302 Direct Digital Variometer Manual ______________________________________ 302 DDV TM Cambridge Aero Instruments, Inc. 6047 Executive Centre, Suite 1 Memphis, Tennessee 38134 (901)382-1352 voice (901)382-1351 fax www.cambridge-aero.com 302 Direct Digital Variometer Manual Firmware Version 2.6 Firmware by Phil Schlosser; Text by Dave Ellis The IGC approval document is on the CD supplied with the instrument. WARRANTY All Cambridge Aero Instruments, Inc., products are guaranteed against defects for TWO YEARS from date of original purchase, when used in gliders. The warranty is limited to faulty workmanship and/or materials. The unit must be returned to the factory or to an authorized repair station. This warranty is void if failure is due to accident, mishandling, or repairs performed by unauthorized persons. This warranty is given in lieu of all other warranties, expressed or implied. NOTICE This device is not to be relied upon for navigation in flight. This device is designed only to be an aid to navigation performed by using required training and methods without this device. 302 DDV Manual - February, 2003, July 2007 – Cambridge P/N MA-013 Page 1 of 26 pages 302 Direct Digital Variometer Manual Table of Contents Section Page # 1. Introduction 3 2. Installing the Instrument 4 2.1 Instrument Panel Mounting 2.2 Pneumatic Tubing Connections 2.3 GPS Antenna Installation 6 2.4 Outside Air Temperature Probe Installation 2.5 Power and Logic Wiring 7 3. The DDV Operator’s Guide 9 3.1 Instrument Controls 3.2 The LCD Screens 3.3 The Power-ON Screens 11 4. Configuring the DDV using the Utility Program 12 4.1 Introduction 4.2 Installing the Utility program 4.3 Running the Utility program 4.4 Utility program troubleshooting 19 5. Flight Recording with the DDV 19 5.1 Introduction 5.2 Transferring flight logs from the DDV 20 6. Troubleshooting your Cambridge DDV system 20 7. Flying with the DDV 22 8. Technical Specifications 23 Appendix A. DDV Firmware Upgrades 23 Appendix B. 300-series data communications 25 Appendix C. 300-series installation for 2-seat gliders 26 302 DDV Manual - February, 2003, July 2007 – Cambridge P/N MA-013 Page 2 of 26 pages 1.0 Introduction The Cambridge 302 Direct Digital Variometer (DDV) has sensors for altitude, airspeed, acceleration, engine noise level, and temperature. It gives visual and audio climb and speed-to-fly information; and it displays climb rate, average climb rate, altitude and MacCready setting. The 302 DDV includes an integral GPS receiver that generates IGC-approved Secure Flight Logs. The instrument supports other Cambridge 300-series products such as the 304 Pocket-NAV graphic display, and the 303-NAV navigation display. Calibration and performance adjustments are firmware based. The DDV is altitude and temperature compensated. Flash memory is used for firmware as well as flight logs. Firmware upgrades are distributed via the Cambridge web site on the Internet. There are 4 versions of the DDV: 302M Metric dial plate (M/S) 302E English dial plate (Knots) 302M-MG Motorglider (M/S) 302E-MG Motorglider (Knots) The Cambridge DDV is supplied with ALL parts necessary for installation as follows: 1. A 302 Standard Power Cable (CAA-114) 2. The white-tipped Outside Air Temperature (OAT) probe (CAA-115) 3. The 6 foot (2 meter) beige serial data cable (HA-349) 4. The plastic laminated Operator’s Card (MA-012) 5. This User’s Guide (MA-013) 6. A CD-ROM with all programs and documents in PDF form. 7. Spare power cable (CAA-116) 8. A small screwdriver for the plug and connector strip (TL-001) 9. 1 meter of soft silicone rubber instrument tubing (WA-044). 10. Three “Tee” (HA-100) and three “Straight” (HA-101) tubing connectors 11. A package of 15 small tie wraps 12. A GPS antenna with SMC connector (HA-435) (302 only) 13. A remote speaker (CAF-031) (302 Motorglider version only) The DDV supports an auxiliary NIMH battery pack (CA-117). During normal flight the instrument keeps the auxiliary battery charged. If the glider’s main battery fails, the auxiliary battery powers a complete Cambridge 300 system for more than two hours. 302 DDV Manual - February, 2003, July 2007 – Cambridge P/N MA-013 Page 3 of 26 pages 2. Installing the Cambridge 302 Direct Digital Variometer Please don’t rush to put this instrument into your glider. It is much, much more than a variometer. You will benefit from experimenting with the instrument before flying with it, so we have supplied you with a spare power connector. Connect the instrument to any 12-volt power source so you can play with it at home. Turn the TV set off for several evenings and make friends with your new instrument. The Cambridge DDV needs to be configured for glider polar, measurement units, and pilot preferences. This is done with 302 Utility Programs using your PC or your Windows CE PDA. Section 4 of this manual has instructions for using the Utility program The DDV can also be configured from the 303-NAV LCD display. 2.1 Mounting the instrument in the glider panel The instrument fits any standard 57-mm (2.25”) round panel opening. There is an adapter for mounting the instrument in an 80-mm (3.12”) hole. The knob shaft at the lower left of the instrument face will fit through the standard instrument mounting screw hole. To remove the knob for installation, snap the knob cover off with your fingernail and loosen the screw. The knob will slide off the shaft. When re-installing the knob, make sure it can be pushed in enough to actuate the momentary pushbutton switch. Be careful to center the shaft in its instrument panel hole. The push-button switch won’t work properly if the shaft rubs on the panel. 2.2 Pneumatic Tubing Connections Cambridge DDV performance is limited by behavior of the glider’s pressure sources, rather than by quality and calibration of its pressure sensors. Good performance will be obtained with safe, conservative choices for pressure sources. Performance optimization requires that you, the pilot, understand the issues and be willing to experiment with different sources of static and pitot pressure. 2.2.1 Connections for Airspeed Measurement Airspeed is computed from “dynamic pressure”, the difference between pitot and static pressure. The upper two ports sense dynamic pressure. Connect the instrument’s Static Port (top fitting) to the same source that supplies static pressure to the glider’s mechanical Air Speed Indicator (ASI). Connect the Pitot Port (middle fitting) to the same source that supplies pitot pressure to the glider’s ASI. Proper DDV function depends critically on correct airspeed measurement. It is REALLY important that pitot and static pressure connections are correct. Indicated Airspeed (IAS) is shown on DDV Screen #10 (See Section 3). During flight, make sure that your mechanical ASI and the DDV IAS readings agree. If you see a negative airspeed, you have reversed the pitot and static connections. If DDV IAS values seem really weird, check the airspeed display units. (Display units are discussed in Sections 4.3) 302 DDV Manual - February, 2003, July 2007 – Cambridge P/N MA-013 Page 4 of 26 pages 2.2.2 Connections for Altitude Measurement The DDV has two independent barometric pressure sensors that measure altitude. The altimeter reading shown on the instrument’s HOME screen comes from a pressure sensor with no pilot-accessible port. This Altimeter also generates the Barograph trace for DDV Flight Logs. Note: Flight Log Altitude is based on the standard atmosphere sea level barometric pressure of 29.92”Hg (1013.2mBar) The second barometric pressure sensor is used exclusively by the variometer. The fitting for this sensor (TE/Static) is at the bottom of the instrument’s rear panel. For diagnostic purposes, altitude measured by this sensor is shown as [Pr Al] on Screen #6 (See Section 3). To be useful in a modern glider, a variometer must be Total Energy Compensated (TEC). This is because gliders are wonderfully efficient at converting speed into altitude and vice-versa. A non-TEC vario goes crazy during pull-ups into thermals. The glider’s Total Energy is the sum of potential energy (altitude) and kinetic energy (airspeed). A TEC vario measures how quickly total energy, rather than just altitude, is changing. A vario with good TE-compensation is insensitive to “stick-thermals” caused by the pilot. A Total Energy (TE) probe is an air pressure source that incorporates both kinetic and potential energy measurement. See any textbook on gliding for an explanation. Section 2.2.3 explains how to connect the DDV to a TE-Probe. The Cambridge DDV measures kinetic energy (derived from its airspeed sensor). It can achieve Total Energy compensation by electronically adding potential energy (altitude) and kinetic energy (airspeed). Section 2.2.4 explains how to connect the DDV so TE compensation is done electronically without using the glider’s TE probe. 2.2.3 Total Energy Compensation using the TE-Probe (Recommended!) Connect the DDV TE/Static port to the glider’s Total Energy (TE) probe. The probe provides TE compensation. This configuration REQUIRES that you set the TE percentage shown on Screen #9 to ~0%. (No electronic TE compensation). 2.2.4 Electronic Total Energy compensation. Connect the DDV TE/Static port to the glider’s Static pressure source. In this case, the Airspeed Static Port and TE/Static port are connected together. This configuration REQUIRES that you set the TE percentage shown on Screen #9 to ~100%. (Complete electronic TE compensation) 302 DDV Manual - February, 2003, July 2007 – Cambridge P/N MA-013 Page 5 of 26 pages 2.2.5 Using Prandtl Tube or “Triple Probe” pneumatic sources A Prandtl Tube or “Triple Probe” is an excellent source of both Static and Pitot pressures.