18mm Star Trooper

I added 3 cm to the body tube, but otherwise this will be an upscale of my Estes Star Trooper.
1 wrap of .75oz with a nearly invisible .25" seam.
The fins will be some kind of composite structure of paper and glasscloth.
I have plenty of Balsa in all sorts of thicknesses, but I want to try something new.

I've decided that I'll do two sets of fins, so we can see the weight differences between the new method and the method I used on the 13mm version. On that one I sandwiched a piece of FG cloth between two pieces of balsa to be able to sand my angles properly, having a clearly visible center line. The composite fins will simply take advantage of the fact that paper can be folded to make angles.
I experimented with this concept briefly on my cardstock mini Blue Bird Zero.

Well, after a couple of attempts to come up with a decent set of fins using my paper ideas, I think I will just make them like the set from the 13mm version.

I'll use the sandwiched piece of Fiberglass between two pieces of balsa like I did on the 13mm, but this time I'll actually use thinner balsa.

I got the fins under some books and weights and sitting ontop of a small marble slab that was once a cutting board type kitchen accessory or decorative piece. It was broken when I found it in the woods, but I recognized the usefulness of the perfectly flat surface for smaller stuff like this, where I don't have to drag out my granite slab.
As I did on the smaller one, I'll wait an hour then check them to make sure they have not shifted, though I suspect they won't as I'm getting better at this method.
I use 5oz. glass for this, which sounds heavy, but really is not, and I can use thinner balsa, so it's all good.
The 5 is easy to see the edge on, so you can sand it pretty nicely.
I'm working on this technique to make the fins for the boosters on my SA-5, and if this set for the Star Trooper come out nice, I'll go ahead and put the booster fins together.
Thanks again to forum member sunderll for introducing me to this technique!

Before I start sanding, the fins weigh 3g.
I have a plastic Estes cone for this build from an Aston Elliptic II, but it is 6g. vs. the balsa paperclay composite one I made that weighs 1g. before adding a shoulder to it. I think I'll make up my recovery gear and see what my CG is with the lightweight cone vs the heavy plastic one before making up my mind on which one to use.
This thing is meant to disappear on a single use D21, but we'll let it get a couple of rides on BP motors first. I'm pleased to see my balsa/paperclay cone making method can't be bitched about by the weight nazis. I've made them smaller, but am slowly making them larger as my skill at turning them increases, and the 18mm size is my largest yet.

Got started beveling the fins yesterday, and the 13mm version really moves, so this one ought to teleport on 18mm Composites.

I'm getting the fins on her tonight.

There we go!
I decided to go with more of an airfoil than the faceted style that I used on the 13mm version.
I'll just keep the plastic cone with some mods that I need to make.
Unpainted and before recovery gear and buttons, it weighs about what the smaller one does finished without motor.

I got the mount for the buttons completed.
As usual, I'll use the screws that work like greased lightning on the smaller version, but in the process of designing this mount, I developed a new type of button for Makerbeam, from a tiny finishing nail, by drilling a hole in it, then cutting it.
I'll work that into a future build, like a fiberglassed 220 Swift or something similar.
The hole will facilitate mechanical attachment via wire, dowel pin or toothpick pin, and since it is painted and has no threads, it too should be greased lighting in Makerbeams.



The mount for this bird is made from a piece of one of the tubes that Aerotech uses for their Copperhead Igniters, hardened with CA, then I made two hard points from precisely fitted basswood, with a little JB Quick, then sanded smooth, drilled and tapped, and then, when the screw buttons were in there for good, I used a chainsaw file to smooth them to exact fit with the BT.
The channel in between the hard points will be left hollow to save weight, and then the gap at either end will get filled with paper clay, as that weighs nothing when dry, so it makes a great filler for some things.

I got primer on her today, and she'll be flying soon. Nothing really exciting designwise after the mount for the screw buttons, so next time I revisit this thread, it will be with launch vids and pics of final paint.

I did assemble my 13mm Carbon Fiber version today, and will do a 24mm and 18mm soon in CF too.

I like the Star Trooper design as much as I like the Crossfire, so many versions are warranted.

13mm CF Star Trooper?! That's so ridiculous it's awesome!!!

Screaminhelo said:

13mm CF Star Trooper?! That's so ridiculous it's awesome!!!

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Thanks!

I got the primer sanded and filled a couple of small dents on the fins with Bondo spot & glazing putty.
It's hard not to dent the balsa while handling it, but the results of the "Two pieces of balsa with a piece of 5oz. glass cloth sandwiched between them" method are well worth it. I sealed the balsa with epoxy before the primer, so it is plenty durable now, but the primer showed where my fingernails must have dented it. I'm getting better about properly preparing everything before paint, and it is worth the added effort.
That's outside drying now, so later I'll sand it and get my final primer on there.
Should be flyable within a few days.

Here's the second coat of primer. Still needs a little fine tuning in a few tiny spots, but overall it's lookin' good.



I finished the 13mm version, and it's ready to fly.

Looks good! Looks VERY good! Got good weather tonight and tomorrow...

adrienwapkaplet said:

Looks good! Looks VERY good! Got good weather tonight and tomorrow...

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Thank you!

Yeah, the weather is great for painting, but it's too hot for me to be enjoying it.
If it is cool and windless tomorrow around 6:00 AM-ish, I might try to get a flight or two in at the park.

TopRamen said:

i finished the 13mm version, and it's ready to fly.

View attachment 292272

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Looks great!

cavecentral said:

Looks great!

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Thank You.

I'll be flying that CF you gave me, just like I said I would.
It is such a joy to work with, and a pleasant change from the glass cloth.
I'm glad I figured out how to do the fins from many pieces. I used the same technique to make the rail guide.

I am curious, how does the weight of the CF version compare? I see that it weighs 15g, that is not much. Does the "kit" build come anywhere close to doubling that?

Screaminhelo said:

I am curious, how does the weight of the CF version compare? I see that it weighs 15g, that is not much. Does the "kit" build come anywhere close to doubling that?

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The Estes kit does not have the mass to attain altitude through momentum, so while this one weighs about the same as my glassed version, I flew it on an A3 with a 4 second delay, and it went crazy high.
Estes list the Kit at 8.5g. but it slows rapidly after motor burnout, and even OR confirms this.

Here's tonight's launch. :

[video=youtube;8bloYEvuGGs]https://www.youtube.com/watch?v=8bloYEvuGGs[/video]

Oh no! Did you get it down?

Marc_G said:

Oh no! Did you get it down?

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Yes, ofcourse.

My Son was able to reach it after I grabbed the small tree and gently shifted it groundwards.
I have a chainsaw and an attitude for when trees get stupid, but this thing was like a foot out of reach, and the trees as of late have been catching my rockets to prevent damage, so I think I have finally won them over to my side. They've been doing me favors to avoid the Chainsaw I suppose.
Just look how gently they cradled my TLP Indigo, they saved it from the power lines on purpose. Thanks Trees!:



They are my friends now.

I sprayed a coat of white semi-gloss rusto 2X on top of the sanded primer, so that the yellow would be bright, and it worked out like I thought it would. Little attention was paid to the fins, as they will get the Krylon Banner Red, which has proven to go on top of Rusto 2X quite well in the past.
Same paint scheme as the 13mm FG version.
I'm going to make the recovery gear for this one optional, in that it will use a quick connect swivel, so I can fly a tiny chute' on A and B motors, or a streamer and whatever on composites up to D.
This is going to be a very fun rocket, as I only have a couple 18mm rockets in my fleet.
I will be able to do a very wide range of Openrocket simulations on it, so it will be a fun study of the designs aerodynamics.
These things are "Food for Thought", and my mindsim just devours them like it has a tapeworm, and cannot get enough nutrients. The constants like CP and location of components stays relatively the same, yet the variety of materials and construction techniques I can play with are boundless! The Star Trooper finds it's way into my dreams on a frequent and expected schedule.

Really like this one. The Star Trooper is a really elegant design.

Flyfalcons said:

Really like this one. The Star Trooper is a really elegant design.

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Thanks, and glad you like it.
It really is a great design!
I'm generally not a fan of 3FNC rockets, but a few in particular just really do it for me.
Someday, I'de like to do a BT-80 up-scale of this rocket for 29mm motors. Those fins would look insane at that size!!!:y:

TopRamen said:

Thanks, and glad you like it.
It really is a great design!
I'm generally not a fan of 3FNC rockets, but a few in particular just really do it for me.
Someday, I'de like to do a BT-80 up-scale of this rocket for 29mm motors. Those fins would look insane at that size!!!:y:

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That would definitely be a good place for carbon fiber ridiculousness!!!

You have certainly set my mind in motion with this one. I think that a Star Trooper upscale is in my future. As a matter of fact, I think that it would be a killer L1 cert airframe (not there right now but I'll likely get there eventually)

I got the red on there today. It looks good from a couple of feet away. A tiny gnat got into the spray and on one fin, but it was just a tiny spot that you can only see up close, and the second coat filled it okay.
I used ACE brand green painters tape, and even though I rubbed the edges down nice with a Q-tip, I did get a few odd spots.
It's more than good enough for me, so we'll throw some recovery gear in there and see about flying her soon.
I'll try to get a quick clear coat on there, but I have so many things going on that I won't be too bent if I neglect that step.
The Krylon paints are exceptionally durable, as evidenced but the Crossfire that spent a year in a tree.
I'm anxious to get this one done so can focus on the 24mm CF version.

TopRamen said:

I got the red on there today. It looks good from a couple of feet away. A tiny gnat got into the spray and on one fin, but it was just a tiny spot that you can only see up close, and the second coat filled it okay.
I used ACE brand green painters tape, and even though I rubbed the edges down nice with a Q-tip, I did get a few odd spots.
It's more than good enough for me, so we'll throw some recovery gear in there and see about flying her soon.
I'll try to get a quick clear coat on there, but I have so many things going on that I won't be too bent if I neglect that step.
The Krylon paints are exceptionally durable, as evidenced but the Crossfire that spent a year in a tree.
I'm anxious to get this one done so can focus on the 24mm CF version.

View attachment 292574

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A trick that is slightly more practical with an airbrush but useful with buzz bombs as well is to spray the edges of the mask with your base color first and then the new color. This can be a bit of a challenge with spray cans though. You really need to pay attention to paint compatibility when doing this since the two colors will be curing at the same time...not a good time to be bold in your paint combinations.

Nevermind...didn't read the entire post above