C9.25 not available in Carbon Fiber tube for ASGT goto?

Rod Mollise posted:

Maybe this could be a problem. But I've yet to hear of anybody sustaining tube
damage of this kind over the--what?--three plus years the scope's been around.
I really can't see a downside to the carbon fiber tube. 'Course, the jury is
out on how it will hold up over the long run...but I suspect "very well."

Good, I was worried because when I first tapped the side of the OTA, it seemed
a little on the thin side, reminding me a little of the thickness of the
spiral wound "rocket launcher" tube which Criterion used on its Dynamax 8's.
However, the finish of the tube is quite nice, and pushing on the 9.25's tube
did not result in any visible deformation, so hopefully, the carbon fiber is
more than strong enough. I just worry about stupid accidents, like one at NSP
a few years ago. We warned a guy about the strength of the winds in
thunderstorms, but he still left his LX200 out on its tripod under a Desert
Storm cover as one of our famous 80mph gust fronts approached. It got blown
over and the tube was horribly dented. I may be buying this review model, as
overall, I am impressed by the NexStar 9.25GPS. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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"Jan Owen" wrote in message
news:_6VZb.9732$4K3.8220@fed1read06...
--
To reply, remove the "z" if one appears in my address
"Roger Hamlett" wrote in message
...

"David Knisely" wrote in message
...
Orion wrote:

Say it ain't so...
So far, the only solution I've found is to order the OTA and GT-5
Goto
mount
separately.
Why would Celestron make such a choice?
Considering how durable Carbon Fiber is compared to Aluminum tubes,
for
~$100 more, it seems nuts not to go with CF.
Any word on this?

The NexStar 9.25GPS that I am currently reviewing has a Carbon-fiber
tube.
I
worry about a sharp object hard impact which, on an aluminum tube,
would
only
dent things and remove some paint, but with a Carbon fiber tube, might
actually punch a hole in things. If I had been Celestron, the
aluminum
tube
would have been my choice, despite the mechanical considerations.
Clear
skies
to you.
If you think you are going to punch a hole in the CF tube, with any
force
that you are likely to meet, think again. I have tried the experiment of
shooting a rifle bullet, at a piece of laminate with a similar thickness
to
the tube used on the Nexstar scope. 0.22, removed some of the resin on
the
outer layer, but left no detectable mark on the back. 0.303, left a
slight
dent on the inside, that could be pushed out, and recoated with resin.
The
bullet did not go through in either case...

Best Wishes


I have some H110 .44 magnum reloads that'll have a little more impact than
that, if you'd like to try them on your Celestron...

Yikes! Smack me around if you wish. That was decidedly off topic. But
then so was your post...
Fortunately carbon fibre sheet and tubes are available for other places than
the scope itself, so testing doesn't have to be done on the 'real' object.
Given David's worries about the durability, it seemed entirely 'on topic' to
point out just how strong the tubes are. I tested it, because I have an
aeroplane, that has several parts made of this material, in a similar 'thin'
gauge to the tube, and I found myself wondering what would happen if (for
instance) a bird-strike took place on the leading edge of the wing.
Initially
I experimented with the 'Mk1 hammer'. It was only after this bounced off,
that I went into 'range testing'... I was very impressed by the overall
strength.
Basically at low forces the material deforms a little without any long term
damage. This was what happened using a hammer. Try harder, and it deforms,
and the laminate 'seperates', but the cloth remains intact. This is easy
to repair with epoxy resin. To damage the tube as badly as David is
thinking about, the optics would have been smashed long ago. An aluminium
tube like that used on the other scopes, wouldn't even stop the smallest
bullet I tried.
If you try the experiment of cutting the material, you get a very good
idea of just how tough it is.
That it stopped the 0.22, was 'pleasing'. That it stopped the .303, was
'suprising'.

Best Wishes

"Jan Owen" wrote in message
news:_6VZb.9732$4K3.8220@fed1read06...
--
To reply, remove the "z" if one appears in my address
"Roger Hamlett" wrote in message
...

"David Knisely" wrote in message
...
Orion wrote:

Say it ain't so...
So far, the only solution I've found is to order the OTA and GT-5
Goto
mount
separately.
Why would Celestron make such a choice?
Considering how durable Carbon Fiber is compared to Aluminum tubes,
for
~$100 more, it seems nuts not to go with CF.
Any word on this?

The NexStar 9.25GPS that I am currently reviewing has a Carbon-fiber
tube.
I
worry about a sharp object hard impact which, on an aluminum tube,
would
only
dent things and remove some paint, but with a Carbon fiber tube, might
actually punch a hole in things. If I had been Celestron, the
aluminum
tube
would have been my choice, despite the mechanical considerations.
Clear
skies
to you.
If you think you are going to punch a hole in the CF tube, with any
force
that you are likely to meet, think again. I have tried the experiment of
shooting a rifle bullet, at a piece of laminate with a similar thickness
to
the tube used on the Nexstar scope. 0.22, removed some of the resin on
the
outer layer, but left no detectable mark on the back. 0.303, left a
slight
dent on the inside, that could be pushed out, and recoated with resin.
The
bullet did not go through in either case...

Best Wishes


I have some H110 .44 magnum reloads that'll have a little more impact than
that, if you'd like to try them on your Celestron...

Yikes! Smack me around if you wish. That was decidedly off topic. But
then so was your post...
Fortunately carbon fibre sheet and tubes are available for other places than
the scope itself, so testing doesn't have to be done on the 'real' object.
Given David's worries about the durability, it seemed entirely 'on topic' to
point out just how strong the tubes are. I tested it, because I have an
aeroplane, that has several parts made of this material, in a similar 'thin'
gauge to the tube, and I found myself wondering what would happen if (for
instance) a bird-strike took place on the leading edge of the wing.
Initially
I experimented with the 'Mk1 hammer'. It was only after this bounced off,
that I went into 'range testing'... I was very impressed by the overall
strength.
Basically at low forces the material deforms a little without any long term
damage. This was what happened using a hammer. Try harder, and it deforms,
and the laminate 'seperates', but the cloth remains intact. This is easy
to repair with epoxy resin. To damage the tube as badly as David is
thinking about, the optics would have been smashed long ago. An aluminium
tube like that used on the other scopes, wouldn't even stop the smallest
bullet I tried.
If you try the experiment of cutting the material, you get a very good
idea of just how tough it is.
That it stopped the 0.22, was 'pleasing'. That it stopped the .303, was
'suprising'.

Best Wishes

Roger Hamlett wrote:

If you think you are going to punch a hole in the CF tube, with any force
that you are likely to meet, think again. I have tried the experiment of
shooting a rifle bullet, at a piece of laminate with a similar thickness to
the tube used on the Nexstar scope. 0.22, removed some of the resin on the
outer layer, but left no detectable mark on the back. 0.303, left a slight
dent on the inside, that could be pushed out, and recoated with resin. The
bullet did not go through in either case...

Best Wishes

That's good news for observers in Central Park. :-)


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Roger Hamlett wrote:

If you think you are going to punch a hole in the CF tube, with any force
that you are likely to meet, think again. I have tried the experiment of
shooting a rifle bullet, at a piece of laminate with a similar thickness to
the tube used on the Nexstar scope. 0.22, removed some of the resin on the
outer layer, but left no detectable mark on the back. 0.303, left a slight
dent on the inside, that could be pushed out, and recoated with resin. The
bullet did not go through in either case...

Best Wishes

That's good news for observers in Central Park. :-)


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Extremely heavy in the larger sizes, thats the reputation.

Great for the observatory, where one has a permanent site, a heavy mount on a
pier, etc., but most of us are transporting a portable scope to a remote
location.

jt

Martin,
Parks Optical use fibreglass tubes. http://parksoptical.com/tmc.htm
Dave

"Martin R. Howell" wrote in message
link.net...
In the ATM classic "Standard Handbook for Telescope Making"), fiberglass
is
said to make an excellent tube. Complete instructions are given on how to
make your own.

I can't see a downside to a fiberglass tube. Strong and very lightweight
with excellent thermal properties. . .why aren't commercial scopes being
offered with this tube? Are there suppliers for them?


Martin
Remove "ilikestars" from email address

Extremely heavy in the larger sizes, thats the reputation.

Great for the observatory, where one has a permanent site, a heavy mount on a
pier, etc., but most of us are transporting a portable scope to a remote
location.

jt

Martin,
Parks Optical use fibreglass tubes. http://parksoptical.com/tmc.htm
Dave

"Martin R. Howell" wrote in message
link.net...
In the ATM classic "Standard Handbook for Telescope Making"), fiberglass
is
said to make an excellent tube. Complete instructions are given on how to
make your own.

I can't see a downside to a fiberglass tube. Strong and very lightweight
with excellent thermal properties. . .why aren't commercial scopes being
offered with this tube? Are there suppliers for them?


Martin
Remove "ilikestars" from email address

"Orion" wrote in message ...
Say it ain't so...
So far, the only solution I've found is to order the OTA and GT-5 Goto mount
separately.
Why would Celestron make such a choice?
Considering how durable Carbon Fiber is compared to Aluminum tubes, for
~$100 more, it seems nuts not to go with CF.

Yes, it's amazing how many SCTs are suffering from premature aluminum
tube decomposition!
Uhhh, does the miltary fire rockets out of the carbon tube?
-Rich

"Uhhh, does the military fire rockets out of the carbon tube? "
I don't know. Seems to me CF would make a great mortar tube, especially if
you're the poor grunt that has to march 20 miles with it strapped to your
back.
"suffering from premature aluminum tube decomposition!"
Unless you are refering to rust, I never heard of that problem.
Other than having the advantage of a cheaper price, I have heard of no other
advantages Aluminum tubes have over CF,
certainly not in the thermal or strength categories.
Orion


"Richard" wrote in message
om...
"Orion" wrote in message
...
Say it ain't so...
So far, the only solution I've found is to order the OTA and GT-5 Goto
mount
separately.
Why would Celestron make such a choice?
Considering how durable Carbon Fiber is compared to Aluminum tubes, for
~$100 more, it seems nuts not to go with CF.

Yes, it's amazing how many SCTs are suffering from premature aluminum
tube decomposition!
Uhhh, does the miltary fire rockets out of the carbon tube?
-Rich


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