C8 EZ RE THE WASHINGTON POST.MONDAY, MAY 2 , 2022
kidspostCHIP SAYS
The white streaks in the sky left by airplanes are
called contrails. They occur because water vapor
condenses around soot from the plane’s exhaust
and freezes.
KIDSPOST.COM
Mother’s Day is Sunday!
Look for homemade gift
ideas in our online Crafts
and Recipes section.TODAY
The first Monday of May may feature
early morning showers and then
sunny weather in the upper 70s.
ILLUSTRATION BY COLT HARPER, 8, ARLINGTONBIRTHDAYS OF THE WEEKMONDAY, MAY 2
Columbia’s Malcolm Baber-Lucero
(2012).
Gaithersburg’s Jake Fisher (2011).
Silver Spring’s Alexandra Hughes
and Brooke Hughes (2009).
Soccer player David Beckham (1975).
Actor Dwayne “The Rock” Johnson
(1972).
Inventor Elijah McCoy (1844).TUESDAY, MAY 3
Actress Rachel Zegler (2001).
Animator Joe Murray (1961).
Author Dodie Smith (1896).
WEDNESDAY, MAY 4
Springfield’s Patrick Doherty (2010).
Rockville’s Anna Fort (2009).
Actress Audrey Hepburn (1929).
Educator Horace Mann (1796).
THURSDAY, MAY 5
Singer Adele (1988).
Saxophonist Edward Jordan (1935).
Journalist Nellie Bly (1864).FRIDAY, MAY 6
Fairfax’s Landon Johnson (2016).
Director Orson Welles (1915).
Chemist Victor Grignard (1871).
Geologist Grove Gilbert (1843).SATURDAY, MAY 7
Ashburn’s Mirabelle Niermann
(2013).
Washington’s Claire Huseby (2011).
Reston’s Drew Hull (2009).
Poet Robert Browning (1812).
SUNDAY, MAY 8
The Capitals’ Lars Eller (1989).
President Harry Truman (1884).
Poet Phillis Wheatley (1753).Baber-Lucero Fisher
A. Hughes
Birthday announcements are for ages 6 to 13 and
are printed on a first-come, first-served basis.
They do not appear online. A parent or legal guardian
must give permission. We need photos at least
three weeks ahead of publication. We need
names (if photos are not desired) at least a week
before publication. Fill out the online form at wapo.st/
kidspostbirthdays. We are temporarily unable to
accept mailed submissions. Questions? Contact
[email protected].B. HughesDoherty Fort
Johnson Niermann
BY GALADRIEL WATSON“If you take a regular piece of
paper and try to make it fly, it will
flutter, tumble, flip around in the
air and do all sorts of crazy mo-
tions,” says Leif Ristroph, an asso-
ciate professor of mathematics at
New York University. But if you
fold it into a paper airplane, “the
magic of it is that it doesn’t do all
those things,” he says. “It will fly
smoothly.” This awesome ability
is why he’s so keen on paper
airplanes. His office is filled with
books about them.
But how smoothly can they fly?
Ristroph and a team of fellow
scientists decided to test this for
the benefit of science.
“To try to understand the math
and physics involved, we decided
to go simple,” Ristroph says — so
simple that their “paper air-
planes” were just small sheets of
paper, 2 inches long by 6 inches
wide, sometimes left perfectly flat
and sometimes folded a wee bit
on each side to give them fins.
They experimented with ad-
justing each plane’s “center of
mass,” the place where it would
balance on the edge of a ruler
without tipping over. On their
paper plane, this occurred exactly
in the middle of the sheet, but the
plane didn’t fly well.
They wondered what would
happen if they adjusted the cen-
ter of mass forward? To do so,
they placed a thin strip of copper
tape on the plane, always keeping
the plane balanced on its left and
right sides (otherwise, it would
turn). They discovered that, if the
tape was too far toward the front
of the plane, the plane nosedived.
If it was too far back, the plane
bounced.
Then they hit the right spot:
“exactly halfway between the
middle of the sheet and the front
end of the sheet.” Not only did thisproduce the smoothest glide, but
it enabled the plane to fly the
farthest horizontally before land-
ing.
They also found similar results
by making thin plastic plates “fly”
underwater, since water is gov-
erned by the same physics and
math as air. And they made a
computer model that let them
predict how different paper air-
planes would perform.
But why study paper air-
planes?
What’s amazing about them,
Ristroph says, “is that there’s no
tail that’s needed.” Most birds and
airplanes rely on their tails to
keep level while flying. Their
wings are used to generate “lift,”which is the force that overcomes
gravity’s tendency to pull objects
down. Unless it has a fancy tailed
design, “a paper airplane does
this all in one,” he says.
“I doubt our discoveries will
change the way passenger air-
planes are designed,” Ristroph
says. However, “it could be more
useful as we start to think about
very, very small flying aircraft,”
such as flying robots and tiny
drones for helping search-and-
rescue teams or monitoring air
quality above cities. Because they
may be too small to fit separate
lift and stability mechanisms,
perhaps they can offer them to-
gether as a simple paper airplane
does.Kids can also benefit from Ris-
troph’s research. For the typical
paper airplane — with paper fold-
ed into a triangular shape —
Ristroph suggests experimenting
like he did to make it fly smoothly.
Put a paper clip on the body of the
plane, the place where you hold it
to launch it. Try putting the clip in
various spots, forward and back-
ward.
“For each location that you put
it at, see what you get in terms of
the flight — whether it’s smooth
and steady, or whether it’s kind of
bucking up and down or doing
something else.” Sooner or later,
you should hit the perfect posi-
tion and the airplane will grace-
fully soar.Why flying paper planes is serious fun for scientistsISTOCK
Scientist Leif Ristroph says studying paper airplanes could aid in the design of drones or flying robots.Huseby Hull
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