DE-Ligthtful (2x D/E build thread)

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matthewdlaudato

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Just a quick build thread for a simple 2 motor cluster rocket that will use D or E motors. Starts like this:

ImageUploadedByRocketry Forum1504371198.011864.jpg

Had some Fliskits BT-70 tubes and a nose cone laying around, so designed this 3FNC rocket.
 

matthewdlaudato

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The BT-70 tubes are tied together with a 4" long coupler (also from Fliskits). Decided to glass to get some stiffness. Here's the prep for putting a single layer of 4oz glass on the joined tube. I have 10 yards of the 4oz plain weave, this barely used a foot. The OLFA 45mm cutter is a must-have - with a straight edge to guide it, nice clean cuts in the glass fabric every time.
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matthewdlaudato

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The glassed tube and some other parts. I bought the cluster motor mount from Fliskits as well - but just used the centering rings as templates to cut my own from 1/8" plywood. Stuffer tubes are 9" long to help get good pressure in that somewhat long body tube. Fins are simple trapezoidal, also cut from 1/8" plywood (have a lot of that laying around the shop as well.)

ImageUploadedByRocketry Forum1504371870.318247.jpg
 

matthewdlaudato

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Motor mount and centering rings. Used standard Estes E engine hooks (3.75" variety); with a spacer the rocket can fly on 2 D motors as well (hence the name DE-Lightful).

ImageUploadedByRocketry Forum1504372015.965074.jpg
 

matthewdlaudato

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Aft ring epoxied in place. I use Loctite 5 minute epoxy on these quick builds.

ImageUploadedByRocketry Forum1504374993.727082.jpg

Forward ring is ready to be mounted, with the Kevlar thread in position but not yet epoxied. I'll tie some 1/8" sewing elastic to the other end for a more than adequate shock cord for this rocket.
 

matthewdlaudato

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Mounted the fins using the Loctite 5 minute epoxy. Will get fillets eventually.

ImageUploadedByRocketry Forum1504379717.897738.jpg
 

matthewdlaudato

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Completed motor mount. Kevlar thread epoxied in the channel, not going anywhere.

ImageUploadedByRocketry Forum1504399237.918825.jpg
 

KarlS

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I would use 1/4" braided nylon elastic for the shock cord. Regular sewing elastic is NOT good enough for shock cord except for few flights.
 

MALBAR 70

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Looking good Matt. Will we be seeing this at the Fliskits anniversary launch on the 16th?
 

Nytrunner

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Got to love that Loctite HD 5min.
I've found my usage has slowed down as I've gotten better at applying wood glue (and my rockets have gotten lighter as a result!)
 

matthewdlaudato

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I would use 1/4" braided nylon elastic for the shock cord. Regular sewing elastic is NOT good enough for shock cord except for few flights.
I'll have to get some. But since in this rocket it's a replaceable part that I check before every flight, not too worried.
 

matthewdlaudato

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Got to love that Loctite HD 5min.
I've found my usage has slowed down as I've gotten better at applying wood glue (and my rockets have gotten lighter as a result!)
Hah, yeah it's a bit beefy. I certainly could have used wood glue on this little bird.
 

matthewdlaudato

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ImageUploadedByRocketry Forum1504555529.548287.jpg

Installed the 10/10 rail buttons using weld nuts - used JB Weld to secure the nuts to the inner tube surface.

Rocket stands just shy of 44" tall and currently weighs in at 226g (8 ounces).

Still needs fin fillets, then on to final prepping and painting.
 

LithosphereRocketry

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Every time I see a 24mm MMT I suggest a CTI G65 WH LB... Here you're glassing things, so it might actually be somewhat sane!
 

matthewdlaudato

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ImageUploadedByRocketry Forum1504569106.544764.jpg

Starting the fin fillets. West Systems 105/205 with enough 406 colloidal silica mixed in to make a creamy paste. Smoothed it out with a plastic spoon dipped in denatured alcohol, used gloved finger also dipped to clean up excess.
 

matthewdlaudato

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Every time I see a 24mm MMT I suggest a CTI G65 WH LB... Here you're glassing things, so it might actually be somewhat sane!
It would really move on a pair of those! But alas, I built it to use BP motors. Glassing was mostly because the BT-70 tubes are a bit flimsy (and to get more glassing practice!)
 

matthewdlaudato

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ImageUploadedByRocketry Forum1504829481.438330.jpg

One set of fillets had rough spots due to me overdoing it with the colloidal silica mix. Sanded it down as best I could, Bondo and more sanding will take care of the rest. Will sand and similarly touch up the other fillets, but they are much smoother and won't require too much attention.
 

matthewdlaudato

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Bondo sanded down, now on to first primer coat. I use Duplicolor Filler Primer, couple of light coats with sanding in between, maybe some spot filling with more Bondo if I see some rough areas. Creates a stable base for the finish costs.
 

matthewdlaudato

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Finish painting in progress. Fin can area is black, taped off now to get the body painted silver. Haven't decided whether nose will be black or white.
 

matthewdlaudato

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Completed rocket. With an 24" nylon chute inside weighs in at 300g (about 10 1/2 oz).
 

stealth6

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Congrats on the build and flight.
Bootsy thinks it's groovy......

[video=youtube;62_xQU6HVD4]https://www.youtube.com/watch?v=62_xQU6HVD4[/video]

s6
 

matthewdlaudato

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Only post flight note is that the descent rate seemed a bit fast. The chute was 24", so maybe next time I'll use a 36".


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