SSU Development Thread (2.0 to 3.0)

[DaveS]

I have reservations about a forward TAA hatch, as there's always another hatch immediatly forward of it.

Checking my source again (Rockwell Intl STS Press Information, 1984) you're right, the TAA has only two pressure hatches, top and FWD. So revised it is this:

There's the middeck hatch (A), top airlock (B), aft airlock (C), top TAA (D), aft TAA (E), SpaceHAB (F).

For missions with the internal airlock the order is:
Middeck hatch (A), top TAA (B), aft TAA (C), SpaceHAB (D).

 

[Donamy]

Show me a picture of a spacehab hatch.

 

[DaveS]

Show me a picture of a spacehab hatch.

I remember reading about it somewhere, I just can't remember where.

 

[Donamy]

I don't believe the TAA had any hatches for STS-88, or the Mir missions, because they were'nt needed, only a spacer.

---------- Post added at 07:18 PM ---------- Previous post was at 07:16 PM ----------

STS-57 the TAA had 2 hatches, one on top and one before the spacehab.

 

[Urwumpe]

I don't believe the TAA had any hatches for STS-88, or the Mir missions, because they were'nt needed, only a spacer.

departmentalization is as important for spacecraft as for ships.

We do know that the external airlock has no hatch of its own forward, because the mid deck hatch does that function - but it had one aft.

 

[Donamy]

Yes, but would it, if the TAA was used aft of the airlock, such as STS-118, it wouldn't be needed for EVA, since the TAA has one. I mean, weight was at a premium for shuttle flights.

I don't know either, but it just seems logical to me.

 

[DaveS]

Yes, but would it, if the TAA was used aft of the airlock, such as STS-118, it wouldn't be needed for EVA, since the TAA has one. I mean, weight was at a premium for shuttle flights.

I don't know either, but it just seems logical to me.

You forget that the EVA hatch is the aft hatch of the airlock which is blocked by the tunnel leading to SpaceHAB. A suited EV do not fit through the ODS vestibule which has only a diameter of 0.8 m. An shuttle-based EVA is based not out of the airlock but the TAA. The ingress/egress point would have been through the TAA top hatch.

 

[Donamy]

That's what I said.

 

[Urwumpe]

Yes, but would it, if the TAA was used aft of the airlock, such as STS-118, it wouldn't be needed for EVA, since the TAA has one. I mean, weight was at a premium for shuttle flights.

I don't know either, but it just seems logical to me.

Weight yes. Costs as well. :lol:

The hatch wouldn't be needed, if you ignore the need for emergency EVAs, but building a TAA without hatch would have been more expensive than the weight penalty. Also the TAA was only needed to maintain a good CG position for re-entry.

 

[GLS]

Yes, but would it, if the TAA was used aft of the airlock, such as STS-118, it wouldn't be needed for EVA, since the TAA has one. I mean, weight was at a premium for shuttle flights.

I don't know either, but it just seems logical to me.

Another "I don't know" here, but I see a point for having a aft TAA hatch, so when going EVA from it, they wouldn't have to spend air to repressurize the tunnel, regardless of whether there's a hatch at SpaceHab/SpaceLab.

---------- Post added at 09:11 PM ---------- Previous post was at 09:08 PM ----------

Also the TAA was only needed to maintain a good CG position for re-entry.

And to provide an exit/entry for EVA on the flights where the airlock hatch was not available because of the tunnel.

 

[DaveS]

Another "I don't know" here, but I see a point for having a aft TAA hatch, so when going EVA from it, they wouldn't have to spend air to repressurize the tunnel, regardless of whether there's a hatch at SpaceHab/SpaceLab.

---------- Post added at 09:11 PM ---------- Previous post was at 09:08 PM ----------



And to provide an exit/entry for EVA on the flights where the airlock hatch was not available because of the tunnel.

Exactly. That was the sole reason for the TAA, to provide contingency EVA capability on missions where the normal EVA path was blocked.

This is from STS-106:

 

[Donamy]

Found this from STS-57 shows the airlock from the mid-deck. You can clearly see that there is no hatch between the airlock and TAA. It would be sitting on the floor.

 

[GLS]

Change of subject: can anyone confirm that the ODS attach (not docking) is/was working?

 

[Donamy]

Here is the TAA for STS-97, showing no hatches.

 

[Donamy]

Change of subject: can anyone confirm that the ODS attach (not docking) is/was working?

I can't get it to extend, but I may not be doing it correctly.

 

[DaveS]

I can't get it to extend, but I may not be doing it correctly.

The ODS operation procedures can be found in the Rendezvous checklist. The actual extension procedure can be found on page 8-8.

 

[Urwumpe]

Like this?

 

[Donamy]

Now that I think about it. That STS-57 was an internal airlock, so I don't know about the external airlock.

 

[Urwumpe]

Change of subject: can anyone confirm that the ODS attach (not docking) is/was working?

Not working right now, because the distance at which Orbiter automatically snaps the spacecraft together, is closer than the 45 cm to which the ring can be extended.

 

[DaveS]

Now that I think about it. That STS-57 was an internal airlock, so I don't know about the external airlock.

It's the same, except for the top hatch on the External Airlock.