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Star Cruiser

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#1 CMacD

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Posted 25 October 2012 - 07:34 AM

Anyone living in southern Ontario can testify to the value of clear skies. Or should I say that after years of dealing with the frustration from the lack of clear skies that we come to appreciate other aspects of our hobby - like telescope making, or conversing over the internet on sites like Cloudy Nights :) After owning a backyard roll-off roof observatory for a number of years at our previous home I decided to go one step further and etch one out from the roof of our current dwelling. After proposing this idea here and later realizing the enormous nature and risk of that task I decided to go back to the drawing board and looked for another option. Out of the ashes arose the idea of the Star Cruiser. Chris Erickson came up with that name and since then it has kinda stuck.

Since visual observing has never been my forte, and I appreciate the idea of designing something from scratch a mobile robotic observatory seemed like the right mix of challenge and function for the ultimate destination where the skies are NOT cloudy all night. Since then (this past spring) I remain amazed at how long this project has taken compared to the previous roll-off roof observatory. And I have barely begun to deal with the aspects of remote control and automation!

Needless to say rather than to post a few comments or questions with regard to this project every now and then I thought it would make more sense to create a thread dedicated to this journey from start to finish. I just got through reading Carol's BYO thread and really appreciated how everything went together. So - here goes.

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#2 CMacD

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Posted 25 October 2012 - 07:37 AM

About a year ago an orange tube C14 went on sale locally. $1700 was a good price and the optics were good and it really needed a good home so... At this point I was still thinking of a rooftop observatory so I was on the lookout for a good equatorial mount - CGE, G11, or Titan preferably. But when the kibosh got put on the rooftop and a trailer was in the future a fork mount seemed like the best option: no meridian flip, compact design and there was one model that was built like a tank. In comes awesomelenny. He was looking to move into an AP1200 and I could pick up his 16" Meade LX200 GPS forks and base for a reasonable price. These units are really solid. They stand over 3 feet tall and are just about as wide with two 11 inch worm gears and weigh in close to 200 lbs. WOW! Thanks Len. After a few modifications the two look like they were made for one another. I don't have to worry about being under mounted any more.

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#3 CMacD

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Posted 25 October 2012 - 07:45 AM

Where do you get a trailer and how will the scope fit in it? Originally I was looking at a used 6x8 foot trailer and just modifing it until it worked. But I never really liked the idea of a flat roll-off roof that would be hanging off the end essentially doubling the length of the trailer and becoming a giant sail for the next gust of wind that popped up. It would be hard enough to keep a trailer sturdy without the added obstacle of a flapping roof. I could possibly isolate the trailer from the scope but ultimately decided that the roof would slope down to the ground and just wrap around the front of the trailer. That way the wind would have a much harder time getting under things and moving them. I had an old camper trailer frame just lying around that I used for hauling wood out of the bush so I was set to proceed.

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There was enough metal on the original frame that it wasn't necessary to purchase much additional steel other than a couple of pieces to use for a wedge. The local Metal Supermarket had a nice 1/4 inch piece of metal for that. After mounting the scope there was still enough of a wobble in the system to warrant a few more galvanized tubes to the front and back to stabilize the final platform so they went on and fortified things significantly. The only real movement now comes from the mount itself.


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Of course the trailer could not rest on its springs so we needed a way to lift it off the ground. The four drop leg trailer jacks also provide a way of polar aligning the trailer and were slightly modified to contain set screws (3/8 bolts) to lock the feet into position and remove any residual wobble from the legs. There is also a small foot welded onto the front of the trailer to provide 5 points of contact in total. The main angle of the wedge on the trailer is about 30 degrees from the horizontal. When the nose of the trailer is dropped the angle becomes 51 degrees from the ground which makes the optimal latitude 39 degrees (90 - 51). So Denver would require very little lift :) This makes for a fairly wide range of latitude given that the drop legs provide close to another foot and a half of rise either way. (I am currently at about 47 degrees and can get there no problem.)

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#4 CMacD

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Posted 25 October 2012 - 07:50 AM

On to the box and covering. At this point you may be wondering why I left the scope attached to the trailer. Well, first of all, that mount is a beast. Just the tube and mount weigh about 250 lbs and it took 4 men to lift the combination onto the trailer. Secondly, given the sloping roof and a desire for as small a trailer as possible it just seemed easiest for measurements sake.

The floor is made from 1/2 inch plywood screwed down every foot or so. The bottom sides are 3/4 inch ply ribbed, glued and screwed for stiffness. The top frame was made from 1 x 2 softwood and covered with 1/4 ply glued and screwed. There were a few small gaps here and there where the trailer tubes intersected so I got out a can of foam and filled them in to keep the dust out.

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Originally I was thinking of a fiberglass covering. After reading a few discussions on this site I have decided to wrap the trailer in unpainted aluminum. I am in the process of insulating the inside with pink board. That should help keep the daytime temperatures as low as possible which was a concern given that a hot climate is the ultimate destination. I have cut a fairly large hole in the floor of the nose for a filter and fan blowing in for positive air pressure. There will be 2 vents up high on the back for heat expulsion. The C14 has been modified with internal fans to actively equalize and the walls have been kept fairly low to encourage air flow around the telescope when the roof is down. Hopefully this will be sufficient for dealing with environmental factors. When the filter needs to be changed the nose cover just unlatches from the trailer and is fastened back again with three hand nobs (3/8 bolts).

So thats where I am at... More updates to follow.

#5 johne

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Posted 25 October 2012 - 08:01 AM

What an incredibly GREAT idea. :waytogo: :applause:

#6 csa/montana

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Posted 25 October 2012 - 09:30 AM

We really appreciate you posting the complete build as you progress, this is an awesome idea! Can't wait for you to get it operating!

Thanks for reading my lengthy build thread on my dobservatory!

Looking forward to future updates! :)

#7 roscoe

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Posted 25 October 2012 - 09:35 AM

What an incredibly GREAT idea. :waytogo: :applause:


I agree! All the way to your observing site, every other auto on the road will be trying to guess what's in the trailer! :bow:
Russ

#8 David Pavlich

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Posted 25 October 2012 - 09:49 AM

Geez...a little radar absorbing material and...

Really neat!!!

David

#9 CMacD

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Posted 25 October 2012 - 10:00 AM

Geez...a little radar absorbing material and...
David


LOL. Never thought of it that way before. I hope they let me across the border :p

#10 Mirzam

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Posted 25 October 2012 - 02:44 PM

Very original and cool!

Maybe you can turn the roof into a tent for sleeping/warmroom.

JimC

#11 StarWrangler

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Posted 25 October 2012 - 05:23 PM

Now that is thinking out of the box,

Great concept and great work.

Alan O.

#12 Starman27

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Posted 25 October 2012 - 06:29 PM

Excellent idea and follow through. Keep it coming. Definitely want to see it in action.

#13 CMacD

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Posted 25 October 2012 - 07:12 PM

The R5 insulation for the top is just about finished now. It probably would have been much easier to blow insulation into it but I don't own a van or a truck to drive it somewhere so I just cut the hard stuff and set it in. I still need to silicone around the edges to hold it in place but that won't take more than an hour or so. You can also see faint areas of orange where I blew in the crack filler insulation to the places that were just too hard to get at. The metal rail along the bottom of the cover is for attaching to the rolling slides that will ultimately hold it in place. More on that later.

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As I mentioned previously (I figured I should add a pic) the base of the box is ribbed for extra strength. You can see from this photo that the scope has easy access to the horizons given the extra low walls. I still have much work to do with the sides. I plan on trimming the orange sprayed foam up a bit to make it a tad neater and adding styrofoam insulation as well to keep the daytime temps as low as possible.

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I also mentioned earlier about the nose of the trailer being modular. Here is a picture of the nose removed. You can see the holes that line up on both sides for the air to travel. You can also see the rectangular hole that I have cut into the floor for mounting an air filter and a 12 volt fan or two. (I have visions of standing beside a border guard removing the front end to assure him that I am not smuggling arms into the country :) ) I also plan on insulating the nose cone. Hopefully the extra effort up front insulating things will be worth it! I forgot to mention another reason for the nose to be modular: Removing the scope. With the nose removed it is much easier to jump up on the trailer and remove the three Allen bolts that hold the forks down. The air holes are large enough to get a large pair of hands in there with a socket set.

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#14 CMacD

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Posted 25 October 2012 - 07:53 PM

Lee Valley is an awesome store. About 3 months ago I was agonizing over the issue of rolling the roof. "Normal" roll off roof designs are horizontal and the roof itself has no natural tendency to fall one direction or another. Not so with this design. The roof here definitely wants to fall forward. This is in addition to the fact that the roof is not all that heavy either. It probably weighs in at 50 lbs or so at the most. I also wanted to be able to image in fairly heavy winds. Not sure if this is a reasonable requirement but none the less I thought it would be nice. Hence the problem: How to keep the roof on track and from blowing away? I needed to captivate it some how for sure. But what could I use? Lee Valley to the rescue. They sell what they call Extra Heavy-Duty Slides. Serious slides with serious prices! I purchased a pair of 48 inch slides designed to carry upwards of 400 lbs that could attach right to the walls of the trailer and hold the roof solid. They are essentially like those found on your desk drawers but on steroids. When drawn back they are 48 inches long. When extended they become twice that length with 3 sections telescoping outwards.

You can see from the image below that these are no ordinary set of drawer slides.

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And in the next image you can see that they extend a good deal in front of the trailer itself. This was the specific factor that determined the ultimate length of the trailer's top. I still have to mount a motor mechanism to drive this puppy but being as how it is so light and captivated by such a nice set of slides I am not all that worried how that will work out. I ended up attaching a piece of solid maple to the plywood sides of the trailer for mounting the slides. Screwed and glued of course.

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#15 wky46

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Posted 25 October 2012 - 08:02 PM

That's ingenious!

#16 Glen A W

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Posted 25 October 2012 - 08:15 PM

Why are you making me so jealous?!

GW

#17 CMacD

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Posted 25 October 2012 - 08:18 PM

Why are you making me so jealous?!
GW


:cool: <Grin!>

#18 Tom and Beth

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Posted 26 October 2012 - 02:46 PM

I LOVE this concept! Any idea what effect bouncing on the road would do to either Collimination of the tracking gears?
Would putting some type of shock absorbers on the trailer axle help?

Hey, are those "Moon" hubcaps? :lol:

#19 Gastrol

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Posted 26 October 2012 - 02:54 PM

I've seen wood burning pizza ovens on trailers but this is something I've never seen before. The setup is perfect for outreach. Nice job so far!

#20 CMacD

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Posted 26 October 2012 - 03:04 PM

I LOVE this concept! Any idea what effect bouncing on the road would do to either Collimination of the tracking gears?
Would putting some type of shock absorbers on the trailer axle help?

Hey, are those "Moon" hubcaps? :lol:


I definitely need to support the mount for transport. That would be a lot of weight on the main RA bearing at that angle. Meade suggests that you disengage the RA drive for transport anyway. I will probably mount some type of metal contraptions on the braces under the scope and fasten them with bolts. The C-14 mirror can be locked up and I have upgraded the secondary holder to be fastar compatible so I plan to remove the secondary when I am hauling it. I was hoping that those measures would be enough while travelling.

"Moon hubcaps" LOL. Na - I will be upgrading the wheels and tires at some point next year. Princess Auto had a sale on the correct size earlier this spring but I waited too long and the sale ended before I got there.

#21 Lorence

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Posted 26 October 2012 - 05:27 PM

I definitely need to support the mount for transport. That would be a lot of weight on the main RA bearing at that angle. Meade suggests that you disengage the RA drive for transport anyway. I will probably mount some type of metal contraptions on the braces under the scope and fasten them with bolts. The C-14 mirror can be locked up and I have upgraded the secondary holder to be fastar compatible so I plan to remove the secondary when I am hauling it. I was hoping that those measures would be enough while travelling.


Here's a link to a word document. Some trailer suspension work you might find interesting.

http://xa.yimg.com/k... 03 Trailer.doc

#22 CMacD

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Posted 26 October 2012 - 09:43 PM

Here's a link to a word document. Some trailer suspension work you might find interesting.
http://xa.yimg.com/k... 03 Trailer.doc


Interesting. Thanks Lorence. It looks like keeping my telescope attached to the trailer solves a number of problems.

#23 Lorence

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Posted 27 October 2012 - 01:59 PM

It looks like keeping my telescope attached to the trailer solves a number of problems.


Keeping your telescope attached to the trailer is fine with me. If it were my telescope it would be separated from the trailer and lowered into some sort of foam rubber cradle for transportation.

There's going to be a lot of force on the RA shaft and bearings when you hit rough roads

#24 CMacD

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Posted 27 October 2012 - 06:25 PM

There's going to be a lot of force on the RA shaft and bearings when you hit rough roads


Well Lorence, I guess that's where the extra supports will help. By supporting the forks from underneath I intend to remove some of the severe oscillations that would otherwise occur if they were left free to swing about. Sure there will be unnatural forces at play - but hopefully I will be able to steer clear of the larger bumps on the roadway too. I intend to drive like I'm hauling horses if the roads get bumpy :)

#25 Glen A W

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Posted 27 October 2012 - 06:29 PM

Mostly it depends on your trailer suspension. WSome trailers are really made for heavy loads, and with light ones they bounce enough to almost leave the ground. I had one like that.

If you take the secondary out I doubt very much you will have trouble!

There was a rig like this in S&T about 40 years ago. It and yours both look great to me.

GW






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