Paul,   The nose bowl can be reduced in size and frontal area. Better over the nose and around
the nose view.I think maybe the rad. would work better because the exhaust would not affect the
rad. because it is remotely located. A cabin heater could be installed inline as well . A bit more
streamlined I would think.The interior of the tail is generally not used for much else. Heater
hose I think could be used.It wouldn't require as much packed around the engine. Alot of planning
is required if it is all under the hood.  ROGER from Atl.

Technically speaking frontal area is rarely around the front of the
airplane. It is defined as the maximum cross-sectional area of the
aircraft. In the case of many pushers it occurs about 2/3-rds of the way
towards the back.

If you park the airplane at night in front of a brick wall
and you shine a spot light on if from a distance located on the
longitudinally axis a shadow will appear on the brick wall. If you
count the bricks that are in the shadow and add up their total
area then that is the frontal area of the aircraft.

Making the nose sharper may actually increase the drag but usually
improves propellor efficiency on tractor airplanes. Generally speaking
it is a wash.

I think you will lose a lot of water flow and cooling if you use heater hose.
Even for short runs under the cowl.

Paul Lamar

 I not  sure I agree. Take (for example) a MURPHY MOOSE,a M14P radial engine would have more
drag,( wind resistance ) than a lycoming IO 540. Assuming the engine frontal would be larger also
in an airplane containing a rad., even tightly packed in, it seems that it would make for a better
setup all around. It takes alot of effort to pack too tightly, don't you think?? ROGER from Atl.

Apples and oranges. Old radials are intrinsically high drag compared
to a flat engine. Has more to do with the cooling air path than
anything else.

It depends on the airplane. An RV8 for example has a generous stock cowl
volume to work with. So too an RV6.  A Glass Star is another one with 
plenty of cowl volume. An RV3 or RV4 are another matter.

Some airplanes have plenty of stock cowl volume but it is mostly down
below the thrust line and they are more difficult to install a rotary
in. My KIS cruiser comes to mind.

A Lancair 320 or 360 is one of the more difficult ones. What kind
of airplane are you building?

Paul Lamar


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