Quantcast

Basket Case 2 - 3D Printing + a K535 = awesome

The Rocketry Forum

Help Support The Rocketry Forum:

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Hi everyone,

I built and flew the rocket I called "Basket Case" at Mini-Midwest Power last year. It was the furthest up the power ladder I've gotten into 3D printing, a dual-deploy 3" that flew on a J450DM (pics below). The thread for that one was here: https://www.rocketryforum.com/threa...-and-glass-practice-prior-to-l3.155453/page-4

The original goal there was to build a dual-deploy rocket to check that box going into L3 (had done dual deploy over a decade ago, needed a refresher). My L3 rocket is about 2/3 done, but given I have a kid on the way in June, I'm paring down big + expensive rocketry activities for this year...if I get to it in 2021, great, if not, I have more experience going into it in 2022. I already have everything I need for this launch (motor, printer filament, flight computers, etc) so this build is basically "more dual deploy experience flying on money already spent"...fits well with my current life situation.

There were a few things about that design and launch that I want to improve on. In no particular order:

1) The fins in the original configuration were way too big and the rocket weathercocked HARD on a not particularly windy day. Fins are going to be chopped down. I overdid it on stability (something like 4.5 calibers), going to cut down on that some.
2) The nosecone was stubby due to limited height on the 3D printer. Since then, I've learned how to attach two prints together and will be doing so here so I can print the nosecone in 2 or 3 pieces to make it longer.
3) Changing filaments to PETG (using recycled PETG from GreenGate3D.com - the owner is a friend of mine and all around great guy, want to show him what is possible with his filament).
4) There were no video cameras on board, which I've since discovered is great fun. Current plan is to have 2 on board, one looking sideways and one down.
5) Use an actual drogue chute and have it deploy properly instead of the crap streamer that got tangled on the first try.
6) Bonus points - push it to a mile up (going to take a lot of lightening to make it happen)
7) I procrastinated pretty hard last time, ran out of blue filament, and ended up needing to add grey and white to it. This time I'm getting a couple of 3kg spools a few months ahead of schedule.


Basket Case 1 (everything blue is 3D printed):

Resized_20200519_215311.jpeg



BasketCase.jpg
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
This camera will be looking sideways out the side of the nosecone: https://www.amazon.com/RunCam-4K-Xv...coding=UTF8&psc=1&refRID=HGQFHM56KY09NPPK76XJ

This camera will be looking down, probably mounted to the top of the fin can (the blue ring on the 6" above the fins):

This is the first take on the stretched nose cone, total length 535mm. The square cutout is for the top video camera link posted.

Nose Cone.PNG
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
353
Reaction score
147
Location
Indiana
Nice work man and good luck on the next step!
Was the fin can a single print?
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Nice work man and good luck on the next step!
Was the fin can a single print?
Thanks!

Yeah, fincan was a single print. 7 or 8 days I want to say. Good times, lol. The tailcone formed the motor retention too, the tailcone bolted onto the bottom of the fincan looked aaaaweeesome.

Resized_20200519_215338.jpeg
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Completed the tweaks to the fincan. Made the fins quite a bit smaller and changed the angle on the bottom so they should print without support. One of the things I LOVE about 3D printing fincans is that it's easy to do a taper from root to tip, makes the fins super stiff.

Fincan.PNG

Fincan 2.PNG




I also designed a camera "pod" that will attach to the side of the fincan opposite the rail attachment point. Here's the top and bottom showing what goes where:
Camera Pod 1.PNG


Pod Annotated.PNG


Idea being it can be assembled offline, attached to the airframe only if desired, and is turned on with just a single screwed Missileworks switch.


This is what it looks like put onto the fincan:
Pod on Can.PNG




The av bay and whatnot will remain the same as the last one...only I'm changing from running 4 9V batteries to 8 1S Lipo's. Will be pretty simple to incorporate actually.
 

Attachments

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
353
Reaction score
147
Location
Indiana
You do some really great work, I’m jealous what print bed size do you have to work with
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
You do some really great work, I’m jealous what print bed size do you have to work with
Thanks! Stock CR-10, which is 300 x 300 x 400. I have plans to build a 500 x 500 x 800, want to be able to print a monolithic fincan that can take an M. That's a couple of years off though.
 

Bruce

Well-Known Member
Joined
Feb 21, 2019
Messages
130
Reaction score
17
Nice Rocket!

What about 3D printing the tubes?

It seems like the payload sections could be done reasonably easily.

And maybe the recovery section could be designed so that the parts that get worn from the ejection gasses could be periodically replaced?
 

HHaase

Well-Known Member
Joined
Aug 3, 2014
Messages
788
Reaction score
209
Mother F......
I'm impressed and inspired.

-Hans
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
What upgrades have you done to the cr10 to print petg
Nothing remarkable. I have a Bondtech extruder (dual gear drive thingy) but I don't think that has a huge impact. Capricorn tubing. TH3D mainboard after the stock Creality one fried. I had an E3D V6 hot end on it but I was getting clogs all the time and went back to the stock one and have been doing OK since...not perfect, but better. Thinking about putting a Slice Engineering Moquito on it at some point.

At the end of the day, the stock setup should work with PETG. I print mine at 238°C, the stock hotend goes to 245°C without issue, so there isn't a problem there.

Oh, and I have a magnetic bed also from TH3D. Their textured PEI thing is the *perfect* amount of adhesion for PETG.


Nice Rocket!

What about 3D printing the tubes?

It seems like the payload sections could be done reasonably easily.

And maybe the recovery section could be designed so that the parts that get worn from the ejection gasses could be periodically replaced?
Thanks!

I've tried printing tubes, have done so for up to D motors. Short version is that in order to have enough impact resistance to be flyable more than once, it needs to be thick. Thick means really heavy. So, I'm sure you could print tubes that you could fly an M with...but it's gonna go about 2k feet and possibly shatter when it hits the ground. Rocket-oriented tubes (fiberglass, CF, or glassed cardboard like here) are more durable, lighter, and cheaper.



Mother F......
I'm impressed and inspired.

-Hans
Thanks! Glad I could do so!
 

3stoogesrocketry

Well-Known Member
Joined
Feb 26, 2012
Messages
1,333
Reaction score
155
Before you reduce the fin size , I'd hit the rocket off the pad faster. From your picture , the rocket is already leaning to the left no more then a few feet off the rail . With all due respect , your fins are not acting as fins yet. Being over stable is more of a faster issue then a slower issue . I would use a motor like your K535 that has alot more impulse off the pad , or even step it up to a J800. Based purely off looks , your fins look just fine on revision 1 , but too small on revision 2
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Before you reduce the fin size , I'd hit the rocket off the pad faster. From your picture , the rocket is already leaning to the left no more then a few feet off the rail . With all due respect , your fins are not acting as fins yet. Being over stable is more of a faster issue then a slower issue . I would use a motor like your K535 that has alot more impulse off the pad , or even step it up to a J800. Based purely off looks , your fins look just fine on revision 1 , but too small on revision 2
Good comments. It did fly straight once it left the pad, but it curved hard into the wind straight off the pad. I'd have to go back and resimulate it, but it was an 8' rail and it was a J450 on an 8 pound rocket. I don't think that makes it anything out of the ordinary, the J450 is about 80 pounds of thrust off of the pad so you're looking at 10G's acceleration? Doesn't seem anything too unreasonable. It did simulate at like 4 calibers stability like I said, so seems a bit over stable to me.

It'll be a month yet before I hit print, so I'll make sure to simulate the crap out of it. Will report back on that. The way the CAD model is set up, it's easy to cange the length of the fins.
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
353
Reaction score
147
Location
Indiana
Did you have a sim file? Cg to far ahead of the cp will make a rocket weathercok also
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Did you have a sim file? Cg to far ahead of the cp will make a rocket weathercok also
I'll dig it out when I get home. That's exactly what I thought was happening...making the fins smaller was to push the CP more forward.
 

ghuber

Member
Joined
Oct 15, 2019
Messages
7
Reaction score
2
Have you thought about simply shortening the top section of the rocket? I do a lot of 3 printed nose cones (and fins) with embedded cameras and they tend to be heavy, but making it shorter can help with being overly stable.
 

Tobor

Get your peanuts....
TRF Supporter
Joined
Oct 8, 2016
Messages
1,875
Reaction score
540
Completed the tweaks to the fincan. Made the fins quite a bit smaller and changed the angle on the bottom so they should print without support. One of the things I LOVE about 3D printing fincans is that it's easy to do a taper from root to tip, makes the fins super stiff.

View attachment 445232
View attachment 445233



I also designed a camera "pod" that will attach to the side of the fincan opposite the rail attachment point. Here's the top and bottom showing what goes where:
View attachment 445234

View attachment 445235

Idea being it can be assembled offline, attached to the airframe only if desired, and is turned on with just a single screwed Missileworks switch.


This is what it looks like put onto the fincan:
View attachment 445236



The av bay and whatnot will remain the same as the last one...only I'm changing from running 4 9V batteries to 8 1S Lipo's. Will be pretty simple to incorporate actually.
I really dig the design of your Pod. If I ever get a Prusa, I'm going to have to steal your concept.

Subscribed.
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Have you thought about simply shortening the top section of the rocket? I do a lot of 3 printed nose cones (and fins) with embedded cameras and they tend to be heavy, but making it shorter can help with being overly stable.
The nose cone on the first Basket Case was short and I hated the look of it. I think what I'm going to do is build the rest of it first, measure weight and CG, and then print the nosecone with the density/infill combination that gets me a final CG where I want it.

I really dig the design of your Pod. If I ever get a Prusa, I'm going to have to steal your concept.

Subscribed.
Thanks! Hope you have access to a file sharing service for the STL of the pod, it's like 180MB because of all the filleting done. :headspinning:
 

BDB

Absent Minded Professor
Joined
Aug 22, 2015
Messages
2,160
Reaction score
407
Following.

Did you originally print the entire AV bays for Basket Case v1, including the couplers and bulkheads, or did you just print the switchboards?

Either way...very cool project.
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Following.

Did you originally print the entire AV bays for Basket Case v1, including the couplers and bulkheads, or did you just print the switchboards?

Either way...very cool project.
Thanks!

Entire Av Bay, including bulkhead endplates, were 3D printed. It had a single piece of 1/4"-20 running thru the center that put the whole thing in compression and took the loads from the recovery harness. The Av Bay, bulkheads, etc likely won't be changed for this V2 of this rocket...was really happy with them, so don't change what isn't broken.
 
  • Like
Reactions: BDB

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Flew a smaller rocket today on an I280 with the camera I'm planning on putting into the "pod" on this build...awesome stuff, going to stay the course with that camera:

EDIT: love watching the chute release do its thing...

 
  • Like
Reactions: BDB

Red Phenix

Well-Known Member
Joined
Feb 3, 2014
Messages
73
Reaction score
14
Congrats on the successful flight! I've seen a number of over stable rockets fly in the way you described in your earlier posts.

The model you flew in the last couple of days suggests you had shortened the rocket somewhat - reduce overstability, and made the fins with a comparatively longer span.

In addition to the helpful suggestions from all posters so far (shorten rocket to decrease stability to the order of 1.5 - 2) and use fins at least one calibre in span, perhaps you might consider:

1. A split camera system - camera lens connected via a cable to a separate board, and battery. This setup will allow save you at around 30 grams - some are quite light - 18 g etc.

2. Locate all of your electronics and so on down the centre line of the rocket - which a split camera system will help you to do that - with only a few grams of camera towards the outside of of the airframe and the rest along the centreline. With a camera adding maybe 50 grams to one side of the rocket, a flier achieve the compounded effect of an overly stable rocket weather cocking, combined with off centre weight that will enhance the angle straight off the pad. As one poster suggested, a beefier motor might also assist.

Good luck
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
The one from the video was about 2 calibers, so it wasn't like it was the 3.5 or whatever the one before was.

The electronics were all in the centerline for this one, and the nosecone was overall larger diameter than the body tube so even the camera wasn't creating an offset drag.

The bigger one (that's the subject of this thread), I think I'm going to print the nosecone last, and "tune" the infill amount (and thus the mass) to try and tune the stability that way.



IMG_20210109_160826.jpg
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Someone mentioned the fins should have a span of at least the diameter. The diameter of the fincan is 88mm, so that's what I made the span.

Debating making some printer upgrades before starting...I have a mechanically stock CR-10 and it just has one rail through the middle...it has the tendency to "wobble", so I'm thinking about putting a pair of linear rails in.

Fincan with larger fins.PNG

Fincan with larger fins 2.PNG
 

Red Phenix

Well-Known Member
Joined
Feb 3, 2014
Messages
73
Reaction score
14
Is there a way you can make your rail buttons have a similar profile to the camera shroud? I ask because if you placed the 'camera shroud rail button imitators' on the opposite side of the rocket to your real shroud, you would balance the drag in one plain. Although drag is sometimes a bad thing, balanced drag might be a good one here to maximise rocket stability off the rod, and subsequently.
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Is there a way you can make your rail buttons have a similar profile to the camera shroud? I ask because if you placed the 'camera shroud rail button imitators' on the opposite side of the rocket to your real shroud, you would balance the drag in one plain. Although drag is sometimes a bad thing, balanced drag might be a good one here to maximise rocket stability off the rod, and subsequently.
Yeah, that could be done. Basically, make the button post taller and wider...no biggie. No way I could make it "balanced" but I can make it "less unbalanced" :p:headspinning:
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
7,301
Reaction score
2,257
Completed the tweaks to the fincan. Made the fins quite a bit smaller and changed the angle on the bottom so they should print without support. One of the things I LOVE about 3D printing fincans is that it's easy to do a taper from root to tip, makes the fins super stiff.

View attachment 445232
View attachment 445233



I also designed a camera "pod" that will attach to the side of the fincan opposite the rail attachment point. Here's the top and bottom showing what goes where:
View attachment 445234

View attachment 445235

Idea being it can be assembled offline, attached to the airframe only if desired, and is turned on with just a single screwed Missileworks switch.


This is what it looks like put onto the fincan:
View attachment 445236



The av bay and whatnot will remain the same as the last one...only I'm changing from running 4 9V batteries to 8 1S Lipo's. Will be pretty simple to incorporate actually.
Very cool.

Caution if you mount the camera that close to tail, blowback from blast plate may fog your lens. Not as much a problem if blast plate deflects lateral rather than straight back up.
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Caution if you mount the camera that close to tail, blowback from blast plate may fog your lens. Not as much a problem if blast plate deflects lateral rather than straight back up.
Hadn't thought of that. I have an idea around it...basically a piece of clear plastic covering the lens at something of a 45 degree angle with the tip up into the airstream - with enough air passing over, it'll rotate around and open up....something of a "tear away" like you see on dirt bike goggles or whatever. Except put it on a hinge so it doesn't end up out in the farmer's field.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
7,301
Reaction score
2,257
Should work. If you have enough rail you could also start the rocket with some sort of block or stick to keep it a bit further from the plate.
 

Dustin Lobner

Well-Known Member
TRF Supporter
Joined
Sep 3, 2019
Messages
303
Reaction score
154
Should work. If you have enough rail you could also start the rocket with some sort of block or stick to keep it a bit further from the plate.
Good thought too. All of my 3D printed rockets have had a tendency to turn hard coming off of the pad, so I'm a fan of using all of the rail I can get ahold of. Granted, a K535 will accelerate it harder than anything else I've flown on.
 
Top