AIRCRAFT OPERATING INSTRUCTIONS – VIRUS 912 S-LSA GLIDER
Page
38
This is flat wrong! The wing structure in light planes is usually certified to take +3.8 G’s, -1.52 G’s (plus a
certain safety factor). Put more load on the wing than that and you can lose a wing. But here is the nice
part: below a certain speed, the wing simply cannot put out a full 3.8 G’s of lift! It will stall first! This
speed is called Maneuvering Speed or V
A
. Maneuvering Speed is defined as the maximum speed the
plane can be flying at and still stall before the wing breaks no matter how much you pull back on the
stick. If you are going slower than the V
A
and you pull the stick all the way back, the wing will stall without
braking physically. If you are going faster than the V
A
and you pull the stick all the way back, the wing can
put out so much lift that it can be expected to break. Therefore people think they can deflect the stick as
much as they desire below Maneuvering Speed and stay alive. Right? No, wrong! This is a trick question.
The Maneuvering Speed is based on pulling back on the stick, not pushing it forward! Note what was
said above: The V
A
is defined as how fast you can fly and not be able to put out more than 3.8 G’s of lift.
But while the plane is certified for positive 3.8 G’s, it is only certified for a negative G-load of 1.52 G’s! In
other words, you can fail the wing in the negative direction by pushing forward on the stick well below
the V
A
! Few pilots know this.
Also, for airliners, certification basis require that the rudder can be fully deflected below Maneuvering
Speed, but only if the plane is not in a sideslip of any kind! (e.g. crab method of approach) Does this make
sense at all? Why would you need to fully deflect the rudder if not to re-establish wings-level flight?
In a wonderfully-timed accident shortly after Sept. 11th, 2001; which many first thought an act of
terrorism, an Airbus pilot stomped the rudder in wake turbulence while the plane was in a considerable
sideslip. The combined loads of the sideslip and the deflected rudder took the vertical stabilizer to its
critical load. A very simple numerical analysis based on the black box confirmed this. The airplane lost its
vertical stabilizer in flight and you know the rest. Also, if you are at your maximum allowable g-limit (e.g.
3.8) and you deflect the ailerons even slightly, you are actually asking for more lift from one wing than
the allowable limit! Therefore combined elevator and aileron deflections can break the plane, even if the
elevator is positive only!
SO, WHEN YOU THINK THAT YOU CAN DO AS YOU PLEASE WITH THE CONTROLS BELOW MANEUVERING
SPEED, YOU ARE WRONG!
9. AIRCRAFT GROUND HANDLING AND SERVICING
.
9.1 Ground Handling.
Engine start-up
Make sure both fuel valves are open and master switch in OFF position (key full left).Should the
engine be cold, apply choke (lever full back). Set master switch ON (key in full right position). Set
both magneto switches ON. Avionics OFF. Engage engine starter and keep it engaged until the
engine starts. Set throttle to 2500 RPM. Slide the choke lever forward gradually.
CAUTION! When the engine is very cold, the engine may refuse to start. Should this occur, move
the choke handle fully backwards and hold it there for some 20 seconds to make mixture richer.
Engine warm-up procedure
The engine should be warmed-up at 2500 RPM up to the point working temperature is reached.
Warming-up the engine you should:1 Point aircraft’s nose into the wind.2 Verify the engine
temperature ranges within operational limits.
CAUTION!
Avoid engine warm-up at idle throttle as this causes the spark plugs to turn dirty and
the engine to overheat.
