AIAA_StudentUndergraduateTeam_SilverBird

American Institute of Aeronautics and Astronautics
1
Simulation and Design Modification of the Wright B Flyer
Inc. Silver Bird Replica
University of Dayton Innovation Center
Domenic Miccinilli1
University of Dayton, Dayton, Ohio, 45469
Matt Pulfer2
Denton Sagerman3
Alex Watt4
and
Seth Wieging5
I. History
The Wright Brothers successfully built the first practical flying aircraft back in 1905, the Wright Flyer. While
the aircraft was in fact overall a success, improvements were made to the design to improve stability and overall
functionality of the aircraft. The result was the Wright Model B, which was first piloted in 1911 and was the first
plane the Wright Brothers produced in quantity. Today, Wright B Flyer Incorporated, a company located just outside
of Dayton, Ohio, specializes in Wright Model B replicas. In their hangar, they currently house a fully functional
replica known as the Brown Bird, and a non-flying replica referred to as the Valentine Flyer.
In 2007, Wright B Flyer Inc. manufactured another flying replica known as the Silver Bird. The aircraft was smaller,
lighter, and was designed to be more transportable than the Brown Bird to facilitate travel to various airshows. After
a few test flights, the aircraft was awarded an FAA airworthiness certification back in the Fall of 2010.
Unfortunately, in June 2011, after about 20 hours of flight time, the aircraft was lost in a crash during a routine test
flight. Upon investigation, it was deduced that a welding malfunction caused a failure in one of the propeller shafts,
rendering one of the props essentially useless. The tragic occurrence resulted in the death of two pilots. In the time
following the crash, Wright B Flyer Inc. has commissioned another Silver Bird model to be designed and produced.
Some of the goals of the new model include improved safety, better performance, and heightened transportability. In
order to improve the safety, and performance of the aircraft, Wright B Flyer Inc. come to the University of Dayton
to receive assistance in modeling the design into the school’s MERLIN Flight Simulator. This will allow the design
to be easily evaluated, as well as any changes to the design. Back in the Fall of 2014, another team of University of
Dayton students took on a similar project for the Brown Bird model. This team successfully modeled the aircraft
into the flight simulator, thus demonstrating the capabilities of the sim. Our design team of students has since been
1
Undergraduate Student, University of Dayton, 300 College Park Dayton, Ohio, Member Number: 545069.
2
3
4
5

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at work evaluating the design, and implementing it into the simulator, whilst receiving input from various test pilots
and mentors.
II. Preliminary Design Considerations
A. Airfoil Analysis
Prior to modeling the Silver Bird into the flight simulator, the team determined that an airfoil analysis was
necessary. The Silver Bird wings utilize a specially designed USA 35b airfoil, however the team ran into trouble
analyzing the airfoil using Airfoil Tools (XFOIL) and implementing the airfoil into the simulator. After consulting a
mentor, it was determined an analysis should be done to find a similar airfoil to use instead of the USA 35b.
Multiple airfoils were investigated and analyzed in XFOIL until the team decided to go with a NACA 4412. A
comparison of the two can be seen below in Figure 1. The two have a similar thickness, with the 35b having slightly
more camber. Nonetheless, the team decided to model the NACA 4412 into the simulator rather than the USA 35b.
Figure 1: Airfoil Geometry Comparison
B. CG and mass breakdown
To assist in analysis, Wright B Flyer Inc. supplied the team with a center of gravity mass breakdown of each
component on the aircraft (See Figure 2). In order to calculate the x-location of the CG, x-locations of each
component, along with their corresponding weights were used. This allowed moments to be calculated, and
ultimately an overall CG location was determined using the total weight and moment3
. At full payload, full fuel, the
CG sits at approximately 28% of the mean aerodynamic chord. Assuming an aerodynamic center of 25% MAC, this
implies that the aircraft is inherently slightly unstable. The plane also incorporates a 145 lb ballast located at the
front of the aircraft. Without the ballast, the CG is located at approximately 38% MAC, which leads to a very
unstable aircraft. For this reason, the ballast is a necessity. In order to further understand the CG location and mass
breakdown, Figure 3 was generated to show the CG envelope under various fuel and payload conditions.

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Figure 2: Mass Breakdown
Figure 3: C.G. Location X-direction
III. Simulator Background
The simulator used for this project is a Merlin Flight Simulator, shown in Figure 4, which is the only one of its kind
here in the United States. What makes the simulator unique is that it was designed for academic purposes rather than
strictly flight testing purposes. A typical flight simulator is tailored to model a few specific planes that are similar in
class, whereas the Merlin simulator allows a user to define the exact type of plane they want to model, and then test
it for engineering purposes.

4
Figure 4: Domenic Miccinilli (Team Member) flying Silver Bird in Simulator
A. Interface
How a plane is loaded into the simulator is through Merlin’s design software Excalibur II. This software consists of
different tabs or spreadsheets that allow for the input of different parameters for a plane. The tabs are divided into
sections that concern the geometry, center of gravities, propulsion, and drag on an aircraft. When modeling the
wing, the user is required to load a specific airfoil into Excalibur. A wing can be modeled as multiple panels
allowing the user to choose what airfoil to use for each panel. Panels can be modeled as either horizontal or vertical
and can be modeled as an aileron, elevator, or stabilator. When modeling deflecting surfaces, the user must put in
the range of deflection for the surface as well as respective CL and CD increments for various deflection angles. Once
all necessary data for a plane is loaded into Excalibur, the user is then able take a seat in the simulator and fly the
plane.
Inside the cockpit is a throttle on the left hand side of the user that can be modeled for single and double engine
aircraft. There is a joystick on the right hand side of the user allowing for pitch and roll of the aircraft. At the user’s
feet are two foot pedals that enable the plane to yaw. A heads up display also provides feedback on varying flying
parameters such as rate of climb, altitude, airspeed, and trim.
B. Outputs and Capabilities
The output of the simulator really depends on what type of plane is being modeled. The simulator is capable of
modeling various types of planes such as bi-planes, single and double engine planes, and even Vertical Takeoff and
Landing (VTOL) aircraft. Other capabilities of the simulator are modeling a plane in different environments. Once a
plane has been modeling it can then be simulated at any given altitude in which the user can even choose to add or
reduce turbulence and or crosswinds for the simulation. Along with this, users can also model engine out scenarios
to test the controllability of a plane in the event of a malfunction.
C. Limitations1
Some of the limitations of the simulator is that it cannot model an offset wing. When modeling a wing in the
simulator, a user has to model half of the wing which the simulator mirrors over to the other side. This makes it
impossible to account for a wing that is not centered along the fuselage of the plane. Another limitation for the
simulator is when modeling a prop driven plane, the user does not have input on the direction the propellers rotate.
These limitations are taken into account when modeling the aircraft and are considered by the test pilots when flying
a plane that may not be an exact representation of the real aircraft.

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IV. Silver Bird Version I
A. Inputs
The Silver Bird design is very unique, in that it is a biplane, with essentially no fuselage, and runs off of one engine
which powers two propellers. In order to successfully implement the design into the MERLIN Flight simulator, the
team first began by extracting crucial dimensions and aerodynamic locations of the aircraft1
. This was completed
with the use of a 3D Solidworks CAD model, as well as three view drawings provided by Wright B Flyer Inc. The
upper and lower wing, as well as the horizontal tail were modeled as horizontal panels, with aerodynamic center
locations referenced from a datum at the front of the plane. Figure 6 shows the H panels, as well as the datum
location. As seen, only half of the span was programmed into the simulator. This is because the simulator mirrors
each panel to create the whole surface. This was actually a problem for this aircraft because it is not completely
symmetric (as discussed in the following section). The Silver Bird has two blinkers at the front of the aircraft which
were modeled as vertical panels along with the two rudders. The blinkers were modeled as two flat, triangular plates.
The rudders were modeled using a symmetric NACA 0006 airfoil. Figure 5 shows the vertical panels as well as the
datum again.
Figure 5: Silver Bird CAD Side-view
Figure 6: Silver Bird CAD Top-view
Airfoil selection was trivial for both the horizontal tail, and vertical tail, however the wings required some extra
research. The NACA 0006 was easily modeled into the flight simulator for the tail, and is the actual airfoil that the

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Silver Bird will implement. As discussed earlier, the NACA 4412 was implemented for the wings. This was done by
extracting XFOIL data and importing the data into the simulator’s user interface. The geometry as well as the Cl Cd
and Cm increments were programmed into the simulator to effectively capture the airfoil characteristics.
As mentioned, data was provided with regards to mass and center of gravity information (See Figure 2 in the
preliminary design considerations). The coordinates of the CG, with respect to the datum, were input into the
simulator. The empty mass as well as the mass and location of each of the two pilots was also modeled into the
simulator. The Silver Bird is expected to house fuel in the lower wing, and therefore, a mass and location of the fuel
was set to be in the same spot as the lower wing along the z-axis.
As far as propulsion is concerned, the Silver Bird utilizes a single 206 hp engine, located at the center of the aircraft,
which drives two propellers through a system of chains. The Silver Bird’s props are located aft of the wing, as seen
in Figure 5 and Figure 6. Unfortunately, due to the limitations of the simulator, the team could not model only one
engine and capture both propellers. In order to accurately model the thrust from each propeller, it was treated as a
twin engine aircraft, where half the horsepower was modeled at the location of each propeller.
The undercarriage of the aircraft was modeled in order to accurately account for gear drag, and allow the aircraft to
taxi on the runway. Again, the coordinates of both nose gears and main gears were modeled with respect to the
datum axis system shown above.
The fuselage was perhaps the most difficult component on the aircraft to model correctly. Again, this is simply due
to the fact that this plane basically has no fuselage. The flight simulator allows the user to input Cd increments for
certain angles of attack and side slip angles. These increments were adjusted in order to accurately capture the flight
characteristics of the aircraft. Unfortunately, there was little documentation on how to determine these increments,
so capturing the accurate drag was somewhat a process of trial and error.
Based on the inputs for the Silver Bird Version 1, the following constraint diagram was made in order to evaluate
valid design space and where the current model sits within this space (indicated with the blue circle). The constraints
on the design space stem from the equations given in Daniel Raymer’s Aircraft Design: A Conceptual Approach2
text for general aviation aircraft. This allowed the team to estimate how changes to the aircraft affected the bounds
of the design space and which performance criteria are limiting the design the most.
Figure 7: Constraint Diagram

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B. Problem encountered with Simulator Interface
There were a few issues that occurred while inputting the Silver Bird data into the Flight Simulator. The first, and
possibly the most important in regards to the accuracy of the model, is that the Flight Simulator cannot accurately
model the non-symmetric wings of the Silver Bird. The Flight Simulator takes the inputs for only one of the wings
and then copies it over to the other side of the airplane making the wings symmetric. The Silver Bird, as described in
a previous section, has non-symmetric wings where one side of the aircraft has a wing longer than the other.
Therefore, the difference in span of each wing cannot be modeled accurately due to the fact the Flight Simulator can
only model the left or right wing and copy it over. To solve this problem, the team decided to move the datum point
of the aircraft over to where the wings will be symmetric and model the left or right wing according.
The second issue the team had to debug was how to model an “engine out” simulation in the Flight Simulator. This
is easy to do with many modern aircraft because most twin engine aircraft have equal engines on both sides and
therefore can easily model the two propulsion forces. The Silver Bird, however, has two propellers but only one
engine creating power. Modeling where the propulsion was coming from was not the problem, but the team had a
problem modeling how to model the power with an engine out simulation.
Another issue the team discovered while inputting the data into the Fight Simulator is how the fuselage drag is
modeled in Excalibur II. At first glance, the team was confused due to the fact the drag values present did not match
any realistic drag coefficients numbers. Looking through the Flight Simulator manual there was no solution to the
issue at hand. The team decided to take advice from the previous team who modeled the Brown Bird in the Flight
Simulator. They stated that there numbers were based off test pilots comments on Rate of Climb and takeoff speeds.
Comments made by test pilots greatly influenced the drag on the fuselage.
C. Test Pilot Feedback
In order to validate the Silver Bird model, the team had two meetings with experimental test pilots, Rich Stepler and
Tom Walters in which various flight tests were conducted. These two test pilots are among a select group five living
pilots who have flown the Silver Bird before its crash, having logged approximately 15 of the 24.1 total hours
combined. The tests conducted along with the resulting plots were extracted from the flight simulator data log output
and interpreted through a self-assembled MATLAB code. A set of four flight tests was created to allow for
standardized evaluation of the Silver Bird between test pilots.
Test #1: Takeoff
This test allowed for the takeoff distance of approximately 700 feet to be observed, compared to the value of 800
feet from actual Silver Bird data, along with the corresponding rate of climb, stick input and elevator deflection from
ground to approximately 150 feet, as seen in Figure 8. This test was completed with full thrust and neutral stick
position to takeoff at 50 knots.

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Figure 8: Takeoff Flight Data
Test #2: Steady level full stick back deflection to evaluate rate of climb
The elevator deflection, which from the model ranged from 19 to -23 degrees, and maximum rate of climb of 550
ft/min was experienced with full stick back deflection and full power (Figure 9). The short period damping with full
negative stick deflection occurred during a 20 second period peak to peak. This indicated that the aircraft was too
well damped and could have been a result of the trim setting or center of gravity location with respect to the actual
Silver Bird. The elevator deflection as a function of time, in the upper right hand corner of Figure 9, was used to
verify the elevator deflection during the maneuver to achieve the appropriate rate of climb.
Figure 9: Pitch Singlet Flight Data

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Test #3: Roll Rate
Performed at 55 knots and at an altitude of 400 feet, a 20 degree bank to bank turn was completed which resulted in
a 20 deg/sec roll rate compared to the actual Silver Bird which had a roll rate of 15 deg/sec. This discrepancy is
attributed to the increased aileron effectiveness of the model, when compared to the actual aircraft as well as the
stick input sensitivity compared to the handlings of actual Silver Bird.
Test #4: Steady level sideslip and release
In order to evaluate the roll yaw coupling, a full rudder deflection (beta) was compensated for with stick deflection
to maintain steady heading. Then the rudder was released and the time and number of oscillations until the aircraft
was fully damped was captured. As seen below in Figure 10 the rudder (beta) deflection and roll angle can be seen
in terms of headings angle, which was useful in evaluating the beta sideslip at 55 knots and 500 feet.
Figure 10: Steady Level Side-slip Flight Data
The following depicts the test pilot feedback along with the resulting changes made to the Silver Bird:
Rich Stepler’s Comments:
• Too much stick down input to achieve steady level flight → center of gravity was moved forward by 0.1
meters. This was justified from sensitivity of the Silver Bird to pilots weights and ability to change this by
minimal geometry manipulation.
• Rate of climb too low → fuselage drag was decreased in order to achieve rate of climb and cruise speed from
limited flight test data from actual Silver Bird flight data.
Tom Walters’ Comments:
• Roll response too high → decreased lift increments of the ailerons along with percent stick input per percent
aileron deflection
• Lack of elevator flare in power off steady dive (55 knots) → increase elevator maximum positive deflection
by 1 degree to account for flight simulators inability to account for propeller downwash which would
effectively increase the elevator’s effectiveness. Also elevator lift increment at max deflection was slightly
increased.
• Throttle response too slow → throttle lapse rate was increased
• Trim response negligible → increased alpha trim range in order to be able to trim to steady level flight at
cruise speed and altitude

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V. Future Plans
The aircraft will need to be further evaluated to incorporate design changes that could change the performance of the
aircraft or improve the sensitivity of the controls. Evaluating geometry changes was a design requirement specified
by Wright B Flyer Inc. By evaluating the control surfaces and geometry the team will be able to determine how
strongly the control surfaces are coupled. Initially the team will be evaluating three variables of which being wing
span, rudder size, and center of gravity location. Through evaluating the three areas of concern listed, the aircraft’s
performance in all three axis will be tested.
A. Wing Span
The first geometry change to be evaluated will be the wing span of the Silver Bird. The wing span will affect many
performance characteristics of the aircraft. The roll rates and handling in the lateral direction will be altered. Due to
constraints the wing span can only be increased by 3 feet on either side. The center of gravity will also be altered
when changing the wing span. This could increase the static margin of the aircraft which in turn would cause the
aircraft to become more stable in pitch. Finally increasing the wing span will also affect the yaw of the aircraft. The
tendency to yaw with a larger wing span will be decreased.
B. Rudder Size
The second geometry change to be evaluated will be the rudder size and location of the Silver Bird. This is a request
from Wright B Flyer Inc. By design of the aircraft there is a maximum rudder span that can be achieved with no
constraint for the chord of the rudder. Another factor to be considered is the distance between the two rudder panels.
The rudder effectiveness would like to be evaluated with various rudder spreads. In other words, model the aircraft
with a single rudder in the center of the tail boom and with the distance between to rudder panels equaling the
constraint spread distance of the tail boom width. The suggested geometry changes may affect the yaw rates
drastically.
C. Center of Gravity location
The final geometry change to the aircraft that should be evaluated is changing the location of the center of gravity to
increase the static margin. This process could be carried out a numerous number of ways. The location of the wing
itself could be shifted which would affect the static margin by both moving the aero center and the center of gravity.
Also the pilot seats could be shifted along with the fuel tanks. For the fuel tanks it has been requested by Wright B
Flyer Inc. to evaluate the aircraft with the fuel tanks in the lower wing rather than the top wing. This may also
increase the stability of the aircraft
Through the three geometry changes mentioned above the performance of the Silver Bird will be altered. It will be
the test pilots who determine if the aircraft behaves favorably or non-favorably after the changes. In addition, while
performing the design alterations new geometry changes may be suggested based upon the current performance at
the time. The overall goal of the design changes is to determine the sensitivity of the design changes and to evaluate
the performance in hopes of improving the handling characteristics and safety of the aircraft.
VI. Conclusion
The team was able model the Silver Bird into the MERLIN Flight Simulator with the performance characteristics
similar to the original Silver Bird. It was learned that the original Silver Bird was inherently unstable and required
stick down to fly steady level. In addition, the aircraft becomes dangerous to fly when using the ailerons due to a
rapid decent rate. The team will apply optional improvements by altering the aircraft’s geometry to change the
performance characteristics while in flight. The simulator acts as an engineering tool where the aircraft and aircraft
control coupling can be evaluated. The aircraft was able to be evaluated in order to achieve an accurate
representation of the previously fabricated Silver Bird. This will allow Wright B Flyer Inc. to determine the
sensitivity of the aircraft geometry on the flight characteristics and make the necessary improvements to the new
design.
Acknowledgments
The team would like to thank our mentors and sponsors for the opportunity to work on the project. Dr. Aaron
Altman, of the University of Dayton, served as the team’s advisor and mentor. The teams sponsor was the Wright B
Flyer Inc. The persons of contact were Mr. James Papa and Mr. Sam Carbaugh. Mr. Skip Hickey also served as a

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mentor for the team in which he assisted the team in his area of expertise of Flight Dynamics. In addition, a thank
you would like to be extended to Mr. Rich Stepler and Mr. Tom Walters for there time spent flying the Silver Bird
in the flight simulator. Their experience as pilots allowed the team to make the necessary adjustments to the design.
References
1
Neal, Chris, Excalibur II User’s Manual, Merlin Products Ltd. 2007.
2
Raymer, Daniel P. Aircraft Design: A Conceptual Approach. Washington, D.C.: American Institute of Aeronautics and
Astronautics, 1992. Print.
3
Roskam, Jan, Dr. Airplane Design. Ottawa, Kan.: Roskam Aviation and Engineering, 1985. Print.

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