How do Solid Fuel Upperstages work?

[DaveS]

There was nothing particularly secret about it. It's been a well known fact since the start of manned spaceflight that the RSO has the authority to terminate manned vehicles if they deem it to be outside it's safety envelope. The SRB from Challenger was destroyed as it's predicted course took it near a coastal town.

(edit) Nvm, it's listed in a paper so isn't covered by itar.

Secret? Heck no! There's lots of tracking camera video of both the SRBs being destructed by the RSO available on the Internet.

It's nothing spectacular to see really. Just a very brief flash and the flames from the boosters disappear from view.

 

[spcefrk]

ICBM interceptors go through whats called an Energy Abatement Maneuver. They fly in circles --the track looks like a spiral, to bleed excess energy. See

 

[Andy44]

That's not an energy abatement maneuver! It's a failure of an SLBM test. Well documented.

What you're looking for is video of missiles being launched at the Nevada test range, where that maneuver is performed to make sure the missile cannot leave the range.

 

[spcefrk]

That's not an energy abatement maneuver! It's a failure of an SLBM test. Well documented.

What you're looking for is video of missiles being launched at the Nevada test range, where that maneuver is performed to make sure the missile cannot leave the range.

That was not the original picture I used. I went looking for a good picture for a missile defense paper back in 1999 and found one similar to that but not so near the ground :lol:. I read more about the picture and learned it was an energy abatement maneuver. I guess this picture was not showing the same type of event....

 

[tblaxland]

Mass properties changes during rocket burns
is one major real world annoyance that isn't simulated
much or not at all in Orbiter yet, I believe.

Simulation of this is vessel dependent. Correct me if I'm wrong, but I think SSU supports mass/centre of gravity changes. Also, the Ananke momentum exchange tether that I am working on with n0mad23 includes a reasonably detailed mass model that changes vessel mass/centre of gravity/PMIs as fuel is used and/or tether is reeled (the code exists but is not yet used because thrusters and reeling have not been implemented yet).

EDIT: Mass is changed automatically by Orbiter. Centre of gravity/PMIs is not.

 

[simonpro]

Andy, Spacefrk: Didn't you have exactly this dicussion last time you posted that picture?

 

[John_L]

I think the one thing not mentioned is that each segment of the booster burns (from bottom to top) with the exhaust escaping through channels between an inner and outer casing. Where the segments meet, there are the famed O-rings that failed, thus allowing the hot gases to escape, and ultimately burn though and rupture the ET. So an SRB is not a big 'estes' rocket, although NASA likes to describe them as such, rather a pretty complicated hunk of rocket. For reasons unknown to me, separation before the rockets are 'finished' burning is not possible. You're along for the ride until the end.

 

[simonpro]

The way SRB sep works you'd be likely to get the SRB exhaust right up against the ET or the Orbiter if you tried to separate before they'd burned out.

 

[Urwumpe]

I think the one thing not mentioned is that each segment of the booster burns (from bottom to top) with the exhaust escaping through channels between an inner and outer casing. Where the segments meet, there are the famed O-rings that failed, thus allowing the hot gases to escape, and ultimately burn though and rupture the ET. So an SRB is not a big 'estes' rocket, although NASA likes to describe them as such, rather a pretty complicated hunk of rocket. For reasons unknown to me, separation before the rockets are 'finished' burning is not possible. You're along for the ride until the end.

Wrong. The SRB fuel surrounds just a round channel, and burns from inside to outside. The fuel does not burn from bottom to top like inside a fireworks rocket. Around the ignitor of the SRB, the fuel has a star shaped cross section to accelerate ignition (bigger contact surface) and create more thrust during lift-off.

The exhaust can enter in the gaps between two fuel segments, and finally reach the O-Rings that way.

A separation before the rockets are expended is possible - but not recommended, when the remaining shuttle is still too heavy, it can't even make a contingency abort. The booster separation motors of the SRBs are designed to allow a safe separation in any situation during ascent.


-----Posted Added-----

That was not the original picture I used. I went looking for a good picture for a missile defense paper back in 1999 and found one similar to that but not so near the ground :lol:. I read more about the picture and learned it was an energy abatement maneuver. I guess this picture was not showing the same type of event....

A energy abatement maneuver looks more like a corkscrew, deflecting thrust off-trajectory.

This one shows the diameter of the spiral decreasing, which means that the rotation speed increased faster as the vessel gained velocity.

 

[spcefrk]

Andy, Spacefrk: Didn't you have exactly this dicussion last time you posted that picture?

I don't think I've ever posted a picture like that here. :shrug:

 

[Urwumpe]

A controlled energy abatement maneuver.

 

[spcefrk]

A controlled energy abatement maneuver.

:speakcool: Much better! Danke!

 

[thegrogen]

Also, i don't know any launch vehicle which uses solid rocket boosters to place its payload in orbit. Solid rocket boosters usually are only used for lift off / first stages because they provide more thrust at lift off compared to liquid propulsion, reduce the mass of the launch vehicle and are a little more "easy" to handle compared to liquid propulsion (but also risky in a few aspects). Usually it is upper stages of rockets which boost payloads into orbit. Solid boosters just act as a catapult during launch and initial ascent.

But I might be wrong. Please correct me if there is a different launch vehicle meanwhile I didn't hear from yet.

Both Orbital's Pegasus and Taurus rockets use all-solid systems.

http://en.wikipedia.org/wiki/Pegasus_XL
http://en.wikipedia.org/wiki/Taurus_rocket

That is assuming that you mean "solid rocket motors" by "solid rocket boosters".

 

[Hashy]

Ok im stopping reading this thread.. Since every other post is a, you are wrong, no you are wrong...

So because of this, all the facts I have read here in the last 5 minutes I must presume inaccurate.. Thx guys =D

Energy abladive maneuvre blowing up challenger or something like that.... hahaha =p

 

[MajorTom]

Wrong. As Urwumpe said, all you need to do is blow out ports on the booster that will allow the chamber pressure to drop fast enough, and the flame goes out. No flame == no thrust.

Google 'thrust termination' and you'll probably find a few documents on the subject; there's nothing relevant available as a PDF on NTRS. I found numerous references to Minuteman missiles having thrust termination ports on the third stage to shut down the solid rocket when it reached the correct delta-V, but no images and not much detail.

Jackpot! Thanks movieman! :speakcool:

I've been assembling a new Minuteman II / III add-on. The problem of controlling the final trajectory has been bothering me...you've got solid rockets in all three stages, but you must be able to cut off the third stage precisely. There is a Google books result that does go into some detail on this process:

http://books.google.com/books?id=mU...&hl=en&sa=X&oi=book_result&resnum=7&ct=result

...and I wouldn't have found this without your lead. :thumbsup:

To summarize, yes, explosives are wound into the sidewalls of the third stage of the various Minutemen that vent the combustion chamber, temporarily producing a negative thrust that causes stage 3 to drop away from the post boost vehicle (containing the warhead, penetration aids and other stuff).

For those interested in this add-on development, I'll continue this topic in another thread which I'll add a link to later.

Ciao

MT