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July 10, 2011
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Home in Sight by Eagle1Division Home in Sight by Eagle1Division
Part of my RTLS abort. [link]
It's not a space shot... But it still looks way, way, waaay better full-screen! :D

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I came in a bit too high, so I had to circle around, and now I'm lining up for my final approach to Kennedy. It's a sweet, calming sight. Every flight lands like this, so the perilous abort is mostly over.

But, a landing like this is far from calm or ordinary, even though it is routine for Shuttle flights. It's a 109 ton glider the glides about as well as a brick. I can't come in too fast, or I'll run out of runway and smash the shuttle up. Even if I survive such a crash, the toxic OMS (Orbital Maneuvering System) propellant tanks will most likely be ruptured.
But if I come in too slow, I've dropped the external tank, the only fuel tank, for the main engines, and the Orbital maneuvering engines not only spout out toxic chemicals but they don't have enough thrust to do anything in-atmosphere, even if they could work in the atmosphere. So I can't recover any lost speed.

I've got to get the approach perfect. The speed just right, the altitude just right, the speed right for the altitude, and most of all the distance to the runway right for speed and altitude.

Anything but ordinary.

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:iconhellcatf6f:
HellcatF6F Featured By Owner Jul 20, 2011   Digital Artist
The shuttle was expensive, cluttered by inefficient bureaucracy, but it was the first and only reusable spacecraft ever built. I hope that somehow a true SSTO (Single Stage to Orbit) gets developed.

An SSTO can be done with either the right materials (carbon nanotube structure and silica aerogel thermal protection) or nuclear thermal rockets (NERVA was successfully static fired).
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:iconeagle1division:
Eagle1Division Featured By Owner Jan 23, 2012  Hobbyist General Artist
Not too long ago I read up on the DC-X. You might want to give it a look. NASA dropped it in favor of the horizontal shuttle-like landing ill-fated Venture Star.

But the DC-X was actually incredibly successful. It probably would've worked.

It failed when they used a Russian-imported oxygen tank that had sub-standard welds. The DC-X test vehicle had previously survived engine explosions, etc. But this time it landed, fell over, caught on fire, no major damage, except the sub-par oxygen tank ruptured, causing the flame to grow hotter and total the vehicle.

NASA could've easily built a new one, but decided to use funding on Venture Star instead.

Read about it on wiki. It's a fascinating story.

But, quick note, it seems SpaceX has a better idea: all the reusability advantages of an SSTO, without the technical challenge. Youtube "SpaceX reusable", the video is pretty accurate.
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:iconhellcatf6f:
HellcatF6F Featured By Owner Jan 24, 2012   Digital Artist
I just read about the DC-X. One thing that really stands out is its robustness, able to survive engine explosions and other damage and still land safely. I never knew Jerry Pournelle was involved in its design either. He is a great sci-fi author and solid conservative.

I also watched the Space-X video. The DC-X would be a good design for a nuclear powered SSTO. For chemical rockets, Space-X is better.
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:iconeagle1division:
Eagle1Division Featured By Owner Jan 24, 2012  Hobbyist General Artist
I'm on the laptop ATM, but later I'll get on the desktop and try a little experiment: I've got a spreadsheet for calculating vessel mass, I'll try taking a space shuttle external tank and 1.4x the weight/thrust ratio of the SSME's (to account for structure mass and heavier, reusable engines), and see what payload it can take to orbit, if any. Just a neat little experiment to get an idea of how difficult SSTO is. But from what I've read, it seems the DC-X was doing very well.
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:iconeagle1division:
Eagle1Division Featured By Owner Jan 24, 2012  Hobbyist General Artist
Hmm. I think NTR would be more expensive, though, because of all the work needed to safely work with a nuclear core. Not to mention radioactive exhaust.

Also I think it depends on how reusable SpaceX's rockets would be. Staging allows for heavier components, which might prove to be an advantage in price.
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:iconeagle1division:
Eagle1Division Featured By Owner Jul 20, 2011  Hobbyist General Artist
Oh, btw, thanks for commenting so thoughtfully! :D
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:iconeagle1division:
Eagle1Division Featured By Owner Jul 20, 2011  Hobbyist General Artist
Aye, yet I still think the STS was the most amazing machine ever built by man. But the NASA of today isn't the NASA that put men on the moon.

Nuclear thermal has an extremely hard time with T/W ratio. While the SSME's had a T/W ratio of 73, NERVA, IIRC, had an extremely difficult time getting higher than 1.

One interesting concept I've seen is using a large microwave-absorbent under-surface of the vehicle, hitting it with a microwave laser, the heating expands hydrogen propellant, giving thrust.

Really, though, any engine system that manages to deliver the needed impulse AND thrust for an orbital vehicle will almost certainly be very complicated and expensive.

The only way to make space access truly routine, in the nearest term future, is with non-rocket spacelaunch, such as an orbital elevator. You mentioned carbon nanotube structures: a carbon nanotube wire.
It would be huge, super expensive, probably an international joint effort, but far more reusable and maintainable than any conceivable rocket lift system with any engine. That would make space access the most routine.

All this said, though, I don't think that an SSTO is quiet as impossible as it's made out to be. One thing that kind of disconcerts me is the choice of LOX/LH2 propellent for the Venture Star. I'd like to see them look into LOX/RP-1, lower specific impulse, but RP-1 is far, far, far denser and easier to store than LH2, which means a much higher mass ratio is possible.

Also, If I'd have to guess, I'd say the Venture Star met it's fate more due to NASA's inefficient bureaucracy than technical issues. For instance, with a much lower mass, the Dragon spacecraft by SpaceX can carry 7 astronauts instead of Orion's 4. With a lower mass. I'd like to see private companies look into SSTO's.

I think Venture Star earned SSTO's an undeserved bad reputation...
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:iconhellcatf6f:
HellcatF6F Featured By Owner Jul 21, 2011   Digital Artist
Another way to do an SSTO would be to place the engines up front and have it tow the rest of the vehicle up into space on high strength cables, protected from the engine flame by silica aerogels. Using Robert Goddard's concept would allow for a vast reduction in structural mass with an according increase in mass ratio. The cables could be extended in orbit to either spin the ship slowly for gravity simulation or to act as electrodynamic tethers to use the Earth's magnetic field for power generation, drag compensation and maneuvers without using RCS fuel. For reentry, the engine is reeled in and the base of the ship could expand similar to an umbrella for maximum drag.
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:iconeagle1division:
Eagle1Division Featured By Owner Jul 22, 2011  Hobbyist General Artist
Hmm. Even with that design, I don't really see how it can maneuver without RCS jets. Microdragging is too insignificant to do much. The design sounds very difficult to do in application, in the dynamic environment of Earth's Atmosphere, with all the moving parts and complexity required.

And it wouldn't change things too much... The added advantage would be a "pull" configuration instead of a "push", saving mass on structural support. However, this same mass saving has been done by pressurizing the fuel tanks of rockets. In the early space race, many rockets worked like this. At the KSC visitor center, you can see cables holding the rockets up. They can't support their own weight without the tanks pressurized, but with the tanks pressurized it "inflates" and strengthens the tanks like an inflated balloon.

But, in a vacuum, where you don't need nearly as much added complexity to make it aerodynamic, the idea is a very good one: [link]
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:iconstealthflanker:
Stealthflanker Featured By Owner Jul 19, 2011  Hobbyist Digital Artist
I will miss the Space Shuttle
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