Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > Building Techniques
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 04-22-2021, 11:39 PM
Ez2cDave's Avatar
Ez2cDave Ez2cDave is offline
Banned
 
Join Date: Mar 2005
Location: Raleigh, NC Area
Posts: 1,743
Default MANUAL Calculation Of CENTER OF PRESSURE . . .

Back in the day, circa 1995, a Tripoli rocketeer, named Bruce Lee, developed a simplified method to manually calculate Center of Pressure.

His 10-year old son was able to do the computations with ease.

Dave F.
Attached Thumbnails
Click image for larger version

Name:  1.jpg
Views: 70
Size:  1.28 MB  Click image for larger version

Name:  2.jpg
Views: 80
Size:  659.2 KB  Click image for larger version

Name:  3.jpg
Views: 76
Size:  691.4 KB  Click image for larger version

Name:  4.jpg
Views: 59
Size:  772.4 KB  Click image for larger version

Name:  5.jpg
Views: 68
Size:  1.19 MB  Click image for larger version

Name:  6.jpg
Views: 60
Size:  1.43 MB  
Reply With Quote
  #2  
Old 04-23-2021, 05:20 AM
mojo1986's Avatar
mojo1986 mojo1986 is offline
Old Canuck Modeller
 
Join Date: Mar 2005
Location: Kingston, CANADA
Posts: 2,162
Default

Smart 10-year old!
Reply With Quote
  #3  
Old 04-23-2021, 07:30 AM
barone's Avatar
barone barone is offline
Master Modeler
 
Join Date: Apr 2005
Location: Bartlett, TN
Posts: 3,352
Send a message via Yahoo to barone
Default

I still use the cardboard cut-out method.
__________________
Don
NAR 53455
"Carpe Diem"
Reply With Quote
  #4  
Old 04-23-2021, 09:17 AM
Ez2cDave's Avatar
Ez2cDave Ez2cDave is offline
Banned
 
Join Date: Mar 2005
Location: Raleigh, NC Area
Posts: 1,743
Default

Quote:
Originally Posted by mojo1986
Smart 10-year old!


DEFINITELY, a LOT SMARTER than what today's "Schools" are turning out !

Dave F.
Reply With Quote
  #5  
Old 04-23-2021, 09:21 AM
Ez2cDave's Avatar
Ez2cDave Ez2cDave is offline
Banned
 
Join Date: Mar 2005
Location: Raleigh, NC Area
Posts: 1,743
Default

Quote:
Originally Posted by barone
I still use the cardboard cut-out method.


Nothing wrong with that, as it is very "conservative" about CP location.

It gives a "safe" CP location ( FORWARD of its ACTUAL location ) . . .

The "downside" to the Cardboard Cutout method is that it "calls for" extra Nose Weight, which reduces performance and creates an "overstable" situation.

Dave F.

Last edited by Ez2cDave : 04-24-2021 at 04:31 PM.
Reply With Quote
  #6  
Old 04-23-2021, 09:43 AM
ghrocketman's Avatar
ghrocketman ghrocketman is offline
President, MAYHEM AGITATORS, Inc.
 
Join Date: Jul 2005
Location: Nunya Bizznuss, Michigan
Posts: 13,587
Default

Does this Bruce Lee also have a sister named Ugh ?

I don't ever bother with CP calculation. I just fly it. If it flies ok, the CP/CG relationship is ok too.
__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, AGITATION, CHAOS, TURMOIL, FIASCOS, AGGRAVATION, INSTIGATION, NUISANCE-ACTION, and HAVOC !
Reply With Quote
  #7  
Old 04-23-2021, 10:32 AM
Ez2cDave's Avatar
Ez2cDave Ez2cDave is offline
Banned
 
Join Date: Mar 2005
Location: Raleigh, NC Area
Posts: 1,743
Default

Quote:
Originally Posted by ghrocketman
I don't ever bother with CP calculation. I just fly it. If it flies ok, the CP/CG relationship is ok too.


That gave me a "flashback" to my youth . . . Home-made fireworks, labelled with a felt-tip marker "Light Fuse & Run Like Hell" . . . LOL !

Dave F.
Reply With Quote
  #8  
Old 04-23-2021, 10:57 AM
tbzep's Avatar
tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
Posts: 11,634
Default

Quote:
Originally Posted by ghrocketman
If it flies ok, the CP/CG relationship is ok too.

Their relationship may seem ok, but they still need a chaperone.
__________________
I love sanding.
Reply With Quote
  #9  
Old 04-23-2021, 11:17 AM
shockwaveriderz shockwaveriderz is offline
rocket dinosaur
 
Join Date: Mar 2005
Location: My Old Kentucky Home
Posts: 1,184
Smile

this is what OpenRocket is for. or RockSim or RASAero 2
__________________
"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.
Reply With Quote
  #10  
Old 04-23-2021, 11:39 AM
ghrocketman's Avatar
ghrocketman ghrocketman is offline
President, MAYHEM AGITATORS, Inc.
 
Join Date: Jul 2005
Location: Nunya Bizznuss, Michigan
Posts: 13,587
Default

Chaperone nuthin'
We dun't neeed no steeenkingg chaperone!
__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, AGITATION, CHAOS, TURMOIL, FIASCOS, AGGRAVATION, INSTIGATION, NUISANCE-ACTION, and HAVOC !
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 09:20 AM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2024