[limitedfrom]

50% seems very unreasonable here, if not in the wrong direction overall.

Ikarus C42 at about 86 knots will use 13 L/hr, for a two-hour flight, it's 26 L fuel and 8.31 kg CO2/gal avgas[1], this comes to 57 kg CO2 to cover 320 km (and this is assuming it immediately starts covering flight distance and not using gas for climbing/approach, etc.).

An average new car in the EU uses 6 L/100 km in 2019[2]. To drive 320 km, this comes to 19 L of gasoline (8.1kg CO2/gallon finished motor gasoline[1]), which is then 41 kg CO2.

Even if you had to make the auto trip 400 km because roads aren't as direct, this comes to 51 kg CO2.

Nevermind that airports are rarely your final destination, nor in the city centre like train station would be, which adds significant distance to your overall trip.

[1] https://www.eia.gov/environment/emissions/co2_vol_mass.php [2] https://www.iea.org/articles/fuel-economy-in-the-european-un...

[creshal]

> Even if you had to make the auto trip 400 km because roads aren't as direct, this comes to 51 kg CO2.

What if there's a sogging great mountain range in the middle and I literally do need to drive 2-3x as far, because (rail) tunnels take something between 2 and 3 decades to build and won't be finished before 2040, if any are even planned to begin with?

[limitedfrom]

You can always cherrypick examples that favour planes. In fact, to take it to the extreme, you can just put bodies of water in between and that might become practically the only choice as distances increase (e.g. there are no ferry service between Honolulu and Kona in Hawaii), and I'd agree with you in some cases planes are the most reasonable way to go between places.

That said, looking at the website for the main post, I don't think that's the main use case it has in mind: top banner rotating between "Flying made easy for first-time aviators/weekend trips/avoiding traffic" or "We believe the freedom of flying is an unparalleled experience that everyone deserves access to" and "The power of flight is intoxicating".

It's great if existing use cases of GA aircrafts have sleeker/more intuitive interfaces, but adding demand in this area (more hobbyists, more rich people using it for shuttling/avoiding traffic, encouraging people to live in very remote areas, etc.) and using it as transportation-mode will unlikely ever become environmentally reasonable.

[creshal]

Even a million additional GA airplanes used for leisure trips won't ruin the environment as much as cryprocurrency and AI does, so I'm not sure why HN of all places suddenly discovers their concern for environmental sustainability.

[AdrianB1]

That's exactly the case. Driving from Bucharest to Vatra Dornei, Romania. No highway yet, the one in construction (A7) is still going around the Carpathian mountains for 370km, it will make the drive faster but not shorter. Also driving highway speed takes more gas.

[limitedfrom]

Then argue for convenience/speed/fun as I write here[1], not in the conversation about fuel usage. Even your example, driving from Bucharest to Vatra Dornei, RO is 490 km (DN12; 1.41x) or 520 km (DN2; 1.5x) vs 347 km, hardly 2-3x the parent comment you're responding to, again keeping in mind that the airport won't be in the middle of the city.

As for highway speeds, cars are calibrated to have the highest efficiency at highway speeds[2][3], so per distance, most cars will do best at reasonable highway speeds.

[1] https://news.ycombinator.com/item?id=41166749 [2] https://www.researchgate.net/figure/Speed-fuel-consumption-c... [3] https://qph.cf2.quoracdn.net/main-qimg-2ddbd8f31c84cefba540d...

[yunohn]

> driving highway speed takes more gas

Hmmm, in my experience, highway speeds are conducive to ICE efficiency and use less gas than city traffic stop and go results in. It also disperses pollution outside the areas people work/reside in.

[creshal]

There's three speed categories as far as the EU is concerned:

- highway

- not highway, not city

- city

The 90-110km/h limits of regular roads tends to hit the sweet spot of engines more reliably than the 130+ of highways, a lot of smaller European car engines are uncomfortably close to redlining at 130+, especially older ones.

[sdeframond]

Air resistance is not linear, which makes it difficult to be more efficient at higher speed, even if the engine is tuned for this.

In my personal experience with both my current and previous cars, the sweet spot is constant speed about 65 to 80kph.

It does feel slow though.