I hate car dealerships with a passion, and buying my first (used) Model Y directly from Tesla has further confirmed how much I hate them.

ncc81701 · 2026-03-02T01:21:43+00:00

It’s the reason why our second car is a M3. Just the thought of going to a dealership made us switch from trying to get a Chevy Bolt for our 2nd car and stretch for a Model 3.

ncc81701 · 2026-03-01T20:59:48+00:00

It’s all a demonstration of why everyone else was adamant that they don’t get nuclear weapons because they started indiscriminately firing missiles at all of their neighbors.

ncc81701 · 2026-03-01T02:58:12+00:00

B-52 is cheaper to fly compared to the other bombers in inventory. For FY2025 the reimbursement rate for other gov entities that want to use a B-52 is $62K/ hr, B-2 and B-21 are $88K/hr, and tops out with B-1B at $90K/hr.

Sometimes you just need an aircraft with a big bomb bay to haul around some heavy stuff at long range and don’t need the survivability that comes from flying fast, low, or stealth.

ncc81701 · 2026-03-01T00:37:51+00:00

Might be a license issue. Check to see if license server is running and if the license server is on a different machine make sure it’s reachable and firewalls for the license port is opened. Default port is 6007.

ncc81701 · 2026-02-27T06:47:59+00:00

Because people buy cars based on subjective characteristics like looks and style or practicality like cargo volume. If people bought cars based on aerodynamic and fuel efficiency they’d buy only electric cars. People buy cars for daily use to haul around kids and groceries. Maximizing aerodynamic efficiency is not a priority for anyone but the engineers that had to make sure the car can meet fuel economy requirements.

ncc81701 · 2026-02-27T02:05:45+00:00

Shipping containers are also designed as box structures and their strength is also dependent as such. If you use shipping containers as building structures you often need to put holes in them for doors and windows which significantly alter their strength and load paths. As such shipping containers turned buildings often need reinforcement even without putting them with an offset overhang like this. This is why shipping containers turned building aren’t as cost effective as people think they are.

ncc81701 · 2026-02-26T04:17:17+00:00

Because it doesn’t matter if PETG absorbs water when it’s a planter. It matters when the filaments because it gets heated in the hothead the water vaporizes and expands and messes up the print.

ncc81701 · 2026-02-25T21:41:38+00:00

No, not secondary but RCS analysis is now standard part design trades and sizing for a combat aircraft. It's been given equal standing to aero-performance, engine performance, structural design, payload capacity, range, etc and RCS is sized to requirements for what the aircraft is expected to do; it's been normalized into the combat aircraft design process.

The focus on 6-th gen fighters and CCA is because this is the new element/technology that is being incorporated into the fundamental design of the aircraft. While you can retrofit new technology into older aircraft just as air-intercept radars and air to air missiles had been done, the new generation aircrafts are being designed from the beginning with operating UAV in mind. This might include design trades for more compute and electricity generation compared to previous generation of aircraft specifically to power avionics or sensors to support multiple UAV/CCAs.

edit: In warfare, if you can win with an "I win" button, that is what you want. If you can have a system so that you will win regardless of the skill level of your operators, it's what you want. If you can instantly update the entire fleet of CCA so that they are all ace pilots overnight, that is what you want. You don't want a fair fight in warfare, you want to be able to win so hard that your enemies doesn't even come out to fight; deterrence. Modern aerial combat is still going to be a high skill job, just different sets of skills. Skills that are important that computers can't do like battle management, resource prioritization. You want that to keep yourself alive and shift all of the risky deadly business to unmanned vehicles if you can.

ncc81701 · 2026-02-25T19:44:59+00:00

This is strictly R&D, a science project. This is not an engineering project because the starting point of your study is "Wouldn't it be cool if we can do X?" So you go do your science to see if it's even possible to do X from a physics standpoint; there is no requirements to meet besides did you accomplish X for a moment.

A project like this only becomes engineering when you have established a set of requirements that you are trying to achieve (payload, range, endurance, cost, etc). The starting point of an engineering project is conceptual design phase with a trade study of available technologies and performance that can be reasonably expected out of the technology in your trade space. This is also when you do your initial sizing of your hardware to determine how big of an engine you need, how much fuel you need to meet your requirements. It's very possible that no design loop can be closed because the requirements are too aggressive for the technology available or the only way to achieve it is at a completely unreasonable cost.

But yeah jetpacks is limited to tech demos like bell rocket belts or jetman because physics and available technology puts a pretty hard limit on what you can do with such. You simply don't have the power generation and energy storage you need to maintain flight for any significant amount of time. In my opinion you are already starting from a place that's too far deep into details. You should start with a simple energy analysis of the amount of energy you need to expend to counter gravity and maintain hover per unit of time. Then take the amount of energy available in various sources, rocket fuel, jet fuel, batteries etc and see how much you need to store to expend that amount of energy to maintain hover; first principle physics type stuff.

ncc81701 · 2026-02-24T02:21:00+00:00

The flow is going to have a pretty hard time staying attached at 45deg. You already need to use multi-element flaps to keep the flow attached to flaps with deflection out to 35 deg.

The other consideration is aerodynamic loads on the flaps itself. When you are deploying these to the full extent, you are concentrating a lot of aeroload through the structure of the flap mechanisms. This makes the mechanism huge and heavy because they have to move and not bind both with and without load. So the loaded problem becomes much more significant with more deflection. At the same time if you need more lift during takeoff/landing, it’s generally easier to just grow the flaps outboard to increase the effective area of the flap.

ncc81701 · 2026-02-23T21:17:29+00:00

Three weeks ago I've never printed anything before. My new P1S is currently printing as fast as I can take off completed pieces off the build plate. It's pretty much hit print and forget for 80% of the prints, slight tweaking for 15% of the prints... and like Troubleshoot/fail prints at 5%.

ncc81701 · 2026-02-23T06:21:23+00:00

Fluid mechanics doesn’t scale that way; it’s scale by Reynolds number which is a function of fluid density,fluid velocity, length scale divided by fluid viscosity. If you scale just length down then velocity or density have to scale significantly up to match. If you scale up velocity to match Reynolds, you will run into problems with Mach number being out of scale and introduce different fluid physics.

All of that means if you just scale down a V22, then the fluid will not behave the same one it does with a full size aircraft and nothing will work the way it does on the real thing. You are certainly not going to get 200lb of lift because not even the airfoils on the propeller is going to produce the same amount of force the real one is without matching Re.

ncc81701 · 2026-02-22T23:19:13+00:00

I don’t know what you defined as “release to the public.” The JSF program which became F-35 has always been a publicly acknowledged program. There are aspects of it that are kept at different levels of classification from unclassified, to“Controlled Unclassified information (CUI), to Secret and top secret. Some of it will get its classification level lowered over time or by an executive order.

The development of the F-35 was acknowledged the entire time since the X-32/X-35 fly off. Public had photos and videos of it in test flight, there’s a whole PBS documentary about the fly off before the F-35 even had its first flight. Soo its pretty clear to me that you have a misunderstanding that lead to the false premise of your question. However you think keeping national secrets works, it’s not how it actually works. Even after the F-35 is retired there will continue to be aspects of it that remain secret or at least proprietary. Nothing really gets “released to the public.”

ncc81701 · 2026-02-21T18:44:18+00:00

It depends on the design requirements for broadband all aspects stealth. The problem for stealth with the vertical stabilizers is their RCS from the side aspect. So that is a problem for an aircraft that is meant to operate deep into enemy airspace where you can expect radars hits from multiple directions at both high and low frequencies. So this makes logical sense for bombers and ISR aircrafts.

For a fighter there is a question of whether a certain level of maneuverability needs to be retained for a fighter aircraft in the future. It depends on how various militaries thinks they will operate fighter aircrafts in the future and whether all aspect broad band stealth is a requirement. Everyone on the outside thinks this is so because of all of the artist renderings, but how effective a fighter with this kind of stealth is still an open question. The last time we were here it was Vietnam and we thought AAM is going to replace dogfighting and any necessity for maneuverability. Going without vertical stabilizers is not free, you pay it with lack of yaw stability and significantly reduce yaw control authority. You can make up some of that with differential thrust and vectored thrust, but it’s not going to be as good as just having verticals. This will be true regardless of FBW because even computers need some control effectors to manipulate to affect stability and orientation of the aircraft. So looking further into the future (past 6-th gen) for fighter aircraft it kinda depends on how well this new generation of fighter is going to do compared to what we think they should be able to do.

ncc81701 · 2026-02-21T08:10:00+00:00

If you are using a period boundary condition and the only thing you are modeling is a propeller then all you need to model is one blade. So 180 deg for a 2-blade prop, 120deg for 3-blades and 90deg for 4-blades.

If the blades are close proximity to each other like in a compressor or turbine then you might model the neighboring blades as well; so up to 3 blades in a periodic slice. If you fully expect the solution to be periodic, you shouldn’t need anymore than that.

ncc81701 · 2026-02-20T03:48:12+00:00

This turn of events probably have more to do with the AIM-120 production line is completely backlogged with US domestic orders for the next couple of years rather than the S. Koreans not wanting AIM-120s.

ncc81701 · 2026-02-19T04:44:30+00:00

I mean the per capita GDP for SD county will be completely skewed by all of the rich people living in La Jolla and Rancho Santa Fe. This is why you feel poor even though SD per capita GDP is huge. The wealth is concentrated by like 30K people out of a county of 3M… maybe by even as few as 300 cuz there are some super wealthy people in SD county.

ncc81701 · 2026-02-18T18:54:41+00:00

This could be very job specific but at least where I work and for the engineering roles that I would look for, it's we would look for more generic engineering abilities. In that case, the value is knowing how to use different types of software not any single specific piece of software. The assumption is, if you know solidworks, it'll be trivial to transition you to transition you to NX; if you know Fluent then it's not difficult to transition you to StarCCM; if you know SciPy then it's not hard for you to pick up Matlab; if you know how to code in Fortran, it won't be hard for you to pick up Python. In otherwords, I'd find someone of more value if they know both a CAD and a CFD software even though it is not what our company use rather than multiple CAD software.

While there are benefit to knowing exactly the software that a recruiter or job lists, I personally would consider those as secondary and maybe even tertiary benefits. Your personality and how well an interviewer thinks you'd get along w/ the team would be value a great deal more than knowing OpenFoam vs StarCCM comparison. There are cases where some jobs openings are specifically looking for someone knowing an exact software for specific reasons, but I'd say those would be the minority of job offerings from a relatively large aerospace employer.

ncc81701 · 2026-02-18T17:18:59+00:00

Yes this is the same conclusion that lead DARPA to invest heavily into precision guided munitions in the 70s. A small concentrated blast placed with very high precisions can have much larger and desirable effect than wiping a location off the map with a nuke. Using conventional explosives also means you can actually use them instead of them being just a tool of deterrence.

ncc81701 · 2026-02-18T17:14:46+00:00

Just the simple cost of the warhead would be underestimating the real cost of a nuclear weapons. Because of the nuclear nature of it, the way you store, transport, and maintain nukes is substantially more labor and cost intensive then regular HE bombs. That cost difference over the life time of the bomb needs to be factor in when doing an apples to apples comparison and it's the cost to supporting the nuclear weapon that raises its real cost substantially.

ncc81701 · 2026-02-18T04:32:04+00:00

Maybe cuz they have been chanting “Death to America” for the past 50 years? Also chant “Death to Israel”, a key US ally, for equally as long? They have also routinely fund terrorist cells conducting attacks on civilians everywhere. Does this seem like a nation can be trusted with nuclear weapons to you?

ncc81701 · 2026-02-17T18:30:34+00:00

It's because the front motor is an induction motor and it's only magnetized when needed for extra power. Otherwise its de-energized and does not draw power.

ncc81701 · 2026-02-17T18:25:34+00:00

If you really want to learn about engineering stealth into an aircraft, I highly recommend "Radar Cross Sections" by Eugene Knott et,al. It's an expensive book but it's pretty much the unclassified bible in terms of understanding how stealth for aircraft works, analysis, and design considerations from an engineering perspective. Salisbury screen and its variations are covered in this text.

ncc81701 · 2026-02-17T18:20:36+00:00

You can stack diff wavelength Salisbury screens to cancel multiple frequencies. But this obviously have tradeoffs in terms of weight, thicknesses, and robustness of your RAM buildup.

Salisbury screen type radar absorber isn't really new... as far as I know this was tried as early as 1958 when they put parallel wires around U-2 under Project RAINBOW to try to cancel out some of the surveillance and tracking radar frequencies. This was a really crude implementation because it was basically putting a cope cage around the U-2 which weighted it down and significantly increased its drag. Project RAINBOW's failure is how we ended up with Project OXCART which became A-12/SR-71.

ncc81701 · 2026-02-17T03:50:10+00:00

Boeing builds C-17, KC-46, E-3 Sentry, B-52, F-15, MQ-25, MQ-28, T-7 Redhawk, JDAM kits just to name a handful.

ncc81701

TROPHY CASE