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The South African Weather Service is equipped with 2 twin prop,
pressurized Aero Commander 690 A’s. These aircraft have been used
in weather modification experiments and also atmospheric chemistry
studies. The design of the Aero Commanders lends to use in harsh
environments, like severe icing and turbulence, warm temperatures,
high altitudes and long endurance. This makes them ideal for use
in atmospheric research.
The specifications of these aircraft are given in table a. The instruments
used on the aircraft are given in tables b,c,d and e. The aircraft
are capable of carrying 6 particle probes. One of the aircraft has
a high quality window for photography and radiometry. On board data
acquisition enables in flight decision-making. The aircraft is also
flexible and can be modified to carry almost any type of instrument.
Figure 1 shows a picture of ZS-JRA and figure 2 shows ZS-JRB.
a) Aero Commander
Technical Information
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| Aircraft length: |
44'4.25'' |
| Aircraft wingspan: |
46'6.64'' |
| Aircraft height: |
14'11.35'' |
| Maximum gross weight: |
10 250 lbs |
| Nominal operating altitude: |
25 000' to 28 000' AMSL |
| Maximum operating altitude: |
31 000' AMSL |
| Minimum speed: |
82 KTS |
| Nominal cruise speed: |
245 KTS |
| Maximum speed: |
260 KTS @ 25000' (as equipped) |
| Nominal sampling speed: |
100 to 180 KTS |
| Nominal rate of climb: |
1200'/min@ 18000' & 120KTS & 10000lbs |
| Maximum rate of climb: |
3400'/min@ 2000'MSL & 140KTS & 9000lbs |
| Endurance with maximum fuel: |
5.5 HRS @ 5000'MSL & 150KTS (no reserve) |
| Crew Capacity: |
1 to 4 (with instrument racks) |
| Cabin payload at maximum gross weight: |
1880lbs @ MAX ZERO FUEL WEIGHT |
| Cabin dimension: |
110.24'' x 47.24'' |
| Entrance door dimension: |
47'' x 26.5'' |
| Interior cabin passage way dimension: |
9.843'' BETWEEN SEATS |
| Standard equipment rack dimension: |
43.31'' x 19.69'' x 15.748'' |
| Floor mounting track width |
13.1583'' |
| Electrical power: |
28 VDC; 12 kW |
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2kW@ 220VAC, 60Hz |
|
1kW@ 115VAC, 60Hz |
|
4kW@ 115VAC, 400Hz |
b) Navigation
and Flight Characteristics
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| Parameter |
Technique |
Manufacturer |
Range*(resolution) |
| Latitude and longitude |
Global positioning system |
Trimble TNL2000 |
global |
| Position tracks |
Telemetry |
ESD |
120km |
| Ground speed |
Global positioning system |
Trimble TNL2000 |
global |
| True speed |
Derived from Pitot and Static pressure |
Rosemount |
10 to 300 KTS |
| Pitch, role and heading |
Synchro to digital |
ESD |
0 to 359 degrees (0.08 degrees RES) |
| Angle of Attack |
Variable resistance transducer |
Rosemount |
+‑23 degrees |
| Altitude |
Derived from Static pressure |
Rosemount |
0 to 30000 ft |
c) General Meteorological
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| Parameter |
Technique |
Manufacturer & Model |
Range*(resolution) |
| Total air temperature |
Platinum wire resistance |
Rosemount Model 102AU1AF |
-50 to +50 degrees Celsius |
| Static air temperature |
Reverse‑flow thermometer |
Inhouse |
30 to +50 degrees Celsius |
| Humidity |
Reverse‑flow humidity sensor |
Inhouse |
0 to 100% |
| Static Pressure |
Pressure Transducer |
Rosemount Model 1201FA1B2B |
0 to 32 Hg |
| Pitot Pressure |
Pressure Transducer |
Rosemount Model 1201FA1B2B |
0 to 5 psi |
| Parameter |
Technique |
Manufacturer & Model |
Range*(resolution) |
| Liquid water content |
Hot wire resistance |
Johnson & Williams |
0 to 2 and 0 to 6 g.m**‑3 |
| Liquid water content |
Hot wire resistance |
King / PMS |
0 to 5 g.m**‑3 |
| Liquid water content |
Particle measurement |
FSSP100 / PMS |
0 to 5 g.m**‑3 |
| Size spectrum of cloud particles |
Forward light scattering |
FSSP100 / PMS |
2 to 47 microns (15 channels)* |
| Images of cloud particles |
Diode occultation imaging |
OAP2D C / PMS |
25 to 800 micron Resolution 25 micron* |
| Images of precipitation particles |
Diode imaging |
OAP2DP / PMS |
Resolution 200 micron* |
e) Data acquisition
cards
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| Card type |
Function and Resolution |
Quantity |
Manufacturer |
| Timer and Keypad |
Sample rate and hot keys |
1card |
ESD |
| Analog to Digital |
16 channels, 16 bit, Bipolar (+‑10V) |
2 cards |
ESD |
| Synchro to Digital |
3 channels, 16 bit |
2 cards |
ESD |
| PMS 1D |
15 channels & activity & Total Strobes |
2 cards |
ESD |
| PMS 2D |
Image Acquisition |
2 cards |
ESD |
| Serial 232/422 Port |
GPS interface |
1 |
ESD |
*all particle sizes refer to maximum particle dimension
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Figure 1. ZS-JRA in flight
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Figure 2. ZS-JRB in flight
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