UltraFan,

[probes]

with a gearbox and composite fan.
Not actually flying yet, though. But they hope.

[Boac]

Slightly confused on this - RR seem to be making a big issue about the 'gearbox'. For a long time turboprops have used a gearbox to drive the propellor. Is there something radically different in this concept? OK, it is a 'fan' and not a 'propellor', but.........?

[TheGreenGoblin]

The gearbox is designed to support a much wider diameter and lighter composite fan with a high speed turbine (replacing the old slower turbine)...

If I sound like I know about this gearbox, I don't really as I have just read all that here...

Rolls-Royce today announced that it has set a new record for the world’s most powerful aerospace gearbox, just months after testing began. Speaking at the International Society for Air Breathing Engines (ISABE) conference in Manchester, UK, Paul Stein, Chief Technology Officer at Rolls-Royce, confirmed that the Power Gearbox had successfully reached 70,000 horsepower while on test at Rolls-Royce’s dedicated facility in Dahlewitz, Germany. The Power Gearbox will play a central role in the company’s next-generation UltraFan® engine, helping to deliver improved efficiency over a wide range of thrusts.

Testing of the first demonstrator gearbox began on a specifically designed rig in May and having proven that the Power Gearbox is capable of managing the equivalent power of around 400 family cars at full throttle, testing will now focus on lower power functions such as endurance and reliability.

Rolls-Royce’s Power Gearbox is designed to run all the way up to 100,000 horsepower and future demonstrators are expected to achieve these levels. When running at maximum power, each pair of teeth on the gearbox will transmit more power than an entire grid of Formula 1 cars between them.

The Power Gearbox has a planetary design, with each ‘planet’ capable of holding the force of a Trent XWB engine at full throttle. It is designed to allow the shafts at the core of the engine to run at very high speeds while allowing the fan at the front of the engine to run at a slower speed. The associated improvement in efficiency and reduction in weight will allow the UltraFan engine to offer a 25% fuel efficiency improvement over the first generation of Rolls-Royce Trent engines.

https://www.rolls-royce.com/media/press ... arbox.aspx

RollsRoyce.JPG (91.87 KiB) Viewed 285 times

https://www.theengineer.co.uk/rolls-roy ... n-gearbox/

[TheGreenGoblin]

This is all rather interesting...

After the Advance comes the UltraFan, which could be ready for service from 2025, a geared turbofan with a variable pitch fan system, promising at least 25% improvement in fuel burn, The geared/variable pitch UltraFan aims for a 15:1 bypass ratio and 70:1 overall pressure ratio.

The Ultrafan keeps the Advance core, but also contains a geared turbofan architecture with variable-pitch fan blades. As the fan will vary pitch to be optimised for each flight phase, it won't need a thrust reverser. Rolls-Royce will use carbon composite fan blades instead of its usual hollow titanium blades, and along with new material adoption will save 750 lb (340 kg) per engine.

The variable pitch fan will facilitate low pressure ratio fan operability. Rolls-Royce will work with Industria de Turbo Propulsores to test IP turbine technologies that will go into the UltraFan. In Dahlewitz near Berlin, Rolls-Royce has built a power rig simulating loading conditions in flight, sized for 15–80 MW (20,000–107,000 hp) gear systems; and recruits 200 engineers. The ratio of the initial test gear will approach 4:1 and thrust could be up to 100,000 lbf (440 kN).

Ultra Fan

[ian16th]

What is different that RR are doing, from P&W's geared fan? Which seems to be causing them trouble.

Please answer with short words, remember I was a Fairy.

[TheGreenGoblin]

Slightly confused on this - RR seem to be making a big issue about the 'gearbox'. For a long time turboprops have used a gearbox to drive the propellor. Is there something radically different in this concept? OK, it is a 'fan' and not a 'propellor', but.........?

Garret have been using gearing in turbo fans (as opposed to turbo props) for many years vide. the Garrett TFE731 used on corporate aircraft.

[TheGreenGoblin]

What is different that RR are doing, from P&W's geared fan? Which seems to be causing them trouble.

Please answer with short words, remember I was a Fairy.

Pratt and Whitney are asking the same question...

P&W claims of patent infringement

A common technology between the R-R and P&W offerings for the NMA -- a reduction gear in the power system -- sets up a potential clash over intellectual property rights.

"If they do try to sell a geared architecture to Boeing we problably will enforce our rights as we should -- and I'm sure they'd do the same," Leduc says.

The R-R UltraFan features a power gearbox that decouples the rotation speed of the fan and the low-pressure turbine, allowing each module to spin at the most efficient speed. P&W uses the same architecture in the geared turbofan engine, which is offered today on the Airbus A320neo family and four other aircraft families.
Although similar, there still could be major differences. R-R has declined to describe whether the UltraFan's power gearbox employs a star or planetary gear architecture. However, R-R and Liebherr announce a joint venture in 2015 to develop the power gearbox partly at Biberach an der Riss, which is a Liebherr site that specialises in planetary gears. By contrast, P&W uses a star gear design in the geared turbofan engines now in service.

Looks like a planetary gearbox arrangement on the Rolls Royce design to me!

[Boac]

"What is different that RR are doing, from P&W's geared fan?" ian - I suspect the difference is that it is RR

That may be a touch unfair (tee-hee) but the whole thing was not exactly well-explained by the dashed good-looking chap in the promotional video.

[TheGreenGoblin]

What an excellent topic. Should really be on the Engineering/Technical Discussions thread but I suppose the Admin might move it there.

More on what a geared turbo fan is...

For those that are truly nerdy (like me) and get a kick out of this sort of thing there is this Rolls Royce Ultrafan application for Android phones and tablets...

https://play.google.com/store/apps/deta ... r&hl=en_GB