Glider winching
or "How to give the pilots their monies worth!"
Winching is an important part of the club's operation and it
is vital that we all adopt a standard method of launching in order
to get the maximum from the winch with the minimum amount of wear
and tear on the equipment.
So in an aim to achieve the avove there follows details of the
procedures that should be adopted. Hopefully, we are all using
this method adn this document weill therefore just refresh your
memory. If however, you are not using this method then please
do so and if in doubt please ask.
The method describes a typical K21 launch.
The following also assumes you know the correct procedures regarding
starting the winch, you are familiar with all the controles and
the verious observations alos made during the winching process.
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Up Slack
Once the up slack singnal is observed make sure you select the correct
drum for launching and engage inot gear smoothly and without "gratting".
This is best achieved by applying the transmission brake and moving
the gear select lever to the appropriate side. As you start to feel
some resistance take of the over-run brake. As you release the over-run
brake the tension in the cable pulls the drum round slightly and thus
allowing the winch to "drop" into gear as the cogs line up.
This takes a bit of practice but worth the effort and avaids those exensive
sounding noises as the gearings's teath grind across each other.
There will of course be times when the avove desn't work, so best practice
is to then ease off the transmission brake very slightly to allow the
drive shaft to rotate a small amount whilst applying a gentle amount
of pressure to select the gear. NB emphasis hire is on slighty and gently
again whith practice gear selection should be painless, (for the winch
that is)
Once in gear take up slack slowly and gently with only the minimum
amount of power. Too fast and you run the risk of the glider over-running
the cable with the associated risks. Snatching can also cause damage
to the glider. There should b a definite stop/pause between up-slack
and all-out i.e. once the slack has been taen out of the cable the drum
should be stopped before all-out is actioned.
NB The amount of power equired to take up slack can very depending
on the grass being dry, wit, long frosty etc...... and also what sort
of mod the winch is in. It may be neccessary to keep things under control
during this phase by using the appropriate drum brake - never the transmission
brake.
Do not try to rush the up-slack phase- if it takes a while to wind
the slack so what! It is far more preferable to have people at the launch
point grumble at ethe slack being taken in slowly than to have an over-run.
All Out
Ensure your "free" hand is placed on your knee in readiness
to select the correct drum if and when required.
Apply a small amount of extra power at firs to take out any residule
slack that is usually still prescent in the cable.
Accelerate smoothly and gently to the second stop i.e. full throttle.
DO NOT bang the throttle to this point as thiscauses rapid acceleration,
which is unpleasant and potentially very dangerous for the pilot, *there
has been instances where pilots have been stunned by hitting teir heads
on the canopy frame due to this sudden acceleration. Fortuately they
"came round" before anything else dramatic happerned - be
warned. I find counting to 3 of 4 elephants to full trottle a good guide.
Keep watching the all-out signal untill the glider rotates and can
be observed from the winch, then it should be simple case (providing
the pilot is flying the lauch correctly) of keeping the throttle where
it is untill the top of the launch. However you should still watch the
glider and respond accordingly to his/her commands.
Aim to keep the enging note contant practice will tell yu when this
is ok.
Top Of the Lunch.
You shold have noticed that there is a blind spot in the winch where
the glider disappears behind the top frame of the winch cab. This is
the point where you need to start to think about reducing the power.
As the glider re-appears from this blind spot start to reduce the power
gently but positiverly in order to allow the pilot to lower the nose
to reduce tension in the cable and release. Reduce the power too quickly
and the cable will back release, too slow and the pilot may "hang
on" a bit too long. The exact point of this power reduction comes
with practice and depends on the weater conditionas at the time.
It is at this point where you should place your free hand on the appropriate
frum brake.
If you find when you are laucheding that gliders are always back releasing
then this could be a sign of , taking the glider too hight, reducing
the power too quickly or, of the pilot being slow to react to the reduction
in power. Consider which of these may be the case and react accordingly
- the aim is to always allow the pilot to release the cable. Back releasing
is a safety mechanism and should not be treated as the norm.
Once the cable has been observed to drop away from the glider them
power can be reapplied to pull the cable back in. Aim to use a half
to two thirds power of just enough to get the parachute infated and
to allow the cable to feed into the drum smothly without coiling up
on the ground in front of the winch. Initially you may have to apply
up to full throttle to get "things" moving, bus once going
back off accordingly. Only use full power is absolutely necassary.
At about 200 to 150 ft from the ground ease off the trottle competely
and gently apply the drum brake so the paracute drops to the ground
dead or at worst case at a slow waling pace. The reason for this are:-
- It forms a habit. at some stage you may find the parachute or cable
is about to drop on some one or something. If this is the case then
it is far better that the cable / chute is "dead", as it
causes less damage than if is under power. If you are already in this
habit then at times of crisis you won't be under extra pressure to
do something different.
- It cust down on wear and tear of the parachute and associated bits
and pieces as well as damage to the grass, runway, crops etc.
If you do not think the parachute is not going to clear an obstruction
of it's marginal then best option is to cut the power and brake the
drum in plenty of time.
Wind In
Once the parachute is on the ground, double check that you have your
hand on the correct drum brake and wind the cable in on tick-over only
because:-
- If you have to brake quickly you can without the risk of throwing
a loop.
- It allows the feeder pulley to slow down gradually thus reducing
wear on both pully and cable. This is not so much of an issue though
since we have changed to plastic pulleys.
As the cable approches the point where you wish to stop the parachute
apply the drum brake gently and in good time. Once stopped, apply the
transmission brake, then release the drum brake and dis-engage from
gear. Now re-apply the drum over-run brake.
Prior to the cables being taken back to the launch point it is usually
a good idear t check both drums first to ensure you havent't trown a
loop which could cause problems on the pull-out.
As already stated the above is the method best used for a K21. Some
gliders however require a slightly different technique. To describe
each technique for each type of glider we have on site would take aproximately
forever to write so, the next method is for single seat woodern gliders
such as the K8.
Up slack is as for the K21, only you may need to use a bit less power.
all-out is generally to the first stop or just bejond dependat on conditions.
Once the glider has rotated then to avoid the sudden pitching up of
the nose that can occur on these types, reduce the throttle setting
slightly. Note the aim here is not to reduce the power as such, but
to keep the acceleration in check. Once you start to here the engin
start to take the strain of the glider then gently re-apply the power
to the first stop, (or bejond dependat upon conditions), and keep it
there untill the top of the launch. The rest should then be a La K21.
Pilots please note:-
- Decide which type of launch you are comfortable with bearing in
mind the type of glider you are flying for example if flying the junior
then I normally request a K8 style launch, the discus then slightly
faster than a K8. Decide what you want and ensure the winch driver
is made aware.
- A good or dad aunch isn't always down to the winch driver. A good
launch is a team effort between both pilot and winch driver so think
about your own possible failings before blaming it on the poor old
winch drivers. If in doubt how to launch a particular glider then
ask. Also it is a good idear for anew winch drivers to get feedback
from pilots about their launches. This can be satisfying when all
is well but also depressing when not. Either way it's a good learning
tool.
Cable Breaks
A cable break simulated or otherwise should be ovious. You can usually
feel the cable break and at the same time the engine speed increases
as it looses its load at the other end of the cable.
Action- Let go of the throttle and gently but firmly apply the relevant
drum brake. Allow the parachute to drop to the ground and disengage
gear. Then wate to see what action the glider takes and awate further
instructions. DO NOT attemt to pull in the cable untill you are absolutely
certain the glider and cable will be or are clear of each other. Safest
option is to let the parachute drop dead as already described and wait
for the glider to land and react accordingly from there.
Generally
When operating the winch, be smooth and sympathetic to the machinery,
do not bang and crash about, It's not a race.
Whilst winching, ensure both cab doors are closed and locked. The cab
is your safety cage and will protect from loose ends of wire that thrash
about during cable breaks.
To speed things up, if practical and safe to do, put the "used"
cable on back of the appropriate side of the tractor in-between launches.
Be aware of what is going on around you, there may be instances where
it is un-safe to launch despite the request/instructions from the launch
point e.g. walers, gliders sneeking in from a different direction.
If in doubt do nowt!
Andy (Mr. Winch) Butler
from the Wolds gliding club
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