Engineering sheets

The following engineering sheets can be used to help in the conceptual design of parachute systems. The assumptions of the pages are stated in the Excel sheet. The pages are free to be used by anyone designing a parachute system. If there are suggestions on new sheets, or improvements to our current sheets feel free to contact us. Chutes.nl does not take responsibility for any crashed mission that was designed with our sheets.

Ballistic Entry

Download: Ballistic Entry sheet

This sheet allows you to determine the deceleration, velocity, and thermal profiles of a non-lift generating ballistically entering body. These assumptions are relevant for re-entry with orbital velocities. The heat flux is calculated using Chapman's Equation. From this sheet, you can derive the location of peak deceleration and the altitude at which peak heating occurs. 

Parachute conceptual design

Download: Parachute conceptual design sheet

This sheet allows a rough estimation of the parachute areas and inflation loads. The most important assumptions are that the vehicle is always traveling at terminal velocity and that the parachute is inflated instantaneously. 

Parachute inflation

Download: Parachute inflation sheet

This sheet fills in for the missing inflation characteristics of the parachute conceptual design sheet. In these two sheets, one can determine the deceleration of the vehicle during parachute inflation. The second sheet allows for the same type of calculations but then with a reefed parachute.

Landing velocity sensitivity

Download: Landing velocity sensitivity sheet

The landing velocity is primarily a function of the drag generated by the parachute and the mass of the object. In this sheet, one can vary the mass and parachute area to get an understanding of the sensitivity of the landing velocity to these parameters. 

Streamer drag coefficient

Download: Landing velocity sensitivity sheet

The streamer is one of the simplest aerodynamic decelerators. It might not be the most efficient but it is definitely the simplest to make. This sheet helps you with sizing and designing the streamer.