Lab2v3prelabweek2
.pdf
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School
University of Michigan *
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Course
100
Subject
Aerospace Engineering
Date
Apr 3, 2024
Type
Pages
2
Uploaded by AdmiralPigeon2129 on coursehero.com
11
Lab 2 pre-lab
Name:__________________________________
Week 2 (30 pts)
Section:
Mon
Tue
Fri AM
Fri PM
The Lab 2 pre-lab is due in two parts. Problems 1 thru 3 are due prior to the first week
of lab. Problems 4 thru 6 are due prior to the second week of lab.
4. (10 pts tech) The sting is a circular wooden dowel 12.4 mm in diameter and 40.5
cm long, of which 21.3 cm extends below the ceiling of the wind tunnel.
a. (1 pt) Which object number in Table 1 best describes the sting?
b. (9 pts) How much drag would you expect to be from just the sting in a 13.3 m/s
wind?
5. (10 pts tech) A drag article-under-test facing into the wind produces a drag
measurement of 3.973 N in a 15.0 m/s wind. The drag article has a circular projected
area of 16.3 cm diameter, but isn’t one of the canonical shapes in Table 1. Your
estimate of the drag due to the sting (see previous problem for an example of how to
calculate this) is 0.513 N. Assuming you can add the drag from the sting to the drag
from AUT to get the total drag measured by the wind tunnel data acquisition system,
what is the coefficient of drag of this drag AUT?
12
Team “Torque” tested the following object in
the wind tunnel, which was an Article Under
Test (AUT) made from two plastic bottles
strapped onto a sting, as shown in Fig. 3. The
bottles are 6.35 cm in diameter, with the mouth
of one facing into the wind and the mouth of the
other facing downwind. The drag from the sting
is negligible, and from previous measurements
(see previous problem for an example of how to
do this), the coefficient of drag of the bottle with
the mouth facing upwind is
C
D1
=1.29 and the
coefficient of drag for the bottle with the mouth
facing downwind is
C
D2
=0.79. Some other
relevant measurements are the dimensions
below.
x
2
= 18.8 cm
x
3
= 37.1 cm
y
1
=
y
2
= 12.4 cm
Figure 3.
Free body diagram of forces on a torque AUT made from two plastic
bottles in the wind tunnel.
6. (10 pts tech) An article-under-test is mounted in the wind tunnel as depicted in Fig.
3.
a. (9 pts) In a 14.3 m/s wind, what would you expect for the magnitude of the torque
on the sting due to the bottles?
b. (1 pt) Which direction is the (positive) torque from the AUT on the sting, when viewed
from above?
CW or CCW?
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