Re: [ATM] wire spider ready!

["Mel Bartels" <mbartels@bbastrodesigns.com>]

>      I just saw that wire secondary Jan made from one of your designs
> and that is the way to go!  I also saw the wire frame telescope that
> won that price at the riverside contest and really like it.  although I
> wonder what the weight difference is bewteen aircraft cable and
> aluminum tubes ?  I seems to me the tubes would be lighter?


That's the engineering challenge.  If you build with the same thinking then
the weight will not be reduced much.

My 20 inch 0.5m scope mirror weighs 50 pounds 23 kilos

The entire rest of the mount including the oversized base ring weights 35
pounds 16 kilos

The goal is to get this 'rest of the mount' to weigh much less than the
primary, somewhere close to 1/2 of the primary weight.

Remember that telescopes functionally (well, actually any structure) can be
decomposed into compression and tension members.  The tension members are
eligible for wires and the compression members need only enough dimension
(weight, thickness of tube walls) to avoid collapse.

Mel Bartels


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