Low Budget Manned Orbital Spaceflight

[Vee]

Few things have lifted my spirits as much as the recent first private manned spaceflights, by Spaceship One.
Mike and Brian proves that true heroes still exist. And Burt Rutan is the sort of legend that delivers.

I really hope I will live to see the day man lands on Mars, or the day private entrepreneurs achieve manned orbital spaceflight.

So meanwhile, I'd like to invite to a discussion about the difficulties to achieve manned orbit, on a low budget.

Let me start off by listing the difficulties I see, for "Tier Two" compared to Spaceship One.
In the order of seriousness, my estimate.

1: Energy level. Reaching orbit altitude and speed requires magnitudes more energy.
Is it possible to scale the type of rocket engine used in Spaceship One, to cope with such energy requirements?
I'm also sort of fantasizing about a "super"-knight, with more powerful jet engines, more of them, maybe water injection.
Swept slender wings for supersonic speed at extreme altitude, carrying the rocket vehicle up to maybe 70,000 feet. Or maybe better? Release at highest possible energy.
Then maybe a transition vehicle, working much like Spaceship One, but no cockpit and remotely piloted on return. This would boost the orbit vehicle into space. The more advanced orbit vehicle would then continue to orbit. Could this succeed?

2: Reentry. Spaceship One dispensed with heat shield, thanks to its light weight and rapid braking. Feathering the wing gave a flat reentry that transfered the energy to shockwaves and turbolence, rather than skin friction and heat. Rapid braking means heavy gees though.
But I also don't think this solution will still work alone, at the much higher energies that a reentry from orbit involves.
Could a combination of accepting as much as 12g for rapid braking, lightweight construction to keep energy down, and some lightweight heatshield, conceivably cope with this problem? Maybe dumping the remnants of the rocket engine to lower weight? (That capability in turn would probably lead to higher structural weight and less safety, though).

# Obviously the key to both 1 and 2 is keeping down the weight.

3: Rocket flight control in space. Spaceship One was flown on the last atmospheric remnants of aerodynamic control, into space.
The simple rocket engine had no thrust vector control, and also produced fluctuating thrust and thrust vector. This launched Mike into a violent spin on the second flight, I believe. Brian then flew a slightly less steep ascent on the third flight, staying a little bit longer in air.
It will not be possible to reach orbit by coasting though. And it is also probably needed to guide and adjust the flight path to orbit.
How complex and expensive will it be to achieve a safe rocket engine that can give guided flight?
I'm thinking along vanes in the nozzle. Would such a simple device work?

Computers shouldn't be a problem, or is it?

4: Precision of reentry. Can reentry be predicted and controlled precisely enough, to allow safe landing on a preselected site?
I think it can. But I'm unsure of the difficulties.

5: Am I missing something?

 

[everman]

Burt and the others at Scaled Composites talked about this briefly in a Discovery channel show about their X-Prize win. Manned orbital spaceflight is a whole different animal.

I believe it is their next goal, and I don't doubt that they can do it too. I'd love to be a passenger on that flight, although now it looks like I really may get to go on something like Spaceship one in 20 years.

 

[imported_Hamzter]

While it's nice to see Burt start off the space tourism business, I don't think orbital flights will be very common for quite a while. An orbital vehicle would be vastly different from Spaceship One, it would have to be alot tougher for a start. A hard reentry is by far the easiest way out of orbit, the only other way is by retro boosters to slow the craft before it hits the atmosphere, it'd still be quite stressful on it though, it'd also mean you'd need to carry alot more fuel with you.

The hybrid engines on spaceship one don't have the energy density required for orbital flight (correct me if I'm wrong), different fuels may be possible while keeping the same design principles though. A bigger and better white knight vehicle would be good though, imo it's the best feature of the system, launching at altitude greatly reduces fuel needed to overcome air friction.

While Burt Rutans business will start off the industry, I'm hoping that some progress is made on space elevators. While crazy, if they work they'll be great for getting into orbit, no complicated rocket systems to worry about and replace, just a 20,000km cable and some mechanical climbers.

 

[Gibsons]

The hybrid engines on spaceship one don't have the energy density required for orbital flight (correct me if I'm wrong)

iirc, spaceship one reaches about mach 2 (?). To go orbital, you need something like mach 25. So they're a looong way from orbital speed and recovery. Very roughly, they'll need an order of magnitude more speed (and therefore energy) and maybe an equivalent amount of heat to deal with on re-entry. Seems quite difficult to me, but then again Rutan seems to be a very clever guy.

 

[Vee]

I thought the speed matched something comparable to Mach3½. But I've no idea where I got that figure from. Mach is really not useful for speeds here anyway, since it is a property that assumes atmosphere and is also a function of atmospheric conditions. We should look up, or calculate the absolute speed of a low eart orbit instead.

Nevermind. If the energy density of the rocket is too low, meaning it's marginal or inadequate for even lifting itself into orbit, then - ouch! That's bad news.

Still, chemical rockets don't vary terribly much in specific energy? Or am I very wrong here?
The Spaceshuttle achieves very good structure and payload weight into orbit, relative to weight of fuel.
Which means that with a very light orbit vehicle, the goal looks achievable?

But a liquid fuel rocket for the orbit vehicle looks like bad news. Expensive and unsafe.

But wasn't Scale Composites involved in some solid boost to orbit vehicle? Pegasus.
I think it has done some 30 launches. Dropped from a Lockheed Tristar carrier aircraft.

Pegasus is able to put some 500lb into low earth orbit. It is released from much lower altitude and initial energy than White Knight provides, not to mention some "Super Knight".
Obviously it carries no means for reentry, and safety is relaxed as it is unmanned.
I'm just mentioning it, offering it as an example of that orbit is indeed achievable with lowcost and easily managed rocket engines.

...- Still, a solid fuel rocket cannot be regulated or turned off. Which seem like bad news.