Aircraft Flight Manual

Version 1.0

Last Updated: June 2015
Page 2

CONTENTS

GENERAL INFORMATION

OPERATING LIMITATIONS

NORMAL PROCEDURES

EMERGENCY PROCEDURES

AIRCRAFT AND SYSTEM DESCRIPTION

HANDLING, SERVICE AND MAINTENANCE
Page 3

GENERAL INFORMATION

INTRODUCTION

Congratulations on selecting a small unmanned aerial system (sUAS) from PreNav. This manual will serve as your 

guide in learning how to operate the most precise commercial drone available on the market today. 

The PreNav system has been purpose-built for flight along vertical structures, and in environments that are either 

GPS-denied or that require considerable levels of autonomy and precision. 

THE SYSTEM

The PreNav system consists of a ground-based Laser Guidance System (LGS), multi-rotor aircraft, and ground control 

software (GCS) on a laptop or tablet. The system gains environmental understanding by scanning a region from the 

ground before flying, and then tracking the drone from that same location. This allows the drone to be guided along 

a pre-planned trajectory through the environment. 

The PreNav system operates under a few guiding principles:

1.) No manual piloting required. The aircraft should be capable of flying its entire mission without operator 

intervention. 

2.) Spatial awareness is key. PreNav focuses on understanding the environment before and during flight to 

complete missions safely and efficiently.

3.) Precise control of the aircraft leads to better results. PreNav’s Laser Guidance System enables the drone to 

follow a pre-defined path with precision, which leads to consistent, repeatable data capture.

PARTS

Laser Guidance System (LGS): The LGS is used to scan the environment and provide position updates to the drone as 

it flies, essentially guiding it around the environment.

Multirotor aircraft: The aircraft flies through the environment capturing photos, videos and other sensor data as 

required by the mission. The aircraft receives mission commands from the GCS and precise position updates at a high 

rate from the LGS.

Ground Control Software (GCS): The GCS is used for planning each mission in advance, observing mission status 

information during flight, and visualizing imagery that’s being collected by the aircraft. 
Page 4

Other Components:

● Battery kit (battery, guard bag, and charger with international travel adapters)

● Propellers (spare propellers, tool kit)

● Camera system and gimbal (hi-res camera, 3 axis gimbal, sd card)

BATTERY CHARGING

The Laser Guidance System and multirotor aircraft are powered by rechargeable lithium polymer (LiPo) batteries. Store the 

batteries at half charge then charge fully before flying. Batteries must ship at half charge, so please charge before your first 

flight. The battery configuration provides up to 16 minutes of flight time (NOTE: Flight time varies with payload, wind 

conditions, altitude, temperature, humidity, and mission type). See the Flight Checklist for instructions on managing battery 

levels during flight.

Battery Safety 

Protect the battery from extreme heat, extreme cold, puncturing, and flammable surfaces. Always transport, charge, 

and store the battery in the guard bag. Charge the battery using a designated LiPo balance charger only. Always 

monitor the battery while charging. Flying with a low battery is a safety risk and can render the battery unusable. 

Always discontinue use when you receive a low battery notification, and always begin flight with a fully charged 

battery. Inspect the battery for damage before takeoff and after landing. If you observe any swelling of the package 

or the battery ceases to function, locate your local battery recycling center to dispose of the battery. In the US and 

Canada, visit call2recycle.org to find a location. Do not dispose of the battery in the trash.

Charge the battery using the provided charger only.

SAFETY

The PreNav drone has powerful motors and high-speed propellers. Never place your hands near propellers while the 

drone is armed. Do not fly over people who are not participating in the mission, near airports, or in any situation that 

could pose a hazard to those around you. Always fly within your line of sight and in compliance with local regulations. 

The PreNav drone will avoid obstacles that have been pre-scanned; however, the scanner cannot pick up every

obstacle, so as the operator, it is your job to recognize and avoid obstructions while flying. Always follow the preflight 

and post-flight steps in the order described in this manual, and remain attentive at all times while flying. 

Environmental factors, such as wind and GPS irregularities, can cause instability in flight. The PreNav drone will 

attempt to compensate for these factors by triggering a failsafe if it detects an unsafe flying condition due to loss of 

command and control signal, loss of GPS signal, or low battery (see below for details). To avoid potential hazards due 

to environmental factors, identify the boundaries of your flying area before takeoff. If you observe any inconsistent 

behavior, land, and consult the troubleshooting guide.
Page 5

CONTROLS

Controlling the PreNav system is simple. The following controls are available for any given mission:

● Pre-flight

○ Power - turns on the LGS

○ Select/Drag - adjust the geofence within the GCS

○ Set Geofence - saves the geofence within the GCS

○ Scan - begins the environment scan with the LGS

○ Set Waypoint - doubletap within the GCS to set 3D waypoints

○ Approve - saves and uploads the flight plan to the aircraft 

● Flight

○ Power - turns on the aircraft

○ Activate - turns off the safety and makes the aircraft ready to receive commands

○ Arm/Disarm – begins/stops spinning the motors

○ Fly - begins the flight. This option is only available if the environment has been scanned, a path 

planned, and the LGS is actively tracking the aircraft.

○ Pause - pauses the aircraft mid-flight in its current location along the path

○ Speed up / Slow Down – increases or decreases the rate at which the flight path is being traversed

○ Return to Launch - returns the aircraft to the launch point, following a pre-calculated safe path 

through the scanned environment

○ Emergency Land in Place - lands the aircraft in place immediately by reducing thrust to the motors

OPERATING LIMITATIONS

INTRODUCTION

This section contains only those limitations necessary for the safe operation of the UAS. 

AIRSPEED LIMITATIONS

Minimum Operating Airspeed: 0 knots

Maximum Operating Airspeed: 30 knots

ALTITUDE LIMITATIONS

Minimum Operating Altitude: -100 ft (MSL)

Maximum Operating Altitude: software limited to 500 ft AGL as determined by LGS altitude estimate
Page 6

PROPELLER LIMITATIONS

Maximum Propeller RPM: 9700

Minimum Propeller RPM: 0

ENVIRONMENTAL LIMITATIONS

IFR LIMITATIONS

IFR flight not allowed.

TEMPERATURE LIMITATIONS

AIRCRAFT

• Minimum Operating Temperature – Aircraft: -40°F

• Maximum Operating Temperature – Aircraft: 140°F

LGS

• Minimum Operating Temperature – LGS: -40°F

• Maximum Operating Temperature – LGS: 140°F

WIND LIMITATIONS

Maximum Wind Velocity – 25 knots

PRECIPITATION LIMITATIONS

Should not operate in precipitation. 

HUMIDITY LIMITATIONS

Ideal operation range is 30 - 70% relative humidity. Operation extremes from 0 - 100% relative humidity. 

ICING LIMITATIONS

Should not operate in conditions where ice may form. 

LIGHTNING LIMITATIONS

Not safe to fly near lightning.
Page 7

NORMAL PROCEDURES

INTRODUCTION

Operating a PreNav system is straightforward. Follow these in the order shown here every time you fly:

OPERATIONS AREA AND LGS ASSEMBLY/PRE-FLIGHT

1. Evaluate your flight operations area and mission target (e.g. the structure, building, etc.) to make 

sure you can prevent flying over people or in hazardous conditions.

2. Select a level area within 20-80 feet of the mission target, making sure it has an unobstructed view of 

the target. This will serve as the launch area. Place the multi-rotor aircraft in the launch area, using 

the following table as a guide:

Tower height (up to) Aircraft and LGS distance from 

tower

100 feet 20 feet

200 feet 40 feet

300 feet 60 feet

400 feet 80 feet

3. Install Laser Guidance System (LGS) on tripod, ensuring LGS is hand tightened onto tripod.

4. Place LGS approximately 5 feet behind the aircraft in the launch area, and face the LGS towards the 

aircraft and mission target (make sure the arrow on the front of the LGS is pointing towards the 

drone and structure).

5. Insert a fully charged battery tray into the LGS and power on the device.

AIRCRAFT SYSTEM ASSEMBLY/PRE-FLIGHT

1. Inspect multi-rotor aircraft for cracks and damage. Check for loose bolts and equipment. Check that 

motor mounts are tightened securely. Check that arms are firmly attached. Check that antennae are 

firmly attached.

2. Check propellers are mounted securely and check for defects: cracks, chips, etc.

3. Check that the battery is fully charged.

4. Check the battery is installed properly and securely.

5. Turn on aircraft. 

6. Keep the aircraft still and level while it powers on and initializes the sensors.
Page 8

SYSTEM PREFLIGHT AND TESTS

Geofence

1. Turn on the tablet or laptop, and open the PreNav Ground Control Software (GCS) app. 

2. The system will geolocate your position on a map, and the GCS will create a default geofence with a 

120 meter radius. The aircraft will not be allowed to fly outside of the geofenced area under any 

circumstances. 

3. Take note of any hazards or populated areas, and adjust the geofence to exclude those areas as 

necessary. Press “Set” to save the geofence.

Scan

4. Press the large “Scan” button on the LGS or GCS, and the system will capture a panoramic image of 

the environment

5. From within the panorama on the GCS, select the structure or area that you would like to scan. Press 

“Scan” and you will begin to see the point cloud environment building within the GCS

6. Press “Stop” once you have sufficient resolution to fly with confidence in the environment (usually 

takes between 5 and 10 minutes).

Plan

7. Draw or load your flight path (e.g. tower path, turbine path, rooftop path, etc.) within the GCS

8. Drag the waypoints of the path around within the GCS interface until you are satisfied with the flight 

path. PreNav algorithms will ensure the path is achievable and obstacle-free.

TAKEOFF

1. Verify the area is clear around the aircraft, and clear between the LGS and the tower.

2. Make sure each motor/propeller on the aircraft is free from obstructions and people.

3. Press the safety button on the aircraft, and wait for the GCS to indicate that it is ready to be armed. 

4. Toggle the ARM switch on the GCS to the ARM position and wait for the green light, indicating the 

units have passed internal checks. If using a tablet, verify the ‘Preflight checks passed’ is visible on 

the screen. The propellers will spin when armed. Ensure that the launch point is clear of 

obstructions and people before arming. Always disarm the motors before approaching the aircraft.

5. To start the mission, press the “Fly” button on the LGS or the tablet.

Ensure that the GCS is always turned on while the aircraft is powered, otherwise if the aircraft loses 

communication with the GCS in flight, it will initiate an automatic return to launch.

LANDING

1. The system will automatically land once the flight plan is completed.

NOTE: The system has built in safeguards to return to launch or autoland in the case of emergency. 

However, if you experience an unexpected emergency and the aircraft does not appear to be reacting 

with a built in failsafe, press the return to launch button or emergency land button to immediately end 

the mission.
Page 9

SHUTDOWN

SHUTDOWN – CHECKLIST

1. Wait until the aircraft lands and powers down motors. The motors will disarm automatically after the 

mission is completed. 

2. Once the motors have stopped spinning, press the safety button on the aircraft to make it safe for 

handling. 

3. Turn off power switch on aircraft.

4. Disconnect the battery on the aircraft.

5. Power off the GCS.

6. Turn off power switch on LGS and disconnect the battery from LGS.

7. Remove the SD card from the camera, and upload the photos at PreNav.com to be processed

AIRCRAFT SYSTEM DISASSEMBLY/POSTFLIGHT

AIRCRAFT SYSTEM DISASSEMBLY/POST-FLIGHT – CHECKLIST

1. Remove batteries from aircraft and LGS and place in battery fire-safe bags.

2. Inspect propellers and landing gear for damage.

3. Inspect motor and motor arms for damaged or loose fittings.

LGS AND AIRCRAFT BATTERY CHARGING

1. Connect batteries to approved charging device.
Page 10

EMERGENCY PROCEDURES

INTRODUCTION

This section contains checklists describing the recommended procedures and airspeeds for coping with various types 

of emergencies or critical situations. Checklist reflect the sequence of critical pilot actions. 

The system consists of three parts: the aircraft, the Laser Guidance System (LGS), and a laptop computer or tablet 

based GCS. The LGS and GCS are part of the control system, and include buttons for emergency procedures. There are 

no manual flight controls (like joysticks) on the LGS. The buttons on the LGS are 1) return to launch - flies a safe path 

back to take off point, 2) emergency land in place - descends vertically to the ground, 3) engine stop - kills the 

engines. These buttons are also available on the screen of the GCS.

AIRSPEEDS FOR EMERGENCY OPERATIONS

Emergency procedures can be initiated at any airspeed.

ENGINE FAILURE

1. The aircraft automatically descends vertically at a controlled rate if an engine failure is detected. No 

action from the pilot is required.

AIRCRAFT LOSES CONTROL SIGNAL FROM LGS OR GCS

1. The aircraft automatically descends vertically at a controlled rate if the signal from the LGS or GCS is 

lost for a period of time. No action from the pilot is required.

LOSS OF LGS ELECTRICAL POWER

1. The aircraft automatically descends vertically at a controlled rate if the signal from the LGS is lost for 

a period of time. No action from the pilot is required.

LOSS OF GPS DATA

1. If GPS signal is lost coincident with loss of LGS signal, the aircraft descends vertically. 

2. Loss of GPS signal by itself does not affect aircraft operation.

AIRCRAFT FIRE ON THE GROUND

1. Press the ‘engine stop’ button on the LGS or tablet.

2. Clear area of non-essential personnel.

3. Extinguish the fire using appropriate methods. 

AIRCRAFT FIRE IN-FLIGHT

● OVER SAFE LANDING ZONE: If the aircraft is positioned above a landing area that is deemed safe, 

press the ‘engine stop’ button. 
Page 11

● OVER UNSAFE LANDING ZONE: If the aircraft is positioned over an unsafe landing area, press 

‘return to launch’ button on LGS or tablet and once the aircraft is over a suitably safe landing area, 

press the ‘engine stop’ button.

LOSS OF AIRCRAFT ELECTRICAL POWER

1. Loss of complete electrical power to the UAV results in an immediate and uncontrolled landing. 

2. Locate the aircraft and disconnect the battery, if able to do so safely.
Page 12

AIRCRAFT AND SYSTEM DESCRIPTION

INTRODUCTION

This section describes the aircraft and all associated systems in a manner appropriate to the pilot most likely to 

operate the aircraft. 

AIRCRAFT

Frame type: carbon fiber 

Dimensions:

• Overall Length: 2.5 ft

• Overall Height: 2.5 ft

• Overall Width: 2.5 ft

• Rotor Diameter: 1 ft

Motors: 8 DC Electric Outrunner motors manufactured by KDE, 775 kV, X8 configuration 

Propellers: 12 inch carbon/composite 2-bladed propellers

Battery: two Turnigy Nano-Tech 8400 mah / 40-80C discharge lithium polymer 

Flight time: Approx. 16 minutes, depending on conditions, mission requirements 

Electrical System Components: Battery, Electronic Speed Controllers, Motors, Flight Controller.

Landing Gear System: Four fixed gear landing struts. The struts are composed of a flexible material. 

Aircraft Lighting System: An array of LEDs are placed on the outward face of the motors. 

AIRCRAFT RADIOS

Aircraft communications: Control system uses both 2.4 GHz and 5 GHz radios to allow the aircraft and LGS to 

communicate. The 5 GHz Wi-Fi radio is used to transmit imagery from the aircraft to the LGS. 

AIRCRAFT FLIGHT REFERENCE/NAVIGATION SYSTEMS

GLOBAL POSITION SYSTEM (GPS)

GPS Description: A single GPS receiver connected to an external antenna. 

INERTIAL NAVIGATION SYSTEM (INS)

INS Description: Solid-state INS using 3-axis accelerometer/gyroscope. A static pressure sensor measure barometric 

altitude.

MAGNETOMETER

Magnetometer Description: There are two magnetometers, an internal and an external. 
Page 13

AIRCRAFT AUTOPILOT SYSTEM

Aircraft Autopilot System: Modified Pixhawk system. The autopilot is integrated into the control system and not 

usable by the pilot.

CAMERA AND PAYLOAD SENSOR SYSTEMS

CAMERA SYSTEM

Camera System: The camera is mounted on a gimbal and is automatically controlled by the system. 

FLIGHT TERMINATION SYSTEMS (FTS)

FTS Description: The FTS is controlled by both the GCS and the LGS, and operation is described in the Emergency 

Procedures section.

PERFORMANCE RECORDING SYSTEM

FLIGHT DATA RECORDING SYSTEM

Flight Data Recording System: Flight data is recorded and logged in the GCS, and uploaded to the cloud services along 

with the imagery. 

LASER GUIDANCE SYSTEM (LGS)

LGS System Description: The LGS is composed of a camera and rangefinder mounted tripod with a gimbal. The LGS 

tracks the UAV with computer vision and sends positions estimates to the UAV through a 2.4 GHz link. 

GPS Description: A single GPS receiver connected to an external antenna. 

Dimensions:

• Overall Length: 2 ft

• Overall Height: 2 ft

• Overall Width: 3.8 ft

Weight: 15 lbs
Page 14

HANDLING, SERVICE AND MAINTENANCE

INTRODUCTION

This section describes the maintenance and inspections recommended by the manufacturer; as well as information of 

the storage and transport of the UAS.

AIRCRAFT

AIRCRAFT INSPECTION SCHEDULE

The aircraft should be inspected before and after each flight. Inspections should include: checking for damage to 

aircraft; loose or damaged fasteners; motors are fastened tightly; propellers are secure and undamaged; battery 

charge.

AIRCRAFT MAINTENANCE SCHEDULE

The aircraft should be inspected before and after each flight, and maintenance to repair any damage or any 

components that are out of spec. Also the battery needs to be balanced approximately once every five flights.

AIRCRAFT STORAGE AND TRANSPORT

The aircraft needs to be stored and transported in a secure box in an upright position, to prevent damage to any of 

the sensor components and to prevent damage to the propellers.

LASER GUIDANCE SYSTEM (LGS)

LGS INSPECTION SCHEDULE

The LGS should be inspected before and after each flight, sensor calibration should be checked.

LGS MAINTENANCE SCHEDULE

The LGS does not need regular maintenance, but should be checked for calibration in the inspections. If any sensors 

are out of calibration or any damage to the LGS occurs, then the LGS should get maintenance.

LGS STORAGE AND TRANSPORT

The LGS needs to be stored and transported in a secure box to prevent damage or de-calibration to any of the sensor 

components. 
Page 15

SUPPORT

For customer support, contact us at help@prenav.com or call our support line at +1 (415) 652-9723 Monday through 

Friday, from 8 am to 5 pm, Pacific Time. 

PreNav, Inc.

887 Industrial Rd., Ste B

San Carlos, CA 94070