Go to Post "Heres a band aid to keep your blood off the robot." - littleelectron [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #31   Spotlight this post!  
Unread 11-01-2006, 20:56
Alan Anderson's Avatar
Alan Anderson Alan Anderson is offline
Software Architect
FRC #0045 (TechnoKats)
Team Role: Mentor
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Kokomo, Indiana
Posts: 9,113
Alan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond repute
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

Quote:
Originally Posted by Mirza95vx
Air resistance is not a factor unless you are going 75+ mph.
Aerodynamic drag is definitely a factor for a fluffy object like a Poof ball. It's not an extremely large factor, but it has a real and noticeable effect.
  #32   Spotlight this post!  
Unread 12-01-2006, 01:56
Tatsu Tatsu is offline
Audiophile and Physicist.
AKA: Tatsu Hashimoto
FRC #1072 (Harker Robotics Team)
Team Role: Leadership
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Woodside
Posts: 49
Tatsu will become famous soon enough
Send a message via AIM to Tatsu
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

Quote:
Originally Posted by Mirza95vx
Air resistance is not a factor unless you are going 75+ mph. So you dont have to account air resistance into the equation.
You're kidding right? You lose around 4 meters to air resistance fireing 45 degrees from 0 -> 0 at 12 m/s. This is fairly nontrivial. Initial deceleration is easy to calculate

F= 1/2 Cd * rho * A * v^2

for a poof ball, thats's about

F= 7.52e-3 * v^2

F= 1.08 Newtons.. that may seem insignificant.. but the poof ball is light..

F=ma=1.08 , so taking m = .18 kg we get a = 6.016 m/s^2 deceleration..

yes, that's about 2/3rds g, that's nontrivial.
  #33   Spotlight this post!  
Unread 12-01-2006, 07:59
KenWittlief KenWittlief is offline
.
no team
Team Role: Engineer
 
Join Date: Mar 2003
Location: Rochester, NY
Posts: 4,213
KenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond repute
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

Quote:
Originally Posted by Mirza95vx
Air resistance is not a factor unless you are going 75+ mph. So you dont have to account air resistance into the equation.
You drive a Honda Scion, dont you?

(Aerodynamics ?! we dont need no stinking aerodynamics! :^)
  #34   Spotlight this post!  
Unread 12-01-2006, 09:07
galewind's Avatar
galewind galewind is offline
... more like a temperate breeze
AKA: Chris Gregory
FRC #1089 (Team Mercury)
Team Role: Teacher
 
Join Date: Jan 2003
Rookie Year: 2003
Location: Hightstown, NJ
Posts: 410
galewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond reputegalewind has a reputation beyond repute
Send a message via AIM to galewind
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

ugliest...vehicle...ever...
__________________
Chris G
Advisor, Team Mercury (1089), Hightstown High School
  #35   Spotlight this post!  
Unread 12-01-2006, 13:51
Tatsu Tatsu is offline
Audiophile and Physicist.
AKA: Tatsu Hashimoto
FRC #1072 (Harker Robotics Team)
Team Role: Leadership
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Woodside
Posts: 49
Tatsu will become famous soon enough
Send a message via AIM to Tatsu
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

Btw, the 2-dimentional version of calculation is done.

check the programming section for my mathematica notebook its called something like traj.zip.. gimmie a day and I'll also upload the raw data in CSV form.
  #36   Spotlight this post!  
Unread 12-01-2006, 19:49
racsan12345 racsan12345 is offline
Registered User
FRC #1351
 
Join Date: Jan 2006
Location: San Jose
Posts: 3
racsan12345 is an unknown quantity at this point
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

For launching 4.5 feet to 8.5 feet:

Please input the initial velocity in meters per second: 12.8
Please input the coefficient of drag (0.07 - 0.5): 0.416
The uber best range is 14.7775 meters at an uber angle of 47 degrees.


C++ Code:
#include <iostream.h>
#include <math.h>

int main()
{
// float i = cos(x); x is in radians
// float i = atan(x); i is in radians arctangent

float x;
float y;
float v_initial = 12.8;
float v_x;
float v_y;
float initial_angle;
float theta;
float drag;
float area = pow((3.5 * 2.54 / 100), 2) * 3.14159;
float mass = .206; //kilograms
float C_D; //Coefficient of Drag
float a_x;
float a_y;
float increment = .01; //Incrementing time
float best_range;
float rad_conv = 2.0 * 3.14159 / 360.0;
float uber_best_range = 0;
float uber_angle = 0;

cout << "This program will calculate the maximum range and best angle to launch a 7 inch diameter poof ball." << endl << endl;
cout << "Please input the initial velocity in meters per second: ";
cin >> v_initial;

cout << "Please input the coefficient of drag (0.07 - 0.5): ";
cin >> C_D;

for(initial_angle = 10; initial_angle <= 80; initial_angle++)
{
x = 0;
y = 0;
v_x = v_initial * cos(initial_angle * rad_conv);
v_y = v_initial * sin(initial_angle* rad_conv);
best_range = 0;

do
{
theta = atan(v_y/v_x);
drag = .5 * C_D * area * sqrt(pow(v_x, 2) + pow(v_y, 2));
a_x = drag / mass * cos(theta);
a_y = drag / mass * sin(theta) + 9.8;

v_x = v_x - a_x * increment;
v_y = v_y - a_y * increment;

x = x + v_x * increment;
y = y + v_y * increment;

if(y > 1.3 && v_y < 0)
best_range = x;

}while(y >= 0);

cout << "At " << initial_angle << " degrees, the best range is " << best_range << " meters." << endl << endl;

if(best_range > uber_best_range)
{
uber_best_range = best_range;
uber_angle = initial_angle;
}

}

cout << "The uber best range is " << uber_best_range << " meters at an uber angle of " << uber_angle << " degrees.";

return 0;
}

--Ownage
  #37   Spotlight this post!  
Unread 12-01-2006, 20:06
Tatsu Tatsu is offline
Audiophile and Physicist.
AKA: Tatsu Hashimoto
FRC #1072 (Harker Robotics Team)
Team Role: Leadership
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Woodside
Posts: 49
Tatsu will become famous soon enough
Send a message via AIM to Tatsu
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

nice, nearly identical code, different language.

(btw, you might want to run it for <1 degree increments)
  #38   Spotlight this post!  
Unread 12-01-2006, 20:47
Rick TYler Rick TYler is offline
A VEX GUy WIth A STicky SHift KEy
VRC #0010 (Exothermic Robotics)
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Redmond, Washington
Posts: 2,000
Rick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond reputeRick TYler has a reputation beyond repute
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

Quote:
Originally Posted by KenWittlief
You drive a Honda Scion, dont you?
Have I been trolled?

The Scion Xb is Toyota's ugly cube. Honda's ugly cube is the Element.
__________________
Exothermic Robotics Club, Venturing Crew 2036
VRC 10A, 10B, 10D, 10Q, 10V, 10X, 10Z, and 575
  #39   Spotlight this post!  
Unread 14-01-2006, 00:15
Nuttyman54's Avatar
Nuttyman54 Nuttyman54 is offline
Mentor, Tactician
AKA: Evan "Numbers" Morrison
FRC #5803 (Apex Robotics) and FRC #0971 (Spartan Robotics)
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Seattle, WA/Mountain View, CA
Posts: 2,144
Nuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond reputeNuttyman54 has a reputation beyond repute
Send a message via AIM to Nuttyman54
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

971 got .41 ish as our Coefficient of drag (using wind-tunnel testing). Can we assume this is verified. Also, I don't know if this has been explained, but the "rho" in the drag equation is air density, generally around 1.2 kg/m^3.
__________________
  #40   Spotlight this post!  
Unread 14-01-2006, 19:04
Tatsu Tatsu is offline
Audiophile and Physicist.
AKA: Tatsu Hashimoto
FRC #1072 (Harker Robotics Team)
Team Role: Leadership
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Woodside
Posts: 49
Tatsu will become famous soon enough
Send a message via AIM to Tatsu
Re: Nerf ball starting at 12m/s 45 degree angle ending at 8ft 6in w/ air resistance

.41 matches prediction. prediction is .416 with flow of 12m/s
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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 00:51.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi