Pike Setup Steps by Jo Grini
Setup - Tips and
tricks of the trade!
Here are a few tips and tricks on how to setup a
Pike model. They will not help you win a contest but will give you a few hints
on how others do things.
How to set up a full house sailplane
There are a lot of FAI models out there. I am
sure that there are many models out there that is not used to their full
potential. This article might help slightly to get them work that air a bit
more.
There are a lot of ways to set up a model for the classes F3F, F3B and F3J. So
do not see this as a recipe on success but maybe a good guide on the way. What
functions are we after? I reckon you the pilot have got yourself a modern
computer radio and a plane with 4 servo wing. I see this as a minimum to have
fun on the flying field... These are the controls we are after: Aileron,
elevator, rudder, brake (called butterfly) and flaps (camber).
Aileron:
We wish aileron on all wing surfaces. To fly only thermal one can only use the
outer surfaces (ailerons). But as soon as we are on to F3F/F3B we want apx half the amount aileron deflection on the inner
surfaces (flaps). Differential: To make a model turn better in a given speed we
need to use a function called differential. This function (or mix) makes the
ailerons and flaps go less down than up. Differential can even make the model
yaw every time we use the aileron stick. The result is a kind of rudder. You
will most likely want different differential at different flying speeds. As a simple guidance for thermal flying: 1/3-1/2 down versus 1 up.
Speed and acro: 1/2 or equal down versus up. In speed
acro you want the model to roll straight in the given
speed. In F3F some want the model to yaw in before the turn but mostly this is
done by rudder.
Elevator:
As a main rule you want equal amount up elevator as down. But it is so that CG
(central of gravity) and construction have something to say here. It is also so
that a more aft CG should have less elevator throw. Be
aware of this as one often changes the CG in different tasks. If the model gets
very sensitive but one still wants the throw you can: Have less down elevator
or use exponential. Exponential makes less throw around "dead-stick"
but will give you full throw with the stick in either position.
Rudder:
The rudder is worth a chapter for itself. Sadly there are not many pilots that
have learned to use the rudder. The rudder is there to keep the model in the
flying direction and preventing it from yawing. The best way of understanding
the rudder function is to take a flight with a full size sailplane. In the
cockpit glass you will see a wool thread just above the pilot. This shows the
wind direction compared to flying direction. All other cases than that the
thread goes straight backwards is big loss in energy and thereby
speed/altitude.
T or X-tail rudder:
Equal to each side but not more than that it
actually works. Too much and the rudder will only slow you down or make it
tip-stall. V-tail rudder: Equal up/down but also here there can be some
differences in models. If the model sets its nose down much you can reduce the
down slightly. But not too much as it will give you a wrong feeling when
circling.
Combi-switch:
Sadly there is a mix that is called combi-switch that many finds on
their radio. This is often miss-used. It will give you rudder movement when you
use your ailerons automatically. This is fine coming into a turn but will have
the opposite effect compensating or coming out of the turn. So turn this mix
OFF. There are two times you might want it to be on: - When flying F3F competition
and you are a good pilot you might want it but only slightly as a help. Any
compensation of flight path between the bases will result in wrong input. - In
the launch mode it can be used if you use a separate launch mode on your radio
(
Brake:
This I would like to call butterfly or crow on our sailplane models. When
flying the brake is like an motor for us. The
butterfly function should be on your throttle stick. Forward full speed and
back for brake. With full brake the following should happen: Ailerons slightly
up (5-10mm), flaps as far down as possible and elevator slightly down as
compensation for the increased lift in the wing. There is no
"hocus-pocus" with butterfly but often a little work to get the
correct elevator compensation. Even full size airplanes use butterfly.
Compensation on butterfly should be dialed in at both half and full brake. The
model should put nose slightly down to maintain airspeed. Often a model will
need more compensation on half brake than full. If not possible to set two settings
then reduce the flap to 60-70 degrees. Mostly this is sufficient to give enough
brake anyhow.
Flaps:
3 kinds of flaps are wanted and also the kick-flap as mentioned in the elevator
section. When I write about flap I now mean all surfaces on
the wing not only the "flaps". Camber is a good word and means
changing of airfoils lift.
Start camber:
When we start with winch/runners one needs to
have a bigger camber / more lift on the wing than the model is produced with. This because the model will work as a kite not a flying model.
Before the zoom we want to use the energy captured in the line and turn this to
"flying energy" = speed. Dependent of model type and condition you
will need 10-30 degrees launching camber. The launching camber is also
dependent on where the hook is and the position on the elevator. We might need
to set up different settings for different type of conditions. In strong
headwind you need less camber and the hook seated so that the model will
increase the tension on the way up. You will hopefully hear the line tension
and speed increases on the way up. Mostly pilots have the same settings for
normal conditions and strong wind. In poor launching conditions (wind from the
back, high altitude or more ballast) you might need more launching camber and
the hook should not be to far back. In these conditions we mostly try to use as
little line as possible and this is done by line tension not speed. As a
general rule you want equal camber on flaps and aileron surfaces. Many use less on the ailerons but this is wrong and can make
your model "yaw" on the line or maybe tipstal.
If the hinge line on the aileron surfaces are much less then try to figure out
if the degrees of camber is the same. So
aileron camber can be less if the angle is the same. The hook is normally seated just in front of
the pressure center of the wing. The pressure center will alter much when you
add camber. The CG has
almost nothing to do with hook placement. 50-100kg of tension will take away
any effect of CG. You will want the model to rotate heavy just after the throw.
With too far aft hook the model will over rotate and "pop-off" giving
you a relaunch. Too far back will also make the model
be "forced forward" in the air and your winch will "eat"
valuable line length. Always start with recommended settings from the producer
or a pilot you think knows better. Add/reduce launch camber until you are
satisfied in one type of conditions and write this down. 5mm altering of the
hook can make as much as 50m launch height so use much time on launch practice
in different conditions. A good launch on a F3B winch in calm conditions is
230-250m. In good conditions one can achieve 300-350m and the opposite in
backwind one can have 180-200m or even only 150m sometimes. As a main rule one want just as much launch
camber on ailerons as on flap. But on some models you want slightly less as the
hinge line is different. The point is that we do not want wash out on a wing in
launch as this is only drag. We want the whole wing to fly all the time. I must
take hook setting at the same time because camber and hook works together. The
hook should sit just in front of the pressure point in the wing and this will
change a lot with different camber. Most often we set the hook just in front of
the CG but as mentioned it can vary a lot. Since the pressure point in
different settings normally is not given one should start with the recommended
setting or make contact with someone that have flown
the same model for a while. Launch camber, hook placement, etc. is a difficult
issue to handle and I cant give you a 100% correct
answer as all plans are different. But a few facts must be stated: More camber
= more backwards hook. More start flap = you go slower up the line. You want to go as steep climb as possible but with the
highest speed possible. At the same time you want to stretch the line to build
up a bungee effect for the zoom. The more stretch - the better height you will
get.
Launch camber is normally set with a switch and some like to adjust it by a lever
previous to the start (to set for different launching conditions. The switch
needs to be with easy access and equal on all your models so that there are no
hesitation when you switch it off just before the zoom.
Speed flap: When flying speed and distance we often want a faster airfoil. How
much depends on the conditions you are flying in and type of model. It is done
by all surfaces on the wing goes up 1-5 degrees. Mostly on only uses one
position or neutral.
Thermal flap: When flying duration and partly distance we want to change the airfoil so that it becomes more lifting (1-10 degrees). This is done by all surfaces on the wing is going down. How much is depending on a lot of factors. As a main rule we want more camber the better air you are flying in. For moving around you want as little as possible (in most air conditions but this might change at altitude). When you find the lift you use as much as possible but not so much that the model becomes "low tail" or critical to fly. Most pilots adjust thermal flap by a switch or maybe two. Some likes to also adjust it on a lever. But mostly you want as few switches as possible. The difference is anyhow mostly on the pilot control. So how many switches/settings are we up in now ? Start camber: 3 positions - launch/neutral/much wind.
Duration:
3 positions - Strong thermal/neutral/small thermal. There are many solutions to setup of switches and often each radio provides "their ultimate" solution. For the most advanced radios I can supply my own setup that I think works fine. Only two switches: One 3 point and one 2 point switch seated on top left of my radio. I use these switches to control my flying modes. So many things happen at the same time when I switch one of them. - Switch one have the following functions: Forward - speed mode, Middle - neutral flying, Backwards - Launch mode. - Switch two have the following: Forward - switch one is working, back and you are overriding switch one and are in thermal mode with positive camber. All camber can be adjusted by my lever.
Hope all this txt gave you some
new ideas. Remember one can always develop further and all needs to find
"their setup".