7/30/2019 USLI Presentation - Task 7

1/7

Wind Tunnel Testing Planfor Dual Grid Fins

Eric CaoUSLI / 481L

11/19/12

1Eric Cao ARO 481L/ USLI

7/30/2019 USLI Presentation - Task 7

2/7

Overview

2

New grid fin design View of the grid fins, mount, and baseplate on the

sting Wind tunnel flight plan (various pitch angles, yaw

angles, and velocities) Procedures before/during/after flight plan

Wind tunnel data reduction and correction How data will be used to improve Project

PLATYPUS

Eric Cao ARO 481L/ USLI

7/30/2019 USLI Presentation - Task 7

3/7

New Dual Grid Fin Mount on Sting

3Eric Cao ARO 481L/ USLI

Four bolts will secure the adapter to the back face of the baseplate

The adapter has a 5/8 threaded female hole which will allowit to be secured to the sting

M sting

Back view

7/30/2019 USLI Presentation - Task 7

4/7

Wind Tunnel Testing Plan

4

Two grid fins will be mounted on the baseplate, which will beattached to the adapter and the wind tunnels sting

Velocity will slowly be increased from 0 fps to 300 fps at apitch angle of 20 and a yaw angle of 7 (most deflectedposition)

Any sign of unexpected vibrations or malfunctions fromthe grid fin, velocity will be dialed down to 0 fps

Corrections will be made to have no malfunctions at worst

case (300 fps, 20 pitch, 7 yaw) Once verified that the worst case has no malfunctions, the

flight plan will be applied

Eric Cao ARO 481L/ USLI

7/30/2019 USLI Presentation - Task 7

5/7

Wind Tunnel Testing Plan (cont.)

5

Wind tunnel will be programmed to run through the plantwice, once with the grid fins, once without grid fins

Velocity of 0 fps to 300 fps, increments of 20 fps Pitch angles of -5 to +20 , increments of 1 Yaw angles of -2 to +7 , increments of 1

With grid fins : Velocity at 0 fps, pitch held constant at-5 , then it yaws from -2 to +7 . Pitch changes to -4 ,

then it yaws from -2 to +7 Pitch changes to 20 ,then it yaws from -2 to +7 . Velocity changes to 20 fps,40 fps, 60 fps, 300 fps

Without grid fins : Procedure above repeated

Eric Cao ARO 481L/ USLI

7/30/2019 USLI Presentation - Task 7

6/7

Summary

6

A total of 8,320 data points will be recorded [16

26

10

2(different velocities, pitch/yaw angles, with/without grid fins)]

Data Reduction Each force found at each data point testedwithout grid fins will be subtracted from the same forcesfound at the corresponding data point tested with grid fins,which will give the forces produced by two grid fins at acertain orientation (reduces from 8,320 to 4,160 data points)

Data Correction Each of the 4,610 data points will becorrected for the right velocities using the correspondingcorrected air speed factor provided by Cal Poly PomonasAerospace Department

Eric Cao ARO 481L/ USLI

7/30/2019 USLI Presentation - Task 7

7/7

Summary (cont.)

7

4,160 data points will be plotted on graphs with axise.g. (Normal, Side, or Axial Force vs. Pitch or Yaw Angle)

Normal/side forces vs. pitch/yaw angles graphs will be used tocalculate the new rockets theoretical center of pressurelocation through our customized computer code

Axial force vs. pitch/yaw angles graphs will be used to calculatedrag and when to actuate the grid fins to induce more drag to

be able to reach exactly one mile

Eric Cao ARO 481L/ USLI