The 'uTe' Gyroplane
The Rivaero ‘uTe’ (so-named for its ‘utility’ capability) is an attempt to assimilate, enhance and develop best-practice gyroplane technology onto a single platform and, in so doing, produce a safe, reliable utility gyroplane designed specifically for the more stringent demands of commercial operations.
The major focus throughout the uTe R & D process was ‘adaptabiliity.’ This design philosophy envisages quick & easy conversion between different roles, whether in private, commercial, government-agency or quasi-military operations. Although very well-suited for recreational flying, the new Rivaero uTe has been specifically designed and built to be utilised in special purposes operations – wherever a rugged, work-horse gyroplane may be required.
Innovation is one of the key driving forces behind our design philosophy at Rivaero and the new uTe prototype is brimming with innovative ideas and features:
Initial digitizing ‘point-cloud’
The parts store – ready to populate!
Special Purpose Operations
In addition to the rear seat / dual flight-control system (the ‘standard’ configuration), the rear cockpit features a unique equipment changeover system.
Spacious interior & easy access
This allows uncomplicated, rapid conversion between the various special purpose equipment systems, available as optional extras, according to customer requirements and specifications. The rear seat-mounting hardware is of a common design with the mounting-system affixed to the base of all the various, modular equipment-suites, designed to be accommodated in the rear-cockpit:
- Various data-capture equipment and mast-mount transmitter/receiver antenna options.
- A range-extending, 50 ℓ fuel-tank, which provides a 2 hour increase in endurance.
- A 100 ℓ utility-equipment crate which is designed for the ferry of light tools and equipment, but is equally capable of accommodating extra baggage, spare parts, fuel ‘jerry-cans,’ camping gear, etc.
- A 200 ℓ spray tank coupled with various, purpose-made aerial-baiting or ‘crop-splashing’ spray-boom array options.
- Aerial-release machine options, capable of metered release of sterile insects (Mediterranean fruit-fly, false codling moth and tsetse-fly species) as well as pellet-pesticide used to control unwanted pest- & invader-plant species, etc.
- Airborne survey equipment (ground-penetrating ‘radar’) options.
Mast & keel manufacturing
Composite, aluminium frame sub-assembly
The uTe airframe consists of triple-redundant, resilient, lightweight, aluminium sub-assemblies extruded from tough, heavy-duty, corrosion-resistant 6061-T6 aluminium alloy.
The individual rectangular-tube sections are bonded together using adhesive tape and the resulting composite framing members are then bolted together using extremely-strong ‘cluster-plates,’ to form a robust, durable keel & mast combination to which the GRP composite landing-gear is attached.
All bolts used in the primary structure of the rotorcraft are of the best-quality ‘AN’ (Army & Navy) specification hardware.
Benefits of such a design are:
- Safety: welded steel (particularly stainless-steel) frame-sections, utilised as the basic structure of many extant gyroplanes, often tend to fail at welds which ‘hides’ weld-failures from easy detection with the naked eye during routine inspections! To identify faults, weld-failures and cracks, frame sub-assemblies must often be periodically disassembled, and submitted to crack-testing. Welds are also notorious rust-propagation areas, while 6061-T6 aluminium is rust-proof.
- Manufacture: apart from the cluster plate attachments at the frame and keel extremities, only one of the rectangular sections is drilled when fitting sub-assemblies! The integrity of the pair of ‘side-by-side’ extruded rectangular sections is not altered in any way during assembly.
- Maintenance: multi-member aluminium sub-assembly design means wear or damage can be easily detected during routine inspections, allowing prompt replacement of only damaged sub-assembly components, reducing ‘down-time’ & maintenance costs.
- Failure: triple-redundancy (since each of the three rectangular sections is able to carry normal flight loads on its own) precludes the occurrence of catastrophic primary-structure (keel or mast) failures.
GRP & CRP Fuselage Nacelle Fitting
The cockpit is enclosed by a high-quality, exceptionally-strong, composite fuselage. Many gyroplanes available today are fitted with a flimsy ‘fairing’ aimed at improving the airflow and aesthetics around the cockpit area. The uTe sports an attractive, durable, lightweight, CRP, GRP and Polycarbonate cockpit nacelle, which is resilient enough to offer the pilot a significant measure of protection in the event of a survivable crash-event.
The aircraft can also be operated in a number of different cockpit configurations:
In the fully enclosed configuration, the uTe provides cockpit comfort-levels usually associated with much more-expensive, general aviation aircraft, while the option of removing the rear pair of cockpit enclosure doors improves rear-cockpit visibility and utility.
There is also the option of removing all four cockpit enclosure doors, creating a completely open-cockpit option.
Whether you are looking for more comfortable conditions on those cold, early-morning, cross-country flights or, alternatively, the experience of flight in the true, open-cockpit aviation tradition, the uTe fuselage options cater for every motivation!
The shape, location and dimensioning of the uTe empennage are of precise aerodynamic determination. The airfoil design and incidence of the large horizontal stabiliser (an inverted NACA 2210 profile) compensates for the increased down-force ahead of the aircraft centre-of-gravity as airspeed increases, most notably at higher power settings.
The horizontal stabiliser generates progressively-increasing down-force (negative lift) as airspeed increases, thereby automatically providing a force of the correct magnitude and orientation behind the aircraft centre-of-gravity, to keep the aircraft longitudinally-stable throughout the flight envelope!
Directional stability is accomplished by having ample vertical surface-area designed into the empennage. This counteracts the considerable forces caused by airflow impinging on the large, closed cockpit structure should the aircraft be flown considerably out-of-balance. In such a scenario, the three generously proportioned vertical stabilisers keep the aircraft properly longitudinally-orientated!
The large vertical tail-surfaces and rudder also allow positive directional control in the hover-descent at low power settings, eliminating the uncontrolled yaw that many other gyroplanes experience in this flight-regime.
Manufacturing the Blade Mould
The aim of our ongoing rotor-research and design effort has been aimed at selecting a rotor of optimum planform, profile, diameter and chord-length for the uTe, which ensures the best possible fit with as many of the rotor optimisation criteria as possible.
Rivaero initially attempted to have our own blade design extruded but, as a result of manufacturing inconsistencies, this process had to be abandoned in favour of, instead, manufacturing GRP/CRP blades from which uTe gyroplane rotor-sets are manufactured. Modern, composite-manufacturing techniques also allow significant freedom to incorporate many best-practise design criteria which have become evident from recent research into auto-rotating rotors.
Rivaero rotor-blades feature a modified NACA 8-H-12 aerofoil profile, incorporating a thinner, optimised profile & planform, with zero resolved pitching moment coefficients.
Where this blade operates in the ‘Driving Region,’ the blade is of uniform planform and section profile. The outer 750 mm of the blade span (in the ‘Driven’ region), however, is of elliptical planform for reduced profile-drag and improved performance, while reducing the total blade area only very-slightly. Further outboard, beyond 500 mm from the tip, the blade undergoes a ‘Change of Section’ to a thinner, more-cambered NACA 4405 tip-profile, which is designed to delay the onset of retreating blade stall (RBS) at higher airspeeds. This profile has been given the designation ‘RIV-G1-11.’
Elements of the RIV-G1-11 Rotor-blade, showing the Lead (Pb) L.E. & tip weights, the GRP spar and CRP skin)