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  #11  
Old 12-12-2008, 05:46 PM
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Quote:
Originally Posted by Mark II
Here's a good site for data (photos) for the Sandhawk.

Also, I got a truly amazing amount of information (including the background info I posted before) from the NARTS Sandhawk Scale Pack, written by Matt Steele and Craig Beyers.

Mark \\.

The NARTS scale pak says the red color is close to "lusterless red" FS # 31302 (Federal Standard color) which would look like this according to a website I found when I googled FS-595. Found this site too, which is pretty interesting.
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  #12  
Old 12-12-2008, 09:05 PM
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Originally Posted by rocketguy101
The NARTS scale pak says the red color is close to "lusterless red" FS # 31302 (Federal Standard color) which would look like this according to a website I found when I googled FS-595. Found this site too, which is pretty interesting.

Yeah, I saw that in my scale pack, too, but I didn't think to do a web search to find out what that color actually was. The main message that I got from the scale pack was what I had previously stated, along with the practical advice that if you are entering your Sandhawk in a scale competition, make sure that your paint color matches the color in the photo that you include in your documentation pack, whatever that shade happens to be!

What I read the scale pack to say was that there is a bit of leeway regarding what is acceptable as an accurate shade of red for the Sandhawk.

The reason that I like Krylon Red-Orange Fluorescent so much was because I used it on the only other Sandhawk that I have built so far, the ASP Micro Sandhawk, and I liked the way it came out. To my eyes, anyway, it seems to match up pretty well with the swatch of FS 31302 shown on that website. (Of course, since my model is a micro, there isn't a lot of surface area on it, and the total amount of painted surface area can affect how well a particular paint color plays.) Also remember that just because we can all view the same reference color swatch on the web, it doesn't mean that we all see the same color. Different brands of computer monitors, differences in settings on individual monitors, differences in web browsers and even differences in operating systems can all lead to greater or lesser variations in the way that each person sees that reference color. These differences may not be very great, but they will occur.

Anyway, I'm a bit open-minded on this issue, especially if we are not talking about a scale contest entry. Probably any fiery red-orange color will work. I'll make up swatches of Krylon ROF and Duplicolor Radiant Fire and post photos of them to show if either one looks like a suitable color to anyone else.

Mark \\.
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  #13  
Old 12-13-2008, 09:51 AM
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Originally Posted by Mark II
Now here is where I am looking for some help. One of the things that is really hanging me up on my scratch-build is trying to visualize what those fin brackets look like in 3 dimensions. I have seen some good line drawings of them, and there is a very excellent one in my scale pack, but I am still a bit mystified regarding what parts along the brackets' outer faces (where the bolt heads are) curve in, and what parts curve out (if any). I am going to need to fabricate these brackets, and even though my model will be a sport scale, I would like to get details such as these at least grossly correct. Does any one have any idea, or, better yet, could anyone post a photo, taken at an oblique angle, of a correctly detailed fin bracket?

Mark \\.

Here is my take, using SolidWorks, from the NARTS Pak drawings. A couple details are missing, so this may not be 100% It appears from the NARTS drawing that the shroud is split into two 180 degree segment?!? I am showing it as a single piece. Also I had a tough time getting the leading edge taper on the fin modeled--I may play with it some more.

edit: the first view of the fin assy is the "front" and the second is the "right", showing the different bolt patterns at the top and bottom of the shroud. there are 3 bolts between the fins on two sides, and 4 bolts on the others.
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  #14  
Old 12-14-2008, 01:54 AM
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Quote:
Originally Posted by rocketguy101
Here is my take, using SolidWorks, from the NARTS Pak drawings. A couple details are missing, so this may not be 100% It appears from the NARTS drawing that the shroud is split into two 180 degree segment?!? I am showing it as a single piece. Also I had a tough time getting the leading edge taper on the fin modeled--I may play with it some more.

edit: the first view of the fin assy is the "front" and the second is the "right", showing the different bolt patterns at the top and bottom of the shroud. there are 3 bolts between the fins on two sides, and 4 bolts on the others.

Thanks a million, Dave! Your drawings have finally cleared up that mystery for me!

To answer your question about the fin shroud: yes, it consisted of two halves. My computer drafting skills are not nearly as good as yours; when I took drafting in high school, it was done on a piece of paper mounted on a board, and was accomplished with the aid of a T-square, a compass, a protractor, a pair of triangles, 2 or 3 lead holders, a lead pointer and a gum eraser! Anyway, I'll try to make a simple drawing in GIMP to illustrate how the two halves are laid out. But if you were to peel them off the Sandhawk and laid them out flat, next to each other, the pattern would be:

|-+--+--Fin-+-+-+-Fin--+--+-||-+--+--Fin-+-+-+-Fin--+--+-|







|-+--+--Fin-+-+-+-Fin--+--+-||-+--+--Fin-+-+-+-Fin--+--+-|


The "+" 's are the bolts
The "-" 's are just placeholders in the diagram
The double line "||" in the middle of each row in the diagram represents the space between the two half-shrouds.

The space between the two fins on each shroud has a 3-bolt pattern. The space between each of the fins and the edge of the shroud has a 2-bolt pattern. When the two shrouds are wrapped around the rocket, the 2-bolt pattern on the outside edge of one shroud adjoins the 2-bolt pattern on the outside edge of the other shroud, resulting in a 4-bolt pattern between pairs of fins on opposite sides of the rocket. Get it?

Mark \\.
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  #15  
Old 12-14-2008, 07:16 AM
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Like So? Now that I have taken a close look at my Estes Sandhawk, I see the split line -- I thought that was part of the plastic molding process.

The NARTs drawing makes it appear the shoud wall thickness goes from about 3" under the fins (basing on the length callout of the Heli-coils) to (I am guessing) about 1" at the ends. This is based on the section views showing the bolt patterns. I modeled it that way which is why it may look a little different than the earlier post.

Yeah, I spent plenty of time with paper, T-square, triangles, etc. When I first went to work ('79) we had tilt-table drafting boards with those drafting machines -- a big arm with swivels and a head that had two rulers attached at 90 degrees that could pivot to draw angles. I thought I was hot stuff with an electric eraser! We started using CAD on a mainframe system (2D) in the mid 80s. I mainly use CAD to draw models for finite element analyis or CFD work.
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  #16  
Old 12-14-2008, 07:23 AM
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Originally Posted by Mark II
.......when I took drafting in high school, it was done on a piece of paper mounted on a board, and was accomplished with the aid of a T-square, a compass, a protractor, a pair of triangles, 2 or 3 lead holders, a lead pointer and a gum eraser!.....

Oh...and don't forget the scum bag.....
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  #17  
Old 12-14-2008, 01:40 PM
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Originally Posted by barone
Oh...and don't forget the scum bag.....



Mark \\.
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  #18  
Old 12-14-2008, 02:48 PM
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Quote:
Originally Posted by rocketguy101
Like So? Now that I have taken a close look at my Estes Sandhawk, I see the split line -- I thought that was part of the plastic molding process.

Yup - you got it.

Quote:
The NARTs drawing makes it appear the shoud wall thickness goes from about 3" under the fins (basing on the length callout of the Heli-coils) to (I am guessing) about 1" at the ends. This is based on the section views showing the bolt patterns. I modeled it that way which is why it may look a little different than the earlier post.

I haven't actually looked at that issue yet, even though I have spent many hours studying the drawings in the scale pack. But I have mainly focused on adding surface details to my project, rather than trying to build a finely-scaled model from the inside out.

One other question: are those really "flats" on the fin can/shroud where the fins and brackets attach?

Quote:
Yeah, I spent plenty of time with paper, T-square, triangles, etc. When I first went to work ('79) we had tilt-table drafting boards with those drafting machines -- a big arm with swivels and a head that had two rulers attached at 90 degrees that could pivot to draw angles. I thought I was hot stuff with an electric eraser! We started using CAD on a mainframe system (2D) in the mid 80s. I mainly use CAD to draw models for finite element analyis or CFD work.

Part of me really likes the idea of CAD, even though I have never had the opportunity to try designing with it. I'm certainly no Luddite. But another part of me feels incredibly limited and awkward when I try to draw with a mouse. I just want to get my hands on the drawing, and manipulate real lines on real media, rather than moving pixels around on a screen. About 5 years ago, I actually went out and bought a drawing board, a T-square, triangles, leads, lead holders, a lead pointer, a compass, two scales and a French curve just so that I could work out design and construction issues with my rockets. I had not touched any of that stuff since the end of 9th grade, back in 1968! I just wish I could still remember some of the stuff that I knew from back then, like how to draw an isometric projection using just those tools. I have never used a real CAD program; I have done most of my digital drawing in GIMP.

Mark \\.
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  #19  
Old 12-14-2008, 03:36 PM
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Quote:
Originally Posted by Mark II


Mark \\.


I think he means a cleaning pad
http://www.draftingsteals.com/catal...aning-pads.html
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  #20  
Old 12-14-2008, 03:42 PM
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Quote:
Originally Posted by Mark II
One other question: are those really "flats" on the fin can/shroud where the fins and brackets attach?Mark \\.


That is what it looks like to me. I think the fin brackets fit onto the flats, with the boss (the round "knob" sticking out of the bottom of the bracket) going into the center hole of the flat area. The slotted holes in the fin bracket allow for adjustment of the fin angle to either add spin or to make up for manufacturing tolerances. After all the bolts are tightened down the fin is good to go!
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