Posted 22 October 2004 - 11:55 PM
I am relatively new to astronomy (coming up on year now), but in many ways it just feels like something I've always known I'd get into but just didn't have the time to do so previously. A question posed by the wife as to whether or not we should get a telescope for our son has turned into a mild obsession for me (and I never do anything half way). I'm at least happy to report that the 9 year old son enjoys the nights with the astronomy club as well - particularly when he can point the "red dot" at things and nail them in the sight!
But here's my challenge: The wife and her best friend have purchased a camper-trailer and intend to travel the western U.S. next summer with the four kids. The husbands (that would include me) are to join them for a couple of weeks, likely in the Grand Titons... so naturally, I'm thinking, "I have got to bring a scope."
At present, I have a home-built (purchased) 10" f6 dob, lots of plywood, lots of sonotube, very stable and very wonderful but also awfully heavy and not very transportable. No way this thing is getting to the Grand Titons. Now Jack (my son) likes building stuff goo, so I'm thinking, hey, why not build a truss dob? I bought this scope primarily for the quality of its mirror - I've got a 10" Zambuto here, and a growing collection of quality eypieces, so I'm thinking it's absolutely worth the effort.
Now, I've got a table saw and have enjoyed construction projects in the past, am somewhat of a perfectionist, and would likely have a lot of fun with my son "helping out" here an there. My best friend is a machinest, and I'm sure would love make a contribution as well. So my question is, is it reasonable to think I could get this thing on a plane next summer? The mirror would need to be a carry-on in some fashion, a larger piece could could in the airline cargo-hold, and if necessary the girls could haul something that didn't take up a lot of space across country (poles?)
The positive by-product of all this would be a more light-weight telescope that'd be easy to transport in the car - though I wouldn't want to lose a whole lot of stability in the process - hand-tracking is hard enough as it is.
Let me know what you think, and if you have any recommended designs or ideas that would apply to my constraints.
Contemplating the possibilities, with respect to all who have gone before,
Posted 23 October 2004 - 08:02 AM
Is that your scope? I noticed the mirror had been refigured by John Hall. Mine just got done by John as well. I tried to e-mail the author of the report but it would not go thru.
Posted 23 October 2004 - 08:44 AM
Posted 23 October 2004 - 10:41 AM
Posted 23 October 2004 - 01:09 PM
Posted 23 October 2004 - 06:27 PM
Doug I think the challenge is not only to make the thing small and light, but also minimize the number of parts and keep set up to a minimum. You having a machinist friend may prove to be very helpful in the end. Good luck to you.
Posted 23 October 2004 - 07:13 PM
There are a lot of choices for a travel scope and they all have trade-offs. I choose a string scope for my travel scope.
I live in San Jose and occasionally bring this scope to Hogue Park if you want to see it in person.
Another option is to go with a traditional dob, but make the mirror box so that the UTA fits inside the mirror box for transport. You then end up with a single box plus poles for transport. The trade-off is that the mirror box ends up being bigger than it my otherwise be.
Here are some links to some examples
Travel scope #1
I almost made one like this
Another 10" travel scope
Portable 12.5" Funky 8" travel scope
Hope this helps.
Posted 24 October 2004 - 03:45 PM
Craig, that's a real beauty you've got there. Let me know next time you're planning to head to Hogue Park with it as I would love to see it in person!
Steve Vegos's "Another 10" travel scope" looks really promising as well. I'm really curious how he did the counterweighting to gain such a low profile so as to "comply as carry on luggage", and wondering if this would be at all possible to pull off at a longer f6.
Other stuff I've seen, for the benefit of others looking to get ideas:
Starbuckets designs: http://www.starbucke...telescopes.html
Regarding airline-ability, I'm gathering now it's either got to be small enough to be able to carry on key components, or it should fit in a pelican case to tolerate rough cargo-handling (though I don't think I'd ever feel comfortable seeing my mirror on the conveyer belt). I could easily have two sets of tubes though, one set for home & one set for the camper trailer, so at least that would help.
Hmmm. BEFORE the girls' camping trip, my goals had been (1) retain usability as my primary scope (2) compact for car travel and (2) fun (my design tinkering lead to a truss-tube design with a clipped-corner triange base, ornamental rockers and whimsical secondary cutouts While I'd still love to do this, I suspect it'd be too heavy and large for airline duty.
There are other ways to be fun that wouldn't involve as much weight, but I'm wondering if the compromises required to get in onto a plane would relegate it to "travel scope" status only - and I'd really prefer to keep this as my "primary" scope.
OK, 'nuf for now.
Posted 24 October 2004 - 06:04 PM
Posted 24 October 2004 - 06:20 PM
Preliminary design is the funnest part! My scope is based off of Albert Highe's design with my own modifications. Albert is more than willing to help you with design issues and is an email away.
Albert is very helpful. He lives in Northern CA so you can frequently see him at the local dark sites. At CalStar last week he had his latest scope made out of paper that was beautiful. It was a 12.5" scope which I believe he said weighed 46 lbs.
Michelle Stone who builds and sells Albert Highe designs is also quite often at the local dark sites and she is very willing to lend advice on scope building. So if you do decide to go with an Albert Highe design I would definitely talk to Michelle (she occasionally posts here as well).
Posted 24 October 2004 - 07:32 PM
Posted 26 October 2004 - 11:12 PM
(1) Easily portable, meaning e.z. to move outside the garage for quick viewing at night, able to fit into a single seat of a car, and able to be taken on flights with all optics in carry-on components.
(2) Very stable, suitable for use as a primary scope.
(3) Unique and Fun! I'd like this to be the scope the kids run up to at a public night just 'cuz of the way it looks.
OK, with all that in mind, and after perusing the wonderful web, I've started to settle on a design, and in fact have drafted a conceptual diagram, but am not quite set up yet to post it.
To describe it, from the bottom up:
With an f6 mirror, I want a really wide base and wider than typical connect points for the lower portion of the supports. I think something modeled after the low-profile & ultralight double-rings of Greg Babcock's "Ultralight" would be supurb, and could be made very wide and yet still be packed into a travel bag (provided the rocker arm supports are no more than a couple of inches high). Such a low-profile design would require additional weight or possibly springs - at 10", I wouldn't expect plain old lead weights to be that unreasonable, actually. If they have to be hand-held, I'd use scuba weights which are wrapped in plastic.
Having thus dispensed with the rocker box, in favor of stubby supports for the rockers, we'll need big rockers to help compensate. No problem - I love big rockers, think this is a great place for some really cool design work. I'm thinking 20" diameter. These can lie flat in the travel bag as well. To keep everything stable, I'll put a 2" tube between them at the furthest point from the mirror box.
For the mirror box itself, I couldn't help but notice the little box that StarMaster uses to transport the mirrors - and I'm thinking, hey, why not just use that as the mirror box? I'll jsut beef up the carrier box and attach it directly to the rocker arms. Dimensions 4" high by 14" wide and under 22" long - small enough for "carry on" even with a 5" "hat box" for the secondary on top. The extra width of 22" both increases the base for stability and would allow 3 1/2" holes to stuff counter-balance weights into.
The "hat box" would be a 5" piece of 14" sonotube into which the secondary would go (agreed, that will be a bit of a challenge, and require a light shroud, but that can go in the garment bag also). One end of the sonotube would have an 11 1/2" round cover which would also fit both the secondary itself and the primary mirror hole. The other end would be a flat panel which is removed to get out the secondary. the "hat box" itself would be attached to the mirror box as a light shround.
I'll go with a 6 truss-tube design, with 2 of the attachment points at the corners of the mirror boxes nearest the sky when aimed at the horizon, and the third smack in the middle of the 2" connector tube between the rockers (that'll be one of the tougher design aspect, I imagine).
Woo hoo! This is fun. Any suggestions on where to post pictures so as to be able to point at the URL? I'd like to post the conceptual diagram... I could bring my web-server back up, but that might take awhile...
Doug "I don't even know what questions to ask yet..."
Posted 26 October 2004 - 11:45 PM
Honestly, why carry the mirror? Pack it within an inch of it's life and don't worry about it. If you design the packaging as part of the overall design, you can do it in such a way that a gorilla would have to take it out of it's case and drop it in order to hurt it.
Looking forward to seeing the drawings.
Posted 27 October 2004 - 12:13 AM
Posted 27 October 2004 - 12:41 AM
Posted 27 October 2004 - 07:58 AM
Posted 27 October 2004 - 09:18 AM
Posted 27 October 2004 - 09:25 AM
...but blinking LEDs???
It was a joke...you said you wanted a scope that all the 10yo boys would flock to at star parties. Having boys of my own, I know how much they like blinking red lights! Actually, placing the battery in front of the mirror box and making it part of it will shift your CG to a more appropriate location as depicted in your initial drawing. This design is cool looking...I hope you take my comments as just food for thought.
Posted 27 October 2004 - 10:41 AM
...but blinking LEDs???
It was a joke...you said you wanted a scope that all the 10yo boys would flock to at star parties. Having boys of my own, I know how much they like blinking red lights!
Posted 27 October 2004 - 02:50 PM
Posted 27 October 2004 - 11:44 PM
Ok, here's the latest, a top down view of the Mirror box, working through some issues. Everything's centered again now, with the central tube still extending past the sides as I liked. All looks good except that I can see that the base for this is going to be too big around to fit in the garment bag. Aghh! OK, next rev, I'm going to pull int the sides by 1-2" and the rocker arm diameter by 2-4" to get to where the base could fit in the garmet bag. Hope there's still enough room for the weights!
One other thought about the weights - it ocurrs to me this scope will be pretty light without them. It'd be very easy just to put a duplicate set in the camper trailer, meaning I wouldn't have to lug them on the plane!
Posted 28 October 2004 - 04:09 PM
Way cool! I like the 3-pole Highe design myself for a mid-aperture scope. I built a 10" f/6 truss dob myself w/ 8 standard truss tubes (also with a Zambuto mirror - what the heck!). I'd avoid the 6-tube design simply because it forces you to have a larger mirror box to keep the trusses out of the light path.
I kind of like the hybrid approach also. Instead of reducing the number of truss tubes from 8 to 6, make a lightweight truss assembly. The truss tubes would come down and attach to a circular base ring which then attaches to the top of the mirror box. The truss assembly can be popped off in one piece. There's lots of nifty clamps and hardware out there which would make this solid and easy to disassemble. I hate playing around with truss tubes!
I had made my 10" dob using 0.75" diam. alum. tubes.
It was plenty strong enough.
Posted 28 October 2004 - 07:32 PM
I see what you mean about the light path. Looks borderline in my current drawing. Hmmm... thanks for pointing that out!
I'm curious - how far apart were the lower attachments points for your truss tubes? I've been concerned about having enough distance to support the secondary that sooo far away with an f6, i.e. truss tubes are based on triangle design, not parallelagrams.
Now the Highe design of course turns this all around, and I'm sure would make a fine narrow-base f6. I was leaning that direction for awhile, but then realized I actually want a fairly wide base for stability anyway (as wide as I can still figure out to get get packed on a plane, that is). I think the turning point was just falling in love with this idea of attaching rockers to a low-profile mirror case and setting it on a super low-profile base.
I'd been thinking about the ball & socket style truss connectors, ala Moonlight... I can see how a hybrid model would be really nice for short "club night" rides & quick setup though. One concern would be collapsability - I want to be able to keep an extra set of poles in the camper trailer, so I wouldn't have to fly with them. There wouldn't be room for a pre-build cage, but perhaps even that could be taken apart, too. Hmmm... lots to think about. Thanks!