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Ultimate capacity yet portable mount: AP 2400GTO ?

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#1 dothead

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Posted 01 March 2011 - 03:39 PM

...as an intermediate mount between the 1200 (81 lbs) and the 3600 (205 lbs), something like a 130ish lbs Astro-Physics mount would be still transportable for a determined individual (RA-unit approx. 80 lbs as the heaviest part), and would handle loooong refractors, like an 8" f/20, or big & heavy imaging scopes, like the CDK 17 & 20.

Do you think there's a "gap" between the 1200 and the 3600 ?

Could Astro-Physics touch a market segment with a 130 lbs "2400GTO" mount ?


Regards,

Ralph

#2 LLEEGE

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Posted 01 March 2011 - 03:50 PM

NEAF is right around the corned. You never know what Roland will unveil. This topic was mentioned on the APUG but RC didn't have much to say on the matter. I wouldn't hold your breath.

#3 Peter in Reno

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Posted 01 March 2011 - 03:57 PM

I wouldn't exactly call AP1200 portable and now you want a portable AP2400? AP1200 has a huge carrying capacity of 140 pounds. What monster scope do you want to carry and call it portable?

Peter

#4 dothead

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Posted 01 March 2011 - 04:31 PM

Quote:

"What monster scope do you want to carry and call it portable?"

8" f/20 refractor, with a weight of approx. 50 lbs ("portable" for a single person).

50 lbs may sound "easy" for the 140 lbs - rated AP 1200, but because of the extremely long torque moment arm (OTA length is 14 feet (with dew cap), it will tax the 1200 severely.

Torque moment is identical for:

14 feet 50 lbs OTA
7 feet 100 lbs OTA
3.5 feet 200 lbs OTA (which is beyond the 1200's capacity)

Got my point ?


Regards,

Ralph

#5 M13 Observer

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Posted 01 March 2011 - 04:32 PM

...as an intermediate mount between the 1200 (81 lbs) and the 3600 (205 lbs), something like a 130ish lbs Astro-Physics mount would be still transportable for a determined individual (RA-unit approx. 80 lbs as the heaviest part), and would handle loooong refractors, like an 8" f/20, or big & heavy imaging scopes, like the CDK 17 & 20.

Do you think there's a "gap" between the 1200 and the 3600 ?

Could Astro-Physics touch a market segment with a 130 lbs "2400GTO" mount ?


Regards,

Ralph


Sounds like the solution to a problem which doesn't exist.

#6 skybsd

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Posted 01 March 2011 - 04:33 PM

Transportable? Even if one could find a way to modularize the mount into more portable components, you're still left with a 140lb scope to think about..,

I'd have thought that if one had the coin for a CDK20, its reasonable to think that one would already have been looking at the el Capitan to begin with :smirk:

Regards,

skybsd

#7 dothead

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Posted 01 March 2011 - 04:38 PM

M13, skybsd,

So what about that 8" f/20, 50 lbs refractor ?

The 140 lbs rating applies to short, compact scopes.

Example: I've seen a 30 lbs 6" f/17.5 D&G mounted on the AP 900 (rated for 70 lbs), and the owner remarked that the 900 was barely adequate in holding it stable enough. He suggested the 1200 would be more appropiate for that 30 lbs refractor.


Regards,

Ralph

#8 skybsd

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Posted 01 March 2011 - 04:51 PM

Hello,

The 140 lbs rating applies to short, compact scopes.


I think you misunderstand..,

The CDK20 (bare OTA) weighs 140lbs - even if you find a way to design your theoretical mount to be modular enough to have portable assembly components, you still have to find a way to manage carrying the CDK20.

Regards,

skybsd

#9 dothead

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Posted 01 March 2011 - 05:08 PM

skybsd,

yes, you're right - the CDK 20 was an ill-advised example.

But still, what about that 50 lbs, 8" f/20 (my next scope project) ?

Re portability of the mount: for this 6' 3", 240 lbs guy, 80 lbs (as the heaviest part) is still manageable.

(Germany is the country of beer. A beer crate with 20 0.5 liter bottles weighs in at 19.7 kg = 43.4 lbs. I find it a not too big effort to lift two full beer crates together on a 30"-high table - so I consider it feasible for myself to handle a 80 lbs RA-unit).


Cheers,

Ralph

#10 M13 Observer

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Posted 01 March 2011 - 05:11 PM

M13, skybsd,

So what about that 8" f/20, 50 lbs refractor ?

The 140 lbs rating applies to short, compact scopes.

Example: I've seen a 30 lbs 6" f/17.5 D&G mounted on the AP 900 (rated for 70 lbs), and the owner remarked that the 900 was barely adequate in holding it stable enough. He suggested the 1200 would be more appropiate for that 30 lbs refractor.


Regards,

Ralph


http://www.planewave...ge=1&id0=1&id=2

Done.

#11 dothead

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Posted 01 March 2011 - 05:41 PM

thanks for the link.

Yes, I've also considered the Planewave mount, but the single most heavy component is 96 lbs, which is just that little too much (compared to 80 lbs) which would make it non-transportable for me.

Another candidate I considered is the Mathis Instruments MI-500 mount ( link ), but again, 100 lbs for the polar cone component is those 20 lbs too heavy.

Same with the Knopf MK-70 mount (see Astrolumina): relatively inexpensive for it's capacity, extremely stable, but 220 lbs with two 110 lbs components - not manageable.

What make AP mounts so attractive is that they are designed for maximum strength and rigidity with minimum weight.
Mathis Instruments, Knopf, and I suspect also Planewave, didn't intend their mounts to be portable, so they did not minimize weight to achieve portability.

I therefore suspect that a 130 lbs AP2400 mount would exhibit the same strength and rigidity as the 200 lbs MI-500.


Well, maybe I should just pull the trigger and see how the AP1200 would handle the 8" f/20 refractor...


Ralph

#12 skybsd

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Posted 01 March 2011 - 05:45 PM

Well, maybe I should just pull the trigger and see how the AP1200 would handle the 8" f/20 refractor...


Just about the safest bet anyone can make these days :waytogo:

Regards,

skybsd

#13 Peter in Reno

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Posted 01 March 2011 - 05:49 PM

Have you e-mailed Astro-Physics and asked if your 14 feet long scope can be handled by AP1200? They will be more than happy to answer.

Peter

#14 dothead

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Posted 01 March 2011 - 05:53 PM

well, you're probably right.

Though this mount from German master engineer Manfred Mauz (technical chief of the mechanical department of Munich Observatory) is reported to have a phenomenal stability for it's weight class (88 lbs, two 44 lbs components).

Decisions, decisions...


Ralph

#15 dothead

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Posted 01 March 2011 - 05:57 PM

Not yet.

The 900 is rated for up to 180 mm f/8 refractors, the 1200 for up to 206 mm f/8, the 3600 for up to 12" f/12.

Though I suspect the 1200 could handle a 10" f/12, and I know that at 3RF, a 15" f/12 D&G is mounted on the AP3600.

Another possibility would be the Parallax HD200C (105 lbs, breaks in two components).


Regards,

Ralph

#16 Alph

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Posted 01 March 2011 - 06:58 PM

Paramount ME is your best bet. The most efficient mounting on Earth. It weighs 87 lbs and it lifts 150 lbs. It is right now on sale for $12,500. It is a steal for anyone from the euro zone.

#17 skybsd

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Posted 01 March 2011 - 07:21 PM

It is right now on sale for $12,500. It is a steal for anyone from the euro zone.


Errr., Nope, nope , and..., no :(

Regards,

skybsd

#18 dothead

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Posted 01 March 2011 - 07:39 PM

The question is, can we take the manufacturer's stated capacity as gospel ?
In the light that some are more conservative than others with their specs.

Don't want to stir a hornet's nest, but are there opinions if the Pm ME ("150lbs cap.") is as beefy as the AP1200 ("140lbs cap.) ?

As a purely visual guy, I don't like to use a labtop in the field (like the Pm ME requires).


Regards,

Ralph

#19 Peter in Reno

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Posted 01 March 2011 - 08:05 PM

Astro-Physics capacities are typically for imaging. So if you are a visual observer only, then you can easily increase the capacity to up to double their advertised rate. Ask Astro-Physics first.

Peter

#20 Alph

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Posted 01 March 2011 - 08:39 PM

It is right now on sale for $12,500. It is a steal for anyone from the euro zone.


Errr., Nope, nope , and..., no :(

Regards,

skybsd


Sure, but he does not have to use an european dealer.

#21 Keith Howlett

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Posted 01 March 2011 - 10:05 PM

The question is, can we take the manufacturer's stated capacity as gospel ?
In the light that some are more conservative than others with their specs.

Don't want to stir a hornet's nest, but are there opinions if the Pm ME ("150lbs cap.") is as beefy as the AP1200 ("140lbs cap.) ?

As a purely visual guy, I don't like to use a labtop in the field (like the Pm ME requires).


Regards,

Ralph


Hi Ralph,

You see quite a few 20 inch RCOS mounted on Paramounts and these weigh 163 lbs without cameras and accessories. I don't think I would get away with that on my AP1200 but I think it would cope with the advertised cat/cass type 140 lbs load. (It was loaded to this level by the previous owner with no ill effects.)

Cheers,

Keith

#22 skybsd

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Posted 02 March 2011 - 03:16 AM

It is right now on sale for $12,500. It is a steal for anyone from the euro zone.


Errr., Nope, nope , and..., no :(

Regards,

skybsd


Sure, but he does not have to use an european dealer.



Indeed - I don't disagree with you..,

But unless such a buyer is willing to be creative - they're stuck with SB's EU distributorship's pricing :)

Regards,

skybsd

#23 dothead

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Posted 02 March 2011 - 04:58 AM

Keith,

many thanks for your reply.

The question is how a mount will handle not a heavy, compact, but a "lightweight", but extremely long OTA.

While going lightweight with a long OTA (I'll use Carbon Fibre as material) sounds a good idea as far as portability of it is concerned, this also decreases the OTA's inertia against torque forces, like wind - talk about surface to mass ratio.

Guess I have to do real sound calculations to get a better idea of the matter - or better still, mount the 8" f/20 CFK refractor OTA on an AP1200 of someone else's first and see how the setup behaves...


Regards,

Ralph

#24 Keith Howlett

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Posted 02 March 2011 - 07:15 PM

Hi Ralph,

That's understood and it's a question for the good people at Astro-Physics. They are very helpful, it would be worth a phone call.

Cheers,

Keith

#25 Duncan Kitchin

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Posted 02 March 2011 - 11:10 PM

It is right now on sale for $12,500. It is a steal for anyone from the euro zone.


Errr., Nope, nope , and..., no :(

Regards,

skybsd


Sure, but he does not have to use an european dealer.


I'm not so sure about that - buying from outside of Europe and having it shipped can be expensive - particularly if customs stop the package in transit (becomes more likely with large packages) and demand the payment of 20% VAT...

Regards & Clear Skies
Duncan






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