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  #1  
Old 03-23-2018, 01:43 AM
BARGeezer BARGeezer is offline
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Default EVR Star Scythe build

This will be a build of the EVR (Echo Victor Rocketry) Star Scythe. For background and a picture of the completed rocket please read this thread:
http://www.forums.rocketshoppe.com/...54&page=1&pp=10

I received a response back from EV, he sent me detailed, well written and illustrated assembly instructions. Apparently a few years ago he was planning to kit this design, but the numbers didn't work out so he shelved this. So together with the fins from Semroc/erockets, instructions, and parts from my stash, I only needed a couple of things to start building. Here we go:


The parts:
BT-60 body tube
PNC-60 nose cone
20-60 centering rings
Laser cut fin set
Engine tube, thrust ring, hook, and mylar hook retainer
18" parachute pak (sub for 16" pak)
Elastic shock cord, kevlar cord
Tube marking guide, fin alignment guide, and canopy template (not shown)
Adhesive backed letter size label paper (to paper the fins)

Upon first glance at the fins, my concern was for the way the grain ran . It was cut near perpendicular to the pointy fin tips. Very susceptible to damage upon landing. I will be painting the wood with thin CA to fortify them prior to papering. Will also paint the paper skins with CA after attaching to the fins. Hopefully that might mitigate any landing damage. Will finish up tonight by assembling the motor mount. Painted fins and motor mount will be dry by tomorrow. TBC
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Last edited by BARGeezer : 03-23-2018 at 02:35 AM.
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  #2  
Old 03-23-2018, 03:55 AM
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ghrocketman ghrocketman is offline
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If you could get Semroc to cut the fins out of Basswood like some of their SLS mid-power line, they would be FAR more durable.
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  #3  
Old 03-24-2018, 10:19 AM
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EchoVictor EchoVictor is offline
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BAR,

The label paper does alright, but will start to show some wear after a few launches.

After several cracks on my own prototypes, I wound up cutting up a manila folder and laminating the top two rear fins with that.

Good luck,
EV
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  #4  
Old 03-24-2018, 11:35 AM
BARGeezer BARGeezer is offline
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Thanks EV, will keep that in mind for future repairs, since I already papered the fins. Next post coming up probably tonight.
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  #5  
Old 03-25-2018, 09:29 AM
BARGeezer BARGeezer is offline
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After drying overnight, the motor mount is glued into the body. My method is to put a bead of glue into the motor tube. Then insert the motor mount partially into the tube. Put a second bead in the tube behind the top centering ring. Then push the mount into the final position in the tube. Follow with a bead around the bottom of the lower centering ring. This way 3 of the 4 sides of the centering rings have a bead of glue around them.
The CA seems to have hardened the balsa fins considerably. No more flexing at the tips or sponginess. At this point I deemed it safe to try sanding the edges of the fins. But I had a small accident, one of the tips broke off. Easily repaired, but I abandoned plans to put a knife edge on the leading edges. Instead, I slightly rounded all edges of the fins/wings. Earlier I had traced both sides of the fins onto adhesive label paper. I cut these out, including a strip at the leading edges which will be painted silver to simulate a cutting edge. After all, this is the Star SCYTHE. I'm glad EV didn't call it the Star Sickle. That sounds like a frozen novelty treat. Or the Star Sith, which would be in a whole nother galaxy, far, far away.
....................
But, I digress.
The skins are then applied to the fins/wings, and any excess is trimmed off with a hobby knife. The paper was then painted with CA. Be careful when painting the fins and skins with CA not to get any on or near the root edges. Wood glue does not adhere well to CA impregnated wood since the pores are filled. Notice the rear fins are labeled TF and BF. Two of the fins have the pointy end facing rearward ( the top fins). The other bottom fin has the pointy end facing forward. Interesting design feature.
While the skins were drying I printed the canopy template onto 110# cardstock. The template drawing is not full size but there is an inch scale, so some measurements and a little math and I was able to calculate how much to upscale the copy. The canopy was cut out and folded. For cardstock items (shrouds, nozzles, canopies) you only need a bit of glue on the tabs. My standard procedure is to paint all cardstock items with CA. This helps to lessen any creases or dents from hard knocks.
Earlier I had cut out the tube marking guide and marked the locations of the fins, wings, and canopy. I extended these markings with an angle tool. Now comes the fun part. Instructions say to use the double glue method of attaching the fins. But impatient as I am, I didn't want to wait for the first glue film to dry overnight. So my procedure is to apply a film of wood glue to the root edge, leaving a space at the ends to apply a drop of CA. Then I attach it to the body tube holding in place for a few seconds to a minute for the CA to grab. To ensure perpendicularity I align the fin with the leg of a display stand by line of sight. Be sure the fin is in position when the CA grabs, otherwise you will have to break the joint and start over. Rotate the display stand and align a leg with each fin until completed.
Then I glued on the canopy. Next post, fillets, primer, and paint. TBC
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  #6  
Old 03-26-2018, 12:06 PM
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EchoVictor EchoVictor is offline
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BAR,

looking good so far.

On the double glue joint method, you don't have to wait overnight for the first joint to dry. Using Elmer's Wood Glue, it only takes about 5-10 minutes...

Thanks,
EV

P.S. Check your email for the decal file
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  #7  
Old 03-26-2018, 01:15 PM
BARGeezer BARGeezer is offline
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Quote:
Originally Posted by EchoVictor
BAR,

looking good so far.

On the double glue joint method, you don't have to wait overnight for the first joint to dry. Using Elmer's Wood Glue, it only takes about 5-10 minutes...

Thanks,
EV

P.S. Check your email for the decal file



Thanks EV. Got the decal pdf. Was reading a thread on how long to let the first coat dry on the double glue method. Opinions ranged from a few minutes to completely dry. So I went with my method. When the CA grabs, it ain't going nowhere. Takes about a minute. Will be taking your advice on printing the decals on white paper with a black background. I've printed lighter colors on clear decal paper before and they have virtually disappeared on a black model. Printing and clear coating should take a couple of days. BTW I was thinking a flat black with a matte/satin clear coat for the rocket finish? What do you think? I know decals over a flat finish might result in silvering, but I have had success using MicroSol/Set to prevent that.
And I'll be rigging the traditional (vertical) chute harness, but what do you think about a harness that will bring the rocket down horizontally, to lessen landing damage to the fins? Similar to the LEM/SM recovery rigging on the Estes Saturn V.

Thanks for your input, next post probably tonight or tomorrow. Laters.

Last edited by BARGeezer : 03-26-2018 at 02:00 PM.
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  #8  
Old 03-26-2018, 02:12 PM
BARGeezer BARGeezer is offline
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Ah! I just thought of something: Pop pod motor mount with rear ejection. The rocket would land nose first. Any opinions? Something to think about for a second build. Erockets gave me a fin set that included four wings and four rear fins. So I have two wings and one rear fin extras. All I need to do is trace out two more rear fins for a second set.
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  #9  
Old 03-28-2018, 07:56 AM
BARGeezer BARGeezer is offline
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The good thing about papered fins and a plastic nose cone is there's no wood to fill on this model. Two launch lugs were glued halfway up the lower wing/tube joints, then all joints and canopy seams were filleted. While the fillets were drying, I assembled the parachute pak. Instructions call for a 16", and I only had an 18" pak, but I think the slightly slower descent rate from the extra 2" will help the fins at landing. After the fillets dried the rocket was given a coat of automotive sandable primer and after drying was lightly sanded. Then it was given a coat of flat black paint. It's starting to look sinister now. I'll let this completely dry, touching up any missed spots with the brush, and do the decal work in a couple of days, along with the nose ballast. Almost there.
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  #10  
Old 03-28-2018, 11:47 AM
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EchoVictor EchoVictor is offline
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Quote:
Originally Posted by BARGeezer
BTW I was thinking a flat black with a matte/satin clear coat for the rocket finish? What do you think? I know decals over a flat finish might result in silvering, but I have had success using MicroSol/Set to prevent that.


Good luck with the MicroSol. I've found that while it works fine with mass-produced decals, it wound up dissolving the ink off the ones I printed myself. Thus the idea of a satin base coat and going matte with the clear coat....

Either way....looking great!

Thanks,
EV
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