Re: Why did the Wright Flyer have propellers on the backof the plane?

Greetings Barbara:

Yours is a super question.
Today most propeller driven aircraft, but not all, have propellers that
pull the aircraft. However, there are a number of famous airplanes that have
also used pusher propellers. The giant B-36 bomber had six engines with six
pusher propellers. You can see several pictures of the B-36 in flight at the
following web site:

http://www.jacobsensb-36hangar.bigstep.com/

More recently the Cessna company has manufactured a small twin engine aircraft,
the Model 377 Super Skymaster, with one engine with a puller propeller in front
of the cabin and one engine with a pusher propeller in back of the cabin. You
can see pictures of this aircraft at the following web site:

http://www.marchfield.org/o2b.htm

There have been several new aircraft designs that also place the control
surfaces in the front and use pusher propellers in the rear. These aircraft can
be seen on the following web sites, including the Voyager that flew around
the world without refueling. Voyager had push and pull propellers similar to
the Cessna Super Skymaster:

http://www.nasm. edu/nasm/aero/aircraft/rutanvoy.htm

http://www.rut anaircraft.com/htmlpages/airplanes.html

Each of these aircraft used a pusher propeller for a different reason. There are
several reasons why the Wright brothers used a single engine with two pusher
propellers on the 1903 Wright Flyer (WF03). To understand these reasons it would
be helpful for you to look at the animated picture of the WF03 with rotating
propellers at the following NASA Glenn Research Center web site:

http://wright.nasa.go v/airplane/propeller.html

Two important inventions that enabled the Wright brothers to be the first to
succeed in flying a powered aircraft were the design of the wing and control
system and the design of the propulsion system. For the propulsion system they
used a small gasoline powered engine driving two counter rotating, 8 foot long,
thin propellers that rotated at about 350 revolutions per minute. That is about
6 revolutions each second! At that time, other people tying to fly were using
low speed, thick bladed propellers, much like the blades of a wind mill.
The Wright brothers designs were much more efficient at providing thrust and
lift for their aircraft. The Thrust Force is the forward pulling force
that drives an aircraft forward through the air. The thrust force must overcome
the air resistance which pulls backward on the aircraft. This backward force
is called the Drag Force. Notice how large the WF03 propellers are
compared to the size of the pilot and the distance between the wings. Those
sharp edged, very large, high speed, rotating propellers were very dangerous
and they were very difficult and time consuming to make.

The 1903 Wright Flyer did not have wheels, they would have been to heavy,
would increase the Drag Force and would not work in the sand at Kitty Hawk.
The WF03 used skids in place of wheels. Wheels would come later when more
powerful engines to overcome drag would be developed. The WF03 and it's
predecessors crashed several times during the years of testing at Kitty Hawk
and when they crashed the aircraft would land nose first and the pilot would
be pulled forward with great force. If the pilot's restraints failed during a
crash, he would be catapulted forward through the propellers and would have been
chopped up like meat in a large grinder! Even if that did not happen, nose
mounted propellers would hit the ground first a be smashed to pieces! By
placing the propellers behind the wings, the pilot's forward visibility was
improved and it would be safer for him in a crash. Also, in
the rear location the expensive propellers were protected from hitting the ground.
You can see these advantages on the NASA drawings.

Another reason for the location of the propellers was for balancing the WF03.
An aircraft must be perfectly balanced about the center of the wing where the
Lift Force of the wing pulls upward on the aircraft against the downward
pulling Gravity Force from the weight of the aircraft. Imagine the WF03
is a Teeter-Totter. If we make believe that the rod on which the Teeter-Totter
rotates is the center of the WF03's wing, the Teeter-Totter riders must be
perfectly balanced to have them both keep off the ground at the same time. If
one rider is slightly heavier that the other, that end of the Teeter- Totter
will hit the ground first.

The propellers and the drive chains are placed in the back of the WF03's wings,
to perfectly balance the small control wings and skids that stick out in the
very front of the aircraft. Also, an aircraft must be balanced from side to
side to avold tipping the wing tips into the ground. You can see on the NASA
drawings, the heavy pilot and the heavy engine are placed side by side
over the center of the wings. The engine on one side balances the pilot on the
other side, keeping the wings from tipping. At the same time they are also placed
forward and back to keep the nose and the tail balanced. Note that the WF03
propellers also rotate in opposite directions so that they do not tip the
aircraft wings.

In later years, the location of the control surfaces and the propulsion system
were reversed with the control surfaces being placed in the rear of the aircraft,
perfectly balanced by the engine and propellers in the front of the aircraft.
This also enabled room for more passengers to ride within the longer tail boom
of more modern aircraft while still keeping the aircraft balanced.

ANSWERS

Why were the propellers placed in the rear of the 1903 Wright Flyer?

The propellers were placed in the rear of the 1903 Wright Flyer to:

• To increase pilot safety,
  
• For better pilot visibility,
  
• To protect the expensive propellers from being damaged during crashes,
  
• To balance with the control surfaces and skids placed far front of the aircraft.