piclist 1999\10\15\054859a >
www.piclist.com/techref/index.htm?key=
BY : Russell McMahon email (remove spam text)

From the PIC microprocessor list (believe it or not :-)
Copied  to ARocket for obvious reasons :-)

*** The story so far :-)
***     Is it "practical" to use rockets to stop a train?
***     (each wagon has own rockets)
***     (No, I didn't start this thread !)
***
***  Now, read on ......

Real world weight penalty would be more like 5 percent, coz:

1g for 5s should be adequate.
V= at = 32f/s/s * 5s = 160f/s = 110mph !!!!

Ever seen a train stop from 100mph in 5 seconds under brakes alone? :-)
(A Porsche will, almost)

Isp of around 250 is achievable (HTPB/AP/Al)
For 1g accn about 1/(Isp) x total (wagon + load + rocket) mass is burnt per
second

so Total mass/fuel mass required =
5/250/5 = 1/50th all up mass  = 2%

Actual motor weighs more than fuel but only about 10% for large solids.
So rocket = 2.2% of total mass.

If wagon mass = 20% of load mass (Anne ?) then  rocket =
2.2% x (120%/100%) = 2.6%ish

So 5% should be easily achievable

Thrust termination by blowout ports is a standard technique.

Multiple rockets per wagon would allow variable thrust levels.

But, I agree, it shouldnt be done (obviously).

Russell McMahon
_____________________________

>From another world - http://www.easttimor.com

What can one train-maniac* do?
Help the hungry at no cost to yourself!
at  http://www.thehungersite.com/

(* - or woman, child or internet enabled intelligent entity :-))

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