All right, our next talk is from Joe Hingliff on open-source rocketry, building not only the
tools, but also the know-how, so please give a warm welcome to Joe Hingliff.
Hello.
First of all, thank you very much for having me, my mother taught me to say that in every
room I ever go into, it's a British thing, but yeah, thank you very much for having me.
So yeah, I'd like to talk to you about open-source rocketry and tools, free CAD and beyond.
And so this is an example of an open-source rocket designed that I've built and flown.
It's called the ODR rocket, it's the open-design rocket, it's up on a GitHub, it's other
repo, which is a bit random, a random place to put a rocket, but you know, and it's designed
it's just for scale, it's about a meter and a half tall, and this is designed to go
to about 1200 meters, 1200 meters in about 12 seconds.
So that's pretty violent, that's pretty fast, and yeah, it's kind of cool, it'll separate
into what two sections, apogee, put out a little drove parachute, so it comes down quick,
but close to you, and then it'll check out a bigger parachute with some electronic
dohikis that make it explode at about 200 meters, so that it slows down and comes in
and lands nicely.
But I don't just make rockets, I make all kinds of things, I actually just about managed
to earn a living, making stuff and writing about it, so I've written a free to download
book about free CAD, which is like a beautiful free and open-source mechanical CAD environment,
and I've also recently written a design, an RP2040 board with key CAD, which is the
worst title I've ever seen, I didn't choose it, it's actually just about how to get
started with key CAD and takes you through to like, you can do a PCBA board with JLC PCB.
So yeah, I make all kinds of things, you know, I've got a little educational robot that's
open-source and all kinds of stuff, and sometimes I build really tiny rockets, so this
rocket is just 18 centimeters tall, and it weighs less than 17 and a half grams, and this
is like a very proud rocket for me, because with this rocket I set a UK altitude record
for rocketry using the smallest commercially available rocket motor you can get, which
is like way less than the size of my little finger.
So yeah, and it's a good example of, there are two main problems when you start to
want to design a little rocket rather than buy a kit rocket.
The two problems that most rocketry sort of amateurs face when they start designing rockets
is one, nose cones.
So traditionally maybe rocket people would like wittle them with a knife out of a piece of
bolster wood, and it's not very good to kind of say you've read some research about
Von Carman-style nose cones with certain geometric features, you're not really going
to, well, I'm not talented enough to kind of file that out with a hand tool, so that's
one problem, and then actual rocket design, how is my vehicle stable?
Is it going to fly upwards, or is it going to do this, and then go into, usually what happens
if it does do this is when it eventually straightens out, it will go for the most expensive
car in the facility.
That's what they just do it, it's like an unwritten rule.
So yeah, so you can see, actually, the way that I took this record of a very eminent
PhD guy from a rocketry organization in ICL in the UK, is he had that to use a commercial
known nose cone bought from a model shop, by the time I tried my record attempt, I really
printing was commonplace, and so I did like a vase mode nose cone design, and then sanded
it down, and it was like if you looked at it too sternly, it would just break.
So yeah, 3D printing kind of kind of results from that, but they're the main two problems,
nose cones and stability.
So I was getting into 3D printing with my designs, and I started off using OpenSkad, which
we've heard mentioned before, with OpenFledger, fantastic piece of software that freecat
loves and interacts with, and we love it, and oh yeah, if there was a sub-title to this
talk, it's like an open source rocketry tools and a freecat and beyond, or the secret
underbelly of community developer relations.
So I was making those codes, and I found somebody had written a guy called Dave in Canada,
had written a little parametric script, which took all these complex nose cone geometries
in OpenSkad, and you could like type in the one you wanted and type in some parameters,
and it would just generate it for you, and you could render it as an STL and export it
in 3D built it.
And it was like, oh my god, this is amazing, this is fantastic.
And it was all based off like lots of this nose cone stuff, like tangent OGs and spits,
spherically, blunted, tangent OGs, and all these weird families are like, quite well documented
on Wikipedia and stuff, so Dave had gone through all this and brought this into OpenSkad
and then put his parametric file online.
And of course, it doesn't just mean that you can freely print your nose cones, you can
get into things like making moulds to make small fiberglass composite layups for your
small rocket nose cones and stuff like that.
So I kind of got that sorted and it was like, oh, this is super cool.
OK, so the other problem, the stability problem.
Well, there's a really old, well, really long running open source projects in the
lock it through a community called OpenRocket and OpenRocket is, and this is OpenRocket.
And basically, this allows you to design your rocket sort of symbolically and you can
see all the components getting added here, so there's like a nose cone and a body tube
and you can add like parachutes and you can add motors and stuff.
And you can see on the other side, I've got the nose cone dialogue open and I can select
from different families of shapes and putting different parameters.
And as it builds, as you build your rocket in this, you can see these two points,
well, you may be able to see these two points.
There's this blue point which is the center of mass and at the back end there's a red
dot which is the center of pressure.
And basically, in a very, very, in a nutshell, what you need is your center of pressure
to be behind your center of mass and you need it to be behind it, that would be very
overstable and would turn into the winter much.
You need it to be a bit behind it, but not too much is a a heuristic definitely like
there's more to it than that.
And so as you add components in OpenRocket, you can select the materials that they
made out of which obviously affects the mass and you can select the surface finish which
obviously affects things like the drag and it will adjust these coordinates for you.
And basically, you can think about it that the center of mass is where the rocket will
rotate around and the center of pressure is the length of the lever that exerts a
force on it.
So if there's a side breeze and you have a big lever with your center of pressure
far back, it will turn into the wind more which may or may not be desirable.
So what OpenRocket is doing is a complex set of equations, it's an enhanced set of the
barrowman equations which were written by a guy called Jim Barrowman in the 60s Fognassa
who realized that actually when we don't always need to put 100 like people with sliders
in a room to work out like the really complex.
Find our element stuff by hand for these things, sometimes for like our sounding rocket
program we just basically need to know if they're stable and roughly how they're going
to perform.
So that's where these equations come from.
And you can do them by hand and it's not particularly complex but there's a lot of
it and you have to do a lot of it for each component and this you make one change in
your component, you have to recalculate it all and you get to a lot of paper and a lot
of coffee but it's perfectly possible to do it without OpenRocket but it's much easier
to do it without OpenRocket.
OpenRocket has some other brilliant things so it has a database within it of all the commercially
available components for model and high power amateur rockets.
So if you have a little estes rocket that you maybe even bought in the 1970s and built
and flew as a child and you still have it, you can actually sort of create that in OpenRocket
from a known database of components and then you can simulate, say they said all you should
always fly it with this motor and you want to know how does it go with a bigger motor,
you can actually do that in this program and this database will kind of creep back in a
little bit later in the talk.
So you design your rocket and the top left bit here is you can, there's a database
of commercially available motors and you can insert those motors into your design and
it will simulate the flight so it will simulate the not just the acceleration and the altitude
but it will actually this is a two stage rocket where the two stages are coming down separately
on the two different parachutes with different drag coefficients and so it actually
shows like the two descents of the two stages and all that kind of stuff so you've got a
pretty complex kind of simulation of your flight.
The little image down on the right hand side is there's a little application outside of OpenRocket
there's another open source application that allows you to, it's really cool, it allows you to
trace and correctly scale any image of a thrust curve of a motor and so you can draw over the
top of it and put in some motor information and you can characterise and create a little rocket
simulation, a little rocket motor simulation file that you can then contribute back into the
database of motors available in OpenRocket so recently a new manufacturer has come on
line called TSP and they're making lots of rocket motors and they're publishing their
sort of data sheets with the thrust curves and I've been going through and actually making the
ENG files that we can then put back into the simulation so yeah it's super fun and but what
that means that because we can add these motor files it actually means that if you build for
example like this is half-capped rocketry in the US and and this is a completely open source
project where you can build so this is one of four rocket platforms that they've built an open source
this is Mojavez thinks apologies for pronunciation and and this is like a a bi-propellant liquid
engine rocket design that they have built and launched and then documented incredibly well
and and really really interestingly they profile their motor or a load cell or a thrust
style and publish the thing and they did all their simulations in OpenRocket so as much as I
talk about the kind of the modland of stuff and the the maybe the stuff that's like this big
don't feel that this doesn't apply to really kind of high end rocketry stuff so the one thing
that OpenRocket doesn't do it doesn't give you any CADO put so say I design something in there
and I'm like what I love this shape of thin I can't actually get like a tool path out of that
to cut that on a milling machine or a laser cutter or something so I'm involved in talking about
and helping out and I do a bit of blog writing for freecats and so I suddenly sort of became
aware of thinking well maybe there's like an idea here maybe we could have a rocket but workbench
that gets added on optionally to freecats and wouldn't it be in my my mind I was like it
be really cool if I could kind of take my design that I've done in the other tool and kind of plug
those parameters into freecats and then actually get editable sort of CAD that I can add
geometry to 3v print from and do all this stuff so but I'm not a dev I'm not a dev at all so
I have no idea how to build that so my approach was I put up a request for comments on the
freecats thought for them and paid my dues you know first of all massive thanks for the freecats
community from such an amazing project blah blah then I explain my kind of where I'm at I'm really
into this and I kind of think rocket is interesting and then do you remember Dave from Canada
I found him on Twitter and I'm not that he saw this thing so so quite early on in the response
he was like oh hey everybody I yeah I did some stuff in open schedule I developed a macro
for nosecoar and some for freecats and yeah oh if people are having problems with that maybe
yeah I'm not sure as there's enough for a rocket workbench I'm not sure and then at one point
if you see the sort of third line from the bottom you put convince me so I did three messages
later curse you concrete dark which is my online Nick for sucking me in thank you to this a
little more in the context of open rocket it's going to be quite tricky blah blah I don't know
how I do this I'm not sure how I do this cue the community ah what you would do is you would do
this and of course this is the beautiful wonderful secret well not secret here the wonderful secret
source of the open source community isn't it that we all help each other so there's this guy who's
kind of like nearly at the point where we can build a a a workbench and the community sees that
there's an opportunity here and they backfill all this in so Dave I I I giggle with him that I've like
ruined his retirement he's a software he's like he'd literally just is the resigned and I made
more work for him than the last 10 years of his career but we we giggle about it but he's really
enjoying his his time in freak out and in the community and so yeah and so cut to a few months later
this is like one of the first early versions of the freak out rocket workbench so you plug it
in via the other manager and it has you can see the yellow symbols there and they all track
to like rocket components that you can add in to your design so I've just grabbed this from the
documentation so there's like create a nose cone create transition sections great body to
central these all these parts create thin cans and fins and so yeah so it's really really cool
but what's even cooler is he really kind of got my original idea of let's make it work in an
operable way similar to open rocket so do you remember I said about the database in open rocket
there's the same database because it's open it's open data so you can go into the rocket
workbench in freak out and you can either parametrically insert a nose cone and even this looks
the same as open rocket you can click through the same family of nose cones you can put in the
same parameters but instead of just a simulation 2D item it will produce like geometry in the preview
or you can go into the database of known components and you can pull in a component that
exists so your grandparent's 1960s ss model rocket that's missing a nose cone that's in the loft
you can 3D print a brand new one that will print perfectly and one of the beautiful things
about this is that I can go into a rocket's a community who've never used freak out and I can
get to the point where they have an STL of something they absolutely love you know a bit like
model where were guys the things in rocket that I can show like a man of a certain age in
rocketry and a certain nose cone and they like oh god that makes me feel alive and so yeah I
can get to that point where they have that STL ready to print in about 20 clicks without even
installing like from downloading freak out so it's super cool as a sort of outreach thing
then this isn't particularly my bag but rocketry people are mad into they build a design and
then they want to make it massive or they want to make it smaller or they have at something from
the 60s and they want to make it bigger because they've got basically rocketry is a really good
way to fold up all the money you earn and set fire to it in a field and they really want to do
it and they want to do it in things that look like big versions of things they had as kids so again
about 25 clicks you can get in those cone in you can jump out of the rocket workbench
and use all the other tools in freak out so here we are in the draft workbench I've selected
the nose cone I've put you know scale it by you know XYZ factor of 2 and there we go this one
that's twice the size so scale modeling which is not my bag but is a real bag in the community
is is really kind of tangible and doable and then of course that's the gateway drug for these
poor rocketry people wondering around not using CAD who end up here they then say oh well
it'd be really nice if I could put something like attach my my landed that keeps the nose cone
attached to the rocket when it all comes down under a parachute blah blah blah and so of course then
you start to find these people are now exploring like the regular kind of like part design the
very core sort of CAD parts of freak out and basically learning general CAD to add kind of stuff
to their components but there's some really complex stuff in this in this that doesn't exist
in any of the CAD anywhere else in the world so like for example some people like to build rockets
where the thin and the can of the fins that it attaches to is all the same device so there's a
kind of section where you can you can create these parametrically but what's really interesting is
what Dave's got into around this so he has some test branches and some of the stuff that's
happening in test branches he's actually now stuff that's really interesting for people in the
rocketry industry like people at ESA and stuff like that so he has a tool that basically can perform
thin flutter analysis so even an even a reasonably small high power rocket as that rocket
approaches or transitions to Mac your fins are going to flutter and it's a real engineering headache
to work out how robust and my fins need to be to survive this flight and thin flutter analysis is
like there's a heap of academic papers out there it's a very complex set of maths but it's a process
that's really we're doing because of course if you reinforce them too much they're heavy and they're
more draggy so you want the minimum amount of sort of stuff you can do to make your rocket survive so
and this tool is now coming into the test branches that performs these these things in a really
kind of friendly way and so that's yeah so the test branches are really interesting to check out
he's also linking it all up to the sort of computational fluid dynamic stuff that's built into
free card with you know all the open forms of poor and all the the different solvers and stuff
and so and what's really interesting for me is that I'm starting to see in sort of other sectors
of rocketry like this is a long standing American newsletter about rocketry that comes out
once a month there was two articles that featured free card and the CFD kind of workbench the
rocket workbench and there was somebody from very much from the rocketry community not from the
CAD community teaching other people through tutorial how to do sort of fluid dynamics on model
rocket designs and I just kind of think hey that's super cool to see that's super cool so and so Dave
you know I've kind of ruined his life he one of the big things he's working on
American free card is he's actually started to work on core parts of free card because it impacts
on the model rocket stuff so he is now working massively on the material editor for free card
because what we want to be able to do is know how much the nose cones weigh and other other
other all this kind of stuff so he's actually now become this like really central kind of core
contributor and free card and how did I thank Dave how did I thank him last year I built this open
source rocket and because I am an awkward sod who decided to build it completely hexagonal
because I thought that would be cool I couldn't use any of Dave's tools I mean I'm a terrible human
being and basically so that the whole talk which is coming to an end now is to be where be where
of sneaky community developers like me trying to ensnare you into these one little things but
the serious point that I'll finish on is none of these tools could exist in proprietary software
you could not go to or to there for anybody and say hey can you build it what you could but they've
won $20 million so yeah and the fact that these two communities open rocket and the rocket
workmen add on with in free card are all really happily kind of working together there's kind
of pushing and pulling and that they complement each other they share databases the database in open
rocket is way better because it's been pushed by the people coming through the free card route
it's all just gorgeous right I shall stop thank you very much for having me
question
so I should probably mute it well I slurped water sorry hey thanks for the talk
actually two questions but one is is the interaction with the other workbenches like
airfoil for example and the second question is in open rocket you showed all the
these stability analysis is that also included in the rocket workbench and so is there any
point to still having open rocket so there were there were two questions one is about
is the stuff about stability in the rocket workbench included and the other one was about
is it therefore and then is there any kind of point to the open rocket part anymore so
and I don't think so down the line Dave plans to make it so that we can actually natively open
the ORK files which are what open rocket uses and so that it creates our kind of card stuff
I don't think it particularly has plans to take over the core feature of open rocket which is
the simulation that's pretty robust and there are there are lots of people in the rocket
community who that tool is enough for that and that's all they want to use so I think just as a
sort of cursing we're probably not going to build that stuff into into the rocket workbench because
it works super pretty well yeah so exporting and analysis and so it's coming in the testing and
the air flow workbench is interesting I'm not that familiar with it I'm not sure it's is it has
that actively developed at the moment I'm not sure and but certainly the CDF the you know the
I never thank you and the CFD workbench that that helpfully helps you install open form
open foam yeah it links to all of that so yeah cool
yeah two questions one could you reuse any code from open rocket and two is this going to
lead to freak out having export restrictions for being able to do so yeah so the first question
was can you reuse any of the code in open rocket in the rocket workbench and the second one was
can any of this can it could it lead to freak out restrictions due to it or similar
first question I don't really know I'm not a dev I'm a word that open rocket is actually a
Java application so so that you know but certainly there's a lot of shared resources there with
not shared code and as an aside the development of this rocket workbench is actually reinvigorated
the open sorry the rocket workbench in freak out has actually really reinvigorated the team and
new contributors to the open rocket project so that's had a great load of incremental leaps
the second one about ITAR I doubt it yeah I doubt that and the rocket workbench is ever going to
be a core part of freak out it's always going to be an adult and I think that gives us some nice
ways of saying it yes you could do whatever you like in your country but it does not come with this tool
okay thank you Jill you're welcome
thank you
right here
All right, can you test your microphone?
All right, test test?
Yes.
Okay, welcome to the open hardware.
We're dead for this Sunday afternoon.
Our next presentation is one that we have had more questions on than just about any other presentation.
How do I draw beautiful wire diagrams?
Is there something out there?
Yes, there is.
We are going to now hear about wire viz and making your wiring cabinets more beautiful.
So please,