MGL Avionics Stratomaster Vega ASI-4 User manual

Introduction
The ASI-4 is a 2 1/4” sunlight readable instrument that provides a wide range airspeed indication in both digital and
analog tape formats Airspeed is based on the pressure generated by a pitot tube system and a static port is provided as
well for use by high speed aircraft In addition, the ASI-4 provides a flight timer since takeoff and records the maximum
airspeed reached
Airspeed can be indicated in statute miles per hour (mph), kilometers per hour (km/h) or nautical miles per hour (kts) The
analog airspeed tape can be scaled according to the aircraft’s flying speed range and ranges for Vs0, Vs1, Vfe, Vno and
Vne can be set The ASI-4 also provides a programmable Vs and Vne airspeed alarm output ASI sensitivity can be
calibrated by the user to cater for errors caused by pitot tube placement
The ASI-4 instrument measures airspeed from 16mph to 250mph and is well suited to slower aircraft due to very good
sensitivity and linearity at low air speeds
1 Features
•Large 1.8” high resolution 160x128, sunlight readable, wide viewing angle, 1000 cd/m2 T T LCD display
• Measures airspeed from 16mph to 250mph and is well suited to slow aircraft due to very good sensitivity
and linearity at low air speeds
• Includes a flight timer since takeoff
• irspeed units can be set to miles per hour (mph), kilometer per hour (km/h) or nautical miles per hour
(kts)
• nalog tape with programmable ranges for Vs0, Vs1, Vfe, Vno and Vne
• Contains a programmable Vs and Vne airspeed alarm output
• Records maximum airspeed reached in permanent memory
• Standard 2 1/4” aircraft enclosure (can be front or rear mounted)
• Rotary control plus 2 independent buttons for easy menu navigation and user input
• Wide input supply voltage range of 8 to 30V DC with built in voltage reversal and over voltage protection
for harsh electrical environments
• 1 year limited warranty
Vega SI-4
irspeed Indicator ( SI)
Operating Manual – English 1.00

Vega SI-4 Operating Manual Page 2
2 SI-4 Layout
3 Main Display
F2 / Down Button:
Menu system: Softkey button
Sunlight readable color
graphic display:
Backlight can be adjusted in the
menu system
Rotary Control (Up/Down) & Enter Button:
Press the rotary control during the normal display screens to access the menu system Rotate anti/clockwise for
up/down menu scrolling Rotate the rotary control during the normal display mode to view the Max Values display
F1 / Up Button:
Menu system: Softkey button
Normal Display: Start / Stop the
flight timer (Manual flight only)
2 1/4” enclosure
Can be front or rear mounted
Airspeed unit
Digital airspeed
Airspeed tape
Duration of flight since takeoff
Vso (Min safe speed, landing)
Vs1 (Min safe speed, normal)
Vfe (Max flap speed)
Vno (Max maneuvering speed)
Vne (Max exceed speed)

Vega SI-4 Operating Manual Page 3
3.1 Maximum irspeed display
This display can be accessed by rotating the rotary control during the normal display
mode Press the F1/Up button when the max values display is showing to reset the
maximum values to the current airspeed
3.2 Start / Stop flight display
Press the F1/Up button during the normal display mode
to manually start/stop a flight This key is only active if
the ASI-4 is setup to select the manual flight option
under the “TIMERS” setup menu
Note: The maximum airspeed is stored in non-volatile
memory and is recalled on power-up.

Vega SI-4 Operating Manual Page 4
4 Menu System
Press the rotary control button during the normal display mode to enter the menu system Use the rotary control to
navigate through the menu system
4.1 Exiting the menu system
Press the F1/Up button to exit the menu system when the “EXIT” soft key is shown All changes made during navigation
of the menu system will be saved in non-volatile memory upon exiting The instrument will not save any changes if you
remove power before exiting the menu system
4.2 SI Setup ( irspeed Setup)

Vega SI-4 Operating Manual Page 5
Zero ASI Sensor:
This setup allows your instrument to measure the zero airspeed reading of the airspeed sensor and set a calibration value
internally for this This is equivalent to some mechanical airspeed indicators that have an adjustment to set the needle to
zero when the aircraft is not moving You would use this function occasionally if you see an airspeed reading when the
aircraft is at rest This may be caused by aging of the built in pressure sensor or related electronics When this function is
performed make sure that there is no air flow into the pitot tube as this would result in an incorrect internal calibration
ASI Unit:
Select if you want the ASI to be displayed in mph (statute miles per hour), km/h (kilometers per hour) or kts (nautical miles
per hour)
ASI Filter:
This function can be used to select the signal filter time constant Selections are "NONE", “FAST” or “SLOW” This
selection influences the rate at which your ASI can change its reading If you have an installation that suffers from strong
turbulence at the pitot tube, select “slow” If you have a very clean airflow in front of the pilot tube you can select “fast”
which will give you a faster response to airspeed changes
ASI Span:
Select the maximum airspeed that you want the airspeed tape to display This can give you increased display resolution
ASI In View:
Adjust this setting to set the amount of tape to view For example, setting this value to 30% and your "ASI SPAN" to 250
will result in the tape showing 75 on the display at a time
Vne Speed: (Max Exceed Speed)
Enter you maximum speed you aircraft should not exceed
Vno Speed: (Max Maneuvering Speed)
Enter your maximum maneuvering speed
Vfe Speed: (Max Flap Speed)
Enter the maximum speed that is permissible with the flaps extended
Vs Speed: (Min Safe Speed, Normal)
Enter your minimum safe speed for normal flight of your aircraft
Vs0 Speed: (Min Safe Speed, Landing)
Enter your minimum safe speed for landing your aircraft
Vs Alarm:
This enables or disables Vs Alarm
Vne Alarm:
This enables or disables the VNE alarm

Vega SI-4 Operating Manual Page 6
Cal:
During the factory calibration a factor has been determined and entered here that will give you accurate airspeed,
provided your pitot tube is not influenced by pressure effects caused by airflow around your airframe The calibration is
displayed in % of the reading, you can increase or decrease the reading if required to help cancel out under or over
reading of the airspeed indicator on your aircraft The original calibration factor has been written onto the back of your
instrument
4.3 Timers Setup
FLIGHT:
Select whether you want the ASI-4 to automatically detect a flight or whether the pilot must press the F1/Up button to
start/stop a flight We recommend you select automatic flight detection
T/O AIRSPEED:
This menu option is only shown if the “DETECT” flight mode is selected Enter the takeoff airspeed threshold that you
want the flight timer to start incrementing

Vega SI-4 Operating Manual Page 7
4.4 MISC Setup (Miscellaneous Setup)
Backlight:
Select this menu option to adjust the backlight brightness
Security Setup:
Select this menu option if you want to password protect the menu system
Information:
This menu option displays information about the unit

Vega SI-4 Operating Manual Page 8
Default Settings:
Select this menu option to reset all the settings to factory defaults
4.5 DC Values
This menu displays the ADC value that have been read from the pressure sensor
5 Loading factory default settings
Press and hold the F1/Up button and rotary control during power up to load the pre-
programmed factory default settings The following screen will be displayed:
Factory default settings can also be loaded in the Miscellaneous setup menu

Vega SI-4 Operating Manual Page 9
6 Error Messages
Unit settings CRC error Load default settings to restore to factory defaults If the error
message still persists then it could possibly be a non-volatile memory failure in which
case the instrument will then have to be returned to the factory
Calibration constants CRC error The instrument could possibly have a non-volatile
memory failure in which case the instrument will then have to be returned to the factory
Max Values CRC error Load default settings to restore to factory defaults If the error
message still persists then it could possibly be a non-volatile memory failure in which
case the instrument will then have to be returned to the factory
7 SI-4 Specifications
Operating Temperature Range -10ºC to 60ºC (14ºF to 140ºF)
Storage Temperature Range -20ºC to 80ºC (-4ºF to 176ºF)
Humidity <85% non-condensing
Power Supply 8 to 30Vdc SMPS (switch mode power supply) with built in 33V over
voltage and reverse voltage protection
Current Consumption Approx 73mA @ 13 8V (backlight highest setting), 33mA @13 8V
(backlight lowest setting)
Display
1 8” 160x128 pixel active matrix TFT display
1000 cd/m2
Sunlight readable with anti-glare coating
LED Backlight is user configurable
larm Output Open collector transistor switch to ground
Maximum rating 0 5A
Dimensions see Vega series dimensional drawing
Enclosure 2 1/4” ABS, black in color, front or rear mounting Flame retardant
Weight Approx 120 grams (Instrument excluding cables)
Non-volatile memory storage 100000 write cycles
irspeed DC resolution 12 bit
irspeed range 16mph to 250mph
irspeed resolution 1 mph
Measurement accuracy +/-1% at 85mph nominal

Vega SI-4 Operating Manual Page 10
8 Operating the alarms
The alarm output can be used to switch an external alarm indicator The external alarm switch is an open collector
transistor switch to ground with a maximum rating of 0 5A DC It is possible to wire the alarm contacts of several
Stratomaster instruments in parallel should this be desired To avoid false activation of the alarms, the alarm function is
only active 10 seconds after the instrument has powered up
9 Firmware Upgrading
The ASI-4 can be upgraded in the field by connecting the RS232 port to a PC and running the firmware update program
Note that only the RS232 port can be used to upgrade the firmware.
Please see the Vega firmware upgrading document for more information.
10 Cleaning
The unit should not be cleaned with any abrasive substances The screen is very sensitive to certain cleaning materials
and should only be cleaned using a clean, damp cloth
Warning: The ASI-4 is not waterproof, serious damage could occur if the unit is exposed to
water and/or spray jets

Vega SI-4 Operating Manual Page 11
11 Installation
Connect a pitot tube to the “pressure port” and if required connect the static port Most small aircraft such as ultralights or
microlights do not require a connection to a static port In these cases, simply leave the static port open Ensure however
that the static port does not receive pressurized air due to the forward movement of the aircraft Be especially critical of
your pod or panel if you do not use a static port Any build up of a pressure differential due to ram air or suction can lead
to large errors of the indicated airspeed Static ports are usually mounted at a strategic position on the rear side of the
aircraft fuselage for faster, pressurized aircraft
Suitable connection hose for both pitot tube and static port can be obtained from a hardware store or even a pet shop
Good quality tubing is often used for fish tanks and it has just the right diameter
Please note that this kind of tubing is not advised for pressurized aircraft In this case you would need to obtain aircraft
grade tubing of suitable diameter You would also have to use hose clamps to fasten the hose onto the ASI-4 pitot and
static ports The ASI-4 allows you to calibrate the airspeed reading This is done under the “AIRSPEED SETUP” menu
item The main reason for this is to be able to remove errors introduced due to the airflow around your aircraft which may
have an effect on your pitot tube pressure
11.1 General Connection Diagram
The use of an external 1A fuse is recommended Connect the supply terminals to your aircrafts power supply The ASI-4
can be used on both 12V and 24V without the use of any pre-regulators Ensure that the supply voltage will not drop
below 8V during operation as this may result in incorrect readings

Vega SI-4 Operating Manual Page 12
11.2 Pressure Port Dimensions
11.3 SI-4 Cable connections
Main connector (D15 connector: Unit Female, Cable Male)
12 Warranty
This product carries a warranty for a period of one year from date of purchase against faulty workmanship or defective
materials, provided there is no evidence that the unit has been mishandled or misused Warranty is limited to the
replacement of faulty components and includes the cost of labor Shipping costs are for the account of the purchaser
Damage as a result of applying excessive pressure to the pressure ports are excluded from warranty.
D15 Pin Color Function
1 Red 8-30Vdc power via power switch / circuit
breaker and fuse.
2 Black Ground.
3 - RS232 Transmit data (Firmware upgrading)
4 - RS232 Receive data (Firmware upgrading)
15 White larm Output (Open collector)
Note: Product warranty excludes damages caused by unprotected, unsuitable or incorrectly wired
electrical supplies and or sensors, and damage caused by inductive loads
Inches Millimeters
Min Max Min Max
0.248 0.278 6.30 7.06
B0.420 0.440 10.67 11.18
C0.182 0.194 4.62 4.93
D0.310 0.330 7.87 8.38

Vega SI-4 Operating Manual Page 13
13 Disclaimer
Operation of this instrument is the sole responsibility of the purchaser of the unit The user must make themselves familiar
with the operation of this instrument and the effect of any possible failure or malfunction
This instrument is not certified by the FAA Fitting of this instrument to certified aircraft is subject to the rules and
conditions pertaining to such in your country Please check with your local aviation authorities if in doubt This instrument
is intended for ultralight, microlight, homebuilt and experimental aircraft Operation of this instrument is the sole
responsibility of the pilot in command (PIC) of the aircraft This person must be proficient and carry a valid and relevant
pilot’s license This person has to make themselves familiar with the operation of this instrument and the effect of any
possible failure or malfunction Under no circumstances does the manufacturer condone usage of this instrument for IFR
flights
IMPORT NT NOTICE:
You must make your own determination if the products sold by MGL Avionics are safe and effective for your intended
applications MGL Avionics makes no representations or warranties as to either the suitability of any of the products we
sell as to your particular application or the compatibility of any of the products we sell with other products you may buy
from us or anywhere else, and we disclaim any warranties or representations that may otherwise arise by law Also, we
offer no specific advice on how to install any of the products we sell other than passing along anything that may have
been provided to us by the manufacturer or other issues If you are in need of further information or guidance, please turn
to the manufacturer, FAA Advisory Circulars and guidance materials, the Experimental Aircraft Association, or other
reputable sources
Other instruments in the Stratomaster Vega series
HRS-1 Artificial Horizon and Magnetic Compass Indicator
LT-5 Altimeter and Vertical Speed Indicator (VSI)
SI-4 Airspeed Indicator (ASI)
SV-1 Altimeter, Airspeed (ASI) and Vertical Speed Indicator (VSI)
EMS-1 Engine Monitoring System
FF-4 Fuel Computer
INFO-1 Information Display (G-force meter, RTC, Outside Air Temperature (OAT), Volts and
Current display)
M G-1 Magnetic Compass Indicator
M P-3 Manifold Pressure and RPM Indicator
RPM-1 Universal Engine / Rotor RPM Indicator
TC-4 4-Channel Thermocouple (EGT/CHT) Indicator
TP-3 Universal Temperature and Pressure Indicator
The manufacturer reserves the right to alter any specification without notice