Company Confidential

ADP‑55 Smart Air Data Boom

The ADP‑55 of Simtec is a highly integrated, smart air data boom with an integrated and regulated
heating and drainage system. The system provides a full set of calibrated and aerodynamically
corrected air data in a single probe at rates of up to 100Hz over an RS‑485 interface. ARINC‑429
and CANaerospace data interface modules are available as well.

The purpose of this air data system is to provide a flying vehicle with valuable information about
the vehicle’s speed, its angle of attack and side-slip, the static pressure and temperature of the
ambient air. Derived parameters like pressure altitude, true airspeed, Mach number and static
temperature are computed as well.

Many propeller aircraft and UAVs fly slower than jet aircraft and require special pressure and
temperature sensors and adapted electronics to account for the much lower impact pressure and
the high dynamics of the vehicle. The system has a very low transport delay. Furthermore the ADP
‑55 has a TAT sensor that is optimized to work even at very low airspeed.

Key Features
– Self-contained multi-hole air data boom
– Measures static pressure, impact pressure, angle of attack, angle of side-slip and total
temperature in a single device
– Outputs fully calibrated and aerodynamically corrected air data at up to 100Hz
– Made of stainless steel and aircraft grade aluminium
– Integrated and regulated heater
– Drainage system
– Less parts compared to a conventional system
– Low transport time and high accuracy
– Low total cost of ownership
– Designed and tested in the wind-tunnel
– RS-485 interface compatible with Swiss Air Data line of Air Data Systems
– Easy configuration of output rate, digital filters, baud-rate via maintenance software

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Target Market
– Best solution for Tactical UAV, MALE UAV, Rotary Wing UAV
– Remotely Piloted Aircraft (RPA)
– High Altitude Pseudo Satellites (HAPS)
– Flight Testing (including eVTOL, helicopter)
– Research Aircraft

System Overview
The ADP‑55 heated air data boom provides calibrated and aerodynamically corrected pressure,
temperature and air data over the RS-485 interface. Raw but digitized measurement data is read in
over the RS‑485 interface from the heated air data probe (ADP) and processed by the real-time
measurement computer (RTMC). The maintenance interface is used to update calibration values,
set output frequency and other values.

Figure 1. Overview (RS‑485 data interface)

The ADP‑55 uses silicon based pressure sensors individually calibrated over the full temperature
range of -55°C … +80°C (power up above -40°C) to provide very accurate data.

Angle of attack and angle of sideslip data is measured with a five-hole probe without friction, very
quickly and accurately. The following steps describe the basic functionality of the 5-hole probe:

1. The air-stream is picked up at the 5-hole probe and fed to the integrated pressure sensors.
Temperature is picked up by the TAT sensor
2. The sensor signals are amplified and digitized by a microprocessor based electronic circuitry
(24 bit A/D conversion).
3. The digitized air data is sent via a RS‑485 interface to the real-time measurement computer
(RTMC).
4. The RTMC performs the sensor calibration and applies aerodynamic corrections. Then the
embedded microprocessor computes data like altitude, airspeed, etc. from the sensor data.
5. Data labels are sent via a RS‑485 interface to the FCC for further processing.

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The five-hole probe technology provides the following important features:

– Integrated correction of impact and static pressure at angle of attack and angle of side-slip
– For highest accuracy and frequency response the sensors and sensor digitizing electronics are
directly integrated in the boom thus minimizing tube length to a minimum.
– As the sensors and sensor electronics are adapted to the flight envelop of the flight vehicle the
highest accuracy is achieved

Heater
The integrated heating electronics regulates the temperature of the probe within a narrow band
of temperature usually at +40°C. Maximum power of the heater is 240 Watt between 22…28 VDC.
Both the maximum temperature and the maximum power are configurable. Status labels provide
detailed information on the data interface. Command labels are used to switch the heater on and
off during flight or to put the heater into auto mode. The heater features a surge protection
above 30VDC to protect the internal electronics.

Drainage
The total pressure orifice on the tip of the probe is equipped internally with a cover plate like
device and a drain hole to be self-draining in flight. The drain holes are designed in such a way that
the error on the stagnation pressures is very small. This error is calibrated and automatically
correct by the air data computer (ADC). The static pressure ports are designed so that water drains
off at the bottom of the tip.

Built-In Tests
Memory, interfaces and other components are tested at start-up. Sensors and electronics are
continuously monitored. Errors are enunciated on the data port.

Maintenance and Test Software

PC-Software to configure, maintain and test the ADP‑55 can be downloaded from
https://www.swiss-airdata.com.

Specification
Table 1. Measurement Range and Accuracy
Property Value Details
Static Pressure 45 hPa … 1'080 hPa
Range -1'800 ft … 69'000 ft
Dynamic Pressure ±16 hPa dif ~95 KCAS
Range ±30 hPa dif ~135 KCAS
±75 hPa dif ~210 KCAS
±150 hPa dif ~295 KCAS
Other ranges on request Max. Mach 0.96

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Property Value Details

AoA and AoS Range ±30° Optimized accuracy for smaller
ranges. Special applications up to
±45° with reduced accuracy. At high
airspeed the range is usually
reduced to gain some accuracy at
low airspeed. Ask for details.
TAT Range <85°C [1]
Pressure-Accuracy larger of 0.1%FS and ±1 Pa [2] FS: Full Scale, [3]
Temperature-Accuracy ±1°C

Table 2. Data Rate, Resolution, Delay, Bandwidth

Property Value Details
Output Rate 100, 50, 25, 20, 10, 5, 1Hz
Transport Delay <25ms Valid at 100Hz, 230'400bps
Resolution 24 bit At pressure level
Bandwidth 25 Hz [4] Cut-off frequency at -3dB
Start-Up Time <1 sec

Table 3. Data Labels

Property Value Details
Basic Data Labels Static Pressure (Ps) Note that all data-labels are
Dynamic Pressure (Qc) aerodynamically corrected up to
Angle of Attack (AoA) ±30°, the system is comparable to a
Angle of Sideslip (AoS) swivel-head air data boom but
Total Air Temperature (TAT) without moving and delicate parts.

Computed Air Data Pressure-Altitude (Hp)

Labels Barometric-Altitude (Hb)
Calibrate Airspeed (CAS)
True Airspeed (TAS)
Mach-Number (M)
Climb-Rate (CR)
Static Air Temperature (SAT)
Duty Rate Heater (DTR)
Heater Temperature (HTR)
Heater Current (CUR)
Uncorrected sensor-pressure and
sensor temperature data labels

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Table 4. Environmental Performance

Property Value Details
Temperature Range -40°C..+80°C Power Up
-55°C..+80°C Operating, fully temperature
-55°C..+80°C calibrated
Storage
Load Factor ±10g by analysis, many test flights with
±6g and roll rates of 360°/s
performed
Media Compatibility Clean Air Non-condensing and non-corrosive
gases

Table 5. Mechanical
Property Value Details
Mass RTMC 0.250kg Add 0.030kg for ARINC-429 or
CANaerospace module
Mass Probe 0.650kg
Materials The tip of the probe is build from stainless steel and aviation grade
aluminium. The RTMC box is built from aviation grade aluminium.
Mounting 6x M4 screws, for details see drawings
Dimensions For dimensions see CAD drawings
of ADP‑55

Table 6. Electrical
Property Value Details
Data Interface RS-485 Full-Duplex ARINC‑429 or CANaerospace
module available (replaces RS‑485
data interface)
Maintenance Interface RS-232
Power Supply 9..32 VDC Air Data Computer only
Power Consumption 210 mA @ 9V Air Data Computer only
75 mA @28 V
Heater Power Max. 240 Watt (regulated) Max. down to 22V, automatic shut-
down above 30V. High power is
used at low ambient temperature
and high airspeed only.

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Property Value Details

Baud-Rate 57'600 bps
115'200 bps
230'400 bps
460'800 bps
Connector RTMC DSUB-15 (Deltron 15 pins, male and female, for pin-
DTS15PY/2M85UN) assignment see ICD
DSUB-15 (Deltron
DTS15SY/2M85UN)
Connector Probe MIL-DTL-38999 III (20WB35PN) 13 pins, for pin-assignment see ICD

Ordering Information
Table 7. Part-Numbers
Part-Number Details Description
SIM-4B0-7B7 Air Data Probe with RTMC Includes probe, RTMC, mating plugs
and software.
Configuration: RS-485, ARINC-429
or CANaerospace
Options: Heater Module, Transonic
Module and TAT-Removed
SIM-53A-8A2 Air Data Probe Replacement part
SIM-E4A-B76 RTMC Box Replacement part
SIM-2A8-03A Installation Brackets
SIM-20F-215 Tip Cover Ground Support Equipment (GSE)
SIM-20F-2E3 RTMC-to-USB Converter Cable GSE
Assembly
SIM-906-060 Pressure Test Adapter pt/ps GSE
SIM-3FB-ED5 Pressure Test Adapter qc/AoA/AoS GSE
SIM-1FD-A56 Arinc-429 to USB-Converter Box GSE

RoHS and REACH

RoHS: Simtec’s safety critical aerospace products are excluded from the scope of the RoHS
Directive.

REACH: Simtec PCBs (printed circuit boards) are soldered with leaded solder. Lead (CAS-No. 7439-
92-1) is listed as a substance of very high concern (SVHC). When used as intended, these products
are not hazardous to health.

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Price, Availability and Lead Time

Call factory for details. The pitot-static system is built on order. Depending on user requirements, it
takes between 6 to 8 weeks to build, calibrate and test the system.

Service and Support

Service and Repair: Should any damage occur during shipping, handling, or misuse by the user,
Simtec is able to service it.

Consultation: Technical consultation can be obtained from Simtec if expertise is needed for the
integration of the air data system into the aircraft, during flight-testing or post processing of data.

Contact Information
Simtec AG
Gewerbestrasse 7/7a
CH 4147 Aesch BL
SWITZERLAND

Tel.: +41 61 703 0222

info@swiss-airdata.com
http://www.swiss-airdata.com

16.04.2022/R4
Copyright © 2022, Simtec AG, All rights reserved. Information in this document is subject to change without notice.

[1] Limit will be increase on new revision.

[2] Accuracy is the sum of repeatability, hysteresis, thermal effects in the specified temperature range, the calibration is traceable to
DAkkS.
[3] By periodic nulling (e.g. every 6-12 month) the accuracy of the airspeed and angular errors can be improved. The airspeed and
angular errors are mostly offset errors, offset errors can be nulled easily at zero airspeed with the help of the maintenance software or
directly via FCC-commands.
[4] To be verified on latest revision

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