Revolutionizing Aviation: Faster Takeoff and Landing Technology Explained

[physior]

but this thread is about the future of airflight technology
and I strongly believe that we will see such technology
maybe flying saucepans? who knows

 

[Travis_King]

I doubt it. It's not economical and it makes very little engineering sense. The Harrier jet has this capability, but it's used for a specific purpose during combat missions. VTOL is expensive in fuel and weight, and really doesn't help anything regarding air traffic congestion, so I really don't see where it would be beneficial.

 

[physior]

I doubt it. It's not economical and it makes very little engineering sense. The Harrier jet has this capability, but it's used for a specific purpose during combat missions. VTOL is expensive in fuel and weight, and really doesn't help anything regarding air traffic congestion, so I really don't see where it would be beneficial.

I cannot comment on fuel or weight
but I cannot understand how you cannot see the benefit for air congestion
to be fair, I am not talking about congestion in air, but when landing and taking off only

 

[Ryan_m_b]

I understand what you say
the problem is that some times, and I am saying that this is a good time, we must not act with goal the profit, but the benefit of the society

Of course the pursuit of economic profit is not something we do all the time. Often we do things that have value beyond money. This isn't one of those cases though, here we're discussing if there are any advantages to VTOL planes.

You yourself have complained about the price of tickets. How would you feel if airliners replaced all their current jets with more expensive VTOLs and had to double, triple or even increase by 10x the price of their tickets? No airliner can run at a loss.

and don't tell me that it doesn't work like that
how many times government or companies have spent money to do research or technology?
war aircrafts is a good example, I think maybe that technology (VTO) already exists there!

The military is vastly different but they still have to consider their ROI. It's just in that case the return they are looking for is the best weapon/logistics. In terms of government spending: let's say the government announced they were going to create their own airline, that would be cheap (like public transport), not overly concerned with making a profit and paid with taxpayers money. Would you, as a taxpayer, prefer they spent that money on a cool but inefficient VTOL fleet or an standard but efficient fleet of normal jets?

 

[Ryan_m_b]

I cannot comment on fuel or weight
but I cannot understand how you cannot see the benefit for air congestion
to be fair, I am not talking about congestion in air, but when landing and taking off only

It's not that people can't see the benefit, it's the idea that the very minor saving in time would be worth the much larger expense of VTOL jets. Which have never been built anywhere near the size of a passenger jet (there are some tiltwings but they are slower and have a lower range than jets). Think of it this way: in a normal jet once it's ready to go it spends on average 10 minutes (in my experience) taxiing to the runway and taking off. Occasionally it takes longer if there is a problem but that's not too common in my experience. I've tried to find if there's any data on average times between planes being ready and taking off but didn't manage to, as this is key to your argument physior why don't you try to look for this? In a hypothetical VTOL jet the only difference is that the jet would take off once it is ready. So the total saving is on the order of 20 minutes, maybe a bit longer on flights that commonly are put into holding patterns whilst they wait for a runway (again it would be useful to have some numbers on this).

Given that do you really think that the expense of developing and introducing, what are likely to be much more expensive, VTOL jets is worth it just for an average saving of 20 minutes?

 

[boneh3ad]

VTOL systems expend considerably more fuel than their standard take-off counterparts in order to take off vertically. It is both more expensive and more environmentally damaging to try and do something like VTOL commercial aircraft. It makes no sense to pursue such an endeavor. The only reason that militaries use VTOL systems is because they have specialized requirements where their aircraft may need to land where no runway exists and/or at makeshift airfields.

The future of aviation is in more efficient designs. Eventually we will likely see something like a blended wing body. With a little bit more research we may see a return to supersonic jetliners as well, but only after we perfect the mitigation of the sonic boom so that they can be certified over land. If they are transoceanic-only aircraft, they will fail for economic reasons just like the Concorde.

 

[Doug Huffman]

Nuisance abatement, costs and safety are preeminent considerations.

And we have come full circle.

 

[Ryan_m_b]

With a little bit more research we may see a return to supersonic jetliners as well, but only after we perfect the mitigation of the sonic boom so that they can be certified over land. If they are transoceanic-only aircraft, they will fail for economic reasons just like the Concorde.

This probably deserves its own thread but I find this a very interesting topic. As it stands I'm not convinced a return to super-sonic commercial flight will occur, other than perhaps toys for wealthy people (supersonic bizjets). As I understand it supersonic flight uses up a lot more fuel per mile than subsonic, necessitating increased ticket prices. Given competition with services like subsonic first class and private jets, as well as telecoms technology obliviating much of the need to send business people quickly round the world, is there a market for a supersonic passenger jet? I've read many articles reporting that speed is a low concern for passengers over comfort and price. I wonder how many people would be willing to pay five times as much (using Concorde as an example) for a ticket for a journey only half as long. Especially given that the same price would get them a luxury seat on subsonic with money to spare.

 

[russ_watters]

Airlines seem to have been working overtime to drive passengers away in recent years. More fees, especially on checked baggage, crowded cabins, fewer, if any, amenities during flights, etc.

People used to complain about airline food; on many flights, you're lucky if you get a bag of peanuts.

Yes, I suppose right now the "something's got to give" is prices. Basic supply and demand says that when demand rises, suppliers have two choices:
1. Increase prices.
2. Increase supply.

Airlines are opting for #1, to drive down (keep from increasing) demand.

 

[boneh3ad]

This probably deserves its own thread but I find this a very interesting topic. As it stands I'm not convinced a return to super-sonic commercial flight will occur, other than perhaps toys for wealthy people (supersonic bizjets). As I understand it supersonic flight uses up a lot more fuel per mile than subsonic, necessitating increased ticket prices. Given competition with services like subsonic first class and private jets, as well as telecoms technology obliviating much of the need to send business people quickly round the world, is there a market for a supersonic passenger jet? I've read many articles reporting that speed is a low concern for passengers over comfort and price. I wonder how many people would be willing to pay five times as much (using Concorde as an example) for a ticket for a journey only half as long. Especially given that the same price would get them a luxury seat on subsonic with money to spare.

Well, yes and no. Sure, the first foray back into supersonic transports will be on the bizjet side of things, and a few companies are working on that now (e.g. Aerion has a relatively mature supersonic business jet concept and Gulfstream has one proposed). The problem is that the aerodynamics change so substantially between subsonic and supersonic flight that what functions as an efficient design in one regime typically doesn't in the other. I don't know what Gulfstream has planned, but Aerion is planning to mitigate this problem at least somewhat by designing the jet for supersonic cruise and incorporating the concept of natural laminar flow on the wings in order to help mitigate the penalties at subsonic velocities. That's probably the most likely initial approach.

NASA and AFRL also have a lot of work ongoing and externally funded with morphing structures. The initial application would be seamless control surfaces, e.g. flaps that don't have any hinges or gaps and operate by the actual trailing edge of the wing bending smoothly downward. Ultimately, though, you might imagine there would be the ability to morph the airfoil profile such that it performs well at multiple Mach number ranges.

Still, it won't be very economical or impactful on the general public unless they can get such an aircraft certified over land as well. Mitigating sonic booms for this purpose is another active area of research. I know Lockheed and Boeing have both had at various points programs for this kind of development. I don't know a whole lot about them, though.

Either way, I think eventually will will probably find our way back into the realm of supersonic transport aircraft provided we don't develop anything else superior first.

 

[Ryan_m_b]

So essentially it's a no-go on efficiency without some very big advances in materials science and noise reduction? Do you have any links on these morphing materials? Sounds interesting, if quite far off.

 

[boneh3ad]

So essentially it's a no-go on efficiency without some very big advances in materials science and noise reduction? Do you have any links on these morphing materials? Sounds interesting, if quite far off.

It's not as far off as you might thing, at least in terms of replacing flaps with flexible structures. I am sure it will be a while before we see it on any commercial aircraft, of course, but UAVs and then military aircraft may use the technology within a generation or two. I think these two videos show what is really the current state of the art, though I am not really sure. This isn't my area of expertise. As you'll see from the video, the current approach is to use elastic materials of some sort to allow the morphing. I think ultimately the goal is to move toward shape memory alloys, but I may have imagined that.





Interestingly, I just found this page at NASA that talks about a few of the things I mentioned previously as the future of aviation. In particular, note that they predict that planes will get smaller and more efficient, not larger, especially for the commuter type flights. Ultimately, if you want to reduce congestion, you end up using smaller, more efficient planes that can use an array of smaller airports. Then travelers aren't all trying to fly in and out of the same few airports.

For larger planes, the future is likely the blended wing body. It is substantially more efficient while holding more people. We could do that now, but the problem is they don't fit at traditional airport gates. Most likely, we will have to wait to see those until the military adopts them for cargo transport and forces infrastructure to slowly adapt. Until then, even if Boeing built one, no airline would buy it since there is no infrastructure for them.

http://www.nasa.gov/audience/foreducators/9-12/features/F_Can_You_Imagine.html

 

[SteamKing]

I think that unless the new technology for SSTs includes significant fuel economy improvements, it will all remain a pipe dream, whether the SST is for general commercial aviation or the specialized bizjet market.

Aircraft like the Concorde and the Boeing 2707 were designed in a era where the price of fuel was less than US $0.50 / gal and remained stable in price. Currently, when Jet A is selling for about US1.50 a gallon (and was almost US$3.00/gal six months ago), the economics of SSTs are now wholly different. It might be profitable to fly supersonic today, but six months from now, who knows? Airlines would be justifiably wary about taking a big jump into the unknown like that. Also, the pool of pilots with significant experience flying supersonic must be quite limited, more so than pilots with subsonic jet experience.

 

[boneh3ad]

That was my point about morphing wings and NLF. Technologies such as those could help push the cost of flying supersonic more into the same realm as conventional jetliners. We shall see, I suppose. Who knows, maybe someone will develop a Star Trek teleporter next year.

 

[SteamKing]

That was my point about morphing wings and NLF. Technologies such as those could help push the cost of flying supersonic more into the same realm as conventional jetliners. We shall see, I suppose. Who knows, maybe someone will develop a Star Trek teleporter next year.

A transporter might be cheaper to use than morphing materials.

 

[boneh3ad]

A transporter might be cheaper to use than morphing materials.

I might be inclined to agree with you except for the the fact that we now know that NASA and AFRL are pretty far along on the first generation of such materials and wings. If they've gotten it to the point of actually testing it on a business jet type airplane, then it's not just a pipe dream. A couple of years ago I might have chuckled at the idea, though.

 

[.Scott]

Also, I wonder why the plane couldn't just fly faster after taking off and before landing. Can't the human sustain such accelerations and velocities?

It's not clear what you mean by "fly faster after taking off and before landing". The cruise speed is a matter of fuel economy and avoiding any sonic boom.
If you mean accelerating and decelerating to cruise speed, there are other factors. Immediately after rotation, the jet will accelerate to some airspeed below either 200 KTS or 250 KTS depending on whether the airport is in Class B or Class C airspace (http://ww1.jeppesen.com/download/aopa/jul-aopa.pdf). At that point, the pilots primary objective is to rapidly gain altitude - so he will pitch up enough to keep to his chosen speed with maximum or near-maximum thrust.

The deceleration is also limited by the class of airspace - but more importantly by the design of the aircraft. There are a series of aircraft reconfigurations that occur once the airplane is on final approach - changes to flaps, slats, landing gear, and/or air brakes. When the jet is configured for cruise flight, it will be fuel efficient at fairly high altitudes. However, it cannot make a normal landing in that configuration because it needs to maintain too high a speed for contact with the runway. The landing configuration occurs in stages with the aircraft reconfiguring as the airspeed is reduced - all the way until touchdown.

Obviously, it is possible to accelerate and decelerate faster. Takeoffs and landing on an aircraft carrier are the best examples. And some those aircraft are capable of supersonic flight. But the economics in protecting a Naval fleet are different from commercial air transport.

The airspeed restrictions for class B and C airspace are set for two reasons: aircraft maneuvering distances and how long it takes for air traffic control to to communicate with and effectively redirect aircraft.

 

[montoyas7940]

I noticed that a significant part of the whole travel time is taken by the take off and landing.

My experience has shown parking, check-in, security/TSA, baggage handling, rental cars and delays or cancellations to be the inefficiencies of commercial airline travel.

My prediction for the future is small pilotless aircraft with point to point travel into tiny airports.

 

[physior]

My experience has shown parking, check-in, security/TSA, baggage handling, rental cars and delays or cancellations to be the inefficiencies of commercial airline travel.

My prediction for the future is small pilotless aircraft with point to point travel into tiny airports.

with same accelerations/deccelerations as todays aircrafts? with the same take off and landing methods as todays aircrafts?

 

[montoyas7940]

Keep in mind predictions of the future are usually wrong...

ATC speed limits would probably be relaxed with the advent of more automation and high speeds could be carried into the approach. Also the approaches could be greatly abbreviated since there would be little or no human involvement. Basically drop in like a rock and throw out some high drag devices for a short landing. A stabilized approach for safety would be pointless.

The VTOL efficiency issues might be solved, but much later I would imagine. The aircraft could drop into an air cushion generated by equipment installed on the ground.

For takeoff IDK, an aircraft carrier on land? Maybe.

 

[Ryan_m_b]

My prediction for the future is small pilotless aircraft with point to point travel into tiny airports.

What are you basing this on? The economics of flight would seem to favour fewer larger aircraft over more numerous smaller ones.

ATC speed limits would probably be relaxed with the advent of more automation and high speeds could be carried into the approach. Also the approaches could be greatly abbreviated since there would be little or no human involvement. Basically drop in like a rock and throw out some high drag devices for a short landing. A stabilized approach for safety would be pointless.

The speed that modern jets travel at are more to do with fuel efficiency than regulation. As for rapid, short landings this sounds like it would put considerable strain on the passengers and vehicle. What is the justification for this?

The VTOL efficiency issues might be solved, but much later I would imagine. The aircraft could drop into an air cushion generated by equipment installed on the ground.

For takeoff IDK, an aircraft carrier on land? Maybe.

Is there any research you could point to that suggest that these would be both possible and commercially viable? Have there ever been pilot studies? It seems that you throwing out ideas at random on that basis that they sound futuristic. If so I'd like to remind you, and all members, that all claims should be backed up with good evidence and reasoned argument. Otherwise the thread will just be locked.

 

[Doug Huffman]

Keep in mind predictions of the future are usually wrong... [ ... ]For takeoff IDK, an aircraft carrier on land? Maybe.

Catapults require huge power. While CVN reactor plant sizes were still catching up, anecdotally the operators would anticipate launch operations with higher stored heat and power. The stresses on the AC are significant and require special construction considerations.

 

[mfb]

Catapults are also unpleasant, and the launches still require very powerful engines on the airplanes.
Really small (and many) airports won't happen with the current length requirements of runways, however.

For long distances, I don't see changes in the near future. For short distances, you have trains, buses and cars as option.

 

[montoyas7940]

What are you basing this on? The economics of flight would seem to favour fewer larger aircraft over more numerous smaller ones.

People are often willing to pay for convenience. Business jets operating from smaller airports being the proof. Also single pilot IFR operations are now possible/legal in some small jets due to cockpit automation.
FAR 135
http://virtualskies.arc.nasa.gov/navigation/9.html

The speed that modern jets travel at are more to do with fuel efficiency than regulation..

Speed limits at cruise and other than cruise are regulated. FAR 91.117. OP originally addressed the inefficiency of the takeoff and landing phase of flight.

As for rapid, short landings this sounds like it would put considerable strain on the passengers and vehicle. What is the justification for this?.

Sounds like? Considerable? I'm not sure what you are asking here. How rapid and how much strain needs justification? Reductio ad absurdum?

Is there any research you could point to that suggest that these would be both possible and commercially viable? Have there ever been pilot studies? It seems that you throwing out ideas at random on that basis that they sound futuristic. If so I'd like to remind you, and all members, that all claims should be backed up with good evidence and reasoned argument. Otherwise the thread will just be locked.

Everything I mentioned is either existing technology or an extension of existing technology. Whether something is commercially viable is up to the consumer.

 

[montoyas7940]

The VTOL efficiency issues might be solved, but much later I would imagine. The aircraft could drop into an air cushion generated by equipment installed on the ground.

For takeoff IDK, an aircraft carrier on land? Maybe.

I'll admit this is quite a stretch.

 

[mfb]

People are often willing to pay for convenience. Business jets operating from smaller airports being the proof.

The fraction of the population that wants to afford business jets is very small.

Speed limits at cruise and other than cruise are regulated. FAR 91.117. OP originally addressed the inefficiency of the takeoff and landing phase of flight.

Yes they are regulated, to the speeds the airlines consider as convenient, taking safety and the environment into account of course. Without regulations, airplanes would not suddenly fly faster as this would be very inefficient, dangerous or simply impossible. They would just have more chaos in their speed distribution.

How rapid and how much strain needs justification?

Rapid accelerations are unpleasant for both passengers and machines.

Everything I mentioned is either existing technology or an extension of existing technology.

That is true for many things that do not exist because they are way too expensive.

 

[anorlunda]

I think the future of air travel will be greatly influenced by pressure on people to reduce their fossil fuel footprint.

I live frugally. A single airplane leg of 300 miles once a year would double my footprint.

Rumor has it that environmentalists will make meat versus veggies a big issue this year. Air travel is roughly at the same level of wastefulness.

I'm not talking about flying versus alternative transportation means, I mean abstaining from business or pleasure travel. Ditto for driving to the store as compared to package delivery.

 

[montoyas7940]

The fraction of the population that wants to afford business jets is very small.

No. But the number of people willing to fly out of smaller airports on smaller airliners is not small. And in some cases it is not the consumer who pays. http://www.dot.gov/policy/aviation-policy/small-community-rural-air-service/essential-air-service
Pilot pay is shrinking at regional airlines and the reality is public perception and regulation is the only reason airlines continue to need/pay pilots. The technology exists and is cost effective to eliminate the (or one of the) pilots. While pilot pay is a small portion of the cost it is a portion. Also a look at accident statistics will show that eliminating the pilot (and pilot error) should improve safety and associated costs. Here is a good website for info http://www.planecrashinfo.com/cause.htm

The point I tried to make was there will be more operations by smaller aircraft into smaller airports providing more point to point service. And those operations will be conducted with increasingly advanced aircraft which could fly without pilots. I can see I didn't do it well.

Yes they are regulated, to the speeds the airlines consider as convenient, taking safety and the environment into account of course.

Did you read 91.117? Convenience and environment is not mentioned. http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&sid=3efaad1b0a259d4e48f1150a34d1aa77&rgn=div5&view=text&node=14:2.0.1.3.10&idno=14#se14.2.91_1117

The safety mentioned is mainly due to ATC and their ability to route aircraft into and out of busy airspace as well as safely separate VFR and IFR aircraft. This is why the speeds are different for different airspace.

Noise abatement can also be complied with by the use of smaller airports in lower density areas and smaller aircraft. I agree, not the fuel efficient solution. But noise abatement policy doesn't mention aircraft efficiency (and only briefly operational efficiency). https://www.faa.gov/about/office_or...oise_emissions/airport_aircraft_noise_issues/

Without regulations, airplanes would not suddenly fly faster as this would be very inefficient, dangerous or simply impossible.

Staying high longer is more efficient. The extended operation at lower altitudes to accommodate an outdated ATC system is not. But staying higher and fast means there is more energy to dissipate and less time to do it. Pilots often get called out by ATC for busting speed limits, usually it is a gentle "aircraft XXX say speed" followed by a sheepish "ummm 250 Kts." as the pilot quickly slows the aircraft to 250 kts. The reality is human pilots need the added response time to stabilize the decent and approach. And ATC needs time to route and sequence traffic safely. However as time goes on less and less of the landing is flown by the airline pilots. Automation can be and often is used all the way to the ground. Because it is safer and would be even with a higher and steeper approach. The technology exists. Regulation and procedures will eventually catch up.

They would just have more chaos in their speed distribution.

True. But ATC already routes aircraft from as slow as or slower than 50kts to as fast as 250kts for takeoff and landing. An automated aircraft is more predictable and precise.

Rapid accelerations are unpleasant for both passengers and machines..

Also true but the current system of gradual reduce power, letdown, level, slow, add power, repeat of the aircraft for separation and sequencing has much room for improvement. One smooth higher speed decent would be more comfortable and there is no reason a higher rate of acceleration would even be neccesary as the rate could be continuous with no level off or holds. As an added benefit the steeper angle would simplify noise abatement because the engines would be at lower power longer and the footprint of the approach would be smaller.

Take a few minutes and watch traffic. You can click individual flights and watch altitude and airspeed. I think you will see what I mean by room for much improvement.
http://flightaware.com/live/airport/KATL
Imagine if each flight could depart and arrive "on course".
Take a look at TCAS and consider the possibilities with further integration. http://en.wikipedia.org/wiki/Traffic_collision_avoidance_system

Just to clarify, by high drag device I didn't mean a parachute. I meant spoilers and speedbrakes.

That is true for many things that do not exist because they are way too expensive.

Currently I can't board a 19 seat pilotless aircraft from a small airport near my home and land with a steep expeditious decent at a small airport near Disneyworld. Pilotless aircraft do exist and small convenient airports do exist. Steep expeditious approaches are possible and even performed on occasion.
But this is not a case of don't exist. This is a case of not being used. Mostly because of regulation and public perception.
Except for the land based carrier takeoff or air cushion landing of course. I agree those would be expensive and are as yet completely unnecessary and impractical.

 

[mfb]

No. But the number of people willing to fly out of smaller airports on smaller airliners is not small. And in some cases it is not the consumer who pays. http://www.dot.gov/policy/aviation-policy/small-community-rural-air-service/essential-air-service

It is always someone who pays.

Did you read 91.117? Convenience and environment is not mentioned. http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&sid=3efaad1b0a259d4e48f1150a34d1aa77&rgn=div5&view=text&node=14:2.0.1.3.10&idno=14#se14.2.91_1117

Where is your point? Do you really think the lack of supersonic passenger aircrafts or very fast very small planes comes from regulations?
Also, the US is not the whole world.

Noise abatement can also be complied with by the use of smaller airports in lower density areas and smaller aircraft.

Who wants to start in low density areas? Long-distance flights (where the airport location is less important) will need fast airplanes, and that means large airplanes and runways. And for short-distance flights, the airports in the middle of nowhere look less attractive.

Staying high longer is more efficient. The extended operation at lower altitudes to accommodate an outdated ATC system is not. But staying higher and fast means there is more energy to dissipate and less time to do it. Pilots often get called out by ATC for busting speed limits, usually it is a gentle "aircraft XXX say speed" followed by a sheepish "ummm 250 Kts." as the pilot quickly slows the aircraft to 250 kts. The reality is human pilots need the added response time to stabilize the decent and approach. And ATC needs time to route and sequence traffic safely. However as time goes on less and less of the landing is flown by the airline pilots. Automation can be and often is used all the way to the ground. Because it is safer and would be even with a higher and steeper approach. The technology exists. Regulation and procedures will eventually catch up.

I agree.

An automated aircraft is more predictable and precise.

It would also be more regulation (from an automatic system this time).

Also true but the current system of gradual reduce power, letdown, level, slow, add power, repeat of the aircraft for separation and sequencing has much room for improvement. One smooth higher speed decent would be more comfortable and there is no reason a higher rate of acceleration would even be neccesary as the rate could be continuous with no level off or holds.

I was referring to the idea of shorter runways here. If you want shorter runways, accelerations have to increase.

As an added benefit the steeper angle would simplify noise abatement because the engines would be at lower power longer

Only for descent.

I think you will see what I mean by room for much improvement.

No one disagrees with that. And free flight or something similar will come.

 

[montoyas7940]

My experience has shown parking, check-in, security/TSA, baggage handling, rental cars and delays or cancellations to be the inefficiencies of commercial airline travel.

My prediction for the future is small pilotless aircraft with point to point travel into tiny airports.

It is always someone who pays.

True. But the point is someone is paying for it. It happens. And many small operations are profitable without government subsidy.

Where is your point? Do you really think the lack of supersonic passenger aircrafts or very fast very small planes comes from regulations?
Also, the US is not the whole world.

I think you have my post confused with someone elses. While supersonic flight over land is regulated, I never mentioned faster aircraft as a means to improved effeciency. You are correct, the U.S. is not the whole world. But the ICAO gets most of it. U.S. airspace designations have been changed to conform to ICAO standards (for the most part). The 250kt rule is pretty common world wide, enough for a reasonable discussion -I hope. FAR 91.817-821 covers supersonic flight restrictions over the U.S. by the way. And yes, ICAO has similar rules.

Who wants to start in low density areas? Long-distance flights (where the airport location is less important) will need fast airplanes, and that means large airplanes and runways. And for short-distance flights, the airports in the middle of nowhere look less attractive.

People who live in low density areas want to start in low density areas and people going to low density areas want to end in low density areas. But maybe we do need to agree on "low density". I wasn't speaking of the middle of nowhere. Consider KPDK airport as an example. It is near Atlanta and certainly convenient to many people but at the same time much less dense than KATL. There are many other similar airports around ATL.
The current spoke and hub system brings small and medium sized aircraft from smaller airports in lesser density areas into large airports in greater density areas. Some people and baggage are shuffled onto large aircraft for long distance flights into other greater density areas. Some people however get right back on other small and medium aircraft for a flight to lesser density areas. The benefit of point to point is in allowing some, or even most, to skip the hub and fly direct from small airport to small airport on an even smaller plane than the planes used in spoke and hub. Less traffic through the hub expedites operations there as well.

It would also be more regulation (from an automatic system this time).

So true! What do we have to do to get less regulation?

I was referring to the idea of shorter runways here. If you want shorter runways, accelerations have to increase.

True if landing speed stays the same. But lighter aircraft generally land slower so extra airspeed carried into the descent can be bled off in the air on final (quietly at low power).

Only for descent.

Watch the flights out of KATL and I think you'll realize how much more time is spent in descent to approach and landing than is spent in takeoff and climbout.

No one disagrees with that. And free flight or something similar will come.

I am more excited about self driving cars! Flying (not on an airline) is fun, driving sucks.