Electric flight/ Hybrid flight:

Quote: Ayecarumba

... they could provide convenient ways to avoid the time and hassle of road travel and parking at the large international hubs.

For 20 years I have been reading about making better use of smaller regional airports as opposed to simply the large hubs. The FAA had a major initiative about a decade ago leading us to expect an avalanche of small aircraft.

But last year 72.62% of passenger boardings took place at the 30 airports that the FAA dubs as LARGE (by definition a LARGE airport handles 1% or more of the national passenger load).

Quote: Pacomartin

I wonder if there is some kind of design possible that is "almost lighter than air" where you don't need the long runways or the 10MWH electric motors to propel the aircraft, but it does not have the true buoyancy of a LTA aircraft.

That would be very hard to do, when you consider a paper airplane made of rice paper is not even close to being neutrally buoyant in air.

Lighter than air craft, while needing no power for lift, are also very un-aerodynamic, which means they need much more power to overcome air resitance and drag during propulsion.

Quote:

Consider the Bohai Strait which is 123 km long. It is too short for conventional aircraft, but a ferry takes 8 hours and it is 1400 km to drive around the bay.

A tunnel is estimated to cost $34 billion.

A LTA than aircraft couldn't really carry many people and would probably be too slow.

An LTA craft could not carry your car along with you, the way ferries and trains can.

Quote: Nareed

That would be very hard to do, when you consider a paper airplane made of rice paper is not even close to being neutrally buoyant in air. Lighter than air craft, while needing no power for lift, are also very un-aerodynamic, which means they need much more power to overcome air resitance and drag during propulsion.

I realize those basic parameters. I used to work in a hypersonic wind tunnel doing mathematical models.

I am asking about a middle ground, where you have some lift that makes the vehicle much less heavy than a conventional aircraft, and still relatively un-aerodynamic but capable of enough speed to make a 300 mile trip feasible.

Quote: Nareed

An LTA craft could not carry your car along with you, the way ferries and trains can.

Obviously the heavy equipment would still have to move by ferry. But can you move people over 123 km of water and marsh at a reasonable rate that you don't need $35 billion for an underwater tunnel.


Look at Expresswest which has been planning for almost a decade to build a high speed rail from Las Vegas to Palmdale, a distant suburb of Los Angeles. Nearly everyone agrees that only a train that goes to Disneyland area will be very popular. You are talking about 200 mile distance.

Can you build something a little sleeker than a blimp that could do the distance under electric power in a reasonable amount of travel time? Obviously you won't be able to land on a runway.

Quote: Pacomartin

I realize those basic parameters. I used to work in a hypersonic wind tunnel doing mathematical models.

Cool!

Quote:

I am asking about a middle ground, where you have some lift that makes the vehicle much less heavy than a conventional aircraft, and still relatively un-aerodynamic but capable of enough speed to make a 300 mile trip feasible.

This is something I gave some thought to years ago.

To begin with you need something less dense than helium. The one thing readily available right now, no waiting is hydrogen. Yes, yes we all know about the Hindenburg, though in all likelihood what caught fire was the metallic paint on the fabric covering. Still, hydrogen leaks are very easy to ignite, even with a minor static discharge.

So what's less dense than hydrogen? Nothing readily available. Except one thing: nothing.

Literally nothing. A vacuum.

Of course, a gas, like hydrogen or helium, can be pressurized to match the outside ambient atmospheric pressure, making the stress on the container zero. Vacuum by it's very nature cannot do this. So you'd need a containing vessel strong enough to withstand one whole atmosphere of pressure differential, and that would make your craft much heavier than air.

Unless you could come up with a kind of force field to keep the vacuum empty, or to stiffen a lightweight material to form a container.

That's when I decided the idea was too far out for me.

Quote:

Obviously the heavy equipment would still have to move by ferry. But can you move people over 123 km of water and marsh at a reasonable rate that you don't need $35 billion for an underwater tunnel.

In China? It has to be a tunnel, or a ferry. Otherwise this egalitarian worker paradise would see poorer people without cars traverse the straits faster than wealthier people with cars. We can't have that.

Seikan tunnel in Japan opened in March 1988



The Seikan Tunnel is the world's longest tunnel with an undersea segment (The Channel tunnel, while shorter, has a longer undersea segment). Connecting the islands Honshu and Hokkaido by a fixed link had been considered since the Taishō period (1912–1925), but serious surveying commenced only in 1946, induced by the loss of overseas territory at the end of World War II and the need to accommodate returnees. In 1954, five ferries, including the Toya Maru, sank in the Tsugaru Strait during a typhoon, killing 1,430 passengers.

The tunnel was opened on 13 March 1988, having cost a total of ¥538.4 billion (US$3.6 billion) to construct.Once the tunnel was completed, all railway transport between Honshu and Hokkaido used it. However, for passenger transport, 90% of people use air due to the speed and cost. For example, to travel between Tokyo and Sapporo by train takes more than nine hours, with several transfers. By air, the journey is three hours and thirty minutes, including airport access times.

On 26 March 2016 (28 years after opening) Shinkansen services commence operation through the tunnel, taking speeds up to 140 mph.

The bottom line is that the tunnel hardly put a dent in the second busiest air route in the world. Tokyo to Sapporo is 819 km and has 7.8 million passengers per year.
I think the primary aircraft of choice is a Boeing 777 outfitted with 500 seats.

Quote: Pacomartin

I think the primary aircraft of choice is a Boeing 777 outfitted with 500 seats.

I probably don't really mean it, but I'd prefer 9 hours in a train.

I seriously don't think I mean it...

Well a 140 mph, I am sure the trip is now about 5-6 hours.

Anyway, most of these electric designs for aircraft are considering under 500 km, so this one is probably out of the question at 800 km

Only 3 of the top 11 busiest air routes in the world are under 500 km
1 South Korea Seoul-Gimpo South Korea Jeju 450 km
6 Brazil São Paulo Brazil Rio de Janeiro 366 km
7 Japan Tokyo Japan Osaka 405 km

2 Japan Tokyo Japan Sapporo 819 km
3 Japan Tokyo Japan Fukuoka 883 km
4 Australia Sydney Australia Melbourne 706 km
5 China Beijing China Shanghai 1075 km
8 Hong Kong Hong Kong Taiwan Taipei 780 km
9 Japan Tokyo Japan Okinawa 1554 km
10 Australia Sydney Australia Brisbane 800 km
11 South Africa Johannesburg South Africa Cape Town 1271 km

Quote: Pacomartin

A tunnel is estimated to cost $34 billion.

Why not a fleet of RORO ferries with just two iron-clad rules: No Oriental officers, No Oriental crew. Much cheaper, much faster than building a tunnel at such a high cost.

Airbus switches policy.
From AVWeb

Airbus is dropping plans to produce the electric E-Fan 2.0 and E-Fan 4.0, planned as two-seat trainer and tour-seat touring aircraft. The company had announced in 2014 that it expected to bring the E-Fan 2.0 to market in 2018 as a joint venture with Daher-Socata, the French airframe maker best known for its TBM turboprops. The new plan is to move away from pure electric propulsion and produce a hybrid-electric, regional jet-sized aircraft that would enter service over a decade from now—2030.

Zunum Aero, Kirkland, WA plans 'walk on, walk off' flying bus system using electric flights and local airports rather than regional or major airports.
Air traffic currently uses 2 percent of airports. Quiet electric planes and close-in small airports. No travel to what people now think of as "the airport".

Venture envisions Boston to Washington at half the price AND half the time by bypassing all large, well-known airports.

https://venturebeat.com/2017/04/05/how-zunum-aero-plans-to-revolutionize-air-travel-with-electric-planes-and-regional-airports/?google_editors_picks=true