P1: Nitrous at Balls in '08

Hybrid Launch Control

Last Update, 5/30/08 by Stephen Daniel

Project Summary

The goal of this project is to provide the LCO with the ability to control each valve, the quick-disconnect, and ignition circuit. In the test stand the valves include fire-suppression and possibly water cooling for the chamber pressure port.

This project does not control the nitrous tank chill system nor any aspect of the data capture system.

Essentially, there are two boxes. At the launch table there are a set of control switches. At the launch tower / test stand, we have a break-out box where each valve plugs in.

Photos of the finished control system can be seen here.

Design Goals

  • Very high reliability
  • Reusable across multiple projects
  • Capable of either 12V or 24V DC operation

High-Level Design Decisions

  • All connectors will be high-performance AMP connectors. These cost more than cheaper connectors, but experience has shown they just plain work.
  • All high-current paths will be local to the launch/test site. High-current does not run to the LCO table.
  • Connection to the LCO table will be wired, not wireless.
  • The entire circuit will be simple, very simple. No programmable parts.
  • All controls will be solid-state. High-current MOSFETs provide much higher price/performance than relays
  • The state of all outputs will be indicated by LEDs visible at the break-out box, but not at the control panel.
  • All control circuits will be identical. The only exception is the ignition circuit, which differs as follows:
    • The ignition circuit has a key-switch interlock on the control panel.
    • The ignition circuit uses banana-jacks as the connector, not AMP connectors. This allows us to measure connectivity to the igniter and igniter integrity after all connections have been made.
  • We will have 7 contol circuits. This allows us to use the 9-pin AMP connector to connect the boxes and provides all we can imagine needing. If we need more, we will build another box (possibly with fewer than 7 channels). Channels:
    1. Fill (tank-top)
    2. Line purge (tank-top)
    3. Quick-disconnect (vehicle external)
    4. Flight-tank dump (vehicle internal)
    5. Fire-suppression (test stand only)
    6. Pressure-port cooling supply (test stand only)
    7. Ignition (vehicle internal)

Break-out Box