Scratchbuilt alien atmospheric probe

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Bill S

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I designed and built this alien atmospheric probe. It uses the nosecone from the Estes Dark Energy, but the rear section is cut off. Its 29" long, uses a BT-55 body, weighs 3.8oz. It will fly on an Estes C11-5 (380 feet), Quest C12-4 (470 feet), C18-6 (470 feet), D16-6 (585 feet), D20-6 (630 feet), Estes D12-5 (770 feet), Aerotech D22-7 (840 feet), and Aerotech E26-7 (1100 feet).

Decals were personally designed and printed. I had originally wanted to use a florescent purple for the majority of the markings, but the paint I purchased had way too much texture for rocket use. So I had to print them out and that was problematic as well. I designed them in Inkscape, but upon printing I discovered they were darker than they were supposed to be. I couldn't figure out a way to lighten them up. Once I put them on the rocket, I discovered that the medium purple turned darker due to the basecoat showing through the clear decal paper material. But I think it still works well.

The alien text is borrowed from the V the movie (1983).

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Sandy H.

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While it might not meet your initial plan as far as the purple decals go, I think it looks great. That's a purple I'd like to be able to duplicate!

I also like the throwback to the 'V' movie/TV series. I had nightmares with that one and wanted to watch more. :)

Sandy.
 

BABAR

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Have you been stealing paint from @rklapp ?
 

neil_w

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Very nice job on the decals. I especially like what you did around the fin can.
 

rklapp

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I have two of those NC in my build box. Guess it’s time I finally do something with it.
 

Bill S

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Here is the Rocksim file if anyone wants to give it a go. Only change I'd probably make is to increase the span of the main fins a little, but that would require adjusting the fin stripe decals (not a big deal). Lenghtnening the body a couple inches would be a good idea as well. The glue weight was higher than expected due to all the strakes (I'd skip putting fillets on those next time).

The weight to balance the D12-5 is because Rocksim says the motor is 1.5oz, whereas actual weight is 1.63 or so, and I can't edit the motor file.

I can upload the decal files if anyone wants them.

FYI, there is an component entry for the 18mm to 24mm plastic adaptor. If using 24mm motors, make sure this is set to .0001 oz. If you are testing 18mm motors, set it to .19oz.
 

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rklapp

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Here is the Rocksim file if anyone wants to give it a go. Only change I'd probably make is to increase the span of the main fins a little, but that would require adjusting the fin stripe decals (not a big deal). Lenghtnening the body a couple inches would be a good idea as well. The glue weight was higher than expected due to all the strakes (I'd skip putting fillets on those next time).

The weight to balance the D12-5 is because Rocksim says the motor is 1.5oz, whereas actual weight is 1.63 or so, and I can't edit the motor file.

I can upload the decal files if anyone wants them.

FYI, there is an component entry for the 18mm to 24mm plastic adaptor. If using 24mm motors, make sure this is set to .0001 oz. If you are testing 18mm motors, set it to .19oz.
I would think the hardest part is glueing the long long strakes without them distorting. What worked best for you?

Can't have too many decal files. Thanks.
 

Bill S

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I would think the hardest part is glueing the long long strakes without them distorting. What worked best for you?

Can't have too many decal files. Thanks.
The strakes were a little tedious to glue on. I treated them like fins, taped down one end, and evey 2-3" or so, put another piece of blue tape to hold it down, but first I looked down the length to try and get them straight as I went along. I did find that too much pressure with the tape could make the strake slip a little to one side or the other, so it was a matter of slightly firm pressure while taping down, not excessive. They didn't turn out perfectly, but close enough.
 

Bill S

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Rklapp, the forum won't let me post the decal files here, as they are .svg files (I used Inkscape to do the decals). I could email them to you if you wanted.

FYI, the files are set up to have enough decals for 2 rockets, with some extras of most of the decals. You could edit the decals down to whatever quantity you wanted.
 

rklapp

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Rklapp, the forum won't let me post the decal files here, as they are .svg files (I used Inkscape to do the decals). I could email them to you if you wanted.

FYI, the files are set up to have enough decals for 2 rockets, with some extras of most of the decals. You could edit the decals down to whatever quantity you wanted.
I see what you mean.

drawing.svg
The uploaded file does not have an allowed extension. The following extensions are allowed: .zip, .txt, .pdf, .png, .jpg, .jpeg, .jpe, .gif, .xls, .xlsm, .xlsx, .ork, .rkt, .rse, .eng, .bsx, .alx1, .cdx1, .stl, .csv, .igs, .iges, .eeprom, .step, ..scad, ..rff, .rff, .fipa, .kml, .kmz, .pptx, .stp, .heic, .scad, .ric, .m4v, .mov, .mp4, .mp4v, .mpeg, .mpg, .ogv, .webm
 
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Bill S

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Well the maiden flight of the probe on an Estes C11-5 was a little wierd. One of the 6 strakes wasn't perfectly straight, and after the boost was over, the rocket turned a little sideways, recovered, and went up. So we are thinking a little more noseweight is called for to help keep the nose pointed up. :( Not a very high flight, but it wasn't supposed to be.
 
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Bill S

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I flew this one two times more, after increasing the noseweight from .16oz to .75 oz. First flight in very calm conditions with a C11-5 was acceptable, with just a tiny bit of wobble on the way up. Second flight, with moderate winds and the same C11-5, it was barely stable, trying to turn sidways but recovering. Naturally the nosecone snapped back and damaged two of the strakes as well.

I can only conclude that a combination of the crooked strake and the rear fins being too small, despite Rocksim giving the rocket a stability of just over 2, I really need to go back to the drawing board and build a second one. I may change/remove the problematic strakes, and will definitely enlarge the fin size. Booooooo!!!
 
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