Challenger

book

The book, “Challenger A Major Malfuntion” is a good insight to the whole
shuttle project, all the mistakes and bad practices are covered.
The programme was good tv though.

Of course! On the grounds it takes four (or six) times longer to burn through them

Horrible

Richard

Those O rings. I looked at those and thought fitting the second O ring looked like a frightful bodge. If the installation conditions meant that the first one fails, why would the second one be any better?

I think the problem was eventually ‘solved’ by fitting four (or six) o-rings! 😉

Well, I expect the cause of the disaster was a mystery to many but the Booster engineers that wouldn’t initially agree to the launch because of the known problems with the o-rings at low temperatures probably knew about ten seconds after it happened. Of course after the disaster it would be extremely embarrassing for NASA if the known problems with the o-rings were shown to be the cause; was the cause really that much of a mystery or, as you say, was the cause just ‘hidden’ until the enquiry (re)discovered it?

I haven’t read Richard Feynman’s book but it was nice to see a TV programme made on the subject (although I found its portrayal of engineers the usual two-dimensional caricatures that popular media always portrays).

CD – it was of course a complete mystery as to the cause, prior to the enquiry and the outcome of the enquiry left no one in any doubt, as was made clear in the programme, if you saw it, but in even more detail in Feyman’s book, as you will know if you have read it. The exposure of the attempts to “hide” the truth was revelatory.

Those O rings. I looked at those and thought fitting the second O ring looked like a frightful bodge. If the installation conditions meant that the first one fails, why would the second one be any better?

Richard

I forgot to mention if you want to see it again or missed it, its on the BBC iplayer website.

Not sure if this is the right forum, but did anyone see this dramatised reconstruction of the enquiry into the Challenger disaster on BBC2 last night, with William Hurt as Feynman? .

Very good programme !

I don’t think there is any doubt that the cause of the disaster was the seals in the solid-fuel Boosters; the Boosters survived the explosion, kept burning, and were recovered more-or-less intact afterwards. The physical blow-by evidence was seen on the Boosters and was judged to have not been the result of damage sustained during the explosion. And as you say, video footage showed the blow-by before the explosion too.

The Boosters were a reusable item anyway; being routinely recovered from the sea and refurbished. The o-ring seals were always replaced and when seals from previous launches were examined there was evidence of some blow-by leakage. This was a known issue but was acceptable within certain parameters.

I don’t think there was any real mystery in the cause of the disaster, the Booster engineers objected to the launch in the hours before the disaster; the only ‘mystery’ was why they were overruled and how those that overruled then tried to explain their actions.

Why on earth have they got it so wrong????, main engine tests resulting in cracked turbine blades?????

The Challenger main engines never had any blades!!!!!!

John.

Me too! I thought that.

They spoke of the sections of the solid rocket booster “O” Rings. If you study the video of the launch carefully you can see the flame between the Shuttle and connection to the main booster.

Also I understand the whole thing is assembled in the VAB. So the “o” ring would not have been exposed to freezing temperatures, and would have compressed and formed itself to make a seal. Cant see how it can change shape afterwards. Though the findings seem to be blaming the cold at the launch site on the day of the launch making the Rubber “O” Ring seals brittle.

Still a tragic accident.

It just seemed curious to me that a (possibly) rubber product could be used to seal what I suppose are separate sections of a long rocket casing given the high combustion temperatures going on inside.

The seals for the solid-fuel Boosters are actually made with ‘wet’ clay I think; the ‘rubber’ o-ring seals are actually to prevent the clay from being squeezed out of the joint by the combustion pressures.

The irony is that the solid-fuel Boosters don’t need to be manufactured in sections at all; they are made that way to allow transportation from where they are made. I believe it was a political decision to spread the Shuttle work around the United States rather than to concentrate it in one state near the launch site.

As a matter of interest were the O rings in the booster solid rockets made from the same nitrile rubber as the ones you can buy at a plumbers shop only bigger.

I wondered about that, and I think it was the clamp he bought, not the rubber section

Richard

Why on earth have they got it so wrong????, main engine tests resulting in cracked turbine blades?????

The Challenger main engines never had any blades!!!!!!

John.

The SSME turbopumps have blades.

Late in 1977, two failures of HPFTP turbine blades
occurred just two weeks apart [25]. On November 17,
Test 902-095 on Engine 0002 was cutoff prematurely,
while operating at 70 percent power level, by the
HPOTP vibration redline monitor. The average
HPOTP vibration level had increased from 3 g rms to
over 70 g rms. However, it was subsequently discovered
that the vibration originated in the HPFTP which
violently shook the entire engine. The test was not
shut down by the HPFTP vibration monitor because it
had a built-in time delay of 0.240 seconds, and the
HPOTP redline time delay was only 0.100 seconds. A
post-test inspection revealed that a first-stage turbine
blade had broken off and inflicted significant damage
to both turbine stages.

http://www.enginehistory.org/SSME/SSME6.pdf

Excellent piece of television. As a matter of interest were the O rings in the booster solid rockets made from the same nitrile rubber as the ones you can buy at a plumbers shop only bigger. It just seemed curious to me that a (possibly) rubber product could be used to seal what I suppose are separate sections of a long rocket casing given the high combustion temperatures going on inside.

Why on earth have they got it so wrong????, main engine tests resulting in cracked turbine blades?????

The Challenger main engines never had any blades!!!!!!

John.

Why can’t the BBC give us more of the same standard? I thought it was first class,
Jim

A fascinating piece of TV, very informative and well worth watching.

I saw it too, excellent piece of telly.

Yes, saw it. Thought it was excellent.

This sort of stuff is what I pay my TV License for.