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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Daniel

Graves






Project

Lead

James

Reepmeyer






Lead

Engineer

Brian

Smaszcz






Airframe

Design

Alex

Funiciello







Airfoil

Design

Michael

Hardbarger





Control

Systems

Project Definition

Mission Statement:



The goal of the UAV Airframe C project is to provide an
unmanned aerial platform used for an aerial imaging
system. The airframe must support the weight and
interfaces for the designed imaging system. The aircraft
must be operated remotely and be a viable alternative to
current aerial imaging methods. This is a second
generation airframe, expanding on the previously laid
ground work established by the P09232 UAV B Senior
Design Project.



Risk Management

Customer Needs

Key Project Goals:


Airframe must be able to carry a fifteen pound payload


Easy integration with measurement controls box and
different aerial imaging systems


Ability to remotely control aircraft and activate payload


Ability for flight communication between aircraft and
ground relay


Aircraft provides twenty minutes of flight time for local
area photography


Aircraft has the potential to take off and land on site


Easy assembly and disassembly of the aircraft for
transportation




Lessons Learned From P09232


The aircraft’s wings sheared off shortly before
impact. The failure was determined to be from the
bending stress applied to the wings during the
banked turned.




After analysis, it was concluded that the main
fiberglass spar used to support the wing was not
selected properly to handle the flight loading.



High bend in the wing during flight inhibited the pilot’s
control of the aircraft by reducing the effectiveness of
the control surfaces.



Design goals based on

lessons learned from P09232


Reduce wingspan (reduced bending
moment)



Re
-
enforce wing spar



Reduce plane weight



Re
-
evaluate electric propulsion

Engineering Specifications


The aircraft shall have a maximum weight of 25
lbs without payload (40 lbs gross)


The aircraft shall have a flight ceiling of 1000 ft


The aircraft shall be able to sustain a flight of at
least 40mph in calm conditions


The aircraft shall be capable of stable flight
with a 15 lb payload


The aircraft shall utilize an open architecture
payload interface


Engineering Specifications


The aircraft shall provide a mechanical interface to
the payload


The aircraft shall provide a secure anchoring
connection for the photographic instrument payload


The aircraft shall provide a secure mounting
location for the flight control electronics package
(P10236)


The aircraft shall sustain steady flight in a
controllable manner for at least 20 minutes


The aircraft shall be able to re
-
launch as soon as it
has been re
-
fueled or re
-
charged


Engineering Specifications


The aircraft shall be able to operate for at least 12
regular flights without needing routine maintenance


The aircraft shall be able to take off under its own
power from a 1000 ft grass runway


The aircraft shall have a sufficiently powerful motor


The aircraft shall be able to be transported in a motor
vehicle when disassembled


The aircraft should be easy to assemble and
disassemble by one person


The aircraft shall be able to navigate while on the
ground


Engineering Specifications


The final cost shall be less than the cost of renting
a Cessna for a day (~$8000)


The aircraft should have similar flight
characteristics to a trainer RC plane


The wing shall support the plane’s gross weight
under +4/
-
2 G loading


The wings shall not become detached from the
plane while in flight


The wings shall not deflect to a degree that
interferes with the operation of the flight control
surfaces (will not jam the servos)


Engineering Specifications


The propulsion system shall provide
uninterrupted, constant power for at least 20
min


The landing gear shall hold the plane at an
optimal angle of attack while on the ground


The servos shall be of sufficient power to
control the plane’s control surfaces at speeds
up to 50 mph


The aircraft shall be structurally sound; no
parts shall leave the aircraft while in flight


Learning from Airframe B


Based on Airframe B, worst case would
be a wing failure



Airframe B was successful in meeting
the total lift requirement

Design Objectives


Reduce the moment on the wing by
reducing the wing span



Provide enough lift to lift the 40lb
plane/payload

Wing Sizing


With a 9% cambered airfoil the same
lifting capabilities are possible with a
wing of 68% the total area



A NACA 9412 airfoil was chosen


10ft span


16in chord


AR of 7.5

Based on initial analysis using NASA’s
FoilSim

at an AOA of 6 and a Speed of 30 mph

Level Flight Speed
vs

AOA

Bending Moment Reduction

Optimum Cruise


Cruise at best
Cl
/
Cd

ratio
possible



Speed of ~41 mph


Wing AOA of 2.5
degrees

Tail Design


Horizontal Tail Area




S
HT
=2.222 ft
2


Vertical Tail Area




S
VT
=1.333 ft
2


Equations from
Aircraft Design

by Daniel P.
Raymer

Horizontal Tail


Tail located 4 feet behind wing


Inclined at
-
4 degree to the planes axis


Symmetric Foil


NACA 0408

Cruise Pitching Moment


Zero moment at
cruise speed


Allows for level flight
at cruise

Control Surfaces


Horizontal Tail


C
e
/C
HT
=.45


C
e
=3.375 in


Vertical Tail


C
r
/C
VT
=.40


C
r
=3.2 in



Ailerons


Placed on outer wing segments


Surface of 2.5ft


Covering a total of half the
wingspan


Chord of 3in


0.1875 the Wing Chord

Suggested size ranges from
Raymer’s

Aircraft Design

Takeoff Analysis



L)
μ(W
Drag
Thrust
g
W
a




www.leancrew.com

Ground Friction Experiment

2
.
cos
sin








N
T
T
W
N
dept.physics.upenn.edu

Climb

www.grc.nasa.gov

Climb Angle of 8
o

Flight Ceiling of 1000ft

Cruise Segment

www.grc.nasa.gov

Voltage
Power
Current
ncy
propeffice
Drag
MotorPower
C
C
Weight
Drag
d
l
/
/



Propulsion Analysis


After lots of decisions decided to go with
empirical method of electric motor
selection


Use 50W per pound minimum to takeoff


Use 75W per pound to attain “Trainer”
-
like Flight


Our Motor Needs to be minimum of
2000W to takeoff


The more motor power the more flight
control


Propulsion BOM

Propulsion Summary

DC Brushless Motor


AerodriveXp

SK Series 63
-
74

-

Produces 3200W at 37V

Power Source


Zippy
MaxFlight

-

18.5V and 5000mAh per pack

-

4 Total Needed (2 in Series, 2 in Parallel)

-

Total of 10000mAh at 37V

Speed Controller


Turnigy

Sentilon

-

100A

UBEC


Turnigy

5
-
7.5A UBEC for
Lipoly

Propeller


XP Type B Propeller 24x10

Landing Gear Summary


Front landing gear used will be the one designed
for UAV B, in order to save on cost.


Tail landing gear will be an off
-
the
-
shelf system
designed for large airplanes.


Ohio Superstar Maxi Tail Gear (30
-
50lb planes)

Landing Gear Layout

http://www.jacksonrcclub.org/images/landing_gear_types.jpg

Front Landing Gear Analysis


Front landing gear was designed and analyzed
for UAV B and fitted for UAV C.


Since the landing gear was designed for the
impact load of a higher weight plane it will work in
this application.


Detailed analysis and method is unavailable


Complete FEA analysis of the part in the future to
ensure reliability.

Tail Landing Gear Assembly


Tail landing gear was selected as an off
-
the
-
shelf
system from an online hobby shop.


Due to the high weight application and high cost,
retractable tail landing gear was not justified.


Three possibilities for tail Gear:


Ohio Superstar
Haigh

Super Tail Gear (30
-
50lb plane)


Ohio Superstar Maxi Tail Gear (30
-
50lb plane)


Sullivan Tail Wheel Bracket (16
-
35lb plane)

Information selected from Tower Hobbies.
http://www.towerhobbies.com/

Tail Landing Gear Selection


Sullivan


Target weight of UAV C is 40 lbs or less. Sullivan tail
gear does not meet this maximum load.


Ohio Superstar
Haigh


Meets the target requirement


Contains all necessary parts (wheel, bracket, etc)


Costs $32.00


Ohio Superstar Maxi


Target weight of UAV C is 40 lbs or less. Sullivan tail
gear does not meet this maximum load.


Contains all necessary parts (wheel, bracket, etc)


Costs $22.60

Final Landing Gear Selection


The front landing gear will be the one designed
for the UAV B. This is because it is readily
available and inexpensive.


Cost: Free


Tail landing gear will be the Ohio Superstar Maxi
Tail Gear (30
-
50lb planes) because it meets the
necessary plane requirements while being the
least expensive option.


Cost: $22.60


Total System Cost: $22.60


Main Spar Design Summary


Dragon Plate braided carbon fiber circular tubing
will be used as the main spar.


Cost: $237.00


Dimensions:


OD:

0.79”


ID:

0.54”


Length:

48”

Main Spar Analysis


Assumptions


At steady, level flight the wing is loaded uniformly
across the span.


Main spar supports the entire weight of the plane by
itself.


From the wing root outwards the spar behaves as a
cantilevered beam.


Normal flight load is 40
lbf


Design will be to 5 g acceleration per guidelines in the
RCAdvisor’s

Model Airplane Design handbook.


Due to symmetry, half the wing will be analysis.

Main Spar Analysis


Design Considerations


Must remain under materials yield strength
(elastic region) to avoid permanent deformation.


Must not deflect excessively at flight load
(less than 1 foot) in order for control surfaces to
maintain effectiveness.


Must be light in order to keep the weight of the aircraft
at a minimum.


Must be competitively priced compared to other
options.

Main Spar Analysis


Materials


Materials were selected that are readily available and
have associated engineering data provided for
analysis.


A supplier for fiber glass tube could not be found
which supplied the correct spar dimensions as
well as the appropriate engineering data for
analysis.

Main Spar Analysis

Main Spar Analysis


Aluminum 2024
-
T6


Yield Strength: 50
ksi


Modulus of Elasticity: 10500
ksi


Aluminum 6061
-
T6


Yield Strength: 40
ksi


Modulus of Elasticity: 10000
ksi


Dragon Plate Braided Carbon Fiber


Yield Strength: 600
ksi


Modulus of Elasticity: 43000
ksi

Material properties for aluminum are taken from http://www.matweb.com

Material properties for Dragon Plate are taken from http://www.dragonplate.com

Main Spar Analysis


The target size for the spar was set at an
approximate OD of 0.75” and an ID of 0.5”


Since Dragon Plate carbon fiber has the best
tensile strength, a tube profile which is readily
available was selected to test against.


Aluminum 6061
-
T6 was not analyzed as it has
provides less benefit than 2024
-
T6.


Test Profile:


OD: 0.79”


ID: 0.54”

Main Spar Conclusions


Please see accompanying handout for Analysis




Dragon Plate braided carbon fiber rods will be
used as the main spar


Superior factor of safety at flight loads


Better at resisting deflection


Lower weight


Higher cost but provides vast improvement over
Aluminum 2024
-
T6 ($87.24 difference).


Airframe Design

Airframe Design

Airframe Design

Payload Interface

Payload Interface

Aft
-
Section Design

Control Hardware Mount

Control Hardware Mount

Front Landing Gear Mount

Wing Mount

Control Interfaces (physical)

Control Interfaces (electrical)

Daniel

Graves






Project

Lead

James

Reepmeyer






Lead

Engineer

Brian

Smaszcz






Airframe

Design

Alex

Funiciello







Airfoil

Design

Michael

Hardbarger





Control

Systems