Well that sucked...

Can't believe it's been over a year since I posted anything...nevermind, I can, cause most of 2022 and 2023 sucked. Amid a plethora of life crises, I found out in September that my comps were expiring in December, which meant it was do or die for my PhD. That and all the other terrible things that happened made these the worst few years of my life. But this isn't a life blog; I'll spare you the depressing details, so fun things only:

 

PhD

First, and finally, after over 7 years as a PhD student and over 10 as a grad student, I'm a Dr. Since I work with launch vehicles, do related research, and am a thermal-fluid subject matter expert, I guess I'm now officially a rocket scientist? I'm so glad it's over, feels surreal, or maybe that's just shellshock+severe burnout+trippy-exhaustion. I'm not sure I'd ever recommend getting a PhD for an aerospace engineer, except maybe if you want to do controls or teach, but I definitely don't recommend trying to get one while working full time. Once you start making real money, motivation and time plummets...there's nothing quite like being on grad-slave wages to motivate finishing. I've heard working while studying is not too bad with a flexible/supportive work place, an excellent advisor/department, and a straightforward project. NASA is a fantastic place to work and, compared to most companies, very understanding of life problems and supportive of higher education. My research had data quality issues (from one experiment I didn't design or run) and was anything but straightforward. That + life :( + real job $= zapped motivation to work on it = 7 year PhD. Don't do what I did, just don't. I'm glad it's over.

The projects that were part of the PhD were pretty cool, though, both related to microgravity propellant slosh dynamics. I got to ride in a Zero-G plane, which was the coolest thing I've ever done and funnest experience I've ever had.

Floating upside down

About 1/3 of the plane puked, but I don't get motion sickness, so it was a blast for me. If you ever get the chance to go on a zero-g plane, do it. I'm still writing a bunch of papers from this research and stuff that spun off it.

Mill

I got a mini mill off marketplace for a steal.

Mini mill is mini

Now I have a mini-mill and mini lathe (relocated), though haven't done (had the time and energy to do) much with either yet. It's sitting on the antique workbench I refurbished....oh! I learned from a car guy why the oil-based paint took forever to harden: FL humidity. You really need to use a dehumidified paint booth in FL. I'll probably make one out of a pop up tent and AC/dehumidifier next time I need to paint something.

 

Really, it's not a life blog...well, maybe a little

I'm jealous of people who have big home machine shops. That's been my dream since MIT, actually probably since high school, although I can't remember much of anything from back then. I know the me-from-then would be depressed to hear I'm still not quite there yet. I can now see the light at the end of the tunnel, but getting there is, and will continue to be, so much slower than I'd like. Part of the reason is this house...the garage has a low ceiling and is at the bottom of a steep driveway, there's just no good way to get a large mill or lathe in it. Also doesn't have land to build a shop. So I'm planning to move...eventually. House has a bunch of issues that have to be fixed before I can sell it, but it's not like I can afford a house with the current interest rates even after selling this one, so heck knows when that'll happen.

Also, I mentioned NASA is a great place to work, but the salaries are badly lagging industry ...That was always to true to an extent, but inflation and talent demand from all of the rocket companies has made it so much worse the past few years. I applied to blue origin and got an offer way (wayyy) over what I make now, but it came down to a quality of life (more hours, no work from home, less PTO, etc) vs. money thing. I ultimately stayed at NASA. I mentioned my life was sucking...not going to try to convey that here, but most of that wasn't money driven, so I think choosing QoL over money was the right choice, despite a lack of funds being one of the reasons I don't have a nice shop.

I know I said this wasn't a life blog, but I want to say this: life is messy. There are so many posts, articles, blogs, vlogs, etc showing people having everything you might want and living perfect lives...all of it is garbage. They only show you what they want you to see. Unless you're rich, real life isn't like that, so don't feel bad when you see that crap. AI is just making that worse because now pretty much everything on the internet can be faked: pictures, videos, and even whole blogs. There is so much click-bait like "I built this [insert amazing thing] in 1 day!"...bullshit. Them lying like that to generate ad revenue bugs the shit out of me if I let it. I try to be open/honest about how much time and effort the projects I document in this blog take, and I mention everything that inevitably goes wrong. I also don't, and will never, monetize this blog. Ignore all the BS, do your own thing, go at your own pace, and try to have fun when life isn't sucking. I know I'll probably be 40 before I get the shop I want, about 20 years later than I wanted, but I'll get there.

Small Parts Organization

While I didn't have time to do much else related to the shop, I did have time to finally organize all of my screws and small parts. You can actually see some of the organizers I started to accumulate back in late 2021 in a picture in this post, but I didn't start organizing in earnest until this year. The organizers are the Hypertough ones from Walmart, which are the same as the HDX ones from Home Depot except the HDX ones have orange latches and inserts instead of red. They come in 2 packs, used to be $10, then it was $12. Ended up needing over 30 of them. I designed bin inserts for the organizers, which actually cost more in filament than just buying more organizers, though they do save space and are convenient. I designed stackable cabinets to hold them.

Small parts organizer cabinet

There are a bunch of neat cabinet designs out there for these and other brand organizers. The organizers I'm using had the lowest $/volume ratio I could find, and I think this cabinet will take less time to build than one based on dados. The panels are 3/4 plywood, glued and pocket-hole-screwed. The rails are 1.5x1.5x1/16" aluminum angle, which I can source locally from a place in orlando for cheap, and they may even cut them for me, though I could cut them with my miter saw or chop saw if I really had to. No need for wheels, part of the point of the organizers is that I can pull out the one I need and take it to wherever I'm working. I haven't built the cabinets yet because time and money, and a (functional) tablesaw would be nicer than a circular saw for cutting the panels. The organizers are just stacked at the moment. I also organized medium-sized parts, like arduinos, in storage bins:

Organized

Oh, and as shown above, I moved the printers out of the garage into a spare bedroom-turned-hobby-room.

Rocket Garden

I 3D printed a rocket garden for my desk at work. 

 

Rockets!

All documents are digital now, so I decided to fill up the drab cubical real estate with these. Kind of an old pic, there are more now, and along with a 1/30th scale Apollo lander with astronauts and a rover off to the right. I'm working on a mercury-redstone and the JWST now. I found all of these files for free on the internet, though I occasionally fix things I don't like about them.

Wanhao i3

My ancient shitty, yet super upgraded, wanhao i3 just passed the 25km of filament printed mark! It works juuusssssttttttt well enough to kill my motivation to finish CubeXY. That's also why I haven't bought a new printer, cause that'll just kill my motivation more. Instead, I spend more money on the i3 because that makes sense (/s). I replaced the glass bed+PEI sheet with a magnetic build plate, which is night-and-day easier to use and was worth every penny.

New build plate

 

You can see the knob from a new Y-axis belt tensioner in the above pic, too. The old printed support structure crumbled, so I switch it to back-braced. The braces are now out of the way, though they are not quite as stiff.

 

New braces

I printed a bunch of random things over the past year, like this mechanical dragonfly:

For the wings, I printed one layer of clear PETG on a textured build plate, then used atomic filament bronze PETG for the rest. I think they came out decently realistic. I think the oof stones might be my favorite:

Printed with Atomic Filament Marble PETG

Future plans:

Table saw: Come December, it'll be the 2 year anniversary of having a disassembled 113 table saw in my garage. I bought a second one recently for spare parts and it has a much nicer fence than the original. I should be able to make one nice saw from all that, and sell the left overs. I will finish it. All the pics and the blog entries on this have turned out to be super helpful since I don't remember what goes where.

Workbench: 3-year anniversary, and I don't have all of the tools that were going to go in this anymore, so it needs some re-design... 😅 I'll definitely finish this. Need a working table saw first. 

CubeXY 3D printer: over 4 years (RIP). I still have all of the parts, just never got around to assembling it. But I will finish it, and it might will be awesome. 

H1 rocket engine turbine display case: Now that I finally have a mill, I can cut the parts for a stand for this. Need to de-rust it first.

Homelab: I have access to compute clusters at work, so I don't have plans to build a new homelab cluster. I have (very) slowly been accumulating parts to build a dual AMD EPYC machine, which, if my calculations were correct all those years ago, it should be nearly as fast as my entire cluster was. I still have the old head node, not exactly sure what I'm going to do with it yet, maybe turn it in to a NAS since it has a bunch of drive bays. I want to set up some self-hosted services. 

That's all for now.

Been busy...

Back stateside again. Still very limited on room, though, so hobby progress has been limited.

Got the 3D printer recalibrated and set up on a shelf in the garage.

Wanhao i3 V2.1

Moved the filament spool off the top to the side. Bought a 16x16" tile for it to sit on, perfect size. Smoke alarm taped to the underside of the next shelf up (top left of picture). The filament dryer is the same one I had in England, so I have a 110V-220V power adapter sitting behind it. I found the same one in the US but for 110V power on eBay for $39 ("Rosewill" brand here), and I bought it so I can ditch the giant power adapter. The clear plastic cylinder parts should be the same, so I can extend it to hold 3-4 spools, which is nice. Printed an XYZ calibration cube and benchy first, then a new spool holder since the green one was on its last legs. Currently printing some wall mount holders for remotes for new ceiling fans we bought my mother in law for Christmas (guess who gets to install them...). 3D printer to-do: replace X belt and add belt tensioner.

I've been mentoring FloridaTech's Base11 space challenge team (Florida Tech Rocketry, FTR). The goal is to be the first university team to launch a liquid bipropellant rocket to space. I've been teaching them fluid systems analysis, fluid systems component selection, CFD, structural analysis, thermal analysis, basic design process, etc etc etc. They have a pretty solid preliminary rocket design and detailed engine and test stand design now. FIT promised to fund the whole thing, but you know how that goes...so currently looking at other funding options.

I've also been spending a lot of time over the past couple years working research contracts for various aerospace companies, most of them slosh CFD or slosh testing related. FIT has a large linear stage capable of shaking full scale spacecraft tanks, and we've designed and are fabricating a second one now. We got about half way through a NASA spacecraft tank test program before realizing we'd need a linear stage capable of much higher frequency excitation than the current one , or anyone has as far as I know...I mean, I guess there are vibration tables, but the excitation amplitude on those is tiny. The new linear stage should be capable of shaking 8000lb tanks at 6 Hz over ~4mm, which is kinda terrifying. Currently finishing fabrication on 1/5 scale upper stage propellant tank simulators. Slosh testing will start in about a month on those. My advisor and I wrote (so basically I wrote...) a proposal for another NASA slosh research project that got approved, so that's probably coming March-ish. I'm leading about 3 grad students and 4 undergrads working on these and some other aerospace/propulsion related projects.

Busy busy. So even though most of this blog is about my hobbies and not-rocket stuff, I am doing a lot of "rocket science", though I should have foreseen I wouldn't be at "MIT" for ever. Kinda dumb naming the blog that, oh well...live and learn.

As I tell the FTR team: "Skip all your classes, build rockets".

Making more things

I made some things recently.

My partner likes pink, so I painted the desktop "candy pink". They've been running astrophysics-y python codes, and their laptop just isn't cutting it anymore.

I also printed out the sugar glider decal.
Paint and decals make things faster, yes?

I modeled and 3D printed a Delta II rocket fairing for a downloadable 3D model of the Kepler Space Telescope, which I also 3D printed.

I put it on Thingiverse (see here for more info).

L3 Rocket

Purpose: document the build and flight of my Tripoli Level 3 certification rocket

I've always liked the Phoenix AIM-54A missile. I had an Estes kit of it when I was little that I put a 24mm motor mount in it. I flew it probably close to 50 times before it died. I've seen a few larger scale Phoenix missiles, but I've never seen a 1/2 scale kit, so I decided to custom build one.

I got the specs from here. Using stock 7.5" ID, 7.75" OD phenolic tubing results in a 0.517 scale, which is close enough. Given that, the body tube length should be about 63", and the nose cone should be slightly less than 3 to 1. Though it's not ogive in real life, 3:1 7.5" ogive nosecones are commercially available, so I decided to use one and make the body tube slightly less than 63" to compensate for the slightly too long nose cone. I decided on a 3ft long, 98mm motor mount and 1/4" thick 12ply wood fins. I'm building it super tough, so it should be able to go supersonic (large M or small N motors).

The rocket was designed in OpenRocket and Solidworks.

Solidworks model of stretch 1/2 scale Phoenix

OpenRocket model of Phoenix

OpenRocket model of Stretched Phoenix

OpenRocket is predicting ~7000ft for the stretched (dual deploy) Phoenix on a medium M. It predicts ~2000ft on a medium K for the non-stretched Phoenix. Both configurations will use about 4lbs of nose weight. This is due to the stubby and spread-out nature of the fin area, causing the CP to be further forward than usual for a rocket this size.

My dad gave me two 48" long, 7.5" phenolic tubes, two 12" couplers, and 48" of 98mm phenolic motor mount tube. He also has (had) tons of fiberglass, so he let me use it. This wasn't my first time making composite rocket tubes, but I didn't have all the supplies I was used to (MIT Rocket Team, DBF had vacuum bagging supplies we used to make tubes with...I was spoiled) at dad's house, so I had to do a basic wet wrap. I measured and cut two wraps of ~10oz 0-90 E-glass and two wraps of ~4oz 0-90 S-glass for each tube. I used medium cure time West Systems epoxy and wet out the FG as I was laying/stretching it around the tubes.

Setup for layup. Katie's L3 kit is in the background

Lots of fiberglass

Finished layup

Heated cure

Each tube went from 3lb pre-glass to ~5lb 12oz post-glass. Final OD was ~7.75". The surface finish was terrible (no peel ply or release, no vac bag, etc. ), so I had to do a ton of sanding and filling (two coats of automotive spray primer and filler). You can see the result in some of the pics below. Total time spent on the tubes was probably 20-30 hours. 

If I had left the couplers stock, I ran the risk of coupler failure (breaking in half), which is common in these large rockets during high accelerations. So I fiberglassed the insides with 2-3 layers of 10oz glass. Balloons were used to hold the glass against the insides, then popped after curing.

 

I wanted to do 1/8" G10 fins, but I do not have access to a CNC router or large enough laser cutter here. Custom fins would have been ~$400, which is crazy, so I bought a $50 sheet of 12ply plywood from aircraftspruce. I penciled the lines using a cardboard stencil and checked them all with a ruler. 

I then cut them out with an oscillating saw. I tried to sand them with a palm sander and sanding block, but quickly realized it really needs to be done with a belt sander, particularly the beveling. I'll finish them later. I'm going to build a jig for the FIT shops's belt sander and do the beveling there.

I slotted the tube next using a Dremel and reinforced cut-off wheel. I made two slits lengthwise per slot, then broke the material in the slot out using needle nose pliers. Fiberglass is brittle, and the thin/small amount on the ends of each slot made breaking it out easy. I then finished the ends of the slots with a 1/4" sanding drum attachment.

All tubes done

All tube ends were sanded smooth, treated with thin CA, then sanded smooth again to prevent phenolic wear.

Left to do:

• Buy plywood centering rings, bulk head, nose cone, altimeters
• Cut motor mount tube
• Finish sanding fins
• Make motor mount
• Install fins
• Filleting 
• Build altimeter bay
• Minor stuff
• Final primer coat, sanding, then painting

The fins will have internal and external fillets. The rear two centering rings will not be installed until the set of fins they contact are completely done so that the volume they enclose can be filled with expanding foam. The shock-cord mount will be a pair of U-bolts in the forward centering ring. Altimeter bay will be classic rods + sled construction. I haven't picked the altimeters yet. The goal is to be finished by December.

Next time I build a big rocket, I will probably order pre-glassed tubes unless I can figure out a way to get a much nicer surface finish. I'll get them pre-slotted, too, unless I build a nice router tube slotting machine/jig. I want a CNC router and laser cutter in my home shop eventually, so that will make fins significantly easier. 

Rockets

Finally, a post inline with the name of this blog! I've been working on a rocket for Southern Thunder 2010 for the past week or so. I plan on certifying Level 1 and 2 with it.

Note: This build log is written for people with some previous knowledge of high-power model rocketry.

This rocket is a Blackhawk R&D 3" Stinger kit. It came as a kit with pre-cut fins and tubes, which is very convenient. I cut my own fins/tubes for many of my rockets, and it can be a real pain.
The first steps were to rough up the 3" body tubes and glass them (I'm going to put a J engine in it afterall).

Fiberglassing setup. The tubes are slid on here and laid up. Note the wax paper on the floor.

Glassed tubes. 

Leftover resin formed to the shape of a cup it was in.

I used 4 oz. glass and West Systems 105/205 resin. You can see the rings I trimmed off the ends of the tubes in one of the above pics. The discoloration is where the resin soaked into the tubes differently. I then had to cut out the fin slits.

 

Then I soaked the ends of the tubes in superglue and sanded them to keep them from burring.

The dark ring is superglue.

The next step was to make the motor mount (the thing that holds the rocket engine). 

  Here's the forward centering ring epoxied on to the motor tube. 

Kevlar is used for the first part of the shock cord because it's fire-resistant (there's a black-powder ejection charge that fires to deploy the drogue or main chute depending on setup) and won't wear out as fast as a regular shock cord. This will be attached to a shock cord, which will be attached to the bulkhead.

While that was drying, I started working on the payload section:

Here's the bulk head epoxied in. I used some Kevlar pulp in the epoxy to strengthen it. Another common filler is short carbon fiber threads; I couldn't find our bag of them, so I just went with the Kevlar. Silica/micro-balloons are other common fillers.

Filleting the other side of the bulk head with epoxy.

Then the motor mount was shoved into the aft end of the body tube and glued with some 5-minute and filleted:

The shiny stuff inside the tube is a fillet of about 30 grams of West Systems mixed with Kevlar pulp poured in. That centering ring is a good 18 inches down the front end of the body tube, so the only way I could get the epoxy in there is to aim, pour, and hope I didn't make too big of a mess.
While that was setting, I worked on the back centering ring. I didn't glue the two aft centering rings in (so only the one forward ring got glued in) when I glued the motor mount; you'll see why in a moment. The back centering ring needs motor retention screw mounts:

Motor retention screw mounts epoxied in.

While all that was drying, I worked on the fins. They are laser cut out of 3/16" plywood- very nice by my standards. The edges needed to be tapered/sanded, so I went to the belt sander:

A rounded rear fin.

I also drilled 1/16" holes in the fins near the body tube interface.

 

Forward fins. The fin tabs were cut a little short, so I glued a then strip of balsa to the bottoms.

These holes will act like rivets when filled with epoxy when filleting. The next step was to glue in the forward fins.

First fin glued in.

All forward fins glued in. Note the aft centering ring: it's not glued in, just holding the motor tube centered.

After gluing the fins in, they needed to be filleted. I used West Systems/Kevlar pulp again. Some people do tip to tip fin glassing at this point. I didn't feel that it was necessary with this rocket. My view is that it is only necessary for rockets flying L motors and over, or anything going Mach.

I normally fillet the inside of the fins while doing the outside fillets, but I couldn't on the forward fins because of their displacement from the rear end of the rocket (you'll see in a moment how I did it on the aft fins). So I needed some other type of inside strengthener. Expanding foam to the rescue! 

The setup. Rocket, expanding foam, and MEK for clean up (lost the acetone).

I enlisted dad's hands for this part because foam is messy stuff. We attached some straw extensions to the foam nozzle in order to reach all the way down to the forward centering ring. Then I sprayed a bunch of the stuff in there. The stuff expanded a bit more than we thought, so I grabbed the middle centering ring and shoved it in there to stop the expansion. You can still see some of the mess after the first few rounds of clean up in the following pics:

The straw extension.

Overall, this method worked very well. The next step was gluing in the back fins and filleting them, outside and inside.

Note the inner fillets on the motor tube and body tube.

Instead of inner fillets, many people put sections of fiberglass on the inside. Again, I didn't think it was necessary on this rocket. 

Then the aft centering ring was epoxied in and filleted. 

 And that's it for the structure! Next, primering and painting. 

I sprayed two coats of heavy filler primer, then wet sanded. 

Much smoother!

 However, this primer is also really good at filling in the spots between grains in sandpaper. So I went through a lot of sandpaper:

 

Overall, I did three primer coats. Next came painting. I forgot to paint the tube white before laying down a coat of yellow on the gray primer, so I ended up having to do three coats of yellow...oh well.

Painting the fins black.

Painting black stripes.

Finished paint job! Not my best work, but ok. Time for decal work.

Post-clear coat. Done!

I now have a rocket that is basically ready for an H and J motor at Southern Thunder. It's missing an altimeter bay for dual deployment (necessary for the 7000ish feet high that it will go on the J), but that's a short/easy project.
It's also long enough for a smallish, e.g. I, hybrid engine, so that might happen if I get my cert flights in in time.

The pile of hybrid engine parts.

I'll post a few pics of the launch next week.