[SS-Propellant] SStS BEM test fired

Tue Jan 24 20:22:46 PST 2006

Congratulations with the SStS BEM test! The main objectives seem to have
been reached. I am looking forward to see the thrust curve and make some
simulations. From the design characteristics I am not too surprised that the
curve was close to expectation. Recent simulations indicate that below a
certain value (about 22.000.000 in metric units for KNSB) of  the product of
inner grain diameter x gas velocity x pressure , only limited erosion
occurs. Ones above this value the erosion becomes very important and is a
major cause of triangle shape thrust curves (athough triangle shape can also
be caused by poor ignition and very slow pressure built ip). As an example I
have attached the simulation of the NEAR SCA rocket motor which is an
excellent example of such a situation. The NEAR SCA 9901 motor is the
largest KNSB motor I know . The computer simulation is based on the burn
rate measurements from Richard (Nearsca2 ) and a kpn burning law (Nearsca1
k=0.0029 m/s  n=0.31) and can be compared with the actual measured thrust
(picture).  In the xls files the value of inner grain diameter x gas
velocity x pressure is  devided by 1.000.000. The trade off value hence is
22. One can see that during a large part of the curve we get much higher
values !
Some characteristics of the NEAR SCA 9901:
- grain diameter = 14.6 cm  (5.75 in)
- core diameter = 4.2 cm (1.65 in)
- number of segments = 5
- segment length = 29 cm (11.42 in)
- nozzle throat diameter = 3.4 till 3.8 cm due to erosion (1.34 - 1.50 in)

Greetings,
Tony


Antoon Vyverman
Middelweg 56
B-3001 LEUVEN
Tel: +32(0)16404800
fax:: +32(0)16406100


----- Original Message ----- 
From: <ss-main-request at sugarshot.org>
To: <ss-main at sugarshot.org>
Sent: Monday, January 23, 2006 8:57 AM
Subject: SS-Main Digest, Vol 6, Issue 21


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> Today's Topics:
>
>    1. Breaking News ! SStS BEM test fired today.... (Rich Nakka)
>    2. RE: Breaking News ! SStS BEM test fired today....
>       (craig strudwicke)
>    3. Battery requirement (rough cut) (craig strudwicke)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 22 Jan 2006 22:58:32 -0500
> From: Rich Nakka <richnakka at rogers.com>
> Subject: [SS-Main] Breaking News ! SStS BEM test fired today....
> To: Sugar Shot <ss-main at sugarshot.org>
> Message-ID: <43D45468.3000309 at rogers.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Greetings!
>
> The Ballistic Evaluation Motor (BEM) was static-test fired for the first
> time this afternoon. For those of you not familiar with the BEM, this
> was a ¼ scale version of our planned full size motor. The main
> difference, besides size, was the construction, being all-steel rather
> than composite. The primary objectives were to test the dual-phase
> concept, and to gather data on the performance of the KNSB propellant.
>
>   <>The first-phase motor fired spectacularly and burned for the planned
> 3 seconds. This was followed by the burning of the mid-bulkhead delay
> charge, which appeared to function exactly as expected. The second phase
> then ignited and also fired spectacularly. At approximately two seconds
> into the burn, however, the casing ruptured. Post-firing examination
> showed that the failure occurred at the welded EMT seam. <>
>
> Excellent data on thrust and chamber pressure were recorded. Preliminary
> examination of the data indicates nominal motor performance. The shape
> of the thrust curve was close to that predicted, and did not exhibit the
> dreadful "triangular" thrust profile typically seen in KNSB motor
> firings. This was a welcome sight...! <>
>
> The failure of the EMT tubing came as a surprise. Undoubtedly it was
> thermal related, as the casing had been hydro-tested earlier to 1.4x
> MEOP (=1500) psi. Failure occurred at just below MEOP. The casing had
> been designed to safely accommodate a casing temperature of over 1000 F
> (red hot), so (my) initial thoughts are a faulty seam weld. <>
>
> Overall, though, this test must be considered a great success. The
> dual-phase concept worked like a charm, and the motor and
> instrumentation performed (otherwise) as we'd hoped. <>
>
> A huge thank you to  Randy Dormans and Peter Current for all the work
> they put into the BEM project and conducting the test firing. Thanks as
> well to the other members of the Motor Development Team for all the
> effort put into the design & fabrication of the motor and
> instrumentation. We look forward to an even more successful second
> firing of the BEM. <>
>
> Photo of setup:
>
> http://sugarshot.org/downloads/prior_to_test.jpg
>
> Videos of BEM static test firing:
>
> http://sugarshot.org/downloads/bem_test_01_21_06_close.wmv
> http://sugarshot.org/downloads/bem_test_01_21_06_wide.wmv
>
> BEM technical drawing:
> http://sugarshot.org/downloads/bem_motor.pdf
>
> Richard
> =======
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> Message: 2
> Date: Mon, 23 Jan 2006 18:39:39 +1100
> From: "craig strudwicke" <cstrudwicke at optushome.com.au>
> Subject: RE: [SS-Main] Breaking News ! SStS BEM test fired today....
> To: "Sugar Shot" <ss-main at sugarshot.org>
> Message-ID:
> <NJEEJAOGEMKNPMLLEONAEEFNDLAA.cstrudwicke at optushome.com.au>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Awesome effort guys !  That's a significant bit of progress right there !
>
> CS
>
> PS: Last link is incorrect I suspect.
> -- 
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> Message: 3
> Date: Mon, 23 Jan 2006 19:00:35 +1100
> From: "craig strudwicke" <cstrudwicke at optushome.com.au>
> Subject: [SS-Main] Battery requirement (rough cut)
> To: "Sugar Shot" <ss-main at sugarshot.org>
> Message-ID:
> <NJEEJAOGEMKNPMLLEONAMEFNDLAA.cstrudwicke at optushome.com.au>
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