32 votes
Accepted

What's on the bottom of the Shuttle's external fuel tank?

It is an access hatch used during construction and maintenance. Credit: NASA-KSC Credit: NASA This part got at least some media coverage during the scrubbing of STS-121, when a Engine Cutoff (ECO) ...
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30 votes
Accepted

Challenger disaster: how full was the external tank at the time of destruction?

I did a crude spreadsheet sim using the Rogers Commission report to get throttle times, to wit: Throttle down to 94% at 24 seconds Throttle down to 65% at 42 seconds Throttle up to 104% at 65 seconds ...
29 votes
Accepted

What is the function of the corrugations on a section of the Space Shuttle's external tank?

That's the intertank - the cylinder that connected the bottom of the LO2 tank to the top of the LH2 tank. It didn't contain propellant, but did contain the forward interface with the Solid Rocket ...
26 votes

Challenger disaster: how full was the external tank at the time of destruction?

The breakup of Challenger occurred about 73 seconds into flight. Main engine cutoff normally occurs about 510 seconds into flight, implying that about 86% of the fuel would be remaining. (Many sources ...
23 votes

How was the space shuttle fuelled?

The shuttle external tank held the propellants for the shuttle main engines. It was filled from spherical tanks positioned at the perimeter of the launch pad. Insulated lines ran from the spheres, ...
22 votes

What's on the bottom of the Shuttle's external fuel tank?

This part of the External Tank is called the "LH2 Tank aft dome". There are really two large circular penetrations on it. They are the ones offset from the center of the tank. One is the access ...
18 votes
Accepted

Why is the Space Shuttle's External Tank fuelled through the Orbiter's main engine plumbing system?

I don't have a great reference for this, but it was to reduce cost on the throw-away External Tank. By using the same interface into the Orbiter used to supply propellants to the main engines, the ...
14 votes
Accepted

Why didn't the space shuttle use non-foam-shedding external tanks?

Setting aside the political/managerial issues this is about mass. The final version of the tank had a "dry" (empty tanks) mass of about 26.5 tons and a fuelled mass of about 760 tons. The surface area ...
14 votes
Accepted

Why is the shuttle's external tank's metal skin painted the same dark color as the foam insulation?

tl;dr - the parts at the rear of ET-94 where the foam was removed were painted orange for display. The foam was not dyed but started out a light cream color. It slowly turned orange when exposed to ...
10 votes
Accepted

What is the 'ET Disposal Problem'?

This was when planning safe disposal of the External Tank on certain types of launch abort. Source: Space Shuttle Abort Evolution page 9-10 A major design activity was conducted preparing for ...
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9 votes

What novel tank designs and ideas are out there to prevent fuel in a rocket tank from "sloshing around"?

Sloshing is not a problem in zero-g conditions. A key challenge with regard to starting the firing of a thruster in a zero-g situation is to get the propellant flowing to the thruster, without any ...
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9 votes

Why did the External Tank not have its own engines?

As a design decision, if you throw away the External Tank and it has engines attached, you are throwing away the engines. Since the Orbiter was returning for sure anyway, the decision was to leave ...
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9 votes
Accepted

How were the Space Shuttle and its External Tank connected (structurally)?

There were three attach points. The forward bipod that you show in your question, and two aft attach points. At each attach point a large bolt with an explosive nut held the tank and Orbiter together. ...
8 votes

Challenger disaster: how full was the external tank at the time of destruction?

A few facts: SRB Burn Time is 127 seconds Start of Challenger Incident- 64 s Vehicle breakup- 72 s Nominal time to orbit- 510 s. So the SRBs were about half-way done with their burn time before the ...
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7 votes

Why did the External Tank not have its own engines?

Reusability. The whole idea of the shuttle was to discard all the parts that are simple, cheap and easy to replace and recover everything expensive, complex and hard to replace. Of course the ...
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7 votes
Accepted

Why was the nose cone on the Space Shuttle's external tank pointy?

The original External Tank nose cone design was indeed blunt - almost like a fireplug, as seen in this 1975 concept art. [Image source - lost in the mists of time to me, but NASA somewhere] However, ...
5 votes
Accepted

Were there any cases of woodpeckers damaging Shuttle External Tank insulation other than that of STS-70?

STS-70 is the only case of woodpecker damage I know of. If you search the Space Shuttle Missions Summary document for "woodpecker", that is the only hit. Image Source Incidentally, they ...
5 votes
Accepted

What was the primary role of epoxy layer between metal structure and insulation foam on External Tank of Space Shuttle?

A Technical History of the Space Shuttle External Tank refers to the epoxy layer only as a "primer". The epoxy also had anti-corrosion properties. The document states BX 250, a foam which did not ...
5 votes
Accepted

Deciding factors for launch site

Safety distances are decided by modelling the worst-case scenario (an explosion of the rocket right on the launch pad). An explosion results in an overpressure which drops off as distance increases, ...
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4 votes
Accepted

Would the Space Shuttle External Tank have made orbit as a VT SSTO with 6 SSMEs?

What the equations I used completely ignore is initial thrust to gross launch mass which'd surely affect gravity drag? ... What is the assumption behind the 9.7 km/s delta-v on the Wikipedia page as ...
4 votes
Accepted

Why didn’t the space shuttle external tank have pressure-relief vents?

Your question is based on a misunderstanding- the External Tank propellant tanks did in fact have relief valves. The 02 valve relieved at 24 psid and the H2 valve relieved at 36 psid. From the 1982 ...
3 votes

What novel tank designs and ideas are out there to prevent fuel in a rocket tank from "sloshing around"?

Ways to do propellant tanks, with a view on preventing the propellant from "sloshing about". This sloshing could be either actual sloshing of liquid under gravity/acceleration in a tank, or ...
3 votes
Accepted

Would it be achievable to use the first stage of a launch to Venus as the envelope of an airship in its atmosphere?

Launch vehicles don't stage to get the earlier stages out of the way, they stage to get rid of excess mass so they can actually reach orbit with a useful payload. The Shuttle ET was a bit of an ...
2 votes

What is the 'ET Disposal Problem'?

I believe you are right, it is the External Tank. Why does it have problems? The external tanks were deposited in either the Indian or Pacific Oceans, clear across the world. So, what would that do ...
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1 vote

What were the Top 10 Shuttle Risks in John Young's "famous letter"?

I managed to find a news article that addresses some of this. Booster rocket seal conditions ... Challenger flight that exploded and killed its crew of seven, Young said, ″There is only one driving ...
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