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Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:01 pm
by trpmb6
https://www.bloombergquint.com/technolo ... -to-boeing

A plane that lands on a runway, shrugs its wings off, turns into a train and rolls on to rails to drop you off at your local station. That's what a French entrepreneur, who's made millions by connecting engineers with industrial groups, is pitching to Boeing Co. and others. "Link & Fly" is Akka Technologies' new flagship aircraft design, with wings that come off to hasten turnover at airports and make boarding easier and closer to passengers' homes.


It's a novel idea but in practice not very practical. I foresee the same fuselage bending and torsion issues that killed other similar projects that saw cylindrical rail cargo cars that were to be latched onto a similar wing design. You lose too much moment of inertia when you break the fuselage up like this. One look at the design from a structural standpoint tells you it's not feasible.

Still, fun concept.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:07 pm
by smithbs
Ironic that someone would propose so many billions of dollars to replace a hundred yards of walking on human legs from the jetway to the train terminal. Personally I like walking a couple hundred yards after a plane ride.

My statement assumes that there is a train terminal nearby, which in many cases there isn't. That's more of an issue of planning and economics.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:18 pm
by exFWAOONW
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:28 pm
by trpmb6
exFWAOONW wrote:
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.


Agreed. I have a unique perspective in that I've run structural analysis on both aircraft and rail cars. The concept is a total non-starter in my view for the reasons we've both pointed out. The two loading requirements are just too differing - there isn't enough overlap to make it a feasible lightweight design.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:42 pm
by LVISA
I wonder if the Pan Am 707 in the background is Plan B... :D

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:52 pm
by ExMilitaryEng
Wow, that would be an ideal project for Bombardier! They have expertise in both trains and aircrafts :silly: (and previously in watercrafts, snowmobiles, quads and motorbikes - spinned off a while ago to BRP)

Let's figure out a product that replaces them all!

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 2:57 pm
by bob75013
Well we already have Airbuses. Flying trains would be the next logical step. ;-)

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 3:17 pm
by mutu
Didn't we have a Skytrain already?

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:08 pm
by c933103
Most rail infrastructures in the world can't even fit an A320 tube into it.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:11 pm
by c933103
exFWAOONW wrote:
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.

IIRC the collision resistance is a special requirement for for American trains, as other countries put the effort in upgrading their signal systems so that trains almost never collide in the first place.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:14 pm
by c933103
trpmb6 wrote:
exFWAOONW wrote:
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.


Agreed. I have a unique perspective in that I've run structural analysis on both aircraft and rail cars. The concept is a total non-starter in my view for the reasons we've both pointed out. The two loading requirements are just too differing - there isn't enough overlap to make it a feasible lightweight design.

What about treating each aircraft tube as individual carriage and then attach locomotives before/after them? Given that aircraft tubes without wing nor engines will not have its own propulsion system and one can be sure no one would want to put an entire set of train power system with wheels and all that onto the sky

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:25 pm
by Super80Fan
LVISA wrote:
I wonder if the Pan Am 707 in the background is Plan B... :D


Well in that case I hope they skip Plan A and go straight to Plan B!

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:31 pm
by WeatherPilot
no...

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:44 pm
by Arion640
I didn’t realise it was April 1st.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:47 pm
by stl07
This makes hyperloop look feasible

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 5:54 pm
by UpNAWAy
Not workable in the least, but gates themselves and the aircraft loading and unloading are one of the most inefficient parts of air travel. Some outside the box thinking in that regard is welcomed.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 6:00 pm
by OA940
What.

The.

Actual.

*I wouldn't be saying hell but profanity rules here*

Did they write this to demonstrate the results of brainstorming while under the influence of LSD?

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 6:22 pm
by AirFiero
I seem to recall reading a principal regarding things like flying cars that when you try to combine two modes of transportation, say, cars and airplanes, you get a vehicle that isn’t very good at either.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 6:23 pm
by DarthLobster
Someone’s been watching too much Dr. Who

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 6:26 pm
by evank516
LVISA wrote:
I wonder if the Pan Am 707 in the background is Plan B... :D


I was just going to point that out. Wouldn't be the worst Plan B to exist :lol:

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 7:51 pm
by VSMUT
c933103 wrote:
exFWAOONW wrote:
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.

IIRC the collision resistance is a special requirement for for American trains, as other countries put the effort in upgrading their signal systems so that trains almost never collide in the first place.


There are collision design requirements in the EU as well.

Edit:
https://en.wikipedia.org/wiki/EN_15227

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 8:05 pm
by spacecadet
c933103 wrote:
IIRC the collision resistance is a special requirement for for American trains, as other countries put the effort in upgrading their signal systems so that trains almost never collide in the first place.


No, "collision resistance", by which you mean longitudinal resistance, is a requirement of every train anywhere, because it's not only about collisions. US regulations are just higher than other countries. But all trains are stronger in this particular way than airplanes are. Also, trains have requirements for specific things like skin buckling resistance and sudden external pressure changes that I doubt any current airliner could meet either. (The sudden pressure change when going through a tunnel or passing a foot from another train I'll bet would shatter the outer passenger window panes on basically any airplane. This force is equivalent to swinging a sledgehammer against a window at high speeds.)

Airliners are made to be as light as possible given the aerodynamic forces they have to deal with. Trains are just build to withstand different forces, and while weight matters, it doesn't matter quite as much so most trains are heavier than they probably really need to be (because of things like window size, seat size and comfort, flooring material and interior fittings, etc.) So while you could probably make an airplane that converts to a train, in the same way there are trucks that turn into trains (multimodal is not a new idea), you'd end up with something that's not a very good plane *or* train. It would be a very heavy airplane and a very slow and not very comfortable train. You'd probably have to have some pretty severe speed limits on it.

I think that making it work as a train, where all you'd need would be for it to be just good enough to go those last few miles into city centers, would be less of a problem than making it a workable airplane. The economics of that just wouldn't work if you have to build it to withstand the forces of both an airplane and a train. There's no way it'd make any money.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 8:06 pm
by c933103
VSMUT wrote:
c933103 wrote:
exFWAOONW wrote:
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.

IIRC the collision resistance is a special requirement for for American trains, as other countries put the effort in upgrading their signal systems so that trains almost never collide in the first place.


There are collision design requirements in the EU as well.

Edit:
https://en.wikipedia.org/wiki/EN_15227

According to the article, this EN 15227 is mainly focused on remaining space in driver cabin after crash.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 8:09 pm
by c933103
spacecadet wrote:
c933103 wrote:
IIRC the collision resistance is a special requirement for for American trains, as other countries put the effort in upgrading their signal systems so that trains almost never collide in the first place.


No, "collision resistance", by which you mean longitudinal resistance, is a requirement of every train anywhere, because it's not only about collisions. US regulations are just higher than other countries. But all trains are stronger in this particular way than airplanes are. Also, trains have requirements for specific things like skin buckling resistance and sudden external pressure changes that I doubt any current airliner could meet either. (The sudden pressure change when going through a tunnel or passing a foot from another train I'll bet would shatter the outer passenger window panes on basically any airplane. This force is equivalent to swinging a sledgehammer against a window at high speeds.)

Airliners are made to be as light as possible given the aerodynamic forces they have to deal with. Trains are just build to withstand different forces, and while weight matters, it doesn't matter quite as much so most trains are heavier than they probably really need to be (because of things like window size, seat size and comfort, flooring material and interior fittings, etc.) So while you could probably make an airplane that converts to a train, in the same way there are trucks that turn into trains (multimodal is not a new idea), you'd end up with something that's not a very good plane *or* train. It would be a very heavy airplane and a very slow and not very comfortable train. You'd probably have to have some pretty severe speed limits on it.

I think that making it work as a train, where all you'd need would be for it to be just good enough to go those last few miles into city centers, would be less of a problem than making it a workable airplane. The economics of that just wouldn't work if you have to build it to withstand the forces of both an airplane and a train. There's no way it'd make any money.

I see
When even moving lounge in airport doesn't work, maybe moving cabin on rail which would have even less comfort and even more technical+financial difficulty for a longer transportational distance wouldn't work either

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 8:16 pm
by peterinlisbon
I don't think this idea is practical because it would take a long time to separate the fuselage from the wing, it would increase costs and complexity and airports and train stations would have to be totally redesigned. Although technically it is possible to do this, it is not viable because it would add too much cost. It would also raise a lot of security and safety concerns.

I wonder if something like this could be used in a more limited sense to help aircraft taxi or back out of their stands. Maybe aircraft could travel on some kind of rail or conveyor belt system to reduce fuel consumption.

Re: Proposal: Flying Trains

Posted: Wed Jul 11, 2018 10:16 pm
by kjeld0d
Inventor's Name: Joseph Clickbait

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 12:26 am
by lightsaber
The move people in a cargo container idea is back! The money saved with faster cockpit/wing turn times by picking up a fresh pod only works if the pod is cheaper than a stick built aircraft .

People worry about folding wingtips. What about when they are ejectable cargo?


trpmb6 wrote:
exFWAOONW wrote:
Train cars require resistance to buff forces i.e. longitudinal, when the slack in the coupling runs in at a stop, or God-forbid, a head-on-collision. (current FRA regulations call for a structure capable of resisting around 800,000 lbs of force for a passenger car) A/C do not need to resist buff forces in flight, more bending and torsion as stated above. For the a/c-car to be safe (certifiable), it would have to be extra heavy with all the reinforcements in all directions. I'm afraid that would make it very inefficient in the air.


Agreed. I have a unique perspective in that I've run structural analysis on both aircraft and rail cars. The concept is a total non-starter in my view for the reasons we've both pointed out. The two loading requirements are just too differing - there isn't enough overlap to make it a feasible lightweight design.

The added weight on the airframe to take 9G loads is too much. The added weight of clamps. How to power ground air-conditioning? How to get to you belly (or tail) checked bag?

Enough of being an engineer. I like the people in connexes concept. I cannot figure out how to make it weight competitively versus self loading cargo.

Lightsaber

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 12:34 am
by AtomicGarden
Reminds of a proposal a few years ago of an ejectable cabin with parachutes for emergency landings

smithbs wrote:
Personally I like walking a couple hundred yards after a plane ride.


Absolutely. Have we humans become THAT lazy already?

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 12:53 am
by Utah744
I think we'll see Pigs fly first.

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 1:16 am
by neomax
Hahahaha

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 1:54 am
by GatorClark
LVISA wrote:
I wonder if the Pan Am 707 in the background is Plan B... :D


Oh good I wasn't the only one who noticed that.. Maybe I just read the article wrong or missed something altogether, but I think all this is contingent on the fact that everyone on the plane is going to roughly the same place. What about passengers connecting to another flight? Or needing to use a different rail line out of the airport. I agree with the general consensus that this idea is illogical and improbable.

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 2:48 am
by NameOmitted
This reminds me of some of the alternative options to the Trans-Alaska Pipeline. The most feasible were ice-rated super-tankers. They tried with Manhattan, she was holed 3 times in the attempt. One was tankers made of nuclear powered submarines that could go under the ice-cap. That was downright sensible wen compared to creating an aircraft out of 747 wings that could straddle crude oil tanks, flying them from the North Slope to pipelines elsewhere.

Needless to say, building a pipeline through 800 miles of un-developed northland was by far the most practical solution.

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 5:41 am
by Chemist
Why stop here? Have a submarine train and then you can just rail into the water and cruise to the islands.

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 5:54 am
by neomax
Chemist wrote:
Why stop here? Have a submarine train and then you can just rail into the water and cruise to the islands.


:rotfl:

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 7:10 am
by LockheedBBD
trpmb6 wrote:
https://www.bloombergquint.com/technology/2018/07/11/flying-trains-france-s-akka-technologies-makes-pitch-to-boeing

That's what a French entrepreneur, who's made millions by connecting engineers with industrial groups, is pitching to Boeing Co. and others.



For starters, he's pitching the idea to the wrong company. There is at least one company out there that makes both planes and trains and would be the most suitable for such a venture. :rotfl:

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 9:35 am
by PanHAM
That's about as practical as taking your house to work and back every day. Besides that this craft would have too Major flaws:

Too light to be a train and

too heavy t be an aircraft.

More on the real side, the Basic idea behind it is called intermodal, works for people and cargo as well and is used millions of time every day at so called intermodal centres, aka airports and stations.

best regards
Skytruck
:-)

Re: Proposal: Flying Trains

Posted: Thu Jul 12, 2018 2:37 pm
by EWRandMDW
I recall seeing posts on this site regarding new aircraft where passengers would stand for the duration of the trip. Add a few poles and straps to hang onto and voila, a flying subway car.