Proxflyer
Encyclopedia
Proxflyer refers to a family of micro R/C helicopter prototypes based on a dual coaxial counter-rotating rotor
concept developed and patented by Norwegian Petter Muren. The concept differs from the swashplate
designs in conventional helicopter flight controls and enables a helicopter to be passively stable in hover. Elimination of the conventional cyclic and collective pitch controls
allows for simpler and lighter helicopters to be developed. A helicopter based on this design achieves stability without the use of gyroscopes or any form of active stabilization and thus is made up of much fewer parts than other model helicopters. The two counter-rotating rotors keep the helicopter very stable relative to the surrounding air. Altitude control is performed by varying the speed for both main rotors while Yaw control is achieved by increasing the speed of one rotor and reducing the speed of the other rotor by the same amount. A horizontally oriented tail rotor controls the helicopter’s forward or backward movement by shifting its center of lift with respect to the center of gravity
(CG).
1. The typically 4-bladed rotor has a generally fixed geometry and it is tiltably connected to the rotor shaft enabling the rotor to tilt almost freely in any direction.
2. Furthermore, the outer parts of the rotor blades have a pitch angle that is fixed relative to the rotational plane of the rotor (the tips are fixed to a ring encircling the rotor).
3. Finally the inner part of the rotor blades have a pitch angle fixed relative to a reference plane perpendicular to the rotor shaft (to be able to do this the blades are flexible and can twist in the longitudinal direction).
This combination of features enables the rotor to respond to aerodynamic forces and tilt in any direction without introducing mechanical bending forces between the rotor and the rotor shaft. At the same time it is possible to control the rotor by tilting the rotor shaft (helicopter) in the desired direction of flight. The forward speed is however limited because the rotors have a high tendency to tilt up to counteract any horizontal movement. The rotors increased tilting tendency is an important part of achieving passive stability but it at the same time makes it almost impossible to use this rotor system in a helicopter flying in anything but calm weather. The Proxflyer rotor system is designed for indoor use only and it is claimed to be the rotor system that enables the most stable yet controllable indoor helicopters.
The main benefits are believed to be:
- Passively stable
- Simple electronics without any - Relative simple mechanics
- High efficiency
- Very low noise level
The main limitations are:
- Relative slow forward speed
- Not possible to operate in wind (outdoors)
Contra-rotating propellers
Aircraft equipped with contra-rotating propellers, also referred to as coaxial contra-rotating propellers, apply the maximum power of usually a single piston or turboprop engine to drive two propellers in contra-rotation...
concept developed and patented by Norwegian Petter Muren. The concept differs from the swashplate
Swashplate (helicopter)
A swashplate is a device that translates input via the helicopter flight controls into motion of the main rotor blades. Because the main rotor blades are spinning, the swashplate is used to transmit three of the pilot's commands from the non-rotating fuselage to the rotating rotor hub and...
designs in conventional helicopter flight controls and enables a helicopter to be passively stable in hover. Elimination of the conventional cyclic and collective pitch controls
Helicopter flight controls
A helicopter pilot manipulates the helicopter flight controls in order to achieve controlled aerodynamic flight. The changes made to the flight controls are transmitted mechanically to the rotor, producing aerodynamic effects on the helicopter's rotor blades which allow the helicopter to be...
allows for simpler and lighter helicopters to be developed. A helicopter based on this design achieves stability without the use of gyroscopes or any form of active stabilization and thus is made up of much fewer parts than other model helicopters. The two counter-rotating rotors keep the helicopter very stable relative to the surrounding air. Altitude control is performed by varying the speed for both main rotors while Yaw control is achieved by increasing the speed of one rotor and reducing the speed of the other rotor by the same amount. A horizontally oriented tail rotor controls the helicopter’s forward or backward movement by shifting its center of lift with respect to the center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity...
(CG).
Features and function
The Proxflyer co-axial rotor system utilize the combination of 3 features to achieve passive stability:1. The typically 4-bladed rotor has a generally fixed geometry and it is tiltably connected to the rotor shaft enabling the rotor to tilt almost freely in any direction.
2. Furthermore, the outer parts of the rotor blades have a pitch angle that is fixed relative to the rotational plane of the rotor (the tips are fixed to a ring encircling the rotor).
3. Finally the inner part of the rotor blades have a pitch angle fixed relative to a reference plane perpendicular to the rotor shaft (to be able to do this the blades are flexible and can twist in the longitudinal direction).
This combination of features enables the rotor to respond to aerodynamic forces and tilt in any direction without introducing mechanical bending forces between the rotor and the rotor shaft. At the same time it is possible to control the rotor by tilting the rotor shaft (helicopter) in the desired direction of flight. The forward speed is however limited because the rotors have a high tendency to tilt up to counteract any horizontal movement. The rotors increased tilting tendency is an important part of achieving passive stability but it at the same time makes it almost impossible to use this rotor system in a helicopter flying in anything but calm weather. The Proxflyer rotor system is designed for indoor use only and it is claimed to be the rotor system that enables the most stable yet controllable indoor helicopters.
The main benefits are believed to be:
- Passively stable
- Simple electronics without any - Relative simple mechanics
- High efficiency
- Very low noise level
The main limitations are:
- Relative slow forward speed
- Not possible to operate in wind (outdoors)
Proxflyer Prototypes
| Description | Size | Weight | Flight Duration | Radio Control | First Flight |
|---|---|---|---|---|---|
| Mosquito Twin-Tail |
Rotor Dia. 360 mm | 130 grams | 20 mins | 4 Channel | 22 Jul 2004 |
| Mosquito |
Rotor Dia. 360 mm | 110 grams | 30 mins | 3 Channel | 1 Feb 2003 |
| Microflyer |
Rotor Dia. 128 mm | 7.8 grams | 10 mins | 3 Channel ; uses 2 | 10 Nov 2003 |
| Nanoflyer [] |
Rotor Dia. 85 mm | 2.7 grams | 10 mins | 2 Channel IR | 4 Sep 2004 |
| Picoflyer |
Rotor Dia. 60 mm | 3.3 grams | 1 min | 3 Channel | 7 Aug 2005 |
Commercial products
The helicopters shown above are one-off prototypes built by Petter Muren. None of these helicopters are for sale, however, the Proxflyer rotor system is licensed to Interactive Toy Concepts. The company’s R/C helicopters, which include Bladerunner and Micro Mosquito, are all based on the Proxflyer rotor design. The Bladerunner is considered by some to be the first successful indoor R/C helicopter. Up until the beginning of 2007, the total number of toy helicopters produced using the Proxflyer rotor system is estimated to be about one million. Helicopters utilizing the Proxflyer rotor system are also used in some science projects around the world.See also
- Radio-controlled helicopterRadio-controlled helicopterRadio-controlled helicopters are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training...
- Interactive Toy Concepts Micro MosquitoInteractive Toy Concepts Micro MosquitoThe Interactive Toy Concepts Micro Mosquito is an indoor-only, radio-controlled toy helicopter designed by Interactive Toy Concepts of Toronto, Ontario, Canada. The toy was sold in the United States by RadioShack and in Canada by The Source by Circuit City...
- Picoo ZPicoo ZThe Picoo Z is a miniature remote-controlled 2-channel helicopter manufactured by Hong Kong-based Silverlit Toys...
External links
- Proxflyer official site
- Interactive Toy Concepts official site