UAV Propulsion Tech Post #28 – Orbital Heavy Fuel UAV Engine White Paper

Heavy Fuel UAV EngineWhite Paper-twitter

I am the US rep for Orbital and market their propulsion systems to US UAV customers.  I have permission from Orbital to re-print a presentation they made at Technion – Israel’s Institute of Technology’s Sixth Conference on Propulsion Technologies for Unmanned Aerial Vehicles in Haifa, Israel on January 26th, 2017 titled Orbital FlexDI: Providing reliable and efficient heavy-fuel IC engines for the UAV industry authored by Dr. Geoff Cathcart and John Tubb from Orbital.

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UAV Propulsion Tech Post #27 – COTS UAV Servos

Blog post #27

I am the US representative for Volz Servos GmbH & Co. Kg located in Offenbach, Germany.  They produce high end actuators for industrial and aerospace applications.  They have been in business over 30 years and have several COTS solutions and can also develop custom solutions.  Volz servos are flying on several global UAV platforms around the world including the following (in the public domain): Lockheed Martin Fury 1500, Northrop Grumman BAT, AAI Corp Aerosonde Mk4.7, Aeronautics Orbiter, EADS Cassidian DO-DT target drones, Orbital Scan Eagle engine for Insitu, and Schiebel Camcopter S-100. Volz have high end optional features such as brushless motors, contactless postion sensor, position feedback, redundant solutions and clutch mechanisms for OPV (optionally piloted vehicle) applications.  All hardware has traceability which can be difficult to obtain from high volume hobby RC servos.  Volz is also ISO9001:2008 certified and applies advanced quality systems for demanding UAV requirements.  This can include 100% HASS (highly accelerated stress screening) or even custom measurements depending on customer needs.

Volz blog

Key features of Volz servos are:

  • CNC machined aluminum actuator case.
  • IP67 standard for water/dust intrusion protection.
  • Multi purpose lug mounts for variable servo fixation.
  • Integrated microprocessor controlled PC boards.
  • Fully programmable by the customer.

Optional features:

  • ISS System protects gear train against shock loads.
  • Serial communication interface (DA26/DA30 and larger).
  • Wear free position sensor for improved reliability/life.
  • Brushless motor for improved reliability/life.

Volz does produce small servos (DA10 & DA13) but I am focusing on the main servos that are typically used for UAV applications in this blog post.  I have noted the COTS DA14-DA30 options below (including throttle, submersible, and OPV-optionally piloted vehicle alternatives).









DA14 (14mm class) – Link to datasheet/CAD


DA15 (15mm class) – Link to datasheet/CAD









DA20 (20mm class) – Link to datasheet/CAD

DA22 blog

DA22 (22mm class) – Link to datasheet/CAD

DA26 blog








DA26 (26mm class) – Link to datasheet/CAD

DA30 blog








DA30 (30mm class) – Link to datasheet/CAD

Redundant blog








Duplex – Redundant Class – Link to datasheet/CAD

OPV blog








OPV (optionally piloted vehicle) Class – Includes electro-mechanical clutch – Link to datasheet/CAD

throttle blog

Throttle servo class – Link to datasheet/CAD

Due to the high reliability of these servos, they have been selected by some of the largest UAV producers in the world.  I have noted the references below that are in the public domain.


You can find out more info about these servo actuator solutions by visiting my Volz page at www.uavpropulsiontech.com/volz or the Volz website at www.volz-servos.com.  If you have any questions regarding these solutions, please call or email me at: bob@uavpropulsiontech.com.  PH: +1 (810) 441-1457

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UAV Propulsion Tech Post #26 – My Interview w/POMS & Associates about How Drones Are Being Used Today



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UAV Propulsion Tech Post #25 – Highlights from the Commercial UAV Expo 2016


I attended the Commercial UAV Expo that was held at the MGM Grand Convention Center in Las Vegas, Nevada.  I arrived on OCT 31st and supported the MicroPilot booth during the Halloween reception and also supported on NOV 1st.  I also got a chance to check out the show and thought it would be good to show some of the things I saw.  The first thing I noticed that was different from the Interdrone show I attended a month previously is there were fewer hobby companies exhibiting which is to be expected since it had a “commercial” focus.  Check out their website for more info: http://www.expouav.com/










Here is a shot of me at the MicroPilot booth.  I supported Kyle Hayes who is an engineer from MicroPilot.  We had lots of interest in our board mount, enclosed and triple redundant autopilots as the commercial guys were looking for a more reliable solution than the hobby hardware that they are currently flying.  Particularly those that have expensive air vehicles and payloads like  LiDAR.  Check out my MicroPilot page for more info: http://www.uavpropulsiontech.com/micropilot.

The one thing I noticed while walking the show is there were lots of helicopters on display.  Solutions from Pulse Aero, Leptron, Altus Intelligence, and Swiss Drones.



Pulse Aerospace had their Vapor 55 on display with a LiDAR package.  You can find out more about their solutions by visiting: http://www.pulseaero.com/.



Altus Intelligence out of New Zealand had their ORC4 helicopter on display.  You can find out more about Altus Intelligence by visiting their website at: https://altusintelligence.com/.


Swiss Drones had their SDO 50V2 helicopter on display.  This was a very impressive helicopter using a gas turbine engine (for reduced vibration for enhanced sensor performance), and capable of a 50kg payload.  They can carry a multispectral camera or crop spraying system.  You can find out more by visiting: http://www.swissdrones.com/




I neglected to get a picture at the show of the Leptron Avenger helicopter so had to grab one from their website.  They have two variants (electric and gasoline engine) providing 20 min or 2hr endurance respectively.  Payloads of EO/IR and LiDAR as well as HD video.   Check out their website for more info: http://www.leptron.com/





Another interesting find was the “Wingcopter” hybrid UAV out of Germany.  This was on display at the MultiRotor booth  and has rotating propellers to transition from VTOL to horizontal flight.  You can find more about this solution by visiting http://www.wingcopter.com/ or http://www.multirotor.net.








Payloads also had a good presence especially LiDAR and infrared.  Velodyne are LiDAR experts and have released three new LiDAR’s this year.  These include: Puck Hi-Res™ sensor,  VLP-16 Puck™ and the Puck LITE™.  You can find out more about Velodyne by visiting: http://velodynelidar.com/index.html











I have read about the flying bird solution from Clear Flight Solutions but this was the first time to see it first hand.  This is a great product with flapping wings that provides a unique ISR solution that is less noticeable than a multicopter or fixed wing with electric or piston engines.  I would think this would provide some stealth capability that could be beneficial.  From what I understand they don’t sell the system but are building a global service business using these birds.  You can find out more by visiting: http://clearflightsolutions.com/.

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UAV Propulsion Tech Post #24 – Info Graphic: The Rise of the Drone Industry

The info graphic is courtesy of The Drone Worx company out of the UK and is published on this blog with their permission. They are a hobby/commercial drone retailer. You can find out more info by visiting http://www.thedroneworx.co.uk

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UAV Propulsion Tech Post #23 – Slideshare: Top 10 Blogs from UAV Propulsion Tech

I have been posting blogs on UAV Propulsion Tech for about a year and a half so I wanted to check my Google Analytics for blog post activity from JAN-OCT 2016. I summarized the results in the Slideshare below:

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UAV Propulsion Tech Post #22 – Highlights from InterDrone 2016


I attended the  InterDrone conference that was held at the Paris Hotel in Las Vegas SEP 7-9.   I attended last year  and supported the  MicroPilot exhibit.  MicroPilot exhibited again this year and I spent some time supporting their booth and also spent some time checking out some of the new products on display.  I thought I would highlight some of what I saw in this blog post.











MicroPilot was displaying three variants of their autopilots (board mount, enclosed, and triple redundant).  We had lots of interest from drone users and manufacturers that were not happy with their low cost open source solutions.  Check out my MicroPilot page for more info on their autopilot solutions. http://www.uavpropulsiontech.com/micropilot









I stopped by the  Insitu booth to get a demo of their new INEXATM intuitive ground control system plug-in for Arducopter.  The VR demo was pretty impressive and their pricing for the consumer/commercial market is only $60/year for this highly functional ground control station plug-in.  You can find out more here: https://insitu-web-store.myshopify.com/products/inexa







Saxon Remote Systems (formerly Skynet) had a large 20’x20′ booth that included their Viper M10 electric UAV and a ground  control station vehicle solution.  Unfortunately I didn’t get a picture of their booth but they were very busy during the show and one of the few commercial/military high end solution providers at this event.  Their Viper M10 can fly for over 3 hrs and Saxon has a family of these UAV’s from 4′ wingspan to 20′ wingspan.  The larger ones utilize piston engines and have longer endurance than the electrics.  Check out their website for more info: http://saxonremotesystems.com/









xCraft had their new PhoneDrone Ethos on display which is supposed to be available for sale sometime this fall.  These are they guys that pitched their xPlusOne drone to Shark Tank.  The xPlusOne takes off vertical and has an x-wing configuration that allows it to fly vertical.  They also had their new xCraft 2 on display (their next generation with new autopilot).  Check out their website for more info: http://xcraft.io/










I stopped by the Autel booth to check out their x-Star consumer drone.  This looks very similar to the DJI Phantom.  They have a nice kit that includes 4k camera, gimbal, RC controller and hard case for $899.  I am tempted.  You can find out more about Autel by visiting their website:  https://www.autelrobotics.com/.  Or check out the Amazon Link to purchase.










ProDrone out of Japan had a very interesting drone on display that had robotic arms.  This very large drone (44lbs) can utilize its robotic arms to grab a 22lb object.  You can find out more by visiting ProDrone’s website:  https://www.prodrone.jp/en/.  There is also a YouTube Video showing this  drone in operation.







Another high end UAV provider (DroneTech UAV) had their AV-1 Albatross on display.  This is a fixed wing with 4-rotors to take-off and land vertically.  ITAR free aircraft with 8hr endurance.  They also have an AV-2 Albatross with 28hr endurance which uses twin Hirth 4102 8hp engines.  You can find out more by visiting: http://www.dronetechuav.com/










HoneyComb Corp had their Ag Drone System on display.  This Ag drone is very durable compared to other similar Ag drones because it has a Kevlar exoskeleton.  The system includes dual cameras (RBG, NIR) and is fully autonomous.  Check out their website for more info: http://www.honeycombcorp.com/

There were other products on display of course but I thought I would highlight the ones that caught my eye.  I will be attending the Commercial UAV Expo in Las Vegas OCT 31 and NOV 1.  I will try to post another  blog on that show.

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UAV Propulsion Tech Post #21 – UAV System Solutions

UAV System Solutions Blog Post 21

UPDATED AUG 9, 2017: UAV’s require several systems to keep them in the air and allow them to complete their mission.  I have been working in the UAV business over 10 years mainly supporting propulsion systems but in the last 5 years I have expanded my business to include other systems.  My focus for UAV Propulsion Tech, is to find the best UAV solution providers outside of the US and offer their solutions into the US and global UAV market.  I thought I would summarize these solutions in this months blog.

The graphic below shows the systems that will be detailed further below.











A: Propulsion- This is what keeps the UAV  in the air but also provides electrical power to the air vehicle and payload via a generator.  It also can include an engine mount which is critical to minimize vibration transmission to the payload which can cause camera issues.  It also typically has an engine management system that interfaces with the flight computer to monitor engine health (like cylinder head temp, exhaust gas temp, throttle position, manifold air pressure, and can also calculate fuel consumption).  The propeller is tested with the engine (and sometimes supplied) but is usually specified by the UAV manufacturer’s aerospace engineers.  The propeller can be direct driven from the engine or utilize a propeller speed reduction system (either belt or gear) to allow the UAV to utilize a larger propeller spinning at a lower speed.  This decreases noise and increases thrust.

UAV Propulsion Tech provides propulsion solutions from Orbital (Australia), Neva Aerospace (United Kingdom) and Hirth (Germany).  Orbital’s expertise is in custom direct injected 2-stroke engines that enable operation on heavy fuel’s such as Jet A, JP5, JP8.  The DI system provides significant fuel consumption reduction benefits at cruise because the engine can run leaner than a typical port injected or carbureted engine.   They can also apply their direct injection system to existing piston or rotary engines to improve the combustion process and enable operation on heavy fuel. Examples of their UAV customers (in the public domain) include the Aerosonde MK4.7 engine (now produced by Lycoming) and the new ScanEagle N20 engine (recently detailed in Unmanned Systems Magazine – #8).

Orbital UAVe








You can find out more details by visiting my Orbital page at http://www.uavpropulsiontech.com/orbital or http://uave.orbitalcorp.com.au/

Neva Aerospace’s expertise is in electric turbofans (ETFs) optimized for static thrust for VTOL/STOL.  The unique turbofan housing design further ingeniously boosts thrust with no extra weight added.  The breakthrough technology of the Athena Series ETFs will displace uncaged rotor blades in the current commercial drone applications and will create exciting new possibilities for the development of the next generation of unmanned aerial systems.  Neva Aerospace is a European consortium based in the United Kingdom. It partners with key clients, technology suppliers, and financial institutions to develop technologies for unmanned air vehicles (UAVs), Unmanned Air Cargo(UAC), aerial robotic platforms (ARP), and electric aviation. It owns a portfolio of patents and technologies which are among the most advanced worldwide. As of January 2016 Neva Consortium counts 5 companies with more than 100 people.

Neva slider








You can find out more by visiting my Neva Aerospace page at http://uavpropulsiontech.com/neva-aerospace-electric-turbofans/ or www.neva-aero.com.

Hirth’s expertise is in COTS and custom 2-stroke aircraft engines and they currently produce engines from 8hp to 100hp.  They have been in business for almost 100 years and have produced over 1 million engines.  Their 2-strokes are used in ultralights, powered parachutes, gyrocopters, gliders, hovercraft, generators, water pumps, go-karts and UAV’s.  Their technologies include advanced engine management systems for both gasoline and heavy fuel, integrated starter/generators and relationships with some of the most reputable 2-stroke components suppliers in the world.  Their UAV customers (in the public domain) include: Saab Skeldar, Indra Pelicano, EMT Luna, Dronetech AV-1 Albatross, Northrop Bat, Denel Seeker 200, Ruag Ranger, and IDS Hero-150.

Hirth Slider 2016









You can find out more by visiting  my Hirth page at http://www.uavpropulsiontech.com/hirth or http://www.hirth-engines.de

B: Gimbals- The primary UAV payload is typically a gyro-stabilized electro-optical (EO) and infrared (IR) camera gimbal.  The payload can also have a laser range finder or pointer.  These gimbal systems also have optional video tracking, geo-location and geo-positioning.  UAV Propulsion Tech provides gimbal solutions from DST Control (Sweden).  These systems are flying on several UAV’s today and their OTUS-U135 is one of the smallest gimbals on the market with the best value for the advanced capabilities it provides.  The OTUS-U250 is a 10″ gimbal and is the largest in the DST Control family and is very cost competitive compared to other solutions of similar size.











You can find out more by visiting my DST Control page at www.uavpropulsiontech.co/dst-control or www.dst.se.

C: Fuel Modules-Another critical system in a UAV is the fuel delivery module.  This would typically include a fuel tank, fuel pump, and fuel level sensor.  The operation  of the UAV can impact delivery of fuel to the engine which can cause fuel starvation and engine stall.  Critical events can include launch, altitude pressure changes, and flight maneuvers (pitch/yaw).  The fuel delivery module also has to provide a means to minimize slosh effects and provide filtered fuel to the engine.  UAV Propulsion Tech provides fuel module solutions from Orbital.  The picture below shows the new ScanEagle N20 propulsion system which includes the engine as well as the fuel delivery module.  Orbital can develop custom turnkey fuel delivery systems for a specific UAV application.









Hirth does  not provide fuel delivery modules but does provide in-line fuel pumps and fuel pressure regulators for all UAV engines.  Shown below is a fuel delivery module concept from UAV Propulsion Tech that shows a COTS configuration that can be customized for specific applications.  This is shown just to illustrate a typical tank system and  is not available for sale.  Fuel delivery modules can however be provided by Orbital.











A key component of the fuel delivery module is the fuel level sensor.  I started representing Reventec, Ltd. out of the United Kingdom in July 2017 and offer their capacitive liquid level sensors, fuel flow sensors as well as engine sensors (throttle, temperature, speed).   The company was established in 2013 by Neville Meech, an experienced and internationally recognized design engineer. Having previously led the Motorsport design activities for a UK sensor company, Meech brings a vast amount of experience working with some of the most recognized race teams and sports car manufacturers in the world, predominantly within Formula 1®, ELMS/IMSA, WEC and IndyCar.  Reventec now has a rapidly growing design team, combining a huge range of mechanical and electronic design expertise.  Reventec are primarily involved in the development of products for use in harsh environments, with particular experience in the design of products for military vehicles, unmanned aircraft, race cars, industrial machines, specialist vehicles and equipment.

Reventec newYou can find out more by visiting my Reventec page at: http://uavpropulsiontech.com/reventec-liquid-level-sensors-engine-throttletempspeed-sensors/ or visiting www.reventec.com

D: Autopilots-The autopilot is a critical system of a UAV and is responsible for controlling the flight of the UAV.  It ties into several UAV systems to enable autonomous or remote piloted flight.  The autopilot links to a ground control station (GCS) via a radio modem and the GCS is used to develop waypoints for the flight plan and monitor operation.   UAV Propulsion Tech provides autopilot solutions from MicroPilot (Canada).  MicroPilot has been providing professional autopilots for the UAV market for over 20 years and has systems flying all over the world.  Their autopilot solutions include board mount (weighs only 28g), enclosed (includes redundant long range communication data link) or triple redundant (3 autopilots for ultimate reliability).  These solutions have been developed for fixed wing, multi-copter, and helicopter applications.  MicroPilot’s autopilots are not open source but they do offer XTender which is a software developers kit to enable customization.  This allows the UAV customer a way to differentiate their UAV from their competitors.  MicroPilot’s True Hardware-in-Loop simulator offers UAV integrators and researchers the highest fidelity autopilot simulation available on the market today.

New micropilot slider








You can find out more by visiting my MicroPilot page at www.uavpropulsiontech.com/micropilot or www.micropilot.com.

E: Parachutes – Parachutes can be used in a UAV as a means of recovery (instead of a net or runway) or as a means of rescue in case of a system failure.  Most are used for rescue situations to save the air vehicle and payload assets.  The challenge is always trying to find space for a parachute and deal with the added weight.  UAV Propulsion Tech provides parachute solutions from Skygraphics (Germany).  Their ProtectUAV parachutes provide a lightweight/compact solution over other products on the market.  They are currently being utilized by several UAV companies and ProtectUAV also recently launched a multi-copter solution.  ProtectUAV’s solutions cover fixed wing applications up to 200kg MTOW and multi-copter applications up to 28kg MTOW.

protectUAV marketing picture









You can find out more by visiting my Skygraphics page at www.uavpropulsiontech.com/skygraphics or www.protectuav.com.

F: Servos-Another critical component for UAV’s are servos.  Servos are used to move control surfaces (like rudder, ailerons, flaps, etc.), control the engine throttle and sometimes used to trigger certain options (like a compartment door for a parachute).  UAV Propulsion Tech provides servo solutions from Volz (Germany).  Volz has been designing/producing high end servos since 1983 and are flying on several UAV’s including Aerosonde MK4.7, Northrop Bat, Schiebel Camcopter, Airbus target drones, Lockheed Martin Fury, Aeronautics Orbiter and several others.  They provide a complete range of servos from DA15 (15mm) to DA30 (30mm) and are now offering redundant and OPV (optionally piloted vehicle) variants of their larger DA26 and DA30 servos.


Hirth-Volz web









They also have throttle servos that can be mounted directly to the engine throttle and can withstand the vibration because of their brushless motor and contactless sensor design.



You can find out more by visiting my Volz page at www.uavpropulsiontech.com/volz or www.volz-servos.com.

Launchers:  Another key system that I can provide for small fixed wing UAV’s is a pneumatic launcher from Eli Airborne Systems out of Estonia.   This UAV pneumatic launcher has been developed to accelerate UAV-s and other aircraft with MTOW up to 40 kg and launch them at speeds up to 25m/s. The launcher is light-weight, battery-operated and is quickly assembled. The system is easily portable in two special rugged cases. Custom carriage rods can be designed based on clients UAV specifications.  Eli Airborne Solutions is a leading developer of military solutions.  They also produce a parachute release mechanism that automatically separates the parachute from the UAV when the UAV is on the ground to protect the wind from dragging the air vehicle and causing damage.

Eli UAV solutions


You can find out more by visiting my Eli pages: Launcher – http://uavpropulsiontech.com/Eli Airborne Systems or http://eli.ee/

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UAV Propulsion Tech Post #20 – UAV EO/IR Gimbal Solutions

Blog #20

I just started representing DST Control in April of this year and market their gyro-stabilized EO/IR gimbal solutions and thermal imagers in North America.  DST Control is based in Linköping, Sweden and has several European UAV customers but wants to expand into the US UAV market.  I thought I would put together a blog showing some of the details of DST’s solutions.

Gimbal requirements are putting higher demands on the ability to see and detect under difficult conditions.  These requirements include pointing stability, detection distance, photon sensitivity and bandwidth.   This forces the development of specialized sensors, micro mechanical precision components, advanced software and electronics hardware resulting in more complex gimbal systems.

DST has a  range of advanced gyro-stabilized gimbal systems from  135mm diameter to 254mm diameter as shown below:


Figure 1: DST Control Gyro-Stabilized Gimbal Product Line

DST named their gimbal line “OTUS” which is Latin for owl since the owl’s head operates like a perfect gimbal.  The OTUS-U135 is one of the smallest sensor systems on the market and can package 1 or 2 sensors (such as EO/IR cameras or laser).   They go up in size to package larger sensors and additional sensors.  The OTUS-U205 can package 3 sensors and the OTUS-U250 is the largest with the best stabilization and sensor options.  The OTUS-U135, OTUS-L170 and OTUS-L205 are available with either <100μrad stabilization or <250μrad stabilization.  The OTUS-U250 is a 4-axis gimbal and has the highest stabilization of <50μrad  and has the largest area for sensors.  Reference the photo below of the inside of the OTUS-U250.










Figure 2 – Inside of OTUS-U250

I have detailed the specifications of the OTUS family of gyro-stabilized gimbals further below:

OTUS-U135 (Product Brochure)





OTUS-L170 (Product Brochure)




OTUS-L205 (Product Brochure)




OTUS-U250 (Product Brochure)




The sensor options are Sony EO cameras, FLIR infrared cameras, DST’s own SAITIS-640 thermal imagers, and laser pointers/range finders/illuminators.  A key benefit of SAITIS-640 thermal imagers is they are not ITAR controlled like other infrared solutions.

SAITIS-640 is one of the smallest long-wave infrared imagers available on the market.  SAITIS-640 is based upon a uncooled microbolometer FPA (amorphous silicon, spectral band 8-14 μm) with 640×480 pixels resolution. Unique features for the SAITIS-640 is its low weight and size (from 27mm x 27mm x 26mm) but also the minimum power requirements (1W).

The video output is PAL/NTSC video but also digital video output is available. The camera is controlled via a standard RS-232 interface. The camera is available with or without integrated shutter for NUC (Non-Uniformity Correction). The shutter-less version, SAITIS-640-X, requires an external shutter to perform the NUC. The camera with integrated shutter, SAITIS-640-S, has an automatic NUC manager integrated for easy-to-use operations.

The camera is ready-to-use without any training. All image processing is executed on-board, hence no external units are required. The SAITIS-640 can be equipped with a wide range of optics optimized for short-, medium or long range operations and has maximum exportability even in full frame rate.

I have supplied more details below for DST SAITIS-640 thermal imager alternatives:

SAITIS-640 (Product Brochure)




Gimbal Options:

Video Tracking:  The Automatic Video Tracking Option means that the OTUS gimbal will have a software function capable of locking the LOS onto a specified object in the image.  Hence a moving object on the ground will remain locked onto the center of the OTUS video or IR image at all times, provided the optical features meet certain requirements.

Geo-Location: The Geo-Location option means that the OTUS gimbal will have a software function capable of outputting the GPS position of the viewed object centered in the video or IR image. For this function to work, it is required that two external sensors are connected to the gimbal:

  1. An external GPS sensor providing the position  of the vehicle (e.g. the position of the base of the gimbal).
  2. An external heading source providing the heading of the vehicle (e.g. the heading of the base of the gimbal).

Geo-Tracking: The Geo-Tracking option means that the OTUS gimbal will have a software function capable of locking the LOS onto a GPS geographical position on the ground. Hence the gimbal can be commanded to move to and maintain any given geographical position centered in the image.  This option assumes that the Geo-Location Option is enabled.

Laser Accessories:

  • Laser Range Finder (50 m to 4000 m): a device used to measure the distance to an object by measuring the time of flight for a laser beam emitted by the sensor and reflected by the object.
  • Laser Pointer & Laser Illuminator: a device that sends a laser beam to point out an object. The device is available with a wide variety of specifications depending on customer demands.

Low Temperature Option: means that the OTUS Gimbal unit is equipped with an internal heating element to ensure proper operation of payloads that are otherwise unable to operate at lower temperature. The lowest possible operating temperature is -40°C.


Figure 3 – Firefly Hand Control Unit (HCU)

The Handheld Control Unit (HCU) is used for manual control and monitoring of one OTUS Gimbal Unit at a time.  The HCU is intended for direct wired connection to the OTUS Gimbal Unit, or for connection to the OTUS Gimbal Unit via an external wireless link. The external wireless link must be capable of bilateral transmission of a serial data stream between the HCU and the Gimbal Unit, and unilateral transmission of an analogue video signal from the Gimbal Unit to the HCU.

If you have any questions regarding these solutions, please call or email me at: bob@uavpropulsiontech.com.  PH: +1 (810) 441-1457.

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UAV Propulsion Tech Post #19 – Triple Redundant UAV Autopilot


I am the US rep for MicroPilot and market their autopilots to US UAV customers.  I have permission from MicroPilot to re-print a white paper they have on their website titled “MP21283x MicroPilot’s Triple Redundant UAV Autopilot” authored by Sarah Vallely in 2010.  I think this white paper is more relevant today as the defense and commercial markets are trying to improve UAV reliability when flying in extreme environments in theater as well as in civilian airspace.

MP21283x MicroPilot’s Triple Redundant UAV Autopilot

Triple redundancy (3X) gives autopilot technology the reliability necessary to safely carry out sensitive flight missions and transport valuable payloads. A triple redundant arrangement is comprised of three similar software and hardware systems. If any one of the three systems fails, the remaining two take over, offering a double redundancy arrangement. If one of the other two systems should fail, the third takes over. An additional mechanism is also included to oversee these three systems. Triple redundant systems are highly tolerant of autopilot hardware failures.

Triple redundant autopilots are not new. Military aircrafts such as the RAF’s Trident fleet, used a triple redundant autoland systems in the early 1960’s. Ten years later, the Aérospatiale-BAC Concorde took advantage of 3X technology in its flight control system. Presently, triple redundancy is used in several manned military and commercial  aircrafts.

Although 3X technology is established within the aviation industry, triple redundant autopilots are a relatively new addition to unmanned areal vehicles (UAVs). MicroPilot, the leading UAV autopilot manufacturer, is setting the benchmark for triple redundancy UAV autopilots. MicroPilot, based in Manitoba, Canada, has been designing autopilots for fixed-wing, transitional and helicopter UAVs since 1994. In 2006 MicroPilot started designing a triple redundancy autopilot for heli and fixed wing UAVs. The MP21283x product will launch September 2010.

The MP21283x is comprised of three of MicroPilot’s MP21283g autopilots, mounted on  an adapter board, or redundancy board. The three MP2128 g’s are prioritized. At the start, the autopilot in position one flies the airframe. If this autopilot should fail, the MP2128 g in position two takes over, and so on. The redundancy board provides several input/output (I/O) ports. The board also includes two RS232 serial ports designed to communicate with a ground control system via radio modems. As a result of this design, users never need to work directly with bare circuit boards. Additionally, the autopilots do not have individual casing, keeping overall weight to a bare minimum. However, the entire redundancy board is enclosed to protect the system.


This white paper covers the benefits of the triple redundant MP21283x and what specific conditions this autopilot is designed for. Features of the MP21283x will also  be  explained, including multiple communication links, backup high current drivers, backup power supplies, and independently generated servo signals. Synchronization, modification and testing products will be discussed as well.

Who Needs the MP21283x

Any flight mission that cannot be recovered with the implementation of a flight termination system benefits from triple redundancy. A UAV that comes down over a forest or ocean, for example, is difficult to recover. It is also good judgment to install 3X technology in a UAV that flies over built-up and environmentally sensitive geographic areas.

Additionally, when flying expensive airframes, 3X can help cut losses by minimizing crash damage. Likewise, high dollar payloads are better insured with the installation of the MP21283x. MicroPliot’s 3X solution is also a good choice for large UAVs to avoid the glut of complications that come about when these large vehicles come down. High speed UAVs and those taking long missions also benefit from triple redundant technology. Traveling at high speeds does not allow UAVs time to recover from a failure, considering parachute deployment typically involves a complicated multi stage recovery system.

Identify Failures Quickly

The key benefit of the MP21283x is its ability to quickly detect hardware faults, especially those involving sensors. For example, a rate gyro with a full scale reading of 300 degrees per second, results in an attitude error of 30 degrees in just 100 milliseconds. This miscalculation   could   be   devastating,   especially   if   the   UAV   hovers   next   to you.  Determining sensor discrepancies is no simple matter. Sensor data cannot simply be compared, as noise and phase shift cause correct data to appear faulty.

If your UAV flights call for error-free transitions, the MP21283x is a practical solution. The MP21283x is built to transition vehicle operation seamlessly between autopilots. For example, during takeoff and landing, jumps in control positions can cause damage due to the UAV’s close proximity to the ground. The MP21283x is designed to avoid sudden control inputs, which could cause the UAV to strike the ground. The MP21283x is also design to smoothly transition when a failure takes place on ground or during other critical flight phases (i.e. final approach). Moreover, if failure occurs during initial takeoff roll, the autopilot aborts the takeoff.

Choosing the MP21283x over the MP2128LRC

For those debating between MicroPilot’s MP21283x and the MP2128LRC, here are some tips to help you decide which product best fits your needs. Although the LRC offers such features as redundant radio modems, redundant RC override, integrated radio modems, and a backup microprocessor, the MP21283x may be a better solution. The LRC backup processor allows a backup pilot to fly the UAV manually in the event of a failure; however, completing flights without the autopilot is difficult. For example, manual flight is challenging particularly if the UAV is far from its destination. Not only do flying maneuvers need to be made manually, failures also need to be identified by hand (i.e. the backup pilot must monitor the UAV continuously for failures, allowing for ample recovery time). Due to MP21283x’s redundant features, this product weighs and costs more than the MP2128LRC. Therefore, if weight and price are key factors, the MP2128LRC is a better choice.

MP21283x Ultimate Reliability Measures

In addition to the three MP2128gs incorporated into the MP21283x, MicroPilot’s triple redundant autopilots provide even more backup components. These include provisions for multiple communication links, backup high current drivers, backup power supplies, and independently generated servo signals. Two different types of global positioning systems are also used to improve reliability.

Multiple Communication Links: The MP21283x acts as the UAV’s communication hub. Two radio modems can be installed, which offers two independent lines of communication between the autopilot and the ground control station. Devices such as pan tilt zoom cameras (PTZ) and aircraft transponders (which enable ground control to identify the UAV) can also be connected to the autopilot. The MP21283x’s redundant datalink between the UAV and the ground control station insures the UAV operator can continue to monitor and control the UAV as well as other important on-board equipment even if one radio link fails. The MP21283x switches communication links when flight operation is transferred from one autopilot to another autopilot. This ensures the operator on the ground is always monitoring and controlling the autopilot flying the UAV.  See Figure 2.


To conserve communication channels, non-essential devices, such as data collection systems (i.e an air quality monitor), are connected to only one autopilot. However, critical devices, such as the transponder, are plugged into a communication port that automatically switches between autopilots in the event of an autopilot failure.

High Current Drivers: The MP21283x simplifies its installation with eight high current drivers. The MP21283x can switch devices on and off that take high volumes of current (i.e. navigation lights and landing lights) without additional circuitry. Each of the three MP2128g autopilots is connected to eight high current drivers. These are parallel connections. This arrangement allows any of the autopilots to turn on a high current driver. As long as one autopilot is functioning, any of the devices connected to the high current drivers can be enabled.

Independent Power Supplies: Each MP2128g incorporated into the triple redundant MP21283x has an independent power supply. In addition, separate input pins are installed for power and ground in each backup autopilot. To ensure reliability, no components share a single power supply. Therefore, in the event that a component  fails, only a single autopilot is affected.

Pass or Fail OK Signals: For a triple redundant arrangement to truly function, a part of the system must know if and when an autopilot fails. Otherwise, a dysfunctional autopilot could continue to be in charge of the UAV and eventually drive the aircraft  into the ground. The three individual MP2128gs continuously watch state information from the other two autopilots. Each autopilot uses pulses to let the redundancy board know which autopilots are functioning properly. Based on the pulses the redundancy board receives, the board determines which autopilot operates the UAV.


Other systems that send a variety of signals (or logic levels), indicating different levels of autopilot function, have a higher chance of running into complications. When an autopilot malfunctions in a logic level system, the autopilot generates an OK signal when it should not. Therefore, instead of telling the redundancy board the autopilot is not functioning properly, it leads the redundancy board to believe the autopilot is operating correctly. To counter this, the MP21283x evaluates the pass/fail signal from all  autopilots. In this system, if a pulse is sent other than OK, the autopilot is deemed not working. Pulse timing is also monitored. Out-of-spec pulses are ignored, avoiding readings of misleading OK signals.


Triple GPS: In the event that one or more GPS systems fail, three are present on the redundancy board – two Ublox GPS modules and one Novatel GPS. The primary  autopilot is hooked up to the Novatel GPS module.

All of these aforementioned quality backup measures give the MP21283x the reliability factor UAV operators need to successfully complete sensitive and expensive missions.

Tri-autopilot Synchronization

Synchronization is key to automated flight function. For example, when implementing a target geolocation acquisition (TGA) system, the camera, GPS, and inertial measurement unit (IMU) must be in sync to determine an approximate ground position. Adding to the complexity, a redundant system calls for a whole new level of synchronization. Triple redundancy requires a variety of synchronized data within all three autopilots. There are six forms of data that must be synchronized:

  • Critical state information from feedback loops
  • Ground control data
  • Mission data
  • Scripting language
  • Sensor data
  • Autopilot sanity

The MP21283x incorporates an inter autopilot communication system within the MP21283x. This system synchronizes data and settings among all three autopilots, limits sudden jumps in the control outputs, and synchronizes systems to the same uplink data. “If the operator changes waypoints, targets or altitude, updated data propagates to the remaining autopilots. Without proper synchronization, flight missions can be jeopardized entirely if flight operation is transferred to another autopilot programmed with outdated data,” says Howard Loewen, MicroPilot President.

For example, data shared between ground control station and the flying autopilot must be uploaded to the other two autopilots. If a UAV flying at 100 feet receives an altitude change of 400 feet, this data needs to find its way into the other two MP2128g’s. Otherwise, the UAV returns to flying at 100 feet if control is transferred between autopilots. This could lead to a variety of problems, especially if flying over built-up, or mountainous, areas.

Furthermore, each autopilot must be programmed with the same mission. If not, after switching operation between autopilots, the new autopilot will execute a completely different set of waypoints. The MP2128g missions also include scripting language that allows MicroPilot customers to easily restructure their operations. These commands can have several states and/or modify the internal state of the autopilot. Synchronizing these commands on all three autopilots ensures states are kept consistent in the event of an operation transfer between autopilots.

Supporting Products

MicroPilot’s UAV autopilots are available with a complete suite of development tools. MicroPilot modified several of its auxiliary products to support the MP21283x. For example, its update program was simplified to more efficiently renew data stored in three separate autopilots. Horizonmp and in-the-loop simulator programs are also members of MicroPilot’s suite of MP21283x development tools.

HORIZONmp: MicroPilot’s ground control station software, HORIZONmp, includes a built-in software in the loop simulator. To provide the most realistic level of simulation, the SWIL is designed to accurately simulate three autopilots, as opposed to one. This simulation product also tests the inter autopilot communication system incorporated into the 3x.

qHWIL Simulator: MicroPilot includes a quasi hardware in the loop simulator. This MicroPilot product injects sensor data and retrieves servo positions through a serial port. The qHWIL simulator provides simulator data for three separate autopilots.

trueHWIL Simulator: MicroPilot provides a trueHWIL solution for all of its autopilots. This product inserts sensor data and retrieves control information electronically, providing the highest fidelity simulation available in the industry. The trueHWIL is designed to provide independent sensor data to all three autopilots.

Future Products

While the MP21283x provides the highest reliability UAV autopilot  system  and supporting products available to date, MicroPilot continues to improve its triple redundancy suite. For example, future MP21283x products will incorporate sensor sharing. With this feature, if an autopilot loses one of its sensors, it can still fly the UAV by accessing data from another autopilot’s sensor within the redundant system. As a result, sensor failures become less serious.

Dual autopilot redundancy is another feature MicroPilot is currently perfecting. With  this system, an MP21283x operating on only two autopilots is better equipped to detect  a partially failed autopilot.

Triple Confidence

MicroPilot’s MP21283x offers the high degree of redundancy UAV operators need to conduct UAV flights over geographical areas that offer little hope for recovering a lost

vehicle. When flight termination systems are not enough to protect your assets,  whether they are expensive airframes or high- dollar payloads, a triple redundancy autopilot is worth the investment. “Three autopilots, dual radios, power device backups, and reliable servo signals are a few of the features the MP21283x offers UAV manufacturers and operators,” says Loewen. “We kept our sights high when we designed our new triple redundant autopilot and supporting products.” Let the technology behind the MP21283x give you the assurance required to lift off.

For more information on MicroPilot’s autopilots, please visit my MicroPilot page at www.uavpropulsiontech.com/micropilot.

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