Jay's "Prometheus" -- Take 2

[Tau Zero]

From the "Jay's in the air (http://forums.rocketshoppe.com/showpost.php?p=8227&postcount=10)" thread, we bring you the following rerun: Prometheus on the pad (http://forums.rocketshoppe.com/attachment.php?attachmentid=2698) (01 June 2006).


And "What's in YOUR build queue": I cut out fins for Prometheus Prototypes II and III tonight/this morning. It looks like #3 is headed southwest.Tonight I stack-sanded 6 fins for 2 Prometheii (sp.?). I ran into a little difficulty with the balsa splitting at the "bottom" corner of the root edge off of one of them, so I'll have to post a pic later this week.

Next, the computer label paper and CA application, followed by sanding the edges. It's a good thing I was farsighted enough to buy enough parts for 3 copies of this design. Heck, I've even got the parts for one already Ziploc-ed! --I'll have to replace that 24" elastic cord with one that's 3 feet long, though. :o :p


Cheers,

[CPMcGraw]

...Tonight I stack-sanded 6 fins for 2 Prometheii (sp.?). I ran into a little difficulty with the balsa splitting at the "bottom" corner of the root edge off of one of them, so I'll have to post a pic later this week.

Next, the computer label paper and CA application, followed by sanding the edges...

Jay,

Try this trick next time you hand-cut those fins...

Lay out a set of fin outlines onto the label sheet the same way they would line up on the sheet of balsa. Print them, then peel and stick a full strip of fins to the balsa sheet first. You only need to print one set of patterns; use a blank label on the flip side. Now, when you cut those fins, you cut through the paper and the balsa at the same time, and the label sheet will reinforce those corners from both sides.

When you start sanding the edges, the paper will fray and feather into the round-over, but not terribly much. When you finally hit it with Kilz, or whatever primer you use, those edges will blend and disappear.

[Tau Zero]

Lay out a set of fin outlines onto the label sheet the same way they would line up on the sheet of balsa. Print them, then peel and stick a full strip of fins to the balsa sheet first. You only need to print one set of patterns; use a blank label on the flip side. Now, when you cut those fins, you cut through the paper and the balsa at the same time, and the label sheet will reinforce those corners from both sides.I did that with my 100% and 136% Estes Wolverine clones, and it seemed to work nicely. On the first "remake" of the Micron fins, however, it didn't go so well. (Sorry about the horribly blurry picture, but maybe you can make out how uneven the edges are.) So I decided to stack-sand the next set *before* applying the computer label paper.


When you start sanding the edges, the paper will fray and feather into the round-over, but not terribly much. When you finally hit it with Kilz, or whatever primer you use, those edges will blend and disappear.The curved outline for the fins on my "abbreviated" Excelsior Love Bugs (http://forums.rocketshoppe.com/attachment.php?attachmentid=3091) didn't cut very uniformly, so that's when I started doing the stack-sanding *first.* (Sure, it means having to cut the "sticky" side of the label paper once for each side, but at least I can control the Previously Uncertain Variables.)

Additionally, my Middle-Aged Shaky Camera Button Finger made me have to draw in the details of cutting the out the Prometheus fin to avoid the aforementioned "Balsa Chipping."


Thanks, and cheers,

[CPMcGraw]

...make out how uneven the edges are...

Yea, I get that myself. My fingers holding the #1 handle just can't compare with Carl's laser finger...:rolleyes:

Now there's a BOND-ish (or POWERS-ish) sounding moment...

LASERFINGER


The curved outline for the fins on my "abbreviated" Excelsior Love Bugs didn't cut very uniformly, so that's when I started doing the stack-sanding *first.*

Alternately, apply one label, then stack the fin blanks together and sand the stack to the outline. Lots of sanding dust, but the stack comes out crisp...

The cutting direction image is handy. I never actually thought about the way I cut my sheets, but that does make sense. The most fragile area gets cut inbound instead of outbound. I'll have to try that next time.

[Tau Zero]

The cutting direction image is handy. I never actually thought about the way I cut my sheets, but that does make sense. The most fragile area gets cut inbound instead of outbound. I'll have to try that next time.I ran into the same problem on my Tau Zero's inner fins when I tried to orient them the way Carl has them laid out on the laser-cut sheet (http://www.semroc.com/Store/scripts/prodView.asp?idproduct=944). (That's why Prototype I has the balsa grain running parallel to the body tubes.)

Yeah, I could use that "Laser-Finger," too. :rolleyes: ;) :D


Cheers,

[CPMcGraw]

I ran into the same problem on my Tau Zero's inner fins when I tried to orient them the way Carl has them laid out on the laser-cut sheet (http://www.semroc.com/Store/scripts/prodView.asp?idproduct=944). (That's why Prototype I has the balsa grain running parallel to the body tubes.)

Yeah, I could use that "Laser-Finger," too. :rolleyes: ;) :D


Cheers,

So Carl runs the grain in the more traditional "outbound" direction for his version. I wonder if maybe this is one of those applications where his 0.05 cardstock would be a better choice, since it has a more unidirectional grain...

I've priced a few "laser fingers"; my wallet kept coming back more hole-y than righteous...