What is an isostatic mount

[Kobayashi Maru]

Please forgive my ignorance but what is an isostatic mount?

I know what one looks like and I think I understand why they would be well balanced and easily panned...but what makes them isostatic?

- The counterweights ensure even balance in altitude

- The fork would help with torsional forces when panning

Is that it? If that is it wouldn't a T mount with a forked tiller also be isostatic?

 

 

[markse68]

I had to look it up. There was a Tuthill isostatic mount that seems to be a forked equatorial but instead of a tripod and wedge it uses longer legs on one side and incorporates the equatorial wedge into its structure. I guess it keeps the c of g central within the 3 legs rather than it being weighted to one side as it would be with a tripod and wedge. Which i guess would make it more stable. @Peter Drew probably knows a lot more

Mark

[Kobayashi Maru]

14 minutes ago, markse68 said:

I had to look it up. There was a Tuthill isostatic mount that seems to be a forked equatorial but instead of a tripod and wedge it uses longer legs on one side and incorporates the equatorial wedge into its structure. I guess it keeps the c of g central within the 3 legs rather than it being weighted to one side as it would be with a tripod and wedge. Which i guess would make it more stable. @Peter Drew probably knows a lot more

Mark

Yeah I saw that as well. 

Originally I saw the TSS Panther mount referred to as isostatic. https://trackthestars.com/tts-160-panther-telescope-mount/ . Someone on SGL made DIY solution with similar mechanics.

I think some other reversed fork mounts are also referred to as such.

 

[Peter Drew]

39 minutes ago, markse68 said:

I had to look it up. There was a Tuthill isostatic mount that seems to be a forked equatorial but instead of a tripod and wedge it uses longer legs on one side and incorporates the equatorial wedge into its structure. I guess it keeps the c of g central within the 3 legs rather than it being weighted to one side as it would be with a tripod and wedge. Which i guess would make it more stable. @Peter Drew probably knows a lot more

Mark

I don't think there is a lot more to know.  🙂  Mounts can be balanced nicely but still somewhat out of balance with their support pier or tripod.  To be considered isostatic the whole system needs to be in mechanical balance.  A Dobsonian mount satisfies this condition.

[Kobayashi Maru]

46 minutes ago, Peter Drew said:

I don't think there is a lot more to know.  🙂  Mounts can be balanced nicely but still somewhat out of balance with their support pier or tripod.  To be considered isostatic the whole system needs to be in mechanical balance.  A Dobsonian mount satisfies this condition.

Surely something in astronomy cant be as simple as you first expect! I'm going to need a lie down.

[Zermelo]

On 06/03/2023 at 21:52, Peter Drew said:

I don't think there is a lot more to know.  🙂

oooh, now there's a challenge

https://warwick.ac.uk/fac/sci/maths/people/staff/robert_mackay/isostaticmount8.pdf

[Peter Drew]

Of course!.   I should have said "one needs to know".     🙂