# SCI-Fair help desperately needed

1. Oct 8, 2007

### jgb768

Ok so im doing an ambitious sciencefair that i could use so help getting my bearings on...

this is the abstract i found (done back in the 80's) and i need some help understanding parts of it

PURPOSE: To determine how different types of wind shear affect wing performance in flight and air flow around a wing. Performance means (a) lift or lift factor (Cl) and (b) wing stability. Until Recently, wind shear has not been well defined in fluid mechanics. Research in this area has been initiated because of recent airline crashes.
EXPERIMENTAL METHODS: A wind tunnel was constructed with a test chamber designed for this purpose. The wing is attached to a force transducer made with four strain gauges. The strain gauges’ output voltage was recorded with an oscilloscope (to measure wing stability). Once the transducer was calibrated, the following equation was used to compute lift coefficient: Cl = 2L/psVV, where L = Lift in dynes, p = density of air in g/ cm^3, s = wing’s area in cm^2, and V = wind velocity in cm/sec and refers to the main stream of air.

the part that is confusing me is the "The wing is attached to a force transducer made with four strain gauges. The strain gauges’ output voltage was recorded with an oscilloscope (to measure wing stability)."

how am i going to set up the wing in the windtunnel?????

I have done some research on oscilloscopes, forse transducers, and strain gauges and keep coming up empty handed.(no experience with this equiptment lol)

I get the equation and how to make the windtunnel as to allow for windshear as a variable... a push in the right direction would be great! thx

2. Oct 9, 2007

### jgb768

Also i am unfamiliar with airfoil types. what low speed airfoil would you recommend for this experiment?

cant believe i havent gotten any posts yet : (

3. Oct 10, 2007

### TVP45

I suspect you're in way over your head. Do you have a wind tunnel? What size? Is the flow laminar and controllable? How will you measure air velocities?

4. Oct 10, 2007

### jgb768

yea i figured that out today i am gonna test lift and drag vs the angle of attack and use a wing that already has benchmark data on it so i can compare it and fine tune my readings to get more accurated data

but i will still need the following equiptment

• Wind Tunnel
• Atlantis Data Acquisition Software
• Vishay Machine
• Calibration rod and weight
• Pitot Tube
• Test Specimen
from what i found at

http://www.columbia.edu/cu/mechanical/modi/kevin/windtunnel.html

but advice and pointers would be a huge encouragement to me so thanks for the comments/ ideas

5. Oct 10, 2007

### jgb768

the flow has to be laminar or my results would be inconsistant and un replicable, not to mention completely wrong hahaha... i will devise some stabalizing grid to make the flow less turbulant.

and as far as recording the wind velocities...i believe the "Pitot Tube" will do that in "height of oil" which im sure can be converted into m/s.

OH YEA totally forgot...... what should i use to make the windtunnel out of.... not the test section but everything else...like the settling chamber, the contraction cone and the diffuser? i was thinking would but would it be smooth enough??????

6. Oct 11, 2007

### TVP45

Are you by chance a student in an aerospace department (or at least good friends with one)?

7. Oct 11, 2007

### J77

And if you're not a student, I'd be looking to get along to your local university and finding a wind tunnel -- then explain to them what you want to use it for, then beg or bribe them for a go...

With that list of wants, this "science fair" project sounds way too demanding!

Have you had any experience running a wind tunnel?

8. Oct 11, 2007

### jgb768

no im afraid not, Im a senior in highschool, i plan to go to a local university, then transfer to Louisiana Tech, with hopes of attending graduate school at Texas A&M. My dad is a professor at a local state college, and is friends with the head of the physics dept. their, the guy is nationally renowned, and has built his own mini-sub, airplane(i think) and numerous large robotic vehicles lol. But i dont think they have a wind tunnel. :/

i have been working on changing up the project to make it more "do-able", but it is extremely difficult to come up with a project in this field that is challenging and impressive, that isnt elementry.
Any ideas for a challenging project that would atleast get me past regionals?

9. Oct 14, 2007

### jgb768

any project is good at this point, my goal from this project is to get me familiar with aerodynamics, and to be as challenging as possible. : ) i've always wanted to go to state too, b/c my projects have always betrayed my potential, and i really want one that i can honestly be proud of : ) but like i said... its soooooooooooo hard to come up with a do-able project in Aerodynamics : (

10. Oct 15, 2007

### Staff: Mentor

How about making a car-based wind tunnel? You'll need to do a good job with the diffuser, to get the flow flatter, depending on how far away/above the car you can mount the tunnel. You could make a pretty good 1-foot diameter tunnel, with wind speeds up to 65mph or so at the entry to the tunnel....

11. Oct 15, 2007

### jgb768

that might work, great idea... but if the equiptment is being loaned to me, then wouldnt it be risky to chance that it could fall off the trailer? and i am in louisiana, the roads here are sooooooooooooo horrible the bumpy-ness would definitely affect the measurments of the load cells to a point at which the data would be useless and un-replicable.

This project is looking more and more complicated each day, but it doesnt seem it should be. I can loan the equiptment from my school and the local college, and my grandfather runs an Airconditioning shop so getting a really good fan wouldnt be too hard. Is it really that challenging to make a wind tunnel? Im so new to this so the more Information you can tell me the better i will understand where u are coming from. Ex. why you say what u said, and what (should/should not) be done instead.