Space Shuttle RTLS article

[bitchstewie]

Oldish and I'm sure there are loads out there but I felt it was worth sharing

http://www.tested.com/science/space/460233-space-s...

[Eric Mc]

Might be worth posting in the "Science" forum where most of us space cadets hang out.

The RTLS (Return to Launch site) abort was something nobody really thought was feasible.

The Shuttle was pretty much a craft that had top work pretty much 100% If it didn't, you were dead.

[Simpo Two]

If they'd put that much effort into making it work, they wouldn't have needed to invent 27 different ways for it not to work.

[Eric Mc]

Don't quite get what you're trying to say.

One alternative that John Young tried to push was, rather than try to get the Shuttle back to the runway at Kennedy, he thought a more feasible approach would be to have it turn to the north and try to land it on one of the many fairly long runways available at some east coast military air bases and civil airports.

He ran a few simulations on this and it seemed to have a higher success rate than the RTLS abort.

However, NASA never adopted Young's idea - something he was pretty miffed about.

[Simpo Two]

Eric Mc said:

Don't quite get what you're trying to say.

Starting with a maximum possible technical effort of 100%, put 100% of it into a system that will work, rather than 60% into the system that is supposed to work and 40% into systems to help if it doesn't. Assuming that those systems don't fail as well of course, because almost nothing related to space seems to work properly now.

[Eric Mc]

I think you are way too pessimistic. Launching rockets and controlling spacecraft has always been a tricky business. On the whole, most space technology works most of the time. When dealing with manned spacecraft - especially during the launch phase - abort options MUST be engineered into the system and rehearsed by those who might have to use them. The Shuttle was a particularly risky system with very limited and probably unsurvivable abort options in a lot of scenarios.

That is why NASA has abandoned any further Shuttle-type configurations for any future manned projects. Indeed, even though we might see spaceplanes again at some point in the future, I don't ever see anybody coming up with a piggyback launch configuration as used by the Space Shuttle. That was the single biggest reason why the abort options during a Shuttle launch were so limited.

[bitchstewie]

I've seen John Young on a few Discovery/National Geo type shows.

Always makes me laugh with how dry (not sure how else to put it) he seems to be.

Not sure you could have paid me to go up in that thing for the first flight.

[Dr Jekyll]

Slightly OT. But according to that article the external tank was jettisoned after main engine cut off. Surely at this point there is no power so the Shuttle + tank is going ballistic. So why should the jettisoned tank fall back to earth and the Shuttle continue into orbit?

[Eric Mc]

Dr Jekyll said:

Slightly OT. But according to that article the external tank was jettisoned after main engine cut off. Surely at this point there is no power so the Shuttle + tank is going ballistic. So why should the jettisoned tank fall back to earth and the Shuttle continue into orbit?

Well spotted.

When the Shuttle's Main Engines cut out and the tank was jettisoned, the Shuttle had not quite reached orbital velocity (17,500 mph approximately). This was deliberate as it ensured that the tank would not stay in orbit following the Orbiter around the earth and getting in the way of operations. The tank, of course, fell back into the atmosphere somewhere over the Indian Ocean and burned up. In order to achieve orbital velocity, the Orbiter fired its two Orbital Manoeuvering System (OMS) engines for a couple of minutes which gave it the added oomph (technical term) to reach the desired orbit.

The OMS engines operated from their own set of fuel tanks.They were hypergolic i.e. they used fuels that ignited on contact. The OMS rockets were used to adjust the height of the Shuttle's orbit and were also used to slow the Shuttle down prior to re-entering the atmosphere. The OMS were at the rear of the Orbiter and were attached to the back of the OMS pods.

[Simpo Two]

Eric Mc said:

I think you are way too pessimistic. Launching rockets and controlling spacecraft has always been a tricky business. On the whole, most space technology works most of the time. When dealing with manned spacecraft - especially during the launch phase - abort options MUST be engineered into the system and rehearsed by those who might have to use them. The Shuttle was a particularly risky system with very limited and probably unsurvivable abort options in a lot of scenarios.

I adopt a cynical approach so that if something does unexpectedly work I can feel surprised and happy.

I can't argue with one abort system, but think that four that conflict with each other depending on which way up you are and the day of the week is complexity guaranteed to cause failure. But we love 'tech', so keep cramming more and more in, not because it is needed, but because we can. (Whoops, touch of JFK there!)

[Eric Mc]

The designers of the Shuttle did not design it as a complex machine because they wanted to make it complex. If you read the history of the politics and decision making behind how it came to be what it was, you will realise that they tried desperately to make it as practical and basic as they could - but there were too many factors pushing it down certain paths which resulted in what they ended up with.

Trying to make an all singing, all dancing machine that satisfied all the requirements being asked of it proved too much for the technology of the mid 1970s.

[Boatbuoy]

Saying you want to spend 100% of your development budget costs/time on developing something so that it wont fail is ridiculous. Lets apply that to something a bit more relevant, like Airliners. We could engineer an aircraft engine to survive the 0.001% (or whatever it is) chance birdstrike that results in a 'blade off', but then it would be over engineered, which would make it more complex, heavier, more expensive, etc, etc....

It therefore makes more sense to invest an amount of effort into developing a procedure, or 2 for such instances.

Spaceflight is inherently complex, and it's not exactly undertaken lightheartedly. Things fail, despite everyone's best efforts.

[Eric Mc]

I do think they cut the margins too tight with the Shuttle though. There were virtually no survivable abort modes during launch. At least with Mercury, Apollo and Soyuz the crews had a fighting chance of making it if something went wrong with a booster.

[Simpo Two]

Eric Mc said:

At least with Mercury, Apollo and Soyuz the crews had a fighting chance of making it if something went wrong with a booster.

Did any crews have to abort after take-off? I can't think of any. And all done with cogs and rubber bands!

[bitchstewie]

Simpo Two said:

Did any crews have to abort after take-off? I can't think of any. And all done with cogs and rubber bands!

I don't believe so.

These guys did https://www.youtube.com/watch?v=b7bDIRmNDcM

[Eric Mc]

Simpo Two said:

Eric Mc said:

At least with Mercury, Apollo and Soyuz the crews had a fighting chance of making it if something went wrong with a booster.

Did any crews have to abort after take-off? I can't think of any. And all done with cogs and rubber bands!

Nobody on Mercury or Apollo ever had to make use of the abort system but it has definitely been used on Soyuz - and it worked.

[damon80]

For anyone who is interested in the history of the Shuttle and its first flight, I cannot recommend "Into the Black" by Rowland White highly enough. The same chap who wrote "Vulcan 607".

I never read novels - only the odd auto-biography, or non-fiction piece, so I am by no means a Sunday Times critic, but by Jove this is a fantastic read.

[Eric Mc]

I've just finished reading it again - for the second time. It's excellent.

Other Shuttle books worth reading are -

"Riding Rockets" - Mike Mullane



"Bold They Rise" - Nebraska Press -



"Wheel Stop" - Nebraska Press -



Haynes Space Shuttle Manual



This book is just out and might be worth a read. In fact, Massimino is a guest on Radio 4 this morning between 9.00 and 10.00 am.

Edited by Eric Mc on Saturday 29th October 18:07

[damon80]

I've read Riding Rockets, but the others are a new one on me - cheers for the heads up

[Eric Mc]

I've edited my previous post to insert the correct cover picture for the Haynes Space Shuttle manual.

The Nebraska Press books are available through US Amazon and, as a result, aren't particularly cheap.