Thomas Frieling in Spaceflight

On Sat, 09 Aug 2003 21:12:38 GMT, "gmw" wrote:

..... I have also
seen drawing and notes for a controlled landing by an advance Gemini capsule
using a fabric based, hang glider like Rollo wing. Putting the two together
and a reusable capsule is a very doable and much less expensive than many
make it out to be.

Tom's article proposes that a revived CM would make a land landing
somewhere in the US southwest, cushioned by either retro rockets or
air bags. That should take care of the salt water problem!

On Sat, 09 Aug 2003 18:54:25 GMT, Brian Thorn
wrote:

I think it would probably make more sense to go the wings or lifting
body route if reusability were your prime concern. Then you'd have the
SM functions in the same airframe and can reuse the whole shebang.


True. The point is if TPTB decide in the end to go for a capsule,
could it be resuable?

Brian Thorn writes:
Instead, it will have to have a honkin' big parachute/airfoil which
had better deploy just right. Even then, you might still need a retro
rocket to make landing bearable for the crew.

And how big a capsule can they fit on top of a Delta or Atlas before
they start getting into aerodynamic problems that make wings look
easy?

Capsules are still easier to launch on ELVs than anything with wings.
Their axisymmetric shape makes the aerodynamics much easier, even if
you have to resort to a "hammer head" design.

Every model rocket designer knows that you don't want to add large
aerodynamic surfaces at the nose of a rocket. I wonder why "real"
aerospace engineers often gloss over this issue when they propose
mounting anything with wings on an ELV. It really is a complex issue
that shouldn't be glossed over, yet how many "pretty pictures" have we
seen of an X-38 style CRV on top of a Delta IV or an Atlas V?

Still, Delta IV looks to be 5m diameter, which is larger than the
Apollo CSM's 3.90m diameter, and this is before you start talking
about "hammer head" shapes. Atlas V has a mild "hammer head" payload
fairing in order to achieve the same 5m diameter payload fairing. In
traditional US units, this is about 16.4 ft in diameter. That's a
pretty large capsule. I'll bet you could fit quite a few standard ISS
payload racks in a capsule this size.

Jeff
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Brian Thorn wrote:
(George William Herbert) wrote:
And keep in mind... a capsule is going to be lighter for the same
capabilities, as it doesn't have all those dead weight wings etc.

Instead, it will have to have a honkin' big parachute/airfoil which
had better deploy just right. Even then, you might still need a retro
rocket to make landing bearable for the crew.

Retro rocket, or moderate crush space in the seat mounts, etc.

And how big a capsule can they fit on top of a Delta or Atlas before
they start getting into aerodynamic problems that make wings look
easy?

Both Atlas V and Delta IV are qualifying with 5m shrouds.
So at least that big. There has been open speculation of
a 7m shroud to fit a winged OSP under while avoiding the
wing lift loads problem, so someone is thinking of that
sized hammerhead on both vehicles. A large hammerhead is
more drag, and more shroud weight, but is not an unmanageable
problem by any means.

A 5m capsule is plenty big for the OSP mission...


-george william herbert

On 11 Aug 2003 16:16:33 -0400, jeff findley
wrote:


Still, Delta IV looks to be 5m diameter, which is larger than the
Apollo CSM's 3.90m diameter, and this is before you start talking
about "hammer head" shapes. Atlas V has a mild "hammer head" payload
fairing in order to achieve the same 5m diameter payload fairing. In
traditional US units, this is about 16.4 ft in diameter. That's a
pretty large capsule. I'll bet you could fit quite a few standard ISS
payload racks in a capsule this size.

But not the payload racks and the Service Module.

Brian

Brian Thorn wrote:
wrote:
Still, Delta IV looks to be 5m diameter, which is larger than the
Apollo CSM's 3.90m diameter, and this is before you start talking
about "hammer head" shapes. Atlas V has a mild "hammer head" payload
fairing in order to achieve the same 5m diameter payload fairing. In
traditional US units, this is about 16.4 ft in diameter. That's a
pretty large capsule. I'll bet you could fit quite a few standard ISS
payload racks in a capsule this size.

But not the payload racks and the Service Module.

What service module are you referring to here?


-george william herbert

Brian Thorn wrote:
(George William Herbert) wrote:
I'll bet you could fit quite a few standard ISS
payload racks in a capsule this size.

But not the payload racks and the Service Module.

What service module are you referring to here?

The propulsion and power systems to get the racks to and from the
Space Station. Even if this requires only half the mass of the Apollo
SM (and I think that's a realistic ballpark figure), we're still
talking two or three times the mass of the CM alone. All in a capsule
only a couple of feet greater in diameter than Apollo.

Several feet greater in diameter, but I digress.

I recommend to you a bit of directed research:
go through the manned capsules section of Mark Wade's
site looking at the delta-V of space station logistics
vehicles real and proposed, and figure out their mass
ratios and fuel fractions. The best bets are to look
at the numbers for the various Soyuz models and the
British Aerospace Multi-Role Capsule.

"2-3 times the mass of the CM alone" is a gross, gross
overestimate. Small multiplier. Really.

I have no objection to a large capsule used for crew and cargo
transport. It's the proposal that the crew (or cargo) AND the service
systems (propulsion, life support -- more than a few hours worth --
and electrical power) can be all compressed into a 15-ft diameter
capsule that I have difficulty accepting. My argument is that if we
want to reuse the service systems in addition to the crew cabin, then
the capsule is less suited for it than a winged or lifting-body shape.

Look at all the MRC was able to compress into a single 4 meter capsule.

Work out the numbers on required delta-V, mass ratio, etc.

Design a few capsules, on a notepad. Just sketch them
to get an idea of volumetric requirements for people,
systems, fuel tanks, etc.

You can do a lot in 5 meters (16.4 feet).
Plenty, if your mission is OSP. Even the "7-8 passengers up
and down and/or lotsa racks" jumbo version.


-george william herbert

Brian Thorn writes:

The propulsion and power systems to get the racks to and from the
Space Station. Even if this requires only half the mass of the Apollo
SM (and I think that's a realistic ballpark figure), we're still
talking two or three times the mass of the CM alone. All in a capsule
only a couple of feet greater in diameter than Apollo.

You're being grossly mislead by a system designed for lunar travel.
The Apollo SM was grossly oversized for LEO missions. As such, you're
comparing apples and oranges. For reasonable sized service modules, I
suggest you look at vehicles (existing and proposed) that serve this
role in LEO.

I'd look at the delta-V of Progress, Soyuz, ATV, HTV, and the like.
You'll be pleasantly surprised that these don't require nearly the
delta-V needed to brake (the CSM and LM) into lunar orbit and later
put the CSM on an earth return trajectory.

I have no objection to a large capsule used for crew and cargo
transport. It's the proposal that the crew (or cargo) AND the
service systems (propulsion, life support -- more than a few hours
worth -- and electrical power) can be all compressed into a 15-ft
diameter capsule that I have difficulty accepting. My argument is
that if we want to reuse the service systems in addition to the crew
cabin, then the capsule is less suited for it than a winged or
lifting-body shape.

Where did you get 15 feet? You've got a 16.4 foot diameter limit, if
you're talking about using Delta IV or Atlas V as your launch vehicle.
That extra 1.4 feet buys you quite a bit of extra volume, since it
also lets the capsule be longer and still maintain an Apollo CM shape.

If you grossly simplify the problem as a cube, you see:

16.4ft ^ 3 = 4411ft^3
15ft ^ 3 = 3375ft^3

So that extra 1.4 feet of length increases your volume by nearly 1/3
of the smaller volume. I'll bet your LEO specified replacement SM
equipment will fit in that space.

Whether we should try to reuse the service systems is another matter.
But I think if we're going to aim for eventual reusability of the
command module, we should instead aim from the beginning for complete
reusability... command and service module... with an airframe designed
for it from the start.

No doubt. However, the devil in the details isn't as bad as you
suspect. We're trying to reuse the shape of the Apollo CM, the SM is
largely irrelevant. The systems the SM contains ought to be replaced
with more modern systems anyway. Especially the propulsion system,
where I'd want to get away from toxic propellants and switch to
something a bit more benign.

Jeff
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On 12 Aug 2003 11:17:40 -0400, jeff findley
wrote:

The propulsion and power systems to get the racks to and from the
Space Station. Even if this requires only half the mass of the Apollo
SM (and I think that's a realistic ballpark figure), we're still
talking two or three times the mass of the CM alone. All in a capsule
only a couple of feet greater in diameter than Apollo.

You're being grossly mislead by a system designed for lunar travel.

No, I'm not. Apollo was not designed for lunar travel, it was designed
as NASA's all-purpose manned spacecraft to succeed Mercury. The moon
mission came later.

That said, I am grossly overestimating its mass. Empty, the SM weighed
about 20,000 lbs., far less than I had thought. And that's about twice
as much as is needed for the LEO mission.

Remember that one of OSP's requirements is for greater maneuverability
than Shuttle. That's going to drive prop requirements significantly
higher.

I have no objection to a large capsule used for crew and cargo
transport. It's the proposal that the crew (or cargo) AND the
service systems (propulsion, life support -- more than a few hours
worth -- and electrical power) can be all compressed into a 15-ft
diameter capsule that I have difficulty accepting. My argument is
that if we want to reuse the service systems in addition to the crew
cabin, then the capsule is less suited for it than a winged or
lifting-body shape.

Where did you get 15 feet?

Lifeboat mode, to be launched aboard Shuttle. Unless we decide on two
variants (driving up costs) were stuck with 15 feet max.

Brian

Brian Thorn wrote:

On 12 Aug 2003 11:17:40 -0400, jeff findley
wrote:

The propulsion and power systems to get the racks to and from the
Space Station. Even if this requires only half the mass of the Apollo
SM (and I think that's a realistic ballpark figure), we're still
talking two or three times the mass of the CM alone. All in a capsule
only a couple of feet greater in diameter than Apollo.

You're being grossly mislead by a system designed for lunar travel.

No, I'm not. Apollo was not designed for lunar travel, it was designed
as NASA's all-purpose manned spacecraft to succeed Mercury. The moon
mission came later.

Yes you are. Apollo was *intended* as a general purpose orbiter, but
it's design was hardly begun before it's mission, and design, were
shifted to being the command craft for the lunar mission.

D.
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