AspireSpace H2 Hybrid Motor - Avionics Systems
(PROVISIONAL)


Off-the shelf
Item Source Component Cost Personnel Location for
Manufacture		 Status
Flight Computer CaseJames MacfarlaneThe Batcave
Flight Computer CPUJames MacfarlaneThe Batcave
Flight Computer Circuit board ComponentsJames MacfarlaneThe Batcave
Flight Computer Circuit BoardJames MacfarlaneThe Batcave
Flight Computer external connectorsJames MacfarlaneThe Batcave
Flight Computer BatteriesAnyOff-the-shelfOff-the-shelf
Flight Computer SoftwareMike ProctorMike Proctor's House
Parachute TimersJames MacfarlaneConstructedFlight Ready
Parachute Timer BatteriesAnyOff-the-shelf
Pressure / Altitude SensorMaplin Electronics18 GBPJames MacfarlaneConstructedFlight Ready
Pressure / Airspeed SensorMaplin Electronics18 GBPJames MacfarlaneConstructedFlight Ready
Accelerometer
Thermal sensor
CCD Video CameraMaplin Electronics250 GBPJames MacfarlaneConstructedFlight Ready
Telemetry SystemFarnell Electrical ComponentsJames MacfarlaneConstructedFlight Ready
ALTACC Altimeter / AccelerometerBlack Sky Research120 GBPRichard OsborneConstructedFlight Ready


Low altitude flights - avionics information.

The avionics system specified for the low altitude hybrid test flights, is an extremely basic set-up. The basic system is specified with the following subsystems:

  1. Flight Computer (with onboard non volatile data storage).
  2. Engineering Sensors (Altitude, Airspeed, Acceleration, Temperature).
  3. Parachute Timers

Optional extra subsystems are:

  1. Telemetry equipment
  2. Onboard Video Camera
  3. ALTACC Accelerometer / Altimeter

Note, telemetry is not necessary - the specification calls for the approach of storing the data onboard. Given that the flight regime of interest for the engineering data, is from launch ignition until apogee, it will be possible to use an 8K Electrically Erasable PROM (EEPROM), for non-volatile data storage (i.e. the data will be stored even after power is removed from the chip).

The specifications for this application are 8 data channels sampling at a rate of 20 samples per second for 25 seconds (launch to apogee time will be far less than this). A suitable sampling resolution for this application is 12 bit resolution (1.5 bytes).

For a sampling of 8 channels at 20 samples per second at 12 bit resolution, 6000 bytes (6 Kbytes) of storage is required. The largest 8 pin EEPROM (in a DIL package) is capable of storing 8192 bytes. The spare capacity will even allow altitude data to be gathered on the descent, if the sampling of the other channels is switched off after parachute deployment.

The above specification allows the use of a simple PIC-based data acquisition system. The PIC CPU is an 8 bit RISC chip which will be run in this application at about 1 MIPS (MIP = Million Instructions Per Second).

The flight computer will be used for measuring the following parameters:

  1. Motor Parameters
  2. Airspeed
  3. Pressure
  4. Altitude
  5. Acceleration
  6. Temperature
  7. Acoustic levels

In addition to this, a commercially available altimeter, the Black Sky Research ALTACC, can also be carried in order to provide redundancy, and also to provide a second source of verifiable flight data (altitude and acceleration). It may also be used for primary recovery system deployment, with the parachute timers providing a redundant backup system.

The flight computer will be designed with the provision to add AV-TNG compatible telemetry as we develop it (AV-TNG probably will be ready in time for the first hybrid flight testings).

Flight Computer Specifications (Provisional)

CPU PIC 16C84 8-bit RISC
CPU Clock Speed 4 MHz
Processing Power 1 MIPS
Onboard Storage 8 Kbyte EEPROM - DIL packaged, 8-pin

Please note, this page is subject to change.

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Web page written by Richard Osborne.