Defense Against (Model) Rockets

Although we had a lively thread last spring over the new BATFE rules to
protect us from terrorists bearing model rockets, this article in
Homeland Defense Journal raises the issue once again.

http://www.homelanddefensejournal.com/scoop_dircm.htm

" There are two terrorist scenarios that can defeat the use of DIRCM,
and should be considered:
• Rocket-propelled grenade
• Alternative missile guidance technologies, such as a two-stage
high-powered model rocket equipped with radio frequency or global
positioning system technology"

I especially like this comment.

"The lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."

Exponential increase? Yeah, right. At least I know not to send my kids
to Case Western if they want to get an engineering degree.

ND

Mike Sabo wrote:
I especially like this comment.

"The lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."

Exponential increase? Yeah, right. At least I know not to send my kids
to Case Western if they want to get an engineering degree.

Please let me know which University you attended so I can keep my kids
from going there.

Or to put it simply; Look up what kinds of fuses 'real' _AM's use and
why.

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

Text-Only Version:
http://www.io.com/~o_m/columbia_loss_faq.html

Enhanced HTML Version:
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Corrections, comments, and additions should be
e-mailed to , as well as posted to
sci.space.history and sci.space.shuttle for
discussion.

"Mike Sabo" wrote in message
...

"The lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."

8) One of my pet peeves is seeing "exponential increase" in popular media.
It seems that anything that is bigger can be referred to as an "exponential
increase". Which I guess is tautologically true, in that there exists a base
for an exponential function such that any increase can be modelled as an
exponential increase... speshly easy if only two data points are used.

---
Dave Boll
http://www.daveboll.com/

Saw the site, the guy's another nutter.

In article ,
"Dave & Janelle" wrote:

8) One of my pet peeves is seeing "exponential increase" in popular media.
It seems that anything that is bigger can be referred to as an "exponential
increase". Which I guess is tautologically true, in that there exists a base
for an exponential function such that any increase can be modelled as an
exponential increase... speshly easy if only two data points are used.

It bugs me less than using "quantum leap" to mean a big jump (as opposed
to its true meaning, a jump that's almost inconceivably small).

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| http://www.macwebdir.com |
`------------------------------------------------------------------'

Dave & Janelle wrote:
"Mike Sabo" wrote in message
...


"The lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."


8) One of my pet peeves is seeing "exponential increase" in popular media.
It seems that anything that is bigger can be referred to as an "exponential
increase". Which I guess is tautologically true, in that there exists a base
for an exponential function such that any increase can be modelled as an
exponential increase... speshly easy if only two data points are used.

---
Dave Boll
http://www.daveboll.com/


This seems to be a common error. Even Discover Magazine did this:
http://www.discover.com/issues/aug-03/cover/
About a third of a way down under "Laser Sail":
"But the strength of sunlight falls off exponentially with distance, so
solar sails do not work far away from the sun."

Inverse square may be rapid but not quite exponential.

IMO it was a very good article even though it did have that mistake.

--
Hop David
http://clowder.net/hop/index.html

Derek Lyons wrote:
Mike Sabo wrote:

I especially like this comment.

"The lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."

Exponential increase? Yeah, right. At least I know not to send my kids
to Case Western if they want to get an engineering degree.

Please let me know which University you attended so I can keep my kids
from going there.

Not a problem Mr. Lyons. I wouldn't base such a decision on a sample
size of n=1. I can see where my sentence was pretty hot. UIUC as of next
spring.

Or to put it simply; Look up what kinds of fuses 'real' _AM's use and
why.

Yes, they use proximity Fuzes. In this case, are you not trading off an
already miniscule warhead size for something even smaller but with a
proximity fuze? The author's premise is that you already have a guidence
system that will lead the rocket to the bottom of the cargo bay,
"expontially" increasing the probability of a direct hit in that area.
Won't the Wonder Weapon with a size X warhead against the skin of the
cargo bay have a greater potential for causing damage than one with a
size X-Y at 2 meters +/- Z below the cargo bay?

D.

"Joe Strout" wrote in message
...
In article ,
"Dave & Janelle" wrote:

8) One of my pet peeves is seeing "exponential increase" in popular
media.
It seems that anything that is bigger can be referred to as an
"exponential
increase". Which I guess is tautologically true, in that there exists a
base
for an exponential function such that any increase can be modelled as an
exponential increase... speshly easy if only two data points are used.

It bugs me less than using "quantum leap" to mean a big jump (as opposed
to its true meaning, a jump that's almost inconceivably small).

But that's a misunderstanding of the historical origins of the term.

While compared to our everyday "macro" lives, quantum
transitions are small, that's not inherent to the concept -- it's
simply how the subatomic physics worked out.

The point about a quantum leap is that it is a quantized transition,
from one state to another, WITHOUT an intervening state. If
you look at it another way, regular leaps can be infinitessimally
small, but a quantum leap is by definition a much larger set size.

When people talk about "quantum leap" in macro terms, they
are not meaning that it's a big jump per se. It's just that there
are not any INTEVENING steps that would create a more
gradual transition. A new processor that makes computers 10
times faster is a quantum leap over the usual 2 times faster
pace of change. Of courese, this is all subjective and relative;
you can always reduce the scale and call ordinary transitions
quantum compared to even more gradual progress...

So, quantum leaps aren't per se big or small... they are just
larger than an alternative, more gradual, progress that may
have been expected.

Bruce

In article ,
Mike Sabo wrote:
Won't the Wonder Weapon with a size X warhead against the skin of the
cargo bay have a greater potential for causing damage than one with a
size X-Y at 2 meters +/- Z below the cargo bay?

If the former can be achieved, yes. But in practice, that is formidably
difficult, and the alternative to a proximity fuze is usually no explosion
at all because you missed.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

(Derek Lyons) wrote in message ...
Mike Sabo wrote:
I especially like this comment.

"The lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."

Exponential increase? Yeah, right. At least I know not to send my kids
to Case Western if they want to get an engineering degree.

Please let me know which University you attended so I can keep my kids
from going there.

Or to put it simply; Look up what kinds of fuses 'real' _AM's use and
why.


The Homeland Defense Journal author says:

"terrorists may use a two-stage high-powered model rocket,
*readily available to sport rocketry enthusiasts*, equipped with
radio frequency (RF) or global positioning system (GPS) guidance
technology, instead of the infrared technology, which DIRCM is
designed to defeat."

"Radio or GPS beacons, in the form of cellular phones or portable
radios, hidden in the cargo bay of the aircraft will act as
transceivers guiding the model rocket straight to its target. The
lethality of such a system would be exponentially increased if the
miniature rocket payload section would house a proximity explosive
charge, instead of a grazing or impact warhead."


My question is: exponential of what? Of kill rate? Of kill
radius? Of kill probability versus range?

AIM-9B Sidewinders with proximity fuses had a 16% kill rate
against Migs during Vietnam (28 kills for 175 missiles fired).
Without prox fuses what might the kill rate have been?

According to http://www.history.navy.mil/faqs/faq96-1.htm
about the proximity fuze developments during WW II that were
probably responsible for the defeat of Japan's air power:

"Analyses of action reports indicate that the effectiveness
of radio proximity fuzes as compared to mechanical time fuzes
in antiaircraft fire is about the order of a 3-to-1 improvement
for the proximity fuzes."

Granted this is for shellfire, not missile fire, but it provides
a hint that the missile improvement might be in the 10-to-1 range.
Apply this to the AIM-9B and you predict less than 3 kills in
175 tries for a non-prox fuse.

Back to the "exponential of what?" question. Well, I can see
that exp(2.3) = 10 = kill rate improvment. There's an
exponential, but what does 2.3 signify?! What about
kill radius? The kill radius (guessing roughly) has probably
increased from 1 foot to 100 feet, and we all know that
exp(4.605) = 100. Another exponential! What about kill
probability versus range to target? I bet, if you plotted it
out real nice, the curve would look like some kind of
exponential-based function.

The exponential thing has me scratching my head, but my main
problem with this author is his claim that these two-stage,
high-powered model rockets that are "readily available to the
sport rocketry enthusiasts" (such people must surely be
"evil-doers" since they aren't using their skills to analyze
weapons systems on the internet) can somehow be made violently
steerable (to many Gs by the way) and capable of carrying 10s
of pounds of payloads while doing so. To the best of my
knowledge, no steerable high-power rockets of the type imagined
by this author exist. He must not know that most such rockets
are composed of glued-together pieces of paperboard or fiberglass
composite body tubes. I've seen a lot of high-powered amateur
rockets fly, some that weighed more than 100 pounds even, but
I've never seen one that steered, or attempted to steer. In
fact, trying to make such a rocket steer is a violation of the
sport's safety codes. In fact, one needs a BATF permit to even
buy or possess a non-steerable high powered rocket motor - and
such motors hardly ever burn for more than just a few seconds
(in other words, they are powered for no more than a few hundred
feet, then they coast).

Odd that Homeland Defense Journal is concerned about the
serious terrorist model rocketeers but not so worried about
rouge deer hunters (those suspicious people with their pickup
trucks and their beer and their funny hats and plaid shirts)
who could easily threaten low flying passenger jets with high
powered rifles. {Which brings to mind an odd image of some
kind of dual between deer hunters and model rocket enthusiasts
- my money would be on the hunters (they've killed before,
you see).}

Odd too that the Journal would think it more likely that the
terrorists (these were the box cutter guys, remember?) would
go to all the trouble of developing the complex steerable
guided proximity fused killer model rocket rather than simply
firing a dense pattern of much simplier and less expensive
unguided rockets (drive a paper-roof van filled with prewired
rocket launch racks aimed straight up beneath the landing
pattern. When you hear the whine of the engines, push the
button).

Sorry for the rant. I started small, but my message suddenly,
and inexplicably, exponentially increased in wordage.

- Ed Kyle