There are some very interesting engine developments in the aerospace sector.
A quick trio…
Rolls Royce Open Rotor
In the 1980’s the open rotor concept was developed that used unducted contra-rotating blades in order to lower fuel consumption. Although flight trials on an MD81 went well, these UnDucted Fans (UDF’s) as they were called, ultimately did not achieve commercial success because of unresolved engineering issues, noise and the main reason, fuel prices stabilised.
Unducted fan engines are very similar to conventional high bypass turbofans, but instead of enclosed rotors they use a higher diameter open rotor without incurring weight penalties with a nacelle.
With rising energy prices and advances in engineering and materials technology the concept is currently being studied again. General Electric, NASA, Snecma and Pratt and Whitney refreshed the concept and started work on newer designs a few years ago under a number of ‘green’ initiatives.
There was a flurry of activity from around 2007 but since then not much has been publicly released. Rolls Royce are confident however, that they can make the design work and have stated it is the future.
As part of the Clean Sky project Rolls Royce is developing the Sustainable and Green Engine (SAGE)
From the project web page
Open rotor technologies offer the potential for significant reductions in fuel burn and CO2 emissions relative to turbofan engines of equivalent thrust. Higher propulsive efficiencies are achieved for turbofans by increasing the bypass ratio through increases in fan diameter but there is a diminishing return to this improvement as nacelle diameters and consequently weight and drag increase. Open rotor engines remove this limitation by operating the propeller blades without a surrounding nacelle, thus enabling ultrahigh bypass ratios to be achieved.
It is claimed that as much as a 30% decrease in fuel consumption can be achieved for a given journey although noise problems remain difficult to resolve. NASA concluded that noise remained a significant challenge although a full report into its two year feasibility study will not be published until later this year.
Rolls Royce are bullish about noise reduction though, this, and blade containment are the current focus. They point out that advances in design realisation tools means they are able to test concepts before going to prototypes. The engine in the picture is aimed at a 20,000 to 25,000 lb thrust range, the normal range for the 100-150 passenger narrow body market and that it should be much more efficient than expected new turbofan designs but noisier.
There are also a diverse range of other concepts and technologies being directed at reducing emissions and fuel consumption so who knows where it will end up.
Airbus have even patented a design for an aircraft equipped with one, click here to read, and even EasyJet are getting into the concept with their EcoJet, although it all seems to have gone quiet on that front..
The designers that formed the core team on the cancelled 1980’s BAE HOTOL project that used the Rolls Royce RB545 eventually went on to create Reaction Engines Ltd.
Reaction Engines are working on the Sabre Engine and the hypersonic unmanned Skylon Spaceplane.
Here is what Lord Drayson had to say
This is an example of a British company developing world beating technology with exciting consequences for the future of space. It is fantastic that Reaction Engines, the British National Space Centre and ESA have successfully secured this public-private partnership arrangement and I look forward to seeing how the project progresses
In April this year the BBC reported a successful first stage pre-cooler test
It will be interesting to see if funding continues and we can grasp this opportunity. It certainly holds the promise of low cost orbital transport, able to lift 12 tonnes into orbit.
Heavy Fuel UAV Engine
Perhaps not as glamorous as the first two the ability to use diesel engines in UAV’s is no less important. High octane petrol has been traditionally used for small UAV piston engines but its transport and storage presents many problems in a military context.
The Wolverine 3 engine was developed by Ricardo specifically for UAV’s and uses JP-8 fuel.
Since its first launch it has been developed further and is now available in a number of variants up to 55hp.
It doesn’t look like much but its impact on the operation of small UAV’s, especially in naval applications, will be immense.