Thursday, 24 July 2014
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Wingless aircraft could usher in UAVs that enter buildings

A new aircraft that flies without wings or traditional rotors could lead to high-speed unmanned aerial vehicles (UAVs) that are small and accurate enough to enter buildings.

Austrian firm IAT21 has drafted a team of engineers from Cranfield University in a collaborative partnership to help take the company’s prototype vehicle, which was recently unveiled at the Royal Aeronautical Society in London, to the next stage of development.

The craft, named D-Dalus (a play on the Greek mythological character Daedalus) and designed by inventor Meinhard Schwaiger, flies using four barrel-shaped rotor assemblies that, in theory, enable it to fly in any direction at up to 400kph.

IAT21 eventually hopes to create an autonomous vehicle that can fly in any weather through smoke and radiation, hover very close to cliff faces or buildings and even enter them to recover casualties or collect or deliver materials in hazardous situations.

The company says it has so far proven that the prototype D-Dalus, which was on display at last week’s Paris Air Show, can hover 3m above the ground and turn 15–20° around horizontal and vertical axes.

The next step will be to select a larger engine than the 120-horsepower motorcycle engine currently used, in order to power a bigger version of the craft to fly further, faster and in all directions.

d-dalus

D-Dalus is designed to fly in any direction at up to 400kph

Each of the rotor assemblies comprises a set of disks connected by several blades with adjustable angles — forming a structure that looks like a barrel with most of its slats missing.

These rotate at 2,200rpm and can be individually adjusted by a computer system to provide thrust in any direction.

‘The big engineering test is how the hell do you hinge theses blades if they’re going at 2200rpm?’ said Brigadier David Wills, IAT21’s vice-president for defence and leader of the D-Dalus project.

‘We had to find a friction-free bearing and that’s the secret patent at the heart of this. It’s fairly small and it’s mechanical — it’s not got any great magnetic tricks or liquid nitrogen or anything. It’s just three moving parts really.’

The company is using existing engine technology rather than developing its own in order to make it easier to repair in the field and reduce maintenance needs.

The team from Cranfield is helping with engine selection, wind-tunnel testing and preparing the craft for official certification.

Prof Kevin Knowles, head of the university’s aeromechanical systems group, said the concept was similar to several other proposed cyclo-rotor vehicles, but the way the blades were positioned meant that it could change direction differently.

‘By having the axes of the rotors parallel to the direction of flight, the thrust from them can be directed left and right very easily, or up and down, but it can’t be directed forwards and backwards,’ he said.

‘To make it pitch, you have to change the thrust between the forward and rear pairs of rotors, which apparently they can do.’

He said that the main problem for any craft such as this was switching from vertical take-off to forward movement, but Wills said that the design overcame this issue because it could thrust in any direction.

‘It has no concern about flying at any angle so it goes from vertical to horizontal, just from a change of 90° in resultant thrust,’ said Wills.

He added that D-Dalus would take at least five years to develop into a mature technology.

‘This is going to have tons of technological bugs that we haven’t yet predicted, just like the jet engine or hovercraft — which took years to get to maturity from the original idea,’ he said.

IAT21 has submitted proposals for the craft to the British, French and US ministries of defence and spoken to several major firms, including EADS and helicopter manufacturer AgustaWestland.


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