Natescape: Aerobatica
Overview
On a neighboring page you'll
find a long list of basic "precise control" exercises, put together by
Alan Kait and Mike Davis. What follows is my effort to extend their ideas
into aerobatic flight.
From here the possibilities increase radically (pun intended). For
each maneuver listed in the "Sequence" and "Simultaneous" sections, there
are a host of variations possible if you start from an orientation other
than the basic "spinning side up, canopy forward" stance.
Basics
For those of you just getting comfortable with the essentials of
hovering
and forward-flight circuits, basic aerobatics might just be your logical
next step.
The most obvious basic maneuvers are the classics borrowed from
airplane aerobatics: loop, roll, stall turn, and pirouette.
In addition, I think the moonslide (a.k.a. "tumbleweed")
belongs in this category, since it's a close cousin to the loop and you
learn a lot about using rotor thrust in tumbling maneuvers. A moonslide
is essentially a backflip in fast forward flight. It works something like
a loop, but you time the collective movements so that your speed and
altitude remain constant. From fast forward flight, try dropping to full
negative pitch and pulling full back-cyclic - as the rotor disk passes
through the knife-edge orientation, the negative pitch acts to "suck" the
helicopter forward. Bring the collective back to full positive as the
heli continues to flip, and practice until you can tumble during a fast
pass, losing as little speed and altitude as possible.
As you learn these basic maneuvers, you'll probably also be learning
about (and just plain working on) your helicopter's setup. Flight modes, main rotor setup, and tail rotor setup all become much more
interesting as you begin to ask more and more from your helicopter.
Orientations
And you thought nose-in was a milestone! Inverted hovering, backwards
circuits, inverted circuits, sideways circuits, backwards inverted
circuits, backwards sideways circuits... Just hovering and forward flight
become challenging all over again when you flip the helicopter over or
point it another direction (or both).
Sequences of Basic Maneuvers
What to do when you've become comfortable with basic aerobatics? Take
them apart, mix and match at will. Build aerobatic sentences from the
vocabulary of basic maneuvers...
540 Stall Turn
A stall turn with an extra pirouette.
Rolling Stall Turn
Essentially a stall turn with a half-roll between the entry and the
180. Consider the sequence: 1/4-loop, 1/2-roll, 180, 1/4-loop.
Immelmann
Sequence: 1/2-loop, 1/2-roll.
Fickle-540
1/4-loop, 180, 360 in the opposite direction, 1/4-loop.
Markingover Kinerturn
1/4-loop, 1/2-outside-loop in the opposite direction, 1/2-roll,
1/4-loop. Think of it as a rolling stall turn, but with a
half-outside-loop in place of the half-pirouette. Ideally the helicopter
is
traveling straight up, backwards, during the beginning of the half roll.
Mark Kiner watched someone do this, mentioned it on the h-list, and got
everyone enthused about it. I'm not sure who dubbed it the "Markingover
Kinerturn," but that stuck in my mind...
Cuban Eight
5/8-loop, 1/2-roll, 5/8-loop, 1/2-roll. This move was taken directly
from airplane aerobatics.
Wadd-ooops
1/2-loop, 180, 1/2-roll. If you do it right you'll maintain the same
speed, altitude, and heading through the maneuver. I made this up and
asked the h-list for ideas to name it. My last name made the answer
obvious...
Moonstall
Starts with a moonslide, but hold full negative cyclic so the heli
starts to climbs tail-first three-quarters of the way into the slide. Let
momentum carry the heli straight up tail-first until it stalls. Then do a
half-roll and exit as if from a rolling stall turn. I made this up too,
but I didn't ask for help naming it.
Basics with new Orientations
Imagine the rotor disk following a familiar path - as in a roll, for
example - with the tail boom pointed in a non-standard direction.
Sideways Traveling Flip
Begin with wide-open-throttle fast forward flight, yaw 90 degrees to
get the boom sticking out sideways, apply full back cyclic and work the
collective to keep the heli traveling in a straight line. With a
heading-hold gyro, it's really no more difficult than a simple roll (but
still easier said than done).
Half-Axel
I want to describe it as a knife-edge moonslide...
From fast forward flight, pull up to knife-edge like the first quarter
of a moonslide, with full negative collective. Half-roll, reversing the
collective to keep your momentum up, push forward and exit upright and
tail-first, ideally with the initial speed, altitude, and heading.
I'm pretty sure you could do a full axel, but I haven't been able to do
one with any smoothness at all. You have to work the collective like a
moonslide, but the tail boom points straight down the whole time. I'll be
working on this one during the coming summer...
Simultaneous Basic Maneuvers
Ready to really start taxing your brain cells? If five
basic tricks in a row sounds too easy, try doing just two of them at once.
Rolling Circle
Sounds plain enough - just do a bunch of rolls (easy enough) while
doing a forward-flight circle in front of you (easy enough). What a pain
in the brain. I'm still struggling with this. I've never made it more
than three quarters of the way around the circle before running out of
speed or running out of nerves.
Pirouetting loop
It's possible to do a single loop with several pirouettes throughout.
I've never managed, but it looks like you basically move the cyclic in
circles while working the collective just as with a standard loop.
A loop with a single pirouette wasn't as hard as I had feared. You
can take it one quarter at a time... Note that through this process you
still need to work the collective as with a standard loop:
- first quarter: pull back. add left rudder, gradually move from
back-cyclic to left-cyclic. At this point if you want to bail out you can
exit as if you were in the middle of the 180 of a stall turn.
- second quarter: hold the left rudder, gradually move from left-cyclic
to forward cyclic. At this point, you're coming over the top of the loop
tail-first. If you want to bail out, you can can release the cyclic, add
more rudder, do an inverted 180 and fly away nose-first inverted
(half-roll at this point makes it rather like a fancy immelmann).
- third quarter: continue holding left rudder, gradually move from
forward cyclic to right cyclic. A non-heading-hold gyro, is helpful here,
since after this point you can ease up on the rudder and let the
helicopter weathervane for the rest of the loop. If you've made it three
quarters through the loop, it's easier to complete the maneuver than it is
to attempt some sort of bail-out.
- fourth quarter: are you seeing a pattern yet? Gradually move from
right cyclic to back cyclic and exit as if from a standard loop. Again, a
standard-mode gyro will allow the heli to weathervane, which makes the
last half of the pirouetting loop a little bit easier.
Rolling Loop
I watched Curtis Youngblood do one of these at a fun-fly a while back,
and was amazed. He set up the move with a dive from left field to build
up tons of speed, and proceeded to amaze me. I'm still trying to figure
this out, but here's my approach so far:
- start with as much speed as possible - a diving approach from left
field works quite well
- straight and level fast forward flight
- half-roll to inverted (it's a rolling trick, so start now!)
- push forward, aiming vertical (like an outside loop)
- half-roll
- pull back, aiming over the top of the loop (like an inside loop)
- half-roll, so you're upright over the top of the loop
- push forward, pointing straight down (like an outside loop)
- half-roll
- pull back, aiming back along the way you started (like an inside loop)
- that's the end of the loop, but another half-roll (or more) continues
the theme nicely.
The most difficult part (for me) is around step 6. At this point, the
momentum is running out and the helicopter is too busy changing
orientation to keep its speed up. Keeping a circular trajectory is a
challenge. More initial speed helps. A fast roll rate
helps. Cheating helps: before pulling back, give it full positive
collective to get it moving over the top of the loop (looks bad because
the boom is pointing straight down). Or pull back almost 180 degrees and
use lots of negative pitch to add speed and altitude (looks bad because
it's a snappy half-flip in what should be a slow, graceful maneuver).
'round the world
This is something I came up with when I was working on the pirouetting
loop. My brain froze, but it looked cool anyhow so I kept working on it
(thank goodness for simulators!). From fast forward flight, pull up to
about 45 degrees, give a bit of rudder and a bit of aileron in the same
direction, and hold both while working the collective somewhat like a
loop.
The helicopter's trajectory is next to impossible to describe with
text, since it happens in three dimensions... It looks a bit like a
sideways loop, only the loop is perpendicular to the entry and exit; if
you enter the trick flying away from you, the loop is a vertical circle in
front of you. Be ready to give it a stab of forward cyclic and a quick
180 at the end of the loop, and exit the way you came. This is a nice
"turn-around" trick, try doing them back-to-back at opposite ends of the
field.
Stay tuned, I'm still working on this...
click here to send me a message
To link directly to this page:
http://www.natew.com/rcheli/frames.cgi/html.Aerobatica
| Printer-friendly
colors, sorta...
|
Printed with recycled
electrons.
Because I care.
