Field Trip 4: Visit to the National Museum of the US Air Force
Host & Coordinator: Dr. Kelly Cohen, Professor of Aerospace Engineering & Engineering Mechanics
Date: Wednesday, July 23rd 2014
Time: 12:00pm – 5:00pm
Venue: National Museum of the US Air Force, 1100 Spaatz St, Dayton, OH 45431
Prepared by:
Adam Katterheinrich, University of Cincinnati, Cincinnati, OH
Nicholas J. Nielsen, University of Cincinnati, Cincinnati, OH
Tyler Parcell, University of Cincinnati, Cincinnati, OH
REU Participants for Project #4: “Emulating Human Reasoning through Enhanced Decision Making”
Dr. Kelly Cohen took the REU students to the National Museum of the US Air Force for a tour
focusing on the history of flight and the development of control theory from the Wright brothers to
modern day (see Figure 1). The plan was to take a guided tour and our official tour guide was a
gentleman by the name of Mr. Dan Stayer, a retired USAF official. The tour began with a brief
introduction to flight mechanics and control systems of the 1909 Wright flyer. Mr. Strayer pointed out
that while the control systems on the 1909 Wright Flyer perform essentially the same tasks to those in
modern aircraft; i.e. static and dynamic stability as well as the ability to perform controlled maneuvers;
they are quite different in overall design from one another.
Figure 1: REU Project 4 Team with Dr. Cohen
On the Wright Flyer, shown in Figure 2, there are cables that run from the control lever to the
edges of the wing surfaces through a system of pulleys. This system of cables and pulleys actually warp
or morph the wing directly changing the shape of the airfoil on the outer section of the wing. This
warping action is performed in opposing directions on each wing causing one wing to loose lift while the
other wing gains lift. This difference in lift creates a moment about the roll axis resulting in a rolling
motion toward the wing with less lift. There are also cables running to the elevator/horizontal stabilizer
and the rudder/vertical stabilizer. These cables enable the entire control surface to pivot in the desired
direction. Control surfaces such as these are known as flying control surfaces. Flying control surfaces
can be very sensitive therefore; they were quickly substituted for a fixed surface approach to flight
control that is still used on modern aircraft today.
Figure 2: The Wright Flyer
From the Wright Flier the REU group moved on to WWI era aircraft. These airplanes used a control
method that is much more familiar, compared to modern aircraft. While the control systems still
consisted of wires and pulleys attached to levers and control surfaces the method of control actually
changed. The control surfaces such as ailerons, elevator, and rudder where rigid control surfaces
attached to wings or stabilizers by hinges and actuated by the cables attached to lever arms on the
hinged surfaces. This Paradigm of control persisted through WWII were we see one of the world’s first
Unmanned Aerial Vehicles in the form of the V-1 Buzz Bomb (see Figure 3). This was essentially an
eighteen hundred pound bomb with wings, powered by a pulse jet engine and a pre-programmed
autopilot.
Figure 3: The first Unmanned Aerial Vehicle - The V-1 Buzz Bomb
As time progressed, cables and levers were replaced with hydraulics and actuators. Eventually,
control systems progressed to the point where the pilot no longer had a direct mechanical connection to
the aircraft. We now see in today’s modern aircraft a system known as Fly by Wire. In a Fly by Wire
System Aircraft (see Figure 4), the pilot provides a stick input that is read by an onboard computer. The
computer then interprets this signal and supplies a command to the actuators that in turn move the
associated control surfaces. This method of control provides a very precise and smooth response by the
aircraft. The Fly by Wire system also allows the onboard computer help the pilot stabilize the aircraft
without the pilots input. This system also reduces the physical exertion that was required by mechanical
control systems during high performance maneuvers.
Figure 4: The Fly by Wire system Aircraft
In recent years, a new method of Control has arisen. The advent of the modern UAV has
ushered in an era of intelligent aircraft when compared to their predecessor the V-1 buzz Bomb. The
RQ-4 Global Hawk and the MQ-9 Reaper (see Figure 5) are fully controllable via satellite uplink and
capable of being sent on multifaceted missions for extended periods. This contrast between the V-1,
which was essentially an intelligent bomb and the modern UAV, shows an immense leap in control
systems technology.
Figure 5: MQ-9 Reaper UAV
This trip through time as the REU students progressed through the museum highlights the
breakthroughs and innovations that humans have made in the area of flight from its inception until
today where we have the most advanced and intelligent aircraft the world has ever known. With all the
advancements in aviation and as far as we have come from the Wright brother airplane flown in 1903
near Kitty Hawk, North Carolina, it is interesting to note that in recent years some of the methods such
as flying control surfaces and wing morphing have been a re-emerging as potential concepts in control
using smart structures and materials