41

From the B-29's commander training manual, page 69: The range loss at high altitudes is caused almost entirely by the rich mixtures required at high powers and the larger cowl flap openings needed to cool the engines at high altitudes. In general, there is no loss in range up to 15,000 feet and the range losses at higher altitudes occur almost entirely ...


29

I'm going to simplify and assume that jets and cars burn the same fuel, and output the same exhaust, CO2, NOx and all. I'm going to compare only short-haul flights against cars. According to Wikipedia, an A-320-NEO does 1.95L/100km per seat. Assuming flying at 80% capacity, that gives us 2.4L/100km per seat. According to The Car Guide, a 2019 Honda Civic ...


27

The only reason for your flight to operate at such low altitude is because it is cheaper for them to do so. As you said it is due to weather, other route/altitude may not be available. They can cancel the flight but that is likely to be costly. They may have to find accomodation for you and crew until they can put you to the next flight. Sub-optimal flight ...


26

I used the playback function of Flightradar24 for the 18th at 23:00 UTC, and the amount of traffic above 10,000' (filtering by altitude) seemed very normal compared to other days. I'm baffled as to why they flew so low, but I can address your fuel question in some detail. The difference in fuel consumption is ~693 kg of fuel, and would cost an extra ~$415, ...


24

Here are some options for flying in an environmentally friendly way: Use an electric trainer: Since last year the all electric trainer aircraft Pipistrel Alpha Electro has FAA certification. Assuming the batteries are charged with renewable energy, this would mean no greenhouse gas emissions at all (excluding manufacturing). It will probably still take some ...


19

Way to go on thinking outside of the box. Actually, it might work. Although the logistics of it are above my pay-grade. Maybe, some smart group out there could make it work. But, your question doesn’t ask for ways to make it works. It specifically asked for reasons it might not works. So, here it goes: cable car feasibility over all does not have a great ...


16

It was because they could get there faster on a "TEC route." IFR flights are subject to congestion management at the ARTCC level, which means they have to wait their turn in line to be allowed into the airspace. That used to be done with holds (and still is in many other countries), but the US will slow down aircraft, reroute them or even delay takeoff to ...


16

tl;dr: L/D of the airframe and specific fuel consumption of the engines are credible but that doesn't add up to the claims made regarding fuel consumption and speed relative to jets. Laminar flow seems to be used as the snake oil to sell this to gullible customers. The fuselage shape is inspired by a laminar flow airfoil, like the NACA 64-021 shown below, ...


15

By using as much simulator time as possible.


13

It depends on what you mean by "environmentally friendly." Just for an example, let's consider a 1000 mile trip. An A320 burns about 5 gallons of fuel per seat per hour, and with 150 seats this comes to 750 gallons per hour. A 1000 mile flight will take about 2.5 hours, so this comes to 12.5 gallons per seat, or 1875 gallons total. This means that 2 seats ...


11

Overall, the two very different methods of transportation have surprisingly similar amounts of emissions, so close it's tempting to oversimplify things to a statement like "planes are 20% more efficient than cars". The exact circumstances make it so you can't say one is better in many or even most circumstances. Even worse, different definitions of "...


11

Practically this would not work due to the sheer size of the cable you would need. A fully loaded A380 is 1.25 million pounds. A B787 is .5 million pounds and a B737 is about 150,000 pounds. On a busy day at a large airport you may have 20 airplanes or more in line, assuming a mix of airplanes you'd have somewhere around 5 million pounds of airplanes to tow ...


10

The 7:1 rocket figure is perhaps for the unrealized single-stage-to-orbit, getting a payload to low Earth orbit (LEO) is closer to 9:1, and going to the moon and back is 23:1 (Saturn V). If a soda can's content is the fuel, then the rocket stages that are jettisoned have better fuel to empty mass ratio compared to that soda can, so staging is not the main ...


9

While not specific to an A320, nor a make/model of automobile, these averages may help put your question into perspective. How any of it relates to "environmentally friendly" is purely subjective. "...the average fuel consumption in 2017 was 34 pax-km per L (2.94 L/100 km [80 mpg‑US] per passenger)..." from https://en.wikipedia.org/wiki/...


9

I am basing the following calculations on the excellent answer by Peter Kämpf to this question: How much of an improvement would a 1% weight decrease on an airplane be to the industry?. We can approximate the fuel usage with the Breguet equation $$ m_\mathrm{TO} = m_\mathrm{Landing} \cdot \exp \left( \frac{R \cdot g \cdot b_f}{v \cdot L/D} \right) , $$ ...


9

The following table shows the long range cruise control data for a Boeing 737-800 (source: FCOMv1 Performance Inflight - All Engine PI.31.2): Let us consider a typical cruise at FL370 with a weight of $ 65 \, \mathrm{t} $. The table tells us that the fuel flow per engine would be: $$ \mathrm{FF} = 1231 \, \mathrm{kg}/\mathrm{h} $$ We are interested in the ...


8

Learnt to fly a solar powered hot air balloon The UK's International Balloon Fiesta in Bristol is a celebration of all things hot air ballooning, but this year it's taken a big stride into the future. August 6th saw the maiden public flight of the world's first hybrid hot air balloon, which flies by heating regular air from the sun alone.Source In theory,...


8

This scenario isn't common but it isn't exactly rare, either. You take off with a full plane & lots of fuel for holding & an alternate, planning to arrive just at max landing weight. Then, due to shortcuts and/or better than forecast tailwinds, you under-burn & see that you'll arrive above max landing weight. First, the hypothesized rule in Part ...


7

The aircraft you flew on was D-AIUX, a Lufthansa Airbus A320-214. On 10 February it was scheduled to fly from Munich to London, but the flight was cancelled due to the storm: (flightradar24.com) If the aircraft was fueled for this flight the day before, it would need: 3.13 kg/km x 944 km = 2.95 t of fuel for the trip about 1.5 t of reserve fuel After ...


7

Both-engine-out glide performance isn't accounted for and isn't a certification requirement (of any airplane that I'm aware of). Airliners have good glide performance as a happy side effect of design optimization for cruising at high altitudes. What does have to be accounted for is single engine performance issues; things like departure performance with an ...


7

Short answer: that fuel saving figure does not depend on the stator stage.[1] The aft stator function is swirl recovery, assuming its weight penalty can be offset. GE's design GE's (part of CFM) patent for that engine was filed in 2020: Unducted thrust producing system architecture US20200308979A1. From the patent, the second set of blades are optional, and ...


6

There is an existing triple redundant hydraulic system in those planes required used for the control surfaces. Those are not something you want controlled by pneumatics. This means the weight of the compressor, buffer tank etc. is already there and using it for brakes means you only need to pull a line from a supply/return line (which would also be near the ...


6

Much like how a gas pedal controls the fuel input of a car's engine, so do the thrust levers on jet-liners. The coasting equivalent is idle thrust. The engine keeps running, but with minimal fuel flow. The minimum fuel flow is not fixed as it is a function of altitude, airspeed, and temperature. Nowadays it is typically managed by the FADEC, so the pilot (...


6

The flight crew is responsible for ensuring there is enough fuel on board before taking off. Further, they are required to check the fuel consumption en route at regular intervals to ensure there is enough fuel to continue. If fuel is consumed at a higher rate than expected, perhaps due to headwinds, the crew will divert to another airfield before the fuel ...


6

The answers by Bianfable are pretty good. I'd add one more option: Use a powered glider. There are gliders with a small engine, electric or otherwise. Some look like propeller planes with glider wings, some have a much smaller engine and a retractable or foldable propeller. My favourite example is this one. These can take off under their own power, which is ...


6

Cable cars, trains, and ski lifts essentially live their lives on the track or line. The repositioning and shuffling that must happen on an airport, especially pulling into and out of arrival/departure gates would make such limited track systems a nightmare. There would be a need for aircraft to move around under their own power or be towed by a tug, at ...


6

As far as aerodynamics is concerned, there is no jet stream1. The aircraft flies at a fixed airspeed with respect to the surrounding air2. How much thrust it needs, how much lift it experiences and so on, only depends on the airspeed w.r.t. to the surrounding air. How fast that air is moving across the ground (wind speed) is irrelevant for aerodynamics. The ...


6

Best way to conceptualize it is to just analogize it to a ship navigating ocean currents. If a ship going 15 knots through the water is riding with a current going 3 knots, it's speed over the ocean bottom is 18 knots (call it a "tail current"); if it's going into current, it's going 12 knots (call it a "head current"). If it's going at ...


5

That depends how you define longer in aviation. As you can look at it geographically or on the clock. The hard answer is no, the most fuel efficient route is the one that has the aircraft in the air for the shortest amount of time. If you can take advantage of a big tail wind 20 miles south of the geographically shortest route or at a slightly higher ...


5

TU-144 = 9.78 passenger mpg TU-144 figures found on another forum, from an official flight planning document: https://www.airliners.net/forum/viewtopic.php?t=1355819#p19483811 -- By comparison the TU-104A = 15.88 passenger mpg From an old Aviation Week story on the TU-104: http://aviationweek.com/blog/tupolev-104-harsh-proof-rapid-soviet-progress-1956 ...


Only top voted, non community-wiki answers of a minimum length are eligible