Monday, 21 May 2018

Wilmslow U3A visit to Rolls Royce Derby

A couple of months ago Wilmslow U3A hosted a presentation by Luke Logan,  Chief Engineer for Civil Aerospace at Rolls Royce plc. Today we followed that up with a visit to Rolls Royce at Derby.

Our coach left the Coach and Four (former New Inn) in Wilmslow at 11:00 for a lunchtime arrival in Derby, where Rolls Royce provided us a light sandwich lunch. Over Lunch, Andrew Davies, Deputy Chief  Financial Officer for Civil Aerospace and Finance Director for Civil Operations gave us an overview presentation of Rolls Royce business directions. This was followed by a technology presentation by Mike Whitehead, Engineering Technology Director.

Mike's fascinating talk was on future engine technology, which for as far ahead as one can see will be gas turbine based as no other power source has anything like the power capability for the weight and size of power unit needed in aerospace use. We won't be seeing electric airliners for a very long time yet, if ever. As an example of the level of technology in today's turbofan engines, he mentioned that a single turbine blade in such an engine is smaller than the human thumb, sits in a gas flow where temperatures are similar to the surface of the Sun (many times the melting point of the metal the blade is made of), and extracts from the gas flow more power than a Formula One car develops.

To prevent it melting, the blade is cooled by a cooling system that could keep an ice cube firmly hard frozen in a domestic gas over at gas mark 9.

RR Trent conventional 3-shaft engine. Note how the casing for the low pressure fan turbine at the back of the engine restricts the thrust-producing bypass air flow from the fan.

But the big upcoming development in gas turbine technology is the Ultra Fan. Conventional Rolls Royce engines  are 3-shaft: that is, there are 3 concentric shafts running the length of the engine's centre. The inner one connects the high speed turbine to the high speed section of the compressor, the intermediate one does the same with the intermediate turbine and compressor, and the outer one connects the fan turbine to the thrust fan on the front of the engine. The high speed turbine is a relatively small diameter, and the fan turbine is a large diameter. All 3 shafts can run a speed that produces optimum efficiency, but the last shaft, the one driving the fan, has to run at a compromise speed. Also, its large diameter turbine case causes unwanted constriction to the bypass air duct.

The compromise of the turbine driven fan is that the engine designer wants the turbine to run at as fast a speed as possible for more efficiency and smaller size (less weight and less constricting of the bypass duct. He wants the fan, however to run a slowly as possible so it can be larger to move a bigger volume of air, while remaining subsonic (may be trans sonic) at the tips for best thrust efficiency and quieter running (the buzz-saw whine you hear from a Turbofan engine comes from the shock waves generated as the fan blades go super sonic).

So the Ultra Fan uses a gear box. It does away with the fan turbine and the fan drive shaft, making the engine 2-shaft, not 3. Instead of being driven by its own turbine, the fan is driven through an epicyclic reduction gearbox with a ratio of 3.8 to 1, driven off the intermediate shaft. This gear box has to be around 97% efficient (pretty much unknown for gear boxes up to now) to reduce excess heat generation, it has to transmit up to 100,000 hp, and it has to weigh no more than a ton. Rolls Royce have built a plant in Dahlewitz, Germany, to build and test the gearbox. 

Ultra Fan gear box replaces the LP turbine and fan drive shaft

Some of the challenges faced in developing the gearbox were explained. For instance the gear teeth are accurate to about 3 microns (a human hair is about 75 microns diameter). However, the forces the teeth are transmitting and the centrifugal forces due to the planetary gears' high speed rotation distort the gears by up to 100 microns in use. It might seem obvious that gear oil would be used to lubricate the gear box, but that was found to be to viscous, and also carcinogenic; not good when one considers the gearbox runs so fast that it cannot use conventional seals. Instead, air seals are used which means (since compressed air from the engines is used to pressurise the passenger cabin) minute amounts of this oil may be present in the cabin air.

Instead, the gearbox is lubricated by engine oil, whose main jobs are to prevent metal to metal contact of the gear teeth, and to carry away the heat (the gearbox runs at about 80 degrees Centigrade and must be cooled - not easy if the aeroplane is taking off at perhaps Dubai with a 50 degree ambient air temperature).

A final thought on this remarkable gear box; each pair of teeth transmit more power than an entire Formula One grid of race cars - about 20,000 hp.


We re-boarded our coach for the short trip to the Rolls Royce Trust Heritage Centre, where volunteer guides Tony Ruff and John Plant showed us around.

 Rolls Royce's first commercial 3-shaft engine, the RB 211. Note the straight fan blades with strengthening ring at about half blade span. This engine was originally designed with a carbon fibre composite fan, which proved too fragile (failed bird strike tests). Launch customer Lockheed planned to put it into the L-1011 TriStar, but the failure of the RB 211 bankrupted the Company.

The government rescued Rolls Royce, a titanium fan was developed, and Lockheed got their engines. 

The prototype 3-shaft engine, developed for a Fairchild aircraft that didn't make it to production

A closer view of the straight fan blades and strengthening ring 

A demo RR Merlin engine mounted of a trailer, here showing the control panel 

The next generation of RB 211 engine had wider chord, curved, fan blades and no longer required the strengthening ring. 

Latest fan blade shape, here on the Trent 900 

 The first production Rolls Royce jet engine, the Welland (with a cowled Griffon piston in the background)

One of Rolls' most successful engine, the Dart turboprop. Used on the Viscount, Fokker F27, and HS 748 among many other aircraft, it has a dual centrifugal compressor. 

This isn't a RR engine, it's a de Havilland Ghost engine as fitted to the Comet 1. The Comet 1 suffered some tragic crashes caused by metal fatigue. This was exacerbated by the airframe being built of this aluminium to save weight, as the Ghost engine had insufficient power for an airframe of conventional weight.

The Comet re-appeared as the Comet 4, powered by RR Avon engines. Its problems were behind it, but by then the American Boeing 707 had taken the market.


Saturday, 19 May 2018

Astley Green Colliery Museum Steam day

Brilliant day at Astley Green Colliery Museum Steam Day today. The weather couldn't have been better. We (me & Malc) went on the Little Bikes via Mobberley, Ashley, Dunham, Cadishead, and Culcheth and noted that someone has done us all a favour by burning down the outrageous toll booth (a toll to cross a dried up river bed where the Mersey once flowed) at Warburton bridge. 
We returned home over the Chat Moss dirt roads. Always a bit of a challenge!

Please click on a picture for a larger image.

 Malc admires a steam organ and its showman's engine.

 Till Joseph with his lovely miniature engine.

 Another miniature enjoys the day!

 Till Joseph goes for a bimble around the site

 A gleaming Fowler ploughing engine. One of a pair which would have used the winches beneath their boilers to haul the plough back and forth across the field.

Gardner 6 cylinder diesel engine in this Pickfords tractor 

Another view of the Fowler ploughing engine 

 Malc and Peter Flitcroft with a little Tasker steam tractor, very similar to one Peter is currently having rebuilt.

 The heart of Astley must be this iconic pit head gear. The main pit here was 2,000 feet deep, and in that engine house is a double tandem compound steam winding engine. Back in the day it had SIXTEEN Lancashire boilers feeding it with steam.

Today it will run (briefly and slowly) on compressed air.

The pit head gear is a listed monument, but needs a lot of restoration as corrosion has taken its toll.

 Ian Whitfield with his steam tram was giving rides to visitors.

 Looking towards the entrance from the steps of the winding engine house.

 The crowds gather to watch the running of the giant winding engine on compressed air.

These are the high pressure and low pressure cylinders on one side of the engine (you can just see the LP cylinder of the other pair behind the HP cylinder of the near pair). Each pair of cylinders drives a crank on either side of the winding drum, thus it's a four cylinder engine, double compound, tandem.

On the side of each cylinder is the Corliss valve gear with the long rod between the two cylinders connecting the valve gear on each.

The common piston rod for the HP and LP cylinders is behind that valve rod.

Click here for a video of it running: Engine running on air

As ever, these little bikes can find an unobtrusive parking position just about anywhere


Saturday, 12 May 2018

Ashley Hall Traction Engine Rally, 12th May 2018

I went on the little bike (Honda Innova 125) which is ideal for a day out like this.

Please click on any picture for a larger image.

 The advantage of going on my little bike (125 Honda) is you can park it among the action - just behind the ring-side stalls instead of miles away in the car park

 General view of the engine park just after the show opened.

 Blond on a tractor....

 ...And another! "Three wheels on my wagon...."

 Tractor line-up

 Pop-pop-pop-pop.... It's a single cylinder Field Marshall popping and bobbing its way around the rally arena.

 Vanguard of Lymm, with a rather fine trailer.

 Half-size engine with a father and son crew

 Matthew Jodderz Jodrell proud owner and driver of this rather nice roller 'Britannia'.
I know Matt from the Churnet Valley Railway (1992) PLC where he is steam locomotive crew.

 Matthew Jodderz Jodrell leans out to see what the hold up is getting into the arena.

 Fowler showman's engine

 Another showmans engine in more traditional colours

 'Britannia' in the engine line-up

Engine line up with miniatures in front 

 'Britannia' leaves the arena.

 Matt on he regulator and reverser of 'Britannia

Bike line up 

 A noisy and smoky but very nice Yamaha 125 2 stroke racer.

 The chap on the BSA is well into his '80s!. Must keep you young, this motorcycling lark....

This lady has a whole collection of these rare beasts, apparently


Wednesday, 9 May 2018

Give my regards to Broadway

We've just returned from a few days visiting elder daughter in Broadway in the Cotswolds, a pleasant break we take annually. It's a lovely part of the world; villages of honey-colored stone in the evening sun -  quite stunning. Lots of fabulous pubs serving superb food and ale. And a great heritage railway, too.

We visited the Cotswold Falconry Centre near Burford-on-the-Hill (highly recommended), enjoyed local villages, and of course I had a day on the Gloucester Warwickshire Railway, including their new northern extension to their restoration of the original line, up as far as Broadway itself (the line originally connected Cheltenham to Stratford-on-Avon via Broadway).

Next stop Honeybourne, to the line's original connection to National Rail's main Oxford to Hereford main line?

Please click on any picture for a larger image.

Broadway from Fish Hill 

Chrystal the Snowy Owl at the Cotswold Falconry Centre 

Claire with Desmond 

Vulture sunbathing 

Wet Wednesday morning at Toddington station on the Gloucester Warwickshire Railway. Our loco for the day is 2807, an ex-Great Western 2-8-0 freight engine, which offers scant weather protection for the crew on a day like this. 

Newly-opened halt at Hayles Abbey. This is a replica of the original one at this location.  

The steam train ran from Toddington down to Cheltenham Racecourse via Winchcombe, then back up to Toddington. From there we headed north (above) on the new extension of the line to Broadway

Crossing Broadway Bridge 

A damp member of the footplate crew, with the inadequate tarpaulin between cab and tender which doesn't really keep the rain off 

2807 runs-around the train at Broadway ready for the return journey to Cheltenham. It's carrying an appropriate head board. 

I left the steam train at Toddington (for now!) to have a light lunch before joining the northbound Diesel Multiple Unit (DMU) to have another run up to Broadway 

 The advantage of the DMU is the view out of the front. Here approaching Broadway station.

The recently built station at Broadway is a credit to the railway. It's a close replica of the original station which was closed and demolished on the 1960s, and the quality of the brickwork and canopy is superb. 

Only the 'up' platform is currently in use. The down platform has no shelter as yet, just the immaculate replica Great Western signal box, which has yet to be fitted out and commissioned. The loop points at Broadway are currently operated by ground frames and as yet there are no signals in use.