An excellent worksheet for Aviation MB can be found at meritbadge.com
PDF: http://meritbadge.com/files/mb-pdfs/Aviation.pdf
RTF: http://meritbadge.com/files/mb-docs/Aviation.doc
New requirements for Aviation MB became effective on January 1,
2007. I will be updating this site to incorporate
those changes. Please bear with me while
I try to improve some references while updating.
The USSCOUTS.ORG has Excellent Worksheets with the new requirements:
John “Gator” Wallin has produced an excellent PowerPoint presentation
for the Aviation MB using files found here and adding some neat files of his
own. Here it is for your use. This is a LARGE (1MB) file. All John asks is that you retain his credits
slide: AVIATION MB POWERPOINT
PRESENTATION (1MB FILE)
2007
REQUIREMENTS (please
follow the hyperlinks during this changeover
period)
1. Do the following:
a. Define "aircraft". Describe some kinds and uses of aircraft today. Explain the operation of piston, turboprop, and jet engines.
b.
Point out on a model airplane the forces that
act on an airplane in flight.
c. Explain how an airfoil
generates lift, how the primary control surfaces (ailerons, elevators, and
rudder) affect the airplane’s attitude, and how a propeller produces thrust.
d. Demonstrate how the control surfaces of an airplane are used for takeoff, straight
climb, level turn, climbing turn, descending turn,
straight descent, and landing.
e.
Explain the following: the recreational pilot and
the private
pilot certificates; the instrument
rating.
2. Do TWO of the following:
a. Take a flight in an aircraft with your parent's permission. Record the date, place, type of aircraft, and duration of flight, and report on your impressions of the flight.
b. Under supervision, perform
a preflight inspection of a light airplane.
c. Obtain and
learn how to read an aeronautical chart. Measure a true course on the chart.
Correct it for magnetic variation, compass deviation, and wind drift. Arrive at
a compass heading.
d. Using one
of many flight simulator software packages available for computers. "fly" the course and heading you established in
requirement 2c or another course you have plotted.
e. On a map, mark a route for an imaginary
airline trip to at least three different locations. Start from the commercial
airport nearest your home. From timetables (obtained from agents or online from
a computer, with your parent's permission), decide when you will get to and
leave from all connecting points. Create an aviation flight plan and itinerary
for each destination.
f. Explain the purposes and functions of the various instruments found in a typical single-engine aircraft: attitude indicator, heading indicator, altimeter, airspeed indicator, turn and bank indicator, vertical speed indicator, compass, navigation (GPS and VOR) and communication radios, tachometer, oil pressure gauge, and oil temperature gauge.
g. Create an original poster of an aircraft instrument panel. Include and identify the instruments and radios discussed in requirement 2f.
3.
Do ONE of the following:
a. Build and fly a fuel-driven model airplane. Describe safety rules for building and flying model airplanes Tell safety rules for use of glue, paint, dope, plastics, fuel, and battery pack.
b. Build a model FPG-9. Get others in your troop or patrol to make their own model, then organize a competition to test the precision of flight and landing of the models.
4.
Do ONE of the following:
a.
Visit an airport.
After the visit, report on how the facilities are used, how runways are
numbered, and how runways are determined to be "active."
b.
Visit a Federal Aviation Administration facility—a
control tower, terminal radar control facility, air route traffic control
center, flight service station, or Flight Standards District Office. (Phone
directory listings are under U.S. Government Offices, Transportation
Department, Federal Aviation Administration. Call in
advance.) Report on the operation and your impressions of the facility.
c.
Visit an aviation museum or attend an air show.
Report on your impressions of the museum or show.
5. Find out about three career
opportunities there are in
aviation. Pick one and find out the education, training, and experience
required for this profession. Discuss this with your counselor, and explain why
this profession might interest you.
BSA
Advancement ID#: 25
Pamphlet Revision Date: 2006
Requirements last updated in 2007
OLDER
REQUIREMENTS
1. Do the
following:
a. Define "aircraft". Describe some kinds and uses of aircraft today. Explain the operation of piston, turboprop, and jet engines.
b. Point out on a model airplane the forces that act on an airplane in flight.
c. Explain how an airfoil generates lift, how the
primary control surfaces (ailerons, elevators,
and rudder) affect the airplane’s attitude, and how a propeller
produces thrust.
d. Demonstrate how the control surfaces of an airplane are used for
takeoff, straight climb, level turn, climbing turn,
descending turn, straight descent, and landing.
e. Explain the following: the recreational pilot and the private
pilot certificates; the instrument rating.
f. Find out what job opportunities
there are in aviation. Describe the qualifications and working conditions of
one job in which you are interested. Tell what it offers for reaching your goal
in life.
2. Do TWO of
the following:
a. Take a flight in an aircraft. Record the date, place, type of aircraft, and duration of flight, and report on your impressions of the flight.
b. Visit an airport. After the visit, report on how
the facilities are used, how runways are numbered, and how runways are
determined to be "active."
c. Visit a Federal Aviation Administration facility—a
control tower, terminal radar control facility, air route traffic control
center, flight service station, or Flight Standards District Office. (Phone
directory listings are under U.S. Government Offices, Transportation
Department, Federal Aviation Administration. Call in
advance.) Report on the operation and your impressions of the facility.
d. Visit an aviation museum or attend an air show. Report
on your impressions of the museum or show.
e. Explain the purposes and functions of the various instruments found in a typical single-engine aircraft: attitude indicator, heading indicator, altimeter, airspeed indicator, turn and bank indicator, vertical speed indicator, compass, navigation (GPS and VOR) and communication radios, tachometer, oil pressure gauge, and oil temperature gauge.
f.
Visit an aircraft maintenance shop. Interview a technician and report on
his/her ideas about aircraft maintenance.
g. Create an original poster of an aircraft instrument panel. Include and identify the instruments and radios discussed in requirement 2e.
5. Do TWO
of the following:
d. Interview
a professional or military pilot. Report on what you
learned.
b.
Interview a flight attendant. Report on what you learned.
c.
Interview a certified flight instructor. Report on what
you learned.
d.
Under supervision, perform a preflight inspection of a
light airplane.
e. Obtain and learn how to read an aeronautical chart. Measure a true course on the chart. Correct it for magnetic variation, compass deviation, and wind drift. Arrive at a compass heading.
f. Using one of many flight simulator software packages available for computers, “fly” the course and heading you established in requirement 3e or another course you have plotted.
g. On a map, mark a route for an imaginary airline trip to at least three foreign countries. Start from the commercial airport nearest your home. From timetables (obtained from agents or online from a computer), decide when you will get to and leave from all connecting points.
h. Build and fly a fuel-driven model airplane. Describe safety rules for building and flying model airplanes Tell safety rules for use of glue, paint, dope, plastics, and fuel.
32 Assemble
a poster (or album) of original photographs taken while accomplishing the
requirements.
BSA Advancement
ID#: 25
Pamphlet
Revision Date: 2000
Source:
Boy Scout Requirements, #33215D, revised 2004
"When once you
have tasted flight, you will forever walk the earth with your eyes turned
skyward, for there you have been, and there you will always long to
return."
--Attributed to Leonardo da Vinci (Unconfirmed)
I Want to Be a Pilot
I
want to be a pilot when I grow up because it’s fun and easy to do. Pilots don’t need much school,
they just have to learn numbers so they can read the instruments. I guess they should be able to read maps so
they can find their way if they get lost.
Pilots should be brave so they won’t get scarred if it’s foggy and they
can’t see or if a wing or motor falls off they should stay calm so they’ll know
what to do. Pilots have to have good
eyes so they can see through clouds and they can’t be afraid of lighting or
thunder because they are closer to them then we are. The salary pilots make is another thing that
I like. They make more money than they
can spend. This is because most people
think airplane flying is dangerous except pilots don’t because they know how
easy it is. There isn’t much I don’t
like, except girls like pilots and all the stewardesses want to marry them so
they always have to chase them away so they won’t bother them. I hope I don’t get airsick because if I do I
couldn’t be a pilot and would have to go to work.
A Fifth Grader
Define Aircraft
According to Webster’s Ninth New Collegiate Dictionary, an aircraft is “a
weight-carrying structure for navigation of the air that is supported either by
its own buoyancy or by the dynamic action of the air against its
surfaces.” The Federal Aviation
Administration (FAA) simplifies this definition to “a device that is used or
intended to be used for flight in the air.”
For pilot certification purposes the
FAA divides aircraft in to the following categories: lighter-than-air, glider,
airplane, rotorcraft, and a fairly new category, powered-lift.
Lighter-than-air
The first type of aircraft that flew were lighter-than-air aircraft. They use a light-weight “envelope” to contain
a volume of gas that is lighter than the surrounding air, making the craft
buoyant. Lighter-than-air aircraft are
divided into two classes: balloons and airships. Balloons can be either “hot air” or
gas-filled.
Balloons
Hot air is less dense than cold air,
in other words, you could say it weighs less.
The contained hot air
makes the balloon buoyant.
Normally, the bigger the envelope, the more weight the balloon can carry
aloft. Hot air balloons must carry fuel
to burn in powerful heaters to keep the air in the envelope hot. Their airborne
time is limited by the amount of fuel they can carry. The hot air balloon’s altitude is normally
controlled by how hot the air in the envelope is—the hotter, the higher. Direction of flight is almost totally
dependent on the direction of the wind.
The balloon pilot will use different altitudes to find a desirable wind
current. To make a rapid descent, and
for landings, the pilot will vent the hot air through special openings in the
envelope.
Gas balloons will use a lifting gas
that is lighter than air, such as helium or hydrogen. Most modern day gas balloons will use helium
since hydrogen is extremely flammable.
The French brothers Etienne and Joseph
Montgolfier built the first hot air balloon in
1783. On
The
National Eagle Scout Association and
Order
of the Arrow hot air balloons at the
2001
National Boy Scout Jamboree
The Breitling
Orbiter 3, a gas-filled balloon.
The Orbiter 3 was the first balloon to
circumnavigate the globe non-stop.
You
can find more information on the Orbiter 3 at:
http://www.breitling.com/eng/aero/orbiter/
Airships
An airship is a lighter-than air aircraft that has
propulsion and steering. Airships generally use gas filled envelopes, but there
are a few hot air (thermal) airships around. Airships can be divided into two
classes, rigid and non-rigid hulls.
Rigid hull airships are known as dirigibles or zeppelins. Non-rigid hull airships are called blimps. Dirigibles use separate gas-bags within the
main envelope, or hull. Their hull is
further divided into useful compartments.
The German airships the Graf Zeppelin, and the Hindenburg, were flying
luxury hotels, with staterooms and dining rooms as well as cargo areas within
the hull.
You can see above how large
the Graf Zeppelin was in relation to a 747 and the HMS Titanic. The picture on the left is a cutaway view of
the envelope showing the internal layout.
The lifting-gas would be carried in separate bladders within the
envelope. The picture on the right shows
one of the luxurious dining rooms aboard the Graf Zeppelin
Gliders
Gliders are also referred to as
sailplanes, and the sport of flying sailplanes is referred to as soaring. Sailplanes get their lift by using gravity
as their propulsion. Sailplanes normally
have sleek, long, very efficient wings. Some sailplanes can glide for over 60
miles from an altitude of 1 mile.
Sailplanes use hot air too. Soarers look for thermals, or rising air currents, to help
them gain altitude in order to soar even farther. The world record for distance flown is well
over 1000 miles and sailplanes have climbed to over 50,000 feet. Sailplanes may
be launched from the ground by tow vehicles or winches. Many places use tow aircraft to haul the
sailplane to altitude. Gliders, towed by
C-47 cargo aircraft, were used in World War II to haul troops and equipment
into enemy territory.
Sailplane
over
http://www.ssa.org/AboutGliding.asp
Airplanes
The Wright
Flyer became the first powered, heavier-than-air machine to achieve
controlled, sustained flight with a pilot aboard. Orville Wright flew the 1st
successful flight on
That
first flight lasted all of 12 seconds and covered a distance of 120 feet (less
than the wingspan of some modern airliners). The airplane flew three more times
that day, with Orville and his brother Wilbur trading places as pilot. Wilbur
had the longest flight that day; it was 852 feet and lasted 59 seconds.
Check out this site to see
an organization attempting to duplicate the Wright Flyer for the 100th
anniversary of powered flight: http://www.wrightflyer.org/
Rotorcraft
Rotorcraft can be divided into two classes,
helicopters and gyroplanes.
Gyroplanes
Gyroplanes
have been around for decades. Gyroplanes
are also known as gyrocopters, gyrodynes, autogyros, and autogiros. They were the first rotary wing
aircraft to fly. Gyroplanes look like a
cross between an airplane and a helicopter.
A gyroplane has a fuselage like an airplane, and a propeller like an
airplane to provide the propulsion, but it gets its lift by a rotor similar to
that in a helicopter. Unlike the rotor
in a helicopter, the rotor in an autogyro is not
powered. It is made to spin by
aerodynamic forces. This type of spinning is known as autorotation.
Helicopters
Pictured is an
MH-53J “Pave Low” Helicopter from the 20th Special Operations Squadron
at
Helicopters fly by creating lift with a rotary wing. The helicopter gets its forward movement by tilting its rotor. In order to compensate for the torque created by the main rotor, helicopters use a tail rotor to provide directional stability.
More
information on how helicopters fly along with interesting facts and links can
be found at: http://www.helis.com/howflies/
Powered Lift
Powered-lift
aircraft are capable of taking off and landing like a helicopter, but, once
airborne, its engine nacelles can be rotated to convert the aircraft to an
airplane capable of high-speed, high-altitude flight.
(PLEASE NOTE: The great majority of the following material was found on: http://www.allstar.fiu.edu/. I need to give credit where it is due, and the Aeronautics Learning Laboratory for Science, Technology, and Research (ALLSTAR) at Florida International University is due all the credit. The material on their site is extensive and illustrates many items better than I would be able to do. I have edited some of the text for brevity, clarification, and to fit within the MB requirements.)
The piston engine is also referred to as a “reciprocating-engine” in an aircraft. Some times you may hear it referred to as a “recip”.
RECIPROCATING-ENGINE
OPERATING PRINCIPLES
Because the fuel mixture is burned within the
engine the reciprocating engine is also known as an internal-combustion engine.
To understand how a reciprocating engine works, we must first study its parts
and the functions they perform.
The
seven major parts are:
32 The cylinders
(2)
The pistons
(3)
The connecting rods
(4)
The crankshaft
(5)
The valves
(6)
The spark plugs
(7)
A valve operating mechanism (cam).
Refer
to the relative location of these parts in Figure 6-2.
Engine
Operation.
The cylinder is closed on one end (this is
called the cylinder head), and the piston fits snugly in the cylinder. The
piston wall is grooved to accommodate rings, which fit tightly against the
cylinder wall and help seal the cylinder’s open end so that gases cannot escape
from the combustion chamber. The combustion chamber is the area between the top
of the piston and the head of the cylinder when the piston is at its uppermost
point of travel.
The up-and-down movement of the piston is converted to rotary motion to turn the propeller by the connecting rod and the crankshaft, just as in most automobiles.
Note
the crankshaft, connecting rod, and piston arrangement in Figure 6- 2 and
imagine how the movement of the piston is converted to the rotary motion of the
crankshaft. Note particularly how the connecting rod is joined to the
crankshaft in an offset manner.
The valves at the top of the cylinder open
and close to let in a mixture of fuel and air and to let out, or exhaust,
burned gases from the combustion chamber. A cam geared to the crankshaft opens and
closes the valve. This gearing arrangement ensures that the two valves open and
close at the proper times.
32 The Intake Stroke
The cycle begins with the piston at top
center; as the crankshaft pulls the piston downward, a partial vacuum is
created in the cylinder chamber. The cam arrangement has opened the intake
valve, and the vacuum causes a mixture of fuel and air to be drawn into the
cylinder.
2.
& 3. Compression and Ignition Stroke
As the crankshaft drives the piston upward
in the cylinder, the fuel and air mixture is compressed. The intake valve has
closed, of course, as this upward stroke begins. As the compression stroke is
completed and just before the piston reaches its top position, the compressed
mixture is ignited by the spark plug.
4.
Power Stroke
The very hot gases expand with tremendous
force, driving the piston down and turning the crankshaft. The valves are
closed during this stroke also.
5.
Exhaust Stroke
On the second upward (or outward, according
to the direction the unit is pointed) stroke, the exhaust valve is opened and
the burned gases are forced out by the piston.
At the moment the piston completes the
exhaust stroke, the cycle is started again by the intake stroke. Each piston
within the engine must make four strokes to complete one cycle, and this
complete cycle occurs hundreds of times per minute as the engine runs.
Reciprocating-Engine Horsepower.
Most persons are acquainted with the term
horsepower as applied to automobile and aircraft reciprocating engines. The
term was coined by James Watt, the inventor of the steam engine, who wished to
evaluate the power output of his steam engine. Watt hitched a horse to an
apparatus and determined that the horse
could
lift 550 pounds one foot in one second. Thus, one horsepower became the power
to lift 550 pounds one foot per second, or 33,000 foot-pounds per minute (550 x
60).
If an aircraft reciprocating engine is rated
at 150 horsepower, it means the engine is capable of producing this much power.
However, the engine has to be running at a certain speed before that much power
is produced. The same is true for all other types of reciprocating engines.
TURBOPROP ENGINES
The turboprop engine is an effort to combine the best features of turbojet and propeller aircraft. The first is more efficient at high speeds and high altitudes; the latter is more efficient at speeds under 400 mph and below 30,000 feet. The turboprop uses a gas turbine to turn a propeller. Its turbine uses almost all the engine’s energy to turn its compressor and propeller, and it depends on the propeller for thrust, rather than on the high-velocity gases going out of the exhaust. Strictly speaking, it is not a jet. Study Figure 6-9 and note how the turbine turns the compressors and the propeller.
The gas turbine can turn a propeller with
twice the power of a reciprocating engine. Reduction gears slow the propeller
below the turbine’s rpm, and this must be done because of the limitations of
propellers. That is, no propeller is capable of withstanding the forces
generated when it is turned at the same rate as that of the gas turbine. Even
so, the turboprop engine receives fairly extensive use in military and civilian
aviation circles.
In summary, aircraft turbine engines may
be classified as turbojet, turbofan, or turboprop. As a group, the turbine
engines have many advantages over reciprocating engines, the most obvious being
the capability of higher-altitude and higher-speed performance. Vibration
stress is relieved as a result of rotating rather than reciprocating parts. Control
is simpler because one lever controls both speed and power. With the large
airflow, cooling is less complicated. Spark plugs are used only for starting,
and the continuous ignition system of reciprocating engines is not needed. A
carburetor and mixture control are not needed.
The major disadvantages have been the high
fuel consumption and poor performance at low power setting, low speeds, and low
altitudes. Turboprop and turbofan developments have greatly improved aircraft
turbine engines in these areas.
Turbojet
The turbojet uses a series of fan-like compressor
blades to bring air into the engine and compress it. An entire section of the
turbojet engine performs this function, which can be compared to the
compression stroke of the reciprocating engine. In this section, there is a
series of rotor and stator blades. Rotor blades perform somewhat like
propellers in that they gather and push air backward into the engine. The
stator blades serve to straighten the flow of this air as it passes from one
set of rotor blades to the next (see figure 6-7 ).
As the air continues to be forced further
into the engine, it travels from the low-compression set of rotors and stators to
the high-compression set. This last set puts what we might say is the final
squeeze on the air.
The combustion chamber receives the
high-pressure air, mixes fuel with it, and burns the mixture. The hot, very
high-velocity gases produced strike the blades of the turbine and cause it to
spin rapidly. The turbine is mounted on a shaft, which is connected to the
compressor. Thus, the spinning is what causes the compressor sections to
function. After passing the turbine blades, the hot, highly accelerated gases
go into the engine’s exhaust section.
The exhaust section of the jet engine is
designed to give additional acceleration to the gases and thereby increase
thrust. The exhaust section also serves to straighten the flow of the gases as
they come from the turbine. Basically, the exhaust section is a cone mounted in
the exhaust duct. This duct is also referred to as the tailpipe. The shape of
the tailpipe varies, depending on the design operating temperatures and the
speed-performance range of the engine.
With all the heat produced in the turbojet
engine, you probably wonder how it is kept from overheating. Like most aircraft
reciprocating engines, the jet is also air-cooled. Of all the air coming into
the compressor section, only about 25 percent is used to produce thrust; the
remaining 75 percent passes around the combustion chamber and turbine area to
serve as a coolant.
TURBOFAN
The
turbofan engine has gained popularity for a variety of reasons. As shown in
Figure 6-8, one or more rows of compressor blades extend beyond the normal
compressor blades. The result is that four times as much air is pulled into the
turbofan engine as in the simple turbojet. However, most of this excess air is
ducted through bypasses around the power section and out the rear with the
exhaust gases. Also, a fan burner permits the burning of additional fuel in the
fan airstream. With the burner off, this engine can
operate economically and efficiently at low altitudes and low speeds. With the
burner on, the thrust is doubled by the burning fuel, and it can operate on
high speeds and high altitudes fairly efficiently. The turbofan has greater
thrust for takeoff, climbing, and cruising using the same amount of fuel than
the conventional turbojet engine.
With better
all-around performance at a lower ate of fuel consumption, plus less noise
resulting from its operation, it is easy to understand why most new jet-powered
airplanes are fitted with turbofan engines. This includes military and civilian
types.
Jet Engine Thrust
The force
produced by a jet engine is expressed in terms of “pounds of thrust”. This is a
measure of the mass or weight of air moved by an engine times the acceleration of
the air as it goes through the engine. Technically, if the aircraft were to
stand still and the pressure at the exit plane of the jet engine was the same
as the atmospheric pressure, the formula for the jet engine thrust would be:
weight of air in pounds per second X velocity
Thrust =
--------------------------------------------------------------
32.2 (normal acceleration due to
gravity, in feet per second2)
Imagine an
aircraft standing still, capable of handling 215 pounds of air per second.
Assume the velocity of the exhaust gases to be 1,500 feet per second. The
thrust would then be:
215 lbs of air per second X 1,500 feet per second
Thrust =
-------------------------------------------------------------- = 322500/32.2 = Thrust = 10,016 lbs
32.2
It is not
very practical to try to compare jet engine output in terms of horsepower. As a
rule of thumb, however, you might remember that at 375 miles per hour (mph),
one pound of thrust equals one horsepower; at 750 mph, one pound of thrust
equals two horsepower.
Forces Acting on an Airplane
Here’s a picture of a United States Air Force Thunderbirds F-16 to help point out the main forces that act on an airplane.
More information on the Thunderbirds can be found at: http://www.airforce.com/thunderbirds/index.htm
Lift is produced by a lower
pressure created on the upper surface of an airplane’s wing compared to the
pressure on the wing’s lower surface, causing the wing to be “lifted” upward.
The special shape of the airplane wing (airfoil) is designed so that air
flowing over it will have to travel a greater distance faster, resulting in a
lower pressure area (see illustration) thus lifting the wing upward. Lift is
that force which opposes the force of gravity (or weight).
Thrust is a force created by a
power source which gives an airplane forward motion. It can either “pull” or
“push” an airplane forward. Thrust is that force which overcomes drag.
Conventional airplanes utilize engines as well as propellers to obtain thrust.
Drag is the force which delays
or slows the forward movement of an airplane through the air when the airflow
direction is opposite to the direction of motion of the airplane. It is the
friction of the air as it meets and passes over and about an airplane and its
components. The more surface area exposed to rushing air, the greater
the
drag. An airplane’s streamlined shape helps it pass through the air more
easily.
If
the plane flies with a tail wind, that is, a wind whose airflow is also acting
in the same direction as the direction of motion of the aircraft, the “drag”
actually helps move the aircraft in the direction it wants to go. However, during takeoffs and landings,
aircraft normally fly into the wind.
Lift
PLEASE NOTE:
Recently I have received some emails
pointing out that there is some evidence that lift is more a result of Newton’s
Laws of motion and the “downwash” produced by wings than Bernoulli’s
Principle. In all fairness, I am
providing this link to the Glenn Research Center’s web site with some very
interesting “new” evidence on lift.
Please visit this site and explore the interesting debate about lift
with in the scientific community. Even
the experts can’t agree!
NASA’s
Glenn Research Center:
http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
BERNOULLI’S
PRINCIPLE
Daniel Bernoulli, an eighteenth-century
Swiss scientist, discovered that as the velocity
of a fluid increases, its pressure decreases. How and why does this work,
and what does it have to do with aircraft in flight?
Bernoulli’s principle can be seen most easily through the use of a venturi tube. A venturi tube is
simply a tube which is narrower in the middle than it is at the ends. When the
fluid passing through the tube reaches the narrow part, it speeds up. According
to Bernoulli’s principle, it then should exert less pressure. Let’s see how
this works.
As the fluid passes over the central part
of the tube more energy is used up as the molecules accelerate. This leaves
less energy to exert pressure, and the pressure thus decreases. One way to
describe this decrease in pressure is to call it a differential pressure. This
simply means that the pressure at one point is different from the pressure at
another point. For this reason, the principle is sometimes called Bernoulli’s
Law of Pressure Differential.
Bernoulli’s principle states that an
increase in the velocity of any fluid is always accompanied by a decrease in
pressure. Air is a fluid. If you can cause the air to move rapidly on one side
of a surface, the pressure on that side of the surface is less than that on its
other side. Bernoulli’s principle works with an airplane wing. In motion, air
hits the leading edge (front edge) of the wing. Some of the air moves under the
wing, and some of it goes over the top. The air moving over the top of the
curved wing must travel farther to reach the back of the wing; consequently it
must travel faster than the air moving under the wing, to reach the trailing
edge (back edge) at the same time. Therefore the air pressure on the top of the
wing is less than that on the bottom of the wing.
Bernoulli’s principle
applies to any fluid, and since air is a fluid, it applies to air. The camber of an airfoil
causes an increase in the velocity of the air passing over the airfoil.
This results in a decrease in the pressure in the stream of air moving over the airfoil. This decrease in pressure on the top of the airfoil causes lift.
Control Surfaces
Control
surfaces are
the moveable outer surfaces of an airplane. These surfaces control the flow of
air over the various sections of the aircraft causing it to move in different
ways. Inside the airplane, pilots control the movement of the surfaces with
their hands or feet by pushing, pulling or turning the controls to make the
airplane
move
in the proper manner.
By
learning the names and functions of the various surfaces, you will appreciate
the construction, design, and aerodynamics of the airplane.
AIRPLANE
An airplane is a vehicle heavier than air, powered
by an engine, which travels through the air by the reaction of air passing over
its wings.
FUSELAGE
The fuselage is the central
body portion of an airplane, which accommodates the crew and passengers or
cargo.
COCKPIT
In general aviation airplanes, the cockpit is
usually the space in the fuselage for the pilot and the passengers: in some
aircraft it is just the pilot’s compartment.
LANDING GEAR
The landing gear, located underneath the
airplane, supports it while on the ground.
WINGS
Wings are the parts of airplanes which provide lift
and support the entire weight of the aircraft and its contents while in
flight.
PROPELLER
A propeller is a rotating blade located on the front
of the airplane. The engine turns the propeller which most often pulls the
airplane through the air.
FLAPS
Flaps are the movable sections of an airplane’s
wings closest to the fuselage. They are moved in the same direction (down) and
enable the airplane to fly more slowly.
AILERONS
Ailerons are the outward movable sections of an airplane’s
wings which move in opposite directions (one up, one down). They are used in
making turns.
RUDDER
The rudder is the movable
vertical section of the tail which controls lateral movement.
HORIZONTAL STABILIZER
The horizontal stabilizer
is the horizontal surface of the aft part of the fuselage used to balance the
airplane.
ELEVATOR
The elevator is the
movable horizontal section of the tail which causes the plane to move up and
down.
PROPELLERS
We can say that the propeller is the action
end of an aircraft’s piston or turboprop engine, because it converts the useful
energy of the engine into thrust as it spins around and around. The propeller
has the general shape of a wing, but the camber and chord (curvature and
cross-sectional length) of each section of the propeller are different. The
wing provides lift upward, while the propeller provides lift forward.
The wing has only one motion, which is
forward, while the propeller has forward and rotary motion. The path of these
two motions is like a corkscrew as the propeller goes through the air.
Like a wing, a propeller blade has a thick
leading edge and a thin trailing edge. The blade back is the curved portion and
is like the top of a wing. The blade face is comparatively flat and corresponds
to the underside of a wing. The blade shank is thick for strength and fits into
a hub, which is attached to the crankshaft directly or indirectly. The outer
end of the blade is called the tip.
Blade pitch is loosely defined as the angle
made by the chord of the blade and its plane of rotation. When the angle is
great, the propeller is said to have high pitch. A high-pitch propeller will
take a bigger bit of air and move the aircraft farther forward in one rotation
than will a low-pitch propeller.
Blade pitch is loosely defined as the angle made by
the chord of the blade and its plane of rotation. When the angle is great, the
propeller is said to have high pitch. A high-pitch propeller will take a bigger
bit of air and move the aircraft farther forward in one rotation than will a
low-pitch propeller. Propellers may be
classified as to whether the blade pitch is fixed or variable. The demands on
the propeller differ according to circumstances. For example, in takeoffs and
climbs more power is needed, and this can best be provided by low pitch. For
speed at cruising altitude, high pitch will do the best job. A fixed-pitch
propeller is a compromise.
There are two types of variable-pitch propellers
adjustable and controllable. The adjustable propeller’s pitch can be changed
only by a mechanic to serve a particular purpose-speed or power. The
controllable-pitch propeller permits pilots to change pitch to more ideally fit
their requirements at the moment. In different aircraft, this is done by
electrical or hydraulic means. In modern aircraft, it is done automatically,
and the propellers are referred to as constant-speed propellers. As power
requirements vary, the pitch automatically changes, keeping the engine and the
propeller operating at a constant rpm. If the rpm rate increases, as in a dive,
a governor on the hydraulic system changes the blade pitch to a higher angle.
This acts as a brake on the crankshaft. If the rpm rate decreases, as in a
climb, the blade pitch is lowered and the crankshaft rpm can increase. The
constant-speed propeller thus ensures that the pitch is always set at the most
efficient angle so that the engine can run at a desired constant rpm regardless
of altitude or forward speed.
The constant-speed propellers have a full-feathering capability. Feathering means to turn the blade approximately parallel with the line of flight, thus equalizing the pressure on the face and back of the blade and stopping the propeller. Feathering is necessary if for some reason the propeller is not being driven by the engine and is windmilling, a situation that can damage the engine and increase drag on the aircraft.
Most
controllable-pitch and constant-speed propellers also are capable of being
reversed. This is done by rotating the blades to a negative or reverse pitch.
Reversible propellers push air forward, reducing the required landing distance
as well as reducing wear on tires and brakes.
How Control Surfaces Are Used
DIRECTIONAL CONTROL
An
airplane in flight changes direction by movement around one or more of its
three axes of rotation: lateral axis, vertical axis, and longitudinal axis.
These axes are imaginary lines that run perpendicularly to each other through
the exact weight center of the airplane. The airplane’s rotation around them is
called pitch, roll, and yaw. The pilot guides the airplane by controlling
pitch, roll, and yaw, and by use of the elevators, ailerons, and rudder.
YAW Rudder rotates the airplane around vertical axis.
ROLL Ailerons rotate the airplane
around longitudinal axis.
PITCH Elevators rotate airplane around lateral axis.
The
Vertical Axis – Yaw
Rudder: The foot pedals are connected by means of
wires or hydraulics to the rudder of the tail section. The rudder is the
vertical part of the tail that can move from side to side.
When the foot pressure on the left rudder
pedal moves the rudder to the left, causing the nose of the airplane to move to
the left.
When the foot pressure on the right rudder
pedal moves the rudder to the right, causing the nose of the airplane to move to
the right.
The
Longitudinal Axis – Roll
Ailerons: The stick is connected by means of wires or
hydraulics to the wings’ ailerons. By turning the stick, the pilot can change
the positions of the ailerons.
When the control wheel is turned to the right,
the right aileron goes up and the left aileron goes down,
rolling the airplane to the right.
When the control wheel is turned to the left,
the right aileron goes down and the left aileron goes up, rolling the airplane
to the left.
The
Lateral Axis – Pitch
Elevators: The stick
(joy stick) is connected by means of wires or hydraulics to the tail section’s
elevators. By moving the stick, the
pilot can change the position of the elevators.
When the control column is pushed in, the
elevators move down, pitching the tail of the airplane up an the nose down, rolling the airplane down.
When pulling
the control column back makes the elevators move up, pitching the tail of the
airplane down and the nose up, rolling the airplane upwards.
Cars go only left or right, but planes must be
steered up or down as well. A plane has parts on its wings and tail called
control surfaces to help it. These can be demonstrated by use of folded paper gliders
and balsa gliders. Let’s start with an experiment to illustrate how a plane is
controlled.
TAKEOFF
AND CLIMB
After taxiing to the runway, a pre-takeoff checklist
is accomplished. This check is to ensure that all systems are working normally.
When this is completed, the airplane is taxied to the center of the runway and
aligned with it. The throttle is opened fully to start the takeoff run (also
called take off roll). During this takeoff run, the control wheel, or stick, is
usually held in the neutral position, but the rudder pedals are used to keep
the airplane on the runway’s centerline.
As takeoff airspeed is approached, gentle
backpressure on the control wheel raises the elevator, which causes the
airplane’s nose to pitch upward slightly. This lifts the nose wheel off the
runway (see fig. 5-6 ).
Once
the nose wheel is off the runway, the right rudder is applied to counteract the
left-turning tendency, which is present under low airspeed and high-power
flight
conditions. As the airplane lifts dear of the runway, the
pilot varies the pressure on the control wheel. First, pressure is relaxed
slightly to gain airspeed while still in
ground
effect (additional lift provided by compression of air between the airplane’s
wings and the ground). As airspeed increases to the best rate-of-climb
airspeed, back pressure on the control wheel is adjusted to maintain that
airspeed until the first desired altitude is reached. (Best rate-of-climb
airspeed provides the most altitude for a given unit of time.) Climbs to other
and higher altitudes are made at airspeeds determined by the pilot, until the
desired cruising altitude is reached.
Upon reaching cruising altitude, the airplane’s pitch attitude is reduced and the airplane accelerates to cruising speed. The power is reduced and adjusted to maintain the selected cruising speed. Almost simultaneously, the pilot adjusts the elevator and possibly the rudder to keep the airplane at the desired altitude and heading (direction). If the flight is to go to a distant airport, the airplane will be kept in its cruising flight configuration until the destination is near. If the pilot wants only to perform basic flight maneuvers in a practice area, the cruising flight configuration will necessarily be changed rather soon.
LANDING
A good landing begins with a good approach (see figure 5-7 ). Before
the final approach is begun, the pilot performs a landing checklist to ensure
that critical items such as fuel flow, landing gear down, and carburetor heat
on are not forgotten. Flaps are used for most landings because they permit a
lower- approach speed and a steeper angle of descent. This gives the pilot a
better view of the landing area. The airspeed and rate of descent are
stabilized, and the airplane is aligned with the runway centerline as the final
approach is begun. When the airplane descends across the approach end
(threshold) of the runway, power is reduced further (probably to idle). At this
time, the pilot slows the rate of descent and airspeed by progressively
applying more back pressure to the control wheel. The airplane is kept aligned
with the center of the runway mainly by use of the rudder.
Continuing backpressure on the control wheel, as the airplane enters ground effect and gets closer and closer to the runway, further slows its forward speed and rate of descent. The pilot’s objective is to keep the airplane safely flying just a few inches above the runway’s surface until it loses flying speed. In this condition, the airplane’s main wheels will either “squeak on” or strike the runway with a gentle bump. With the wheels of the main landing gear firmly on the runway, the pilot applies more and more backpressure on the control wheel. This holds the airplane in a nose-high attitude, which keeps the nose wheel from touching the runway until forward speed is much slower. The purpose here is to avoid overstressing and damaging the nose gear when the nosewheel touches down on the runway. The landing is a transition from flying to taxiing. It demands more judgment and technique than any other maneuver. More accidents occur during the landing phase than any other phase of flying. Variables such as wind shear and up-and-down draft add to the problem of landing. Good pilots can be easily recognized. They land smoothly on the main wheels in the center of the runway and maintain positive directional control as the airplane slows to taxiing speed.
Certificates
Recreational Pilot Certificate
With
a Recreational Pilot Certificate, a person is qualified to act as
pilot-in-command of a single-engine aircraft carrying 1 passenger. A person with Recreational Pilot Certificate
may only fly under day visual fight rules (VFR). In other words, the pilot may fly only in the
daytime with good weather conditions. A
Recreational Pilot may not receive compensation (can’t get paid or receive
gifts) for his/her services. A
Recreational pilot must meet currency requirements and is limited to a 50
nautical mile range.
The
FAA requires a minimum of 30 hours of logged flight training to obtain the
certificate.
Here’s
some of the requirements you need to be eligible according to 14CFR 61.96 (14CFR is what is commonly known as the FARs):
- At least 17 years of age;
- Read, speak and understand
English;
- Hold at least a third class
medical;
- Receive an endorsement from
an instructor who gave or reviewed the applicants ground training and
certified that the student is prepared for the knowledge test;
- Receive an endorsement from
an instructor who gave the applicant’s flight training and certified that
the student is prepared for the knowledge test;
- Pass a written exam
(knowledge test);
- Meet the aeronautical
experience requirements;
- Pass an oral and flight test.
With a Private Pilot Certificate, you can act as
pilot-in-command of an aircraft carrying passengers and baggage. A private
pilot (without an instrument rating) may only fly under visual fight rules
(VFR). In other words, the private pilot
may fly during the day or night, but still only in good weather
conditions. The private pilot may not
receive compensation for his/her services either (you must have at least a
Commercial Pilot Certificate to get paid to fly). You will still have some currency
requirements as a private pilot, but you are not limited to any flight radius.
The
FAA requires a minimum of 40 hours (Part 61-Regular flight school) or 35 hours
(Part 141-Formal flight school) of logged flight training.
Here’s
some of the requirements you need to be eligible according to 14CFR 61.103:
- 17 years of age for airplane
or helicopter certificate. You may
solo an airplane, or get a glider or balloon certificate at 16;
- Read, speak, understand, and
write English;
- Receive an endorsement from
an instructor who gave or reviewed the applicants ground training and certified
that the student is prepared for the knowledge test;
- Pass a knowledge test;
- Receive an endorsement from
an instructor who conducted the applicants training and certified the
applicant is prepared for the practical test;
- Meet the aeronautical experience
requirements.
- Pass an oral and flight test.
With an instrument rating, a pilot can fly the aircraft by
solely using the flight instruments within the aircraft. When flying using
visual flight references (VFR), the pilot uses objects outside the aircraft,
such as the horizon, to control and maneuver the aircraft. When flying using
instrument flight references (IFR), the pilot uses the instruments within the
aircraft to fly. In order to fly IFR a pilot must earn an instrument rating.
All
professional pilots are instrument rated.
With an Instrument Rating, the pilot doesn’t have to depend on clear
flying days to enjoy a flight. Getting
an instrument rating also makes a pilot a safer, more skillful flier.
The FAA requires a minimum of 125 hours (Part 61-Regular flight school) of
logged flight time. At least 50 hours of flight time must be cross-country time
(not a local flight).
Here’s
some of the requirements you need to be eligible according to 14CFR 61.65:
- Hold at least a private pilot
certificate (with appropriate aircraft rating);
- Read, speak, understand, and
write English;
- Receive and log ground
training from an instructor or home-study course on the aeronautical knowledge
areas required;
- Receive an endorsement from
an instructor who gave or reviewed the applicants ground training and
certified that the student is prepared for the knowledge test;
- Receive and log training
in the areas of operation required from an instructor in an aircraft,
simulator, or training device appropriate to the rating sought
(helicopter, airplane etc.);
- Receive an endorsement from
an instructor who conducted the applicant’s training and certified the
applicant is prepared for the practical test;
- Pass a knowledge test;
- Pass an oral and flight test
I won’t try to list all the job opportunities there
are in aviation. They range from
manufacturing to dispatching. As a
pilot, there are careers available as a flight instructor, airline pilot,
military pilot, and air ambulance pilot, among many others. If you’d like to see a very comprehensive
site with oodles of links to aviation check this out: http://smilinjack.com/
A great way to get a flight
in an airplane is to try a flight with your local Experimental Aircraft
Association. They have a program called
Young Eagles, call 1-877-806-8902, and talk to one of their folks about a flight opportunity near you. Or take a look at this link: http://www.youngeagles.org/
As
a budding airman, you will want to get as close as you can to real planes and
real airports. You will want to see airplanes and fliers in action. That’s just
fine. You will be welcome to visit almost any airport and any Federal Aviation
Administration facility. Be sure to call ahead to make an appointment,
especially if you are coming with your Scout troop.
When you visit an
airport, don’t forget that you are there as a guest. Remember that the people
working there have jobs to do. They will be glad to answer your questions, but
bear in mind that the business of the airport must come ahead of your
curiosity.
There’s another thing
to remember when you’re at an airport. This is that there are special dangers
around planes and landing fields that you must watch out for.
Here
are some of the rules of safety:
If you are going to take a flight:
·
Obey all instructions of the pilot and
crew.
·
Fasten your seat belt securely for takeoffs and landings and when instructed to do so.
If
you are walking around planes or hangars:
·
Keep well away from propellers and
helicopter tail rotors, even if they are not turning. Always walk behind an airplane, in front of
a helicopter.
·
Keep away from jet intakes and exhausts.
·
Heed all warning signs.
As an airport visitor:
·
Keep off the flying field.
·
Stay out of operations rooms and control towers unless you are being
conducted by a guide.
I’d recommend visiting a
local small airfield. Talk with the
local Fixed Base Operator (FBO), they’re the folks that sell fuel and
supplies. Most are more than willing to
help out a Scout. Smilin’
Jack has an extensive list of larger airports on his site: http://smilinjack.com/airports.htm
A good place to start is by
checking out the FAA’s web site at: http://faa.gov/
Visit an Aviation Museum or Airshow
Don’t
know of a museum in your area? Try this link: http://aeroweb.brooklyn.cuny.edu/museums/museums.htm
This
site has practically all the airshows being held
worldwide: http://www.airshows.com/
Aircraft Instruments
Airspeed indicator This
displays the speed at which the airplane is moving through the air. The airspeed indicator is one of the
pressure instruments using the pitot-static
system. Most airspeed indicators use a
combination of impact air pressure (from the pitot
tube) and static air pressure (from static ports) to give a correct
reading. The airspeed indicator in the
figure is indicating an airspeed of 135 knots (nautical miles per hour). Most modern aircraft use knots to measure speed. A nautical mile is 6,076 feet. Your family
car uses statute miles per hour. A
statute mile equals 5,280 feet.
Attitude indicator This is
also called the Artificial Horizon. This
displays the attitude of the airplane (nose up, nose down, wings banked) in
relation to the horizon. The attitude
indicator is a gyroscopic instrument; that means it uses a gyroscope to
maintain its relative position. In most
smaller, private aircraft, the attitude indicator’s gyroscope is spun by high
speed air provided by a suction (vacuum) pump mounted on the aircraft
engine. The attitude indicator in the
figure is indicating level flight (nose and wings are level in relation to the
horizon).
Altimeter This displays the altitude of
the airplane above mean sea level (MSL) when properly adjusted to the current
pressure setting. The altimeter uses
static air pressure provided by the pitot-static
system’s static ports. The little knob
you see adjusts the altimeter to the local barometric pressure to provide an
accurate reading. The pilot simply
adjusts the altimeter until the correct barometric pressure is set in the
little window (the Kollsman window). The altimeter in the figure is indicating an
altitude of 14,500 ft. MSL.
Turn and Bank Indicator This is also
known as the Turn Coordinator, or sometimes Turn and Slip Indicator. The Turn and Bank indicator displays the rate
at which a turn is being made. The
“Turn” portion of the indicator is a gyroscopic instrument. If you have a vacuum driven attitude
indicator, you would want to have this important back-up instrument use another
power source (usually the plane’s electrical system). The miniature airplane banks in the direction
of the turn. At the bottom of the instrument is a ball in a glass tube called
an inclinometer. The inclinometer uses
gravity and inertia to indicate aircraft movements called slips and skids. The inclinometer indicates whether the
airplane is in coordinated flight (centered) or uncoordinated flight. The turn
coordinator in the figure is indicating wings level and coordinated flight.
Heading indicator This
displays the heading (direction) the airplane is flying. This is also a gyroscopic instrument. The
indicator is not a compass so it must be set to agree with the aircraft’s
magnetic compass. Compasses are
notoriously unreliable when an aircraft turns, changes pitch, or airspeed. For this reason, pilots use a system that
maintains accuracy in all phases of flight—a gyroscopically driven
indicator. In most smaller, private
aircraft, the heading indicator’s gyroscope is also spun by high speed air provided
by a suction (vacuum) pump mounted on the aircraft engine. The heading
indicator in the figure is indicating a heading of north.
Vertical speed indicator Also known
as the VSI or VVI for military pilots.
The VSI uses static pressure from the pitot-static
system to give its readings. The VSI
displays whether the airplane is in level flight, climbing, or descending. The
rate of climb or descent is indicated in hundreds of feet per minute. The VSI
in the figure indicates level flight.
Compass This is pretty much just like the compass you use in orienteering. Remember it is only reliable in level, un-accelerated flight. When you put a compass in an aircraft you must also take care to compensate for any metals in the aircraft which may cause deviations.
COMM/NAV Radios Pictured is a combination radio which allows the pilot to communicate with Air Traffic Control and use GPS to navigate. This example even uses a virtual moving map to display the aircraft position.
This
is a combination VOR navigation and VHF communication radio. Both this and the GPS/COM radio pictured
above can be linked to another instrument used to provide guidance for the
airplane to fly an instrument approach and enroute
navigation.
This
instrument provides guidance by setting the desired course and flying the
vertical needle for course guidance and the horizontal needle for glidepath (on a precision approach)
Tachometer This is a digital tachometer or tach. Just like one you may find in your car, pilots use it to keep track on how fast the engine is revving.
Oil Pressure and
Oil Temperature Gauges
These to instruments are
important to have on your powered aircraft.
They provide an indication of lubrication and temperature of your
engine. Any change from normal
indications gives the pilot an advance notice to ensure the engine continues to
operate normally.
Here’s an image of an airplane instrument panel you can use
to help with your poster design. The
picture comes from:
http://www.firstflight.com/fsp.html
An excellent guide to
preflight an airplane can be found at this link: http://www.firstflight.com/pre.html
Check out the web site for the
Safety in Building Model
Airplanes
One
of the best ways for you to learn about airplanes and the principles of flying
is to build model planes. And, in fact, you may have to build at least one to
earn the Aviation merit badge.
·
Be careful when using a razor blade or
knife to cut materials.
·
Do not inhale fumes from airplane cement
or airplane dope. This can be fatal.
·
Keep all materials and tools away from
small children.
Safety
in Flying Models
There is one common sense rule of safety when you and your friends are flying model planes: Stay out of
their way! Even a light, balsa‑wood model powered by a rubber band might
hurt if it hit you. Some big models with one or more gas engines may weigh as
much as 15 pounds. And there are model planes that travel more than 150 miles
an hour. It doesn't take much imagination to know what would happen if you were
hit by one.
Another good rule to remember is:
Treat all wires on poles as if they could kill you. If your model gets caught
in powerlines, leave it there until the wind blows it
down or call the service company. Don't try to retrieve it by yourself.
The Academy of Model Aerobauties, which is a nationwide organization of model
plane build‑ has a number of safety rules for its competitions. Here are
the most important ones; you should keep them in mind whenever you are near
flying models whether you're at a competition or not:
·
For Free‑Flight Models
(not controlled from the ground) ‑spectators should stay upwind at least
75 feet from the takeoff area.
·
For U‑Control Models
(pilot flies the model by operating its control surfaces through a long line) ‑spectators
must stay at least 75 feet from the flying circle unless protected by a screen.
·
For Radio‑Control Models
the AMA has a safety inspection for all models before starting a meet. Any plane
allowed to fly over spectators is disqualified. Knife‑edge wings are not
permitted, and models must have rounded prop spinners or safety covers over
propeller shafts.
Whether you ever enter a model in
competition or not, these rules should suggest to you this guide: Don't
fly your model in any direction where it might hit someone.
The Phonetic Alphabet
This Merit Badge guide was edited by:
SM Troop 509, (http://troop509.org)
I used to be a Buffalo
Time to pat myself on the back:
About me & why I did this: I
love to fly. I am a retired USAF pilot. I went to pilot training at the now-closed
Williams Air Force Base, near Phoenix, Arizona.
In the Air Force I flew the T-37, T-38, A-37B, AC-130H, AC-130U,
C-130E/H, C-12, and C-47. After I
retired from the Air Force, I completed my Airplane ratings by earning an
Airline Transport Pilot (ATP) Certificate in single and multi-engine land
airplanes. I also have an ATP in single
and multi-engine seaplanes. I am a
Certificated Flight Instructor (CFI), Multi-Engine Instructor (MEI), and
Instrument Instructor (CFII) in airplanes.
I now work
as an Instructor Pilot with Lockheed Martin at the 19th Special
Operations Squadron, where I teach AC-130H Spectre
Gunship and AC-130U Spooky Gunship Aircrews.
If you can’t find a pilot to interview for your requirements, contact me and I’ll do an interview by
phone or NetMeeting.
This guide may be distributed freely
and I claim no copyright since all material was derived from various
educational sites on the internet. Enjoy
and pass on the torch.
YIS,
B2