"George R. Gonzalez" wrote in message
t...

"Cecil Turner" wrote in message
...

Make sure it also covers his work in the Pacific during WWII as a
civilian
tech rep in
front-line units (flight test and profiling P-38s that resulted in
nearly
double
operational range). Provides a bit of balance.

rgds,
KTF

I've always wondered about this..... I first read abot his
range-enhancing
exploits in reader's Digest when I was about 13 yrs old, and it greatly
impressed me at the time.

Since then, I've picked up a few old airplane tech manuals, and at least
in
the B-17, B-29, B-24, P-51 ones I've seen, they ALL have charts in the
back
with all kinds of airspeed-vs-manifold pressure vs rpm vs range curves.
The B-24 manual IIRC even goes to great lengths explaining the right way
to
lean out the engines, and several scary stories about the crews that never
made it back to base because they forgot to go to lean-running mode.

So did the P-38 go out to the pilots without any range vs airspeed vs rpm
vs
mixture charts??

Or did the pilots ignore the charts, or what?

It may have been a combination of both. "You can tell a fighter pilot, but
you can't tell him very much" is an old saying. Proper understanding of
m.p. vs prop rpm vs airpeed vs range might have saved quite a few engines
and pilots' lives.


Methinks the Linberg story is a bit too neat to be totally correct.

I second your apparent reservations on this matter. The idea of improving
range by appropriate engine manipulation was not at all new. Experienced
transport (including airliner) pilots had known prior to the onset of WWII
that the best economy in the use of fuel involved the cruise regimen.

By dint of trial and error, it became obvious to pilots that if while in
cruise, the a/c were trimmed properly (and due attention paid to this during
the flight), then best fuel economy, and hence the best range, was obtained
by using a combination of high manifold pressure, low prop rpm, and a lean
fuel mixture.

For the P-38, the pilot was supposed to use his drop tanks after takeoff and
forming up, and to employ a high enough manifold pressure as to assure a
swift spin-up to max turbosupercharger speed, in combination with low prop
rpm and auto-lean. The Allison featured a so-called "pent-roof" combustion
chamber, which was supposed to allow for both large power production and
efficient combustion with lean mixtures. When nearing the combat arena, the
P-38 pilot was supposed to switch to internal fuel, drop wing tanks, go from
auto-lean to rich mixture and increase prop rpms; given that the manifold
pressure already was high, the turbosupercharger would spin up to max speed
quickly under the circumstances, the pilot would quickly have max power to
utilize, and he would have the speedy acceleration to combat speed he
desired..

Apparently, many P-38 pilots had been operating under the assumption that a
rather different combination of manifold pressure and rpms (i.e., a somewhat
lower m.p. and higher rpm combination) would give them the fuel economy they
desired and yet allow for swift conversion to combat-ready status; however,
in most cases, the manifold pressure used proved to be too low to allow for
a quick spool-up of the turbosuperchargers (at the very time when more power
was needed Right Now), which was the limiting factor in power production,
and at the same time the prop rpms selected led to too many engine rpms
during cruise, damaging to fuel economy. So the pilot would find both that
he'd used a lot of precious fuel before the fight was on, and that too much
time was needed to accelerate to combat speeds.

Conversely, when a P-38 pilot operated at high m.p. and low prop rpm in lean
mixture, the steps he needed to take (auto-rich, increase prop rpms) would
give him the power and acceleration he wanted faster than if he operated his
engines otherwise, and he would also have burned less fuel prior to entering
combat.

As you note, the tables (if available) would have spelled all this out.
Alternatively, practically any transport pilot could have cleared up any
confusion in a few minutes (if a fighter pilot would have deigned to
listen).




Regards,


George