The Next Generation of Human Spaceflight

[DeltaV]

That's what I said.

I think GW is suggesting to roll just the rudders and intakes, not the entire vehicle, which is why he (rightly, in my opinion :D) called it an oddball idea.

I see. Perhaps just roll everything aft of the crew cabin. It would need a symmetrical cross section at just one body station, a big rotary bearing, and a joint seal and electrical connections that are tolerant of rotation. Doable.

[GW Johnson]

If you can solve the seating problems, just roll the vehicle. Simpler, lighter, more room inside. No heat shield penetrations. Maybe you roll only the crew cabin inside the vehicle.

Visibility is another matter. Cameras might be better than actual windscreens, due to the vulnerability of windscreen materials to hypersonic aeroheat.

Dunno. Just an oddball idea.

[rjaypeters]

As part one of the hypersonic programs (NASP?), someone tried to convince pilots synthetic vision (in lieu of windows) would be sufficient. It was a tough sell.

I like these ideas. If we us an automated vehicle, cabins and windows become superfluous.

Crewed vehicle: Perhaps the simplest idea: seats and control stations that rotate for each flight phase (from 93143)? Pilots claim to need windows and downward facing windows might be an advantage for landing.

93143: I admire your ambition with the radiator for high-ISP deep-space work. May we please just get to the edge of the gravity well, first?

[krenshala]

May we please just get beyond the edge of the gravity well, first?

Fixed that for you.

I count LEO as the "edge" of the gravity well, and we haven't gone beyond it in any meaningful way (from the point of view of this thread) since the Apollo missions.

[GW Johnson]

Reentry windshield designs are a really serious issue. That was the mechanism of flight deck crew death on Columbia's last flight.

Wind tunnel tests that I participated-in as a graduate student, identified the vulnerability of the shuttle design to reentry windscreen failure. There was a very narrow window of pitch angles in which a jet of hypersonic air did not cling to the nose and strike the windscreen. That jet was pinned there by vortices along the sides of the nose.

Between 20 and 40 degrees angle of attack, the hypersonic jet would jump off the dorsal surface of the nose, and thus jump over the cockpit roof and windscreen, leaving them in the subsonic hypersonic wake zone, where they could survive. At all other angles, with the jet striking the windscreen, overheat failure occurs within seconds. So, attitude control is supremely critical during reentry if you have a windshield.

We knew this from those wind tunnel tests in 1973.

Columbia tumbled when she lost her wing at the Texas-New Mexico border. Seconds later, the windscreen caved in. The air blast ripped the flight deck crew to shreds in their seats, and seconds later stripped the entire flight deck roof off the vehicle. The mid-deck crew survived reentry down where there were no windows to fail. They died minutes later of blunt force trauma when the cabin crushed from the buildup of wind pressures, at around Mach 1 / 20 kft, near Tyler, Texas.

The same vulnerability is built into any winged reentry craft with a pointy nose, that also has a windshield you can look out of. There are no transparent heat shield materials at this time in history. Cameras that can be popped out of a hatch or cover, after the hypersonics are over, for landing view actually do make a lot of sense. Pilots do not like that idea, but that is a prejudice, not a justifiable reason.

The other option is to cover the windshield with a heat shield, and remove or stow that heat shield after reentry. Of course, you cannot see out during ascent, unless you have some sort of retractable heat shield design. That would be quite voluminous and heavy, where space and weight are at a premium in design.

So, a set of small retractable cameras with great big viewscreens in the cockpit, actually make a great deal of sense for the designer. It gets down to what has higher priority, logic or prejudice.

Don't get me wrong. I want pilots in any flight vehicle, no matter what kind of automated flight controls might be involved. I trust humans over computers any day of the week. And I know that they have to see what they are doing. It's just that artificial vision makes more sense in a reentry vehicle design.

By using redundant cameras, the equipment failure blind spot problem can be solved. And by use of multiple camera locations, a better view can be made available than could be had through any reentry-compatible windshield we could build.

[GIThruster]

It's just that artificial vision makes more sense in a reentry vehicle design.

It makes sense in almost all vehicle designs, starting with submarines, tanks, APC's all aircraft and especially all spacecraft. Once you leave the Earth's magnetosphere, you have real radiation hazzards to cope with and windows are a serious problem. Since you can have much better vision without the windows, why make them an issue? You don't even need big heavy view screens--you can use simple light-weight head mounted displays and build a powerful interface that allows each wearer to control what they see very quickly and intuitively. They can even see through the spacecraft to land it easily.

Where's the problem here?

[Brian H]

...

So, a set of small retractable cameras with great big viewscreens in the cockpit, actually make a great deal of sense for the designer. It gets down to what has higher priority, logic or prejudice.

Don't get me wrong. I want pilots in any flight vehicle, no matter what kind of automated flight controls might be involved. I trust humans over computers any day of the week. And I know that they have to see what they are doing. It's just that artificial vision makes more sense in a reentry vehicle design.

By using redundant cameras, the equipment failure blind spot problem can be solved. And by use of multiple camera locations, a better view can be made available than could be had through any reentry-compatible windshield we could build.

Remember that cameras can use pinhole lenses, or probably even smaller. It should be possible to put near-microscopic camera viewports in the structure of the heatshield.

[GW Johnson]

Pinhole cameras. Hmmm. Very interesting idea. As long as the leak through the pinhole aperture does not admit flow. Pinhole leaks in heat shields tend to get quite a bit bigger very quickly, if flow through the pinhole can occur. It can be designed-out, but you have to worry up front.

[DeltaV]

Synthetic diamond camera lenses. Excellent heat conductor. If they are small enough and recessed below the boundary layer, passive cooling via heat sinks might work.

Or maybe diamond optical fiber arrays with image reconstruction via Fourier optics.

[rjaypeters]

Excellent ideas for synthetic vision, everyone. Whatever direction you collectively decide to go, try to make the technology as passively safe as you can. Are retractable cameras passively safe?

I tried to find the FAA airworthiness regulations about pilot visibility before posting, I think they will have some bearing.

[D Tibbets]

Glass windows may be vulnerable, but how about aluminum windows? Actually, I believe an aluminum oxide ceramic can be made transparent, or at least they are trying to develop them for armored vehicles.

And as for video interfaces and control inputs, why not a direct cortical link up? It is used in numerous Sci. Fiction stories, though I admit that might be away down the road. Actually, there is an increasing number of pilots that control (with computer assistance) the flight of drone aircraft via video cameras and synthetic displays. It would really be no different than flying IFR (?), er... the opposite of VFR conditions.

And, if remote communication with reentry vehicles can be maintained, pilots on the ground could guide the craft-
"Attention passengers, please fasten your seat belts, your pilot just returned from McDonald's, and is now ready to guide you to a safe landing. We hope you enjoyed your flight with....."

Dan Tibbets

[AcesHigh]

it seems that Reaction Engine´s Skylon design gained some press these last weeks (saw it at physorg.com and at a major brazilian internet portal)

http://www.physorg.com/news204262895.html

apparently, the english government is looking forward to finance the project, and Reaction Engine started producing the revolutionary heat exchanger pieces that are the basis of the SABRE engine.

[Betruger]

Have you, or anyone else, seen any details or clues of that UKSA design review's conclusions?

[Brian H]

...

And, if remote communication with reentry vehicles can be maintained,
...
Dan Tibbets

That's asking rather a lot, considering the plasma fireball that surrounds anything hitting the atmosphere at thousands of MPH!

[GIThruster]

This is why you want M-E thrusters. You not only get a "one gee solution" to anywhere in our planetary system, you get "slow in amto, fast in space". You can break to subsonic before reentry if you like and there's no thermal load on the craft--just what's needed for airline like operations, like flying to the Moon 3X/day with the same craft.