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  #11  
Old 04-23-2021, 03:11 PM
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Dugway Dugway is offline
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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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  #12  
Old 04-23-2021, 04:13 PM
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Quote:
Originally Posted by Dugway
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.


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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  #13  
Old 04-23-2021, 04:25 PM
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Quote:
Originally Posted by Dugway
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.


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.
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  #14  
Old 04-24-2021, 03:24 AM
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Quote:
Originally Posted by ghrocketman
Does this Bruce Lee also have a sister named Ugh ?


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


Bill
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  #15  
Old 04-24-2021, 03:25 AM
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Quote:
Originally Posted by shockwaveriderz
this is what OpenRocket is for. or RockSim or RASAero 2



RockSim was first released in 1997.

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


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...
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  #16  
Old 04-24-2021, 03:28 AM
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Quote:
Originally Posted by Earl
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



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.
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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...
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  #17  
Old 04-24-2021, 01:32 PM
shockwaveriderz shockwaveriderz is offline
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Quote:
Originally Posted by Bill
RockSim was first released in 1997.

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


Bill


in the beginning was Gary Crowell's VCP....https://sites.google.com/site/vcpro...tor/vcp-history copyright 1995
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  #18  
Old 04-24-2021, 01:51 PM
shockwaveriderz shockwaveriderz is offline
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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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  #19  
Old 04-24-2021, 04:36 PM
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Quote:
Originally Posted by shockwaveriderz
this is what OpenRocket is for. or RockSim or RASAero 2


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.
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  #20  
Old 04-24-2021, 04:42 PM
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Quote:
Originally Posted by shockwaveriderz
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. ??



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
File Type: pdf EstesTR9.pdf (694.0 KB, 20 views)
File Type: pdf BARROWMAN REPORT.pdf (734.5 KB, 19 views)
File Type: pdf BARROWMAN - MASTERS THESIS.pdf (1.90 MB, 19 views)
File Type: pdf Labudde_1999_CP - BARROWMAN EXTENDED.pdf (286.4 KB, 22 views)
File Type: pdf WHAT BARROWMAN LEFT OUT - Robert Galejs.pdf (146.4 KB, 24 views)

Last edited by Ez2cDave : 04-24-2021 at 05:25 PM.
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