On May 4, 12:12*am, Michael wrote:
Very beginning pilot here (again).....and I am confused about the
appropriate way of holding the stick during the ground roll prior to
take off.

In Thomas Knauff's Glider Basics, he states (p.59, 2005 edition):
"....before signaling to proceed with the launch, the glider pilot
should set the elevator by holding the control stick at the
approximate position that will result in the proper angle of attack.
To do this, move the control stick the full allowable travel fore and
aft, and then find the mid-point, or neutral position. *Move the
control stick back about 1/2 inch from this neutral position. *This
will be very close to the optimum position for takeoff. Aircraft
designers build aircraft this way."

However, in Russell Holtz's Flight Training for Gliders, I see (p. 27,
2008 edition): "If the glider norally rests on its main wheel and tail
wheel, the stick should be held forward of neutral, so the as the
glider picks up speed, the tail wheel will rise off the ground."

I'm training in a Blanik L-23, which has a main wheel and a
tailwheel. * Knauff makes no mention of whether to hold the stick
forward or aft depending on if the glider has a tail wheel or a nose
wheel, yet Holtz does.

(It's been three weeks since I've flown, and I can't remember what my
instructors did.)

For a glider with a tail wheel, which is correct?

--Michael

Michael,

I wanted to respond to your questions with the reasons that I advocate
the takeoff technique described in the Flight Training Manual for
Gliders.

I recommend getting the glider balanced on the main wheel as soon as
possible. You can see why this is important if you look at what can
happen if you keep either the tail wheel or the nose wheel on the
ground too long.

In a tail dragger, if you hold too much back pressure (or the elevator
is trimmed too far back) the glider will lift off while the tail is
still being “pushed” into the ground by the elevator. The glider can
then lift it’s main wheel off of the ground, but keep increasing it’s
angle of attack because the excess back pressure keeps the tail wheel
on the ground. The glider can either stall, or more likely, lurch
into the air and climb rapidly. This could pull the tail of the tow
plane up, driving it’s nose into the ground. Or, as the glider lifts
off rapidly, the pilot/student will often over control, causing the
glider to slam back down to the ground, possibly starting a pilot
induced oscillation.

With a nose dragger, if you hold too much forward pressure (or the
elevator is trimmed too far forward), the glider can reach flying
speed, yet still not be flying because the angle of attack is too low
to generate sufficient lift. If the stick is then moved back to lift
the nose, the glider can lurch into the air quickly, causing the same
problems just described.

And finally, look what could happen if the glider hits a bump while
rolling on the nose or tail wheels, as opposed to what happens if it
hits a bump while balanced on the main wheel. A bump to the tail
wheel can damage it, or drive the nose into the ground. A bump to the
nose wheel can cause a rapid increase in angle of attack which, if
sufficient speed has been reached, can cause the glider to lurch into
the air, or if flying speed has not been reached, the glider can slam
onto the tail wheel, damaging it or the rear fuselage. If you hit a
bump while balancing on the main wheel, the force will act very near
the center of gravity, and will not cause a change to the pitch or
angle of attack.

So, whether you are flying a tail dragger or a nose dragger, the goal
should be to get the glider in to a flying attitude as soon as
possible. To achieve this, during the initial roll on take off, make
sure the stick is held well forward in a tail dragger, or well aft in
a nose dragger.

I hope this helps to clear things up.

Russell Holtz