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Model Forum / General / Rockets / March 2010



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29/40 question?

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dave.harper - 11 Mar 2010 19:05 GMT
I'm looking to get some higher powered casings, but had a question
about the 29/40-120 system I already have.  Specifically, what does
the "40" stand for?  There's also 18/20 and 24/40... what's the "20"
and "40" mean?  Is it thread related?

Based on previous threads, it also looks like I might need different
closures for 29-180 and 29-240.  Is this correct?

Thanks in advance!
Dave
Jonathan Sivier - 11 Mar 2010 19:30 GMT
>I'm looking to get some higher powered casings, but had a question
>about the 29/40-120 system I already have.  Specifically, what does
>the "40" stand for?  There's also 18/20 and 24/40... what's the "20"
>and "40" mean?  Is it thread related?

  The numbers have nothing to do with the threads on the casings.  The first
number refers to the diameter of the casing in millimeters and the second number
is the approximate number of newton-seconds of the reloads it will hold.

  Thus the 18/20 is 18 mm in diameter and will hold 20 nt-sec "D" reloads.  The
24/40 casing is 24 mm and hold 40 nt-sec "E" reloads, though they also make "D"
and very light "F" reloads that work in this casing as well.  The 29/40-120 is a
29 mm casing for which they make "E", "F" and 120 nt-sec "G" loads.

>Based on previous threads, it also looks like I might need different
>closures for 29-180 and 29-240.  Is this correct?

  This is correct.  The 29/40-120 casing uses different closures than the other
line of 29 mm casings.  For these though there are a large number of sizes of
tubes which all work with the same closures, so you can have one set of closures
and they will work with any of the tubes which hold, depending on their length,
reloads from 60 to 360 nt-secs.

  It also happens that the newer 24/60 case uses different closures than the
24/40 case.

Jonathan
-----
Jonathan Sivier
Secretary, Central Illinois Aerospace
jsivier AT illinois.edu
NAR #56437 | Tripoli #1906
CIA Web Site: http://www.CIARocketry.org/
Home Page: https://netfiles.uiuc.edu/jsivier/www/
dave.harper - 11 Mar 2010 20:05 GMT
Ah, thanks.  The "40" is a little bit of a misnomer then, since the
29/40-120 will hold some G's that go up to ~120 NS.

Thanks,
Dave

> >I'm looking to get some higher powered casings, but had a question
> >about the 29/40-120 system I already have.  Specifically, what does
[quoted text clipped - 30 lines]
> CIA Web Site:http://www.CIARocketry.org/
> Home Page:https://netfiles.uiuc.edu/jsivier/www/
 
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