[Spaceships] Black powder Rockets?
 

Lagâri Hasan Çelebi was said to have made a manned ascent in a gunpowder rocket WP

Assuming this legend was true, what would be the statistics for a Spaceships black powder rocket? I can find information on the specific impulse of small modern rockets (about 80s), but I'm not sure about what this would be with 17th-century materials, and I've no idea what the thrust-to-weight ratio is. I'm imagining it would be quite low, sub 1G.

Any ideas? Thanks.

Re: [Spaceships] Black powder Rockets?
 

If it were below 1 gee it wouldn't take off.

Lots of chemical rockets have pretty good thrust-to-mass ratios, and I think that solid-fuel and hybrid rockets' mechanical simplicity means really low weight-to-thrust.

Re: [Spaceships] Black powder Rockets?
 

Are you familiar with GURPS Spaceships?

Re: [Spaceships] Black powder Rockets?
 

By that, I mean, in GURPS Spaceships each rocket component gives some amount of acceleration. If a rocket gave 0.5 G, and the spaceship had three rockets, the spaceship would have 1.5 G acceleration.

When scouring for information, I've seen thrust-to-weight ratios of 3:1, 4:1 or 5:1 when discussing the minimum thrust for competitions of model rockets (the fuel for which I'm guessing is close-ish to black powder)

According to the GURPS Spaceships designer's notes, 5:1 would give 0.25 G (so you'd need 5 rocket components to achieve lift off).

I don't know if I'm interpreting this right, or if the figures scale up to a manned rocket.

Re: [Spaceships] Black powder Rockets?
 

A little. 10

Re: [Spaceships] Black powder Rockets?
 

Bear in mind that in GURPS Spaceships' terms the model rocket motors you buy consist of a engine and some fuel tanks, not just an engine. Listed thrust-to-weight ratios in the spec will be for the fully-fuelled motor at ignition, not for the almost-empty motor at flameout.

Re: [Spaceships] Black powder Rockets?
 

The commercial Estes model rocket engines are basically black powder. A modern formulation, of course.

Model/amateur rocketeers use all sorts of propellants, though, including liquid fuels. So just be sure your sources are specific.

Re: [Spaceships] Black powder Rockets?
 

My understanding of black powder motors is that they are prone to cracking. That probably causes issues when you try to make something the size of an SRB. On top of that, aluminum perchlorate is far easier to cast and has a higher energy density than powder.

Re: [Spaceships] Black powder Rockets?
 

Black Powder of that generation is usually assumed to be 60% to 80% as effective as later BP.

When the Mythbusters tried this in a segment called "Chinese Astronaut" or something like that their main result was scorch marks on Buster.

Nevertheless, the thing you seek could be built in Ve2. When I look there I see that TL3-4 solid fuel rockets are given a performance roughly 1/5th of that assigned to TL7 types. The only way to compensate for this would be to shorten the burn time. 6 to 12 seconds instead of 30 to 60 seconds.

Moving on to Spaceships I believe you would lower the Delta-V per tank by a similar percentage.

Re: [Spaceships] Black powder Rockets?
 

Yes I intend to give the rocket a good chance of catastrophic failure!

Re: [Spaceships] Black powder Rockets?
 

I see, thanks. I'm now looking at http://www2.estesrockets.com/pdf/Estes_Engine_Chart.pdf which shows initial weight and propellant weight. It looks like, roughly speaking in Spaceships terms, half the components would be chemical rocket, and half would be fuel tanks.

Re: [Spaceships] Black powder Rockets?
 

On the scale and at the TL you are talking, I'd suggest a Malf of about 6...maaaaybe 7. It'd probably be realistic to make it a Malf of 3....

Re: [Spaceships] Black powder Rockets?
 

Here's what I think I've worked out for the Estes E9-6.
From their chart, it has 25 N of thrust, an initial weight of 56.7 g and a propellant weight of 35.8 g. Wikipedia says its Isp is 85.51

Its acceleration is 25 / (0.0567 * 9.8) = 45 G

If the whole rocket was a GURPS spaceship, it would have 13 chemical rocket components and 7 fuel tank components. So the acceleration of one chemical rocket is 45 / 13 = 3.46 G

The delta-v per tank is 85.51 / 3000 = 0.03 mps

Does this seem cromulent?

Re: [Spaceships] Black powder Rockets?
 

It seems unlikely to be related to your basic question.

Re: [Spaceships] Black powder Rockets?
 

It gives me a ballpark figure? Thanks for helping.

Re: [Spaceships] Black powder Rockets?
 

So its dry mass (without propellant) is 56.7 - 35.8 = 20.9 g. It is 35.8/56.7 = 63% propellant and 37% engine.

I make that 7.4 engine components and 12.6 fuel tank.

I make that 45 gee / 7.4 = 6 gee per reaction engine.

I[sub]sp[/sub] of 85.51 seconds means that 20 tanks of fuel could (except for the changing mass ratio) produce 85.51 gee-seconds. And a gee is, umm, 32.17 ft/sec². So that's 2751 ft/sec. And a mile is 5280 feet, so it's about 0.52 miles/sec. Divided by twenty tanks is 0.026 mi/sec per tank. Close enough.

Re: [Spaceships] Black powder Rockets?
 

Mythbusters also took a shot at Lagâri Hasan Çelebi, but really there were problems with both the Ming Dynasty Astronaut and Lagâri Hasan Çelebi's vehicle, even beyond the propellant question.

The Ming Dynasty Astronaut's "vehicle" was said to be a throne. It was going to flip over and smash even if it didn't explode. Lagâri Hasan Çelebi's vehicle is pretty sketchy in description, but generally is agreed to be a sort of open-topped barrel-type thing... which is neither aerodynamic, nor air-tight, and he was supposed to stand in it so even more unstable there. So both are (as originally told) pretty mythological (Çelebi's "parachute" is about as plausable as Icharus' wings too) even assuming modern motors.

The mythbusters used modern motors for both tests, btw, because of health-and-saftey concerns, not that this stopped the Ming Dynasty Astronaut test from exploding - they were not made to be packed in something like a 16x16 grid under a wooden throne with basically-simultaneous ignition.

Both stories, however, highlight the problem that the rockets are really only one of the problems that a TL 4-ish astronaut is going to struggle with. You need an aerodynamic stable body that isn't going to just flip over in flight, you really want to have some control over it beyond "light the fuse and pray to the deity of your choice", it has to be air tight, and you need to somehow bring enough air that your crew doesn't promptly suffocate (or you need a chemical air scrubber, which is even more technology and weight).

Re: [Spaceships] Black powder Rockets?
 

Speaking as a long time Kerbal Space Program player, those can all be solved with more struts and/or boosters.

Re: [Spaceships] Black powder Rockets?
 

BP rockets are low enough temperature that you could structure your system with the payload behind the rocket. Still an explosion risk, of course, but not dynamically unstable.

Re: [Spaceships] Black powder Rockets?
 

If you mean a pendulum rocket, unfortunately those are no more stable than conventional layouts. The force of the rocket is fixed along the axis of the rocket rather than the axis of gravity (As we would usually think of a normal pendulum), so it provides no correcting force.

Re: [Spaceships] Black powder Rockets?
 

Hm. It should still make a difference for atmospheric flight, though yeah, I see the error now.

Re: [Spaceships] Black powder Rockets?
 

It shouldn't be any different in atmospheric flight unless putting the engine in the front also results in the rear having more drag than the front, but that's the same case for a rear-driven rocket.