Crew vehicles discussion

Ad Astra · 2005-04-06 06:12:23

The best thing I can say about a lifting body spacecraft is that it can bring its crew back home with minimal reentry forces. That being said, you pay a huge weight penalty for that luxury. It's also possible to do a semi-lifting re-entry with a capsule, mitigating the lifting body's benefits.

An HL-20 type design will be needed for orbital space tourism, but a capsule will be fine for professional astronauts who are in peak physical condition and are able to handle reentry stresses. It's also the most efficient vehicle for travel beyond low earth orbit.

The biggest obstacle towards fielding a lifting body is the low-speed handling problem. To my knowledge, ths has never been solved. Even the X-38 parafoil landing would have been tricky at best. I've given thought to simple swing wings, or perhaps fins that would fold out to become wings at low speed. Both of these options add dead weight, and the folding fins create another challenge for the TPS.

Perhaps John Becker was right when when he said that the benefits of lifting bodies are exaggerated, and winged vehicles are superior.

GCNRevenger · 2005-04-06 08:53:14

"This has always sounded like a White House PR flack's idea (basically the entire "Bush Space Plan" in a nutshell), with little or no engineering or aerospace merits."

Well gee, now how could anybody possibly misconstrue something like that? My usual response is, would you be extolling the virtues of JFK (John Kerry) reincarnate about his grand vision for a return to the Moon if he proposed the same thing?

The basic tenants of VSE are completly technology-agnostic: Return to the Moon is about as general and nonrestrictive a goal as possible. Therefore, I conclude that you don't like VSE because Bush proposed it, ignoring the fact that it completly rewrites NASA's itenerary for the next 20 years after the ISS is done, and forces NASA to change the way it thinks after 30 years of stagnation and status-quo.

"but there was alot of good sensible work done on it (HL-20)"

I was just illustrating how this is simply not the case. Most of the HL-20 fan-club people point out the pretty pictures as a visual illustration to reinforce their position that the HL-20 was "almost done' or something when those "evil, stupid" NASA execs pulled the plug.

My main point is that the development of a reuseable mini-spaceplane will be considerably more espensive then a enlarged copy of Apollo or Gemini, and you won't save as much money as Robert would like it to, such that a capsule doesn't cost more for a reasonable number of flights. The worthlessness of the ISS does not justify it either.

"the all-up weight was just over ten tonnes"

Oh, and thats not quite true. The booster adapter, 8G escape motors, and the HL-20 OMS fuel/water/payload are not included in this figure.

"I also don't like the concept of taking the crew launch vehicle -something specifically built to assure crew safety throughout launch, orbit, and landing- out of LEO. That's one of my doubts about the "CEV" multi-use crew vehicle. Stick with LEO and launch safety, and don't try ramming it into the atmosphere at interplanetary transfer velocities.
That was another of my first points I wanted to discuss here: is there any sense in designing one vehicle to be adaptable to do all that, when what we need is a safe crew space launch vehicle?"

Why not? Pushing it out of Earth orbit is just the same as pushing it to higher or lower orbits around Earth as far as the vehicle is concerned. Its just a matter of fuel and supplies.

And capsules have proven their reliability to reenter at high velocities just fine, and has succeeded every single time without failures.

If we can make the crew launch vehicle perform double-duty as an orbit-to-orbit crew carrier, why not use it?

Palomar · 2005-04-06 09:09:28

Perhaps John Becker was right when when he said that the benefits of lifting bodies are exaggerated, and winged vehicles are superior.

*Um...(tip-toeing into forum because this isn't a strong-suit topic for me)...

I always associate lifting bodies with going out of LEO (Saturn V) and winged vehicles with LEO missions (shuttle or proposed space tourism plans).

So how could one be better than the other? Different means for different purposes -- ?

I'll keep reading in this thread. Perhaps there's an element I missed during the first skim-through.

--Cindy

BWhite · 2005-04-06 09:11:10

Rand Simberg (a very pro-Bush person) recently gave an extremely apt description of the VSE as set forth on 14 January 2004:

Lets just kick the can down the road a little bit. . .

IMHO? Exactly! A spot on characterization.

= = =

Merely going in circles in LEO is unacceptable.

Bravo! We all agree with President Bush on this.

Moon, then Mars, then beyond.

Grumble, quibble, whine, but then well, okay, I guess. Leaving LEO is sufficient reward.

How do we do this?

Come back in 2009 and ask the next President. You see, I just kicked the can down the road and its not my problem no more.

clark · 2005-04-06 09:14:43

Right Bill, because the President saying we are going tommorow, without the capability or experience, makes a whole heck of a lot sense.

Using your analogy, he kicked the can. He set it in motion. That's all he could do. But remember, he didn't even have to do that.

BWhite · 2005-04-06 09:17:31

As far as I can see the creation of Lox from insitu lunar or martian regolith is going to be a show stopper unless the power sources required can be created.

Solar powered pyrolysis will outgas O2 from lunar regolith without major capital investment.

Less efficient than other techniques from a chemical engineering pespective but VERY efficient from an accountant's pespective.

Use inflated gossamer mylar mirrors (cheap & lightweight which holds down launch costs) and then merely heat the regolith in a sealed box until the O2 outgasses.

Edited By BWhite on 1112800668

BWhite · 2005-04-06 09:23:38

Right Bill, because the President saying we are going tommorow, without the capability or experience, makes a whole heck of a lot sense.
Using your analogy, he kicked the can. He set it in motion. That's all he could do. But remember, he didn't even have to do that.

Yup. And he deserves credit for doing that. Now, NASA and Congress must fashion the next step.

= = =

David Halberstam wrote a great line about Jerry Krause, general manager of the Chicago Bulls during their repeat three-peat era. Krause was jealous of the attention Michael Jordan received and would assert that he (Krause) was the real hero of the Bulls success.

Halberstam wrote (paraphrased):

By seeking more credit than he deserevd, Krause merely assured that he would get less credit than he deserved.

President Bush deserves credit (and praise) for 14 Jan 2004. But how much credit? And we now face countless "now what?" questions.

= = =

Last spring, clark, you told us (me) to await the Aldridge report.

Okay. its been out for a while. Now what? :;):

Edited By BWhite on 1112801107

SpaceNut · 2005-04-06 09:28:36

Yes ;Solar powered pyrolysis will outgas O2 from lunar regolith without major capital investment.

But the problem then is concetrating it under pressure and cooling it to liquify it. If we can not do that with the waste hydrogen from the ISS oygenation unit, then how will we get over that same hurdle on the moon.

As for the adridge report some thing are or have been set into motion like in the down sizing of some Nasa facilities, getting rid of non space function and Hopefully there will be more.

BWhite · 2005-04-06 09:35:49

Yes ;Solar powered pyrolysis will outgas O2 from lunar regolith without major capital investment.

But the problem then is concetrating it under pressure and cooling it to liquify it. If we can not do that with the waste hydrogen from the ISS oygenation unit, then how will we get over that same hurdle on the moon.

If there is not enough heat, send more (larger) mylar mirrors. 100 kg of mylar film will be sufficient for a rather huge mirror. Not enough? Try 500kg of mylar film. Even at $10,000 per pound to LEO an extra 500 kg of mylar will be a tiny fraction of the total mission budget.

Once you have gas phase O2 in the collection box, cool it and compress it.

I would cool it by pumping the gas into a new box positioned in lunar shadow, and only then mechanically cool it and run the compressors.

Waste heat from the slag can be used to run Sterling cycle engines. Inefficient, but with a box of hot lunar rock to dispose of, might as well extract something else useful.

= = =

Okay, the engineer types will have some work to do. But if we cannot do something this simple and essential - - why bother going at all?

Edited By BWhite on 1112801928

Grypd · 2005-04-06 09:42:32

Yes ;Solar powered pyrolysis will outgas O2 from lunar regolith without major capital investment.

But the problem then is concetrating it under pressure and cooling it to liquify it. If we can not do that with the waste hydrogen from the ISS oygenation unit, then how will we get over that same hurdle on the moon.
As for the adridge report some thing are or have been set into motion like in the down sizing of some Nasa facilities, getting rid of non space function and Hopefully there will be more.

The concentrating of the Oxygen could be done by pumping it to one of the permanently black areas of the Lunar poles and allow it to cool to form an ice. This also solves the storage problems.

When it is required for Fuel etc it can then be heated up and pumped back. And as these poles are a prime science and resource target then it is probable that many missions will go there and we can use it as our foothold and staging areas.

clark · 2005-04-06 09:59:53

Last spring, clark, you told us (me) to await the Aldridge report.
Okay. its been out for a while. Now what?

Now what, what?

NASA gets funding boost while non-military gets slashed. NASA gets revamped. NASA works out how to retire the SHuttle. NASA submits CEV specs in May.

You wait. Just enjoy the ride.

Seriously, do your own kids ask, "are we there yet," as much as you?

SpaceNut · 2005-04-06 10:25:02

It is great that we can solve outside of the box for the lunar creation of not only oxygen to breath but also for making LOX on the moon from regolith. To be used in rocket propulsion.

Now onto how can we do the same on mars economically as well is the next question?

As mention not much news coming out about the CEV design or build. Only a little more on the team make up from the Boeing, Northrop camps attempt as posted in the cev catch all thread.

BWhite · 2005-04-06 10:26:49

Last spring, clark, you told us (me) to await the Aldridge report.
Okay. its been out for a while. Now what?
Now what, what?
NASA gets funding boost while non-military gets slashed. NASA gets revamped. NASA works out how to retire the SHuttle. NASA submits CEV specs in May.
You wait. Just enjoy the ride.
Seriously, do your own kids ask, "are we there yet," as much as you?

Yup.

And in a few years Keith Cowing will report that NASA is the same as it has always been. More same old, same old. ??? :;):

BWhite · 2005-04-06 10:31:53

It is great that we can solve outside of the box for the lunar creation of not only oxygen to breath but also for making LOX on the moon from regolith. To be used in rocket propulsion.
Now onto how can we do the same on mars economically as well is the next question?

Lunar LOX is easy, IMHO.

Water? There may not be any but that means we just use methane for rovers and for launching from Luna etc. . .

Heck, combust methane in a Honda generator bought at Home Depot and pure water will gush out the exhaust. Tune your rovers poorly and collect the CO for the carbonyl process to extract Fe and Ni from regolith.

Use methane rather the LH2 beacuse it can be stored and shipped in much smaller tanks than LH2 and less should be lost during long term storage. And it provides CO for carbonyl (Mond) processes. And CO2 for greenhouse experiments.

= = =

GCNRevenger says "NO" - - but I still ask why wouldn't water ice and dry ice rain or snow on the lunar surface underneath the launching pad used to send a methane/LOX rocket back to Earth?

If a crew remains on the Moon after a rocket leaves with cargo, why not scoop up the water ice for re-use?

Edited By BWhite on 1112805296

GCNRevenger · 2005-04-06 11:29:37

GCNRevenger says "NO" - - but I still ask why wouldn't water ice and dry ice rain or snow on the lunar surface underneath the launching pad used to send a methane/LOX rocket back to Earth?
If a crew remains on the Moon after a rocket leaves with cargo, why not scoop up the water ice for re-use?

Trouble is Bill that the exhaust plume will spread out really far, and just about none of the exhaust will come back down near the launch site.

Remember that the Moon has only 1/6th gravity, so the stuff has much more time to spread out before Lunar gravity pulls it to the ground.

BWhite · 2005-04-06 11:37:43

GCNRevenger says "NO" - - but I still ask why wouldn't water ice and dry ice rain or snow on the lunar surface underneath the launching pad used to send a methane/LOX rocket back to Earth?
If a crew remains on the Moon after a rocket leaves with cargo, why not scoop up the water ice for re-use?
Trouble is Bill that the exhaust plume will spread out really far, and just about none of the exhaust will come back down near the launch site.
Remember that the Moon has only 1/6th gravity, so the stuff has much more time to spread out before Lunar gravity pulls it to the ground.

Hmmm. . .

Makes sense. Too bad. ???

Okay, land and launch from inside a crater and build a "snow fence" around the top rim. What percentage of the fuel is combusted even getting 10 meters off the ground?

GCNRevenger · 2005-04-06 13:32:36

Since there is no atmosphere and the gravity is low, you'd want to pitch over and start building up tangential velocity about as quickly as you safely could with the thrust available.

Translation: You would not spend more then seconds over the launch site... So basically, if your burn lasted many minutes, almost none of the exhaust would fall within the crater.

Plus, since the stuff is not buried, it could get burned off and sublimbed when the sun hits it, and it would be gone and not stay neatly trapped in the dirt under the dust, protected from the sunlight.

GCNRevenger · 2005-04-06 13:55:43

Anyway, I would like to reiterate that instead of spending big money on a new mini-spaceplane when development dollars are at a major premium, we ought to stick with capsules since they are cheaper to develop, lighter, and proven. Then, when we need reuseable transport from Earth to LEO, we build Shuttle-II, and skip any intermediate mini-Shuttles.

dicktice · 2005-04-06 14:51:55

I'm all for intermediate "walk befor you run" develpment, especially if it'll make routine crew transport possible soonest. The next question is where do we land them?

RobertDyck · 2005-04-06 15:01:39

I always associate lifting bodies with going out of LEO (Saturn V) and winged vehicles with LEO missions (shuttle or proposed space tourism plans).

Hi Cindy. Lifting bodies are for atmospheric flight. You don't need any aerodynamic stuff in space, they're only for re-entering the atmosphere.

The biggest obstacle towards fielding a lifting body is the low-speed handling problem. To my knowledge, ths has never been solved.

All lifting bodies have handling problems at a specific speed range. The genius of HL-20 is that it's handling problem is between mach 2.0 and 0.9 so that occurs miles up in the air where the only thing you can collide with is a cloud. It handles fine at low speed where its important, so you touch down softly and wheels first.

Perhaps John Becker was right when when he said that the benefits of lifting bodies are exaggerated, and winged vehicles are superior.

A lifting body maximizes internal volume while minimizing surface area. That's great in space where the surface area is useless. It also minimizes TPS area so reduces heat shield mass. A lifting body actually handles much better than wings during hypersonic flight, such as first entering the atmosphere where you need the a heat shield.

"the all-up weight was just over ten tonnes"
Oh, and thats not quite true. The booster adapter, 8G escape motors, and the HL-20 OMS fuel/water/payload are not included in this figure.

Actually, according to Encyclopedia Astronautica the dry mass of HL-20 was 10,884 kg (10.884 tonnes) but the launch mass was 25.9 Klb (16,284 kg). The escape motors were internal so did come back, they are included in the dry mass; but fuel, cargo and crew weren't.

I keep asking why you would want to drag atmospheric entry systems all the way to the Moon and back, or even to Medium Earth Orbit. Leave them in LEO where they're close to the atmosphere, and use a dedicated in-space vehicle to travel farther. A capsule is lighter than a lifting body, which is lighter than a winged orbiter, but the problem with a capsule is it isn't reusable. But again why would you want to drag even a capsule farther than LEO? A capsule has a titanium hull because only the bottom is protected by an ablative heat shield. You could build a capsule of aluminum if you covered the upper part with DurAFRSI, but either way it's added weight. Then there's the parachutes, floatation bags (Apollo) or landing rockets (Soyuz), survival gear and added structure for stresses of high-G entry. Isn't it better to leave all that parked in LEO and take a dedicated vehicle to the Moon?

GCNRevenger · 2005-04-06 15:42:00

"I keep asking why you would want to drag atmospheric entry systems all the way to the Moon and back"

Answer:
#1: So you can abort directly to Earth if something goes wrong and not have to wait to synchronize orbits, rendevous, and dock if you need to get back down right now.
#2: Its easier and quicker since that method is proven. If you are aiming to contest that this isn't worth future operating costs being somewhat higher, then I would disagree with you. NASA needs results, on budget, and sooner rather then later.

"The escape motors were internal so did come back, they are included in the dry mass; but fuel, cargo and crew weren't."

No they wern't, the escape motors are not reused. They flank the booster adapater just under the vehicle. This adapter is the big "hidden fine print" mass cost, and it weighs several thousand kilograms. I think that its safe to say that HL-20 would have a hard time meeting the 20,000kg limit fully-loaded, since there is little margin for weight creep.

A lifting body maximizes internal volume while minimizing surface area"

Capsules maximize it better.

Ad Astra · 2005-04-06 16:01:09

Obviously, lifting bodies fall in between winged vehicles and capsules in terms of their capabilities. Capsules have better volumetric efficiency and heat rejection properties, while winged bodies have lower-stress reentries and better handling capabilities at low speed.

The lifting bodies were supposed to bridge the gap between the two; the point John Becker tried to make is that the heat-rejection and volume advantages claimed by lifting body proponents were greatly exaggerated. He much preferred winged bodies for LEO to earth transportation.

Many of the claimed drawbacks of capsules are just plain incorrect. Capsules can be reusable, as Gemini II proved, and Super Soyuz (Zarya) tried to validate. They can also be optimized for in-space transportation. You want a lighter capsule for transferring people between LEO and the moon? Build your basic earth-to-LEO capsule, but take off the heat shield and substitute lighter components wherever possible. You'd have to launch it unmanned and transfer to it from your earth-to-LEO capsule, but you'd save mass nonetheless.

GCNRevenger · 2005-04-06 16:06:28

Exactly Bill. I don't see any reason why a capsule can't be reused as long as it dry lands. Harder to reuse then a small spaceplane sure, but not impractical. Some componets of Soyuz-TMA are reused today.

And for the Lunar acent vehicle... if you aren't planning on riding down in your TransHab, then the capsule itself could be used for the decent crew module, and save you a whole spacecraft in return for a little larger decent/acent fuel. Or as you suggested, build a copy and omit the heat shield and parachutes, so again, you only need to design one vehicle.

RobertDyck · 2005-04-06 16:40:44

"I keep asking why you would want to drag atmospheric entry systems all the way to the Moon and back"
Answer:
#1: So you can abort directly to Earth if something goes wrong and not have to wait to synchronize orbits, rendevous, and dock if you need to get back down right now.

You have the atmospheric vehicle with you during launch, you can abort and get down right now anytime. You would only transfer to the LTV after successful stable orbital insertion. In fact, you have to rendezvous and dock to make the transfer. If you run out of power or oxygen during return to Earth, you can rendezvous with ISS. We have a space station, it is the safe haven. There are people who argue it was a waste of money, but that doesn't matter now; we have it so use it. In fact, leave the atmospheric descent vehicle (lifting body or capsule) docked with ISS.

#2: Its easier and quicker since that method is proven. If you are aiming to contest that this isn't worth future operating costs being somewhat higher, then I would disagree with you. NASA needs results, on budget, and sooner rather then later.

Ohhh, the "easier quicker" argument. America was able to develop a Moon vehicle in the 1960s when no one had done anything like that before. Has America lost that? Was the only reason America could in the '60s due to competition? Does America need a firm kick in the pants to accomplish anything?

Or from another perspective, the current Shuttle was the option with low up-front development cost. That also had its reasons; NASA needed results on budget and sooner for fear they would be out of the space business. The result of that rush was a vehicle that now costs roughly $540 million per launch including amortized fixed costs, and only flies 6 times per year. Don't repeat that mistake, do it right this time.

::Edit:: Correction, the Shuttle budget for 2005 is $4,543.0 million, including return to flight and scheduled flights for May and July. Future flight dates are under review. Due to return to flight work, it's hard to estimate a per-launch cost. The Shuttle budget for 2006 is $4,530.6 million so assuming they get back to 6 flights per year that will be an average of $755.1 million per launch.

Grypd · 2005-04-06 17:31:08

"I keep asking why you would want to drag atmospheric entry systems all the way to the Moon and back"
Answer:
#1: So you can abort directly to Earth if something goes wrong and not have to wait to synchronize orbits, rendevous, and dock if you need to get back down right now.
You have the atmospheric vehicle with you during launch, you can abort and get down right now anytime. You would only transfer to the LTV after successful stable orbital insertion. In fact, you have to rendezvous and dock to make the transfer. If you run out of power or oxygen during return to Earth, you can rendezvous with ISS. We have a space station, it is the safe haven. There are people who argue it was a waste of money, but that doesn't matter now; we have it so use it. In fact, leave the atmospheric descent vehicle (lifting body or capsule) docked with ISS.
#2: Its easier and quicker since that method is proven. If you are aiming to contest that this isn't worth future operating costs being somewhat higher, then I would disagree with you. NASA needs results, on budget, and sooner rather then later.
Ohhh, the "easier quicker" argument. America was able to develop a Moon vehicle in the 1960s when no one had done anything like that before. Has America lost that? Was the only reason America could in the '60s due to competition? Does America need a firm kick in the pants to accomplish anything?
Or from another perspective, the current Shuttle was the option with low up-front development cost. That also had its reasons; NASA needed results on budget and sooner for fear they would be out of the space business. The result of that rush was a vehicle that now costs roughly $540 million per launch including amortized fixed costs, and only flies 6 times per year. Don't repeat that mistake, do it right this time.

What we have is an ISS in the wrong orbit for use as a waystation to the Moon or further. This was done so the Russians could get on board this was a political decision and it . It was also political decisions that made the ISS into the not very useful plan it is now and with each redesign it becomes more nad more a financial mistake. What we also seem to have is an unfinished ISS that may not survive until the shuttles replacement can fly it is a creaking, power failing, No stability, Poor enviromentals mess. And im not actually sure what real science potential it has.

The Shuttle was another example of politics over sense the shuttle was designed the way it was to meet everyones needs. It went rapidly over budget from the almost completely reusable design first envisioned and with each redesign more nad more weight was put on. The original shuttle would have been a lot smaller man only no cargo vehicle that would have paved the way to cheaper flight. It would have been a lot safer as it would have not had the solid rocket boosters which Von Braun noted should never be used to transport people. It would have had the actual shuttle located on the top of the rocket and its very vulnerable heat shield well protected from debris. Even the Airforce one of the reasons it cost overan and piled the pounds on pulled out when they saw the monster it was becoming.

In the early 70s the USA could have had a small reusable shuttle for launching crew and a variety of cargo launch rockets to transport cargo. This would have kept the mighty Saturns and they would have been improved on. Space access would have been cheaper and the Moon would already have a base on it.

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