Engineering Education-EngE 1024December 1, 2009

Created by: Erin Crede

Introduction to Experimental Design and Testing

Presentation Outline

•Learning Objectives

•Pre-Class Assignment

•In Class Activity• Materials• Logbook• Competition!• Sample Results

•Out of Class Assignment

•Possible Test Questions

Learning Objectives

1. Introduce students to experiment logbook preparation and use.

2. Introduce students to gliding flight, specifically performance calculations.

3. Construct, test, and evaluate a model glider.

Pre-Class AssignmentDuring class you will be designing and testing a wooden glider. In order to ensure a successful experiment, you must prepare your design and test logbook ahead of time. In addition to testing your own design, you will also be comparing your finished product to your competitors using the same criteria. Using excel, construct a logbook for your experiment using the reference material provided. Feel free to use additional resources with proper documentation . At a minimum your logbook should include:

•Group Member information•Glider parameters (weight, dimensions, locations etc)•Calculation for glide distance

Other information may include room for sketches, notes about design decisions, and any other information you may want to have for later use.

Sample LogbookWooden Glider Design and TestingDate: Dec 1, 2009Group Members: Erin ecrede@vt.edu

Will wiwalker@vt.eduJohn janja710@vt.edu

Instructions:

Working in teams of 4, design and build a wooden glider using the materials provided. Be sure to document the design in your logbook including drawings, dimensions, weight etc.

Glide Calculations:

glide distance is the height multiplied by the lift to drag ratio

drag is the dynamic pressure times the wing area and drag coefficient.

L lift equal to the weight of the glider

ParametersToss Height (h):Weight:SVdensityCd

D

L/Ddistance

Final Glider Design:

Weight:Tail spanTail ChordWing SpanWing chordFuse typeFuse Length

Material List/Cost for In Class Activity

MaterialUnit Cost

Total for Workshop Notes

Wood Sheet $0.25 $93.75 assuming 375 groups of 4 studentsRod $0.10 $37.50 assuming 375 groups of 4 studentsGlue $2.80 $70.00 assuming 25 groups simultaneously working

Single Use Material Total $3.15 $201.25

Cutting Tool $2.80 $70.00 assuming 25 groups simultaneously workingScale $5.00 $25.00 one scale per classroom (5 simultaneous classes)Tape Measure $2.00 $10.00 one per classroom (5 simultaneous classes)Ruler $1.00 $25.00 assuming 25 groups simultaneously working

Reusable Material Total $10.80 $130.00

Workshop Total $13.95 $331.25

In Class Activity

Class Activity Outline

(0-5 min) Pass out materials to each group

(5-10 min) Explain overview of activity

(10-35 min) Students build gliders and document in logbook

(35-45 min) Glider Competition!

(45-50 min) Students collect “competitor’s” information and final activity wrap

Note: 10 minutes available for use at instructor’s discretion

In Class Activity

General Activity Instructions:

Working in teams of 4, design and build a wooden glider using the materials provided. Be sure to document the design in your logbook including drawings, dimensions, weight etc.

Final Glider Design:

Weight: 0.15 lbsTail span 4 inchesTail Chord 1 inchWing Span 12 inchesWing chord 2.5 inches

Fuse type 0.25inch diameter

Fuse Length 12 inches

In Class Activity

Prior to the test flight, predict the glide time and distance your glider should be able to attain. Be sure to note these predictions in your logbook.Glide Calculations:

glide distance is the height multiplied by the lift to drag ratio

drag is the dynamic pressure times the wing area and drag coefficient.

L lift equal to the weight of the glider

ParametersToss Height (h): 5ftWeight: 0.15lbsS 0.208ft2V 20ft/sdensity 0.002241sl/ft3Cd 0.08

D 0.007458 lb

L/D 20.112distance 100.562 ft

In Class Activity

Glider Competition!

Each team should provide the following information about your glider prior to testing: (instructor can compile a set of tables)

•Wingspan•Chord •Fuselage type (rod thickness)•Weight•Throwing Height•Location of wing leading edge•Location of tail leading edge

Each team should make notes/sketches about each glider.

In Class Activity

Briefly comment on the results of the test flight prior to leaving class. Be sure to copy the competitors dimensions into your logbook for future calculations. If a single logbook was used for the activity, be sure to share the results among the group members.

Glider # Weight:

Tail span

Tail Chord

Wing Span

Wing chord

Fuse type

Fuse Length

Toss Velocity L/D

Glide Distance

Out of Class Assignment

Complete Logbook!

Each student should complete their logbook at home to submit the following week. In addition to the class activity, address the following:

1. Create a table or chart to compare each glider, comment on the designs.

2. Which glider should have gone the farthest based on the predicted glide distance?

3. Which glider actually travelled the farthest? Comment on the possible reasons for this discrepancy

4. If you were able to do this activity again, what would you have done differently:a. As part of the preparation?b. As part of the overall design?

Possible Test Questions1. For a given set of aircraft parameters, calculate the glide distance.

a. Five numeric answer choices

2. Which of the following are not directly used to calculate gliding distance?a. Aircraft weightb. Aircraft dragc. Height above groundd. Wing shapee. None of the above

3. Which of the following is generally true?a. Predicted glide distance is greater than actual glide distanceb. Predicted glide distance is less than actual glide distancec. Predicted glide distance is equal to actual glide distance

4. Which of the following not a use for a logbook?d. Planning an experimente. Storing data from an experimentf. Creating a record for experimental data collectiong. None of the aboveh. All of the above

Summary

The activity described addresses the following learning objectives:

While this activity was modeled after a popular aerospace activity, experimental design is an important concept for most engineering disciplines, specifically related to planning ahead, reflection on design decisions and theoretical versus actual performance measures.

Questions??

1. Introduce students to experiment logbook preparation and use.2. Introduce students to gliding flight, specifically performance

calculations.3. Construct, test, and evaluate a model glider.