as gas continues passing by. There's no way you can get a complete combustion just by surface contact of two randomly shaped chunks that bump into each other for a fraction of a second and then exit out the back of the rocket...

Wait, that doesn't make any sense to me at all. Why would the fuel break apart and come out in chunks? It would be just like any solid or hybrid rocket: there's a burn layer which deflagrates into a gas, and that gas comes out the back end of the rocket. In this case, you'd have a very hot fuel-rich pressurized gas coming into one side of the chamber and a very hot fuel-lean pressurized gas coming into the other side of the chamber. They would react, combust, and shoot out the back end of the rocket.

[Streetwind]

Even in a fully homogenous, ideal mixture solid monopropellant, the grain continually sheds chunks as combustion happens. Thermal expansion from heat, vibration and the sheer release of energy makes the exposed surface crack and flake. You get quite a nasty spray of the stuff directly underneath the booster! But because the mixture is ideal for cmbustion, most of it actually does combust before it exists the nozzle, so it's not that big of a deal as far as combustion efficiency is concerned. If you go and intentionally don't combust most of the propellant, though...

I'll admit I have nothing to back this up, but my gut feeling from four semesters of chemistry says that this is not going to do you the favor of happening quite that smoothly

[magnemoe]

15 hours ago, peadar1987 said:

I've looked at making solid rocket motors in the past, but oxidisers are hard to come by the in the UK. As someone pointed out, the only difference between a small solid rocket motor and a pipe bomb is the hole drilled in the end

This works the other way too, as an teen we found some herbicide who could be mixed with sugar as an explosive like black powder. 
First we made an tiny bomb in an plastic box who worked well, then we tried making an pipe bomb. 
As we knew this was dangerous we knew an field they had made two 4 meter deep holes 8 meter apart for some irrigation. Bomb in one hole and we hide in the other.
Lighted the fuse and waited, no explosion but an load wheezing sound, the bomb had become an rocket, it jumped out of its hole and down into our there it was jumping around

Later we tried to make some rockets but none worked as well as the bomb. 

[peadar1987]

15 hours ago, cantab said:

My understanding is that solid fuel gets regulated as an explosive in the UK, which means it's heavily regulated, and complying with those regulations is beyond what the typical amateur can do. Once you want to go beyond what off-the-shelf motors can do, you might be better off looking at hybrid or liquid rocket engines if you're based in the UK - because those engines do not "intimately mix" fuel and oxidizer before combustion they are more lightly regulated.

You probably don't want to chance doing any of these things without legal advice and regulatory approval, not in this day and age when people have been jailed for 'terrorism' on a lot less.

Yeah, they don't like you doing it. If I could walk into a shop and buy some over the counter no questions asked, I might do it, but having to order over the internet and give out my details for delivery, I'm not so keen on. I'm a foreign national in the UK at a very sensitive time in terms of immigration and terrorism. I don't really want to take the risk so I can play with rockets!

13 hours ago, wumpus said:

My understanding is that "rocket candy" is the only solid fuel that can be made in moderate safety (that is, proper precautions and avoiding non-obvious dangers will allow you *a*chance* of being safe).  Pretty much anything else and you have a large chance of blowing yourself up.  This pretty much goes with any homemade explosives (I'm not sure if one or two of Alfred Nobel's sons blew themselves up, but that was a pretty good survival rate for that profession).

No idea if "off the shelf" model rockets exist in the UK (I know they were in danger in the US after 9/11, and I remember pointing out how dangerous they were when attached to a Ford Explorer [2000ish US news media joke]).  I'm pretty sure you can get ammonium perchlorate filled rocket engines, but I suspect you need some sort of license (tied to amature rocketry, more of proof of competence) for at least the bigger ones.  If even the gunpowder-filled ones are available, they are likely your best bet until you are ready to go with hybrid nitrous oxide/rubberish fuels (and I'd still assume plenty of model rocket stages if you want that last bit of delta-v).

Yeah, from what I've seen KNO₃ is by far the best oxidiser in terms of safety and stability. I've seen people talk about using flour, wax, or coal dust as propellants as well, but the results seem to be mixed.

I've seen designs where the fuel and oxidiser are just mixed in powder form and tamped down to form the grain. These obviously have poorer performance than designs where everything is melted and properly mixed, but they do avoid the danger of heating explosives inside. I get the impression an R-candy fire is pretty hard to put out, as it's generating its own heat and providing its own oxidiser. Very hard to break the auld fire triangle until the thing burns itself out.

16 hours ago, p1t1o said:

Yup.

I'd have thought that you could get hold of at least benchwork (like 0-10 kilo range) quantities of potassium nitrate though? No?.

Chemical supplies are only available to licensed teaching establishments. I don't think I could justify getting the university to buy me some for my PhD! You can get limited amounts as fertiliser over the internet, but I think it does tend to arouse suspicion. I'm pretty sure building your own pyrotechnics in the UK is illegal, so if I did end up getting a knock on the door from the police, the fact that I was only building a hobby rocket wouldn't cut much ice.

[Silver_Swift]

19 hours ago, p1t1o said:

But lets not derail this thread with a boring debate on rocketry ethics, considering the scale of the topic, its hardly a burning issue.

Well, you don't have to get into orbit to hit something in orbit, right?

But yes, this is likely off topic for this thread.

[cantab]

19 hours ago, Kryten said:

The smallest ground-launched vehicle currently in development is Japan's SS-520-4; able to put a single 3U cubesat into orbit for a GLOW of ~1900kg. Given that's professional solid fuel, even a 'zero-payload' orbital amateur rocket is unlikely to be any smaller. The largest amateur motors have been in the 350kg class, whereas SS-520-4's first stage is over 1500kg.

I'm surprised and impressed orbital launchers already go that compact. That starts to make the amateur orbital launcher look feasible, although one probably couldn't and shouldn't try it solely with off-the-shelf amateur motors.

18 hours ago, wumpus said:

No idea if "off the shelf" model rockets exist in the UK

They do, you can get Estes / similar black powder motors and also smaller composite propellant motors without needing special licenses.

[architeuthis]

Gotta love that 1950's style optimism: the neighborhood kids build a moon rocket in their back yard Rocketship Galileo style. 

In the spirit of the OT, the only serious explicitly 'garage team to orbit' type project is Paul Breed's Unreasonable Rocket. He has been working most of the required building block for his 50-gram picosat payload and OTRAG-style launch vehicle for most of the last 10 years. I've seen some of his stuff in person, like his 3D printed HTP/RP-1 bipropellant rocket engines, and his composite propellant tanks -- it's extremely impressive work.

A somewhat more realistic, yet still enormously ambitious project for amateurs is simply reaching the von Karman line itself. AFAIK only one team has managed this so far: the CSXT team with their 'Go Fast' extremely large single stage solid fueled rocket back in 2004. There are a number of teams vying to reach the von Karman line now, including Coppenhagen Suborbitals, Boston University's Rocket Propulsion Group, TU DELFT's DARE team, and the Portland State Aerospace Society. Some people (university students) are calling it the 'mini-space race'. I'm guessing one of these teams will manage the feat within the next 5 year or so. The question remains as to who will it be.

Edited July 3, 2016 by architeuthis

[Bill Phil]

If the payload is the rocket itself:

A nosecone that conceals guidance mechanisms, mainly computers, possibly something so old that it's 8 bit. C64, anyone? Maybe an Arduino or Raspberry Pi, if possible.

A stage that uses pressure fed engines feeding into a single large bell, which would hopefully have a large mass ratio.

Then I'd have a stage with the same engines, but with a larger diameter and a greater length, and each chamber would have one engine bell.

The first stage would use the same engines but with smaller bells, or maybe higher thrust engines.

Or, scratch all of that, and use an OTRAG inspired system.

[Astrofox]

If you're looking for an orbit capable rocket with a diameter of less than 1.5m...

https://en.wikipedia.org/wiki/Vanguard_(rocket)

 

Also, I wouldn't use an elastic rope due to the fact that it may not break in the fashion one would like, so I suggest some sort of launch rail system that's angled for an optimal gravity turn.

Plus, the drag induced by the bit of rope protruding would be rather significant, and maybe the rope wouldn't break at all (after all, rockets have a low TWR at launch, and therefore accelerate upwards fairly slowly, making such a rope rather redundant and may result in multiple failures...).

Also, extendable Nozzles on the first stage to help give a slightly higher Isp at a certain altitude, and therefore waste a little less Delta-V?

It's just a few ideas...

[Bill Phil]

What about reciprocating piston pumps? That's probably easier to build than a turbopump...?