Headlights

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

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


That's what I'm using, Lou. Bought a set of aftermarket fog light at
Wal-Mart. I'll be attaching one to my nosewheel. If I don't see the
light at night, it'll be a clear signal that I need to extend the retracts.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

Ernest Christley wrote:

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


That's what I'm using, Lou. Bought a set of aftermarket fog light at
Wal-Mart. I'll be attaching one to my nosewheel. If I don't see the
light at night, it'll be a clear signal that I need to extend the retracts.



An audible warning would be the sound of the prop striking the ground.

Dan, U.S. Air Force, retired

I Would use one of the little "muffin fans" available from surplus
stores, electronic supply stores, etc. get a 2 or 3" fan and duct it
so that you get good cooling of the bulb--there are lots of light wt.
headlight assys. on the newer autos, and you can find a little peanut
sized halogens up to 100 watts--but you need good connections and
probably a glass lens (too hot for plastic in my opinion)---Jerry
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

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

Jackie Yoder had car headlights in his leading edge. The only
tricky thing was bending the lenses. We went to great lengths
describing building the oven he used to heat up the acrylic.

In article ,
Ron Natalie wrote:

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

Jackie Yoder had car headlights in his leading edge. The only
tricky thing was bending the lenses. We went to great lengths
describing building the oven he used to heat up the acrylic.


I made copies of both sides of the LE of the wing out of plywood, formed
an aluminum sheet between them and covered it with thin felt and used an
oven set at (350(?). -- whatever Rohm & Haas recommends. Works like a
charm!

"Ron Natalie" wrote

Jackie Yoder had car headlights in his leading edge. The only
tricky thing was bending the lenses. We went to great lengths
describing building the oven he used to heat up the acrylic.

Do you know if he had the area opened up to the rest of the surrounding wing
(for dissipating the heat), or had some airflow going to the area, or some
other trick to keep the wing and plexi cool?
--
Jim in NC

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?


Energy is conserved. All of the energy used by a light
becomes heat. The energy that does not become light,
becomes heat locally.

So if you can find the efficiency of the type of light you
are using, subtract that number from one and mulitply that
differance by the wattage for the light. That will tell you
how much heat is going to be dissipated by the light.

E.g:

q = (1 - e)P

That won't tell you the surface temperature of the light,
but it will give you a means of comparing different lights.

E.g. a 1000 watt light operating at 5% efficiency will
dissipate as much heat as a 500 watt light operating at
10% efficiency. If the first has about twice the surface
area of the second then as a first guess they will both
have about the same surface temperature if housed in
similar environments.

BTW, weren't halogen bulbs originally developed for aircraft
landing lights?

--

FF

I didn't realize there was a test involved. I thought I would just make
a mock up enclosure with a thermometer probe inside.
Lou

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
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