Why study rockets

1
Why study rockets?

• One could argue that the greatest form of human
  communication will be with extra-terrestrial life
  forms.
• Through space exploration, this form of
  communication may become a reality.

2
What every good rocket scientist should know

• Center of Mass
• Center of Pressure
• Rocket Stability

3
Center of Mass

• The spot on a rocket that is balanced

4
Measuring the Center of Mass

• 1. Using a ruler or pencil, find where your
  rocket is balanced
• 2. Mark the COM on your rocket

5
Center of Pressure

• The spot on a rocket where the surface area above
  and below is the same

6
Measuring the Center of Pressure

• Trace your rocket onto a piece of cardboard
• Cut out the flat picture of your rocket
• Find and mark the COM of the cardboard
• The COM of the cardboard cutout is the same as
  the COP of the rocket
• Place the rocket next to the cardboard and mark
  the COP on your rocket

7
Whats up with COM and COP?

• Rockets rotate around the Center of Mass
• Force from the air (air resistance) is exerted at
  the Center of Pressure

8
When a rocket turns off path
9
When a rocket turns off path
10
The COM should be near the nose the COP should
be near the tail

• That was the point of the last two slides!

11
Why the COM should be far from the COP
1 because you are exerting a force farther from
the pivot point
12
Why the COM should be far from the COP

• Long handled wrenches

B because you are pushing farther from the pivot
point (the red hex nut). This is why a long
handled wrench can turn a really tight hex nut.
13
Another example

• Fat handled screwdrivers

A because you are exerting the force farther from
the middle (the pivot point). So fat handled
screwdrivers are good for screws that are hard to
loosen.
14
Achieving Stability

• Distance between COM and COP should be at least
  one diameter

Add weight here to change the COM
If the COP is far from the COM, the same force
will twist the rocket back on line better.
15
Brief History of the Space Program

• In 1957, the Soviet Union launched the first man
  made satellite (Sputnik) into orbit around the
  Earth.
• In 1961, the Soviet Union put the first man in
  space (Yury Gagarin).
• Gagarin made one orbit of the Earth in 1 hour, 29
  minutes, reaching a max. altitude of 187 miles.
• Food for thought What was Yury thinking about
  while on the launch pad?

16
Brief History of the Space Program

• The Soviets winning the race to space triggered
  panic in the U.S., as people worried that the
  Soviet Union held military advantage over the
  U.S.
• John F. Kennedy, president of the United States,
  made putting a man on the moon a national
  priority.

17
John F. Kennedy (1917 1963)35th president of
the United States
We choose to go to the moon in this decade, and
do the other things, not because they are easy,
but because they are hard. Because that goal
will serve to organize and measure the best of
our energies and skills. Because that challenge
is one that were willing to accept. One we are
unwilling to postpone. And one we intend to win,
and the others too.