loughry@tramp.Colorado.EDU (J. Loughry) (12/02/89)
How do "explosive bolts" actually work? Do they contain an internal charge with a detonator (sounds like a recipe for a fragmentation grenade--not a good thing to have bouncing around the pad during a launch), or is it an external shaped charge (like a bolt cutter)? How do they contain fragments? ------------------------------------------------------------------------------ J. Loughry University of Colorado loughry@tramp.colorado.edu ------------------------------------------------------------------------------
henry@utzoo.uucp (Henry Spencer) (12/02/89)
In article <14459@boulder.Colorado.EDU> loughry@tramp.Colorado.EDU (J. Loughry) writes: >How do "explosive bolts" actually work? Do they contain an internal charge >with a detonator (sounds like a recipe for a fragmentation grenade--not a good >thing to have bouncing around the pad during a launch), or is it an external >shaped charge (like a bolt cutter)? How do they contain fragments? Normally it's an internal charge, with detonator, that is large enough to reliably crack the bolt when fired. Blowing the thing to bits is not necessary; it suffices to break it at a pre-supplied weak area. Fragment containment depends on details of the situation. In the case of the shuttle, I made a mistake earlier: the solid bolts are on the SRB skirts, not the pad. The explosive nuts are located in housings on the pad, which tend to contain the fragments. -- Mars can wait: we've barely | Henry Spencer at U of Toronto Zoology started exploring the Moon. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
steve@nuchat.UUCP (Steve Nuchia) (12/02/89)
In article <14459@boulder.Colorado.EDU> loughry@tramp.Colorado.EDU (J. Loughry) writes: >How do "explosive bolts" actually work? Do they contain an internal charge >with a detonator (sounds like a recipe for a fragmentation grenade--not a good >thing to have bouncing around the pad during a launch), or is it an external >shaped charge (like a bolt cutter)? How do they contain fragments? I found a book on industrial pyrotechnics in a used bookstore a while back -- lots of space stuff in it. It's on loan at the moment though... check your library. Anyway, the technical term is "frangible" bolts and nuts. The mechanical part is designed with a cavity for the explosive charge and a controlled weak spot. Frangible nuts, which seem to be used more than bolts, have two or more charges and fracture zones. They thread onto a stud like a regular nut, then when the charges detonate the nut breaks into pieces and (falls, flies) out of the way. Frangible bolts are generally designed to break near the shear line, although one may want to have the weak spot farther inside one of the structures. Anyway, the charges are sized to make the part stop functioning as a fastener, and the fastener is designed to make that take as little energy as is practical. Hardly a recipe for a grenade -- they do not fragment and the exit velocities are controlled. And besides, with a few million pounds of SRB thrust in the neighborhood, who's going to notice a couple of grenades? Other interesting pryo devices described in the book include the guillotine (sp?) used to sever the cables between the Apollo CM and CSM and the linear charge installed in the first few shuttle flights to open up the sunroof for the ejection seats. -- Steve Nuchia South Coast Computing Services (713) 964-2462 "Man is still the best computer that we can put aboard a spacecraft -- and the only one that can be mass produced with unskilled labor." - Wernher von Braun
cdaf@iuvax.cs.indiana.edu (Charles Daffinger) (12/03/89)
In article <1989Dec2.104842.22624@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
o Normally it's an internal charge, with detonator, that is large enough to
o reliably crack the bolt when fired. Blowing the thing to bits is not
o necessary; it suffices to break it at a pre-supplied weak area.
What happens should one of these charges fail to detonate? Will a
single bolt be able to hold the shuttle down long enough to cause
disaster, or is a single bolt insignificant enough that it would break
without affecting the launch? How many of these bolts actually hold
the shuttle?
-charles
--
Charles Daffinger >Take me to the river, Drop me in the water< (812) 339-7354
cdaf@iuvax.cs.indiana.edu {pur-ee,rutgers,pyramid,ames}!iuvax!cdaf
Home of the Whitewater mailing list: whitewater-request@iuvax.cs.indiana.eduKDA101@PSUVM.BITNET (KeithPetto Alexander) (12/03/89)
In article <30704@iuvax.cs.indiana.edu>, cdaf@iuvax.cs.indiana.edu (Charles Daffinger) says: > >What happens should one of these charges fail to detonate? Will a >single bolt be able to hold the shuttle down long enough to cause >disaster, or is a single bolt insignificant enough that it would break >without affecting the launch? How many of these bolts actually hold >the shuttle? Someone mentioned this occurrence just the other day. It seems one of the bolts did fail to detonate during a shuttle launch. It did not, however, stand a chance of holding the shuttle back. I believe there only minimal damage was sustained. Once the SRBs are ignited it certianly takes more than one of those bolts to hold the shuttle down. Does anyone know how many bolts would be needed to hold the shuttle back, or is that never considerd as an alternative to launch at that point? ------- Petto :-> "The opinions expressed above may or may not be my own." kda101@psuvm.bitnet
henry@utzoo.uucp (Henry Spencer) (12/03/89)
In article <16890@nuchat.UUCP> steve@nuchat.UUCP (Steve Nuchia) writes: >I found a book on industrial pyrotechnics in a used bookstore a while >back -- lots of space stuff in it. It's on loan at the moment though... >check your library. I (and I suspect a lot of other people) would be interested to see a more specific reference, i.e. title and author, once you get it back. -- Mars can wait: we've barely | Henry Spencer at U of Toronto Zoology started exploring the Moon. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
henry@utzoo.uucp (Henry Spencer) (12/03/89)
In article <30704@iuvax.cs.indiana.edu> cdaf@iuvax.cs.indiana.edu (Charles Daffinger) writes: >What happens should one of these charges fail to detonate? Will a >single bolt be able to hold the shuttle down long enough to cause >disaster, or is a single bolt insignificant enough that it would break >without affecting the launch? I *think* a single bolt isn't enough to hold things down. Not sure. >How many of these bolts actually hold the shuttle? Well, they're not designed to hold the shuttle against SRB thrust at all. The nuts are blown simultaneously with SRB ignition. -- Mars can wait: we've barely | Henry Spencer at U of Toronto Zoology started exploring the Moon. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
steve@nuchat.UUCP (Steve Nuchia) (12/04/89)
In article <1989Dec3.022001.10691@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >>I found a book on industrial pyrotechnics in a used bookstore a while >I (and I suspect a lot of other people) would be interested to see a >more specific reference, i.e. title and author, once you get it back. No problem -- a quick phone call and ... Richard T. Barbour, Pyrotechnics in Industry McGraw Hill, N.Y. 1981 ISBN 0-07-003653-5 catalogue ref: TB270.B29 It is not a heavily mathematical, engineering kind of book, more of a gee-whiz picture book really, but I recommend it as the best book of its type I've come across. I learned a lot about the range of applications and the way charges are configured in practice, enough so I think I'd know what questions to asked if I needed to use pyrotechnics. -- Steve Nuchia South Coast Computing Services (713) 964-2462 "Man is still the best computer that we can put aboard a spacecraft -- and the only one that can be mass produced with unskilled labor." - Wernher von Braun
sjeyasin@dalriada.axion.bt.co.uk (swaraj jeyasingh) (12/07/89)
From article <1989Dec3.022001.10691@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): > In article <16890@nuchat.UUCP> steve@nuchat.UUCP (Steve Nuchia) writes: >>I found a book on industrial pyrotechnics in a used bookstore a while >>back -- lots of space stuff in it. It's on loan at the moment though... >>check your library. > > I (and I suspect a lot of other people) would be interested to see a > more specific reference, i.e. title and author, once you get it back. > -- Funnily enough, the first space book I ever read as kid had a pic and description of what an explosive bolt looked like and how it worked. This was the Ladybird book on ~How it works; The Rocket" (Age 9 upwards !) This was printed in 1967 and contains a fair (20pages) bit of rocket technology explained in very simple terms with lots of colour pics. Thoroghly recommend it for all budding rocket engineers. Dunno if it is available in the US though. They also do the same for: Nuclear power, Aeroplane, Ship etc (You might be amused to know that I picked up this little gem at our Church jumble sale in Malaysia (Borneo, in fact) way back in 72 !) I guess that's how "The Dream" travels Swaraj Jeyasingh sjeyasingh@axion.bt.co.uk British Telecom Research Labs Ipswich United Kingdom