MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 1
Name: _______________________________________ Team ___________________
Item
ATV Lift Lift Table Score Co
ections
1 Top Pad /10 Table /10
2 Active Lift Arm /20 Idler Frame /15
3 Base Assembly /30 Active Frame /15
4 Base Assembly /20
5 Wright Flyer Calculations /40
Total (Individual) Score /100
Total Percent %
Multiplied by 10.00% %
On Time: 0.20% %
Added to Grade %
Hand in ONE cover sheet each with Shear & Moment Diagrams and
Wright Flyer III calculations
(This assignment is for individual scores only)
There are two XXXXXXXXXXx 17 prints to
go with this assignment – be sure
that you get them.
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 2
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 3
Use your Statics calculations from last week (and the position of the ATV Lift or Lift table that you
worked with) to draw Shear & Moment Diagrams.
Use only the Components of the Forces perpendicular to the member involved (except the Lift
table Active Frame and Base Assembly).
Remember that these diagrams are “cumulative”.
o The Shear Diagram goes up or down from its previous value according to the value of
the Load.
o The Moment Diagram goes up or down from its previous value according to the area
under the Shear Diagram to the previous point.
Draw Load, Shear & Moment Diagrams for a Member on a single sheet.
o Pencil or AutoCAD is fine, but not MDSolids as I want you to think this through.
o Make sure things line up vertically and are reasonably in proportion.
o Show units.
ATV Lift: (if that is the project that you chose)
Top Pad:
Draw the Shear & Moment Diagram for the Top Pad.
The forces on the Idler Lift Arm are axial (it acts as a Link) therefore there are no shear forces (the
components perpendicular to a link are zero) and therefore there are no bending moments. Do not
draw this!
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 4
Active Lift Arm:
To make sense of the Active Lift Arm, rotate both its
FBD and its force triangle so that the Active Lift Arm is
horizontal. See diagram right. Draw rectangles
around the force vectors of the rotated triangle to
find the components perpendicular to the Lift Arm
and use these to draw the Shear & Moment
Diagrams. See right. Note how the line of action of E’
is ca
ied to the dashed line connecting A & D (the
5.5050 dimension in the upper right diagram).
Base Assembly:
Finally, draw the Shear & Moment diagrams for
the Base assembly. There is no need to rotate this
as it is already horizontal. Use only the
perpendicular components.
See attached example (Active Lift
Arm) from AutoCAD
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 5
Lift Table:
Table:
Draw the Shear & Moment Diagram for
the Table.
Idler Frame: (See attached AutoCAD drawing)
The Idler Frame is not a Link (forces are applied at three places).
Add Vectors to your AutoCAD drawing to represent the forces.
They should be to a representative scale. Create a Dimension
Style to show the values of the forces.
Rotate the Idler Frame with the forces so that the line
connecting the points of application of the forces is
horizontal.
Draw rectangles around the force vectors and
dimension the components perpendicular to the
line connecting the points of application.
Use this to create the Shear & Moment Diagrams.
You will need a new dimension style for the
moment measurements.
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 6
Active Frame: (See attached AutoCAD drawing)
Add Vectors to your AutoCAD drawing to represent the
forces. They should be to a representative scale.
Create a Dimension Style to show the values of the
forces.
Rotate the Active Frame with the forces so that the line
connecting the points of application of the forces is
horizontal.
Draw rectangles around the force vectors and dimension the
components perpendicular to the line connecting the points of
application.
Use this to create the Shear & Moment Diagrams. You will need a new
dimension style for the moment measurements.
o NOTE: Where the Piston attaches there is a large horizontal component which is OFFSET
from the line connecting the points of application. This is seen in the attached AutoCAD
drawing as 400.44lb offset 1.50”. This means that there is a moment acting here and
must be acknowledged.
o Multiply the two numbers together: XXXXXXXXXXx 1.50 = 600.7lb.in
o This value does not affect the Shear Diagram, but is included directly in the Moment
Diagram. In this case, clockwise is positive (unlike the convention ibn Statics).
Base Assembly:
Finally, draw the Shear & Moment diagrams for the Base assembly. There is no need to rotate
this as it is already horizontal.
o However the attachment point of the Cylinder is seriously offset from the line where the
Active and Idler frames attach. This must be taken into account as in the Active Frame.
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 7
The original Wright Flyer from 1903 only ever flew at Kitty Hawk where a consistent head wind allowed
the aircraft to lift into the air despite the limits of a 12hp engine.
Continued flights in Ohio used a weight driven catapult to
launch the Flyer III (despite an improved 21hp engine).
The weight was 1400 lb and fell 16.5 ft. The weight was
connected to the aircraft through, first, a 3:1 compound
pulley and then through two more pulleys to launch the Flyer
along a rail. The 3:1 compound pulley meant that the aircraft
was pulled 3 x 16.5 = 49.5 ft along the rail before the pilot
eleased the rope pulling the aircraft.
All during launch, the engine was also running. The 21 hp
engine could drive the Flyer III at 35 mph. The Flyer III needed to reach 27 or 28 mph to remain in the
air.
The aircraft empty weighed 780 lb. Assume Wilbur or Orville weighed 160 lb.
MCDESG-125 Design Problems
Assignment 4C
Shear & Moment Diagrams; Work, Power, Acceleration
MCDESG-125 Page 8
1. How much work (Work = Force x distance) was done when the
weight fell?
2. If the work done to the aircraft is the same as the work done by
the falling weight, but the distance is tripled by the pulley system,
what is the force pulling the aircraft when the weight is falling?
3. Power is Work per unit Time. It can also be expressed as Force x
Velocity. The engine is 21 hp and can push the Flyer III at 35 mph.
What thrust can the engine achieve? (Convert mph to ft/sec; one
hp = 550 ft.l
sec)
4. F = ma where m = W/g (g = 32.2 ft/s²). Add the two forces – thrust
and pull – and find the acceleration of the Flyer with the pilot aboard.
5. This acceleration is applied all along the length of the rail (49.5 ft). What is the final speed of the
Flyer? If 27-28 mph is the minimum required for flight, is the Flyer ai
orne? (Check your history
ooks if you say “No”.)
YouTube video showing a launch with catapult (not the Wright Flyer III, but close enough – likely a
Wright Model A as there is a passenger. This would be the 4 cylinder upright engine of 35 or 40 hp)
https:
www.youtube.com/watch?v=RriKI7u72Xs
https:
www.youtube.com/watch?v=RriKI7u72Xs
Drawing Name
JimmyT
5 Mar.'20
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ANGLES
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X.XXX
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X.XX
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X.X
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UNLESS OTHERWISE
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TOLERANCES
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DIMENSIONAL
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SPECIFIED
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N/A
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SIMILAR
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TITLE
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DWG.No.
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125-04-0LH
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FRACTIONAL
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%%P1/64
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D
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SCALE
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PRINT
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SCALE
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1:2
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2/3/2021 12:10:34 PM
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PRINT
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DATE
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Wisconsin XXXXXXXXXX
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700 West State Street
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Milwaukee,
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ATV LIFT: MID-POSITION SHEAR & MOMENT
Sheets and Views
D Size FBD Mod (2)