A hobby I have had since early childhood is the construction and operation of model rockets – both the pre-fabricated kits from Estes and home made designs. Through a project that lasted from spring through fall of 2010, I took my model rocketry interests to the next level and developed an iterative solving rocket flight profile calculator using excel, and built a three-pad cluster-engine compatible modular electric launch system.

My model rocketry one dimensional iterative solver can calculate trajectory, and the following properties of the flight profile:

1. Total Impulse

2. Thrust Duration

3. Maximum Altitude

4. Maximum Velocity

5. Parachute Deployment Altitude and Rocket Speed at Deployment

6. Approximate Drift Distance After Deployment of Parachute (given a crosswind speed)

7. Total Approximate Flight Time

8. Descent Velocity After Deployment

These flight parameters are functions of the following design parameters and properties:

- Air Density (assume constant)
- Coefficient of Drag (approximate)
- Rocket cross sectional (projected) area
- Rocket mass
- Propellant Engine Packaging mass
- Two Stage / One Stage Designs
- Engine Clustering (assuming we can only cluster the first stage of flight if using boosters)
- Transient Thrust Profile of the ‘Estes’ model rocket engines

The calculator accounts for the following dynamics:

- Changing rocket mass as propellant is burned (assumed a linear burn rate)
- Changing rocket mass if a booster is ejected (including engine packaging)
- Engines of form factor B through E (properties available from Estes: packaging mass, propellant weight, total impulse, thrust profiles, etc.)

My calculator is available for download, here.