Alpha Systems AOA derives information from a custom designed AOA probe that is calibrated to the aircraft, in-flight, at a specific Angle of Attack known as "Optimum Alpha Angle". The system, once calibrated, allows the display to give AOA readouts for the pilot to use as additional information during slow flight landings and takeoffs. Airspeed is the result of your angle of attack. Angle of attack is defined as the angle of the wing (cord) to the relative wind (direction of flight).

Every aircraft has a different coefficient of lift based on the design of the aircraft and the design of the wing. The cord of the wing is defined as a line from the center of the leading edge through the center of the trailing edge. The Alpha Systems AOA probe mounting plate is designed to "cut to fit" a majority of existing inspection openings. Once cut to fit and mounting holes drilled to match the existing opening, our mounting plate becomes the inspection cover.

Who is the manufacturer of these devices and what is their background?

The company that manufactures the Alpha Systems AOA is called DepotStar, Inc. which is located in Ramsey, MN a northern suburb of Minneapolis. The owner and president is Mark Korin. He started DepotStar in 1996, which is a very diverse design, engineering company that deals with product development, contract manufacturing, automated test equipment design and build, repair of banking equipment and laser printer scanners to name a few. Prior to owning his own company he was an engineer in the medical products field, Manager of Research and Development at a computer and printer company. He has flown Ultra Lights, currently has a VFR pilot license and working on an IFR rating. Mark is rebuilding three AERO, L29 Delfin Ex-Military Jets and has a long time love of flying and aviation.

His motto when designing this product: "There is nothing more rewarding than designing a product that helps saves someone’s life."

How long has this device been on the market?

DepotStar, Inc. designed the first electronic 4" Round panel mount LED gauge in 1997. With the concept of LED's giving a better display and could be seen in the pilots peripheral vision, customers desired a bar graph version that could be mounted high in the panel with mounting options of both vertically and horizontally in the cockpit. Alpha Systems AOA also manufactures 3 versions of a custom differential pressure gauge that does not require any electricity, designed with a high visibility scale, glass aircraft lens, aluminum housings. The Alpha Systems AOA mechanical systems come in 2 1/4", 3 1/8" standard aircraft panel openings and a custom carbon fiber cased, dash mount version that can be recessed into the top of the glare shield for a custom fit.

I have an old LRI, can I get it updated to the new Alpha Systems AOA?

Due to significant improvements of mechnical, electrical, calibration and documentation upgrades, DepotStar has and will continue to support ALL customers of the old LRI and Alpha Systems AOA with technical and customer service by constantly looking at electrical, mechanical and software upgrades along with releasing new products that will help customers in General Aviation utilize Angle of Attack for safer flight. Ask about the trade in program!!

What are the similarities and differences of the Mechanical and Electronic Kits?

Both kits (mechanical and electronic) use the same hoses, mounting plate and AOA probe. Both kits work the same giving the pilot AOA information relating to the amount of lift available from Cruise up to Stall. The digital bar graph (electronic displays) 4" and the new Ultra 2.5" have a bar graph that can be seen from your peripheral vision when mounted at or towards the top of the instrument panel. The mechanical kit (custom differential pressure gauge) has a moving needle. Both systems display AOA indications of available lift once calibrated, in-flight, for the specific aircraft.

Where should I place the Probe and Mounting Plate?

On a certified airplane, most wings have an inspection cover located in a clean airflow area under the wing that would not be blocked by a pitot probe, antenna or strut. Remove the inspection cover, use it as a pattern. Scribe the pattern onto the mounting plate. Then put the mounting plate with the attached probe into the inspection cover spot. The probe should be at least 2 feet outside of the prop area, typically 6 inches minimum from the leading edge and 6 inches up from the trailing edge, in clean air flow. The AOA sense probe will work attached solidly to the aircraft at most locations as long as the air flow at the tip of the probe is in "undisturbed air" at all attitudes, and in slips and skids and not blocked by any other device. The probe is called the AOA sense probe; it has two holes at the lower portion, one in front of the probe and the other on the bottom. When the wing changes angle of attack, our probe senses the differential change while sensing those changes in ram air and gives you a digital readout on the bar graph display or on the mechanical gauge with a needle that moves to indicate the calibrated AOA for your aircraft.

Is the probe measuring airspeed?

It's using the information of ram air and combinations of differential pressure changes calibrated in-flight to develop the set point for your airplane over AOA change of the wing from stall to cruise.

Why is there pressure differential from the two ports?

The design of the AOA probe and the location of the two sense ports changes its information instantaneously based on what the wing sees..., the probe sees. It must be mounted in clean air flow (undisturbed air).

Could the probe mounting plate be mounted on the nose?

It can, as long as there is clean air (pusher aircraft). The pressure differential area is in clean air flow and calibrated to that airplane. Some customers have mounted the probe from their strut, canard and wing tip. The key to having repeatable AOA information is to have the probe in "undisturbed air".

Where are the hoses located?

There are two 1/4" hoses that run from the wing to the cockpit. The hoses need to be restrained following the FAR regulations and outlined in a detailed procedure in our instruction manual.

What are the two functionally different display types?

Alpha Systems manufactures two distinctive versions.
The first is a custom differential pressure gauge, manufactured and calibrated specifically to take the AOA information from our probe and give a reliable, instantaneous needle movement that directly corresponds to the aircrafts AOA. We manufacture three custom, differential pressure gauges. All three displays utilize a needle movement over a calibrated, high visibility, multi colored scale, showing the complete range of the aircrafts AOA from Cruise to Stall once calibrated.
The second is a digital custom LED electronic version taking the AOA information from the probe to an air data computer sending a signal to a digital display configured so that when more LED's are ON, indicates more and more lift for that aircraft regardless of airspeed, gross weight, density altitude changes.

Are there different types of Mechanical Gauges?

We sell three versions, two that mount directly into the standard instrument panel, 2 1/4" and 3 1/8" glass faced custom gauges. We also have a custom carbon fiber cased, dash mount display which attaches onto the glare shield. All three kits come with the same hoses, probe and mounting plate and all hardware to mount into any aircraft.

Are there different types of Electronic Displays?

Alpha Systems AOA currently manufactures 6 versions of electronic digital LED displays. 4” long X 1” wide vertical, 4” long X 1” wide horizontal, 2 ¼ round LED, 2 ½ long X ¾ wide “ULTRA” vertical and horizontal LED versions and the Newest display; the “LEGACY” chevron LED driven display. All electronic kits come complete with an analog control module (Air Data Computer), manual, hoses, probe, probe mounting plate and all hardware. The LED displays face plate has a taupe back ground color.

When is a Form 337 needed?

Our instrument is NOT STC'd or PMA'd currently. We believe based on years of research and talking with numerous FISDO's that our instrument falls under the category of a MINOR alteration. It is up to the mechanic to determine the impact and the level of work to be performed. It is best to contact the mechanic and work through the appropriate FAA requirements specific to your aircraft's installation and the mechanics comfort level for the work to be preforemed. If you were going to add an inspection location with a doublers on a certified aircraft, a form 337 and a field approval is needed. Our unit was designed to replace the existing inspection cover, making it a minor alteration.

Which inspection cover location should be used?

Do to the fact that there are many aircraft types, wing designs, inspection locations, and other variables, a few simple steps should be followed;

1.) CLEAN AIR FLOW, 2.) 2 foot outside the propeller ark minimum, 3.) 6” back from the leading edge, 4.) 6” up from the trailing edge, 5.) if possible, opposite wing than the pito probe (in case of a bird, bug strike) 6.) in front of any aircraft structural part (gear door, strut, antenna) so that at any angle NOTHING blocks the AOA probe from direct undisturbed air.

What do the FISDO's think?

In the opinion of many, they feel this is a minor alteration. We have taken the time to have our IA, A&P write our manual to aid the mechanic. IA's understand the definitions of major and minor alterations. Some FISDO's have sent back the form 337 and have said it is a minor alteration due to sub section 43 which allows for devices like these that won't effect operation or hook into systems that could be affected. It is up to the mechanic to decide if it is a minor alteration. We can not legally design or make an instrument to be specifically targeted for certified airplanes, however; the FAA allows for installation of this type of device with the approval of the mechanic or proper paper work (337 and field approval).

What is needed if it is a minor alteration?

The mechanic must install the instrument as outlined in the manual and make a log book entry. Our new installation manuals are so detailed that most mechanics install it under the minor installation procedure.

What is the weight of the kits?

The whole kit is less than 2 lbs (1.8 lbs).

What is the current and voltage range?

The electronic kit at full brightness draws 180mAmps (less that 1/4 amp). The unit will work on 10 volts to 28 volts DC.

What are the dimensions of the horizontal and vertical bar graph?

4 3/8" x 1" x 1" are the dimensions for the 4" displays. The 2 1/2" Ultra display dimensions are 2.5" x .75" x .98". Detailed installation prints are included with the system.

How is the device calibrated?

Calibration is a 3 step process. 1.) Initial ground calibration and two set points in flight. 2.) OAA (Optimum Alpha Angle). 3.) Cruise is required to be completed. Alpha Systems AOA displays angle of attack calibrated to each aircraft. Every airplane stalls at a different angle of attack due to the design of wing for each aircraft. You preset the probe to 50 degrees to the mounting plate (typically the mounting plate is parallel to the cord of the wing). We call that our pre-adjustment angle, which covers most ranges of wings, then you follow an in-flight calibration procedure. Calibration is a combination of both the relationship between the angle of your probe and he angle of attack of your wing. Every wing is different, coefficient of lift and the cord of every airplane is different. The angle of attack of your wing is defined as the center of the leading edge to the center of the trailing edge of that wing (cord) to the relative wind (direction of flight).

What are the steps involved in the In-Flight Calibration?

1.) In-air aircraft flight dynamic. Setting Optimum Alpha Angle (OAA), at a safe altitude for slow flight, reduce power (approximately pattern RPM or manifold setting). Put your airplane at minimum controllable airspeed able to hold altitude with FULL aileron and rudder authority. An example: you are at 5000 ft. practicing holding altitude, pull the stick/yoke back slowly while holding altitude no longer able to climb, NOT DESCENDING, still able to maintain complete aileron and rudder control. You need to identify the one particular flight criteria for your airplane of Optimum Alpha Angle (OAA). Identify the slowest you can fly comfortably, able to hold altitude (NOT DESCENDING) along with complete control of your airplane.

Mechanical System: If you have the mechanical unit, the needle must be at the red/yellow junction when the aircraft is flown and held at OAA (Optimum Alpha Angle). If the needle is not at the red and yellow junction, land your airplane, reposition the probe forward or aft depending on where the needle was high or low in the calibration flight. Then take the airplane back up in the air and verify that by repositioning, the probe is pushing the needle back down to that one known condition. You must identify the aircraft's ability to hold altitude, ZERO SINK, while keeping complete control of your airplane with full aileron and rudder authority.

Electronic System: If you have an electronic unit, it is a matter of pushing a button during the in-flight calibration procedure. The electronic unit adjusts itself. Please note: if the pre-set probe angle is outside of the pressure differential range, when in the calibration mode, the electronic/software system will give an LED indication to the pilot which direction to move the AOA probe to allow for a full scale display custom calibrated to the AOA unique for your aircraft. The electronic system calibrates at the aircrafts "CRUISE" flight dynamic to set the top end of the LED scale, (when the last green LED is illuminated and all other LED's are off).

What is the difference with the Alpha Systems AOA Calibration verses the competition or with the glass AOA?

We've identified that during ALL Military operations, ALL Carrier landings and on every commercial aircraft, AOA is used to increase safety for the pilot and their crews, for stabilized approaches and proper climb outs. Pilots need to know instantaneously, accurately, how much lift is or is not available. Military pilots have an identifier to where the aircraft can hold altitude, ZERO SINK with FULL aileron, elevator and rudder authority. We calibrate at that set point, Optimum Alpha Angle (OAA). Our displays utilize ultra bright LED's. The electronic display systems were designed to be mounted in the pilots' peripheral vision, the displays are intuitive in that the more LED's that are on, the more lift that aircraft has, reagardless of airspeed. Also, standard color coordinations GREEN = lots of lift, YELLOW = caution, diminishing lift, BLUE = OAA Optimum Alpha Angle, ONLY RED = danger, loss of control, descending or even approaching or entering a stall.
Stabilized approaches require knowing exactly how much lift the wing is generating at any flight situation. Air speed is not enough, Alpha Systems AOA takes the approach if we know exactly where OAA (Optimum Alpha Angle) is, we calibrate to the specific performance of the aircrafts wing, then we can identify Stall, Vx, Vy, Max Climb Angle, Cruise or any flight dynamic specific to the aircraft.
We believe that our system is superior based on the simplicity of the design, NO moving parts, light weight, (less than 2 lbs), extremely and instantaneously responsive, accurate, low current draw (180mv at full brightness), and versions with no electricity needed available. Easy to install, no modifications to the aircraft, AOA probe and mounting plate replaces inspection cover. Considered a Minor alteration by many mechanics and FISDO's.

Completely standalone, NO connections to existing Pitot, or Static aircraft systems. Having an independent AOA display separate from the "glass panels" makes it a much more intuitive flight system. AOA is everything.

And the best is last, we believe from our large customer base and feedback, that an Alpha Systems AOA system will aid the pilot, increasing critical identification of available lift allowing for a safer flight. With this in mind, Alpha Systems warranties the instrument for life and we stand behind our product with a 100% satisfaction guarantee!! Yes that's right, I want every customer and their friends and families the benefit to have an instrument that could help save their life and past customer comments testify the safety benefits!

What is the retail price?

See Store for Pricing

How long does it take a mechanic to install an Alpha Systems Angle of Attack kit?

It typically takes 6 to 8 hours depending on the type of aircraft, display location, probe mount, hose routing and paperwork.

I know I want to buy one - I just don't know which one to choose - how can I decide?

-Either system works consistently, will give the same indications repeatable.

-Either system measures in real time, instantaneous.

-Electronic: Is identifiable in your peripheral vision, no need to focus on it. The LED display should be located at or near the top of the instrument panel, close to the glare shield. Some customers prefer mounting on the top of the glare shield. Push of a button calibration. At cruise flight you will see the last green LED illuminated, as you reduce power/pull stick back, All the LED's indicating a range of available AOA or reduced changes of available lift. The LED's indicate a slow flight range of available lift, more lift available the more LED's are lit. Lights go out less and less lift that is available. Audio indicator gives 3 beeps when coming within 2 LED's of OAA. 16 different LED brightness levels. Automatic photo cell, will automatically switch from day time brightness pre-set to night time brightness pre-set.

-Mechanical: 3 different mounting options available. 2 1/4, 3 1/8 or dash-mount gauge kits available. Does not use or connect to any system and does not need electricity. For those who like the "needle" type instrument indications. Prepeatable, reliable, simple.

Which kit has been purchased more?

The 4" Horizontal electronic kits. This display can be seen in your peripheral vision and be mounted up towards the top of the instrument panel. Easy push button calibration steps, beeper to identify reduced AOA, 16 brightness steps, can be seen in day light and dimmed for night time flight.

What happens if I purchase the horizontal and then decide I need the vertical instead?

We will gladly exchange the display for you. The size of the horizontal and vertical is the same; the only difference is the overlay graphics.

What is the screw size?

6-32 threaded, for mounting top, back or bottom. Optional rectangle mounting bracket to flush mount it into the panel are included with either the Vertical or Horizontal 4" LED displays and both the Vertical and Horizontal Ultra 2 1/2" AOA displays.

How bright are the lights on the electronic displays?

There are 16 independent LED brightness steps. The LED display utilizes ultra bright LED's that are diffused and can be seen in bright sun and can be turned down for a night time brightness level. There is also an automatic photo cell to switch from night time preset and a daytime preset.

Where would you install a gauge on a Maule airplane?

Actually, it’s customer dependent, most sales are of the electronic LED bar graph type, but ultimately it’s up to you! We tell all AOA customers “Get it up as high in the cockpit or panel as possible”. The whole idea is that the LED bar graph can be seen and interpreted WITHOUT taking you focus off of the landing, other planes in the pattern, approach or runway.

Are your units PMA'd or STC'd?

The Alpha Systems AOA instruments are NOT STC'd or PMA'd. We beleive that the Alpha Systems AOA is a minor alteration, ultimately that decision is up to your mechanic to make the determination. (Major vs. Minor)

Do you follow FAR regulations?

Yes, they are detailed in our installation manuals. We also include a FAA reference library of the appropriate FAR's on CD for our customer's references with the kits.

How would flaps affect our gauge system and the calibration procedure?

We calibrate "clean" and identify the LED or needle offset at the same in-flight dynamic with flaps in the landing configuration. By adding flaps will change the cord of the wing and/or the coefficient of lift. There is a reduced amount of LED's that will indicate the Optimum Alpha Angle (OAA) or the ability for the aircraft to hold altitude, ZERO SINK in slow flight with complete aileron, elevator and rudder authority.

Which magazines or newspapers have written articles about your device?

AOA is an interesting topic. Ever since the Wright Brothers correlated AOA back in 1906, AOA has been written about. Manufactures have focused on the Military and Commercial industries. Every Military and Commercial aircraft flying today has an AOA system as a PRIMARY flight system. Many articles have been written about our method of identifying AOA since the early 1970’s. Articles in magazines such as “Pilot Getaway”, “Aviation Consumer Report”, and our products have been showcased in the Minnesota local newspapers and cable TV spotlights.

What results will you get if you fly your airplane at a 45 degree bank?

It will be the same repeatable LED result. Pull aircraft into a minimum controllable, roll into 45 degree bank, should get the same LED OAA display.