[HN Gopher] How to start a rocket engine
___________________________________________________________________
How to start a rocket engine
Author : Jarlakxen
Score : 302 points
Date : 2023-03-10 09:57 UTC (13 hours ago)
(HTM) web link (everydayastronaut.com)
(TXT) w3m dump (everydayastronaut.com)
| fnordpiglet wrote:
| This is great. My rocket starting experiences extend to hitting
| space in KSP and mashing the red button on an Estes launcher. To
| be fair in KSP they often wiggle to death on the pad and I've
| spent more time with bored 6 year olds wandering off as I figure
| out why the Estes motor didn't ignite, but that's nothing
| compared to this.
| rwmj wrote:
| _> [Ignition chemical TEA-TEB] is quite expensive, costing
| roughly the same as the cost of RP-1 for the Falcon 9._
|
| Is it true that the ignition chemical costs as much as the fuel?
| That sounds incredible.
| hoorayimhelping wrote:
| Tangential but related: "Toxic Propellant Hazards"[1] a video
| made in the mid/late 60s and published by the US National
| Archives Youtube channel. In addition to having some great
| information about hypergolic propellants, and having some
| interesting footage showing what they're like to use, it also has
| that mid-century production quality, the kind that the Fallout
| games love to simultaneously lampoon and pay homage to
|
| 1) https://www.youtube.com/watch?v=Zha9DyS-PPA
| mackevers wrote:
| [flagged]
| dale_glass wrote:
| Is that ChatGPT?
|
| Edit: Yup, I got something very close to that:
| https://imgur.com/PX0MmCR
| chasd00 wrote:
| I think there was a russian engine that literally had 2x4's on
| fire stuck in the combustion chamber in place of torch ignitors
| or TEAB.
|
| 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/
| bewaretheirs wrote:
| Yes, the Soyuz (the workhorse Soviet/Russian launcher for crew,
| smaller satellites, and space station cargo) is ignited that
| way (and it's mentioned at the Everyday Astronaut page linked
| above, just under the "Ignition on the Ground" heading). There
| are pyros on top of the wood, so it's really just a really
| large electrically ignited match.
|
| 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.
| WalterBright wrote:
| The V2 used baffles, too.
| pasiaj wrote:
| > literally had 2x4's on fire stuck in the combustion chamber
|
| I REALLY wouldn't want to be the person tasked with starting
| that fire.
| jaywalk wrote:
| > I think there was a russian engine that literally had 2x4's
| on fire stuck in the combustion chamber in place of torch
| ignitors or TEAB.
|
| Yes, this is mentioned in the article with a picture.
| skazazes wrote:
| You probably already know of him, but you should check out BPS
| Space on youtube if you enjoy long-form video edutainment. Much
| like Tim Dodd, Joe makes videos full of detail and information
| about topics he is clearly passionate about. In the case of BPS
| Space that is pushing the limits of amateur rocketry in a
| uniquely hacker/programmer friendly manor.
| polishdude20 wrote:
| BPS Space is what got me into building my own thrust
| vectoring rocket during COVID lockdowns.
|
| 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.
| mannykannot wrote:
| There's lots of information here on the sequence of operations
| followed in starting the F1 motors of the Saturn V first stage:
|
| https://home.kpn.nl/panhu001/Saturn_V/Saturn_V_info/F-1_engi...
| mtlebe wrote:
| Related video: How To Start The Massive F-1 Rocket Engine from
| Scott Manley: https://www.youtube.com/watch?v=2cldgl9IIyY
| HPsquared wrote:
| Space shuttle main engines (RS-25) had a very complicated startup
| process, deviations from this could cause all sorts of different
| things to fail catastrophically.
|
| http://large.stanford.edu/courses/2011/ph240/nguyen1/docs/SS...
|
| Slide 94 (pdf page 100)
| EvanAnderson wrote:
| All the imperial units in this PDF hurt my head. I'm an
| American, so I'm used to them, but seeing them in the context
| of precision aerospace hardware is so jarring. As a student it
| seemed like math re: chemistry and physics was so much easier
| (read: less error-prone) with metric units than with imperial.
| Mars Climate Orbiter indeed.
| Koshkin wrote:
| I mean, sure, converting grams to kilograms is easier (for a
| human) than converting ounces to pounds, but how often do we
| have to do that in our heads? Computers, on the other hand,
| do not care (and they "prefer" the binary system anyway).
| perilunar wrote:
| Converting grams to kilograms not so much, but mm to m, mL
| to L, even g to mL and L to kg (of water) -- all the time,
| and of course in our heads -- it's so easy you barely need
| to think about it.
| chriswarbo wrote:
| I don't even consider those to be "conversions" at all;
| in the same way that "two dozen metres" and "twenty four
| metres" and are both just some number of metres (not a
| conversion from a separate "dozen-metre" unit).
|
| 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... )
| sbradford26 wrote:
| The biggest lessons learned on the Mars Climate Orbiter
| wasn't exactly that everything should be metric. It was the
| unit conversion is dangerous and needs to be handled very
| carefully. Just saying everything will be metric doesn't
| avoid unit conversion. You might have one thing measuring
| fuel burn rate in grams/second and another in kg/second. That
| conversion can still lead to issues if not handled correctly.
| In the context of the space shuttle it was all designed in
| imperial units starting in the 70s so it would be very risky
| to convert everything to metric.
| chriswarbo wrote:
| > You might have one thing measuring fuel burn rate in
| grams/second and another in kg/second
|
| 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/wi
| ki/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 x 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_re
| d_herring....
| sbradford26 wrote:
| When designing new systems it is best to clearly define
| the expected units for everything clearly at the start.
| SI units are great but sometimes they are not great for
| the specific use case. When measuring high power systems
| like power plants or EVs kW/MW/GW are a more appropriate
| unit versus Watts. 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.
|
| 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.
| numpad0 wrote:
| INT_MAX is usually 2147483648, which means a "power"
| figure in Watt can handle anything from a laptop CPU to a
| Chernobyl power plant. FLT_MAX and _MIN are e+38 and e-38
| so couple digits over and under(within 32bit precision).
|
| 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.)
| sbradford26 wrote:
| INT_MAX is assuming every variable is using a 32 bit
| integer which is not always the case. In my experience
| with flight control systems controls systems were focused
| on using the smallest variable necessary for a given
| variable. We had many variables that were only 8 or 16
| bits. The processing overhead wasn't really the driving
| factor for smaller variables it was typically interface
| bandwidth which can be very limited while maintaining
| required safety margins on aircraft.
|
| 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?
| numpad0 wrote:
| So 32767 m/s is like not much short of twice the Solar
| system escape velocity...
| chriswarbo wrote:
| > Sure you could say all velocities need to be in m/s,
| but 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)
| chriswarbo wrote:
| > SI units are great but sometimes they are not great for
| the specific use case. When measuring high power systems
| like power plants or EVs kW/MW/GW are a more appropriate
| unit versus Watts.
|
| 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".
| fnordpiglet wrote:
| I mean what issues would power of 10 fractions have in
| floating point after all?
| sbradford26 wrote:
| If I have data going out on a data bus in grams/second,
| but someone reading that data in a different sub system
| reads it and thinks it is kilograms/second because that
| is the default unit they use then you have an issue. The
| actual conversion of the bits isn't the issue it is that
| certain systems might use different units internally and
| making sure those conversions are done correctly. It is
| much more an engineering design/human interaction issue
| than a computation issue.
| Merad wrote:
| Pretty sure GP was making a sarcastic comment referencing
| how floating point is notorious for subtle rounding
| issues when handling values that have an exact
| representation in base 10 but a repeating pattern in
| binary.
| fnordpiglet wrote:
| Yeah. Given we've moved from counting on our fingers to
| counting on our computers we need a new base 2 metric.
| fnordpiglet wrote:
| Yes, I understood that. However repeated conversions can
| lead to rounding errors such as catastrophic
| cancellation. This is even more esoteric than "grams here
| kilograms there" and thus easier to fall prey to.
| Depending on how precise your measurements are you could
| easily drop significant digits or add random noise,
| especially if you do large scale changes.
|
| https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldber
| g.h...
| sbradford26 wrote:
| Yeah we tended to utilize fixed point for many of our
| variables and documented the precision for each one. Then
| an analysis was done verifying that we were maintaining
| precision through the calculations from input from a
| sensor to output.
| fnordpiglet wrote:
| The problem is almost nothing today accelerates fixed
| point and everything supports floating point
| accelerations, which will speed up your ability to
| calculate the wrong number by many orders of magnitude.
| sbradford26 wrote:
| Yeah that makes sense. In aerospace they will fall on the
| side of accuracy even at the expense of speed. But they
| also tend to utilize FPGAs that can be designed to handle
| fixed point calculations quickly but with that comes a
| lot of cost and specialty hardware.
| fnordpiglet wrote:
| Another place it makes issues is financial modeling,
| particularly for complex derivatives where the model
| might be extremely complex and small errors can
| accumulate into meaningful errors in risk calculations.
| Fixed point is sometimes used in finance but performance
| is also a real concern. There's a lot you can do to
| reduce fp errors if your numerical libraries are
| carefully constructed. But it has often made me wonder
| why there aren't processor lines with high performance
| fixed point since the math is extremely easy - even by
| just shifting the mantissa and working in integer space
| then shifting it back.
| somenameforme wrote:
| I feel like this is a subtle jab pretty much nobody outside of
| serious aerospace enthusiasts is going to get. For those who
| don't know, right now there's sort of a competition for the
| 'next big thing' in rockets. Congress/Boeing/Lockheed have been
| working on the SLS or Space Launch System since 2011. It was
| expected to launch in 2016. It had its first trial launch in
| 2022, and is tens of billions of dollars over budget.
|
| 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] - https://en.wikipedia.org/wiki/Space_Launch_System
| mrguyorama wrote:
| The SLS is mediocre but there are a few things to keep in
| mind:
|
| 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.
| philwelch wrote:
| > NASA needs to keep in house rocketry expertise and the US
| government cannot rely on private companies 100% just for
| like NatSec reasons
|
| 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.
| dotnet00 wrote:
| 1) The US government does rely on private companies 100%,
| SLS is built by Boeing, a private company. Being a private
| American company has very little issue when it comes to
| national security, just means you have them meet various
| requirements (eg only allowing US persons to work there and
| security clearance requirements).
|
| 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.".
| MarkusWandel wrote:
| You can watch the whole thing from the very genesis of the
| turbopump powered liquid fueled rocket. The British did a very
| thorough documentation project on the German A4 / V2 rocket after
| WW2 and it's all accessible to the public.
|
| 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.
|
| https://youtu.be/V_fPdXLx48c?t=2097
| ofrzeta wrote:
| Related: John D. Clark "Ignition!: An Informal History of Liquid
| Rocket Propellants"
| bryanlarsen wrote:
| "It is, of course, extremely toxic, but that's the least of the
| problem. It is hypergolic with every known fuel, and so rapidly
| hypergolic that no ignition delay has ever been measured. It is
| also hypergolic with such things as cloth, wood, and test
| engineers, not to mention asbestos, sand, and water-with which
| it reacts explosively. It can be kept in some of the ordinary
| structural metals-steel, copper, aluminium, etc.-because of the
| formation of a thin film of insoluble metal fluoride which
| protects the bulk of the metal, just as the invisible coat of
| oxide on aluminium keeps it from burning up in the atmosphere.
| If, however, this coat is melted or scrubbed off, and has no
| chance to reform, the operator is confronted with the problem
| of coping with a metal-fluorine fire. For dealing with this
| situation, I have always recommended a good pair of running
| shoes."
| ragebol wrote:
| I could watch stuff like this all day.
|
| 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.
| speed_spread wrote:
| > whatever you think of Musk
|
| 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.
| sangnoir wrote:
| > Musk is a clown but I'll give him one thing: he cares about
| technology.
|
| 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.
| speed_spread wrote:
| I was thinking of pre-Twitter Musk. I'm not sure what game
| the clown is playing now or even if it's a game at all
| anymore. It's so bad that it's almost like a trash artistic
| performance. GG Allin billionaire.
| hoot wrote:
| Did anybody else feel like the musk interview got really
| awkward towards the end? It seemed like he became really bored
| of it and just shut down.
| raylad wrote:
| Tim was trying to be too knowledgeable and not letting Musk
| shine enough.
|
| I would be surprised if Musk gives him another interview any
| time soon.
| localplume wrote:
| He, like most big Youtubers, probably have a large crew of
| people working with them. The article was written by Trevor
| Sesnic, the video was likely edited by others, I don't know if
| he did the graphics, but Tim still did a lot (and arguably did
| the most fun stuff). Smaller Youtubers need to do all of that,
| and from what I've heard editing is the absolute worst given
| how time consuming it is. Many Youtubers struggle with burnout
| centered around how time consuming editing becomes.
|
| 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.
| Gordonjcp wrote:
| > and from what I've heard editing is the absolute worst
| given how time consuming it is.
|
| 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".
| AshleyGrant wrote:
| I support Tim on Patreon. He also utilizes a cadre of Patreon
| donors who provide commentary on early cuts of videos and
| even drafts of scripts. I personally have never understood
| why people would pay to do work for him, but they must get
| satisfaction from it, and the final product is better because
| of it.
| ragebol wrote:
| I'm sure he does. I guess it's like a bootstrapped business:
| you start small and build from there and hire to do what you
| can't or don't want to do.
| MichaelZuo wrote:
| From the about page: > In 2019 the team grew from just Tim to
| a small army of incredible helpers who make this website
| amazing, the videos higher quality, and help foster a fun and
| positive online community.
|
| So the 2017-2019 period where the channel took off was all
| done by him solo, apparently.
| somenameforme wrote:
| I'd also add this standard. Another amazing YouTuber is
| Veritasium. He went from [1] to [2]. The production quality
| is more than slightly improved, but the "spirit" remains
| identical. And I think that spirit is what drives success
| or failure. The production quality is just icing.
|
| [1] - https://www.youtube.com/watch?v=JUJPyQtoB5E
|
| [2] - https://www.youtube.com/watch?v=5eW6Eagr9XA
| Retric wrote:
| Veritasium videos are often subtly misleading which
| really annoys me.
|
| It's great for views, but terrible for science education.
| Diederich wrote:
| Is one example his recent set of videos about how quickly
| electrical energy travels travels?
| Retric wrote:
| Yea, like "Darth Vader killed your father" they are true
| from a specific viewpoint, but people walk away
| misunderstanding what's being described.
|
| 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.
| jaywalk wrote:
| Whenever he drops a new video, I just look for the
| "Here's how Veritasium was wrong" videos to get the real
| story.
| ace2358 wrote:
| It's pretty rough because those 'you're wrong' videos are
| actually just as wrong as he was. The main issue is that
| these complicated topics are difficult to describe
| properly is a 20 min English video that has to be edited
| to be interesting.
|
| 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.
| MichaelZuo wrote:
| Can you link to a 100% correct explanation?
|
| Can be in any format.
| lhoff wrote:
| He recently was a guest in Lex Fridmans podcast.
|
| https://lexfridman.com/tim-dodd/
| dotnet00 wrote:
| Tim's stuff certainly has the information content nailed down
| better than most typical "science" youtubers, but he comes off
| as slightly overexcited at times, which brings up negative
| associations with typical misleading pop science rags for me.
| [deleted]
| adolph wrote:
| To pile on the Tim Dodd praise, be sure to check out his music
| too (which is used in the videos). Solid stuff that reminds me
| of Tycho. So glad he got picked for the Dear Moon mission.
| samwillis wrote:
| > 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.)
| oger wrote:
| It's absolutely worth to go on a tangent here - Tim did a
| great job in explaining Elon (or showing him to the public in
| a probably not too filtered way).
| ragebol wrote:
| Absolutely. Imagine if all journalists had this level of
| depth in all of the topic they covered? I don't think that's
| possible though.
| nordsieck wrote:
| > Imagine if all journalists had this level of depth in all
| of the topic they covered? I don't think that's possible
| though.
|
| 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.
| ragebol wrote:
| Does not fit in traditional media indeed. When I was a
| kid/teen, Discovery Channel, at least in my native
| Netherlands, had some interesting content. I could also
| gobble up something like How it's Made all day. Content
| like Tim's could definitely fit in there too.
|
| YouTube enabled everyone to publish this type of content,
| for good and bad...
| kitsunesoba wrote:
| When I was younger I loved shows like Modern Marvels on
| History Channel that presented the engineering behind the
| various amazing everyday things that we take for granted
| in a format accessible to the layman.
|
| 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.
| prox wrote:
| I agree. You need that intersection of interest,
| presentable qualities (listening, digesting,responding,
| speaking) and quest for accuracy. Hard to get those all in
| one person.
| LargeTomato wrote:
| To be honest he's regurgitating a lot of information. He has
| large gaps in his knowledge but presents himself as extremely
| knowledgeable.
|
| 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.
| sho_hn wrote:
| > but presents himself as extremely knowledgeable
|
| 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.
| peterfirefly wrote:
| > He has large gaps in his knowledge
|
| Yes.
|
| > but presents himself as extremely knowledgeable.
|
| No.
| JshWright wrote:
| Perhaps he has gotten better at that in recent years. I
| got put off his early content for the very that very
| reason and haven't bothered to go back.
| LargeTomato wrote:
| Yeah he has an extreme level of confidence. Tweeting Elon
| about how to architect the landing fins to use "fish
| scale biomimickry"? That's ridiculous.
| 0cVlTeIATBs wrote:
| I was hoping this would be an explanation of the second stage
| failure to ignite three days ago on Japan's H3 rocket.
| LargeTomato wrote:
| I'm surprised at the amount of people who enjoy EDA. I find him
| very irritating. Most people at my small space company find him
| extremely irritating. He is not a rocket scientist. He parrots
| silly buzzwords like "biomimickry" like a fanboy, not an
| engineer. He suggests things to Elon for how to do rockets that
| are just pants-on-head dumb.
|
| His blind fanboyism and arrogance irritate so many people who
| work in space. I'm very surprised HN loves this guy.
| geocrasher wrote:
| His fanboy-energy is too strong, cannot stand him. And I don't
| even work in space. But I do work for a company called Rocket,
| so that's something I guess.
| NikolaNovak wrote:
| Not sure, I have not encountered this author before, but
| frequently in many fields a fan / enthusiast perspective is
| different than professional / expert perspective.
| oh_sigh wrote:
| His audience is fanboys, not aerospace engineers. So it makes
| perfect sense.
|
| He may be a fanboy but that fanboyism got him a trip to the
| moon.
| Diederich wrote:
| > His audience is fanboys
|
| SpaceX fans?
| t3pfaff wrote:
| You can't be in the space industry or even a tangentially
| related aerospace sector and not be a fan of SpaceX. It's
| continuously been 10 years ahead of the rest of the
| industry. The entire industry did nothing but tread water
| for 50 years after Apollo despite massive technology and
| manufacturing advances. The space shuttle was one giant
| deadly 30 year step backwards.
|
| 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.
| apendleton wrote:
| With respect, you and your company of people who are already
| subject matter experts are not his audience; his audience is
| people who are not experts and want to learn about this subject
| matter. Most people on HN are also not subject matter experts
| with respect to rockets, so in that respect, are probably much
| closer to his target audience on average than you are.
|
| > 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.
| sophacles wrote:
| Also, SMEs say dumb things all the time. I know I have in my
| area of expertise. Not so much in "official capacity", sure -
| I try to make sure any presentations or blog posts or
| whatever are accurate. But random ideas I have, or initial
| reactions to some new tech - sure I've shared my really bad
| ideas.
|
| 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)
| WalterBright wrote:
| > subject matter experts often make poor teachers
|
| I find it thoroughly fun to talk with subject matter experts.
| What I learn is amazing.
| apendleton wrote:
| I often do too! But I certainly also had some professors in
| college who were frankly just really bad at conveying their
| expertise in a way that was accessible to people who were
| not also already experts. Some SMEs happen to have good
| communication skills and can be really fun to talk to, but
| the systems that produce experts don't, in my experience,
| select for these attributes, so whether or not you get them
| is pretty luck-of-the-draw.
| Gravityloss wrote:
| Compared to average YouTube, TV or magazine content he is
| excellent and in depth.
| adolph wrote:
| > He is not a rocket scientist.
|
| 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._
| martythemaniak wrote:
| No, he's not an engineer and he cannot build anything, he has
| no special insights or novel ideas. He is an educator that
| popularizes niche and inaccessible knowledge to a large
| audience and that large audience really appreciates his
| efforts. His work in popularizing space tech is a net benefit
| to your industry and thus your company.
| twic wrote:
| I'm comparably bemused by the enthusiasm shown here towards
| some life sciences stuff. HN users are perhaps not the
| discerning polymaths you imagine.
| sho_hn wrote:
| Could you give me an example of his 'arrogance'? I've been
| watching his content for some time, and I'd say he's always
| been very upfront and transparent about being an
| enthusiast/fanboy and not an engineer. His concept is to be an
| audience insert and ask the stuff his non-professional audience
| would ask, as a sort of avatar. I would expect no more
| expertise from him than from myself.
|
| 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.
| LargeTomato wrote:
| I can't find the tweet where he suggests to Elon how to
| design the sides of the rocket. Elon just shuts it down. I've
| never once heard EDA push back on anything Elon says even
| though Elon can say some outlandish things every now and
| then. That blind fanboyism is annoying.
|
| 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.
| valarauko wrote:
| https://twitter.com/Erdayastronaut/status/14426315302249594
| 8...
| kevviiinn wrote:
| HN is mostly software devs, as someone in the bio sciences
| whenever I see comments about my field they're nearly always
| wrong unless another person in the field is commenting which
| isn't very often. It seems like software devs like to think
| they understand things when it's just barely surface level
| knowledge, I don't know why
| nosianu wrote:
| I decided people are just having fun and it's nothing serious
| just water cooler chat and distraction before going back to
| work.
|
| 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.
| was_a_dev wrote:
| I think this is the good, level-headed approach.
|
| I do wish there were active equivalents for beyond software
| development.
| was_a_dev wrote:
| I'm always surprised how quickly a thread than isn't software
| related nose-dives.
|
| 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".
| rpmisms wrote:
| He's incredibly annoying, but he knows his shit. He's like a
| crypto influencer who also happens to be a brilliant engineer.
| I watch his content because it's insanely informative, even
| though he reminds me of every con artist I've ever met.
| ghostpepper wrote:
| Didn't he suggest something to Elon that Elon immediately
| decided to alter on an upcoming rocket? Doesn't sound like he
| knows nothing..
| LargeTomato wrote:
| I forget exactly what he suggested but I remember is being
| like kind of dumb. Elon was humoring him. This guy is
| absolutely not a rocket scientist. He's not even an engineer.
| twic wrote:
| Something about cold gas thrusters?
| https://www.ladbible.com/news/elon-musk-fixes-rocket-
| after-y...
| sho_hn wrote:
| If I recall, Musk was explaining that on the Starship
| booster they had recently begun to use directed venting of
| ullage gases for control authority to save a seperate hot
| or cold gas thruster system and Dodd asked if this also
| applies to the ship. Musk then went "now that you mention
| it, we should look into that". During a visit a year or so
| later he then confirmed they had begun doing it on the ship
| too and that it had occurred to him as he was explaining it
| to Dodd.
|
| 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.
| ghostpepper wrote:
| In my (lay) opinion, this is still evidence that he at
| least has some idea of what he's talking about and not
| all his suggestions to Elon are "pants on head dumb". I
| was never under the impression he actually suggested
| something the team had never thought of.
| lb4r wrote:
| Regardless of you think of him and his 'dumb' ideas, with 1.4
| million subscribers he will probably inspire more people than
| work at your 'small space company' to become real rocket
| scientists themselves. I wouldn't be surprised if he does more
| for the future of space industry than most of those who
| currently work in it individually do.
|
| With that said, if you find him irritating, then you find him
| irritating. Hard to argue with that.
| ivankirigin wrote:
| This makes me want to go back to school and major in aero/astro
| engineering.
| martythemaniak wrote:
| Yeah, I think atoms are just so cool. After almost two decades
| of many different kinds of software, it all starts to looks the
| same and kinda boring. Even LLMs, which are super exciting, can
| barely hold my interested.
|
| 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.
| [deleted]
| punnerud wrote:
| The more I learn about different types of rockets and all the
| engineering behind SpaceX, the more I am impressed by what they
| have accomplished.
|
| Huge thanks to 'Every Day Astronaut' for this YouTube channel, so
| many good videos.
| Koshkin wrote:
| Starting the engine(s) even in a propeller-driven airplane used
| to be a big deal, too. Hell, I'm sure that even starting a car
| engine back in the day was a much more complex affair (than
| simply pushing a button like it is today).
| AshleyGrant wrote:
| Even today it can be a bear to start the engine of a small
| piston-powered aircraft. The vast majority of engines used in
| these aircraft haven't changed very much in the last 70 years.
|
| 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.
| bryanlarsen wrote:
| Check out a video on how to start a model T. It was a two man
| job: one on the inside fiddling with spark timing, the other on
| the outside cranking it over. Often you also need a bit of
| priming (aka choke).
| MS90 wrote:
| Yes, early cars had to be started with a crank handle that
| stuck out of the front of the grill, similar to how early
| propeller engines had to be hand-spun to get going. Apparently
| if you didn't crank it quite hard enough the handle could snap
| back at you rather violently, one of my great-grandmothers had
| her arm broken this way.
| WalterBright wrote:
| With the piston engines they had to be turned over by hand
| first to let the oil drain out of the cylinders before
| starting them by pulling on the propeller.
| h2odragon wrote:
| > the handle could snap back at you rather violently
|
| 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.
| jackmott42 wrote:
| Those things really are fundamentally easier, which is why it
| became routine and something every day people could operate day
| in day out pretty quickly. Rocket engines are still very hard
| to do 70 years later.
| bryanlarsen wrote:
| Starting a modern car engine is not easy. They've got high
| compression ratios and are other wise tuned for high
| performance and fuel economy making a sustained ignition
| difficult. It's the computers and other timing components
| that make it seem easy and everyday.
| lsllc wrote:
| They used to use what were basically shotgun shells with no
| pellets to start airplane engines -- it was called a Coffman
| engine starter (it was actually used as a plot device in the
| movie Flight of the Phoenix).
|
| https://en.wikipedia.org/wiki/Coffman_engine_starter
| oger wrote:
| Definitely among one of the great pieces he has produced. Highly
| informative and educational. He really finds the right tone and
| this long piece never gets boring for a second. Also from a
| production perspective his animated engine charts are top and
| visualise the point he is making. BTW his interviews with Elon
| Musk at Starbase are also a must see (some clips included in this
| video as well). You really start to see and understand how Musk
| works - and it's not as bad as media is trying to make him. His
| engineering principles are really interesting and can be applied
| to many scenarios. It's this level of abstraction that makes the
| difference and gives him a competitive edge.
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