Have been following with interest the thread exploring ideas on how to
accelerate the achievement of thermal equilibirum between the LX200 and
the atmosphere.

Here's my (untried) idea:

I got to thinking about what was providing heat to the air within the SCT
volume.

I'd bet that most of the mass in an empty (excluding the mirrors and
corrector plate) SCT tube is in the black steel casing on the rear of the
OTA. So that's the largest "thermal mass" (specific heat of the metal
multiplied by the mass) in the tube and thus is the largest source of heat
within the SCT volume. And it is this part of the SCT tube needs to be
brought to thermal equilibrium with the atmosphere as rapidly as possible.

I can think of a couple of ways to do this (one cheap and one expensive),
many of you will come up with other (hopefully cheap) ways:

One cheap way: Accelerate convective and conductive cooling of the casing
by increasing the surface area that is exposed to the atmosphere. This
might be accomplished by (somehow) adding heat sinks around the
circumference and/or to the backside of the casing. If there's enough
room, it might even be possible to add heat sinks to the back side of the
primary mirror--which is probably the second largest thermal mass in the
OTA.

One expensive way: Attach several thermoelectric coolers to the casing ;~}

An aside: I understand that the LX200 7" MAK has some added weight in the
back of the OTA for balance purposes. If my hypothesis is correct, than
this scope should take significantly longer to reach thermal equilibrium
with the atmosphere than, say, an LX200 8" SCT. Does anyone know if this
is so?

Looking forward to further discussion....


Gene Mroz
-------------------------
There is something fascinating about science. One get such wholesale
returns of conjecture from such a trifling investment of fact." Mark Twain.
-------------------------

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