nomopbo
Well-Known Member
- Joined
- Jan 13, 2004
- Messages
- 526
- Reaction score
- 0
IT'S ROCKET SCIENCE
By Christian Toto
THE WASHINGTON TIMES
-----------------------------------------------------------
Flying model rockets may seem like child's play, but tell that to thousands of
science teachers nationwide who lean heavily on the cardboard creations.
In May, more than 500 middle and high school students -- whittled down from
nearly 10,000 contestants -- gathered in The Plains, Va., for the third annual
Team America Rocketry Challenge.
Teachers nationwide incorporated those efforts into their own plans, letting
the rockets' razzle-dazzle sell students on the physics of flight.
Trip Barber, vice president of the National Association of Rocketry, says
the basic physics lifting model rockets into the sky is identical to the forces
applied to genuine rockets.
A rocket kit straight out of the pack might fly to heights around 1,500
feet, says Mr. Barber, whose nonprofit group promotes the educational aspects of
the hobby.
Some rockets can fly much higher, particularly models created by more
skilled rocket enthusiasts.
After 1,500 feet, though, "you can't see it anymore," he says.
The average model rocket weighs less than a pound, thanks to its balsa-wood
fins, cardboard tubing and light plastic nose cone. The rockets fly straight
skyward, in part because of the fins, which are placed strategically on the main
tube and stabilize the flight, much like the feathers that keep an arrow's path
true.
Mary Roberts, technical services manager with Estes Rockets, says model
rocketry is a legally defined term. A rocket must weigh no more than 16 ounces
and contain no more than 4 ounces of propellant, Ms. Roberts says. Rocketeers
can fly models with engines less than or equal to those figures, or they can fly
multistage rockets whose combined thrusting material doesn't outweigh those
standards.
Should a model rocket overstep those bounds, the flier must notify the
Federal Aviation Administration for permission to fly the rocket, she says.
Ms. Roberts says even though her company's models use black powder solid,
not liquid propellant, they still slice through the atmosphere just like the
National Aeronautics and Space Administration's rockets.
The engines themselves are categorized by a letter system in which the total
impulse the craft provides doubles with every letter change. A "B" engine
contains twice the impulse power of an "A" engine, for example, says Ms.
Roberts, whose company has been making model rockets since 1958.
Model rockets start at less than $10, with engines running roughly the same
for a pack of three.
An "A" engine produces up to 2 Newton-seconds of total impulse, she says, a
measurement unit used for rocket speeds that analyzes how many pounds of force
are exerted for one second.
Alexandria resident John Hochheimer, a member of the Northern Virginia
Association of Rocketry, says a garden-variety model rocket can be improved by
using sturdy carbon fiber tubing for the rocket's main body. Most fall back on
the standard balsa and plastic constructs, says Mr. Hochheimer, whose group has
about 130 model-rocket enthusiasts.
Whether the rocket in question took weeks to build or just a few hours, the
rocketeer wants to ensure that it floats back safely to earth after its voyage.
The average rocket can be used over and again, assuming it isn't damaged when it
returns to the ground and the safety wadding is properly inserted.
"We're building them to recover them," Mr. Hochheimer says.
These rockets return to earth thanks to a collapsed parachute or collection
of streamers tucked above the engine. A smaller number of rockets are built to
either glide back to earth or spin like a helicopter to retard their fall.
The heat generated by the engine normally would tear right through standard
recovery devices, so enthusiasts turn to wadding to form a wall between the
parachute and the engine's churning heat. Readily available wadding --
tissue-paper-like material treated with a fire-retarding chemical -- is the
standard way rocketeers protect their parachutes.
The engines typically have a small charge built into them that releases a
gust of hot gas to trigger whatever's between the motor and nose cone to deploy
the recovery system, he says.
Dave Akin, an associate professor of aerospace engineering with the
University of Maryland, says newer rockets employ backup systems to make sure
the delivery system works as needed.
More sophisticated models use computers to fire the ejection charge based on
barometric readings, Mr. Akin says. "If the [air] pressure goes up and it hasn't
deployed yet, the backup system would trigger it," he says. In some cases, a
radio-controlled trigger can be activated by the rocketeer to eject the
parachute, he adds.
Mr. Barber says the rockets' payload sections also can carry miniaturized
cameras so those on the ground can watch the flight from the rocket's point of
view.
"You can see the ground suddenly pull away," Mr. Barber says.
Mr. Akin says the technology used by model-rocket companies such as Estes
dates back "hundreds of years."
Even the ignition system is a model of simplicity.
Rocketeers run an electrical current through a Nichrome wire, a
high-resistance wire like the heating element in a toaster, which ignites the
fuel, Mr. Akin says.
Some igniter elements are coated with a black material similar to what would
be found on a match head.
"It's easier to ignite, and it burns hotter for a very brief period of
time," he says. "Everything is a variant on electric resistance."
In the past, model rocket fliers could reasonably assess how high their
creations flew with basic trigonometry.
The flier would stand a set distance away from the launch pad, then measure
the angle of flight at its peak using a clinometer and plug those figures into a
mathematical formula to calculate the height reached.
Today, some fliers install tiny computers with pressure sensors that
register how air pressure drops with altitude, data that can tell when the
rocket reached its highest point.
Model-rocket fliers need to act quickly when taking their measurements. The
devices may be a fraction of a real rocket's size, but they can move at speeds
quicker than the eye can catch.
"A typical rocket reaches 100 to 200 miles per hour," Mr. Akin says. "Some
of the high-power rockets can go supersonic" (faster than the speed of sound).
By Christian Toto
THE WASHINGTON TIMES
-----------------------------------------------------------
Flying model rockets may seem like child's play, but tell that to thousands of
science teachers nationwide who lean heavily on the cardboard creations.
In May, more than 500 middle and high school students -- whittled down from
nearly 10,000 contestants -- gathered in The Plains, Va., for the third annual
Team America Rocketry Challenge.
Teachers nationwide incorporated those efforts into their own plans, letting
the rockets' razzle-dazzle sell students on the physics of flight.
Trip Barber, vice president of the National Association of Rocketry, says
the basic physics lifting model rockets into the sky is identical to the forces
applied to genuine rockets.
A rocket kit straight out of the pack might fly to heights around 1,500
feet, says Mr. Barber, whose nonprofit group promotes the educational aspects of
the hobby.
Some rockets can fly much higher, particularly models created by more
skilled rocket enthusiasts.
After 1,500 feet, though, "you can't see it anymore," he says.
The average model rocket weighs less than a pound, thanks to its balsa-wood
fins, cardboard tubing and light plastic nose cone. The rockets fly straight
skyward, in part because of the fins, which are placed strategically on the main
tube and stabilize the flight, much like the feathers that keep an arrow's path
true.
Mary Roberts, technical services manager with Estes Rockets, says model
rocketry is a legally defined term. A rocket must weigh no more than 16 ounces
and contain no more than 4 ounces of propellant, Ms. Roberts says. Rocketeers
can fly models with engines less than or equal to those figures, or they can fly
multistage rockets whose combined thrusting material doesn't outweigh those
standards.
Should a model rocket overstep those bounds, the flier must notify the
Federal Aviation Administration for permission to fly the rocket, she says.
Ms. Roberts says even though her company's models use black powder solid,
not liquid propellant, they still slice through the atmosphere just like the
National Aeronautics and Space Administration's rockets.
The engines themselves are categorized by a letter system in which the total
impulse the craft provides doubles with every letter change. A "B" engine
contains twice the impulse power of an "A" engine, for example, says Ms.
Roberts, whose company has been making model rockets since 1958.
Model rockets start at less than $10, with engines running roughly the same
for a pack of three.
An "A" engine produces up to 2 Newton-seconds of total impulse, she says, a
measurement unit used for rocket speeds that analyzes how many pounds of force
are exerted for one second.
Alexandria resident John Hochheimer, a member of the Northern Virginia
Association of Rocketry, says a garden-variety model rocket can be improved by
using sturdy carbon fiber tubing for the rocket's main body. Most fall back on
the standard balsa and plastic constructs, says Mr. Hochheimer, whose group has
about 130 model-rocket enthusiasts.
Whether the rocket in question took weeks to build or just a few hours, the
rocketeer wants to ensure that it floats back safely to earth after its voyage.
The average rocket can be used over and again, assuming it isn't damaged when it
returns to the ground and the safety wadding is properly inserted.
"We're building them to recover them," Mr. Hochheimer says.
These rockets return to earth thanks to a collapsed parachute or collection
of streamers tucked above the engine. A smaller number of rockets are built to
either glide back to earth or spin like a helicopter to retard their fall.
The heat generated by the engine normally would tear right through standard
recovery devices, so enthusiasts turn to wadding to form a wall between the
parachute and the engine's churning heat. Readily available wadding --
tissue-paper-like material treated with a fire-retarding chemical -- is the
standard way rocketeers protect their parachutes.
The engines typically have a small charge built into them that releases a
gust of hot gas to trigger whatever's between the motor and nose cone to deploy
the recovery system, he says.
Dave Akin, an associate professor of aerospace engineering with the
University of Maryland, says newer rockets employ backup systems to make sure
the delivery system works as needed.
More sophisticated models use computers to fire the ejection charge based on
barometric readings, Mr. Akin says. "If the [air] pressure goes up and it hasn't
deployed yet, the backup system would trigger it," he says. In some cases, a
radio-controlled trigger can be activated by the rocketeer to eject the
parachute, he adds.
Mr. Barber says the rockets' payload sections also can carry miniaturized
cameras so those on the ground can watch the flight from the rocket's point of
view.
"You can see the ground suddenly pull away," Mr. Barber says.
Mr. Akin says the technology used by model-rocket companies such as Estes
dates back "hundreds of years."
Even the ignition system is a model of simplicity.
Rocketeers run an electrical current through a Nichrome wire, a
high-resistance wire like the heating element in a toaster, which ignites the
fuel, Mr. Akin says.
Some igniter elements are coated with a black material similar to what would
be found on a match head.
"It's easier to ignite, and it burns hotter for a very brief period of
time," he says. "Everything is a variant on electric resistance."
In the past, model rocket fliers could reasonably assess how high their
creations flew with basic trigonometry.
The flier would stand a set distance away from the launch pad, then measure
the angle of flight at its peak using a clinometer and plug those figures into a
mathematical formula to calculate the height reached.
Today, some fliers install tiny computers with pressure sensors that
register how air pressure drops with altitude, data that can tell when the
rocket reached its highest point.
Model-rocket fliers need to act quickly when taking their measurements. The
devices may be a fraction of a real rocket's size, but they can move at speeds
quicker than the eye can catch.
"A typical rocket reaches 100 to 200 miles per hour," Mr. Akin says. "Some
of the high-power rockets can go supersonic" (faster than the speed of sound).
