📖 How to Use This Tutorial:
- Print: Click the blue button (top right) → Print or Save as PDF
- Navigate: Use browser Find (Ctrl+F) to search topics
- Practice: Follow along with the simulator open
📋 Table of Contents
- Introduction
- Quick Start (60 seconds)
- Interface Overview
- The 3 Factors (RB, Angle, Pin)
- Control Buttons
- Running Experiments
- Understanding Results
- Exporting Data
- DOE Applications
- Practical Examples
1. Introduction
What is the Statapult?
Statapult is a catapult simulator used to teach Design of Experiments (DOE) principles. By adjusting 3 factors (Rubberband, Angle, and Pin Position), students learn how different parameters affect the launch distance.
🎯 Learning Objectives:
- Understand how process factors affect output (distance)
- Learn to design and execute factorial experiments
- Identify main effects and interactions
- Apply statistical analysis to experimental data
- Optimize parameters for maximum performance
Simulator Capabilities
| Feature |
Description |
| ⚙️ 3 Factors |
Rubberband (2 levels), Angle (100-180°), Pin Position (2 levels) |
| 🎬 Animation |
2-phase realistic catapult motion (swing + parabolic flight) |
| 📊 Physics-based |
Projectile motion with gravity and realistic variability |
| 📈 History Tracking |
Complete experiment log with all parameters and results |
| 📉 Statistics |
Total runs, average distance, full data table |
| 📥 Export |
Excel (.xls) and CSV data export |
The DOE Connection
The Statapult simulator is perfect for teaching:
- Full Factorial Designs: Test all combinations (2³ = 8 runs)
- Main Effects: How each factor influences distance
- Interactions: When factors depend on each other
- Optimization: Finding the best settings
- Variability: Understanding process repeatability
2. Quick Start (60 Seconds)
✨ Follow these steps to run your first experiment:
Step 1: Select Factor A (Rubberband) → Choose RB = 2
Step 2: Set Factor B (Angle) → Drag slider to 140°
Step 3: Select Factor C (Pin Position) → Choose Pin = 1
Step 4: Click ▶️ LAUNCH
Step 5: Watch the animation (1.8 seconds):
- Phase 1: Arm swings back (0.3s)
- Phase 2: Ball flies in parabolic arc (1.5s)
Step 6: Check your results:
- Distance appears below canvas
- Experiment added to History table
Expected Results:
- Distance: ~280-320 cm (varies due to realistic randomness)
- Run #1 appears in History table
- Statistics show: Total: 1 run, Average: [your distance]
3. Interface Overview
Three-Panel Layout
┌────────────────────────────────────────────────────────┐
│ Statapult Interactive Simulator │
│ © 2025 KEEPLEAN Educational Tools │
├──────────────────┬─────────────────────────────────────┤
│ │ │
│ 📊 PARAMETERS │ 📈 EXPERIMENT HISTORY │
│ (35%) │ (65%) │
│ │ │
│ Factor A: RB │ Run │ RB │ Angle │ Pin │ Distance │
│ ○ 1 ⦿ 2 │ 1 │ 2 │ 140° │ 1 │ 287 cm │
│ │ 2 │ 1 │ 150° │ 2 │ 245 cm │
│ Factor B: Angle │ │
│ [━━━●━━━━━] │ Total: 2 runs │
│ 140° │ Average: 266.00 cm │
│ │ │
│ Factor C: Pin │ [🗑️ Clear] [📊 Excel] [📄 CSV] │
│ ⦿ 1 ○ 2 │ │
│ │ │
├──────────────────┴─────────────────────────────────────┤
│ │
│ 🎬 ANIMATION PANEL │
│ │
│ 🏹 ● → (catapult and ball) │
│ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━│
│ 0cm 200cm 400cm 600cm │
│ │
│ [LAUNCH] [RESET] │
│ Distance: 287.45 cm │
│ │
└────────────────────────────────────────────────────────┘
| Panel |
Location |
Purpose |
| Parameters |
Left (35%) |
Control the 3 factors: RB, Angle, Pin |
| History |
Right (65%) |
View all experiments, statistics, export data |
| Animation |
Bottom (full width) |
Watch launch, see distance, control simulation |
💡 Interface Design:
- Responsive: Adapts to desktop, tablet (35/65 split), and mobile (stacked)
- Clean: Professional layout with white background
- Real-time: Arm moves as you adjust angle slider
4. The 3 Factors (RB, Angle, Pin)
Factor A: Rubberband (RB)
| Property |
Description |
| Type |
Discrete (2 levels) |
| Levels |
1 or 2 |
| Control |
Radio buttons (click to select) |
| Effect |
Changes elastic force / initial velocity |
| Impact |
RB=2 gives longer distances than RB=1 (~30-50 cm more) |
How to Use:
- Click the circle ○ next to 1 or 2
- Selected option shows as filled circle ⦿
- Only one can be selected at a time
Factor B: Angle
| Property |
Description |
| Type |
Continuous |
| Range |
100° to 180° |
| Control |
Slider (drag left/right) |
| Effect |
Changes launch trajectory |
| Optimal |
Typically around 140-150° (depends on physics) |
How to Use:
- Click and drag the slider handle
- Angle value updates in real-time (e.g., "140°")
- The orange catapult arm moves to match the angle
- Any value between 100° and 180° is valid
💡 Visual Feedback:
Watch the catapult arm move as you adjust the angle. This helps you visualize the launch trajectory before clicking LAUNCH.
Factor C: Pin Position
| Property |
Description |
| Type |
Discrete (2 levels) |
| Levels |
1 or 2 |
| Control |
Radio buttons (click to select) |
| Effect |
Changes pivot point / lever arm |
| Impact |
Moderate effect, may interact with RB |
How to Use:
- Click the circle ○ next to 1 or 2
- Selected option shows as filled circle ⦿
- Only one can be selected at a time
5. Control Buttons
LAUNCH Button
| Property |
Description |
| Location |
Bottom panel, left side |
| Color |
Blue |
| Function |
Start catapult animation and record experiment |
| Duration |
1.8 seconds total (0.3s swing + 1.5s flight) |
What Happens When You Click LAUNCH:
- Phase 1 (0.3s): Catapult arm swings backward
- Phase 2 (1.5s): Ball launches and flies in parabolic arc
- Physics calculation: Distance computed based on RB, Angle, Pin
- Result display: Distance shown below canvas (e.g., "Distance: 287.45 cm")
- History update: New row added to Experiment History table
- Statistics update: Total runs and average distance recalculated
💡 Animation Details:
- Orange catapult arm with visible pivot point
- Red ball that follows realistic parabolic path
- Dotted trajectory line showing flight path
- Motion blur effect during flight
- Red impact marker where ball lands
- Distance scale with markers every 200 cm
RESET Button
| Property |
Description |
| Location |
Bottom panel, right of LAUNCH |
| Color |
Gray |
| Function |
Reset all factors to default values |
What RESET Does:
- Factor A (RB) → Set to 1
- Factor B (Angle) → Set to 140°
- Factor C (Pin) → Set to 1
- Catapult arm returns to 140° position
⚠️ Important:
- RESET does NOT clear the History table
- All your experiments remain saved
- Only the factor settings are reset to defaults
Clear Button (🗑️)
| Property |
Description |
| Location |
History panel, below the experiment table |
| Icon |
🗑️ Trash can |
| Function |
Delete ALL experiments from history |
⚠️ WARNING:
- This action CANNOT BE UNDONE
- All experiments will be permanently deleted
- Export your data FIRST if you want to keep it
Export Excel Button (📊)
| Property |
Description |
| Location |
History panel, bottom |
| Icon |
📊 Chart |
| File Format |
.xls (Excel XML Spreadsheet) |
| Filename |
statapult_data.xls |
How to Use:
- Run at least ONE experiment (button turns green)
- Click "📊 Export Excel"
- File downloads automatically
- Open in Excel, LibreOffice Calc, or Google Sheets
Export CSV Button (📄)
| Property |
Description |
| Location |
History panel, bottom |
| Icon |
📄 Document |
| File Format |
.csv (Comma-Separated Values) |
| Filename |
statapult_data.csv |
How to Use:
- Run at least ONE experiment (button turns green)
- Click "📄 CSV"
- File downloads automatically
- Open in Minitab, JMP, R, Python, or any text editor
Excel vs CSV:
- Use Excel (.xls): For quick viewing and basic analysis in Excel
- Use CSV (.csv): For statistical software (Minitab, JMP, R, Python)
- Both files contain identical data (Run, RB, Angle, Pin, Distance)
6. Running Experiments
Single Experiment Workflow
Step 1: Configure Factors
- Choose RB: 1 or 2
- Set Angle: Drag slider (100-180°)
- Choose Pin: 1 or 2
Step 2: Verify Settings
- Check catapult arm position (matches angle)
- Confirm all factors are as desired
Step 3: Launch
- Click LAUNCH button
- Watch 1.8-second animation
Step 4: Record Results
- Distance automatically displayed
- Experiment added to History table
- Statistics updated
Full Factorial Experiment (2³ Design)
The Statapult has 3 factors with 2 levels each. A Full Factorial Design tests all possible combinations:
| Run |
RB |
Angle |
Pin |
Notes |
| 1 |
1 |
110° |
1 |
Low-Low-Low |
| 2 |
2 |
110° |
1 |
High-Low-Low |
| 3 |
1 |
170° |
1 |
Low-High-Low |
| 4 |
2 |
170° |
1 |
High-High-Low |
| 5 |
1 |
110° |
2 |
Low-Low-High |
| 6 |
2 |
110° |
2 |
High-Low-High |
| 7 |
1 |
170° |
2 |
Low-High-High |
| 8 |
2 |
170° |
2 |
High-High-High |
💡 DOE Best Practice:
- Run all 8 experiments in random order
- This prevents bias from systematic effects
- Use a randomization tool or shuffle the order manually
Understanding Variability
Realistic Variation:
The simulator includes ±2% random variability to mimic real-world conditions. This means:
- Running the same settings twice gives slightly different distances
- This is NORMAL and REALISTIC
- In real experiments, no two runs are exactly identical
- This teaches the importance of replication and statistical analysis
7. Understanding Results
Experiment History Table
| Column |
Description |
Example |
| Run |
Sequential experiment number |
1, 2, 3, 4... |
| RB |
Rubberband setting used |
1 or 2 |
| Angle |
Launch angle used |
140°, 150°, 170°... |
| Pin |
Pin position used |
1 or 2 |
| Distance |
Launch distance achieved |
287.45 cm |
Statistics Display
| Statistic |
Description |
Example |
| Total |
Number of experiments completed |
"Total: 8 runs" |
| Average |
Mean distance across all experiments |
"Average: 287.45 cm" |
Calculating Main Effects
To determine which factors significantly affect distance:
Effect of Rubberband (RB):
Effect = Average(RB=2) - Average(RB=1)
Example:
Average at RB=2: 310 cm
Average at RB=1: 250 cm
Effect = 310 - 250 = +60 cm
Interpretation: RB=2 increases distance by 60 cm on average
Effect of Pin Position:
Effect = Average(Pin=2) - Average(Pin=1)
Example:
Average at Pin=2: 285 cm
Average at Pin=1: 275 cm
Effect = 285 - 275 = +10 cm
Interpretation: Pin=2 increases distance by 10 cm on average
Effect of Angle:
For continuous factors, plot Distance vs Angle to see the relationship. Typically:
- Low angles (100-120°): Shorter distances
- Optimal angle (~140-150°): Maximum distance
- High angles (160-180°): Decreased distances
Identifying Interactions
What is an Interaction?
An interaction occurs when the effect of one factor depends on the level of another factor.
Example:
- At Pin=1: RB effect = +50 cm
- At Pin=2: RB effect = +70 cm
- Conclusion: RB and Pin interact (effect changes with Pin level)
8. Exporting Data
Export File Contents
Both Excel and CSV files contain the same 5 columns:
Run,RB,Angle,Pin,Distance
1,1,140,1,245.67
2,2,150,2,312.45
3,1,130,2,278.91
4,2,160,1,298.34
...
Analysis in Excel
Step 1: Open Data
- Double-click statapult_data.xls
- Opens in Excel automatically
Step 2: Calculate Statistics
=AVERAGE(E2:E9) for mean distance=STDEV(E2:E9) for standard deviation=MAX(E2:E9) and =MIN(E2:E9) for range
Step 3: Create Pivot Table
- Insert → PivotTable
- Rows: RB or Pin
- Values: Average of Distance
- Compare means at each level
Step 4: Visualize Effects
- Insert → Chart → Scatter plot
- X-axis: Angle
- Y-axis: Distance
- Series: Group by RB or Pin
Analysis in Minitab
Step 1: Import CSV
- File → Open → Select statapult_data.csv
Step 2: Analyze Factorial Design
- Stat → DOE → Factorial → Analyze Factorial Design
- Response: Distance
- Factors: RB, Angle (treat as categorical with 2 levels), Pin
Step 3: Generate Plots
- Main Effects Plot
- Interaction Plot
- Pareto Chart of effects
- Normal Probability Plot
Analysis in R
# Load data
data <- read.csv("statapult_data.csv")
# Summary statistics
summary(data$Distance)
sd(data$Distance)
# ANOVA
model <- aov(Distance ~ RB * Angle * Pin, data=data)
summary(model)
# Main effects plot
library(ggplot2)
ggplot(data, aes(x=factor(RB), y=Distance)) +
geom_boxplot() +
labs(title="Effect of Rubberband")
9. DOE Applications
One Factor at a Time (OFAT) - Not Recommended
⚠️ Common Mistake:
Many beginners use OFAT approach - changing one factor at a time while keeping others constant. This method:
- Requires MORE experiments than factorial design
- CANNOT detect interactions
- May lead to suboptimal conclusions
| Run |
RB |
Angle |
Pin |
Notes |
| 1 |
1 |
140° |
1 |
Baseline |
| 2 |
2 |
140° |
1 |
Change RB only |
| 3 |
1 |
160° |
1 |
Change Angle only |
| 4 |
1 |
140° |
2 |
Change Pin only |
Problem: This gives 4 experiments but misses all interaction information!
Full Factorial (2³) - Recommended
✅ Best Practice:
Full Factorial Design tests all 8 combinations:
- Requires only 8 experiments
- Identifies all main effects
- Detects all 2-way and 3-way interactions
- Provides complete information
Response Surface Methodology (RSM)
For advanced users exploring the continuous Angle factor:
| Run |
RB |
Angle |
Pin |
| 1-4 |
1 or 2 |
100° |
1 or 2 |
| 5-8 |
1 or 2 |
130° |
1 or 2 |
| 9-12 |
1 or 2 |
150° |
1 or 2 |
| 13-16 |
1 or 2 |
170° |
1 or 2 |
This allows modeling the curvature of the Distance vs Angle relationship.
10. Practical Examples
Example 1: Beginner Exercise
Objective: Understand basic operation
| Run |
RB |
Angle |
Pin |
Purpose |
| 1 |
1 |
140° |
1 |
Baseline |
| 2 |
2 |
140° |
1 |
Test RB effect |
| 3 |
1 |
140° |
2 |
Test Pin effect |
Expected Learning:
- RB=2 gives noticeably longer distance
- Pin effect is smaller but still measurable
- Results vary slightly due to randomness
Example 2: Full Factorial 2³
Objective: Complete DOE analysis
| Run |
RB |
Angle |
Pin |
Expected Distance Range |
| 1 |
1 |
110° |
1 |
180-220 cm |
| 2 |
2 |
110° |
1 |
230-270 cm |
| 3 |
1 |
170° |
1 |
200-240 cm |
| 4 |
2 |
170° |
1 |
250-290 cm |
| 5 |
1 |
110° |
2 |
190-230 cm |
| 6 |
2 |
110° |
2 |
240-280 cm |
| 7 |
1 |
170° |
2 |
210-250 cm |
| 8 |
2 |
170° |
2 |
260-300 cm |
Analysis Steps:
- Export data to Excel/Minitab
- Calculate main effect of RB: Avg(RB=2) - Avg(RB=1)
- Calculate main effect of Pin: Avg(Pin=2) - Avg(Pin=1)
- Calculate main effect of Angle: Avg(170°) - Avg(110°)
- Create interaction plots (RB × Pin, RB × Angle, Pin × Angle)
- Determine optimal settings for maximum distance
Example 3: Optimization Challenge
Objective: Find settings that produce distance > 320 cm
Phase 1: Screening
- Run 8-experiment factorial (see Example 2)
- Identify which factors have largest effects
Phase 2: Angle Optimization
- Fix RB=2 (usually gives longer distance)
- Test angles: 130°, 140°, 150°, 160°
- Find the angle that maximizes distance
Phase 3: Confirmation
- Run 5 replicates at optimal settings
- Calculate mean and standard deviation
- Verify consistent performance > 320 cm
Expected Result:
Optimal settings typically around: RB=2, Angle=140-145°, Pin=2
This should yield distances of 310-330 cm consistently
Example 4: Variability Study
Objective: Understand process repeatability
| Replicate |
Settings |
Purpose |
| 1-10 |
RB=2, Angle=140°, Pin=1 |
Same settings, 10 times |
Calculate:
- Mean distance
- Standard deviation (σ)
- Coefficient of Variation: CV% = (σ / mean) × 100
- Min and Max values
- Range = Max - Min
Expected Results:
- Mean: ~290 cm
- Std Dev: ~5-6 cm (≈2% variation)
- CV%: ~2%
- Range: ~15-20 cm
This demonstrates the inherent variability in the process, teaching students why replication and statistical analysis are essential.
Troubleshooting Guide
Common Issues & Solutions
| Problem |
Possible Cause |
Solution |
| Simulator doesn't display |
Browser cache issue |
Hard refresh (Ctrl+F5 or Cmd+Shift+R) |
| Animation doesn't play |
JavaScript disabled |
Enable JavaScript in browser settings |
| Angle slider doesn't move |
Click not on handle |
Click and drag the slider handle specifically |
| Export buttons are gray |
No experiments run yet |
Click LAUNCH at least once first |
| Download doesn't work |
Pop-ups blocked |
Allow pop-ups and downloads for this site |
| Distance seems wrong |
Misunderstanding randomness |
±2% variation is normal; run multiple replicates |
| History table not visible on tablet |
Old version |
Use version with 35/65 column split |
| RESET doesn't clear history |
Working as designed |
RESET only resets factors; use Clear to delete history |
Quick Reference Card
Default Settings
| Parameter |
Value |
| Factor A (RB) |
1 |
| Factor B (Angle) |
140° |
| Factor C (Pin) |
1 |
Key Shortcuts
| Action |
Method |
| Launch experiment |
Click LAUNCH button |
| Reset to defaults |
Click RESET button |
| Clear all data |
Click 🗑️ Clear button |
| Export to Excel |
Click 📊 Export Excel |
| Export to CSV |
Click 📄 CSV |
Typical Distance Ranges
| Settings |
Expected Distance |
| RB=1, Low Angle |
180-230 cm |
| RB=1, Optimal Angle |
240-280 cm |
| RB=2, Low Angle |
230-280 cm |
| RB=2, Optimal Angle |
290-330 cm |
DOE Formulas
Main Effect (2-level factor):
Effect = Average(High) - Average(Low)
Interaction Effect (2-way):
Interaction = [Effect of A at B(high)] - [Effect of A at B(low)]
Number of Runs (Full Factorial):
Runs = k^n
k = levels per factor, n = number of factors
For Statapult: 2³ = 8 runs (with 2 angle levels)
Statistical Measures
Mean:
x̄ = Σx / n
Standard Deviation:
σ = √[Σ(x - x̄)² / (n-1)]
Coefficient of Variation:
CV% = (σ / x̄) × 100