Really large airlocks

Some airlocks in lunar or O'Neill colonies will need to be huge, with
doors 10m or so across, to allow small ships, surface vehicles, large
cargo items to enter. I doubt these will look like the metal hatches
we're used to seeing. What possible designs are there?
I would suggest a flexible, kevlar-reinforced fabric door rolling down
like some current warehouse doors (which can close in seconds). The
edges would be riding in tracks/grooves and, once in closed position,
all four edges would be clamped and sealed. Reliability needs would
suggest more than one such door/membrane at each opening in case one
leaks or is ruptured. The greatest problem on Luna will probably be
the abrasive dust settling in the tracks.

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oups.com...
Some airlocks in lunar or O'Neill colonies will need to be huge, with
doors 10m or so across, to allow small ships, surface vehicles, large
cargo items to enter. I doubt these will look like the metal hatches
we're used to seeing.

Why not? What's wrong with that sort of design?

What possible designs are there?
I would suggest a flexible, kevlar-reinforced fabric door rolling down
like some current warehouse doors (which can close in seconds). The
edges would be riding in tracks/grooves and, once in closed position,
all four edges would be clamped and sealed. Reliability needs would
suggest more than one such door/membrane at each opening in case one
leaks or is ruptured. The greatest problem on Luna will probably be
the abrasive dust settling in the tracks.

The sealing mechanism here sounds more complex than a seal on an inwardly
opening conventional airlock door. The advantage of opening inward is that
the air pressure in the base puts a lot of pressure on the seal. Your
proposed design doesn't seem to do that, at least not that I can see.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

Jeff Findley wrote:
wrote in message
oups.com...
Some airlocks in lunar or O'Neill colonies will need to be huge, with
doors 10m or so across, to allow small ships, surface vehicles, large
cargo items to enter. I doubt these will look like the metal hatches
we're used to seeing.

Why not? What's wrong with that sort of design?

Assuming a 10m wide door, a conventional hatch would waste 10m of floor
space as it swings. It would be massive and relatively slow to
open/close. In an emergency speed may be important. Though I suppose
we could make a metal hatch that slides sideways.

What possible designs are there?
I would suggest a flexible, kevlar-reinforced fabric door rolling down
like some current warehouse doors (which can close in seconds). The
edges would be riding in tracks/grooves and, once in closed position,
all four edges would be clamped and sealed. Reliability needs would
suggest more than one such door/membrane at each opening in case one
leaks or is ruptured. The greatest problem on Luna will probably be
the abrasive dust settling in the tracks.

The sealing mechanism here sounds more complex than a seal on an inwardly
opening conventional airlock door. The advantage of opening inward is that
the air pressure in the base puts a lot of pressure on the seal. Your
proposed design doesn't seem to do that, at least not that I can see.

The bladders/seals riding on the edges of the membrane could be
designed to press into the track as the membrane becomes taut. Another
advantage is that a membrane door could be easier and faster to replace
if damaged.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

wrote in message
ps.com...

Jeff Findley wrote:
wrote in message
oups.com...
Some airlocks in lunar or O'Neill colonies will need to be huge, with
doors 10m or so across, to allow small ships, surface vehicles, large
cargo items to enter. I doubt these will look like the metal hatches
we're used to seeing.

Why not? What's wrong with that sort of design?

Assuming a 10m wide door, a conventional hatch would waste 10m of floor
space as it swings. It would be massive and relatively slow to
open/close. In an emergency speed may be important. Though I suppose
we could make a metal hatch that slides sideways.

Yes you could. Ever look at the mechanics of a sliding door on a van or
minivan? Same basic concept. You stick the door on tracks that pull the
door away from the seal, then curve them 90 degrees so the door slides to
the side once the seals are clear.

What possible designs are there?
I would suggest a flexible, kevlar-reinforced fabric door rolling down
like some current warehouse doors (which can close in seconds). The
edges would be riding in tracks/grooves and, once in closed position,
all four edges would be clamped and sealed. Reliability needs would
suggest more than one such door/membrane at each opening in case one
leaks or is ruptured. The greatest problem on Luna will probably be
the abrasive dust settling in the tracks.

The sealing mechanism here sounds more complex than a seal on an inwardly
opening conventional airlock door. The advantage of opening inward is
that
the air pressure in the base puts a lot of pressure on the seal. Your
proposed design doesn't seem to do that, at least not that I can see.

The bladders/seals riding on the edges of the membrane could be
designed to press into the track as the membrane becomes taut. Another
advantage is that a membrane door could be easier and faster to replace
if damaged.

I doubt a 10m wide door designed to hold sea level pressure would be damaged
very easily. What you have to worry about is damaging the seal (lunar
dust). I'd worry about comparing the ease of replacing the seal(s) on
either design. It seems to me a track based seal like you propose might end
up being more easily damaged by lunar dust since it would be harder to clean
before shutting the door. An inward opening hard door could have its seal
on the wall instead of the door, with the door itself only containing a
smooth metal surface to contact the seal.

I'm not saying your proposal would be a bad design, I'm just thinking it
would be a more complex, failure prone design in an area where you ought to
be using a robust, reliable design. In this case, I'd worry less about the
mass and bulk of the door and more about how reliable it's going to be over
hundreds or thousands of airlock cycles.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

"Jeff Findley" wrote in message
...

wrote in message
ps.com...

Jeff Findley wrote:
wrote in message
oups.com...
Some airlocks in lunar or O'Neill colonies will need to be huge, with
doors 10m or so across, to allow small ships, surface vehicles, large
cargo items to enter. I doubt these will look like the metal hatches
we're used to seeing.

Why not? What's wrong with that sort of design?

Assuming a 10m wide door, a conventional hatch would waste 10m of floor
space as it swings. It would be massive and relatively slow to
open/close. In an emergency speed may be important. Though I suppose
we could make a metal hatch that slides sideways.

Yes you could. Ever look at the mechanics of a sliding door on a van or
minivan? Same basic concept. You stick the door on tracks that pull the
door away from the seal, then curve them 90 degrees so the door slides to
the side once the seals are clear.

What possible designs are there?
I would suggest a flexible, kevlar-reinforced fabric door rolling down
like some current warehouse doors (which can close in seconds). The
edges would be riding in tracks/grooves and, once in closed position,
all four edges would be clamped and sealed. Reliability needs would
suggest more than one such door/membrane at each opening in case one
leaks or is ruptured. The greatest problem on Luna will probably be
the abrasive dust settling in the tracks.

The sealing mechanism here sounds more complex than a seal on an
inwardly
opening conventional airlock door. The advantage of opening inward is
that
the air pressure in the base puts a lot of pressure on the seal. Your
proposed design doesn't seem to do that, at least not that I can see.

The bladders/seals riding on the edges of the membrane could be
designed to press into the track as the membrane becomes taut. Another
advantage is that a membrane door could be easier and faster to replace
if damaged.

I doubt a 10m wide door designed to hold sea level pressure would be
damaged very easily. What you have to worry about is damaging the seal
(lunar dust). I'd worry about comparing the ease of replacing the seal(s)
on either design. It seems to me a track based seal like you propose
might end up being more easily damaged by lunar dust since it would be
harder to clean before shutting the door. An inward opening hard door
could have its seal on the wall instead of the door, with the door itself
only containing a smooth metal surface to contact the seal.

I'm not saying your proposal would be a bad design, I'm just thinking it
would be a more complex, failure prone design in an area where you ought
to be using a robust, reliable design. In this case, I'd worry less about
the mass and bulk of the door and more about how reliable it's going to be
over hundreds or thousands of airlock cycles.

I agree with you. A lunar colony would also need big doors for their
garages. A really big door could have a really big seal. If the rubber
seal is a foot wide all the way around, a few grains of sand won't do much
to it, so it may work dirty. Of course you would want to clean it
occasionally.