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How to start a rocket engine

everydayastronaut.com

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Re: How to start a rocket engine

#41

Post by AshleyGrant »

Koshkin wrote: post #16

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).

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.

Re: How to start a rocket engine

#42

Post by ragebol »

localplume wrote: post #5
ragebol wrote: post #2

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.

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 w…

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.

Re: How to start a rocket engine

#43

Post by sbradford26 »

chriswarbo wrote: post #31
sbradford26 wrote: post #19

Earlier quoted context omitted.

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…

> 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/wiki/Coherence_(units_of_measuremen... - There is only one unit for ea…

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.

Re: How to start a rocket engine

#44

Post by ragebol »

nordsieck wrote: post #36
ragebol wrote: post #9

Earlier quoted context omitted.

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.

> 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.

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...

Re: How to start a rocket engine

#46

Post by hoorayimhelping »

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

Re: How to start a rocket engine

#47

Post by fnordpiglet »

sbradford26 wrote: post #38
fnordpiglet wrote: post #21

Earlier quoted context omitted.

I mean what issues would power of 10 fractions have in floating point after all?

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…

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_goldberg.h...

Re: How to start a rocket engine

#48

Post by dotnet00 »

ragebol wrote: post #2

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.

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.

Re: How to start a rocket engine

#49

Post by LargeTomato »

samwillis wrote: post #3
ragebol wrote: post #2

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.

> 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 passi…

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.

Re: How to start a rocket engine

#50

Post by LargeTomato »

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.

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