How to start a rocket engine
everydayastronaut.com
everydayastronaut.com
Tim's stuff is so great. Easy to be jealous of, since being YouTuber seems easy, but to make quality content, it really can't be.
And then he's going around the moon, it's really mind blowing to see the success he's had. His interviews with Musk are a treasure trove as well, whatever you think of Musk.
My main take away from those interviews is just how knowledgable Tim is, he's able to engage in low level and in depth conversations about how these engines work. It's not just superficial high level knowledge from making videos, he is thinking himself how to optimise and improve these things, and leading that conversation. The passion for it is electric.
In another life Tim would have been an incredible engineer, but that value he brings as an educator is immeasurable. Thats how he has earnt his way to a space flight.
(They also show that the common argument that Elon doest know his stuff is wrong (at least for rockets), but I really don't what to derail this conversation into that.)
It helps a lot that Youtube seems to have become the home of long form video. Not really something that fits into traditional media. But for the people that really want to dive deep into a topic, it's great that there are now often high quality creators that cater to those tastes.
YouTube enabled everyone to publish this type of content, for good and bad...
It's depressing that good shows like that were killed off in favor of the "reality" TV and conspiracy/aliens/etc show junk food that took over Discovery and History from the mid-00s onward.
Understanding a rocket engine as a layman is easier than understanding a diesel engine. EDA acts like he's a genius but he is not.
I work in space. Some of my coworkers have met EDA. He is insufferable and extremely arrogant. A very difficult person to be around.
Yes.
> but presents himself as extremely knowledgeable.
No.
https://mobile.twitter.com/Erdayastronaut/status/14426315302...
I don't get this sense at all. I've been watching his channel for a couple of years, and I've consistently found him to portray himself as a fan/enthusiast trying his best to understand and summarize complex information he doesn't have first-hand knowledge of. He's never pretended to be an engineer.
I think the value is in getting inspired to dig deeper when he shows you something interesting.
My only defense is that Ted Lasso Season III lands next week:
YOU WORK IN SPACE?!?
Man the commute must be terrible.
Tim's content is really great though, and he does a fantastic job of explaining complex topics in a welcoming way. Very similar to smartereveryday IMO, where it is just really engaging and informative content presented in a great way.
So the 2017-2019 period where the channel took off was all done by him solo, apparently.
It’s great for views, but terrible for science education.
How electricity propagates is really complicated topic involving 3D vector calculus, for the EM waves. Most people don’t do electronic circuits by evaluating the vector field, they use the model of electron flow and the elements model (capacitance, inductance, resistance, voltage etc).
Ultimately these models are difficult to understand and most people (including my lecturers) make mistakes explaining them.
Can be in any format.
So Feynman Lectures on Physics for example are hard to beat. Though you will want to check for the various errata, the fact it was taught by a world class expert and received a great deal of peer review after the fact is about as much as you can hope for on any subject.
I suspect there’s multiple math textbooks which combined with their errata are error free, but I don’t know if that’s true.
If you’d like a 100% ‘correct’ explanation of the maxwells ‘laws’ of electrodynamics I refer to a sibling comment regarding the Feynman lectures. lectures.
A more clear approach would be to say what we mean by electricity is the net flow of energy even if no electrons move from A to B, but that’s not going to get the same number of clicks.
It can be, but as with many things it comes down to learning the techniques as well as the tools. You can learn how to edit quickly and effectively with a couple of simple rules, but the most important is "don't worry too much about throwing stuff away".
This totally depends. If you're an editor, there is a great sense of pride of turning the pile of content handed to you into something cohesive and compelling is quite a skill. Some people just don't like it, and that's fine. I don't like building UIs, but sometimes I just gotta do it. It makes me appreciate those that do the task I don't like that much more. walk a mile in another person's shoes so to speak.
Just like coding, you can get in the zone with an edit and things just start flowing. It usually comes after multiple sessions of sitting there scrubbing through the content thinking to yourself "wtf do I do with this?" when inspiration finally hits. You just start remembering a shot from this clip that flows nicely with this next clip and it suddenly "makes sense". It gets really spooky when you then try to find some audio clip like music and drop it in and it pretty much lines right up. That's for unscripted stuff that's just kind of produced like film is cheap kind of shooting.
When you have scripted stuff that every shot has been logged and tagged where there's variations on delivery or any other slight thing that makes it appear to be the same thing over and over again comes with its own challenges and rewards. Sometimes, there's a perfect delivery but something doesn't line up continuity wise, so it looks like it can't be used. Then, you scrub some other angle or reverse or cutaway and hide the edit so that you can use that perfect delivery or borrow that perfect reaction that otherwise might not have made sense.
There's a reason it's an art. Not liking it doesn't mean you're wrong for not liking it personally, but it doesn't make it the absolute worst.
Musk is a clown but I'll give him one thing: he cares about technology. That's something that very few modern CEO in big tech have and probably gives him the edge in making his project successful.
His hot takes on software / software architecture have been disappointing[1], and made me question the validity of his assertions in domains I have no expertise in (rocketry, computer vision and manufacturing).
1. Also, he wants to remain in charge of "Servers and Software" at Twitter even after (if?) He steps down as CEO.
I would be surprised if Musk gives him another interview any time soon.
His blind fanboyism and arrogance irritate so many people who work in space. I'm very surprised HN loves this guy.
It's of course unlikely that the engineering team wasn't already considering this, but it's also not like Dodd was suggesting anything, he was just asking a follow-up question. The way the conversations played out was Musk remembering to ask someone about it later to check the status of the plan or drive a decision, and later recalling that conversation when Dodd came by again.
He may be a fanboy but that fanboyism got him a trip to the moon.
SpaceX fans?
SpaceX has an effective monopoly on low cost launches for a reason. The closest company to it in terms of low cost capability is Blue Origin which hasn't even been to orbit yet. No one but ULA or Roscosmos is close in terms of reliable either. The Space Industry would still be launching single use overpriced rockets to LEO without SpaceX revolutionizing it.
If the people he interviews are humoring or correcting him, that's exactly what I would expect and is part of the value of the content really. He's giving them a platform and enthusiastic laymen a chance to ask dumb questions.
While not public, my friend was his liaison at Blue origin when he toured. He was extremely rude to the team at Blue. It actually surprised the media team how condescending he was.
In my personal experience, most people at my company don't like EDA. On the other hand they love Scott Manley. It's not about what you know it's about what kind of person you are.
With that said, if you find him irritating, then you find him irritating. Hard to argue with that.
> He is not a rocket scientist.
That might well be a pro, not a con. Rocket scientists' core competency is designing rockets, not teaching, and subject matter experts often make poor teachers. If this were a case of some kind of hucksterism, where he's an ignorant layperson making shit up and passing it off as true in his educational content, I'd say there was some concern, but while he's apparently said some dumb shit on Twitter, it doesn't seem like you or most other commenters are pointing to anything factually inaccurate _in this article_, nor indeed do people tend to on his researched, long-form stuff generally (vs. some off-the-cuff tweet). In that sense, it seems like this content is as good a place as any for laypeople to learn about this topic, that it doesn't obviously suffer from his lack of formal training, and maybe benefits if it means his better able to translate technical content to non-technical audiences.
I find it thoroughly fun to talk with subject matter experts. What I learn is amazing.
Frankly if there was a youtuber out there making high quality, good faith attempts at presenting weird networking stuff - I'd love it and probably link everyone that ever expressed mild interest to that stuff. The folks that make explainer videos well are far better than me at getting the important concepts across to neophytes, and then I can help them understand more if they are still curious. (also - if this exists and I just never came across it please link :D)
Subject: Something quantum mechanics.
Comment: "I'm not a physicist, but I think..." -- What do you think follows after such an opening? Exactly. It's fine though. I decided that the users decided that the site is at least 80% distraction and entertainment, and it still does so at a higher level than most others, so it's all good I think.
I do wish there were active equivalents for beyond software development.
Me and my colleagues joke about the weekly HN thread of people misunderstanding some physics article, or posing a nonsensical solution to a "trivial issue within physics".
He doesn't represent himself as one either. Between he and Scott Manley and others there are a lot of kids out there who are pumped about space in ways that I never felt as a kid. Is it wrong to be enthusiastic about something that is not one's own life-work, to be exited about anything headed pointy-end-up, flamey-end-down? Look at the mission statement:
Everyday Astronaut’s mission is to bring space down to Earth for everyday people. To celebrate and lift up those who are helping humanity explore the world we live on and our place amongst the stars. We believe the best way to get people excited about space exploration is through education. By breaking down complex topics, it helps give some perspective and insight into the decisions made every day through the industry. We help remove the barriers of intimidating subject matter to help foster an excited public to cheer on those who are pushing the boundaries and help inspire future generations. The point is, rocket science is awesome, and you don’t need to be a rocket scientist to be excited.
http://www.v2rocket.com/start/chapters/backfire.html
In particular, the pyrotechnic igniter that is mentioned in the article as still in use by the Russians was copied directly from there. Here's a direct link to the spot in the video where it is assembled for use.
http://large.stanford.edu/courses/2011/ph240/nguyen1/docs/SS...
Slide 94 (pdf page 100)
Technically, the SI standard does consider millimetres, centimentres, kilometres, etc. to be separate ("derived") units from the base unit of "metre". That matters when we have multiple interacting multiples, e.g. "one cubic centimetre" is not the same as "one centi cubic metre"; but of course, that's avoided if we stick to base units like cubic metre. (see http://www.chriswarbo.net/projects/units/improving_our_units... )
https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.h...
This sort of redundancy is a big problem with metric (e.g. hours, litres, tonnes, etc.); and why it's better to stick to the SI subset. http://www.chriswarbo.net/projects/units/improving_our_units...
In particular, SI is "coherent" https://en.wikipedia.org/wiki/Coherence_(units_of_measuremen...
- There is only one unit for each dimension. In your example, "grams/second" would not be a valid unit; SI only has kilograms/second (yes, it's annoying that the unit of mass has a name beginning "kilo" :( )
- The conversion factor between different dimensions is exactly 1 (by definition). In your example, the rate R is related to mass M and time T via M = TR (i.e. kilograms = seconds × kilograms/second). There are no conversion factors, since the unit of rate is derived from the units of time and mass (unlike, say, measuring energy as calories OR pound-feet OR coulomb-volts OR ounce-miles OR slug-acres-per-squared-hour OR ...)
See also http://www.chriswarbo.net/projects/units/metric_red_herring....
Overall the conversion of the unit isn't the root of the issue. Clearly defining the data types and units of everything is the key issue. This makes sure any conversion is done when necessary and allows people to design systems so that they can avoid conversion if possible.
Have you actually had that kind of unit confusion in metric, or inferring from your experience with Imperial system? It kind of just seems to reinforce suggestion that Imperial system having bunch of redundant or weird units IS the problem.
(for your defense: try [METRIC_UNIT]/h and /s. e.g. km/h often used for display in slow vehicles and m/s used for calculation motions of fast objects are kind of confusing.)
We had a pretty massive ICD that defined every message going in between sub systems down to the bit level which is what was necessary to avoid unit confusion when dealing with system creates by sub contractors and such. Your example of velocity is pretty common thing that you would have to reference the ICD for. Is this velocity signal in KM/h or m/s, as well as MPH, fps, and Mach number.
Sure you could say all velocities need to be in m/s, but then if all your control laws for higher speeds which have been fined tuned through 10s of years of work utilize Mach Number in the calculations is it safer to update all the controls laws or just do a conversion?
Mach Number is a dimensionless ratio; I don't understand what that could have to do with velocity units? (Any units used in its calculation have cancelled-out by that point)
Those are all SI units. In fact, they're all the same unit: the Watt (almost http://www.chriswarbo.net/projects/units/metric_red_herring.... )
A non-SI example would be e.g. kilowatthours (kWH); since 'hour' is not an SI unit. The SI equivalent would be 3.6 MegaJoules.
> In embedded systems you have limited bandwidth having to have large variables just to store values in SI units is a waste versus using an appropriately scaled unit and saving bandwidth.
This seems like a non-issue to me:
- Integer arithmetic can be "appropriately scaled"; we call it https://en.wikipedia.org/wiki/Fixed-point_arithmetic
- Floats are designed to be scaled, by adjusting their exponents. In the happy case, our algorithms don't care; so why not stick with standard units? In the unhappy case (imprecision, numeric instability) we may need a mixture of entirely bespoke representations, even within a single algorithm. Ideally we'd still use standard units at the "boundaries".
One of my jobs is reporting on packaging weights[1] in the UK and it's not uncommon to have this problem when I request data.
For example we request in Kgs, but one manufacturer sent back the report table of numbers in grams. That meant the thin plastic sleeve a tube of paper coffee cups comes in was reported at 30Kgs rather than 30g.
These components are all taxed / levied at various stages in the supply chain so being out by a factor of 1,000 can make a significant difference - we sanity check all our data, but a surprising number of people don't. It's not life threatening, but expensive!
[1] It's for the UK packaging waste regulations and packaging taxes. For a case of paper coffee cups we report on the weight and materials of every component such as the cardboard outer box, labels, parcel tape, inner sleeve bags, paper in the cups and the plastic lining in the cups.
It's also expected to cost billions of dollars per launch. Its more common nickname is the Senate Launch System, since it's largely just a really big pork project. It's already not especially competitive against the Falcon Heavy, and is being built at the same time SpaceX Starship is also being built. That project began in 2017, is being completely privately funded, and expected to revolutionize spaceflight once again - with costs potentially as low as $1 million per launch.
Anyhow, the SLS is reusing a bunch of old technology from the Space Shuttle. This includes the RS-25 engines...
1) NASA needs to keep in house rocketry expertise and the US government cannot rely on private companies 100% just for like NatSec reasons.
2) If NASA doesn't structure programs as pork barrel projects that make it difficult for small time senators to kill, they will constantly be nickle and dimed and have their budget slashed until their entire job is just to make memorabilia to sell.
3) Elon is not trustworthy. Our country should not rely on him. Starship hasn't launched yet, while SLS has now. I am excited for starship to launch, hopefully soon, but it's still not a functional rocket.
2) Unfortunate that our system is so corrupt, but agreed. Fortunately there is also the Artemis approach of tying in so many international partners that it becomes a matter of national prestige.
3) I suggest looking up "The Falcon 9 Heavy may some day come about. It's on the drawing board right now. SLS is real.".
Do they? Most national security work in space is under NRO and USSF, not NASA; neither of them build their own rockets but instead rely on commercial vendors.
The Army doesn't build its own rifles or tanks, the Air Force doesn't build their own fighters and bombers, and the Navy doesn't build their own ships. Operations is different from designing equipment; the only time it makes sense for the same organization to do both is when that organization is so far out on the cutting edge of innovation that they have to do both. (Ironically it's SpaceX that is in this position with regard to Starlink.)
NASA was in this position during the Apollo era. They aren't in this position anymore. It should have been a hint as early as the Shuttle era when they went and designed the Shuttle as (among other things) a satellite launch platform, only for commercial vendors to provide unmanned rockets as satellite launch platforms instead. As it stands now, NASA carries out a lot of scientific missions that don't have an immediate commercial application, which is a good thing for them to do but doesn't require them to design their own rockets.
Furthermore, it's not even fair to describe SLS as "in-house", since it's built by Boeing and Boeing is bidding the system for their own commercial contracts now. At that point it's just a question of which private company the government can rely on.
If anyone's interested the experimental high-power rocketry hobby is pretty fun, there's a lot to learn and hack on. A lot of people focus on propulsion and formulating, profiling, and flying various solid fuels they develop themselves. This guy is highly regarded https://www.nakka-rocketry.net/
Others focus on flight controllers, GPS trackers, and other electronics. https://altusmetrum.org/ (i think one of the two owners of altusmetrum is a pretty famous Debian Linux guy from back in the day)
There's also "hybrid" engines that use a solid fuel and a liquid oxidizer ( nitrous oxide ). Ex, this guy is probably the most well known in the hybrids side of the hobby https://contrailrockets.com/
Finally, there's the halfcat guys https://www.halfcatrocketry.com/ who do amateur liquid bi-prop engines in an approachable way. I've working on a design of my own based on their designs and plan to do a static fire in the Fall and hopefully a flight before end of year. The downside with liquid engines in the hobby is governing bodies Tripoli and NAR don't allow these engines at sanctioned launches. You either have to launch privately (including coordinating/paperwork with the FAA on your own ) or at FAR https://friendsofamateurrocketry.org/
I REALLY wouldn't want to be the person tasked with starting that fire.
https://github.com/AdamMarciniak/CygnusX1
It was super fun to bring together lots of different disciplines and skills. 3D printing, software, soldering, circuit design, simulation etc.
Ultimately, I got so obsessed with it I got burned out and had to take a break for a bit but came back fresh and finished it. Did a few flights over the year with more and more interesting things culminating in a dual stage flight. I've still got the rocket ready to go anytime. Just gotta wait for the weather to clear up.
IIRC the Soyuz family have five ground-start engines (propellant pump sets) which feed a total of 20 main and 12 steering combustion chambers across the center core and 4 boosters, so they need to light 32 of them for each launch.
Multiple combustion chambers per engine was their way to mitigate combustion instability; Rocketdyne blew up a lot of engines before they figured out a different approach (involving baffles on the injector plate) in the Saturn V's F1 engine.
Yes, this is mentioned in the article with a picture.
https://home.kpn.nl/panhu001/Saturn_V/Saturn_V_info/F-1_engi...
Is it true that the ignition chemical costs as much as the fuel? That sounds incredible.
All my startup and side-project ideas are now robot or machine based. Feels like the combo of LLMs (or rather large multi-modal models) and cheap robots will yield tons of interesting results over the next decade.
If it backfired. I got thrown over a Studebaker that way when I was like 8; I wasn't big enough to turn the handle by hand so I was jumping on it. It usually worked tho.
I've personally dealt with the engine in a Cirrus SR-22 just refusing to start. It was at operating temp on a hot day. We flew in to an airport with the plan being to stop just long enough to fill the fuel tanks and drain our own tanks. The engine was off for about 15 minutes when we went to restart.
We experienced vapor lock, ended up flooding the cylinders with fuel, and at that point we just had to wait. After about 10 minutes we were able to get the engine started. There are no electronics controlling this engine, everything is controlled by the pilot.
FADEC (Full-Authority Digital Engine Control) has slowly started making its way into the small piston market over the last decade, but even with that, it's still controlling engines that are fundamentally the same designs flying in the 50s.
Huge thanks to ‘Every Day Astronaut‘ for this YouTube channel, so many good videos.