Author Topic: Shuttle Q&A Part 5  (Read 1542473 times)

Offline mjp25

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Re: Shuttle Q&A Part 5
« Reply #700 on: 10/06/2009 10:49 pm »
Why is the orbiter not placed on the Orbiter Transporter System when it is taken off of the mate/demate device at KSC? Was the MDD not designed to lower the orbiter with enough precision? Thanks.

Offline K466

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Re: Shuttle Q&A Part 5
« Reply #701 on: 10/06/2009 11:19 pm »
Why is the orbiter not placed on the Orbiter Transporter System when it is taken off of the mate/demate device at KSC? Was the MDD not designed to lower the orbiter with enough precision? Thanks.

The wheels have to be replaced anyway after a flight, it is faster to just tow it to the OPF.

Before they got the Orbiter Transporter System the orbiters were towed during rollover too.
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Offline mjp25

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Re: Shuttle Q&A Part 5
« Reply #702 on: 10/07/2009 12:09 am »
Thanks. That makes sense. The OTS was originally for the long tow at Vandenberg right?

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #703 on: 10/07/2009 12:47 am »
Why is the orbiter not placed on the Orbiter Transporter System when it is taken off of the mate/demate device at KSC? Was the MDD not designed to lower the orbiter with enough precision? Thanks.

The wheels have to be replaced anyway after a flight, it is faster to just tow it to the OPF.

Before they got the Orbiter Transporter System the orbiters were towed during rollover too.

Then why was it built in the first place.  The orbiters have wheels, why not just use them.  Just raise the gear after the orbiter gets onto the cranes in the VAB.

And, can't they get more than one landing out of a set of tires.  Do they actually go out of specs (thread thickness) in a single landing?  Why not throw on some more tread and get at least two landing before new tires are needed.

Danny Deger

Edit: OK I just read on another post the cart was built for a long tow at Vandenburg.  This almost makes sense, bearing temps or something might go out of specs for a long tow -- even then I don't see what is wrong with a long tow.  But why then move the darn thing to KSC and use it instead of just towing to the VAB for stacking.
« Last Edit: 10/07/2009 12:54 am by Danny Dot »
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Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #704 on: 10/07/2009 01:00 am »
Why is the orbiter not placed on the Orbiter Transporter System when it is taken off of the mate/demate device at KSC? Was the MDD not designed to lower the orbiter with enough precision? Thanks.

The wheels have to be replaced anyway after a flight, it is faster to just tow it to the OPF.

Before they got the Orbiter Transporter System the orbiters were towed during rollover too.

You meant to say tires didn't you.  The brakes were redesigned in about 1995 to allow for multiple uses.  The old brakes broke up with a single use and tended to stick and what not.  Really, really bad brakes.  You couldn't use them, let up, then use them again.  The pads would fracture at the first use and then when released, fractured pieces of brake pad would do nasty things to the brake assembly with the second application.  They were an accident ready to happen and NASA fixed them.  They also added the drag chute for crew safety at about this time.

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Offline Jim

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Re: Shuttle Q&A Part 5
« Reply #705 on: 10/07/2009 01:40 am »

Edit: OK I just read on another post the cart was built for a long tow at Vandenburg.  This almost makes sense, bearing temps or something might go out of specs for a long tow -- even then I don't see what is wrong with a long tow.  But why then move the darn thing to KSC and use it instead of just towing to the VAB for stacking.

The "tow" route was hilly. Also the OTS allows for the gear to be retracted in a better facility

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #706 on: 10/07/2009 01:58 am »

Edit: OK I just read on another post the cart was built for a long tow at Vandenburg.  This almost makes sense, bearing temps or something might go out of specs for a long tow -- even then I don't see what is wrong with a long tow.  But why then move the darn thing to KSC and use it instead of just towing to the VAB for stacking.

The "tow" route was hilly. Also the OTS allows for the gear to be retracted in a better facility

I can certainly see the need for a cart on hilly terrain.  Towing on a hill is a big time no-no.  Way too much stress on the nose gear and tow bar.  Enough to maybe snap the nose gear off.

If I recall the gear goes up very nicely in the VAB.  Don't they pretty much raise them selves with pneumatic actuators in the orbiter wheel wells.  The final raising is a ceremony where a $8 push broom is used to close the nose gear doors. 

Danny Deger

Edit: Why was there a need to tow on hilly terrain at Vandie?  Sounds like a really bad place for shuttle OPS is there was not enough room to avoid hilly terrain.  Even then, we have machines called "earth moving equipment" to level a road bed.   
« Last Edit: 10/07/2009 02:10 am by Danny Dot »
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Offline Jim

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Re: Shuttle Q&A Part 5
« Reply #707 on: 10/07/2009 11:24 am »

Edit: Why was there a need to tow on hilly terrain at Vandie?  Sounds like a really bad place for shuttle OPS is there was not enough room to avoid hilly terrain.  Even then, we have machines called "earth moving equipment" to level a road bed.   

You haven't been to VAFB.  Launch pads were in canyons.  The tow route was more than 5 (maybe twenty) miles.  The OMCF was on the north base and SLC-6 was on the south base.

Offline tva

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Re: Shuttle Q&A Part 5
« Reply #708 on: 10/07/2009 12:01 pm »
You haven't been to VAFB.  Launch pads were in canyons.  The tow route was more than 5 (maybe twenty) miles.  The OMCF was on the north base and SLC-6 was on the south base.
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Offline Jim

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Re: Shuttle Q&A Part 5
« Reply #709 on: 10/07/2009 12:17 pm »
That isn't the exact route.

I will try to find it

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #710 on: 10/07/2009 12:36 pm »

Edit: Why was there a need to tow on hilly terrain at Vandie?  Sounds like a really bad place for shuttle OPS is there was not enough room to avoid hilly terrain.  Even then, we have machines called "earth moving equipment" to level a road bed.   

You haven't been to VAFB.  Launch pads were in canyons.  The tow route was more than 5 (maybe twenty) miles.  The OMCF was on the north base and SLC-6 was on the south base.

Sounds like a place to NOT do shuttle ops.  Why in the heck did DOD buy off on this vs. Titans, etc.  NASA should not have gotten in the business of doing 100 precent of DOD and comercial launches with an unproven design.   Heck, the brakes distroyed themselves during each landing.  Hardly a design for quick turn around.  Look at how long it takes to hook the shuttle up to the launch tower.  No way for a quick turn around. 

Enough said for the Q&A thread.  Please don't reply to this here. 

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Offline K466

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Re: Shuttle Q&A Part 5
« Reply #711 on: 10/07/2009 06:50 pm »
Why is the orbiter not placed on the Orbiter Transporter System when it is taken off of the mate/demate device at KSC? Was the MDD not designed to lower the orbiter with enough precision? Thanks.

The wheels have to be replaced anyway after a flight, it is faster to just tow it to the OPF.

Before they got the Orbiter Transporter System the orbiters were towed during rollover too.

You meant to say tires didn't you.  The brakes were redesigned in about 1995 to allow for multiple uses.  The old brakes broke up with a single use and tended to stick and what not.  Really, really bad brakes.  You couldn't use them, let up, then use them again.  The pads would fracture at the first use and then when released, fractured pieces of brake pad would do nasty things to the brake assembly with the second application.  They were an accident ready to happen and NASA fixed them.  They also added the drag chute for crew safety at about this time.

Danny Deger

Yes I meant to say tires.

The rear tires, as I understand, can only be used once, due to the high landing speeds. The front tires can be used for two landings.
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Offline Antares

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Re: Shuttle Q&A Part 5
« Reply #712 on: 10/07/2009 08:00 pm »
With the SSME having LO2 and LH as fuel, when the engines are first started, is it with the Liquid or gaseous O2 and H.  I was just wondering how it is vaporized before the engines are started or is it liquid when it ignites and during the flight?

Cryo engines have liquid down to the last wet closed valve prior to start.  When the valves start opening, all of the hardware has to quench to liquid or near liquid temperatures.  So initially there's some "hot" vapor coming out of the injectors as heat comes out of the hardware and into the propellants.  Since combustion stability is really sensitive to the thermodynamic conditions of the propellant and local mixture ratios, this is why the start sequence valve positions are often really odd.  Eventually the injectors prime and the propellant is liquid or at least supercritical up to the cold side of injector.  Almost always, propellant comes out of the injector as gas since only gases can burn.  The pressure loss across the injector vaporizes the propellant.
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Offline brettreds2k

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Re: Shuttle Q&A Part 5
« Reply #713 on: 10/08/2009 06:34 pm »
Why does it take 1 week normally from the time the shuttle is connected to the Tank and Boosters in the VAB to roll it out? Once connected what tasks do they go through? Are there many, or just a few but are time consuming?

Also I know the fuel from the tank goes through lines at the base of the tank into the shuttle via connections to both, But does anyone have a diagram that shows how they join together? And when the tank seperates on orbit does the doors seal the same as landing gear doors (Do they come down) or do they slide over to cover the connection point? What if it failed to close?
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Offline Jorge

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Re: Shuttle Q&A Part 5
« Reply #714 on: 10/08/2009 07:01 pm »

And when the tank seperates on orbit does the doors seal the same as landing gear doors (Do they come down) or do they slide over to cover the connection point?

The doors are hinged on the inboard side, and after ET sep they flip 180 degrees to close.

http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/sep/umbdoors.html

Photo here:

http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=43554

Quote
What if it failed to close?

The doors can be closed manually via EVA. The area around the doors is (just barely) reachable by an astronaut in a foot restraint on the tip of the OBSS at the end of the RMS.

If the doors can't be closed at all, LOV/C.
« Last Edit: 10/08/2009 07:19 pm by Jorge »
JRF

Offline Jim

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Re: Shuttle Q&A Part 5
« Reply #715 on: 10/08/2009 07:16 pm »
Why does it take 1 week normally from the time the shuttle is connected to the Tank and Boosters in the VAB to roll it out? Once connected what tasks do they go through? Are there many, or just a few but are time consuming?


Not only do they have to mechanically mate the orbiter to the ET but also electrical and fluid connections. Additionally, the umbilicals to the TSM's have to be mated.  The fluid connections have to be leak check and interface tests have to be done to verify all the electrical connections between the MLP and the vehicle and between the orbiter and ET.
« Last Edit: 10/08/2009 07:17 pm by Jim »

Offline brettreds2k

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Re: Shuttle Q&A Part 5
« Reply #716 on: 10/08/2009 07:21 pm »

And when the tank seperates on orbit does the doors seal the same as landing gear doors (Do they come down) or do they slide over to cover the connection point?

The doors are hinged on the inboard side, and after ET sep they flip 180 degrees to close.

http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/sep/umbdoors.html

Photo here:

http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=43554

Quote
What if it failed to close?

The doors can be closed manually via EVA. The area around the doors is (just barely) reachable by an astronaut in a foot restraint on the tip of the OBSS at the end of the RMS.

If the doors can't be closed at all, LOV/C.

Thank you so much for the picture of the doors, Not something I have ever seen. Thanks so much!!
Brett
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[ ] Enterprise
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Offline Alpha Control

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Re: Shuttle Q&A Part 5
« Reply #717 on: 10/08/2009 11:59 pm »

And when the tank seperates on orbit does the doors seal the same as landing gear doors (Do they come down) or do they slide over to cover the connection point?

The doors are hinged on the inboard side, and after ET sep they flip 180 degrees to close.

http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/sep/umbdoors.html

Photo here:

http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=43554

Quote
What if it failed to close?

The doors can be closed manually via EVA. The area around the doors is (just barely) reachable by an astronaut in a foot restraint on the tip of the OBSS at the end of the RMS.

If the doors can't be closed at all, LOV/C.

Jorge; two follow-ups, if I may:

(1) Regarding the manual closure of the ET umbilical doors, how is this done? Via a hand crank of some kind?

(2) Prior to the OBSS era, how would the EVA crewmember accomplish this without the extra reach provided by the boom? Thanks.
« Last Edit: 10/08/2009 11:59 pm by Alpha Control »
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Offline Jorge

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Re: Shuttle Q&A Part 5
« Reply #718 on: 10/09/2009 01:28 am »

And when the tank seperates on orbit does the doors seal the same as landing gear doors (Do they come down) or do they slide over to cover the connection point?

The doors are hinged on the inboard side, and after ET sep they flip 180 degrees to close.

http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/sep/umbdoors.html

Photo here:

http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=43554

Quote
What if it failed to close?

The doors can be closed manually via EVA. The area around the doors is (just barely) reachable by an astronaut in a foot restraint on the tip of the OBSS at the end of the RMS.

If the doors can't be closed at all, LOV/C.

Jorge; two follow-ups, if I may:

(1) Regarding the manual closure of the ET umbilical doors, how is this done? Via a hand crank of some kind?

There is no crank. What the crew would do depends on the failure mode. If centerline latch, open the latch manually and allow the motors to close the doors. There are two motors on each door, geared such that a jam in one motor cannot prevent the other motor from closing the door. An EVA astronaut could probably not close the door manually with a dual motor failure, but two independent failures like that is highly unlikely.

Quote
(2) Prior to the OBSS era, how would the EVA crewmember accomplish this without the extra reach provided by the boom? Thanks.

Prior to the EVA, the crew would improvise a bolo using a bag full of clothes and an EVA safety tether. The EVA crewmember would translate to the aft end of the payload bay along the EVA slidewire on the sill, secure the tether end of the bolo to the slidewire, then sling the bolo such that the bag catches in the gap between the inboard elevon and the aft fuselage (this would likely take several attempts). The EVA cremember would then attach his own safety tether to the bolo, translate down the bolo to the elevon, then pull himself over the side. The umbilical doors are reachable from the underside of the elevon.

This EVA was considered unlikely to work and consequently not taken seriously by most astronauts.

Nevertheless, there was (and maybe still is) a high-fidelity mockup of the ET umbilical doors in the highbay of JSC building 9 for EVA training.
« Last Edit: 10/09/2009 01:33 am by Jorge »
JRF

Offline Alpha Control

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Re: Shuttle Q&A Part 5
« Reply #719 on: 10/09/2009 02:55 am »

And when the tank seperates on orbit does the doors seal the same as landing gear doors (Do they come down) or do they slide over to cover the connection point?

The doors are hinged on the inboard side, and after ET sep they flip 180 degrees to close.

http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/sep/umbdoors.html

Photo here:

http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=43554

Quote
What if it failed to close?

The doors can be closed manually via EVA. The area around the doors is (just barely) reachable by an astronaut in a foot restraint on the tip of the OBSS at the end of the RMS.

If the doors can't be closed at all, LOV/C.

Jorge; two follow-ups, if I may:

(1) Regarding the manual closure of the ET umbilical doors, how is this done? Via a hand crank of some kind?

There is no crank. What the crew would do depends on the failure mode. If centerline latch, open the latch manually and allow the motors to close the doors. There are two motors on each door, geared such that a jam in one motor cannot prevent the other motor from closing the door. An EVA astronaut could probably not close the door manually with a dual motor failure, but two independent failures like that is highly unlikely.

Quote
(2) Prior to the OBSS era, how would the EVA crewmember accomplish this without the extra reach provided by the boom? Thanks.

Prior to the EVA, the crew would improvise a bolo using a bag full of clothes and an EVA safety tether. The EVA crewmember would translate to the aft end of the payload bay along the EVA slidewire on the sill, secure the tether end of the bolo to the slidewire, then sling the bolo such that the bag catches in the gap between the inboard elevon and the aft fuselage (this would likely take several attempts). The EVA cremember would then attach his own safety tether to the bolo, translate down the bolo to the elevon, then pull himself over the side. The umbilical doors are reachable from the underside of the elevon.

This EVA was considered unlikely to work and consequently not taken seriously by most astronauts.

Nevertheless, there was (and maybe still is) a high-fidelity mockup of the ET umbilical doors in the highbay of JSC building 9 for EVA training.

Fascinating. Thanks very much for the detailed info.
« Last Edit: 10/09/2009 03:38 am by Alpha Control »
Space launches attended:
Antares/Cygnus ORB-D1 Wallops Island, VA Sept 2013 | STS-123 KSC, FL March 2008 | SpaceShipOne Mojave, CA June 2004

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