Scratchbuilt alien atmospheric probe

[Bill S]

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).

 

[Sandy H.]

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.

 

[Lee]

Nice graphics

 

[BABAR]

Have you been stealing paint from @rklapp ?

 

[neil_w]

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

 

[Ronz Rocketz]

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

 

[Bill S]

Have you been stealing paint from @rklapp ?

Nope. Basecoat is Tamiya Coral Blue, decals were a medium purple (wanted ligher but my printer wouldn't cooperate).

 

[Bill S]

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.

 

[Ronz Rocketz]

Nope. Basecoat is Tamiya Coral Blue, decals were a medium purple (wanted ligher but my printer wouldn't cooperate).

Wait, I do have a missing can of paint. Are you sure?

 

[Ronz Rocketz]

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.

 

[les]

Fantastic job!

 

[Bill S]

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]

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.

 

[Ronz Rocketz]

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

 

[Bill S]

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.

 

[Bill S]

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!!!

 

[GlenP]

Probably just some minor tweaks is all you need to make that into great flier, that’s part of the hobby. That nose and those strakes and decals really make a great looking rocket. Say you make the strakes over only the lower half of the rocket to also help shift Cp aft a bit?

I have found that the print at home decals are only color accurate when applied on a base white background. I tried to put a decal of yellow letters on a blue rocket, but they came out green, for example. You can put down a layer of white decal paper first and then a second layer of the printed color to help make it more color accurate over a darker background.

 

[Bill S]

You know, I am actually giving thought to shortening the strakes to half length - basically cutting them in half. I don't know what to do, if anything, about the rear fins. I suspect they need to be taller, but removing them and putting on taller ones is a) going to take a fair bit of work, and b) it'll be nearly impossible to do so neatly and not look like crud.

 

[dhbarr]

You know, I am actually giving thought to shortening the strakes to half length - basically cutting them in half. I don't know what to do, if anything, about the rear fins. I suspect they need to be taller, but removing them and putting on taller ones is a) going to take a fair bit of work, and b) it'll be nearly impossible to do so neatly and not look like crud.

I think your strakes are interfering with the effectiveness of your fins. If they were directly inline with your fins OR they terminated a diameter or two in front of your fins OR if your fins were about ~10% taller I think you'd be in better shape.

What about leaving the current fins in place and just building them up? Styrene cheeks, for example to firmly hold a little more tip and aft plus some panel lines?

 

[GlenP]

maybe add a ring fin, or three smaller dia tip ring fin/pods to each fin?

 

[icyclops]

It’s not the strakes….it is your fins…way too small for that size/length of rocket…Sim programs usually fail with smaller fins as there are too many elements evolved in determining stability just due to body to fin size….not overall surface space but enough of the right surface space sticking out far enough to compensate for react stability. Increase the height of your fins and you will see.

 

[Bill S]

I'm in the midst of totally redesigning the rocket, but thanks icyclops.

 

[Pem Tech]

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).

View attachment 481910

View attachment 481911

View attachment 481912

View attachment 481913

View attachment 481914

View attachment 481915

Nicely done. She is eye catching and very shapely. How does the CP/CG ratio work out? The tiny aft fins may not provide sufficient stabilization. Other than that, good work!

 

[Bill S]

Nicely done. She is eye catching and very shapely. How does the CP/CG ratio work out? The tiny aft fins may not provide sufficient stabilization. Other than that, good work!

According to Rocksim, CP is 21.06" from the nose tip, CG is 13.92", stability margin is supposedly 5.39. Using the heaviest motor I designed it for (D12-5), CP is 21.06" and CG is 17.68", stability margin is 2.55. Stability with the C11-5 motors I flew it with is 3.07.

I tend to agree the rear fins aren't wide enough; I'm totally redesigning the rocket to make them wider, shorten the strakes + have them aligned with the fins (blend into them essentially making one loooong fin), reduce the length of the strakes as well. I'm also fiddling with making the center of the body a BT-60 tube with cut down plastic nosecones as transitions so the front and rear are BT-55. Have some other projects to work on right now, so its on the back burner for now.