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Old November 17th 06, 04:32 PM posted to rec.aviation.piloting
Brian[_1_]
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Posts: 399
Default Take-off practices and procedures...


Could you elaborate more on your 'no' for the procedure I mentioned?
I'm more interested in why one particular talkoff procedure over
another... This is about increasing my personal understanding more than
it is about simply being told 'what the book says' so to speak.


Sure,


True, But not a very smooth takeoff as you have pitch up, pitch down
and then pitch back up.


Done 'correctly' (again, I'm not 100% sure I'm correct, but the old
timers at my club swear by it), the pitch down after attaining ground
effect is very subtle... I do have to say that it "feels" really
smooth.


It can be done very smoothly but this is normally done by not lifting
off at minimum airspeed (full up elevator) but rather just raising the
nose to about the normal climb attitude. Doing this the aircraft will
lift off at a lower than normal climb speed float in the ground affect
until reaching the normal climb speed and then climb out. You will have
to adjust the elevator as the aircraft accelerates but the attitude
will not change. I often teach this to new students because it is
simple and works really well and you don't have to look at the ASI at
all to do so. Just let the airplane accelerate until you just before
you think it is ready to fly, Pull back to raise the nose of the
aircraft until the top of the spinner is just below the Horizon (will
vary some with different aircraft and pilots) and hold it there. You
can try this by starting out with full elevator and as soon a the
attitude reaches your nomal climb attitude hold it there. This is often
done on gravel runways to raise the propeller as high off the ground as
possible. This disadvantage to this technique is that the high angle of
attack while still on the ground extends the ground run due to the
extra drag caused by the high angle of attack.


False in most cases on a paved runway, In fact I watched a Commache
Crash doing this. Fully loaded he was off the ground in 1500 feet in
ground affect nose high. He flew off the end of the 5000 foot runway
still nose high and only 4 feet off the ground before he aborted the
take off. He never was able to reach his best climb speed in the nose
high, high drag configuration.


Hmm... that's interesting, my initial sophomoric instinct suggests that
perhaps he didn't release enough of the back-pressure to accelerate
enough... but as I said - purely sophomoric judgement there.


The biggest issue he had was he was using a modified soft feild
technique when he should have been using a short field technique due to
the high DA and Gross weight. I suspect he always took off this way
and in a 250HP high performance aircraft it didn't occur to him that he
should have been using a short feild. It did not occur to him to lower
the nose because doing so in this situation would have caused him to
settle back onto the runway.



True, But good crosswind rudder and aileron control input will usually
let you take off without having to do so. (Raise the downwind wing and
keep straight with the rudder)


A slip is still a slip though, isn't it? even if you're correctly
downwind-wing-high and on your upwind gear, the wind is still striking
the fuselage at an angle.


Yes it is a slip, but having a little extra speed after lift off will
prevent you from settling back on the runway and it is better to be
aligned with the runway if you do settle back onto the runway. Once a
positive rate of climb is established then release the rudder pressure
to a normal climb setting and let the aircraft Crab into the wind for
maximum climb rate or angle.


-----

Perhaps I didn't respond correctly to your 1st post. It just got my
attention because I have seen an accident caused by this technique. But
the accident was probably caused more by the fact that this was not the
technique to use in that situation. You were asking more about Normal
Take off's and landing. The technique your instructor recommends will
work just fine for normal takes-offs. Here are my points on it
remembering these are normal takes offs.
1 Plus, Helps protect the Prop from Debris.
2. Minus, Longer take off roll due to high angle of attack while
stilling rolling
3. Minus, Slight less control lifting off at minimum flying speed, some
chance of settling back onto runway.
4, Slight Plus, Less wear and tear on tires and struts (minimual
difference in my opinion)

Hope this helps

Brian
CFIIG/ASEL