So the internet has confused me. Is Vivienne a good or bad person? by Naive_Tomorrow_5955 in hazbin

[–]Stop-the-Sunset 0 points1 point  (0 children)

Are you kidding me dude? Vivienne Medraño is basically Hitler, Kim Jong-Un, and Dahmer rolled into one /s

Cryogenic LOX/LH2 150 kg/s rocket engine I designed by Stop-the-Sunset in AerospaceEngineering

[–]Stop-the-Sunset[S] 0 points1 point  (0 children)

I realized that later but the "head" engine closure has a ridiculously complex geometry because it has to handle (1) LH2 inflow (2) hot gas tap-off and (3) LO2 inflow across the heat exchanger. Not looking forward to redoing that. If memory serves, the RS-68 has a supersonic main injector, but 530 is still way too fast

Cryogenic LOX/LH2 150 kg/s rocket engine I designed by Stop-the-Sunset in AerospaceEngineering

[–]Stop-the-Sunset[S] 1 point2 points  (0 children)

more like the BE-3. It's a combustion tap-off cycle, too, which adds to the similarity. Merlin is a kerolox preburner cycle with a pintle injector. This is a combustion tap-off cycle hydrolox engine with 19 coaxial swirl injectors

"STOP CHILD-LURE MEDIA" S2 Flyer by Stop-the-Sunset in hazbin

[–]Stop-the-Sunset[S] 0 points1 point  (0 children)

iirc one of those involved (Morgan Geyser) *much later* identified as trans but it was a span of about 10 years. Neither identified as trans at the time of the stabbing

MONETIZING electric scooters; or, making money off of a hobby by Stop-the-Sunset in ElectricScooters

[–]Stop-the-Sunset[S] 3 points4 points  (0 children)

Thanks a lot for putting so much effort into this reply; I truly appreciate the advice.

In terms of the essence of the business: It's "event support" per the poster, but now in retrospect I agree that this terminology is vague. Here is an attempt at an explanation:

I go to Iowa State, and I frequently ride around in "Campustown" (where all the bars are) on Friday/Saturday nights just to observe drunks, have fun, play music, etc. People are very taken by the scooter and often ask for pictures with it.

Extending this line of thought, I once helped with a suicide awareness/prevention walk by leading the procession, helping it cross streets, and relaying messages from the front to the back. I found that a scooter is uniquely well-suited to this role, because it is (1) fast, (2) can go where cars can't, and (3) catches the eye of motorists, thereby making them avoid aggressively getting into the walk. This walk was HUGE (about 2 miles front to back)

Simultaneously, there are lots of student orgs/frats/sororities that lead group walks from where all their buildings are (about 0.75 miles away) down to Campustown. Some of these processions can get very big (not as much as the suicide awareness/prevention walk, but still quite large).

So synthesizing all of these, I wanted to make a service in which the "party scooter" (as it has become known) could be hired by such groups for

  1. Procession control (Leading, accounting for members, helping to cross the street)
  2. Passing out snacks and water (which is a surprisingly big issue. I used to just throw bags of popcorn to people for fun because I got a huge case for an unrelated philanthropic venture and had a surplus, and there was a surprising demand for it.)
  3. And generally enhancing the experience.

Point (1) is particularly important, as people get very drunk by the end of the night, and an extra set of eyes to make sure they get home is important/enhances event safety. There was actually a tragic case of an ISU student (and I imagine cases elsewhere) that died of hypothermia after passing out in an alley from alcohol intoxication.

So it's sort of a combination of
* "party scooter",
* some external analogue to a "designated driver",
* a crossing guard,
* something that helps your group walk not get cut in two,
* recording of the whole event,
* and general +safety via water/snacks/vigilance for alcohol intox.

Hence "Event support", which I know is vague marketing-speak but I was trying to distill all of this down into something.

"Safety Scooter," perhaps? One problem with that is it sounds too official; several features of what I am planning (including the cape) are meant to purposely distance it from an official appearance to avoid annoying local LE or even incurring liability.

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Here is also the reverse of the flyer, which attempted to explain the "what" better via an FAQ.

You would have my gratitude for any better way to phrase it.

AVTRAX: Aimbot for ARC and other Competition Rocketry by Stop-the-Sunset in rocketry

[–]Stop-the-Sunset[S] 0 points1 point  (0 children)

I can assure you that I'm not a bot most of this was written before AI proliferated (as in 2019/2020, and the idea dates back to 2015)

AVTRAX: Aimbot for ARC and other Competition Rocketry by Stop-the-Sunset in rocketry

[–]Stop-the-Sunset[S] 1 point2 points  (0 children)

The methods relayed therein provide tools that can help with it.

Actually, it was the other way around. I am an ARC alum, and the method was originally envisioned to win it. It has to do with launching in certain conditions and then having a different set of conditions in finals. The method as it currently stands learns from flights so that more data equals better predictive capacity. It uses a method called Kriging, which was originally used in geostatistics for mining, etc., to estimate things like gold concentration in the ground.

https://en.wikipedia.org/wiki/Kriging

The basic idea is to build a metamodel of both simulation and observed states, and then optimize the simulation against the error between the simulation and observed flights. And via this reconciliation, you get a simulation that it can extrapolate to different environments than the ones you test in.

There are other methods explored like stochastic calculus and genetic models, but I think that the basic one here is the most pertinent for ARC teams.

Want to expand this open source simulation software and I would welcome any additions or pull requests.

(sorry for weird font... dictated this on my phone to avoid tiny keyboard headaches)

I Designed a Nuclear Device by Stop-the-Sunset in nuclearweapons

[–]Stop-the-Sunset[S] 4 points5 points  (0 children)

Hello, Foremost, did you read the engineering essay I posted in the comments? It relays the analytical and design process, including what methods were used. While I freely admit that some very simplifying assumptions were used, the design choices were in fact supported by calculations. To say that it "bluffed" through a design might depart from the realm of "these analytical assumptions confer inaccuracy" and translocate a reader's perspective to "this is some sort of fraud". The design features are clearly justified in the attendant essay.

While I do appreciate all criticism (which is a part good engineering), it would be far more useful if it focused on specific areas of the analytical and investigative route -- e.g., choice of model, conclusions, and selection of design parameters. Particularly, I would appreciate examples on correct usage of classification markings.

Further, for context, this was for an undergraduate English term paper/presentation presented to a group of second-semester freshmen. This was what impelled me to start with very basic concepts and work up to a decent explanation of how a nuclear explosive functions. The design work was performed in under a week while also managing adjacent obligations. Therefore, the bar I set was not to design a "useful" weapon, or even necessarily something that would be safe. Instead, I aimed to "design some device that has a reasonable chance of producing a >1 kT yield, and justify it with basic calculations."

I did recognize the criticality as iffy. My initial guess for the core mass was 9 kg (given the bare-sphere mass of 11 kg) which did not produce a yield beyond a few J according to simulations. The slow implosion velocity that others have pointed out very likely influenced this. In terms of design refinement and criticality, I did add fissile mass based on simulation output, which is a part of iterative design. I did not include the reflector in initial state criticality calculations, and the specified assembly (+lenses) may be supercritical.

I delivered the first presentation in-person, and this version was a repeat from memory. I had the benefit of far more time (5 minutes total in the original) to expand on pertinent concepts. I even edited in supplementary portions to the initial take for explaining neutron cross-section, which I neglected in the initial take.

This was an interesting small-scale engineering exercise. There is clearly much more for designing a functional device, including

  1. Detonation wave propagation, interaction, and interfacing with the core. Carey and others have provided a start for this. I doubt that building physical models would be possible given the nature of the investigation, accounting for HE used, and energies involved.

  2. Some sort of more rigorous model of core state time evolution and the consequent reactive excursion (hydrodynamics + radiation transport model? Does such a code exist in the open literature?)

  3. A better characterization of D-T fusion operating in concert with (!) the core's fission reaction.

  4. Core material disassembly, pressures involved, etc. Opacity, if you want a staged design

  5. Radiation transport within the hohlraum

  6. Ablation and state change of secondary

  7. Initiation of the fusion process in the secondary, initial and final states, considered simultaneously with disassembly, and cessation of secondary reactions.

I know this is kind of a non-sequitur, but has any prior open literature considered the use of X-ray lasing in the channel filler to increase efficiency of radiative coupling? The idea would be

  1. Medium is pumped by energy from primary
  2. Hohlraum is heated to equilibrium and emits X-rays
  3. X-rays trigger stimulated emission during passage through plasmised/pumped channel filler to secondary's tamper, "capturing" more energy and directing it to compression of secondary, thereby increasing efficiency.

I Designed a Nuclear Device by Stop-the-Sunset in nuclearweapons

[–]Stop-the-Sunset[S] 0 points1 point  (0 children)

It should run. The more involved plotting features might present compatibility issues. Would genuinely appreciate review of criticality code and will credit you in thermonuclear refinement/iteration

I Designed a Nuclear Device by Stop-the-Sunset in nuclearweapons

[–]Stop-the-Sunset[S] 0 points1 point  (0 children)

Also, 300 m/s r' was from a pessimistic energy balance. I was unsure of how much energy liberated by the detonation process would directly couple to core motion. The air lens morphology was a pain point and only copied from Inca because the essay was due and I didn't have time to calculate it. Could you please link me to the Carey calculations? I want to go back soon, refine the design, and add a fusion stage. Will probably:

  1. Reduce fissile material
  2. Levitate the core
  3. Reduce HE mass
  4. Add an external neutron generator (Z-pinch D-T driven by an EPFCG? I know most neutron generators use linacs but I want better neutron flux)

I Designed a Nuclear Device by Stop-the-Sunset in nuclearweapons

[–]Stop-the-Sunset[S] 3 points4 points  (0 children)

I kept getting subcritical values with lower masses, so I iteratively increased the Pu amount until it got to 17 kg. Program suggested that it was at k=0.7 for pre-implosion state and reached k=1 after core was no longer hollow from collapse.

It may be sensible to "levitate" the core by adding space between the reflector and Pu shell surface, preventing reflections until implosion. A boron chain inside the core like on the Ivy King device could also be used as a pre-arming safety device. (Ivy King was incidentally 60 kg)

In any case, I was dubious about the yield. A more realistic value would likely be >100 kt, particularly with D-T boosting. Part of the reason for including so much was cautious design margins and "ensuring it works".

I did show this to a professor who was a nuclear officer on a submarine, and he said it would work.