1. Antonio Crispin Chester Hawkins Huy Le

2. Problem:
A 25% scale model of an undersea vehicle which has a maximum speed of 16 m/s is to be tested in a wind tunnel with a pressure of 6 atm to determine the drag characteristics of the full-scale vehicle . The model is 3 m long. Find the air speed required to test the model and find the ratio of the model drag to the full scale drag.

3. For dynamic similarity, the Reynold’s number of the model and the real vehicle must agree:
Kinematic viscosities

4. The Test Condition At 50 F For a 25% scale: Lm = .25 Lv Assume
- a water temperature of 50 F
- an air temperature of 70 F
We find the viscosities and densities (or kinematic viscosities) using a reference table.
At 50 F

5. At 70F
Air speed

6. Equating dimensionless forces
Ratio of model drag to full scale drag
Since Lm=.25Lv , Am=(.25)2Av =.0625Av