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frogglicker

Well-Known Member
TRF Supporter
Joined
Feb 10, 2023
Messages
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Location
Centennial, Colorado
Intro:

Over on another thread in the 3D Printing section, there's a friendly competition going on: TRF Challenge #1: Estes Menace and I thought this would be a great opportunity to push myself to learn more Fusion 360.

I started back in March 2023 to 3D print small parts, and started designing in TinkerCAD which really helped me get my designs to the printer, faster. There were just some things that were not easy to do. I tried OnShape and had some success with that, building simple nosecones, fins, and centering rings but I still struggled with some other things, like knurled textures for retainer caps or threads. There is nothing wrong with either app and everyone will come at this activity with different perspectives. For me, Fusion360 just seemed intimidating, so I kept putting off learning with it.

It's a great tool for me now and I can do all thing things that I wanted to do, so when this challenge presented itself, I got right to work. This thread will document the build along with the final launch performance against the simulated design.

NOTE: All the designs were done against LOC/Precision tubing (Body and MMT). I have failed to make this distinction in the past, and caused some people using my designs some bit of grief. My sincerest apologies for that.

Design:

The challenge presented by @cwbullet did not have a readily available OpenRocket/RockSim file. I wanted to build something bigger but I needed a frame of reference, so I found some scans on JimZ's website and some details on RocketReview.com that allowed me to put together a rough OR sim at scale. I didn't have specifics for the fins or intake, so I eyeballed them. Once I was happy that the sim roughly resembled an Estes Menace, I scaled it up and started tweaking. The forward fins seemed a bit too narrow, so I gave them a more triangular shape. The aft fins seem a bit small, but the sim showed stable flight once I completed the design. I created an Ogive nose cone but I may have overcooked my grits with that. However, the design "Looks" really good.

With the nosecone, it was way bigger than my printer would allow and cutting and gluing parts together is not something that I enjoy. I wanted to do something with threads, so I build a 2 piece nosecone similar to Arogen67's Big Red Max nosecones. I loved this design but it didn't work out well for me because it was too thin. I created beefed-up versions and put them on Printables, but the idea of creating them from scratch was beyond me. Time to fix that. I also love IPL's nosecone ebay and I have exclusively adopted this for my rockets, where applicable. There were some things that I wanted to modify, so I originally took the same approach and remixed the original. For the Menace, I have redesigned both the nosecone, shoulder coupler and the nosecone sled from the ground up. The thread pattern on the ebay sled was engineered so that it would work in both my existing designs and this new one, so I have backwards compatibility.

For the intake, I took the aft fin and used it to get a rough idea of the shape. My first prototype looks much like the others and that is fine and functional. Being a Sci-Fi geek, I like long, fast-looking designs so I stretched out the leading vertical supports to an exaggerated amount. I will often do this then reel it back into something more sane but the look really had a Star Trek vibe and I liked it, so I kept it. The forward fins also deviate from the original but I think that they look good too.

I was curious about motor retainers that have a flange to hold the threaded ring on the the back of the rocket. I realized that I could design it so the flanged ring doesn't need to be epoxied rather, it can be mechanically fastened. I designed a 38mm retaining ring with flange and companion cap that should be able to take the abuse from the hot and hairy end. Also, if they burn up, I can replace them and get back in the game (theoretically).

I also created centering rings of various types. One as a mate for the flanged retainer, a flat one, and one with two holes. All the holes for this model are either 3mm or 6mm. For the CR to mate with the retainer, I plan to use 3 or 4mm heat-pressed inserts then I can use the same machine screw with some Loctite.

Pre-build:

Before I can build, I need to print out the parts. I elected to prep the parts from Fusion360 (saved as .3mf files) using OrcaSlicer, since I like that you create multiple plates and it integrates my Klipper UI so I can slice, print, and monitor in one environment. PrusaSlicer has been my main slicer and since Orcaslicer is a fork, they are nearly the same. OrcaSlicer just has some quality-of-life features that I like.

The nosecone, centering rings, and retainer were printed in PETG. I printed the fins and the intake in PLA+ (because I ran out of PETG). Though, I didn't really have to, I printed everything 100% infill. They are just a bit bigger than the perimeters that set (6), so it really isn't much savings unless I go with 5%. It makes me happy. The fins and centering rings are 6.3mm thick. I was able to design and print everything in a weekend, as I would design one part, then print it and start on the other while the first was printing.

I took a break from designing parts and switched over to the Cricut to design the decals. I have a few different methods for doing this. If I can find a decal scan, I will convert it to SVG and port it into Cricut Studio. Often times, the quality is garbage, so I go hunting fonts on 1001fonts.com until I find something close. I can usually reproduce designs in PaintShopPro pretty close, like on my Mega Red Max. Once I imported the decals, I noticed most were pretty decent with only a few too small or not good enough. This isn't scale and my designs are definitely not in the accuracy ballpark, so I left some out.

Build Part 1:

And now we are caught up. Today, I started laying out the fins and centering rings. I designed a fin slotting jig and that was really helpful. It was designed for the aft fins but helped with the forward fin slots. I did goof up by not drawing a centering line down the tube and the forward slots were off. I also cut 4 slots for the forward section when I got distracted and forgot what I was doing. I had an extra tube so it was not catastrophic. the fins fit perfectly in the slots, but for some reason the fin tabs are short. Not sure what happened as I translated the values from OpenRocket. now I need a solution for that (did someone say 'Print something'?)

Once I get a solution for the tabs, I will begin glue-up. I will not be gluing in the forward or aft CRs so I can get the goop on the tabs but I will insert them to keep the MMT centered then pull them out for epoxy.
Fixes:

I will need to design a solution for the tabs. I have an idea that might work. If it pans out, I will share it. If it doesn't, then it will never see the light of day! J/K. I document my wins and fails so others can learn from me. I'm just a walking cautionary tail. I will also modify the intake to take off the excess on the aft end so its flush. The fin slot is tailor fit for the fin round-over and angle, so I just need to get some measurements and lop off the excess.

That's it for now. Below are a bunch of pictures with captions. I will continue to post as I make progress. I am hoping 🤞to launch this this weekend on an H250. It will be a straight shakedown flight, then I will add the electronics for DD.

The Big Nuke Duke'm was supposed to be my DD practice rocket, but since I have something just as cool and capable, The Menace will do nicely. Once I'm confident with the DD, I will start looking at 38mm I motors. Once the contest is completed, I will post all the .STLs, .3mf, and CAD drawings for anyone to use as they will.

Thank you for reading.
1707791977183.png
The Menace-3D Concept

1707791600874.png
OpenRocket Design

1707790083128.png
Slicer Layout after Design
Menace 3D.jpg
Parts are Printed (mostly)
Screenshot 2024-02-10 212714.png
Decal Design for Cricut
20240212_142419.jpg20240212_144816.jpg20240212_151133.jpg
Fin Slotting Jig Aft Fins Done Marking for Forward Fins (with blood sacrifice)

20240212_145214.jpg20240212_145219.jpg
Dry Fit the Intake to Aft Fin Intake Overhangs by about 8mm 😢

Final Mockup.jpg
Final Mockup
 

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I fixed the Intake last night. It was 9.7mm too long, so I shortened it and also conformed the bottom to a 3" tube. It should sit nice and flush now. I made a boo boo trimming the MMT. I trimmed it per the plan but its too short to hold the rings for the forward fins. I'm working on a solution to fix that. I will NOT be flying a motor big enough to reach up there and this is my DD practice rocket, so motor ejection isn't really a concern.

Had a couple print fails (filament got wedged in the spool), so I'm just now in the middle of the reprint. I'll have to check it tomorrow.

1707882088354.png 1707881989148.png
Print Status Redesigned Intake
 
After the intake print failure two nights ago, my printer hasn't been happy. I went through all the axis points and snugged up the bolts, loosened and retightened the belts (no lube), then recal'd the printer and resliced the model with 10mm brim. This resulted in an epic win! Because I am ADHD, I feel like a checklist is in order, so I am building that. I also have some minor design tweaks to perform to the design but they wont alter the overall design.

I designed a MMT tube coupler to fix my miscut and it turns out that its the perfect size to bridge the gap on the fin tabs. I'll rough up the surface for epoxy to give it some bite and keep pressing forward. My goal today is to get the CRs on the MMT and epoxied. If I have time, I'll get the MMT mounted in the body tube.
 
I've been through a few iterations on the Menace 3" Finbay. What I am trying to solve:
  • Provide a solid mounting platform for the FWD fins
  • Have an optional ebay within the body tube
  • Still allow for larger motors yet retain a payload space for avionics
I think this design checks most of the boxes.

The original design includes my typical ebay in the nosecone. That will work with standard motor or electronic ejection. While the JollyLogic chute release is a type of dual deployment, I am working on traditional drogue/main configurations. The problem with my original design had the MMT going up through the body past the FWD fins so they could attach. There is nothing wrong with this design, it just seemed off to me and stalled my build until I came up with a solution that made sense to me.

This new option allows me to attach the fins to a can that is a segment of the body tube vs a coupler. It gives me a bit of room and serves multiple purposes. This will make more sense with pictures.

Here is the Menace as designed back in February:
Screenshot 2024-02-06 062216.png
Original Design

The idea now is to separate the tube before and after the FWD fins and replace it with this:
Screenshot 2024-07-09 185430.png
Finbay Concept

1720834101464.png
Initial OR with Menace with FinBay loaded with an I80 Motor

(I realize that this OpenRocket design still needs some tweaking. There isn't enough room for a drogue and shock cord -- This build thread is my interactive psychosis at work)

In addition, I thought about designing a sled and bulkheads. I went through a couple of iterations and finally came up with this:
Screenshot 2024-07-12 071416.png
Latest Finbay Iteration




The first plate has all the parts for this option:
  • Finbay tube with slots for the fins
  • Finbay tube without slots (for versatility)
  • Ebay sled unattached
  • Ebay sled attached to a bulk plate
  • Fin
  • Bulkhead
So, this allows me to use the design on other projects. Since the Menace FWD fins are so far back, larger motors would interfere with the Finbay with electronics in it, so I can move the electronics to the nosecone, and this acts as a pass-through.
The sled options were just for versatility to see if I liked connecting one end to the bulkhead. I think the floating sled suits me more than the attached option. The fins are a perfect fit to the slots, with just enough clearance to not starve an epoxy joint, yet not sloppy. After a few hours of pondering, I think the best solution for me is to use the sled configuration on plate two with the tube/fin combo on plate three.

However, this introduces a new set of problems:
  • How do I secure the finbay to the tubes
  • How to prevent the aerodynamic torque from ripping the finbay away from the rest of the rocket during boost
So, I've been thinking about these issues and came up with some ideas.

First problem's solution: secure the finbay to the tubes with heat-pressed inserts. This will allow me to use screws or nylon bolts to secure the tubes to the fincan similar to rivets and shear pins. I think the short, 4mm inserts would work with 3 or 4 around the diameter.

Second problem's solution: Without some reinforcement on the body tube, the screw may rip through the tube. However, if I reinforce the tube with a small ferrol, this would interface between the body tube and the screw. I'm just concerned about a nylon bolt being strong enough to withstand the wind resistance on the fins during boost yet be able to shear during deployment without having to use enough BP to blow the fincan section to pieces. Since I am thinking of 4 hard points to attach the bolts, I can ground test to find the strongest bolt combo to keep everything together and the best BP charge to separate the parts and keep everything in one piece. I am looking at the guitar ferrols for through-the-body string guides or simple brass/copper tubes with a 4mm ID will work

I don't know if this will work. I might just epoxy the fins to the finbay, use it as a pass-thru, and keep the electronics in the nosecone, or this might just fold up into a giant fiery mess. Any number of things can go wrong. While this violates the Keep it Simple axiom, I'm designing solutions for problems, learning about aspects that I haven't explored before, and having fun.
 
I've been through a few iterations on the Menace 3" Finbay. What I am trying to solve:
  • Provide a solid mounting platform for the FWD fins
  • Have an optional ebay within the body tube
  • Still allow for larger motors yet retain a payload space for avionics
I think this design checks most of the boxes.

The original design includes my typical ebay in the nosecone. That will work with standard motor or electronic ejection. While the JollyLogic chute release is a type of dual deployment, I am working on traditional drogue/main configurations. The problem with my original design had the MMT going up through the body past the FWD fins so they could attach. There is nothing wrong with this design, it just seemed off to me and stalled my build until I came up with a solution that made sense to me.

This new option allows me to attach the fins to a can that is a segment of the body tube vs a coupler. It gives me a bit of room and serves multiple purposes. This will make more sense with pictures.

Here is the Menace as designed back in February:
View attachment 656046
Original Design

The idea now is to separate the tube before and after the FWD fins and replace it with this:
View attachment 656047
Finbay Concept

View attachment 656027
Initial OR with Menace with FinBay loaded with an I80 Motor

(I realize that this OpenRocket design still needs some tweaking. There isn't enough room for a drogue and shock cord -- This build thread is my interactive psychosis at work)

In addition, I thought about designing a sled and bulkheads. I went through a couple of iterations and finally came up with this:
View attachment 656024
Latest Finbay Iteration




The first plate has all the parts for this option:
  • Finbay tube with slots for the fins
  • Finbay tube without slots (for versatility)
  • Ebay sled unattached
  • Ebay sled attached to a bulk plate
  • Fin
  • Bulkhead
So, this allows me to use the design on other projects. Since the Menace FWD fins are so far back, larger motors would interfere with the Finbay with electronics in it, so I can move the electronics to the nosecone, and this acts as a pass-through.
The sled options were just for versatility to see if I liked connecting one end to the bulkhead. I think the floating sled suits me more than the attached option. The fins are a perfect fit to the slots, with just enough clearance to not starve an epoxy joint, yet not sloppy. After a few hours of pondering, I think the best solution for me is to use the sled configuration on plate two with the tube/fin combo on plate three.

However, this introduces a new set of problems:
  • How do I secure the finbay to the tubes
  • How to prevent the aerodynamic torque from ripping the finbay away from the rest of the rocket during boost
So, I've been thinking about these issues and came up with some ideas.

First problem's solution: secure the finbay to the tubes with heat-pressed inserts. This will allow me to use screws or nylon bolts to secure the tubes to the fincan similar to rivets and shear pins. I think the short, 4mm inserts would work with 3 or 4 around the diameter.

Second problem's solution: Without some reinforcement on the body tube, the screw may rip through the tube. However, if I reinforce the tube with a small ferrol, this would interface between the body tube and the screw. I'm just concerned about a nylon bolt being strong enough to withstand the wind resistance on the fins during boost yet be able to shear during deployment without having to use enough BP to blow the fincan section to pieces. Since I am thinking of 4 hard points to attach the bolts, I can ground test to find the strongest bolt combo to keep everything together and the best BP charge to separate the parts and keep everything in one piece. I am looking at the guitar ferrols for through-the-body string guides or simple brass/copper tubes with a 4mm ID will work

I don't know if this will work. I might just epoxy the fins to the finbay, use it as a pass-thru, and keep the electronics in the nosecone, or this might just fold up into a giant fiery mess. Any number of things can go wrong. While this violates the Keep it Simple axiom, I'm designing solutions for problems, learning about aspects that I haven't explored before, and having fun.
Love it.
 
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