After some requests on the TRA email list, I decided to try my hand at making a simple, small, inexpensive, gyro-based device that measures the rocket flight angle and inhibits an airstart ignition if the flight angle exceeds a user-selected angle threshold. This would be like Frank Hermes' Rocket Tiltometer, but without as many extra features. I have picked out the major parts and completed part of the layout, so I think it's time to finalize the features and interface, and for that I'd like any feedback people are interested in providing.
Here are the specs:
This is still in the early design stages, and wouldn't be available for a couple of months, at least.
Here are the specs:
- 3-axis gyro, and 3-axis accelerometer, and a bunch of math in a microcontroller determine the rocket's orientation before and during the flight.
- 1.5" long by 0.75" wide
- One switch connected to the + half of the circuit will prevent current to the ignitor by opening a solid-state switch when the flight angle exceeds a user-selected threshold.
- You can select the no-go angle from 2-34 degrees in increments of 2 degrees by turning a rotary DIP switch with a screwdriver.
- The board also has a solid-state switch that acts like a simple rocketry timer. You can connect the switches together to make a stand-alone tilt-safe timer.
- The timer values are selected by another rotary dip switch, that can select from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, or 30 seconds from liftoff, or an apogee setting that lets this switch be used by itself for a backup apogee charge.
- Single battery needed, 4-16V, up to 30 Amps current capability.
- LEDs to show when the unit has power, when the timer output has continuity, and when the tilt threshold is exceeded. I may also provide an LED and a pair of terminals to bring out a pad health check status remotely.
- No beeper, but the tilt meter is designed to work with the continuity check for most altimeters so there's just one device beeping status at the pad.
- No data recording
- Cost: Hopefully under $70
This is still in the early design stages, and wouldn't be available for a couple of months, at least.
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