Model 0858Multi-Function Probes

SENSOR SYSTEMS

PRECISE PNEUMATIC MEASUREMENTS

> Pneumatic Measurements of Local Flow Angles up to 45 Degrees

> 0.2 Probe Measurement Accuracy

DESCRIPTIONThe Model 0858 is a fuselage or boom-mounted all-weather Angle of Attack (a) and Angle of Sideslip (b) probe allowing precise pneumatic measurement of local flow angle.

SPECIFICATIONSElectrical Heater Voltage: 115 VAC, 400 Hz or 28 VDCHeater Power: 370 Watts maximum

Environmental Vibration: MIL-STD-810C, Method 514.2, Curve J, Equipment Category b.1

NORMALIZING (METHOD 1)Of the two normalizing methods, the recommended and most widely used (Method 1) is to use the ports on the sensing head to generate normalizing pressure signals. This method offers the definite advantage of eliminating special calibrations (as in Method 2) to account for differences in local conditions between the sensor and a remote point for qCN and pitot pressure measurements.

The differential pressure (Pa1 Pa2) is proportional to the product of qCN times a1; where qCN equals local pitot pressure minus local static pressure, and a1 equals local angle of attack. Depending upon the parameters desired, the sensing ports may be configured as follows:

Angle of Attack ConfigurationFigure 1 shows two ports, Pa1 and Pa2, located in the angle of attack plane. A third port, P3, is located in the center of the sensor head to provide a local pitot pressure source. The two ports, P4, are manifold together to provide an approximate local static pressure. Angle of attack (a1) can be determined using two differential transducers (or other instruments) which measure the outputs Pa1 Pa2 and P3 P4, according to the relationship:

Pa1 Pa2 a1 = ___________ (K1 is a sensitivity coefficient) K1 (P3 P4)

Angle of Sideslip ConfigurationAs shown in Figure 2, this same configuration can be used to measure angle of sideslip (b1). By rotating the sensor

head 90 about the axis of symmetry, the differential ports, Pa1 and Pa2, now become located in the horizontal plane and are labeled Pb1 and Pb2. The equation then becomes:

Pb1 Pb2 b1 = __________ K1 (P3 P4)

Angle of Attack and Sideslip ConfigurationBoth angle of attack and angle of sideslip can be measured with a single probe configured as shown in Figure 3. In

this case, the ports, P4, are replaced by Pb1 and Pb2, (not manifolded together) with a correction term which averages the sideslip pressure Pb1 and Pb2, instead of P4. Output signals (Pa1 Pa2), (P3 Pb1), and (Pb1 Pb2), are used in the following equations:

Pa1 Pa2 a1 = ________________________________ K1 [(P3 Pb1)+ (Pb1 Pb2)] 2 Pb1 Pb2 b1 = ________________________________ K1 [(P3 Pb1)+ (Pb1 Pb2)] 2NORMALIZING (METHOD 2)It is possible to use another source such as a pitot-static tube to measure qc1 for normalizing. The equations for

MULTI-FUNCTION PROBES

Figure 1:Angle of Attack Configuration

Figure 2:Angle of Sideslip Configuration

Figure 3:Angle of Attack & Sideslip Configuration

Weight per unit is 1.5 pounds maximum

Weight per unit is 1.5 pounds maximum

All dimensions in inches

angle of attack and/or sideslip are:

Pa1 Pa2 Pb1 Pb2 a1 = _________ b1 = _________ K2 (qc1) K2 (qc1)

SENSITIVITY COEFFICIENTSA further advantage of Method 1 is shown in comparing the two sensitivity coefficients (K1 and K2). The coefficient is a function of Mach number and remains constant for subsonic and supersonic speeds. Figure 4 shows that K1 is greater than K2 and is constant over a broader Mach range; changing substantially less than K2 through M = 1.0. Also, K1 is essentially constant for angles of up to 45 compared to a range of about 12 for K2.

FOR ADDITIONAL INFORMATIONTo learn more about the Model 0858 Multi-Function Probes, call Goodrich at 952 892 4000.CONFIGURATION DRAwINGS

Figure 4: Comparison of Sensitivity Coefficients

K1(METHOD 1)

K2(METHOD 2)

Goodrich Sensors and Integrated Systems14300 Judicial RoadBurnsville, MN 55306-4898USATele: +1 952 892 4000Fax: +1 952 892 4800

www.goodrich.com/sis

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