Mission and Launch Challenge
+ Launch System
Welcome. For today you are not a student. You are an engineer at a contract firm, and a children's hospital just hired you to solve a real problem. Right now: accept the contract, and build the first version of your delivery system.
How do you deliver critical supplies across an impossible gap?
- Read the contract briefing from the hospital
- Build a rubber-band catapult launcher
- Test what your build can do
- Get ready to connect it to the receiving system this afternoon
This is the briefing your firm just received from a children's hospital's Facilities Engineering team. Read it like an engineer.
Location: A children's hospital, West Connector Bridge.
Status: A structural assessment identified critical integrity issues in the connector bridge linking the Main Building to the North Tower. The bridge is closed indefinitely. Estimated reopening: 6 to 8 weeks.
Patients affected: 64 pediatric inpatients in the North Tower.
Services impacted: Daily medication delivery, sterile supply transport, lab sample transport, equipment exchange. Couriers can do it on foot, but a 40-minute round trip means lab samples spoil and medications are late.
The hospital has put out a request for engineering proposals. Your firm is one of several being asked to design a mechanical delivery system that can:
- Move standardized payloads (300 to 500 grams) across a 20-foot gap between the Main Building rooftop launch deck and the North Tower receiving deck
- Operate without electricity (the affected wing has unreliable power)
- Land payloads in a specific receiving zone, not just "somewhere on the other side"
- Deliver payloads from the receiving deck down to the patient floor inside the building
- Work reliably: at least 3 successful deliveries in a row by end of day
Your deliverable: A working prototype that reliably delivers payloads from your launch position into the receiving zone. You show it to the room at the end of the day.
Hospitals genuinely use mechanical delivery. Pneumatic tube systems move tens of thousands of lab samples, prescriptions, and small supplies daily at major children's hospitals around the country. When those systems fail, hospitals have to engineer workarounds fast. The problem you are solving today is the same kind of problem biomedical and facilities engineers solve in real hospitals every year.
The catapult is your launch system. Right now you are not optimizing. You are getting a working version off the table.
Every catapult stores potential energy in stretched rubber bands. Release the tension and that energy converts to kinetic energy, the moving payload. That is the entire physics of your build. Everything else is engineering.
Goggles on before anyone touches a rubber band. Rubber bands snap. Eyes do not heal. Nobody aims a loaded catapult at a person. Ever.
- 12 dowel rods (12", 3/8" diameter)
- Rubber bands, assorted sizes
- 1 small cup or bottle cap (your launcher)
- Foam ball or weighted payload (your "medical supplies")
- Safety goggles, one per team member
- Access to a low-temp glue gun, shared across firms
Count your materials. If you are short, raise your hand before you start building.
- T-base: Lay 2 dowels in a T-shape. Lash them tight with rubber bands at the joint.
- Square base: Add 2 more dowels to close the T into a square. Lash all 4 corners. This is your foundation. Wobble here means wobble everywhere.
- Vertical posts: Stand 4 dowels up, one at each corner of the square. Lash each one tight to the base.
- Front bar: Lash a horizontal dowel across the top of the two FRONT posts. This is where your arm will pivot.
- Back support bar: Lash a horizontal dowel across the two BACK posts, a few inches LOWER than the front bar. This is your release stop and your tension anchor.
- The arm: Lash 2 dowels together end-to-end, with 4 to 5 inches of overlap. This gives you a long, strong throwing arm.
- Pivot: Lay the arm across the front bar. Lash it loosely so it pivots freely. Too tight and it will not swing.
- Tension band: Loop a rubber band (or several) from the back support bar to the launching end of the arm. This is your energy source. More wraps = more stored energy = more launch.
- Launcher cup: Use a dab of low-temp hot glue to mount your cup or bottle cap to the launching end of the arm. This holds your payload.
Goggles on. Clear the area in front of the catapult. No people, no pets, no other firms downrange.
Load a foam payload into the cup. Pull the arm down. Release.
Run 5 test launches. Do not change anything between them. Just see how consistent your build is.
For each launch, notice:
- Approximate distance (steps, feet, or tile count)
- Direction (straight, left drift, right drift)
- Anything that moved, bent, slipped, or broke on the catapult
Do not optimize yet. The goal of v1 is to find out what is loose, what is weak, and what you will fix this afternoon. A wobbly first build is normal. A first build that fires the same direction every time is rare, and if yours does, you got lucky on tight lashings.
Two-minute conversation with your team:
- What variable seemed to affect distance the most? Tension? Arm length? Release angle?
- Where is your catapult weakest? Where will it fail first?
- What is the number one thing you will change this afternoon?
Mechanical engineers design every machine in a hospital that moves: surgical robot arms, patient lifts, MRI tables, pharmacy dispensing systems, blood-draw chairs. Every one of them stores and releases energy in a controlled way. Your rubber band catapult is the same physics as a hospital pneumatic door closer or a hydraulic patient lift. Different energy source, same principles.
Launcher built. Now for the other half: Part 3 · The Receiving System.