12 inch travel dobson.

[sumerian]

A view months ago I have made this 12'' f-5 travel dobson. Specially made for an astro holiday at one of the darkest places on earth. The dimensions of the travel mode had to be small as possible because I want to take it as hand luggage in the plane.

The problem was the mirror, 12'' means that I had to design a very small construction. Only a small design means that you have to do some important considerations between strength, stability and size. It was a hard thinking but one moment I knew it. I knew how to design it. With this design the dimensions fit perfectly within the specified size of the hand luggage. Now the only problem can be the weight of the dobson. Most of the time 26,5 pounds is to much for hand luggage,...... but there are a few tricks at the check-in on the airport. Just don't show them your hand luggage.

This dobson is made of 12mm plywood, poplar. Very light but strong enough to carry the 12'' GSO mirror. The trusses are made of 12mm thick aluminum and I can split them in two parts. The mirror has a 9-points cell. The size of the Orion Optics secondary is 63mm. Travel mode dimensions are 6 x 14 x 16 inch.

My next project will be a 12'' f-4 dobson. Same design but more stability, stronger, better balance and just for sure, it may be normal baggage when they find it to heavy for hand luggage.

[sumerian]

Two more pics.

[starstalker]

amazing work!!! well done mate!

[Astro_Baby]

Wow ! Again - you do such amazing building.

[sumerian]

Thanks. Two more pics.

[FraserClarke]

Some very impressive 'scopes in these threads over the past week. A real triumph of form from function

Well done

[kris h]

Amazing it looks awesome

[star girl]

I have to agree - this looks fantastic! Good luck using it on your travels.

[LukeSkywatcher]

Good luck getting that beauty onboard the plane inside the cabin. I wouldnt allow baggage handlers to "put" it into the cargo hold.

[acey]

Beautiful piece of work. Have you thought of putting plans online?

Couple of questions: how did you decide on the radius of the altitude bearings (e.g. did you hang the tube to find the centre of gravity?), and are the "ealstic bands" attached to the primary cell a means of tension control/adjustment?

[sumerian]

Thank you.

My plans on-line? Sorry, I won't do that because I don't want that everybody can easily copy my telescope. That doesn't mean that I don't give any advice. Ask me anything and I will answer it. But not my plans.

Mostly when I have to decide the radius of the altitude bearings I put the OTA on a stick and find the balance point. Just another way than you describe. But not now. This time I knew how big the telescope box was going to be and the altitude bearings had to fit in the box. The bearings are not big enough for the right balance and that is why I use elastic bands. They can adjust for the precise balance. It works very good for me but the only problem was finding elastic bands with the right tension.

[Earl]

Very sexy looking !!

I have often wondered about the open design of these, I take it these can only be used in very dark sites?

[sumerian]

You can use this open design everywhere you want. Not only at dark sites. When I am watching there is a light shield on it and in the eyepiece tube I put a baffle to eliminate light from the side.

But,... our climate is a bigger problem. We have to deal with something else. Dew. And that is the weakest feature of an open design.

[cyclone]

awesome scope, well done