Telescope Reviews: Re: Thinking about a OTA upgrade to Carbob fibre.

Someone at IIS http://www.iceinspace.com.au/forum/showpost.php?p=503298&postcount=18 suggested using a Protostar BlackLite tube, said they were very pleased with their's that they used in the 10" f3.8 astrograph as their tube structure.

The OD for the 12" tube they have is 299mm , their wall thickness is 3.6mm , their tube mass = 27g/cm ==> a 1.27m tube will be 3.43kg (that's pretty good !!).
Their modulus of elasticity is given as 1400 PSI.

Being preflocked is a definite plus, that'll save some money as I'd have to buy another lot of self adhesive Protostar flocking material and go through that process again once my CF tube is made , holed and drilled.

Has anyone used a Protostar BlackLite tube for their stand alone tube for a 10in or bigger newtonian here and checked how well it holds collimation without an outer structural tube to reinforce it ?

Proposal : Hybrid CF overlayed BlackLite tube.

Buy a Protostar BlackLite tube
add a layer of 3k unilateral CF (long wise)
then a layer of 3k unilateral CF wrapped with fibres rounding around the tube)
finish off with a later of either plain or 2x2 twill weave 3k CF
with aim of stiffening up the structure of the tube ....

Pros :
**** no need to make a disposable mandrel , the CF will be permanently bonded to the BlackLite tube.
**** mo need to buy another roll of ProtoStar SA Flocking and do the flocking process again.
**** the tube will be significantly lighter than my existing 300mm NB UPVC stormwater pipe offcut as the BlackLite tube weighs 3.4kg and the added 3 layers of epoxy bonded CF cloth will add 1.3kg = 4.7kg for the new tube (UPVC is 11kg).

Cons.
**** my old AstroSystems spider will not fit the BlackLite tube , not a big deal , spiders are cheap.
**** will have to check my tube rings are OK with a 300mm OD tube ,designed for a 316mm OD tube , may need to modify them, no big deal.
**** unshore how well epoxy resin will bond with the outside surface of a BlackLite Tube ? needs to be a good permanent bond.
**** cost of shipping a tube from Protostar to Australia may be prohibitively expensive and a proposal killer.
**** will have redo my OTA design calcs based on the focusor being 8mm closer the OTA centreline (well just shift the location of the mirror cell back 8mm) , no big deal.

Question : anyone tried a hybidised CF coated Protostar BlackLite large diam tube ?

Edited by Ian Robinson (10/07/09 01:48 AM)

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