Formation
Flying
Formation
flying is something that not very many civilian pilots do, with the exception
of pockets of homebuilt RV pilots here and there, who frequently have some
ex-military pilots at their core.
Military
pilots receive training in formation flying, and their skills vary, depending
upon what kind of flying they did in the military. However military pilots often fly formation
in a very particular manner (eg similar types,
stepped formation, positive G only, etc).
In the
civilian world you will find a wild variety of skill and proficiency in
formation flying, from zero to highly expert.
As such, you have to be very careful with whom you fly formation
with. The good news is that you can size
up the formation skills of any pilot extremely quickly (within seconds), but
I’m getting head of myself.
Let’s
consider the basic element of two aircraft, which is how you should learn to
fly formation. It is suicide to learn to
fly formation in a large group, because the potential for something horribly
wrong goes up exponentially with the number of aircraft in the formation.
In a two
aircraft formation, one aircraft flies the “lead” position, and one aircraft
flies the “wing” position. They are very
different activities.
Lead
Pilot
The lead pilot
is responsible for the safety of the formation and must worry about fuel burn,
navigation, airspace, traffic and NOT hitting the ground. He must fly smoothly and must think well
ahead, because he cannot manoeuvre as sharply as a single aircraft can, because
he will throw the wing off.
The lead
pilot is actually flying a very large aircraft – the entire formation - and as
such can use high angles of bank and pitch, as long as he keeps his rate of
change of pitch and bank low, to give the wing pilots time to keep their
position.
Ideally the
lead pilot should be the most experienced pilot in the formation – he should be
an expert wing formation pilot. That’s
the way it is in the military.
Unfortunately in the civilian world this is usually reversed – generally
the most experienced formation pilot flies wing, and the least experienced
pilot flies lead. This can lead to
horrible consequences. Free advice: never fly wing on a someone unless he is a
better pilot than you, because you are trusting your
life to him.
Wing
Pilot
While the
lead pilot’s job can be roughly described as not hitting the ground, the wing
pilot’s job can be similarly described as not hitting the lead.
Flying wing
is a hand-eye co-ordination stunt, a lot like standing on a basketball. It doesn’t require a lot of brains to do it,
but it requires pretty good hands and feet.
There is simply no substitute for practice when it comes to flying wing. The more you do it, the better you will be at
it. Please have realistic expectations
about your performance. There has never
been a single human being in the history of aviation that didn’t get good at
formation flight without an awful lot of practice. Don’t expect to be the first, ok?
The wing
pilot should maintain a constant position, by maintaining a sight picture,
which is defined as keeping parts of his airplane lined up with parts of the
lead airplane, regardless of how the lead pilot manoeuvres. Most people start out with the classical 45
degree echelon, with the wing aircraft aft of the lead on the right side. Please try to spend an equal amount of time
on the left side. Some formation pilots
will only fly one side, which is about as ridiculous as a NASCAR driver that
can only turn left.
Military
pilots will often “step” the wing aircraft down, which is a something I would
expect from someone with a rainbow sticker on their car. We fly formation level, for several reasons. Put your wingtip next to the lead’s tail, and
your spinning prop next to his wingtip, and get used
to it.
Another
formation position – which is a favourite of mine but rarely used – is line
abreast. It not only looks symmetrical
with two aircraft, it also has the huge advantage that both aircraft are doing
exactly the same thing during vertical aerobatics. Most pilots don’t like line abreast formation
because there are fewer visual cues to help the wing maintain position. It’s easy for the wing to get bank on and not
even know it. Not only does this look
ugly, it creates drag for the wing which is a performance penalty for him. The lead pilot must continually coach the
wing pilot to keep his wings parallel to the lead. It is a skill that comes with practice.
Aircraft
Most people
think that formation flight is easier with identical aircraft, and this isn’t
really true. Ideally the wing aircraft
should have a huge power advantage over the lead aircraft, so the lead pilot
can shove his throttle all the way forward and dive and turn away from the
wing, so the wing can use his extra power to stay in position. With identical aircraft, if the lead pulls
that dumb a stunt – going WOT with the wing flying a larger radius and thus a
greater distance – he will shake the wing off, which is stupid.
Flying
Lead
The lead
pilot must have a lower power setting than the wing when he is turning away
from him, to give the wing some extra power to fly the higher speed on the
outside. The military way is for the
lead to run a continuous less-than-maximum power setting, but that’s severely suboptimal
and simply won’t work in the piston/prop world, where there isn’t incredible
excess thrust available. A good lead
will reduce his power when he turns away from the wing, and increase his power
when he turns into the wing, in order for the formation to maintain maximum
energy. In effect the lead pilot is formating on the wing with respect to power, which is
military heresy. Get over it.
The lead
pilot must never fly in such a manner so as to leave his wing pilot helplessly
behind at full throttle, nor must the lead ever cause the wing aircraft to
stall, which is quite possible if the lead turns into the wing at slow
speed. The wing is now flying a smaller
radius than the lead and thus at a slower speed and thus at a higher angle of
attack. I once had a very poor lead turn
into me at slow speed and low altitude.
If I had stuck on his wing, he would have killed me, when I stalled/spun
during the turn he had attempted. See
above note about never flying wing on a pilot unless he is a better pilot than
you.
Flying Wing
As
mentioned above, the job of the wing pilot is to maintain position while not
hitting the lead aircraft. He does this
by never taking his eyes off the lead aircraft until he gains considerable
experience, and then only for a very brief moment.
The wing
pilot ideally anticipates the movement of the lead aircraft. This is often not possible, and if the lead maneuvers gently enough at a low enough power setting,
doesn’t matter.
When the
lead pilot turns away from the wing – watch the lead’s head and ailerons – the
wing must immediately add power for the increased radius he must fly, and
simultaneously pop up with back stick in order to maintain the same relative
position to the lead.
When the
lead pilot turns into the wing, the wing must immediately reduce power and push
forward on the stick in order to maintain the same relative position to the
lead. This sounds complicated but like
screwing, once you do it a few times it will become automatic.
As you
might imagine, the above is an ideal receipe for a
PIO – pilot induced oscillation, caused by over-controlling. It is easiest to fly formation in smooth air
– you can hope for a cloudy day with an inversion, or fly early in the day, or
climb above the base of the first layer of clouds if you have plenty of
power.
If you fly
formation in smooth air, every movement of the wing’s aircraft will be a result
of your inputs, which is educational.
Flying formation in bumpy air is work, and takes practice to get any
good at, because you are continually being pushed out of position by the bumps
and must continually correct for it.
Most people find this very tiring.
If you fly formation in the bumps, dial in some more nose
down trim. I usually fly wing with a
constant 5 lbs of nose-down pull on the stick to dampen out the natural PIO
tendency in pitch. With bumpy air,
increase it as required to 10 or even 20 lbs of pull. At the end of the flight you will be
exhausted, sweaty and you will swear that your right arm is 2 inches longer
than your left. That means you are doing
it correctly.
Most people
find flying close wing tiring under any circumstances at first. Although it is military heresy, it is
efficient to trade the lead position back and forth during a training flight so
both pilots get practice at both positions, and a rest.
Wing
Position & Visual
Above I
mentioned two common formation positions for the wing: classical 45 degree
echelon and line abreast. Note that I
specifically did not mention the lateral distance between the two aircraft.
Beginner
wing pilots like to give themselves lots of lateral room from the lead, to give
them a false sense of security. I call
this the ``comfort zone``. This is a
very poor choice, because the farther out the wing is from the lead, the harder
it is to keep position because of the “crack the whip” effect – the wing will
have to manoeuvre with ever-larger displacements in the vertical during turns,
the farther out he is.
Also, there
is a fatal trap with being farther out.
Because of the reduced visual cues and the common tendency of the wing
to relax and bury his head in the cockpit when he is positioned farther out,
horrible close rates can develop. This
simply doesn’t happen when the wing is tucked in tightly; the lead aircraft is
huge, and the wing pays complete attention to flying formation.
Now, on
occasion the wing pilot will have to stick his head in the cockpit briefly, and
not look at the lead. A good example of
this is a radio frequency change. The
wing does this by temporarily sliding out – NOT back – performing the frequency
change, and then sliding laterally back into
position. It’s neat to watch a vic formation (lead with both
right and left echelon aircraft) quietly do this. Note that a wing aircraft never slides back,
for two reasons: he might not have
enough excess power to move forward again, and the wing must always be in sight
of the lead pilot. If the lead can’t see
the wing, he must assume that the wing has quietly fallen out of formation and
must now go look for him.
I should
mention that there is something called battle formation, which is used by the
military to manoeuvre a formation with all aircraft at high power settings, but
that is outside the scope of this article which merely concerns itself with
close aka parade formation.
Joinups
One last
thing I should mention in this article – God, I skipped over so much stuff – is
that you probably won’t be taking off and landing in formation when you start
your formation training. That comes
later.
So, if
you’re going to take off separately from the lead, you’re going to need to
learn how to join up on him, into position.
This is non-trivial and has really nothing to do with close formation
flying. It has more to do with
air-to-air combat. You know, that
Knights Of The Sky silk scarf crap, except in a
formation joinup the lead pilot isn’t trying to stop
you from maneuvering into position on him. He should try to make it as easy as possible
for the wing to get into position on him.
The worst
thing a lead pilot can do during a joinup, is fly straight and level at a high power setting away
from the wing. It’s going to take all
day for the wing to chase the lead down in that situation.
What a lead
pilot does during a joinup, is fly a gentle turn at a nice safe altitude – NOT down
low. This allows the wing pilot to turn
inside of the lead pilot, and aim ahead of him.
The wing pilot should dive down until his aircraft is on the extended
plane of the lead’s wings, and slide up into position on the lead. As you get more and more practice at joinups, you can do this faster and more aggressively. When you get really good at it, you can take
a great bloody run at the lead and do a barrel roll around him, into position,
which is probably one of the top ten fun things you can do with your pants on. This is not an advisable manoeuvre to perform
without considerable formation and aerobatic experience.
To
understand what’s going on in a joinup, you need to
understand just a little bit of physics, because that’s what you’re doing: applied
physics. If you understand it just a
little, it will go well. If you don’t
have a clue what you’re doing, it’s going to go badly.
The total
energy of an aircraft can be expressed as the sum of the potential energy (due
to height) and kinetic energy (due to airspeed). One can easily be converted into the other
and back again, and that’s exactly what an airshow
pilot does: fast and low at airshow center, and high
and slow during the reversals at the ends of the box, as he drives up and down
the runway.
For a
successful joinup, both the lead aircraft and the
wing aircraft must have the same total amount of energy. If the wing attempts to join the lead from
above, at the same (or God help you, faster) airspeed, when he descends to the
lead’s altitude he will have gained airspeed from the lost altitude, and he
will blow past the lead like the lead is tied to the guardrail. Not cool.
Even trying
to join without turning at the same altitude can be tricky, because although
both aircraft have the same potential energy, the faster wing aircraft still
has more kinetic energy than the lead, and again he will likely blow past the lead
when he attempts to join up, even if he hauls the throttle all the way back to
idle.
So for both
aircraft to have the same amount of total energy – which means they will go the
same speed when they are at the same altitude – the wing aircraft should be
lower and faster than the lead aircraft.
As he slides up into position on the lead, he converts his excess
airspeed into altitude and if he does it right, slides nicely into position.
But what
happens if he doesn’t? No big deal,
because the lead is the only other aircraft in the sky – see above about big
formations – and if the wing overshoots, he merely pushes forward on the stick
(even though negative G is unpleasant, let gravity help you), slides under the
lead, and joins up on the outside. The
wing can then claim that he meant to do that.
The lead won’t buy it, but it can’t hurt for the wing to try it on him.
Anyways. I have barely touched on the very basics of
non-aerobatic formation flying, which is a fascinating and rewarding
sub-discipline of aviation all it’s own. Try hard not to kill yourself or anyone else
while you’re doing it.
--
acboyd@gmail.com Oct 2011