The 1340 Wasp was the first engine from the famed Connecticut
manufacturer, was built in huge numbers—something more than
34,000 engines—and was used on a huge variety of civilian and military airplanes. The gigantic production numbers for the 1340 are
another feature that makes the T- 6 attractive today because, unlike
some less commonly built engines, parts are still readily available.
That helps hold down ownership costs for the T- 6 and keeps you
flying instead of waiting to find replacement parts.
TRANSITIONING TO A RADIAL
Operating the big radial engine is one of the most important parts of
transitioning into a warbird from the flat engines most of us fly. The
new procedures start during preflight where you pull the propeller
through at least nine “blades” to make sure none of the lower cylinders has hydrolocked. Engine oil, or sometimes even fuel, can drain
RUDDER SHAPE MATTERS
Once it settled into high-volume production, the T- 6 series
had few design changes compared to most other warbirds
that were produced in big numbers. But the rudder shape
and size were the target of several design experiments.
The earliest T- 6 models had a rudder with a rounded
trailing edge. During flight testing and development some
spin-recovery issues were discovered. So a new rudder
shape was designed that had a nearly straight trailing
edge and a lower surface that was squared off and
extended downward several inches to get more rudder
surface into undisturbed air to aid in spin recovery.
The new rudder shape worked, but on most models of
the T- 6 used by the Army the tail cone also was lengthened
to give the rudder more authority. On the SNJ models the tail
cone was not stretched, but the rudder has significantly
more area with a squared-off lower edge.
into the lower cylinders and become trapped
there. When the piston rises, the oil cannot
be compressed and something has to give,
usually a connecting rod that gets bent.
Pulling the prop through by hand makes
sure there is no hydrolock.
Another jolt during preflight is the oil
level check—it’s in gallons, not quarts. The
oil tank holds 10. 1 gallons. That’s 40 quarts.
Sean said the R-1340 does not burn or leak
oil at the same high rate as many other radial
engines and normally only goes through a
quart of oil every couple of hours.
When it was designed in the 1930s the
T- 6 was one of the early military airplanes
with retractable landing gear. Prototypes
of the airplane had fixed gear, but the military quickly realized that to prepare pilots
to fly frontline airplanes retractable gear
was necessary.
An engine-driven hydraulic pump muscles the gear and flaps up and down, but it
is a part-time system, what we would call
“open center” in a modern airplane such
as the Citation business jets. What that
means is the system only pressurizes when
you ask it to move the gear or flaps. On
many versions of the T- 6 and SNJ, changing gear or flap position is a two-step
procedure requiring you to engage the
hydraulic system and then move the flap
or gear handle. On later models, such as
the T-6G that Sean and I were flying,
movement of the gear or flap selector also
activates the hydraulic system.
There are no “over center” locks on the
T- 6 landing gear, but there are pins that slide
in behind the top of the main gear strut to
lock it down. A window on each wing root
lets you see the pin position to confirm what
the two green lights are telling you. You
don’t need three in the green because the tail
wheel is always down.
The early versions of the T- 6 had a great, and
unwanted, tendency to depart into a spin after any aggravated stall. North American tried adding slots in the leading
edge of the wing ahead of the ailerons to address the problem, but the results were not satisfactory.
The solution—even though a T- 6 will still spin if the
controls are crossed even a little at the stall—was new
airfoil shapes for the wing, more twist in the wing to
keep the outboard section flying longer into the stall,
and a new, more squared-off wingtip shape.
IN THE COCKPIT
The T- 6 cockpit is roomy, with pretty good
visibility through the birdcage canopy. But
as in most military airplanes, there are no
floorboards or other interior components.
You are surrounded by the inside of the
outside skin. If you drop anything, or
something falls out of your pockets during
maneuvering, digging the lost item out of
the belly of the airplane, or wherever it
ends up, will be a challenge. But finding it
