The notorious Centaurus

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7 years 11 months

Posts: 16

Hello nennrita, well, the thread starter is still around and waiting for further insights ... :eagerness: ... but fifteen years is a long time. It's amazing that you found the thread!

It turned up on Facebook about a week ago and having worked on Both engines I was curious, signed up and the rest is history.

Member for

7 years 11 months

Posts: 16

In my post of two days ago the other reason was power. Instead of relying on Memory I refreshed it by looking at Engine powere specs.

a R3350-30W (Military engine) could produce 3700 BHP Wet 3500 dry

Centaurus the highest spec engine about 3000 BHP.

So the wright Turbo compound was the winner in Power stakes.

It was nice to see that my remark the 100 U oil was a necessity being endorsed and that the Sleeve valve engines are/were a magnificent piece of engineering.

Just a small aside and bit of trivia. the Sleeve valve engines parts have a Part number beginning with FB translated Fedden Bristol

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11 years 10 months

Posts: 1,356

Fedden Butler = FB. Fedden was the celebrity chef while Butler cut the onions, but the coding acknowledges it was a team effort. I wonder what the power to weight ratio is between 3350 and Centaurus?

Member for

7 years 11 months

Posts: 16

The Centaurus had a weight of 3400 Lbs and up to 2940 HP wet giving Lbs /hp of 1.156 to 1.19

The R1830 weighed 2670 lbs and between 3350 Dry to 3700hp Wet. Using 3700 HP the lbs/hp is .72.
More grunt for the Lb.

Member for

7 years 11 months

Posts: 16

Fedden Butler = FB. Fedden was the celebrity chef while Butler cut the onions, but the coding acknowledges it was a team effort. I wonder what the power to weight ratio is between 3350 and Centaurus?

Thanks for the correction.

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14 years 8 months

Posts: 2,536

What does wet and dry mean? I've only ever heard that expression used for jets. Burners on or off.

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14 years 3 months

Posts: 194

Water/methanol injection, normally used for hot & high airfield take offs.
Keith

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20 years 2 months

Posts: 278

Does someone knows what was so specific about that 100U oil?

Member for

10 years 1 month

Posts: 4

I have a suggestion to put forward for debate why Centaurus engines may be prone to more failures in modern times. Could this be because of the (relatively) low lead fuel (100 LL) used today? Originally, the Centaurus was specified to use 140 LL for its high anti-knock properties, due to high boost pressures, but because of environmental concerns together with the obsolescence of high boost piston engines (and the use of catalytic convertors (CC) in automobiles), the Tetraethyl lead (TEL) additive was ceased in automobile use and reduced in aviation fuel where there is still a strong demand for a high quality fuel but for relatively low performance engines. So - it is now only available to piston engine aeroplanes as 100LL. Of course there are other differences between aviation fuel and automobile fuel, but this is the one that specifically interests me.

Has anyone involved in the industry considered that this change of fuel from 140LL to 100LL may have something to do with the engine failures? The Royal Navy Historic Flight 'solved' the problem by simply reducing the boost pressure as TEL is used as an anti-knock additive, supported by Rolls Royce (who have not designed an aero engine for nearly three generations of engineers). However TEL has a very important additional property and that is in lubrication (the lead content) especially in sleeve valve engines where cylinder liners are susceptible to failure in marginal lubrication conditions.

An effective solution may be to introduce more TEL and as specified in the formulation of 140 LL and do away with the boost pressure limitations. It is to be understood also that the higher the boost the more spread the TEL or lead becomes in the cylinder liners and the greater the supporting lubrication may become, so reducing the boost may be a grave mistake on two counts. I am a piston engine designer at least in the long distant past and have some experience of marginally lubricated racing car engines, and wonder whether the search for alternative culprits may be a red herring. All engines are prone to failure if badly maintained and there is no substitute for skill and experience, but that is also sadly lacking in supercharged engines especially sleeve valve units, so yes, a contributory element no doubt. In addition the special oil is no longer manufactured, the last batch being destroyed in the huge fire at the Shell Buncefield site in 2005.

Over to people with more knowledge on fuels.....

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18 years 8 months

Posts: 554

Piston engine fuels, top end, 100-130 (green) and 115 -145 (red).
FEAF carried out trials using 100U oil on a couple of Beverleys at Seletar circa 1963 in place of OM270. Then reverted back to OM270. Reasons I know not.
With the introduction of 100LL it was anticipated in the Historic a/c world there would be problems but I do not believe they manifested themselves as max TO power or max cruise was very rarely used.
My personal opinion is that overhaul and maintenance knowledge has diminished over the years and the fact that the correct inhibiting procedures are not followed when aircraft are inactive.

Member for

10 years 1 month

Posts: 4

Once further thought that seems to support the fuel lubrication idea. 'Liners pinching after shutting the throttle' - maybe there was not enough burnt fuel and thus no TEL being forced between the liner and the cylinder wall - or a critically reduced amount to help lubricate the sleeves...... my late father crash-landed a Beaufighter (yes a Hercules, not a Centaurus - after an engine failure following an attacking dive; maybe no relevance, but he survived and with the assistance of my mother produced me - for better or worse! The energy enabled him to climb on one engine enough to sort out a kind-of landing.

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11 years 8 months

Posts: 34

Wait, since the topic started with the question of Furys having their engines swapped with US units, why are compounded versions of 3350 being mentioned here for comparisons anyway? They had their own reliability issues and nobody uses them in air-racing, as there are other methods of increasing performance for racing purposes. Neither "Rare Bear" nor "September Fury" use compounded Cyclones.

Unless we're just talking generally about 3350 vs Centaurus, then yes, any version can be discussed.

In either case, I'm fairly sure the swaps were done mostly because of spare parts availability. Neither parts nor qualified workforce for maintaining modified 3350 are simple to find in US these days and I can only imagine they're almost nonexistent for much less popular British units.

Member for

7 years 11 months

Posts: 16

Water/methanol injection, normally used for hot & high airfield take offs.
Keith

Also used to delay/prevent detonation to obtain additional HP for take off. Not necessarily only for hot and dry airfields.

I know that with the R3350s 70 " MAP with water Methanol , 60"MAP without. We always used 70" for takeoff.

Member for

7 years 11 months

Posts: 16

Wait, since the topic started with the question of Furys having their engines swapped with US units, why are compounded versions of 3350 being mentioned here for comparisons anyway? They had their own reliability issues and nobody uses them in air-racing, as there are other methods of increasing performance for racing purposes. Neither "Rare Bear" nor "September Fury" use compounded Cyclones.

Unless we're just talking generally about 3350 vs Centaurus, then yes, any version can be discussed.

In either case, I'm fairly sure the swaps were done mostly because of spare parts availability. Neither parts nor qualified workforce for maintaining modified 3350 are simple to find in US these days and I can only imagine they're almost nonexistent for much less popular British units.


Topic started with why the Sea Fury's Centaurus were swapped with Wright R3350 turbo compound, Not US Radials in General.

Member for

7 years 11 months

Posts: 16

Does someone knows what was so specific about that 100U oil?

I THINK the formulation of the oil was to withstand high temperatures and small tolerances between sleeve and cylinder wall and to prevent Oil breakdown between Sleeve and Cylinder wall increasing friction thus causing increased wear and tear, due to high temps.

Member for

7 years 11 months

Posts: 16

Piston engine fuels, top end, 100-130 (green) and 115 -145 (red).
FEAF carried out trials using 100U oil on a couple of Beverleys at Seletar circa 1963 in place of OM270. Then reverted back to OM270. Reasons I know not.
With the introduction of 100LL it was anticipated in the Historic a/c world there would be problems but I do not believe they manifested themselves as max TO power or max cruise was very rarely used.
My personal opinion is that overhaul and maintenance knowledge has diminished over the years and the fact that the correct inhibiting procedures are not followed when aircraft are inactive.

OM270 is a heavier viscosity oil the 100, so it may be because of the higher ambient ground temps in the tropics.

At Richmond Australia , 1960s, we were using 100 U for both Hastings (weekly Courier service) and Beverleys (occasionally).
We had to re-oil using Hand pumps from 44 Gallon Drums and always at night.

Member for

11 years 1 month

Posts: 28

The R-2800 seems to be the preferred choice for Sea Furies now, see here: http://www.sandersaeronautics.com/restoration_seafury-r2800.asp

115/145 avgas is still available from VP Racing Fuels in the US.

With respect to the oil issue there is some potentially good news on the horizon in that the Swift Fuels 102 octane unleaded fuel looks like it will become a reality (fingers crossed). This opens up the possiblity of using synthetic oils in aircraft piston engines. https://swiftfuels.com/fuel/ul102-avgas/

Did the Napier Sabre use Aeroshell 100U or was that a post war development?

Member for

7 years 11 months

Posts: 16

INteresting information re a different engine to the conversion,

AS far as to what oil the Napier Sabre used that is for someone else to respond. I was only a Lad in on the other side of the world.
there are different circumstances coming into play as the Sabre is liquid cooled and cylinder wall is at a lower temperature., However 100U was in use in wartime.

Member for

7 years 11 months

Posts: 16

Piston engine fuels, top end, 100-130 (green) and 115 -145 (red).
.

re Fuel Colour In my part of the world Red = 80-87 Green =100-130 and Purple =115 -145
and Clear 80 unleaded.

Member for

18 years 8 months

Posts: 554

re Fuel Colour In my part of the world Red = 80-87 Green =100-130 and Purple =115 -145
and Clear 80 unleaded.

Correct, time dims the memory.