Ice Detection

Ice build up can cause significant problems with aircraft operations and one of the significant challenges with small and medium sized unmanned aircraft is ice detection.

GKN Aerospace have been leading a nine company research project funded by the EU to move away from traditional methods and use optical detectors.

The programme is called ‘On Wings’ or  ON-Wing Ice DetectioN and MonitorinG System.

Background from the On Wings website

When an aircraft flies in cold, moist air, especially at low altitudes, ice can form rapidly, both on and behind the leading edge of aerofoils and other structures. The growth of the ice disturbs the local airflow and can radically alter the lift of the aerofoil and hence the handling characteristics of the aircraft. This phenomenon has caused a number of fatal accidents and loss-of-control events, and is a problem that will intensify as increased pressures on airports mean that aircraft will spend much longer in low-altitude holding patterns. Large aircraft use hot gases diverted from the engines to remove ice from flight-critical surfaces, while smaller aircraft sometimes use pneumatic ‘boots’ which expand under pressure to shed the ice layers. These technologies are incompatible with future generations of air transport, in which composite materials will be used extensively. Furthermore, current ice detectors are insensitive, cannot distinguish between ice types and are not co-located with the safety critical zones. Building on electro-thermal de-icing technology now widely used in helicopters, the ON-WINGS project will develop a smart, autonomous, composite electro-thermal de-icing system for fixed-wing, helicopter rotor blade and engine inlet applications.

The traditional methods of hot gas and pneumatic de-icing are not well suited to composite structures so the On Wing sensor aims to demonstrate compatibility with composites.

Using fibre optics embedded inside the sensor it measures reflected light, the return signal being analogous to the type, density and thickness of the ice. This information can then be used to cue electro thermal de-icing systems.

On Wings ICE Detection
On Wings ICE Detection
On Wings ICE Sensor
On Wings ICE Sensor

In addition to GKN, the other partners are;

Commenting on the recent trials on an Agusta Westland helicopter, Rich Oldfield, Technical Director, GKN Aerospace said

The ON-WINGS project results have huge potential across aviation. Improving the efficiency of ice protection will have positive consequences for operators of all types of aircraft. More efficient, controlled ice protection will lower fuel consumption, increase airframe or aero-engine performance and endurance and lower maintenance needs – as well as reducing critical carbon emissions. All these are vital factors for operators and users of aircraft worldwide.

Clever stuff eh, another British defence company blazing a trail at the leading edge (see what I did there!)

 

 

 

 

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Chris
Chris
July 18, 2013 8:00 pm

Hmmm. It says here “used to cue electro thermal de-icing systems” which reminded me of a conversation once overheard:

In the late 80s I spent best part of a year on-site at East Midlands Airport working on the installation of a 737-300 full-flight simulator. East Midlands Airport was also the home airfield of British Midland, their head office being just the other side of Donnington racing circuit. The overheard conversation was between two BM pilots on a conversion course to Shorts S360 (otherwise known as Shorts Shoebox) – one said to the other “I read the section in the Flight Manual on icing conditions. It says ‘If icing conditions prevail, keep all the control surfaces constantly moving’…” It seems there was no anti-ice system; the only way to prevent surfaces freezing solid was to keep wobbling them about a bit. How reassuring.

Observer
Observer
July 18, 2013 9:04 pm

Chris, think that was pretty common then. Isn’t as bad as it sounds apparently, once a crack forms along an ice sheet, the wind tends to tear the whole sheet away, so all the ice gets removed at once, even if there was a fair sized buildup.

Can’t remember where I heard it from though.

Mark
Mark
July 18, 2013 10:28 pm

Interesting tech any advance in this area is to be welcomed only a few years ago a dash 8 went in as a result of ice build up with all onboard killed.

As LE, nose cowls ect are areas likely to experience a high probability of impact damage it will be interesting to see how the sensor works following a bird strike event as TAI currently can require a lot of maintainence.

Another Tom
Another Tom
July 19, 2013 6:35 pm

Hi Chris,

There are a few types of ice protection systems that can be fitted to aircraft. GKN use electrothermal heater mats which can either de-ice the protected areas or keep the protected area above 0 Deg C to prevent ice forming in the first place. This is based on technology first used by D Napier & Son post war and have been used on aircraft ranging from the Gannet and Viscount through Concorde right up to the Boeing 787. Military use includes Tornado engine inlet, V-22 engine inlet and the EH101 main and tail rotors. Electrothermal is one of the most energy efficient IPS.

There’s also electromechanical systems which work by suddenly flexing the protected surface to break any ice that has accreted. Theses systems haven’t gained wide spread acceptance yet (partly because they tend to go off with a loud bang when in operation!).

An old technology is pneumatic boots. These are rubber boots which are pumped up with air to break any ice that has accreted. These use less energy, but are not reliable and spoil the aerofoil shape. These are commonly found on light transport aircraft such as the Dash-8.

Finally (before I bore you all too much!) there’s bleeding hot air off the engine and ducting it along the wing leading edges to either de-ice or anti-ice the wing. These types of systems are used on pretty much every large transport aircraft (and also aircraft like the Nimrod). This is proven technology, but requires more energy than electrothermal.

It should be remembered that not all aircraft have IPS fitted, hence your story about the Short.