Build thread: Plasma Dart

[neil_w]

This rocket was first cooked up about three years ago and started me on my plasma-core kick. It has seen remarkably little design modification since the first unveiling (only the canard-like appendages on the strakes have been added.) The paint scheme, however, has been churned endlessly, and I'm still vaguely dissatisfied with it, particularly the fin decals. I expect to fiddle with it more before the time comes to print decals. Given the pace at which I build, that gives me a nice long time to work on it.

Which brings me to my standard disclaimer: my builds are quite slow and leisurely; if you're looking for instant gratification you're in the wrong thread. Check back in the fall. @kuririn will complete twenty rockets (or more!) while I'm plodding through this one. @bobbyg23 has built, painted, decaled, clear-coated, and flown a model just while I'm typing this sentence.

Here's the OR side view, configured with an E30:

I'm on a kick of making my rockets a bit bigger, after being bitten by building the Plasma Dart II too small. Not like this is huge or anything, but it's one click bigger than I had originally planned, and will be best suited for Ds and Es. The biggest reason was that the core tube is BT55, which is so much easier to work with (for stuffing parachutes and wadding and whatnot) than BT50.

Thus ends the introduction. First build entry later tonight.

NOTE: above images updated to reflect latest design.

 

[boatgeek]

Woo! A Plasma Dart build! If it makes you feel any better, you build faster than I do.

 

[Ted Cochran]

Cool! Did you try the paint scheme with the decal at the aft end of the white fin, and the lighter colors at the top, and then going from dark to light starting at the leading edge of the black fins? Just a thought...

 

[neil_w]

If it makes you feel any better, you build faster than I do.

It does, a little.

I do wish I could provide more than a slow trickle of minutiae, but I can only do what I can do. So be prepared for a slow trickle of minutiae.

 

[mbeels]

Alright! I really like that color, BTW, I think it suits this rocket really well. Plus its a great contrasting color for sitting next to the PDII. Will it be big enough for your new chute release? Or does that require something larger?

Which brings me to my standard disclaimer: my builds are quite slow and leisurely; if you're looking for instant gratification you're in the wrong thread. Check back in the fall. @kuririn will complete twenty rockets (or more!) while I'm plodding through this one. @bobbyg23 has built, painted, decaled, clear-coated, and flown a model just while I'm typing this sentence.

!!!!

 

[neil_w]

Cool! Did you try the paint scheme with the decal at the aft end of the white fin, and the lighter colors at the top, and then going from dark to light starting at the leading edge of the black fins? Just a thought...

I'm having a hard time picturing what you're describing. Could you give it another shot?

 

[neil_w]

Alright! I really like that color, BTW, I think it suits this rocket really well. Plus its a great contrasting color for sitting next to the PDII.

It's going to dwarf the PDII. And yet...

Will it be big enough for your new chute release?

...not big enough. JLCR requires at least BT60; the laundry tube here is BT55. You're free to build an upscale, you could make a much better matched set than mine.

 

[Ted Cochran]

Sorry for the lousy explanation. Look at the top picture. Flip the color progression on both fins—light to dark on top, dark to light on the bottom. Now move the top decal to the aft end of the white fin, So the darkest bar is on the trailing edge. The lightest bars on the white fin would be close to/adjacent to the lightest bars on the dark fin. Just a wild idea I had...

 

[neil_w]

GETTING STARTED

In a change from my usual sequence, I'll be starting with the front of the rocket first. I decided to split the rocket between the two front transitions; it seemed a bit risky but would make the build a bit more interesting, and give me a payload section up front for an altimeter. So I will first construct the entire payload section.

Step one is the front transition. Because it's relatively unprotected up there, I decided to do my own version of a super-shroud, using a technique I've used a couple of times with success.

First, the basic transition is made from 110 lb card stock, my new go-to. I made this one with the tab in the back, to keep the surface smooth.

Next I added the second layer. I cut another shroud, and then remove a piece from the end roughly the size of the tab I used to connect the original. Then glue in the second piece:

Its hard to get it perfect but I did a decent job here. This approach leave exactly two layers around the entire shroud, with no extra thickness where the connecting tab is to create an unsightly bulge. The inner piece does not quite go to the front of the outer piece, else it won't fit on the body tube.

I always set my cardstock shrouds on an appropriately sized body tube and centering ring to dry, to maintain perfect roundness. That's a lite ply 5570 centering ring, with the edge beveled so that it just fit inside the end of the shroud.

When it is completely dry, the excess inner shroud is trimmed off and the edge is sanded flat.

 

[neil_w]

Sorry for the lousy explanation. Look at the top picture. Flip the color progression on both fins—light to dark on top, dark to light on the bottom. Now move the top decal to the aft end of the white fin, So the darkest bar is on the trailing edge. The lightest bars on the white fin would be close to/adjacent to the lightest bars on the dark fin. Just a wild idea I had...

Still not 100% clear but I will throw together some mockups and you can guide me from there.

 

[Nytrunner]

To paraphrase the ex-con marine from the StarCraft 2 trailer: ".....It's a-bout timmmme"

Looking forward to it!

 

[neil_w]

Cannot concentrate on work here while the air elemental is throwing a tantrum outside, so I'll post a small update.

The centering ring was glued flush to the end of the tube, and then the shroud was glued on top of it, pushed down as much as reasonable to get it flush with the ring. Glue was applied only to the ring, not to the body. That is a lesson I learned in a previous build.

The small side of this shroud turned out o be just a wee bit large, leaving a gap or two around its circumference.

A small amount of TBII was rubbed around the joint to seal it up. Looks good.

I am not particular good at filling and smoothing the joint between the small end of the shroud and the body tube. This time I did it mostly with thinned CWF, followed with a wipe of thin CA. The thin CA was also applied to the entire shroud at this point to harden it up and (after sanding) provide a nice smooth surface for painting. The shroud seam was filled a bit as well.

Came out good and very solid.

Oh, the piece of body tube was completely covered in thinned CWF for seam filling, as is my standard practice now. Continues to work well.

 

[mbeels]

The centering ring was glued flush to the end of the tube, and then the shroud was glued on top of it, pushed down as much as reasonable to get it flush with the ring. Glue was applied only to the ring, not to the body. That is a lesson I learned in a previous build.

That shroud looks really solid. I'm curious though, why no glue to the body?

 

[neil_w]

That shroud looks really solid. I'm curious though, why no glue to the body?

I've had it seize before the transition was in place. Also, makes a bit of a mess if you drag the transition over the glue bead, until you position the glue bead very precisely at the right position. It is probably possible to do it neatly, but I realized that there's no need. With a good glue joint between the shroud and the centering ring, the shroud is not going anywhere. The small fillet around the shroud/body seam is more than sufficient to seal and anchor that joint, with no mess.

I should also add that this is the first time I did it this way. Worked well, I will continue to do it this way until something or someone convinces me otherwise.

Also, in case where there's a tail cone flush with the end of the motor mount, I *will* glue that seam when installing.

 

[neil_w]

Here's my crack at Ted's suggestion. It didn't really work to have the design on the black fin sort of transition into the one on the white fin, but it's worth considering the general approach of having the design aligned with the back of the fin rather than the front. Here are the two variations for comparison:



That's just my first quick take. Not sure which way I like better. There is more fiddling to be done.

 

[Ted Cochran]

They both look great, although I do like the top one! Have you looked at making the fin can body tube black?

 

[Wally Ferrer]

Here's my crack at Ted's suggestion. It didn't really work to have the design on the black fin sort of transition into the one on the white fin, but it's worth considering the general approach of having the design aligned with the back of the fin rather than the front. Here are the two variations for comparison:
View attachment 426997
View attachment 426999

That's just my first quick take. Not sure which way I like better. There is more fiddling to be done.

I like the second iteration, but I would take the lettering and also align it with the rear edge of the fin or move it to the tube along the root edge...

 

[neil_w]

I like the second iteration, but I would take the lettering and also align it with the rear edge of the fin or move it to the tube along the root edge...

 

[mbeels]

I do like the text not overlapping the stripes. It stands out much better that way. The only downside of that arrangment is that the text will be upside down while the rocket is on the rod. What about flipping the text top to bottom, or a complete graphics rotation of about 120 degrees? A quick and dirty:

 

[neil_w]

I see what you mean (I thought of the upside-down-on-the-pad issue as well), but I don't know if I want the strips running parallel to the fin leading edge, seems kinda boring. Although it does work well with the (completely superfluous) text.

More work needed.

 

[jqavins]

A few tings, as I'm a few days late.

The paint scheme on the nose cone and payload section tube creates an interesting illusion in the shots that are nearly front-on, like the center bottom in the first post and your current profile pic. From such an angle it looks like the tube section has a slight taper, with the bottom of the nose cone being the largest spot. Of course, it's obviously not that way once you see the side view, but from the front it looks like the side view will be different. The illusion, the way the eye is tricked, is good. I like it.


I like the one fin as a different color from the other two. I often am drawn to patterns that employ two different, contrasting symmetries, in this case the three way shape symmetry of the three fins against the two way symmetry of the paint scheme.

The color stripe fade is obviously derivative of Blackfish. Which is fine if you want to use a theme you like more than once. Yet maybe if you're not satisfied with it it's because part of you wants to find something new.

If using the stripes is a given, I like the top one better than the bottom in post #15, because there's more of the strips. In the original, the stripes are so short that they cover a very small fraction of the total fin area, and they have little effect. Reversed, they stand out and brake up the fin much better.

As for the lettering, and if you go with the larger stripes on the fins, you could just move the lettering off the fin and onto the tube, parallel to the fin root and close to it; not right up against it, so there's a small gap.

That's it for now.

 

[neil_w]

The color stripe fade is obviously derivative of Blackfish. Which is fine if you want to use a theme you like more than once. Yet maybe if you're not satisfied with it it's because part of you wants to find something new.

Although it is true that I tend towards repetition of design themes, this design by far predates Blackfish, and anyway fades are pretty common design elements. However, I'd be quite happy have something different for the fins.

If using the stripes is a given...

It is not. It's just what I have for now.

I went back and looked and an older revision of this design had more stripes covering more of the fin:

Not sure why I went away from that. Perhaps I should revisit something like this old design, which I still like:

That gets away from the stripes and the fade entirely.

Apologies to anyone who thought there would be any actual rocket building on this thread. It'll happen, I promise!

 

[Nytrunner]

I do like the grating/stripes. Makes it look like there's a collector or vent in the fins

 

[jqavins]

Although it is true that I tend towards repetition of design themes, this design by far predates Blackfish...

Understood, but Blackfish was built first. Not important.

What about more and thinner stripes, with a more gradual fade so the total area covered is greater?

 

[boatgeek]

...
Apologies to anyone who thought there would be any actual rocket building on this thread. It'll happen, I promise!

As Eeyore says, "Thinking first and then hard work." It's fun watching your designs evolve from the merely cool to the excellent.

 

[neil_w]

Fiddle fiddle fiddle.

 

[mbeels]

Hmm.... interesting, that feels like a step in a good direction. I do agree with Nytrunner:

I do like the grating/stripes. Makes it look like there's a collector or vent in the fins

I like them as well. What about adding the grating/stripes to the color wedge above the text?

 

[jqavins]

Wild idea: How about making the plasma pattern in the fins' wedge or stripes in a different color? Don't get me wrong, that orange looks great. It might work, though, to do a different color on the fins. Say, red for example, as if the plasma has cooled before reaching the fins. Or green or blue; a heat pump moves heat from the engine plasma (orange) into a higher temperature coolant plasma which, being hotter, can radiate the heat away to space more effectively when it cycles into the cooling fins. (Everyone knows that there is no point to aerodynamic fins in space, but thermal radiators are a necessity, and if they happen to look like aerodynamics that's just a coincidence.) And the pew-pew sticks are on the fin tips because they generate a whole lot of heat when fired, so they have to be right on the radiator surfaces.

 

[neil_w]

Yet another approach, brings back the stripes. I kind of like this one for the moment.


I swear there will be an actual build update soon.

 

[Wally Ferrer]

It's ok, you obviously need to figure out the logistics of the plasma cooling interface in the fins before you can start construction, otherwise there will be delays and cost overruns, etc...