I am taking a trip soon to London and will possibly be adding a couple days in Paris. It's been a hot minute (few years) since visiting the UK and would like to solicit some timely advice and tips. One thing that comes to mind: How important is it to carry cash? Would I need to pay London and Paris street vendors or any shops with cash or will a card with no exchange fees suffice? While we will of course be visiting some tourist attractions like museums, most of our time will be taken up with book stores, record shops, food and coffee shops.

I've been following tildes the past couple of weeks, and am really enjoying the friendlier, more thought out discussion, when compared to reddit. The one thing I miss is r/flying, which was a pretty decent community of pilots without too much low-effort content.

I'm curious if any other pilots have migrated here (hobby pilots, or professionals)? Are we anywhere near critical mass to support discussions around it?

To keep this valuable to the community at large, just a bit about flying as a hobby. At-least in the US, we still have one of the most active General Aviation communities in the world. It's a lot more expensive than it used to be, but for around $10k you can earn your Private Pilot rating. With that you can fly to nearly any airport, over nearly any area, see beautiful views, experience all sorts of weather and locations. At that point you're looking at ~$100-200/hr depending where in the US you're located, and what sort of club or rental you use.

It's expensive to be sure, but compared to what people manage to spend on boating, cars, even golfing, it can be fairly reasonable. And it's really a unique experience, if you love it there's nothing like it.

Hi Tildes!
I'm a college student considering adding a gas motor onto my existing bike. I'm in a pretty hilly city, so biking around for groceries is kinda annoying... plus I wanna just zoom around some trails in my free time.
Currently, I'm looking at one of the 49cc 4 stroke engine kits all over Amazon/Ebay, since I heard that 4 stroke motors are supposedly quieter and more reliable than 2 strokes. I don't care about speed... in fact, I don't want to be going over 30mph on a bike. 49cc also makes this thing street legal in my state.
I did consider doing an e-bike conversion as well, but those are much more expensive... a 4 stroke kit is ~$160, while any reputable e-bike battery alone is more than that. These things don't burn much gasoline either, getting 100-150 mpg! I'd have to ride thousands of miles before the fuel cost exceeds an e-bike battery.
So, any advice would be appreciated! Also, I'd be willing to spend ~300 on this if there is a compelling reason to get a better motor than the generic Ebay one. If you have motor suggestions, please link them!
Thanks,
purpuraRana

As a railfan and a graphic designer, the first thing I check out when in a new town with public transit is their transit map. You can tell a lot about a city by how they represent themselves on a transit map, and I myself have designed more maps than I can count. What's the map of your city look like? Do you have a personal favourite you think is really unknown? Any maps that you just want to rant about because of how terrible it is?

My personal favourite transit map is Constantine Konovalov's Paris Metro Map, I just love how effortlessly it weaves the lines throughout the Peripherique, and how it's not afraid to break its own established rules on angles and circles. Honorable mentions go to the London Tube and Rail map (an absolute classic), and the Mexico City Metro, which assigns a unique symbol to every station for the benefit of passengers who can't read or write.

Also, designers, feel free to share your transit diagrams! I miss r/transitdiagrams a lot and would love to see your work, fictional, redesign or otherwise!

If everything had worked perfectly, it still would have been a bum airplane." - Charles Wilson, Secretary of Defense

Back in the 1950s and 1960s, the United States attempted to design nuclear powered aircraft. This was part of a larger "nuclear craze" in the era where everything and anything was proposed to have nuclear technology applied to it. This led to all kinds of things like the Chrysler TV-8 and "peaceful" earthmoving construction projects. The only place where nuclear power or propulsion really took off was for large ocean going ships both for military navies as well as civilian tankers, cargo ships and icebreakers. Spacecraft technology was the only other "success story."

Nuclear powered aircraft, while more realistic than say nuclear cars, never quite caught on except for a few experimental engines and just one actual working aircraft. The most extensive efforts towards this during the Aircraft Nuclear Propulsion (ANP) program were the HTRE-2 and HTRE-3 experimental nuclear reactors with heat transfer assemblies designed for nuclear powered aircraft at the Idaho National Laboratory. Rather than burning fuel, the jet turbine would use the heat from the nuclear reaction to heat air sent through a compressor which would then be expelled as exhaust for thrust.

On of the more fascinating tests were the test flights of the NB-36H which while conventionally powered, flew while carrying a working nuclear reactor to test the protective shielding of the crew. It carried an air-cooled 1 megawatt reactor. The engineers and crew worked within a specially shielded nose cabin with 12-inch-thick lead-glass windows.

The project was canceled by the Kennedy administration a few months after taking office in 1961 citing high costs, poor management, and little progress towards a flight ready reactor saying:

At the time of termination, the Aircraft Nuclear Propulsion Program was still in the research and development stage, with primary emphasis on high performance reactors. Although a number of research and development achievements can be credited to this program, at the time of termination an airplane had never been flown on nuclear power nor had a prototype airplane been built. - Joseph Campbell, Comptroller General

and

Nearly 15 years and about $1 billion have been devoted to the attempted development of a nuclear-powered aircraft; but the possibility of achieving a militarily useful aircraft in the foreseeable future is still very remote. - John F. Kennedy, POTUS

Footnote: This post is a rework of a reddit post I made here a couple years back. It's not really meant to be a coherent or lengthy article but has some links and thoughts which I found interesting.