asdfadsfgfdda's comments

One slight advantage: you can store liquid nitrogen. So, you can use cheaper electricity to produce it

The engine load is probably a steady, consistent magnitude. While a landing load is rapid and variable. Also, you need to design legs for wind loading after landing, which can be high if you want to launch often.

or its shiny because vacuum hardware is routinely electropolished?

I think the original plan was to convert the heat back into electricity with a turbine. So the higher temperature of sand would greatly improve thermodynamic efficiency.

Yes a storm could damage the coal plant with some small probability. But now you have replaced the coal plant with batteries + solar. Solar will be disabled by every large storm due to cloud cover. The grid will certainly be less reliable.

Pilots still fight turbulence today, usually by changing altitude. If this system allows the plane to stay at optimal (but turbulent) altitude, it could save fuel.

Stainless steel has its own safety issues (hexavalent chromium exposure from welding or grinding)

Private car insurance companies are pretty sophisticated, so they certainly know if a certain vehicle is causing higher claims and will price accordingly.

But, IMHO, the legal minimum liability insurance policy is way too low. A serious car accident could easily cause millions in personal injury damage. Most US states require only ~$50k personal injury coverage.

It's not just a passive payload, these targets have radio transmitters. So the task is probably easier.

Quad-engine jets are automatically ETOPS-180

https://www.boeing.com/commercial/aeromagazine/articles/qtr_...

In theory, a faster airplane is more productive (fly passengers farther in the same amount of time). So crew and capex costs are lower per mile. Maybe a crew can fly New York-London and then fly back, vs a subsonic airliner with a crew that flies one way, stays a day for crew rest, then flies back.

There are many in CA that are ridiculous. Most are not related to safety, but likely due to lobbying from some industry.

Fire sprinklers are required in single family homes. The very small incremental safety benefit is far outweighed by the initial cost, maintenance cost, and potential failures (more plumbing to leak). If you really wanted to improve fire safety, make it cheaper to replace 1950s-era houses with new construction!

Solar panels are required for new homes, which ironically adds a small amount of fire risk (like all electrical devices). This is required in areas with cloudy conditions, or houses that are shaded by trees. The cost per watt is ridiculous compared to how cost-efficient utility scale solar has become. Not to mention the safety risk to solar workers on a second-story house.

Just in plumbing code, there are several ridiculous restrictions. Some jurisdictions allow air admittance valves, others do not at all. ABS pipe is illegal for commercial buildings, but just fine for residential. IPC allows 1.5" vents for toilets, but UPC requires 2".

>The mobile microreactor would be coupled with a power conversion system that generates approximately 1 to 5 MWe using an open Brayton gas cycle

https://www.cto.mil/wp-content/uploads/2022/05/Final-EIS-Vol...

Sounds like an air compressor+turbine, but heated by a heat exchanger instead of burning fuel.

These are gas-cooled reactors, and much lower power output. Existing designs for Navy reactors are all pressurized water reactors that produce hundreds of MW.

There's also a challenge in waste heat. Ships have basically unlimited seawater, but they are probably designing this to use minimal (or no?) water.

Most fuel for aviation is jet fuel, and there already is a "drop in" approved biofuel available:

https://www.faa.gov/about/office_org/headquarters_offices/an...

The real answer is: look at their workforce. Their workforce has all the power in negotiating.

https://philip.greenspun.com/flying/unions-and-airlines

Depends on the customer. An occasional (1/year) flyer? Probably not. A frequent flyer? Yes, by direct observation and indirect anecdotes. There are also very sophisticated customers, like large businesses. They definitely look at cancellations and delays when selecting an airline.

It's a glider, but a glider capable of mach 3 flight. So, approach speeds will be much faster than a typical glider. Probably higher speed than an airliner. That would be dangerous to land off field.

Also, it could mean the vehicle is exposed to aerodynamic conditions it is not designed for, operating outside of the flight envelope.

The linde cycle is not used industrially, they are using a reverse brayton cycle. This cycle use air as the refrigerant, and is probably the most widely distributed industrial cycle in the world (because liquified gases do not transport easily).

They likely use air as the refrigerant, like most air liquefaction plants.