Message text written by Graham Singleton
>And why 'some' Europa pilots fly along the runway in ground effect until
>they reach 70 knots, do a rapid (1300fpm solo on a 912) flaps down
>ascent at that speed to 300 feet with their CS prop in takeoff mode....
>and then continue the climb, flaps up, from that point.<
Once airborne speed is more important than height until a safe climb speed
has been achieved. Ground effect reduces drag and helps markedly when
performance is marginal. We used to bear this in mind with the C-130 in the
South Atlantic when over a period of several years we carried out
overweight take-offs assuming no engine failure. Fortunately no one ever
had an engine failure on take-off in this situation but a combination of
flying in ground effect and rapid fuel dumping might just have been crucial
if it had happened. Bear in mind that ground effect is generally limited to
about half wingspan above the ground so the ground had better be flat and
the pilot skills up to the mark (certainly no more than 20ft in the case of
the Europa).
Message text written by Graham Singleton
>Once or twice, in Europas with the Mac trim switch on top of the stick, I
have taken off with the trim accidentally disturbed to nose up. Getting
clumsy with a clipboard perhaps. This also happens , on some but not all
Europas, if you perform a go round with the trim set for a glide approach.
I don't know what is the critical feature that causes this trim change with
power. Any ideas from aerodymix whizzards would be worth hearing.
The point of this waffle is that you have to push hard on the stick to keep
the speed safe. I think this scenario was the last straw involved in my
camel's demise.<
Go-arounds from the approach configuration involve significant trim changes
with many aircraft types. This is a case where flying pitch attitudes is
particularly important. Set the attitude and power, check the speed and
trim out the pitch forces. Do not consider flap or flap/gear retraction
(trigear or monowheel as appropriate) until terrain clearance is assured.
This also applies in a reverse sense with power loss/failure on initial
climb out. Immediately push to the glide attitude, check the speed and
trim out the pitch forces. Apart from preventing speed decay the push will
unload the wing preventing a stall. Although pushing to zero 'g' might be a
little excessive remember that an aircraft cannot stall at zero 'g' so by
pushing the stall speed will automatically fall below the present speed,
more than compensating for any differences between the power on and off
stall speeds.
Although stall practice at altitude is to be commended, practicing avoiding
the stall by simulating the above at altitude is even more valuable. A good
stall recovery might just save the day at a few hundred feet (if you are
lucky) but proficient flying skills in marginal take-off conditions and
during power loss/failure near the ground is every bit as important.
Unfortunately the benefits of ground effect cannot be simulated at
altitude.
Take-offs in marginal conditions need careful consideration. To avoid
putting myself inadvertantly into this situation I intend to use the
following procedure whenever the performance looks at all limiting:
1. Ascertain the take-off run and distance figures for my aircraft in a
standard set of conditions in advance.
2. Use a spreadsheet to apply performance corrections for differing
parameters (as per the CAA performance leaflet) to obtain revised take-off
runs and distances.
3. Check these against that available at the field in question.
4. If marginal consider changing the conditions to improve performance (eg.
reduce weight, use a more into wind runway, wait for the temperature to
drop etc)
5. If performance is still limiting do the following:
a. Pace out the take-off run and place markers at 1/4 and 1/2 distance.
b. Do a thorough power check and check RPM, T's & P's at the start of
the take-off run.
c. Check the speed at the 1/4 and 1/2 distances. For a Europa they
should be an absolute minimum of 25kt and 35kt respectively. If in doubt
stop.
6. Once airborne use Tony's technique above provided terrain clearance is
assured.
If anyone is interested I have the spreadsheet available to ease the
calculations.
If I have missed any important points please tell me as we all need to
share our experience.
Regards
Nigel Charles
Nigel Charles
|