. My question is, does anyone know of a method of pre-heating the engine
prior to start. I have heard of a heated oil dip stick for cars that are
very popular in the northern states where the temps are below zero in the
winter, I am wondering if such a device is available for aircraft?????
>Bob Stone,
++++++++++++++++++++++++++++++++++++++++++++++++++++
The problem with heated dip sticks or the oil pan heat pad, as I
see it, is the heat is too concentrated to warm the entire engine
as you want and the heated pad can actually "cook" the oil if
the pad is hot enough. A much better solution is to warm the
entire engine, not just the oil.
I've built several engine heaters that are really inexpensive, easy
to use, and safe. A friend of mine photographed me building one
for his C-170 and it was written up in the C-170 Club newsletter.
The advantages are:
Safe - heat source well away from the engine.
Easy to use - just slide it under the airplane and back out
when you are finished. It is self-standing and
requires no hook-ups.
CHEAP - materials will cost you about $5 plus the cost of
a good quality 1500W ceramic heater, the kind that
is about 8" X 8" or so.
Easy to build - you can build it in an hour or less.
It is easy enough to build that you should be able to assemble it
from the following discription.
Go to your local building supplier and get one sheet ( 4' X 8' ) of the
foam insulation board with the foil cover on both sides. The 1/2"
or 5/8" thick is sufficent. You will need approx 6' of the 8' length so
try to buy a damaged piece if they have one for about half price. Even
an undamaged piece should sell for approx $5. If you don't already
have one, pick up a good quality ceramic heater with a fan, the small
square kind that are usually rated for 1500 watts. They should sell for
about $25. Mine has hi/low heat settings and tip-over shutoff switch.
Measure the distance from the hangar floor to the bottom side of
the opening at the rear of your cowl and the outside dimention of
the heater. A slight modification on the top end of the heater
tube may be in order, depending on the cowl opening.You are now
ready to start construction.
Basiclly, what you are going to do is construct a square heating
tube, the outside dimention of your heater, in the form of an L.
The heater should just slip in one end and the other sets under
the cowl opening. You construct it from flat panels cut from the
foam board and tape it together with "duct tape" or the foil tape
used for duct work. Either one will work.
The horizontal run of the duct should be approx 24" long to keep
the heat source well away from the engine. The vertical run is
the distance measured earlier. Draw the two side pieces of the
L and then the other panels needed to finished the duct on the
board and cut with a sharpe knife. Instead of a full 90 degee
corner in the duct, I made mine with a couple of 45 degree bends
to better help the airflow. Just draw the side pieces the way
you want the shape to be. When finished, the heater should
just slip inside the duct.
As for modifing the top end, the C-170 had a gascolator centered
in the opening of the bottom of the cowl so I built a small deflector
in the top to keep the hot air from hitting the gascolator directly.
Modify for your needs depending on the cowl opening size or
shape.
To use, just slide the duct under the airplane beneath the cowl
opening and plug in the heater. I usually place a blanket over
the cowl and cover the air inlet holes in the front to contain
the heat. There is VERY LITTLE heat loss in the duct so you
get the full benifit of the 1500W's in the engine compartment.
On one occassion when the temp in the hangar was 30*F, I was
able to bring the entire engine compartment on the Tripacer up
to 80*F, as measured by the oil temp guage, in 50 minutes on
the clock. That ment my cylinders and everything under the
cowl was ready for a safe start. If your battery is under the cowl,
even better. If you know you need to add a quart of oil before
flight and it's been setting in the hangar also, place it under
the cowl somewhere (top of cylinders) and it will be warmed
also during the heating process. I've even used the heater to
preheat the oil for an oil change and had all 6 quarts of the
replacement oil under the cowl and nice and warm for a
fast pour.
Refinements: For the health of the engine you don't want to
cycle the temp in the engine compartment (hot, cold, hot,
cold, etc.) but I suppose you could leave the heater in place
on a low setting and keep the engine always warm. Another
though I had but never bothered with was to plug the heater
into a thermostat control located under the cowl and let
the heater cycle and keep the temp constant under the
cowl. It would be ready to fly when you get to the hangar.
If you want or need a picture, e-mail me directly at
fles...@midwest.net
and I see about getting you one.
Try it! You'll never go back to a heating pad or dipstick, at least
at your home base.
Larry Flesner
