Bristol Mercury and Pegasus engines

[PMN1]

Would it have been possible to 'double row' these so making them 18-cylinder engines and if so how quickly could it have been done had sleeve valves continued to cause problems?

Its just that I have never read of any consideration of doing this so either it wasn't possible or I havn't read enough....

:)

[Nick Sumner]

I could be wrong but wasn't the Hercules basically a double Mercury? Same bore and stroke but not sleeve valve.

[PMN1]

Janes and other sources show the Mercury and Hercules having same cylinder size and the Pegasus and Centaurus as having the same cylinder size so how quickly could the Pegasus and Mercury be 'double-rowed' to give Cantaurus and Hercules power should the decison to abandon sleeve valves have been made.

[ChrisMcD]

Try this for a short summary

You have to follow the Bristol logic.

Start with the Jupiter - first proper radial in the world - but big, single row, poppet valve and long stroke.

The Mercury is the 'fighter' version, shorter stroke (less cross section) but same power from higher rpm/reduction gearing: http://en.wikipedia.org/wiki/Bristol_Mercury

The Pegasus is the Jupiter with the same upgrades.

Then Harry Ricardo persuades Roy Fedden at Bristol that a 'hyper' engine has go be a sleeve valve

http://en.wikipedia.org/wiki/Harry_Ricardo

So the sleeve valve Mercury becomes the Aquila and the sleeve/Jupiter became the Perseus.

Then Bristol realised that they needed more power so they doubled up the rows - so the single row Aquila become the two row Taurus and the Perseus become the Hercules.

http://en.wikipedia.org/wiki/Bristol_Taurus

http://en.wikipedia.org/wiki/Bristol_Hercules

Then the Hercules leads to the Centarus by reverting back to the original Jupiter stroke!

en.wikipedia.org/wiki/Bristol_Centaurus

I also think that some extra cylinders got squeezed in at some stage since the Centarus is an 18 cylinder engine!

Pity it took them so long