# Homework Help: How to replicate a realistic Reynolds number for an airfoil

1. Dec 1, 2017

### MattH150197

1. The problem statement, all variables and given/known data
Hi im doing a project of designing and testing a wing in a wind tunnel, the wing is based a cessna 172 skyhawk wing and im trying to determine what chord length it should be to try and replicate similar reynolds numbers that a cessna 172 wing would experience in real life.

2. Relevant equations

3. The attempt at a solution
I found that at 8000 ft the reynolds number ranges from 2 - 5.4 million Re for the aircraft, i found temp and pressure in wind tunnel to get density 1.24. I then put 5.4 million = 1.24*40(max wind tunnel speed) * L / 1.81x10^-5 (dyn viscosity) and worked out for L but i got a value of 1.8 m which is too big for my average chord length. Can anyone see that im doing something wrong or can suggest how i can produce more similar reynolds numbers for the airfoil. Thanks

2. Dec 6, 2017

### PF_Help_Bot

Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.