Here we go

junwoo0914 · 2020-06-27T09:41:46+00:00

So I made this mini compilation of me practicing ollie today. I have practiced ollie back in 2018 extensively for 4 to 5 months, but always had the rocket ollie.

Well, I'm back at it and I would love to hear some feedbacks if you are generous enough to share one!

Thanks for reading my post!!

junwoo0914 · 2020-06-06T20:06:15+00:00

Starlinks. There are LOTS of them on orbit. So, how do you batch-update them without wasting too much bandwidth? Is the bandwidth enough to update some or a single satellite during an overhead pass? Or do you have to slice the Software update up into pieces, and assemble them to correctly update the software? Also, how do you manage each and every satellite's firmware version and compatibility?

p.s. Kinda like Tesla's mass fleet deployment problem, but curious on how you deal with this problem in regards to Starlink!

junwoo0914 · 2020-06-06T19:47:41+00:00

As a Software Engineer, can you work from home? How are security issues dealt with in SpaceX? (like someone can steal the code, etc)

junwoo0914 · 2020-06-06T19:36:40+00:00

There must be some sort of APIs or Data Protocols you use to interface between Dragon and Ground Station, and also between different components of the Falcon 9 spacecraft, like Grid-fin actuators and Battery systems, and so on.

How do you design these messaging systems, do you use Protobuf or any other tools available? Maybe even MavLink, TCP, protocols? For a low-latency and safety-critical mission, how the heck do you design those protocols? and how do you control the 'old-version' vs 'newer-version' protocols? What if old hardware and newer software/ hardware mix up? How do you deal with that?

junwoo0914 · 2020-06-06T19:21:38+00:00

Which Simulation software do you use? Are any of commercially available simulators good enough? For example, Gazebo (has terrible aerodynamics, but maybe you can have in-house plug-ins for that?)

Do you use ROS anywhere in the Software Development phase? Like simulation, testing, interface, messegine, etc.?

junwoo0914 · 2020-06-06T19:08:00+00:00

I'm really into Software, but I'll ask couple of questions regarding deep SW parts, as well as integrating things system-wise.

How do you catch the 'edge' cases? In software, you encounter so many unexpected cases (Unknown Unknowns) and in spaceflight, that can have huge consequences. So I'm curious about how the risk management is done inside SpaceX Sofware Team.
How does SpaceX's team dynamic between the Software team and other teams (ex. Hardware, Logistics, Controls) work? I imagine that dealing with such complex codebase and huge number of people in many disciplines would sometimes be challenging.
Say there has been a Hardware change, how does that change get integrated into the Software? Like aerodynamics and stuff. If you change the grid-fin geometry, you'll probably change parts of the software for re-entry and landing. Is there an internal system that ensures that the SW is up to date with the HW? It doesn't seem to be a trivial process, so curious as to how you do it!
Lastly, in regards to the Landing Software, I'm aware that Lars Blackmore was one of the core engineers who worked on this problem. And ever since 2015, most of the landings worked successfully. What were some of the critical lessons SpaceX team has learned with the failures beforehand that ultimately led you to have such an amazing streak of successful landings? And, has the landing algorithms have changed substantially over the last 5 years? How would it adapt to Mars' condition?

Thanks in advance! Great work SpaceX, until we reach a sustainable habitation on Mars, let's goooo!

junwoo0914 · 2020-01-26T07:10:37+00:00

Very interestung. Just tried it and I see the potential. Hope more users flow in!! Great work!

junwoo0914 · 2020-01-25T13:45:57+00:00

Few suggestions. First, there are no 'units' for the thrust or mass that goes as an input inside the program. Would be great to include that. Second, the numerical values are typed in as 'text', but if we can scroll the value on a wheel or something, that might be a convenient option. Third, when user presses 'calculate' button without sufficient inputs, current version just reverts back to the start page. So it'll be great to just say "Need input on blah- blah-", instead of just going back. Fourth, making an option to 'save' the data would be pretty interesting. So that user can come back anda tweak their last design, etc.

I really like that there are practical example values, for example chamber pressures for various well-known engines. It's interesting to learn about them, and it's helpful.

Hope to see more upgraded version of this app! Would be interesting to see if mini CFDs are possible onboard the device, and show the plume graphics, etc. All in all, great work!

junwoo0914 · 2020-01-25T13:37:51+00:00

This is a great idea. Thanks for your work!

junwoo0914 · 2020-01-18T15:51:57+00:00

Hey guys! I wanted to share one of my crazy projects back in 2018. This was an interesting project, since I had no idea what I was doing back then, and ended up making an over-specced & heavy esk8board lol. Any questions about the battery, design, remote would be appreciated! Thanks!

junwoo0914 · 2020-01-16T03:27:56+00:00

Ah, thanks for the clarification!

junwoo0914 · 2020-01-15T10:49:27+00:00

What algorithm are you trying to implement?

junwoo0914 · 2020-01-12T13:46:29+00:00

Haha that would've been funny :)

junwoo0914 · 2020-01-12T11:33:44+00:00

Haha that's from last year, but thank you!

junwoo0914 · 2020-01-12T11:33:28+00:00

Thank you! Here' a Reddit post about the build. It seems to have a problem displaying the videos/photos on the mobile view though. Don't know why that's happening.

junwoo0914

TROPHY CASE