… the faster you write, the easier your message will be read from the ground.
THE HARDWARE REQUIRED
1. A tank to hold the smoke oil.
2. An electric pump to pump the oil.
3. A simple, aircraft quality switch to
turn the pump on and off.
4. A means of getting the oil inside
the exhaust pipe.
5. Hoses to connect the tank to the pump.
6. Hoses going from the pump, through
the firewall, to the exhaust pipes.
7. FAA field approval for a certificated
airplane. Experimental aircraft do not
need approval.
around with smoke, a gallon or two will be
fine. The pump needs to put out around
20/30 psi; most fuel pumps do not work or
they cost a fortune. I have had good results
with Shurflow pump model number 100-
009-21. It’s a 12-volt water pump, available
from recreational vehicle dealers. Find more
information at www.Shurflow.com.
Be sure to use a fuse or circuit breaker for
your on/off switch.
Here is the secret to getting lots of smoke.
Throwing oil inside the exhaust will produce
smoke, but if you can spray that oil into the
pipe in a 180-degree-wide, razor thin arc,
you will get a lot more smoke because it burns
better. I invented a smoke oil
injector nozzle. It attaches
to the exhaust pipe just like
an exhaust gas temperature
probe with a hose clamp. Drill
a 1/4-inch hole in the exhaust
pipe in any convenient spot,
before the pipe reaches
the muffler, and insert the
injector and tighten the hose
clamp. Two injectors are
better than one, actually.
make the two legs of the letter first, at the
same altitude, then descend approximately
30 feet and come back for the cross bar on the
letter. From the ground it will all appear to be
on the same horizontal plane. If you had gone
over the line, your wingtip vortices would
destroy it.
After each letter drop down about 50
feet before making the next letter to give
yourself a better view of your work. If you
stay at exactly the same altitude, you are
seeing the knife-edge view, which is lousy.
The 50-foot difference in letter height will
not be noticeable to people on the ground.
The tank should hold a minimum of 5
gallons of oil for skywriting; for playing
Aircraft fuel hose works
well on the cool side of the
firewall. We only have about
20 psi of pressure so low
pressure hose is okay. On
the engine or hot side of the
firewall you should use high
temperature hoses and/or fire
sleeves.
REGULATIONS
I do not know of any provisions in the
Federal Aviation Regulations concerning
skywriting, so we have to rely on common
sense and courtesy as guidelines. It is
advisable to contact your nearest radar
facility or flight service station if operating even close to controlled airspace. This
is where a transponder comes in handy. If
you call the radar facility as you are climbing out, the controllers there will usually
assign you a transponder code, and that is
about all you will hear from them.
However, review any NOTAMS for possible temporary flight restrictions (TFRs)
that might affect your activity.
Make a drawing and
materials list before you
put a smoke-oil system on
a certificated airplane and
let your local mechanic and
FAA representative work
together to get approval. For
experimental aircraft owners,
use the same common sense
as when you built your
airplane to make sure your
installation is safe.
AIRCRAFT
Personally, I prefer to skywrite flying a low-wing plane with a bubble canopy because of
all the sharp turns. My reasoning is that you
must look back behind you while in a steep
bank to find your smoke trail. You must be
able to find your previous smoke trail while
in this steep turn so you can go back and
intercept it to make the remainder of the
letter. This is hard for me with a high wing
blocking my view. But I know people with
Cessnas and Decathlons who do a fine job,
so don’t rule out high-wing planes.
You do not want a fast plane; its turn
radius is too large. High horsepower in a
slow plane is perfect, but we seldom have
that perfect plane in our hangar. I started
out skywriting with a little two-seat
Grumman trainer, a TR- 2 with 108 hp. You
