Jump to content

Close
--Click to Remove Ads--
Photo
* * * * * 1 votes

Understanding The Physics of Slingshots


  • Please log in to reply
85 replies to this topic

#81 aiping

aiping

    100 Post Club

  • Registered
  • 170 posts
  • LocationTaiwan

Posted 30 March 2017 - 04:05 AM

that's what I mean..

Attached Thumbnails

  • Punch .JPG


#82 aiping

aiping

    100 Post Club

  • Registered
  • 170 posts
  • LocationTaiwan

Posted 30 March 2017 - 04:08 AM

besides, that was my last 13 mm, I am struggling to find it in all the mess of my attic..., the ball on the magnet is 9.5 mm



#83 busySteve

busySteve

    100 Post Club

  • Registered
  • 246 posts
  • LocationBuford, GA

Posted 30 March 2017 - 05:25 PM

Current findings:

I kinda knew this but could not prove it until now... Below is a pic of two graphs, left is a pair of 1/2 inch x 10.5 TBG, and the other is a pair of 1 inch x 10.5 TBG. Both stretched to 50in total length:

458232a9852c6fd455f5f2bef9fd8d42.jpg

The retraction  curve is nearly identical. With the numbers in half proportions. When I run these values though the calculation the velocity is not double with the wider bands but the power is. It is almost exactly doubled:

FPS=276.322 / FPE=9.339
FPS=391.837 / FPE=18.779

This should lead us to predictable banding and a savings in rubber due to less trial and error cuts, once I write the banding Web page.


Edited by busySteve, 30 March 2017 - 05:32 PM.


#84 aiping

aiping

    100 Post Club

  • Registered
  • 170 posts
  • LocationTaiwan

Posted 30 March 2017 - 06:43 PM

Great prove! Will it be same for tapered bandsbands?

#85 busySteve

busySteve

    100 Post Club

  • Registered
  • 246 posts
  • LocationBuford, GA

Posted 30 March 2017 - 07:01 PM

Don't know yet

#86 busySteve

busySteve

    100 Post Club

  • Registered
  • 246 posts
  • LocationBuford, GA

Posted 03 April 2017 - 03:37 PM

Turns out I don't understand tapered bands. I did some testing and I can speculate but I can't express it in math... yet.

Here's the deal, I cut two band sets of TBG. 3/4 inch by 10.5 straight, and 1/2 inch to 1 inch tapered 10.5 long.

This equals the same surface area. See area images attached.


These had similar draw tension between them. The tapered set was actually a little lighter. After stretching then to a 50inch length (41 inch draw) I banded them on two hdpe Axiom Champs from Simple Shot OTT with BB kangaroo pouches. The straight band set clocked 190s FPS on the Chrony. The tapered set clocked 230s FPS. Each with 3/8 steel ammo.

I'd like to hear some theories of why this might be, if ya'll don't mind. I think weight offset is the biggest factor but there seems to be more.eb4bfb078dfb8536d73054a82067c0c9.jpg5e7c0fb6d420571bd3da2a6e63077316.jpg

Sent from my SM-G920T using Tapatalk




--Click to Remove Ads--