1. P-Static Effects Testing
LORAN PROJECT TEAM MEETING
July 30-31, 2002
Dr. Robert Lilley
Illgen Simulation Technologies, Inc.
/ x 204

2. Illgen FY-02 funding awarded
Task 2 Status
Illgen FY-02 funding awarded
Subcontractor TCO Manufacturing (Bob Truax)
Completion of testing, delivery of 50 kV power supply
FAATC on-site ground calibration, electrostatic survey
Active discharger shakedown, preparations for flights
Prepared to support data reduction, reporting
Meeting this week with FAATC project team
Take LORIPP questions/suggestions into account
Test plan, schedule review and update

3. Review of lead-in p-static work
Ground-based tests, 1999
Illgen
TCO Manufacturing (Bob Truax)
Ohio University Avionics
Locus
Megapulse
Excerpts from project report
To illustrate LORIPP discussion July 24-25, 2002

4. What is p-static? The process involves high voltages, low currents
P-static noise is the electrical by-product of the arrival and departure of ions from an airframe in flight.
Ions are produced during collision of airframe with neutral rain or ice particles, or flight in charged airspace (near thunderstorms). Once charged, the ions can create noise in three ways:
Corona - Departure of ions from trailing edges in the slipstream
Corona threshold is “tuned” by the geometry of the airframe
“Dischargers” use small curvature radii to reduce threshold
Streamers - Ion paths across dielectric surfaces (radomes, windscreens, composites)
Reduced by conductive coatings, other techniques
Arcs - Discharge between unbonded airframe parts charged to different potentials
Can be energetic, but less continuous than corona or streamers.
The process involves high voltages, low currents
kV on GA aircraft
Tens to hundreds of uA discharge current

5. calibration test in hangar. Final tests were performed outside.
Test aircraft with flood fixtures at leading edges and showing acrylic tire pads and HV supply.
Note Loran-C whip antenna on top of cabin, and Locus loop antenna further back on top. Initial
calibration test in hangar. Final tests were performed outside.

6. Fixtures are at rear of wings, rudder and stabilator
View of ion collector fixtures at trailing edges of airframe.

7. Tail tip discharge monitor
Current
Metering
Panel:
uA Meter
Array
Rudder
Rt Tail
Lt Tail
Lt Wing
Rt Wing
Rt Pad
Lt Pad
Nose Pad
Total
Tail tip discharge monitor
Ion collection fixtures
3 Ion flood fixtures with corona ball and ignition lead
Variable HV
Power
Supply
Acrylic pads with leakage guard bands to isolate tires

8. Locus H-field Antenna Tests Under Precipitation Static Conditions
Test performed by Locus, Inc / Megapulse, Inc. / Illgen Simulation Technologies, Inc / at the Avionics Engineering Center, Ohio University. November 1998.
Vmax
Vmax
SNR
Time Difference
Time Difference from Seneca, N.Y. station tracked from Athens, Ohio
Vbaseline
Vbaseline
Vbaseline - no charge on airplane
Vmax - maximum charging, 27 KV and 51 uA

10. No charging on the airframe.
15kV, 9.3 uA discharge;
note the distinctive
character of the corona discharge
at this repetition rate. Noise amplitude
is increased some 27 dB.
21.4 kV, 40.8 uA discharge.
Overall corona noise is now
about the same, but its spectral content
character is different.
Spectra at the output of the Locus preamplifier stage
Initial runs, inside hangar, e-field antenna attached.
Wideband analog tape recordings were also made.

11. Conclusion/Recommendation
Illgen and TCO prepared to support FAATC tests
Not principally an integrity issue; one of availability
P-static test program modifications
Absolute vs. relative numbers
"The system is approved for enroute and terminal IFR, using e-field antennas. It will only get better with h-field ones."
To what extent can we build on that present certification?
Can the present FAATC test program "get absolute"?
Wideband data collection to be added?
Better characterization of noise content