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The aims of testing are to develop the designs of:
a) the parachute
b) the protective structure, in order to minimise the impact to cargo inside the container.
The number of tests must be maximised within a limited budget. As tests involving real drops
from aircraft are costly, these must be kept to a minimum.

II Exchanging views on predictions and theories
4 a In pairs, answer the following questions.
1 What kinds of cargo is sometimes dropped from aircraft, and why?
2 What are the advantages and disadvantages of air-drops?

b Read the following predictions of how a container air-dropped with
parachutes might behave while falling, and on hitting the ground. Complete the predictions
by underlining the words you think are correct.
15 The longer the container is in the air, the more its horizontal speed will
decrease/increase.
16 Compared with a low-altitude drop, the vertical speed of a high-altitude drop will be
lower/higher.
17 In terms of damage to the container, a high vertical/horizontal impact speed is
potentially worse.
18 A very low-altitude drop will most likely cause the container to slide/roll along the
ground.

c ►9.2 Arnaud and Jenna, two engineers, are talking at the start of an airdrop research
project. Which predictions in Exercise 4b do they agree on, and which do they disagree on?
How do their ideas compare with yours?

Arnaud: So, theoretically, the horizontal speed will keep decreasing until the container hits the
ground. The higher the drop altitude, the lower the horizontal speed at touchdown.
Jenna: Sure.
Arnaud: But, obviously, the higher the altitude, the higher the vertical speed, up to a certain
point.
Jenna: Absolutely. So, assuming the drop altitude’s very low, the vertical speed won’t be all that
high on impact.
Arnaud: True.
Jenna: And in terms of protecting the cargo, surely a low vertical speed is the critical factor.
Arnaud: I’m not so sure it's the critical factor.
I’d say the horizontal speed's more problematic. Because, presumably, if the groundspeed’s

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