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(41C) … Grain Misalignment …
05-13-2019, 10:27 PM
Post: #1
(41C) … Grain Misalignment …
An extract from A Model for Grain Misalignment in Cylindrical Port Motors, US Army Missile Laboratory (Propulsion Directorate), TECHNICAL REPORT RK-84-4, APR 1984

ABSTRACT
This report presents a mathematical model of the geometry of the propellant grain of a cylindrical port motor cast with a misaligned mandrel. Also presented is an HP-41C calculator program which incorporates this model, and an example demonstrating the application of the misaligned motor geometry.

APPENDIX A
HP-41C PROGRAM

The mathematical model presented in this report has been incorporated into a program for an HP-41C calculator. This appendix is intended to provide all the information required to install and operate this program. This program, when installed on an HP-41 calculator system, will prove to be a useful analysis tool. The program as presented will provide the user with a convenient and accurate method for evaluating the geometry of misaligned cylindrical port motors. The following provides complete operating instructions, a set of sample problems, and a listing of the program. Also provided is all the required storage register and calculator status information needed to implement the program … Table A-1 provides a step by step key sequence required to operate this program.


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05-16-2019, 09:08 AM
Post: #2
RE: (41C) … Grain Misalignment …
(05-13-2019 10:27 PM)SlideRule Wrote:  An extract from A Model for Grain Misalignment in Cylindrical Port Motors, US Army Missile Laboratory (Propulsion Directorate), TECHNICAL REPORT RK-84-4, APR 1984

very nice one, thanks again for sharing your findings.
I don't suppose there's be a way to figure out program step 683 ?
unfortunately it's not shown in the copy...

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05-16-2019, 11:37 AM (This post was last modified: 05-16-2019 02:58 PM by SlideRule.)
Post: #3
RE: (41C) … Grain Misalignment …
Thanks for the review; good to know the post(s) have readership. My cursory perusal of the listing indicates the program steps most likely reference the variable τ₁ in equation 22. If so, the most likely candidate is the division operator (/). Can anyone confirm?

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05-16-2019, 04:27 PM
Post: #4
RE: (41C) … Grain Misalignment …
(05-16-2019 11:37 AM)SlideRule Wrote:  Thanks for the review; good to know the post(s) have readership. My cursory perusal of the listing indicates the program steps most likely reference the variable τ₁ in equation 22. If so, the most likely candidate is the division operator (/). Can anyone confirm?

Sounds sensible, I guess the definitive proof will require keying the program and running the examples... give me a few days, it's a nice subject that deserves resurrection.

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05-16-2019, 10:21 PM
Post: #5
RE: (41C) … Grain Misalignment …
(05-16-2019 04:27 PM)Ángel Martin Wrote:  Sounds sensible, I guess the definitive proof will require keying the program and running the examples... give me a few days, it's a nice subject that deserves resurrection.

And just exactly what kind of rocket motors are you making over there...

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05-17-2019, 01:56 AM
Post: #6
RE: (41C) … Grain Misalignment …
(05-16-2019 10:21 PM)rprosperi Wrote:  … what kind of rocket motors are you making ...

The emergency 'pilot/navigator' egress system for the F-111E & EF-111A was a 'grain propellant' based rocket motor; my weapons systems at RAF Upper Heyford (OXON) UK; but that's another story …

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05-18-2019, 02:04 PM
Post: #7
RE: (41C) … Grain Misalignment …
See attached the FOCAL code and the RAW file - who want's to do the honors?


Attached File(s)
.zip  OFCNTR.zip (Size: 5.25 KB / Downloads: 4)

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05-18-2019, 02:33 PM
Post: #8
RE: (41C) … Grain Misalignment …
(05-17-2019 01:56 AM)SlideRule Wrote:  The emergency 'pilot/navigator' egress system for the F-111E & EF-111A was a 'grain propellant' based rocket motor; my weapons systems at RAF Upper Heyford (OXON) UK; but that's another story …

I would not have guessed that kind of propellent for that. Must have been good sized to eject the entire cabin/escape module.

Awesome airplane - IMHO it never got/gets the respect it deserves. I suppose because so much of it's use was quiet, but still - amazing airplane and still nothing like it in the inventory today.

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05-18-2019, 05:52 PM
Post: #9
RE: (41C) … Grain Misalignment …
For those interested, a reasonable description / illustration of the F-111 Crew Module Escape and Survival Systems w/ detailed description & illustration {fig. 4} of the 'rocket motor' component of the crew capsule. Lots of flexible linear shape charges, pyrotechnic guillotines etc associated with separating the crew capsule from the air-frame, a very capable airframe, ahead of its' time (BOAC Lightning?): another blast from the past.

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05-18-2019, 07:32 PM
Post: #10
RE: (41C) … Grain Misalignment …
(05-18-2019 05:52 PM)SlideRule Wrote:  For those interested, a reasonable description / illustration of the F-111 Crew Module Escape and Survival Systems w/ detailed description & illustration {fig. 4} of the 'rocket motor' component of the crew capsule. Lots of flexible linear shape charges, pyrotechnic guillotines etc associated with separating the crew capsule from the air-frame, a very capable airframe, ahead of its' time (BOAC Lightning?): another blast from the past.

Excellent resource, thanks for sharing this!

"The rocket motor lower nozzle provides 27,000 pounds of thrust..." serious thrust for a grain propellant motor! Would love to have witnessed one of the test firings (on the ground) when developing this. Solid fuel like this kept it pretty much maintenance-free (well, low-maintenance) but with all the steps and technology required in the launch sequence, it's a wonder it worked, but I don't recall ever hearing of problems when they were needed (except for having to depart the airframe, I guess that has to be considered a problem...).

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08-30-2019, 05:16 AM
Post: #11
RE: (41C) … Grain Misalignment …
Now available in the [NASA] module from the CL Library.

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