Headlights

Lou wrote:

I'm in the middle of assembling my wings on a wooden airplane, any
reason I can't use hologen car headlights in the leading edge?
Lou

OK, I have read several of the responses. There is a lot of difference
in halogen running lights, the kind you mount on the bumper or on a
light bar on top of your truck, and halogen headlights. The running or
off-road lights are usually small and designed to stay cool by being
mounted out in the air. They get HOT and don't work well when mounted
inside enclosures...where they may melt the insulation off their own
wires.

Halogen headlights these days are, in many cases, a plastic unit with
built in reflector and lens. The halogen bulb plugs into the rear. The
size of the reflector/lens housing dissipates the heat very well and
lights left on for hours with the vehicle sitting still have no problems
with meltdown. If you choose to use a complete headlight from a salvage
yard there will really be no problems in that leading edge position.
Leave the headlamp and housing intact and add a curved, leading edge
shaped Plexiglas lens in front of it. The draw back may be the physical
size of the headlamp will be such that it will not fit in the space
between the spar and leading edge. Mounting it out towards the tip of
the wing may put it in a position where cutting a hole in the spar to
allow for enough setback would cause no structural problems.

If you go with one of the running light/fog light types you will need to
build a metal box around it (not sealed up...just sides, top and back
plates screwed or tack welded together to reflect the heat.) and maybe
add a blast tube from a wing root air intake source. A plexi leading
lens will have no problem handling the heat if the lamp itself is kept
back a few inches (4 to 6 or so) from the lens itself.
--
Bruce A. Frank
======================
Aircraft Projects
Fuel Tank Fabrication
For Homebuilt Aircraft, Antique Fuel Tank Repair
TIG, MIG & Oxy/Acet Welding & Brazing

Big aircraft like Gulfstreams etc route ram air to cool the enclosed
landing lights through a piccolo tube. Because you need forward speed
there is a time restriction using them on the ground. Taxi lights are
on the gear so they don't need to cool them

That makes sense, but I'm curious of 2 things. Do you need an exit for
the air?
Is there a screening material to keep bug from nesting while not in
use?
Lou

On 23 Aug 2005 19:17:01 -0700, "Lou" wrote:

That makes sense, but I'm curious of 2 things. Do you need an exit for
the air?
Is there a screening material to keep bug from nesting while not in
use?
Lou
yes and yes.

Like he said yes and yes.

Some aircraft have a vent hole on the LE. The tube makes a turn to
get rid of the rain etc then dumps into the LE and departs eventually
where the wing de-ice hot air goes. Others get the air from the
pnumatic system of the aircraft so it is already bug and water free
and cools on the ground. Kind of hard to do that on a recip though.