Today’s episode is about a single seat helicopter design being developed in Australia that makes use of a coaxial rotor system.

And who better to talk us through the design than Airbus A380 captain Richard Woodward. That’s right, Richard is not only Manager of Flying Operations and Chief Test Pilot at CoaX Helicopters but also a line Captain with QANTAS flying the A380.

Some back of the napkin calculations show that you could put 13 of the 20′ diameter helicopters side by side under the A380 wings.

The coaxial rotor design uses two main rotors mounted above each other on the one mast. Each rotor spins in the opposite (contra rotating) direction thereby cancelling out the torque created as a result of powered flight.

This also means that no tail rotor is required – less power lost to the tail rotor system, reduced aircraft length, removal of a significant ground handling danger and a delicate, potential aircraft point of failure.

The dual rotors also allow for a reduction in rotor diameter and rotor tip speeds.

Richard had his start in aviation through the Royal Australian Air Force where he flew Hueys and later moved into SAR and then test flying.

In the interview Richard talks about the process the CoaX Helicopter’s team has had to go through to purchase an aircraft design that was created in the 1950s, reverse engineer the original design drawings with the help of remaining airframes and then reconstruct and re-engineer to get a modern and improved commercially viable flying example. He describes the process as ‘eye watering’.

The results speak for themselves with a very fun and compact helicopter – check out the video further down the page.

Some additional interesting things about coaxial rotor systems for those of us not used to them:

* top speed is limited by flapping to equality of the rotors – where one side is high the other is low reducing the clearance between the two discs

* retreating blade stall is not such a factor because of the lower blade tip speeds (smaller diameter)

* reduced blade tip speeds provide a lower noise signature

* top speed is almost practically the same in any direction – tail fins do come into play

* 9 – 17% of engine power is lost to the tail rotor in a conventional helicopter

* yaw control in coaxial rotor designs can be problematic but is overcome in Coax Helicopter’s designs by drag flaps on the end of the rotor blades that provide a torque differential between the blades

* yaw pedal inputs required are small and relatively steady with no tail rotor effects to worry about

* center of gravity is something that needs consideration as much of the weight is close to the mast

* gust response in the hover is reduced as the contra rotating rotors experience opposite effects

Kamov and Sikorsky would seem to be the only other current manufacturers with flying coaxial rotor helicopters.

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In this week’s episode:

01:20 Thanks for sharing the show with your connections

02:00 HAI Heli Expo 2015

03:05 Clean Up Australia Day – with helicopters

04:20 Richard Woodward started flying in 1971 with the RAAF

06:00 Flying Hueys

07:11 Peacekeeping ops in the Sinai

08:40 SAR, instructing and Empire Test Pilot Course

10:40 Early NVG test and development and Papua New Guinea HDA ops

14:40 Blackhawk introduction into Australian service

16:50 Flying 747s, 767, A330 and A380 No.1 in France

18:50 Advantages that helicopter pilots take to jumbos

20:30 CoaX Helicopters and aircraft genesis

22:00 Torpedo carrier and air target towing

22:40 Co-axial rotor design and shafts

24:10 Limitations and advantages, aerodynamics

26:20 Generating yaw control

28:40 Tail rotor absorbs 9-17% of power in a normal helicopter

29:30 Reduction in ground handling danger due no tail rotor

31:00 Noise and engine operation

32:10 Center of gravity considerations

33:40 Scaling the design up and production

36:40 Flying characteristics and manoeuvring

38:00 Licensing and training

42:50 Autorotations

44:30 Helicopter monitoring system fitted as standard

47:40 Reaction of fellow A380 aircrew

49:11 Converting original paper designs into 3D models and engineering

51:30 Looking for investment and purchase orders

52:30 Episode Sponsors trainmorepilots.com

52:55 American Helicopter Museum and Helicopter Museum, UK will be part of World Helicopter Day, 16 Aug 2015

Links from this week’s episode:

CoaX Helicopters

World Helicopter Day

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In the show I talk about a Clean Up Australia Day event I was part of where we used a MD500 to external load out rubbish from mangroves near Redcliffe airfield. Pics below.

Be part of the conversation and get involved in the comments section below. What questions do you have about this one man helicopter or the coax design?