Upgrading a Blackstar Voyager (Krenim Timeship theme)

[Nytrunner]

Why just build a skill-5 rocket (or is it 6 now?) stock, when you can make life more difficult!

Since there have been a couple Blackstar builds, I was just going to post the occasional update in the "What'd you do today" thread. But interest was expressed in my feeble attempt to improve an iconic rocket, so I figured I'd go ahead and document it. At the very least I can look back and question my sanity later on.

I put the Blackstar on my Secret Santa list, and it showed up in a mysterious triangular box. I have an aversion to 3FNC, so this looked like a good challenge. I also have an aversion to stock paintjobs (just can't compete with the detail accuracy gurus), so I decided I'd try and give it a theme like the Krenim Timeship from Star Trek Voyager.
(so many pieces....)
No redesigns (this thing is hard enough), but a color scheme of grays, silvers, and blues will likely feature. I may have to break down and inquire with Stickershock about recoloring the decals.

Few things I want to do:
-Bigger motors! I grabbed an idea from a previous build and put the short BT-20 at the front end to get the motor block far away. This'll allow me to load longer motors in on the off chance I want to try some long-burning composites or something (or just obliterate the thing with a G). I've got a 24mm retainer on the way via ebay. Longer motors lead to...
-Chute Release! I'm cutting down some of the BT-20 length in the forward BT-60 barrel so I can fit a CR in there (and can get it back if I stick a long burn in there).
-Baffle! This thing has a full body stuffer tube and multiple centering rings, so why not try something new! (something I try and incorporate in all my builds) More on this as it develops.
-Adjustable noseweight! Callback to longer motors, this thing is -by reputation- a squirrely flier. Will feature rivets (of course) or 3D printing (possibly both!)
-Nail down the CP! I would like to have some numbers behind my motor selection and weighting scheme.

Stay tuned!

 

[Nytrunner]

On to building: Analog and Digital....

I've already learned something on this build: I've been using the wrong wood filler.....
I bought Stainable wood filler that contains wood fibers. For several rockets I've been thinking, "I don't understand why people say this is so easy..." or "Man I suck at this".
Way easier with the right stuff. You can see the difference between the two consistencies on that 1st tube. I'm going to keep the Stainable stuff for filling gaps. Now all the barrels, the forward tube, and the two gaps in the central have been filled and sanded.



The fins......
These 3D prism fins are friggin challenging. I discovered that my superglue had gone bad, so instead of tacking with a couple drops and leaving the titebond to dry, I spent ~15 minutes watching Smallville and holding each piece's first joint until it set to the point where I could prop it up and leave it. Once that first joint is dry, they're actually pretty strong (maybe there's truth to this "triangle is the strongest shape" business). I'm taking my time on these. You can see one piece drying the first joint, another with its back strip and internal brace, and the third complete. (by the way, these are just the rear HALF of the fins....)


I'm holding off on gluing the barrels to the long tube until I get the retainer. I don't have the recessed length dimension of the retainer, and I want to make sure every thing fits well the first time. In the mean time, I'm using solidworks to build it in the virtual world. Just like my Broncbuster II thread, I'm going to perform a similar airflow analysis to try and pinpoint (interpret: take an educated guess at) a good CP location. Modeling this thing is allowing me to learn my program better too. That ridged nosecone and the prism fins are making me come up with weird tricks and reference geometries to try and get this thing accurate. (I'll have better fin dimensions once the parts are dry. Those are just for practice)

 

[rstaff3]

Very cool, can't wait to see more!

 

[Rex R]

if it is taking 15 minutes to tack up(glue), you're using too much glue. should take a minute or less to tack up. I did all 4 fins of a big bertha in 5 minutes.
Rex

 

[Cabernut]

Good luck! I can already see why it's a skill level 5. Looking forward to this one.

 

[neil_w]

op:

 

[Nytrunner]

if it is taking 15 minutes to tack up(glue), you're using too much glue. should take a minute or less to tack up. I did all 4 fins of a big bertha in 5 minutes.
Rex

Entirely possible. I'm by no accounts a glue-master, and occasionally get extra splurge from the bottle tip.
I have better times and success placing conformed fins straight on a tube. The problem I ran into here is that the long edges have to remain unbeveled and touch corner-to-corner leaving a shelf for the backing strips. That's a pretty tiny contact area. On each fin I used successively less glue, and, from my perspective, the last one took the longest to hold. The slotted "A" piece held together pretty quickly, but the ends of the long edge kept wanting to separate.

Very cool, can't wait to see more!

Good luck! I can already see why it's a skill level 5. Looking forward to this one.

op:

Thanks all (and Rex )!

I'm predicting there will be some Agk moments along the way. Like I realized after posting last night that holing the forward centering ring for a baffle will be difficult since it is.....already glued into the forward barrel. I'll have to get creative with an xacto knife or buy a loong 1/8 drillbit.

I'll try and take better pictures too. These were just snaps to show my girlfriend what I'm up to.

Question for the scratch builders or "kit improvers":
how often does "Wow! This is a great idea that'll make this way better!" become "Wow, this is a lot harder than I thought... I did not think this through when I started"?

 

[Cabernut]

...
Question for the scratch builders or "kit improvers":
how often does "Wow! This is a great idea that'll make this way better!" become "Wow, this is a lot harder than I thought... I did not think this through when I started"?

All the time.

 

[Nytrunner]

Just glued the shell on the last of the rear "fin" halves and set it to dry while applying some leftover spiral filler to seams in the other two. Those barrels make wonderful impromptu drying holders. Retainer hasn't arrived, so no tube gluing yet.

Shown is the balsa negatives for he rear set. That's 7 pieces each.


Planning out the Forward halves, it looks like they'll hold together during gluing much better than the rear 3. The fully enclosed slits make things lock better than the open spaces of the previous set (visible in the balsa skeletons above ^^). There's one more tiny diamond piece that reinforces the "elbow" of each fin assembly. Which makes one Entire fin assembly 12 pieces in all. How many are in the intakes on a QCC Explorer?

In the picture is a TBII bottle and a standard xacto knife for scale. Seriously, just looking at the catalog gave me no indication of this thing's size. It would be way harder if it was smaller that's for sure. I'll leave the downscaling to those that enjoy building rockets with tweezers.


Looking further ahead, I'm debating using a 3D printed twist lock for the nose to adjust weight, or just using rivets (woo!). Advantage of twist lock is that its fully internal and customizable and I could move the rivets down to the transition so I can service the shock cord. Advantage of rivets is that I already have 96 of them and wouldn't need to go find a print-vendor that doesn't overcharge....

Which reminds me, I'm kinda changing up the body split. Instructions call for holes drilled in the transition to pass the gas forward and pop the nose. I'm going to put a Chute Release in there, so no holes will be drilled, and the split will be at the transition base.

Included is a close up of the nose because I recall hearing about while discussing the Blackstar on K'Tesh's OR file thread. It looks like a unique Estes offering with 12 flattened strips equally around the circle.

 

[JumpJet]

The Prototype flew many times just fine without the extra holes being drill in the front of the Plastic Transition piece. I later added a nice finish to it and it is now hanging in the Museum of Flight in Washington state.

For anyone out there that is wondering if the holes are really needed, assemble the upper portion of the model with tape and simply blow through the engine tube. The nose section should pop off very easily.

John Boren

 

[Nytrunner]

Thanks for the info John!
Never thought my mutilations of one of your most-eyecatching designs would warrant your attention.

Since you're here , can I ask how you approach such non-traditional designs? Does Estes use CFD or a tunnel, or just experience and a string test?
Adjusting features until it flies consistently.

I never knew there was a model rocket historic museum piece! If I'm ever there I'll have to check it out.
(and there's even an article about it on my club's website.....)
https://hararocketry.org/hara/narcon-dedicates-model-rocketry-exhibit-at-museum-of-flight/

So the flow through the cord loop on the transition is sufficient for standard deployment? Cool

Unless I can fit a Chute release in the forward section, I'm probably going to stick with my plan to fix the nose in position and split behind the transition. I'll just have to make sure the chute pulls the forward half as farrrr away from the back as possible.

 

[JumpJet]

just experience and a string test?

I'm the only one at Estes that designs our kits except for two that were design my Mike from Hobbico a few years back.

I just build models and test fly them. Only the REALY strange ones some times go unstable and those I expect it to happen too so they are heads up flights. The Black Star Voyager is most likely my favorite sport model I've design for Estes. It flew great the first time it was flown but I added clay to the nose just to be safe.

John Boren

 

[Nytrunner]

Well that doesn't at all make me more self-conscious about this build :blush:

The retainer isn't here yet. They're taking a bizarre shipping scheme which apparently includes being transferred from UPS to USPS(?) in....Marrow GA
This is the best guess I've been able to make from cryptic shipment updates. Kinda overshot huntsville by 100 miles or so.


Spent this evening doing laundry and cooking, so I yook a departure from the physical build to work on the 3D model. Adjusted the pyramid pylon dimensions to match my completed rear fin halves and added the arms. I'm making this model as a single piece, so a bunch of reference planes have been necessary in addition to the 3 principles.
(Circular Pattern tool is my lifeline here). It could be a bit simpler to make the pieces as individual parts, but that just defers the challenge to when I need to mate them together, and when it comes time for the Flow-analysis, I'd prefer not to have to hunt down gaps and spend a couple hours checking for water-tightness. A single piece flow geometry simplifies things greatly down the road.


Also spaghetti is a great sanity mender. I highly recommend it as an add-on for any Skill-5 build.

 

[TangoJuliet]

Subscribed. op:

That's not nearly enough spaghetti!

 

[MALBAR 70]

The Prototype flew many times just fine without the extra holes being drill in the front of the Plastic Transition piece. I later added a nice finish to it and it is now hanging in the Museum of Flight in Washington state.
John Boren

That's THE prototype?! I feel honored to have laid eyes on it. If you are ever in the Seattle area I strongly suggest visiting The Museum of Flight and the awesome model rocketry exhibit there.

Nytrunner, keep up the nice work (real and 3-D). I'm looking froward to seeing this finished.

 

[BDB]

Subscribed. I really want one of these kits, but I can't justify buying it until my build pile gets a little smaller.

 

[Nytrunner]

Subscribed. op:

That's not nearly enough spaghetti!

Good to have ya along! You don't know how big my plates are.
See, my eyes tell me you're right, but my post-college stomach says "Do you want to go to the gym and work off two extra plates of spaghetti and meatballs, or do you want to finish this Black Star Voyager before summer!"

That's THE prototype?! I feel honored to have laid eyes on it. If you are ever in the Seattle area I strongly suggest visiting The Museum of Flight and the awesome model rocketry exhibit there.

Nytrunner, keep up the nice work (real and 3-D). I'm looking froward to seeing this finished.

I really want to go check it out.Maybe I can sneak mine in and take a picture with both of them!

Subscribed. I really want one of these kits, but I can't justify buying it until my build pile gets a little smaller.

To keep this a hobby and not let it become a list of undone things, I've imposed a limit of 5 unbuilt kits on myself. With this one in progress, I've only got three in the bag now, so I may throw an order at AC supply company soon.

 

[Nytrunner]

I'm not sure if its the titebond or the fit of the rings in the barrels, but a couple of the rings seem to have taken on a very slight convex shape. Not predicting a problem, just puzzled.


On to the forward half-set:
Here's a close-up of the long joint. Not a exactly luxurious amount of contact area at the tips. Fortunately, I was right, the slotted piece helped these hold together much better than the rear set.



I wanted to mock up a complete fin assembly just to see what it looks like in person. TBII bottle and xacto make another appearance as scale references (I may have to make that a regular thing). Honestly, I probably ould have glued another forward half in the time it took to get this balanced long enough to take the picture. It is definitely necessary to do some sanding at the tube/fin interface.

Once the halves and brace are glued, there's a .15" wide strip of 1/16" balsa that will get sanded into a sharp edge (LE missing in above pic, TE present). Lets just say I'm going to take a pass on any attempts to airfoil this build. l'll leave the extent of my meddling to the internals and retainer.

 

[TangoJuliet]

Good to have ya along! You don't know how big my plates are.
See, my eyes tell me you're right, but my post-college stomach says "Do you want to go to the gym and work off two extra plates of spaghetti and meatballs, or do you want to finish this Black Star Voyager before summer!"

Well, I'm in my middle years, and I have to work out about 12 days a month just so I don't age too quickly, but I'm a pasta lover so it's difficult not to gorge myself with it! In fact, I ate a huge bowl of it last night. My girlfriend said it was supposed to be two servings . She has also imposed a limit on my stash until I get more kits built/finished. Unfortunately, she's right.

 

[Nytrunner]

The easier part of the fin halves are done and dried overnight. Adding those to the barrels I think I've got ......an unassembled Skill 3 rocket now? Possibly a 4 depending on how much sanding is needed and how hard finishing is.

 

[Daddyisabar]

Question for the scratch builders or "kit improvers":
how often does "Wow! This is a great idea that'll make this way better!" become "Wow, this is a lot harder than I thought... I did not think this through when I started"?

Sometimes the Mindsim requires more than just a kit bash, it requires a full on kit spanking. You know you are in huge trouble when see the child's plastic ball at the toy store and think "That would make a nice addition to the Blackstar Voyager to make it look more like the Krenim Timeship." What will the mid mounted ball do to the CP? Yes, I can see it in my mind flying on one of the punchy CTI 24mm motors. Farewell Skill Level Five, it was nice to know ya. In the end the only hard part is getting past the RSO table.

 

[Nytrunner]

Sometimes the Mindsim requires more than just a kit bash, it requires a full on kit spanking. You know you are in huge trouble when see the child's plastic ball at the toy store and think "That would make a nice addition to the Blackstar Voyager to make it look more like the Krenim Timeship." What will the mid mounted ball do to the CP? Yes, I can see it in my mind flying on one of the punchy CTI 24mm motors. Farewell Skill Level Five, it was nice to know ya. In the end the only hard part is getting past the RSO table.

In the year and a half that I've been reading things on this forum, NOTHING I've read has struck more engineer's terror in me than the word "Mindsim"......


No sphere's will make their appearance in this build. I'm hoping the only external change will be the retainer and a rivet-hump or two.

Although, Once I'm through with the original model's simulations and analysis, It will be trivial to stick a Big-ol-Ball on the digital model and see how big a difference that makes with the CP!

 

[rstaff3]

In the year and a half that I've been reading things on this forum, NOTHING I've read has struck more engineer's terror in me than the word "Mindsim"......


No sphere's will make their appearance in this build. I'm hoping the only external change will be the retainer and a rivet-hump or two.

Although, Once I'm through with the original model's simulations and analysis, It will be trivial to stick a Big-ol-Ball on the digital model and see how big a difference that makes with the CP!

If you don't need a mindsim, your model may be too conventional. Although I try to back my mindsims up whenever I can with actual sims, faked-out components in actual sims, phantom cones, neutral points, cut-outs and swinging tests. Maybe we should rename the term to 'alternative stability".

 

[Daddyisabar]

Putting a ping pong ball, or a foam ball, or a plastic ball on a tube always makes the rocket cool. Just an embellishment here and there. No engineering skill required. Nose weight and a bigger motor cures most embellishments. No fear when you do build that Timeship!

 

[neil_w]

I think we can probably say that John B's original model was primarily mindsimmed. In which case his mindsim is operating at a much higher level than mine.

Of course, rocket wise, his everything is pretty far above mine.

 

[Nytrunner]

If you don't need a mindsim, your model may be too conventional. Although I try to back my mindsims up whenever I can with actual sims, faked-out components in actual sims, phantom cones, neutral points, cut-outs and swinging tests. Maybe we should rename the term to 'alternative stability".

I've just got to put some numbers behind things when I have an idea. Like with the induction rockets and flow analysis. Any opportunity to validate an idea is an opportunity to save time and money on testing.

This reminds me of one of the "unwritten rules of rocketry" I read while interning at a certain private spaceflight company that shall go unnamed: A solution without analysis is an opinion. A solution from poor analysis is a Bad opinion.

I think we can probably say that John B's original model was primarily mindsimmed. In which case his mindsim is operating at a much higher level than mine.

Of course, rocket wise, his everything is pretty far above mine.

That's why I don't want to change the geometry of it. Like turbocharging a 70s Chevy, the inside is all new but the outside is what makes it a work of art. What gives it its spirit.

Putting a ping pong ball, or a foam ball, or a plastic ball on a tube always makes the rocket cool. Just an embellishment here and there. No engineering skill required. Nose weight and a bigger motor cures most embellishments. No fear when you do build that Timeship!

I still need numbers. I don't want 1/10 of an oz more than is necessary, and perhaps I have the arrogance to think with the proper preparation I can get it right on the first try.

Of course there are cases like my inductor rocket that keep me just humble enough to be tolerable. The math for that one needs some polishing.

 

[Nytrunner]

The retainers finally came! My one use of epoxy will be to get it in place on the end of the main body tube. I seem to have several spent motor casings around these days, and they are turning out to be unexpectedly useful,



I'm also getting better applying TBII out of that slot tip. I'm slightly proud of that little bead pre-spreading. The aft 2 barrels are now drying happily, and I'm about to mount the third one.


What used to be the motor tube of the central BT-20 has now been cut down to fit the Chute Release. My initial thoughts for a baffle were to seal the end of the central tube, cut holes in the sides, then perforate the forward centering ring in the barrel. Since that ring was already mounted, I took a different gas redirection scheme.

I have a bunch of ring blanks with mini fin cut outs, so there are now two of those glued inside the central tube, with balsa squares in between, and finally two offset shelf-like pieces at the end. So thats about 4 " of twists and turns for the gas to take.

 

[Nytrunner]

Back to fins:

I've probably mentioned before, I have little faith in wood that I can cut with my fingernail. That being said, balsa is wonderfully easy to sand into shape! The LE and TE backing strips on the fins weren't that hard to sand down flush and shape into a nice rounded ridge.



After a little tip work, I've matched up and numbered fore and aft pieces that mate together well at the elbow. Tomorrow will hopefully see the bases sanded down so they meet the tubes.


The tube is marked with 9 lines for fins and all these fiber decorative pieces. I got to say, now that its glued together, it really feels solid! Stick a motor in the end and I've got to resist the urge to try smacking someone upside the head with it (not that it wouldn't bend or dent in some way if I did)
Here's a question: Has anyone noticed Estes fin placement guides overlapping too much on the tubes? I measured the distance between the 1st and last lines and it was shorter than the others, so I indexed the guide in order to maintain the same distance between pieces. Printer scaling issue perhaps? I ran into the same thing with the Scion fin guide I had (before I tossed it and made my own for a leviathan)

After I sand the fin bases tomorrow, I'll start the long process of attaching these 27 detail pieces. A nifty placement guide is included (upper left of picture). Its designed to hold a piece against the BT-20 and maintain 40 degree spacing with its neighbors.

 

[Nytrunner]

Gluing continues inbetween house tasks this morning.

I wrapped 160grit sandpaper around the tube to shape the fin bases. You have to give a hand to the designer because it doesn't take much sanding to get these pieces fitting together well.



The teeny finlets and detail pieces are going steadily. 9 down, 18 to go.

 

[Nytrunner]

Played basketball yesterday, discovered I was exactly as out of shape as I thought. But I did get more pieces on.



Spent most of today at Manchester field watching SLI teams prep, seeing students certify (Great success with the L1's. L2's.....not so much), and sending launching a couple myself (details in BroncBuster II thread)

Got back home, had to prepare for work and was pretty tired from ball and trudging around a soggy sod farm. No physical progress, but the digital is ~95% complete. Just have to form the retainer on the Aft end. I don't know anything about applying graphics in Solidworks, but I can use a color palette.

Thought some views with the original Black Star colors would be cool.
Just have to figure out some flight velocities and the flow cases can start running.