propulsion team the university of alabama andrew treadway, kelli harding, ryan miller, daniel...

Propulsion TeamThe University of Alabama

Andrew Treadway, Kelli Harding, Ryan Miller,

Daniel Stucki, Timothy Nash

10/27/2014

Lift EngineEngine Mount Fan Calculations

Briggs & Stratton Vertical Engine • Same as last year-Works well

• 6.5 HP @ 3600 RPM

• Vertical shaft

• Weight: 24.3 lbs (w/o fuel and oil)

• Ready start system

• 1.0 quart fuel tank w/ Fuel Pump

• Muffler included


• Modify previous year’s design• Works well, minor issues


• 24 inch fan diameter

• 5 blades

• Pitch angle adjustable to 45°

• Weight: 7.5 lb


Hovercraft parameters:

• Length: 160.3 in • Width: 68.3 in• Footprint area: 9544 in2

• Weight: 500 lb

Thrust EngineEngine Mount Fan/Prop Calculations

Kholer PAE-CH740-3003• Improved over last year’s design

• Lighter Weight• More Horsepower• Electronic Fuel Injection

Brand Kholer Kholer Kholer

Type CH740-3003 CH740-3002 (old) CH740-3002 (new)

Power [hp] 27 27 25

Compression Ratio 9.1:1 9.0:1 9.0:1

Weight [lb] 108 115 94

Displacement [cc] 725 725 725

Power-to-Weight [hp/lb] 0.2500 0.2347 0.2660


• Modify last year’s mount design

• Reduce vibration

• May do preliminary design to dampen vibrations on current craft


• Decided on fan• Adjustable pitch and blades• Easily replaceable blades (also cheaper)• Same dimensions as old craft (propulsive

screws are interchangeable)

• Re-order wooden prop for 2014 craft• Ensure correct parameters

Vs.


• Regulations• Max Engine Speed: 3600 RPM• Max Tip Speed: 330 ft/s

• Max Fan Speed (4 ft diameter)

• Gear Reduction:


Diameter (ft) A (ft2) mass flow Ue T Tstatic

3.50 9.621 0.8911 183.21 137.16 163.27

3.66 10.55 0.9780 175.10 142.60 171.26

3.83 11.54 1.0690 167.71 147.95 179.2

4.00 12.56 1.1639 160.94 153.22 187.33

4.16 13.63 1.2630 154.72 158.39 195.41

U0 29.308U1 39.1ρ 0.002369Ps 14575 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3

0

50

100

150

200

250

Static Thrust

Thrust @ 20 mph

Thrust vs. Diameter

Diameter (ft)

Thru

st (l

bs)

Ducts

Lift• Same design as last year• 24 inch duct• Weight: ~5lb

Thrust• 48 inch duct• Weight: ~10 lb• Will be strengthened with fiberglass

and sheet metal for protection

Both ducts will be built with better techniques to ensure constant diameter

Skirt

• Skirt material left over from last year• Will use same design, slightly

modify dimensions

• Last year forced to add holes• Will build a better balanced craft to

alleviate issues

Questions?

Structures TeamThe University of Alabama

Amber Deja, Victoria Reasoner, Clay Lemley

10/27/2014

Hull Design

• Based on Chris Sorgatz’s design

• Similar to 2013-2014 Hoverteam design

• 160.3 inches long (Approx. 13.35 ft.)

• 68.3 inches wide (Approx. 5.7 ft.)

MaterialsHull Structure Fiberglass Resin Other

• Polypropylene honeycomb material• 1” thickness – 3 sheets• 0.5” thickness – 9 sheets• Total of 384 ft2 will be ordered

• Light (total of 35 lbs. to construct hovercraft)• Aids in flotation

• Cost effective• $55 per 1” sheet• $35.75 per 0.5” sheet

• Ease of use• Cuts smoothly


• Inquired about other types of honeycomb• Polycarbonate• Aramid fiber

• Contact at Plascore stated polypropylene is the type of honeycomb most widely used for laying up with fiberglass


• Both carbon fiber and fiberglass were considered• Carbon fiber costs 4-6 times as much

• Want to keep the craft light but strong• Previous team used 4 oz. E-Glass woven cloth

• This year, 4 oz. S-Glass woven cloth will be used


• S-Glass is used when extra strength is needed and extra weight is not desired• 40% higher tensile strength• 20% higher modulus• Greater abrasion resistance• Same working qualities as standard E-Glass

• Considered using a heavier E-Glass cloth instead• More resin required• Increased weight of craft


• Four brands of epoxy resin were compared

• West Systems 105 was chosen• Most widely used, reliable brand• Competitively priced with other resins of the

same quality

• 4.35 gallon pail will be ordered


• West Systems 205 Fast Hardener• 9-12 minute working time• 6-8 hour drying time

• West Systems 206 Slow Hardener• 20-25 minute working time• 9-12 hour drying time

• Slow hardener will be used • Both have same cost• Increased working time is a plus• Increased drying time will not be an issue


• Fiberglass Shears

• Plywood• Create molds to piece together plenum

chamber

• Heavy Duty Adhesive• Piece together plenum chamber before

fiberglass is applied

• Paintbrushes


• Epoxy Pumps• Ensures correct ratio of resin to hardener

• Disposable Gloves

• Disposable Cups• For mixing resin and hardener

• Sandpaper

CostsItem Cost

Plascore $617.00Fiberglass (500 sq. feet 4 oz. S-Glass) $415.00Epoxy Resin/Hardener (4.35 gal/1 gal) $453.00

Resin Pumps $12.00Heavy Duty Adhesive (Three 28 fl. oz. bottles) $25.00

Plywood (Three 4’x8’ sheets) $25.00Fiberglass Shears $35.00

Other (gloves, cups, etc) $100.00Total Estimated Cost $1,682.00

ImprovementsBalance Structural Weaknesses Measure

Twice, Cut Once

• 2014 racecraft is very back heavy• CG is not at optimum location• Driver had to lean forward to attempt to

balance the craft while racing

• Lift duct was moved further toward back of craft than was originally designed• Contributed to CG being too far aft• 2015 racecraft lift duct will be moved back to

original designed location

FrontHovercraft Hull

160.3 in

80.15 in

Actual CG at 93 in

Side View of 2014 Racecraft


Twice, Cut OnceAddition of fiberglassed honeycomb lip to add more support for the deck

Fiberglass both sides of plenum chamber stiffener


Twice, Cut Once

• 2014 Racecraft• Jigsaw used to cut all pieces of honeycomb• Cuts were not necessarily straight• Angles were not properly cut• Pieces didn’t fit together properly – gap fill used as a remedy

• 2015 Racecraft• Measure TWICE, cut ONCE• Tablesaw will be used, especially for larger pieces and to cut angles properly• Avoid using gap fill

Questions?

Controls and Electronics Team

The University of Alabama

Jacob Wilroy, Ashely Reasoner, Liang Zhu

Ethan Slusher, Sara Guiley

10/27/2014

Stator VanesTheory Applications Construction

• Spinning motion of fan/propeller imparts swirling motion to the air moving through the duct. Fans tend to induce more swirling motion than propellers.

• Using stator vanes, we can translate the rotational momentum of the air into backwards momentum (thrust)

• Stator vanes also serve a structural purpose, adding rigidity to the duct, especially near he rudders.

• Trying to achieve better aerodynamics within the duct.

Region of separation = increased drag x 4 x 2

Stator VanesTheory Construction

• Blade twist leads to change in velocity vector direction

• Linear blade twist = linear cut along curved portion of stator


• Stators can be created using a mold and vacuum bagging technique.

• Mold can be created from sheet metal bent at the appropriate angle and given the correct curvature.

• Multiple stator vanes can be created from a single mold.

• Vanes will be attached to the duct by fiberglass

• Center piece will be created from Styrofoam covered with fiberglass. All vanes will attach here.


• Make stator from plastic fan blade

• Twist blade to get the correct pitch

• Smooth leading edge of fan blade will be better than sharp edge of fiberglass “plate”.

• Use fan blade = use hub in the center

• Make stator blades optional/removable


Vacuum Bagging: (www.carbonfiberglass.com)• Basic kit - $161.50• 1 VentVac Plus Venturi Vacuum Generator• 2 Yds of Peel Ply• 1 Yd of Bleeder Breather Cloth• 1 Yd of Vacuum Bag• 1 Roll of Sealant Tape (25ft.)• 2 Yds of Vacuum Tubing

Vacuum Bagging Benefits:• Needed for molding of parts• Can acquire the shape you need• Can be used year after year• Helps to remove trapped air and

distribute resin/hardener

Control Surface - RuddersPrevious Design New Design

Last year’s design• 5 rudders of the same dimensions

• Utilize 70 % of flow area

• Evenly spaced across diameter

• Rudder size: 24 in x 7 in

• Rudder shape: triangle

• Rudder weight: 10.29 lb


Rudder shape

• Rudders bend and deform easily

• Consider a stiffer shape or material


Option 1 Design• Four control surfaces• Evenly spaced across diameter• Utilize entire duct flow area

• Two panels: 47 in x 10 in• Two panels: 38.4 in x 10 in

• Constraint: 48 in diameter duct

Top View Front View Side View


• Four Rudders – (width of 0.0625 inches)

• Material: Aluminum

• Density: 169 lb/ft3 or 0.098 lb/in3

• Rudder shape: Triangle

• Rudder volume(long): 57.75 in3

• Rudder volume(short): 48 in3

• Total weight: 20.727 lb


Option 2 Design• Three control surfaces• Evenly spaced across diameter• Utilize entire duct flow area

• One panel: 48 in x 10 in• Two panels: 41.5 in x 10 in

• Constraint: 48 in diameter duct

Top View Front View Side View


• Three Rudders – (width of 0.0625 inches)

• Material: Aluminum

• Density: 169 lb/ft3 or 0.098 lb/in3

• Rudder shape: Triangle

• Rudder volume(long): 60 in3

• Rudder volume(short): 51.95 in3

• Total weight: 16.06 lb


Turning angle is mostly based on the push-pull cable actuation length. In order to give ourselves a fighting chance, we will purchase the longest cable possible.

Upon installation of the first set of rudders, we will find a turning angle that produces the largest turning force. From there the maximum turning angle can be set.

Cockpit Discussion Calculations

• Reduce quantity of fuel• Move fuel to a different location

• Creates more problems• Shift cockpit forward• Shift rear components (P-duct, P-

engine, rudders) forward to achieve correct CG

Cockpit Discussion Calculations

Component Weight [lb] Local CG Refernce Distance [in] Moment [in-lb]Lift Engine 30 32 960Lift Engine Mount 15 32 480Lift Duct 37 32 1184Driver 170 74 12580Fuel Tank fully loaded 39 77 3003Battery 6 46 276Propulsion Engine 125 111 13875Propulsion Engine Mount 30 118 3540Propulsion Duct 90 129 11610Upper Pulley 15 118 1770Fan and Hub 10 129 1290Rudders 50 142 7100Plascore Hull 35 86 3010Fiberglass Hull 172 86 14753CG Location: 92 inches

• Best option is to shift engine, rudder, and propulsion duct forward

Move everything up 4 inches with lift duct :88 inches!

Move propulsion engine, mount, duct and rudder up another 7 inches: 84 inches!

Questions?

propulsion team the university of alabama andrew treadway, kelli harding, ryan miller, daniel...

Documents

years mount design

liftsame design

preliminary design

hoverteam design

craft light

chris sorgatzs design

weight hplb0

better balanced craft