Re: AP1100, Berlebach Planet, mounting CP4

Roland Christen

Whether you put the 3rd leg pointing North or pointing South, the clearance of the other two legs will be about the same. In fact, you will have slightly more clearance for the telescopes when pointing at the zenith because the 1100 Dec axis hangs more northward of center. It is also the most stable condition for the mount with just counterweights attached.


-----Original Message-----
From: ap@... <ap@...>
Sent: Tue, May 18, 2021 10:54 am
Subject: Re: [ap-gto] AP1100, Berlebach Planet, mounting CP4

As a follow on question with a Berlebach planet.

I received the mounting ring from Berlebach, and it emphasized how large the base of the AP1100 will be in comparison to this tripod.

I do not plan to have more than about 45 pounds of OTA, and counterweights of course. 

Does anyone with a similar setup have any kind of idea where the center of gravity is for that kind of setup?  Specifically how far off center?  

I typically image with the legs retracted fully for stability, and legs at closest are 9.5" (between legs) and 17" (at a single leg) from center.  I prefer to image with the single leg south not north, this provides a LOT more clearance (at least on my MyT) near zenith to avoid leg crashes.  But when I looked at that 9.5" it made me worry, this is a larger mount and probably different CG.

I found the Dimension Calculator spreadsheet, clearly aimed at clearance not load.  But I think (emphasis on think) that the point in the first image labeled as offset B, represents the BALANCED CG, basically at the intersection with the DEC axis.  

But what I am worried about is the unbalanced CG -- the point at which I have loaded 50# or so of counterweights and have yet to attach the OTA.  I.e. the situation why everyone says "put the single leg under the counterweight shaft".  Which is good advice I hope to not have to take so I don't hit the legs with my imaging train.

This all works fine on the MyT, it is quite stable.  But worried -- am I in for a rude surprise with the larger AP1100 (with 45# load)?  Yes, this is easy to figure out once I get it -- but if I need a new tripod/pier I'd like to get it on order now.

Anyone know where the CG is going to land?   And yes, I realize it's latitude dependent (I'm at 26d) but any real world experience welcome.


Roland Christen

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