This was called turbo-compounding, a very different thing from straight
supercharging, or straight turbocharging, the main benefit here being fuel
efficiency.
Not quite sure what that 33% figure actually refers to - it could mean
anything - and probably does!

More weight and complexity involved here, but they did in fact improve
specific consumption considerably and over a transatlantic flight, easily
paid that back in fuel load. The advent of the gas turbine soon put a stop
to any further developments in that sphere, the 3340 being about the
ultimate aero piston engine development, though a Super Connie arriving at
Heathrow in that era would rarely be fit for a quick turnaround, with oil
dripping from most of its engines, if not requiring a new parts. In
contrast, Bristol Hercules and Centaurus sleeve-valve radials would run
quite happily for 3,000 hours between overhauls - quite unheard of
elsewhere. I think those big US radials might have reached 2000 hours in
theory, but had a lot to go wrong with all those hot parts and gearing,
poppet valves etc.
Gas turbines of course soon moved up to the 5 and then 9,000 hours MTBO
(JT8D-9) and today have staggering overhaul intervals, no wonder piston
aero-engines were dropped like a hot brick over just a few years - '.. you
mean some of the bits went up-and-down rather than round and round, crickey,
why they do that then!'

Clive

----- Original Message -----
From: "John Rodgers" <j_rodgers@charter.net>
To: "Clive Smith" <clive.harman-smith@ntlworld.com>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, October 19, 2002 3:41 AM
Subject: Re: Increasing horsepower

> Clive Smith wrote:
> >
>
> > In fact it maybe takes 1000 hp to drive the superchargers!
> >
>
> Yes, it does take a bit of power to driver them. But there is some
> efficiency. The old 3340's on the Willie Victors (Super Connies) had
> three turbine power recovery systems mounted in the the exhaust
> collectors. As I recall there was  a reported 33% power recovery. Thats
> pretty amazing.
>
> John Rodgers
> 88 GL Driver
>