I remember writing Fortran code to run the Barrowman equations on my Kaypro II. I couldn't believe how overstable all of my Estes rockets were. Started building from scratch in order to get stability down to 1-2 calibers.

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Let us create vessels and sails adapted to the heavenly ether, and there will be those who will not shrink from even that vast expanse. - Kepler to Galileo in 1610

NAR 86500
Level 2

Yes, apparently most commercial kits were (are) way, way overly stable.

I recall a latter 70s Model Rocketeer magazine article (NAR mag) by G. Harry Stine where he took several commercial kits and showed them built stock side by side with a version he did of each showing the amount of fin area needed to make it one caliber stable. The reduction in fin area on his redesigned versions were dramatic; really dramatic.

Earl

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Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

Kaypro II . . . A "Blast From The Past" !

"The Kaypro II has a 2.5 MHz Zilog Z80 microprocessor; 64 kB of RAM; two single-sided 191-kilobyte 5¼-inch floppy disk drives (named A: and B: ), and an 80-column, green monochrome, 9" CRT that was praised for its size and clarity (the Osborne 1 had a 5" display)."

Dave F.

Attached Thumbnails

 

__________________
"Failure Is Not An Option . . . Adapt & Overcome ! "

NAR # 26128 L2
TRIPOLI # 517 L2 ( inactive, at present )

Siblings named Gent and Merry; they were into watersports...


Bill

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It is well past time to Drill, Baby, Drill!

If your June, July, August and September was like this, you might just hate summer too...

Please unload your question before you ask it unless you have a concealed harry permit.

: countdown begin cr dup . 1- ?dup 0= until cr ." Launch!" cr ;

Give a man a rocket and he will fly for a day; teach him to build and he will spend the rest of his days sanding...

RockSim was first released in 1997.

https://www.apogeerockets.com/RockSim/Version_History


Bill

__________________
It is well past time to Drill, Baby, Drill!

If your June, July, August and September was like this, you might just hate summer too...

Please unload your question before you ask it unless you have a concealed harry permit.

: countdown begin cr dup . 1- ?dup 0= until cr ." Launch!" cr ;

Give a man a rocket and he will fly for a day; teach him to build and he will spend the rest of his days sanding...

Undoubtedly to account for the way some people are poor at following instructions.

At least the big companies like Estes did. Some designs from smaller companies were less conservative.

__________________
It is well past time to Drill, Baby, Drill!

If your June, July, August and September was like this, you might just hate summer too...

Please unload your question before you ask it unless you have a concealed harry permit.

: countdown begin cr dup . 1- ?dup 0= until cr ." Launch!" cr ;

Give a man a rocket and he will fly for a day; teach him to build and he will spend the rest of his days sanding...

in the beginning was Gary Crowell's VCP....https://sites.google.com/site/vcpro...tor/vcp-history copyright 1995

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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.

I've always wondered about this Estes Technical Report, TR-9 , "Designing Stable Rockets", by a William J. Taylor, III.

The CP calculations look really close to Jim Barrowman's original equations. The Masters thesis Barrowman Report came out in March 1967. This TR-9 in 1965. ??

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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.

There is no "Learning Curve" with those Manual Calculations . . .

Simply measure your rocket and enter the numbers in the proper location.

NASA didn't have "MoonSim" in the 1960's ( Slide Rules, Pencils, & Brains "ruled the day" ) !

Dave F.

__________________
"Failure Is Not An Option . . . Adapt & Overcome ! "

NAR # 26128 L2
TRIPOLI # 517 L2 ( inactive, at present )

Estes TR-9 ( 1965 )

Barrowman Report ( NARAM - 8 / August, 1966 )

Barrowman Master's Thesis ( March, 1967 )

LaBudde - "Barrowman Extended" ( 1999 ).

"What Barrowman Left Out" - Robert Galejs ( M.I.T. - Year ??? )

Dave F.

Attached Files

	EstesTR9.pdf (694.0 KB, 20 views)
	BARROWMAN REPORT.pdf (734.5 KB, 19 views)
	BARROWMAN - MASTERS THESIS.pdf (1.90 MB, 19 views)
	Labudde_1999_CP - BARROWMAN EXTENDED.pdf (286.4 KB, 21 views)
	WHAT BARROWMAN LEFT OUT - Robert Galejs.pdf (146.4 KB, 24 views)

__________________
"Failure Is Not An Option . . . Adapt & Overcome ! "

NAR # 26128 L2
TRIPOLI # 517 L2 ( inactive, at present )