Design of manned lander

[joema]

...You could argue that by the time it lands, with most of the propellent expended, the CG will be really low as the remaining propellent and the heavy engines are at the end where the thrust is and so making it easier to control.

All future manned aerospace vehicles will be computerized fly-by-wire. Commercial airliners are already there, even cars are rapidly moving that way. Just as the space shuttle could not fly without constant computerized control, future vehicles will be likewise. A computer can land a vertical tail-sitter regardless of where the CG is. Whether the vehicle is inherently stable or not makes no difference.

That said I don't see the advantage of a tall thin rocket, even though computers make it easy to land vertically.

If it was an established planet with people already there, they could build a runway and a winged vehicle could land with no rockets or parachutes, just like the shuttle. However this isn't the most mass-efficient way to reenter and land, if you consider the mass of the wings, landing gear and associated structure. Also the first explorers could probably not land horizontally without a runway.

This leaves parachutes, rockets or some combination. It has been studied extensively for SSTO proposals and rockets vs parachutes are often fairly equal, but there's variation based on configuration specifics. However for a reentering SSTO you have the engines anyway -- you've already paid the mass penalty of getting them to orbit, so the decision is mass of additional fuel vs mass of parachutes. But with a purpose-designed lander, engines aren't already there. Therefore I'd guess parachutes would be the clear winner from a mass standpoint.

With modern computerized guidance a capsule/parachute approach can have precision landing capability. So parachutes no longer imply inaccurate landings.

[danscope]

Why not build a vehicle which gets to orbit, or build it by modules in orbit,then let it take on the fuel it will need to boost towards it's destination. Use a lighter lander to descend by parachute, and re-fuel on the surface for boost into local orbit, rendezvous with the returning vessel to Earth Orbit. Use a shuttle for Earth return.
This solves many problems and offers security.
Nothing is easy. Jethro Tull

[Ara Pacis]

The OP doesn't want to go back to orbit, he wants to fly around the planet. Rockets aren't good for this. A power source, such as nuclear, might help produce fuel that would work inside a more efficient propulsion ICE system like a piston or turbine to turn props. Wings might seem like parasitic waste and not be useful on the descent, depending on desired characteristics of reentry, but they become invaluable for efficiency on aeroflight. Think less of the lander less as Swiss Army knife and more like a Transformer.

[danscope]

Why would he call such a craft a " Lander " if it won't return to the surface of this "earth-like planet " ???

[swampyankee]

Why would he call such a craft a " Lander " if it won't return to the surface of this "earth-like planet " ???

It landed from the orbiting space ship. It's not going back up.

[danscope]

Oh.... a 'capsule ' . We have those .

[Ara Pacis]

Oh.... a 'capsule ' . We have those .

No. a "capsule" is a shape. A "Lander" is a function. Not all landers are capsules and not all capsules are landers. But even if you ignore the semantics, how do you make it (a capsule-shaped lander, if that's your predilection) fly from point to point around the planet, is the OP's question.

[danscope]

Much would be determined by the air-density ( if any) and oxygen( if any ) . Powered blimp is one method perhaps. Wings demand prepared surfaces not always found or available. Pure rocket propulsion is difficult and demands fuel in a big way. And it doesn't last long, my pretty, not long.
Much depends on the nature of the landing , the mission , and the availability of fuel and how much weight one has to lift . Know your target well.Then design for that circumstance. Np question.

[Ara Pacis]

Much would be determined by the air-density ( if any) and oxygen( if any ) . Powered blimp is one method perhaps. Wings demand prepared surfaces not always found or available. Pure rocket propulsion is difficult and demands fuel in a big way. And it doesn't last long, my pretty, not long.
Much depends on the nature of the landing , the mission , and the availability of fuel and how much weight one has to lift . Know your target well.Then design for that circumstance. Np question.

The planet is like earth, also mentioned in the OP.

[danscope]

Why didn't he simple say Earth? And how much material does he need to move from place to place once he lands? Parameters,Sir. Parameters.
The blimp is looking better and better ( but not in winter or icing conditions ) .

[joema]

...Wings demand prepared surfaces not always found or available. Pure rocket propulsion is difficult and demands fuel in a big way....

Exactly right. The previously-shown 2-man lunar exploration rocket (http://www.bautforum.com/showthread....12#post1990912) worked in that scenario for several reasons: 1/6 g, no air friction, very limited payload, and -- fuel was already available (they planned on using residual fuel in LM descent stage).

Scaling that up to a 1 g atmospheric earth-like environment doesn't work, nor would flying the entire vehicle, winged or not. It would be like landing the space shuttle in a remote area and trying to take off again. Given enough propellant, engines (rocket or air-breathing) it would be possible, just not efficient. In fact early shuttle proposals planned on self-ferry capability where they'd strap on jet engines and it would take off and fly back to the Cape. However it was costly, complex and inefficient so it wasn't pursued -- and that was on a developed planet where the additional fuel and engines could be delivered by truck.

Given enough fuel a non-winged powered descent vertical lander like the DC-X could (after landing) take off and fly a short distance, but wouldn't be efficient: http://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X

The requirements for a lander are so divergent from an atmospheric exploration vehicle, it would be much more efficient to have a separate vehicle for that. It could probably be carried within the main vehicle. The OP described a 10-person lander, so it would be pretty big and have additional space for cargo and equipment commensurate with this crew size. Depending on the requirements the exploration vehicle could be a one-man powered parachute, a folding 1-4 person ultra-light winged vehicle, or even larger. For larger cases, a separate equipment-only lander could carry it. In many exploration scenarios, manned landing is preceded by unmanned equipment & supply landers. The OP scenario did not preclude this. Whether wheeled or winged, exploration vehicles are just one type of equipment such unmanned precursor landers could carry.

Whatever the payload/range requirements, we already know from earth experience the most efficient means of atmospheric flight on an earth-like planet. Just examine what vehicles are used on earth for a given situation, and something similar would be used on this hypothetical earth-like planet. It would almost certainly have wings (whether fabric, or folding rigid) and be powered by a small engine (combustion or electric) spinning a propeller or ducted fan.

Antarctic scientists don't do local exploration by flying around on rockets, they use light aircraft. The cost of transporting mass to Antarctica is much less than to another planet, so efficiency would be an even greater concern in that case.

[publiusr]

One thing the Soviets considered was a crasher stage. SLS lunar expeditions may use something similar. This allows for a smaller lander than Altair would have been on Ares V.

MISC:
http://www.nasaspaceflight.com/2011/...lunar-options/
http://www.nasaspaceflight.com/2012/...sample-return/
http://www.nasaspaceflight.com/2012/...ads-potential/

[danscope]

Hi Joema, a well thought out reply. It might be that a lander with many persons on board would use ( for a few reasons) a powered blimp. The hydrogen-filled device could be inflated locally from generated hydrogen , and even burn hydrogen in a piston ( recip) engine , employing a traditional propeller.
Now , you enjoy 'linger' time, selection at will of landing places, flexibility to retrieve objects ( re: food, water etc) providing weather co-operates within
design parameters. Slow, safe and flexible has much to reccomend it.
Best regards,
Dan

[Garrison]

SLS lunar expeditions may use something similar.

I know this is for a sci-fi story but lets try and maintain some reality sense of reality.

[publiusr]

Not for sci-fi. Crasher stages are being discussed over at your other haunt--as you well know
http://forum.nasaspaceflight.com/ind...topic=27446.30
http://forum.nasaspaceflight.com/ind...5960#msg835960

[Garrison]

Not for sci-fi. Crasher stages are being discussed over at your other haunt--as you well know
http://forum.nasaspaceflight.com/ind...topic=27446.30
http://forum.nasaspaceflight.com/ind...5960#msg835960

Two issues:
1) I don't post at that forum
2) it was the idea of the SLS being used for a moonlanding that I was calling sci-fi.

[NEOWatcher]

We are talking about landers. Why bring launch vehicles into the discussion?

[publiusr]

Actually I was talking about a crasher stage for a lander for a mission he called "sci-fi" Must have been ugordan I was thinking about. The HLLV bashers are hard to tell one from another in their penchant for dismissing sound engineering reasons behind HLLVs. You post links to trade publications and sound researchers who question the costs of EELV only methods, only to have them ignored.

Here is the SLS path to the moon (circumlunar)l at any rate:
http://www.nasaspaceflight.com/2012/...moon-outlined/

But of course the usual suspects whose credentials are nebulous at best think they are smarter than actual LV engineers and mission planners. That's the blogosphere for you.

My point was bringing up the use of the crasher stage to aid in landing, similar to the planned N1 mission, where the "RTB would act as a lunar crasher stage."

http://www.astronautix.com/engines/rd58.htm

Similar
http://forum.nasaspaceflight.com/ind...topic=27446.90

The Block D allows for smaller landers as we saw here: http://www.myspacemuseum.com/SOVPHOT1.HTM
Now, any proposed reusable lander will be bigger than this, but smaller than the original Altair. Its something to factor in--explaining why LV choice matters.

Icy moon landers
http://www.universetoday.com/93879/e...arch-for-life/

On the subject of landers, there is this
http://www.universetoday.com/93941/a...landing-spots/
So what challenges would be faced in lander design to deal with harsher locales? Inflatable landing pads on lander feet?

[Ara Pacis]

Scaling that up to a 1 g atmospheric earth-like environment doesn't work, nor would flying the entire vehicle, winged or not. It would be like landing the space shuttle in a remote area and trying to take off again. Given enough propellant, engines (rocket or air-breathing) it would be possible, just not efficient. In fact early shuttle proposals planned on self-ferry capability where they'd strap on jet engines and it would take off and fly back to the Cape. However it was costly, complex and inefficient so it wasn't pursued -- and that was on a developed planet where the additional fuel and engines could be delivered by truck.

There are other ways of creating a winged lander than the Space Shuttle Orbiter, which is a bad reference for multiple reasons. If a lander were to use hypersonic wave-rider principles or just be given a reduced speed for atmospheric interface, then a cumbersome TPS might not be needed. This less of the Space Shuttle and more like a Gulfstream V.

[DoggerDan]

There are other ways of creating a winged lander than the Space Shuttle Orbiter, which is a bad reference for multiple reasons.

Not the least of which is its size, designed to carry a crew of 7 and a payload of 53,600 lbs. If all you're talking about is a vehicle used for reentry and landing three people, a simple capsule works fine.

If a lander were to use hypersonic wave-rider principles or just be given a reduced speed for atmospheric interface, then a cumbersome TPS might not be needed. This less of the Space Shuttle and more like a Gulfstream V.

I'm thinking more of a lifting body shape for reentry, with F-111 - like wings for atmospheric maneuvering and low-velocity landing. Still, where would it land? A simple meadow would rip a Gulfstream's landing gear apart. If you're talking about a runway, no probleme.

[swampyankee]

Why didn't he simple say Earth? And how much material does he need to move from place to place once he lands? Parameters,Sir. Parameters.
The blimp is looking better and better ( but not in winter or icing conditions ) .

USN blimps have operated quite successfully in winter and icing conditions. See http://www.history.navy.mil/download/lta-10.pdf

[danscope]

Stll tricky, even dicey, but possible.

Best regards,
Dan

[Ara Pacis]

I'm thinking more of a lifting body shape for reentry, with F-111 - like wings for atmospheric maneuvering and low-velocity landing. Still, where would it land? A simple meadow would rip a Gulfstream's landing gear apart. If you're talking about a runway, no probleme.

Use a parachute, vectored thrust and skids.

[solitonmanny]

Greetings to all,

In reply to the first question in this thread started by Brown Motie, try to get a copy of Direct Mars by Prof. Zubrin, in this publication he lays out exactly what you are looking for.

Best wishes,

Manny
The Newbie

[danscope]

Your suggestion omits qualities in the OP. "Earth-like" has nothing to do with mars, which has so little atmosphere
( 1 / 200 th ) as to make moot that solution.