Opinions please - Light bridge versus Aluminium tube

[davidpretorius]

Ok,

I want to be able to transport my telescope easier. I do not believe I will be in a positions to go a c9.25 and a decent mount (I must do this bit properly), SOOOOO

Do I go a lightbridge and then adapt the cooling and dob driver systems to fit or fabricate a 4 piece aluminium tube (like birds) and then build a better dob base for the dob driver?

Light bridge owers, do they pack up quite small? I want to come to the mainland more often and would like to fly and send my baby in a pallet!

Thanks guys

[stringscope]

Hi David,

Are you prepared to consider a truss tube other than a Light bridge, or do you specifically want a LB? Given you have a set of 10" F5 optics, it shouldn't be too hard to fabricate some sort of truss tube design with the UTA nesting inside the mirror box to transport/storage.

Cheers,

[janoskiss]

Lightbridge still has a big bulky and heavy particle board base. I was going to suggest what Ian just posted, i.e. build your own truss dob. It will be a lot more portable than the lightbridge. "The Dobsonian Telescope" by Kriege and Berry has pretty much all you need to know. Roger and Anthony at Bintel Melbourne should be able to help out if you get stuck with something.

[davidpretorius]

Thanks guys.

My main worry and it is because of my ignorance, is that I want a portable planetary scope. I want to stay at the high mags i am currently at.

How do the trusses go for planetary compared to the standard one I have currently?

[stringscope]

As I understand it key issues are:

1. Paying attention to baffling opposite the focuser and around the primary mirror.
2. Avoidance of heat plumes (usually from the observers body) through the optical path. A cloth shroud assists with this.
3. Mirror cooling.
4. Collimation.

If you pay attention to to the above, a truss tube should be at least as good as a solid tube and from what I have seen is generally better due to improved control of tube currents and better mirror ventilation.

BTW, I have found it much easier to fit mirror boundary layer fans to a square mirror box as opposed to a round solid tube.

Cheers,

[davidpretorius]

thanks ian

[stringscope]

Some quick back of the envelope "speculation" re possible size weight for transport:

Mirror box with single ring UTA nested inside, 400mm cube.
Base (rocker box and ground board), 500mm diameter X 200mm high
Truss tubes (8), 25mm X 1m aluminium tube.

The above assumes the use of large altitude bearings, 450-500mm diameter.

Weight, mmmmmm, ignoring batteries and assuming plywood construction, about 20kg

Cheers,

[ballaratdragons]

Just a suggestion Davo, but what if you purchased another dob and left it over here on the Big Island with someone you can trust! Then you don't have to carry anything over the Seas except your EP's.

Like I said, just a suggestion

[Starkler]

If you're gonna go to the trouble of constructing a truss dob, why not buy the optics and make it a 12" ;)

This is how you do your boundary layer fans (http://www.cloudynights.com/ubbthreads/attachments/928115-BoundaryFans.jpg)to get a nice laminar flow and blowing out of the mirror box

[Merlin66]

I think your weight is optimistic. Having built a few in my time err on the heavy side! The main mirror will be about 12 - 15Kg and you'll need some balance weights with the design as proposed say 10 - 15 Kg as well. Then there's the top ring and mirror cell etc etc
If your looking for a couple of aluminium rings to make the side bearings I've got a couple of 24" aluminium pulleys which would be ideal. PM me for details.