Explosive bolts question

[Lobster Man]

This isn't a specific-Shuttle question, but since this group has a bit
more traffic than some of the other sci.space groups, and explosive
bolts are still used (I think...) on Shuttle, I'll ask it here.

Been watching some old NASA Mercury program footage that's available now
on DVD. Last night I was watching the Little Joe launches. Great stuff!
Some of the footage was of the manual build process for the boilerplate
Mercury capsules tested with the various Little Joe launches.

Anyway, at one point they showed a collar that held the boilerplate to
the booster. And the voice-over of the footage didn't really discuss how
the two separated. I assumed they used explosive bolts to hold the
collar together, and that got me to wondering about exactly how
explosive bolts work.

Are they standard bolts like in other industries, but with some quantity
of explosives attached to force them to fail at detonation? Or are they
perhaps hollowed out and the explosive material is inside? I would
figure that the first might not separate in all instances, and the
second might be too prone to detonate at times of stress.

So... all the experts that are here: what's the exact nature of these
essential components?

Thanks in advance.

[OM]

Post by Lobster Man
This isn't a specific-Shuttle question, but since this group has a bit
more traffic than some of the other sci.space groups, and explosive
bolts are still used (I think...) on Shuttle, I'll ask it here.
Been watching some old NASA Mercury program footage that's available now
on DVD. Last night I was watching the Little Joe launches. Great stuff!
Some of the footage was of the manual build process for the boilerplate
Mercury capsules tested with the various Little Joe launches.
Anyway, at one point they showed a collar that held the boilerplate to
the booster. And the voice-over of the footage didn't really discuss how
the two separated. I assumed they used explosive bolts to hold the
collar together, and that got me to wondering about exactly how
explosive bolts work.
Are they standard bolts like in other industries, but with some quantity
of explosives attached to force them to fail at detonation? Or are they
perhaps hollowed out and the explosive material is inside? I would
figure that the first might not separate in all instances, and the
second might be too prone to detonate at times of stress.
So... all the experts that are here: what's the exact nature of these
essential components?

[Rusty]

Article detailing the use of explosive bolts by NASA:
http://media.nasaexplores.com/lessons/01-032/fullarticle.pdf

[/Rusty]

OM

[Lobster Man]

Post by OM

Post by Lobster Man
This isn't a specific-Shuttle question, but since this group has a bit
more traffic than some of the other sci.space groups, and explosive
bolts are still used (I think...) on Shuttle, I'll ask it here.
Been watching some old NASA Mercury program footage that's available now
on DVD. Last night I was watching the Little Joe launches. Great stuff!
Some of the footage was of the manual build process for the boilerplate
Mercury capsules tested with the various Little Joe launches.
Anyway, at one point they showed a collar that held the boilerplate to
the booster. And the voice-over of the footage didn't really discuss how
the two separated. I assumed they used explosive bolts to hold the
collar together, and that got me to wondering about exactly how
explosive bolts work.
Are they standard bolts like in other industries, but with some quantity
of explosives attached to force them to fail at detonation? Or are they
perhaps hollowed out and the explosive material is inside? I would
figure that the first might not separate in all instances, and the
second might be too prone to detonate at times of stress.
So... all the experts that are here: what's the exact nature of these
essential components?

[Rusty]
http://media.nasaexplores.com/lessons/01-032/fullarticle.pdf
[/Rusty]
OM

Thanks!

[Rusty]

Post by Lobster Man
Thanks!

For detailed info........

--------------------------------------------------------------------------------------------------------------
A Manual for Pyrotechnic Design, Development and Qualification

Bement, Laurence J.; Schimmel, Morry L.
NASA Langley Research Center

Although pyrotechnic devices have been singularly responsible for the
success of many of the critical mechanical functions in aerospace
programs for over 30 years, ground and in-flight failures continue to
occur. Subsequent investigations reveal that little or no quantitative
information is available on measuring the effects on performance of
system
variables or on determining functional margins. Pyrotechnics are
considered to be readily available; and, therefore, can be managed by
any subsystem in which they are applied, such as structure, propulsion,
electric power, or life support. The primary purpose of this manual is
to alter the concept that the use of pyrotechnics is an art and refute
'justifications' that applications do not need to be understood by
providing information on pyrotechnic design, development, and
qualification on an engineering basis. Included are approaches to
demonstrate functional reliability with less than 10 units, how to
manage pyrotechnic-unique requirements, and methods to assure that the
system isproperly assembled and will perform the required tasks.
NASA-TM-110172

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19950024937_1995124937.pdf

--------------------------------------------------------------------------

Report on Alternative Devices to Pyrotechnics on Spacecraft; 10th
Annual AIAA/USU Conference on Small Satellites

Lucy, M.; Hardy, R.; Kist, E.; Watson, J.; Wise, S.
NASA Langley Research Center
2005-04-29T17:17:46Z; 2005-04-29T17:17:46Z; 1996-09-16; 1996-09-16;
1996-09-19
Pyrotechnics accomplish many functions on today's spacecraft,
possessing minimum volume/weight, providing instantaneous operation on
demand, and requiring little input energy. However, functional shock,
safety, and overall system cost issues, combined with emergence and
availability of new technologies question their continued use of space
missions.

http://library-dspace.larc.nasa.gov/dspace/jsp/bitstream/2002/11268/1/NASA-96-10css-mhl.pdf


--------------------------------------------------------------------------

Independent Orbiter Assessment (IOA): Assessment of the pyrotechnics
subsystem
Robinson, W. M.
NASA Center for AeroSpace Information (CASI)
NASA-CR-185531; NAS 1.26:185531; REPT-1.0-WP-VA88005-05 , 19880205; Feb
5, 1988 The results of the Independent Orbiter Assessment (IOA) of the
Failure Modes and Effects Analysis (FMEA) and Critical Items List
(CIL) are presented. The IOA effort first completed an analysis of the
Pyrotechnics (PYRO) hardware, generating draft failure modes and
potential critical items. To preserve independence, this analysis was
accomplished without reliance upon the results contained within the
NASA FMEA/CIL documentation. The IOA results were then compared to the
NASA FMEA/CIL baseline with proposed Post 51-L updates included. A
resolution of each discrepancy from the comparison is provided through
additional analysis as required. This report documents the results of
that comparison for the Orbiter Pyrotechnics hardware.
Accession ID: 90N10946
Document ID: 19900001630

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900001630_1990001630.pdf


--------------------------------------------------------------------------


-Rusty

[Pat Flannery]

Rusty wrote:

The guy to get going on this matter is Mr. Richard Katz.
AKA- Mr. Stray Voltage. :-)

Pat

[OM]

Post by Lobster Man

Post by OM

Post by Lobster Man
So... all the experts that are here: what's the exact nature of these
essential components?

[Rusty]
http://media.nasaexplores.com/lessons/01-032/fullarticle.pdf
[/Rusty]
OM

Thanks!

...No prob. Rust assured, Resty...er...Rest assured, Rusty will be
along shortly to add more PDF links :-P

OM

[Joe Delphi]

Post by Lobster Man
This isn't a specific-Shuttle question, but since this group has a bit
more traffic than some of the other sci.space groups, and explosive bolts
are still used (I think...) on Shuttle, I'll ask it here.
So... all the experts that are here: what's the exact nature of these
essential components?
Thanks in advance.

In the case of the shuttle, I don't think its the bolt that explodes, I
think its the nut holding that bolt that explodes, but I may be wrong.

The engineering term is "frangible".

Google on the following terms: Frangible Bolts, Frangible Nuts, Frangible
hardware, "NASA Standard Initiator".....etc

Many hardware items are frangible (designed to break in certain
conditions) - for example, the approach lights at the end of most airport
runways are mounted on frangible stanchions so that if an airliner is coming
in too low and hits one with its landing gear, it will break the stanchion
and not the airliner. Same for many of the sign posts and street lights
next to highways.

JD

[Reunite Gondwanaland (Mary Shafer)]

On Sat, 9 Sep 2006 17:58:46 -0700, "Joe Delphi"

Post by Joe Delphi
Many hardware items are frangible (designed to break in certain
conditions) - for example, the approach lights at the end of most airport
runways are mounted on frangible stanchions so that if an airliner is coming
in too low and hits one with its landing gear, it will break the stanchion
and not the airliner. Same for many of the sign posts and street lights
next to highways.

It's supposed to be all the posts and lights and stuff by the side of
the road now. The USAF went around and re-did all their signs with
little chunks of box beam slightly bigger than the posts themselves as
sleeves. They cut the posts at ground level, secured the above-ground
portion to the sleeve with a single bolt that would fail on impact,
and dropped the other end of the sleeve over the embedded portion of
the post.

They then discovered that with enough stop-sign flutter from high
winds the frangible fitting would "frange", so they had to stiffen the
posts to reduce the flutter. They could do so safely though, because
they no longer had to use flimsy posts, which they had used to reduce
risk of damage and injury in case of an impact. The old posts had
been sort of semi-frangible.

Mary "Seems sort of counter-intuitive"

[OM]

On Sun, 08 Oct 2006 22:40:11 -0700, "Reunite Gondwanaland (Mary

Post by Reunite Gondwanaland (Mary Shafer)
They then discovered that with enough stop-sign flutter from high
winds the frangible fitting would "frange", so they had to stiffen the
posts to reduce the flutter. They could do so safely though, because
they no longer had to use flimsy posts, which they had used to reduce
risk of damage and injury in case of an impact. The old posts had
been sort of semi-frangible.

...Boy, and I thought that last post was innuendo fodder! :-) :-) :-)
:-P

OM

[Danny Dot]

Post by Lobster Man
This isn't a specific-Shuttle question, but since this group has a bit
more traffic than some of the other sci.space groups, and explosive bolts
are still used (I think...) on Shuttle, I'll ask it here.
Been watching some old NASA Mercury program footage that's available now
on DVD. Last night I was watching the Little Joe launches. Great stuff!
Some of the footage was of the manual build process for the boilerplate
Mercury capsules tested with the various Little Joe launches.
Anyway, at one point they showed a collar that held the boilerplate to the
booster. And the voice-over of the footage didn't really discuss how the
two separated. I assumed they used explosive bolts to hold the collar
together, and that got me to wondering about exactly how explosive bolts
work.
Are they standard bolts like in other industries, but with some quantity
of explosives attached to force them to fail at detonation? Or are they
perhaps hollowed out and the explosive material is inside? I would figure
that the first might not separate in all instances, and the second might
be too prone to detonate at times of stress.
So... all the experts that are here: what's the exact nature of these
essential components?
Thanks in advance.

--
Danny Dot wrote:

One form of explosive "bolts" is the linear shaped charge.
http://en.wikipedia.org/wiki/Shaped_charge
Imagine a long rectangular cross section of some type of explosive. Now cut
a v shape down the length of the explosive. Now line the sides of the v
with "anything" (copper, glass, etc.). When you fire the explosive the
nature of the v shape is the lining material is melted and is expelled at
very high velocity. Basically a cutting torch.

This is used in the range safety devices to open the shuttles solid rocket
boosters. NASA used to have a linear shape charge on the External Tank, but
we took it off. This system was used in the F-111 escape system that took
the crew cabin during an ejection. They are used in demolition to cut
beams, etc.

On a side note, the Japanese had a "Bonsai Sick" in WWII. It had a cylinder
shaped charge on the end of a stick. It was employed by a person running up
to the tank and poking the stick on the side of the tank. The shape charge
would kill the tank, and the blast killed the person holding the stick. It
is amazing we won the war against a country with that much will to fight!!!


Look at my site and see how NASA treats a creative mind!!!
The summary is "Not Very Well" :-)
www.mobbinggonemad.org