Robbe K-Rati II Pro: Assembly and User Manual

Preface

The K-Rati II Pro can be flown within a broad speed range. The solutions stated in this manual are recommendations, as construction preferences may vary. The PNP (Plug and Play) version is largely prefabricated, while the ARF (Almost Ready to Fly) version requires modeling experience and basic technical skills. This manual provides guidance for achieving excellent flight performance.

Please read this manual carefully before you start assembling the model!

Flight Instructions

• Before the first flight, observe the safety instructions.
• Choose a day with minimal wind for the first flight.
• Select a large, flat area without obstacles for initial flights.
• Perform a functional test of the drive train and remote control.
• After assembly, re-check that all components (wing, tail units, mounts, engine, linkages) are securely fastened.
• For hand starts, a helper is recommended.
• Start against the wind.
• Avoid stalling the model near the ground.
• Do not initiate tight turns close to the ground.
• Check model reactions to rudder deflections and adjust as necessary after landing.
• Establish minimum flight speed at an adequate safety altitude.
• Initiate landing with sufficient speed.

General Safety Information

Carefully read all safety instructions before operating your model. Always follow recommended procedures and settings. If you are new to remote-controlled models, seek assistance from an experienced pilot. Remote-controlled models are not toys; individuals under 14 years of age must be supervised by adults. Construction and operation require technical understanding, careful craftsmanship, and safety awareness. Errors or negligence can lead to significant damage or injury. The manufacturer and seller are not liable for improper construction, assembly, or operation. Rotating parts (propellers, motors) pose a constant risk of injury; avoid contact. Motors and controllers can reach high temperatures; avoid contact. Never be in the danger area of rotating parts with an electric motor and connected battery. Overcharging or incorrect charging can cause batteries to explode; ensure correct polarity. Protect equipment from dust, dirt, and moisture. Avoid excessive heat, cold, or vibration. Use only recommended chargers and charge batteries for the specified time. Always check equipment for damage and replace with original spare parts. Do not use damaged or wet equipment. Only use recommended components and accessories. Do not modify remote control systems unless described in the instructions.

General Information

• The model is designed for specified components. Servos and electronic components are for standard supply voltage unless stated otherwise. Lipo battery cell count refers to 3.7V per cell. Verify compatibility if using different components.
• Before construction, set servos to neutral by switching on the transmitter and centering sticks and trims (except throttle). Connect servos to receiver outputs and power them. Refer to the receiver and transmitter manuals.
• Do not leave the model in direct sunlight or in a vehicle for extended periods, as high temperatures can deform plastic parts or blister covering foils.
• Before the first flight, check wing, tail unit, and fuselage symmetry. Ensure equal spacing and angles.
• Rebalance propellers if vibrations occur during motor run-up.
• Minor bubble formation in covering foils is normal and can be removed with a foil iron or hairdryer.
• Carefully remove any production burrs on shell-constructed models (GFRP/CFRP) with fine sandpaper or a file.

Safety Note for Model Operation

Attention, danger of injury!

• Maintain a safe distance from your model aircraft.
• Never fly over spectators, other pilots, or yourself.
• Perform flight maneuvers away from the pilot or spectators.
• Never endanger people or animals.
• Never fly near power lines or residential areas.
• Do not operate the model near locks or public shipping routes.
• Operate the model only in approved locations, not on public roads, motorways, paths, or squares.
• Do not operate the model during thunderstorms.
• Check your remote control system for function and range before each flight.
• Remove all batteries from the model after flying.
• Do not aim the transmitter antenna directly at the model during operation; position it to the side.

Use of devices with image and/or sound recording function: If your model is equipped with recording devices, be aware that using the recording function may violate privacy. Overflying or operating on private property without permission can also be considered an invasion of privacy. You, as the operator, are solely responsible for your actions and must comply with all applicable legal requirements.

Safety Instructions for Controllers

• Observe the controller's technical data.
• Observe polarity of all connection cables.
• Avoid short circuits.
• Install or package the regulator to prevent contact with grease, oil, or water.
• Use effective interference suppression measures (e.g., capacitors) on the electric motor.
• Ensure adequate air circulation.
• Never reach into the propeller's turning circle during start-up (risk of injury).
• Dealing with model aircraft and vehicles requires technical understanding and safety awareness. Incorrect assembly, adjustment, or use can lead to injury or property damage. Sudden motor starts can cause injury from rotating parts like propellers. Stay clear of rotating parts when the power source is connected. Ensure all drive components are securely mounted during function tests. Use only within technical specifications and for RC hobby applications. Check speed controller compatibility with your motor and power source. Never operate speed controllers with external power supply units. Protect controllers from dust, moisture, vibration, and mechanical stress. Even splash-proof or waterproof equipment should not be permanently exposed to moisture. Avoid high operating temperatures or poor cooling; maintain recommended temperature range (-5°C to +50°C). Ensure correct connection and avoid reverse polarity. Never disconnect the device from the motor or battery during operation. Use high-quality, high-capacity plug systems. Avoid sharp bends or tensile stress on connecting cables. Disconnect the flight battery after use to prevent deep discharge and permanent damage. For BEC versions, ensure BEC power is sufficient for servos. Install controllers as far as possible from other remote control components. Perform range tests before operation. Regularly check the controller for function and visible damage. Do not operate if damaged. Do not extend connection cables, as this can cause malfunctions. Despite safety devices, damage not covered by warranty may occur, and warranty is void if modifications are made.

Important Information: The receiver system is powered by the controller's built-in BEC system. For commissioning, set the throttle stick to "Motor off", switch on the transmitter, then connect the battery. To switch off, disconnect the battery-controller connection first, then turn off the transmitter. During functional tests, set rudder servos to neutral and ensure the throttle stick is in the lowest position. Follow instructions for all components, batteries, and chargers. Regularly check motor mount bolts for tightness.

Safety Instructions for Rechargeable Batteries

• Do not immerse batteries in water or other liquids.
• Do not heat, throw into fire, or microwave batteries.
• Do not short-circuit or charge with reversed polarity.
• Do not subject batteries to pressure, deform, or throw them.
• Do not solder directly on the battery.
• Do not modify or open batteries.
• Only charge batteries with suitable chargers; never connect directly to a power supply unit.
• Never charge or discharge batteries or chargers on flammable surfaces.
• Never leave batteries unattended during charging or discharging.
• Never charge or discharge batteries in direct sunlight or near heaters or fire.
• Do not use batteries in areas with high static discharge.

Failure to comply can result in battery damage, explosion, or fire! Keep batteries away from children. Keep leaked electrolyte away from fire, as it is flammable. If electrolyte gets into eyes, rinse immediately with plenty of water and seek medical attention. Electrolyte can be washed from clothing and other items with water. Observe battery and charger manufacturer safety instructions.

Warranty

Robbe Modellsport articles have a 24-month warranty. For warranty claims, contact your dealer. Defects in function, manufacturing, or materials will be rectified free of charge. Further claims, such as for consequential damages, are excluded. Transport to Robbe must be free of charge; return transport is also free. Unpaid shipments will not be accepted. Robbe is not liable for transport damage or loss. Appropriate insurance is recommended. To process warranty claims, provide proof of purchase, confirm operation according to the manual, use only recommended power sources and original accessories, and ensure no moisture damage, external interference, reverse polarity, overloading, or mechanical damage has occurred. Include relevant information for fault diagnosis.

Disclaimer

Robbe Modellsport cannot monitor compliance with assembly and operating instructions, or the conditions and methods for installation, operation, use, and maintenance of model components. Therefore, no liability is accepted for losses, damage, or costs arising from or connected with incorrect use and operation. Liability for damages is limited to the invoice value of the Robbe products directly involved in the damage-causing event.

Insurance

Ground-based models are typically covered by personal liability insurance. Additional insurance or an extension is required for aircraft models. Check your insurance policy and obtain suitable coverage if necessary.

Conformity

Robbe Modellsport declares that this device complies with the essential requirements and relevant regulations of the CE directives. The original declaration of conformity can be found at www.robbe.com. This product can be operated in all EU countries.

Disposal

This symbol indicates that electrical and electronic devices must be disposed of separately from household waste at the end of their useful life. Dispose of the device at your local municipal collection point or recycling center. This applies to all EU countries and other European countries with separate collection systems.

Technical Data

Span / Envergure: 2000 mm

Length / Longueur: 1140 mm

Weight (dry) approx. / Poids (vide) env.: 1650 g

Wing Area / Surface des ailes: 31 dm²

Airfoil / Profil: Robbe Special

Center of Gravity (C.G.) / Centre de gravité: 67-70 mm behind the leading edge

Control Throws / Débattements:

Elevator Angle of Incidence: Approx. 1-1.5° (depending on CG). Simpler: with fuselage level, elevator end rail should be approx. 61mm height.

Assembly and Tuning Process

Follow the step-by-step instructions with diagrams for assembling and tuning your K-Rati II Pro. Key steps include:

• Fuselage Assembly: Installing servos, connecting linkages, routing servo cables, and securing components.
• Wing Assembly: Connecting wing halves with the connector, securing with multilocks or tape, and routing servo cables.
• Tail Assembly: Attaching elevator and rudder, ensuring proper alignment and securing with glue or pins.
• Motor and ESC Installation: Mounting the motor, connecting the ESC, and ensuring clean cable routing.
• Battery and Receiver Installation: Securing the battery with Velcro and marking its position for CG adjustment. Installing the receiver and connecting servos.
• Center of Gravity (CG) Adjustment: Determining the correct CG position (67-70mm from the leading edge) and adjusting battery placement accordingly.
• Control Surface Adjustment: Setting control throws for ailerons, elevator, and rudder for normal, speed, thermal, and landing modes as specified.
• Final Checks: Ensuring all connections are secure, cables are tidy, and the model is ready for its first flight.

First Flight Recommendation: Choose a day with suitable weather conditions. Perform the first flight with a starting helper. Enjoy your new model aircraft and happy landings!