NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Doug Royer's Artificial Horizon
From: Doug Royer
Date: 2005 Feb 25, 11:44 -0800
From: Doug Royer
Date: 2005 Feb 25, 11:44 -0800
Doug,
I haven't yet made one of the plexiglas artificial horizons you designed, but expect to. Any advice or experience you could pass along would be appreciated. One thing I'm concerned about is the problem of a base. How do you manage this? Another is that, with adjusting screws in the reflecting surface itself, I'm afraid I'd jiggle the horizon every time I touched one of the adjusting screws. Is this as much of a problem as I suppose?
Bruce
I haven't yet made one of the plexiglas artificial horizons you designed, but expect to. Any advice or experience you could pass along would be appreciated. One thing I'm concerned about is the problem of a base. How do you manage this? Another is that, with adjusting screws in the reflecting surface itself, I'm afraid I'd jiggle the horizon every time I touched one of the adjusting screws. Is this as much of a problem as I suppose?
Bruce
Bruce,
a little background on this 1st.
Remember last year when you and George gave me pointers on the 1st(square)one I
made? I took both of your inputs and made
a triangular A.H.
I was experimenting making glass A.H.s that were square
with 6-32 machine screw level adjusters.That configuration was extremely
difficult to level out.
The black glass surface was extremely
reflective.However,I found it wasn't very robust as I cracked the glass at some
point and the 3145 RTV didn't like to hold the glass to the aluminum
base.Scratch the glass and back to the drawing
board.
The black plexiglass is 5/16 inch thick and
triangular.It has 7 inchs/side with 1 stationary 6-32 screw in the left corner
and 2 level adjustment 6-32 in screws in the other corners.These are 2.5 in long
and the plexiglass is threaded so the screws allow direct leveling.The 2
liquid levels are positioned close to the edge and positioned on the top surface
of the A.H. on 2 axis.I used a watery plexiglass adhesive to bond the
levels to the plexiglass surface.The whole thing costs less then $ 20.00 to
make.
I found that if one leaves the paper on the bottom side
of the plexiglass for some reason there is no double
reflection.
Leveling is not really a problem.Kick the dirt clean of
clumps or pebbles where you are going to set up.Place the AH on the area
swept and screw 1st one and then the 2nd screw to adjust for level.This takes a
few minutes but is not really that painful to accomplish.Once the bubbles are
centered in each level leave it alone as it will be as level as you can get
it.
No problem in seeing the sun on the surface of the AH.
I tried it on some stars and Sirius,Capella,Rigal and Aldebaran are easy to
pick up.I found because of the weight,or lack thereof,of the AH that a wind can
actually move or cause the AH to become off level.Place it in as guarded a
spot(less windy)as can be had that still allows you to line up the bodies needed
to take some cuts.
This is a robust assembly.Care must be taken NOT to
scratch or mare the plexiglass reflective surface as it is softer than
glass.I take the screws out of the AH for transport and wrap it in a
chamois.God knows those evil tempered horses tried their best to damage as much
equipement as they could during the trek.The sextant and AH came through
with only minor blemishes.
All this said now, I used this in a desert
environment.Not much moisture in the air to cloud the heavens and "fuzz" out the
body's image.Also,there was NO excess ambient light from the surroundings.It's
very dark at night in the desert.
I mention this as most listmembers reside in more
humid/wetter climes and that may have an effect on the clearness of the
reflections of the AH.
