Wheeltug - the novel answer to marginal airline profitability
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Spot on Rainboe. Slowly does it. There is very sophisticated software running the system to avoid various problems. WT will not turn an aircraft into a dragster!
I think Short Circuit blew a fuse...
Logical thinking Christiaan. Except WT have done quite a bit since the Proof of Concept. Your right about numerous scenarios, usable system, valid business case. We do have many more 'ideas'. Some equally as advanced as WT, which is a specific end use for one of many in house technologies. The Chorus Motor has much potential.
Tow bars are a constant source of maintenance woes. Hard linking a strut to a tug exposes the strut, mounting and airframe to the full jarring force of the tug. WT is much more gentle.
WT eliminates Jet blast and many FOD issues. Jet engines run on the ground act as giant vacuum cleaners for grit etc. NOT desirable. Some urban airports are now brining in limits as to the total ground noise envelope. Others have noise limits with early & late landings; a 10 minute taxi in creating 5 minutes of unnecessary noise (after cool down). Then there is air pollution emanating from airports. Using tugs is expensive too. However traditionally airports don't make a separate charge for their use - yet. Gate & taxiway operations will speed up considerably. WT will be a godsend.
When it comes to dips indentations and ramps etc, these have been factored in. Power usage can be momentarily increased to cope.
NSEU, WT's intent is to eliminate the day to day need for tugs. I shan't be addressing the commercially sensitive issue of pushback method here. Are you aware of the number of accidents directly caused by the use of tugs. Not risks, actual events. It was a proof of concept. The video is Boeing's.
Quite rightly WT were not allowed to interfere with ANY on-board systems. Hence the need for a separate power supply. V0.1 was never intended to be remotely close to V1.0. Boeing / Air Canada were satisfied with the method used to prove the concept. As were/are Delta and numerous others. To visually satisfy lay viewers of the video, the Proof of Concept test would have cost many millions more. Money WT just doesn't have to splash about.
When it comes to the real thing, none of your concerns will be issues. If they were, the project would have ceased by now.
The concept isn't new. There were experiments with hook on diesel motors in the 50's. I guess they floundered because the cost of fuel, noise, and environmental concerns weren't topics in those days.
Have any of you pilots experienced Virgin's towing a/c round airports? It seems to have ceased....
I think Short Circuit blew a fuse...
Logical thinking Christiaan. Except WT have done quite a bit since the Proof of Concept. Your right about numerous scenarios, usable system, valid business case. We do have many more 'ideas'. Some equally as advanced as WT, which is a specific end use for one of many in house technologies. The Chorus Motor has much potential.
Tow bars are a constant source of maintenance woes. Hard linking a strut to a tug exposes the strut, mounting and airframe to the full jarring force of the tug. WT is much more gentle.
WT eliminates Jet blast and many FOD issues. Jet engines run on the ground act as giant vacuum cleaners for grit etc. NOT desirable. Some urban airports are now brining in limits as to the total ground noise envelope. Others have noise limits with early & late landings; a 10 minute taxi in creating 5 minutes of unnecessary noise (after cool down). Then there is air pollution emanating from airports. Using tugs is expensive too. However traditionally airports don't make a separate charge for their use - yet. Gate & taxiway operations will speed up considerably. WT will be a godsend.
When it comes to dips indentations and ramps etc, these have been factored in. Power usage can be momentarily increased to cope.
NSEU, WT's intent is to eliminate the day to day need for tugs. I shan't be addressing the commercially sensitive issue of pushback method here. Are you aware of the number of accidents directly caused by the use of tugs. Not risks, actual events. It was a proof of concept. The video is Boeing's.
Quite rightly WT were not allowed to interfere with ANY on-board systems. Hence the need for a separate power supply. V0.1 was never intended to be remotely close to V1.0. Boeing / Air Canada were satisfied with the method used to prove the concept. As were/are Delta and numerous others. To visually satisfy lay viewers of the video, the Proof of Concept test would have cost many millions more. Money WT just doesn't have to splash about.
When it comes to the real thing, none of your concerns will be issues. If they were, the project would have ceased by now.
The concept isn't new. There were experiments with hook on diesel motors in the 50's. I guess they floundered because the cost of fuel, noise, and environmental concerns weren't topics in those days.
Have any of you pilots experienced Virgin's towing a/c round airports? It seems to have ceased....
Last edited by rahosi; 7th Nov 2007 at 23:23.
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Using tugs is expensive too.
If so, I think this biggest company's hurdle will be Occupational Health and Safety.... then company beancounters after a few million dollar-wingtips have sliced through lightpoles, other aircraft, etc...
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Sorry NSEU after I posted I saw your last. Please see my previous edited post.
WT do know nobody would take up the system. That is IF your concerns were to crystallise.
H&S. First there is the FAA & CAA with certification and an STC. This is where Newport Aeronautical come in. They do such work for the big boys. They know what is feasible.
Airlines are quite protective of their fleets too.
Winglets managed it and that was a flight system!
WT are not amateurs.
WT do know nobody would take up the system. That is IF your concerns were to crystallise.
H&S. First there is the FAA & CAA with certification and an STC. This is where Newport Aeronautical come in. They do such work for the big boys. They know what is feasible.
Airlines are quite protective of their fleets too.
Winglets managed it and that was a flight system!
WT are not amateurs.
Last edited by rahosi; 7th Nov 2007 at 23:49.
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NSEU- you're an avionics engineer? You are arguing a bit out of your sphere of knowledge!
If such a device failed on push, the first thing you would want it to do is gently provide automatic braking. What you must not do is brake the main wheels- that could tip the aeroplane back. We rely on such safety braking systems every time we get in an elevator!
Why would it not be used for pushbacks (if it can hack it)? We used to do powerbacks- starting engines on stand, idle reverse and let it go- steering to ground controllers visual instructions. It works OK, but training required, and the engines tend to ingest debris. The pilot has to follow exact visual instructions from the marshaller. I sat at Dallas and watched AA MD82s doing powerback after powerback most skillfully.
If this company wants to prove itself- good luck to them, let them try. They may just do it. But all the ideas are established procedure at some time or other. It's a complete red herring harping on about failed starts at holding points- everyday aeroplanes have trouble at various places. Just today I took off behind a 757 that abandoned take-off at Stockholm. It happens...people deal with it.
<<If it fails on push, presumably friction of the motor will provide braking?>>
If it fails, wouldn't that be the last thing you would want it to do??? You want the nosewheel to revert to.. a plain and simple nosewheel (at least when the aircraft is moving forward).
I can't imagine this system would ever be used for pushbacks. The pilot would have no idea what is going on behind/under him/her.
If it fails, wouldn't that be the last thing you would want it to do??? You want the nosewheel to revert to.. a plain and simple nosewheel (at least when the aircraft is moving forward).
I can't imagine this system would ever be used for pushbacks. The pilot would have no idea what is going on behind/under him/her.
Why would it not be used for pushbacks (if it can hack it)? We used to do powerbacks- starting engines on stand, idle reverse and let it go- steering to ground controllers visual instructions. It works OK, but training required, and the engines tend to ingest debris. The pilot has to follow exact visual instructions from the marshaller. I sat at Dallas and watched AA MD82s doing powerback after powerback most skillfully.
If this company wants to prove itself- good luck to them, let them try. They may just do it. But all the ideas are established procedure at some time or other. It's a complete red herring harping on about failed starts at holding points- everyday aeroplanes have trouble at various places. Just today I took off behind a 757 that abandoned take-off at Stockholm. It happens...people deal with it.
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Rainboe,
I agree.
Let them try.
I can't see a 200 lbs add-on to the nosewheels provide enough traction in all but the most ideal cases.
I can't see saving a few hundred pounds of taxy fuel as compensating for carrying the equivalent of another passenger or two across the Atlantic.
I'd like to see the sums.
But if we're talking 0.1% or so, the changes in procedures, the necessity to still have push-back trucks on standby, and all that, may well negate any advantages.
See you in 2010.
I agree.
Let them try.
I can't see a 200 lbs add-on to the nosewheels provide enough traction in all but the most ideal cases.
I can't see saving a few hundred pounds of taxy fuel as compensating for carrying the equivalent of another passenger or two across the Atlantic.
I'd like to see the sums.
But if we're talking 0.1% or so, the changes in procedures, the necessity to still have push-back trucks on standby, and all that, may well negate any advantages.
See you in 2010.
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Bear in mind that most electric motors can be used to provide a braking action as well as traction,
Either as a resistive brake i.e. motor used as a generator and power disapated in resistors, though not practical on an a/c through weight,
Or regenerative braking where the generated power is returned to the supply bus, this could work from touch down so it would not remove the braking action from the nose wheels.
As a last ditch an electric motor can go from forward to reverse, again to provide braking action.
Either as a resistive brake i.e. motor used as a generator and power disapated in resistors, though not practical on an a/c through weight,
Or regenerative braking where the generated power is returned to the supply bus, this could work from touch down so it would not remove the braking action from the nose wheels.
As a last ditch an electric motor can go from forward to reverse, again to provide braking action.
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Sorry westlakes....
That makes sense on trams and trains, especially high-speed trains.
It makes no sense whatsoever on aircraft taxying at a few miles an hour.....
...regenerative braking...
It makes no sense whatsoever on aircraft taxying at a few miles an hour.....
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Great debate. It hasn't taken long for this think tank to arrive at many of the salient points.
The financial and environmental numbers can be calculated. Simply, on a 737-700 the savings will be something under $½M per year.....
Safety issues are here.
Oh & sooner than 2010. Plus there will be a constant stream of news along the way.
Prime objectives, Get it working, certified & installed. Deluxe features can wait.
Next time you pilots find yourself twiddling your thumbs during a tug related issue, you'll be thinking, 'roll on WT'.
The financial and environmental numbers can be calculated. Simply, on a 737-700 the savings will be something under $½M per year.....
Safety issues are here.
Many Technical & Corporate issues can be studied on this PowerPoint slide show, as presented at the SAE A-5 Toronto, Towbarless Towing Panel, May 2, 07.
Oh & sooner than 2010. Plus there will be a constant stream of news along the way.
Prime objectives, Get it working, certified & installed. Deluxe features can wait.
Next time you pilots find yourself twiddling your thumbs during a tug related issue, you'll be thinking, 'roll on WT'.
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NSEU- you're an avionics engineer? You are arguing a bit out of your sphere of knowledge!
BTW, if communications break down between the ground and flight deck during a critical part of pushback, what is the procedure to stop the aircraft? (at least with a tug, you can signal the tugdriver to stop... or even if you are in difficulty and are unable to signal the driver, he can see what you are doing at all times). Pushing back a 747, how long would the headset lead have to be before the pilots can see me? (Note: the longer the lead, the more likely it is put strain on the wiring, leading to failure... or to get caught under the wheels)... And just ask me how many times I have called the cockpit only to be told to "standby"....
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Sorry All
I believe I introduced to words ”during push back” in attempt to
highlight one disadvantege of the system.
I guess the system is not designed for that phase of departure,
it is to allow “Taxi” with no engines or possibly 1 of 4 running to and from
the runway to save gas. But, hey, it has produced some good dialogue.
I believe I introduced to words ”during push back” in attempt to
highlight one disadvantege of the system.
I guess the system is not designed for that phase of departure,
it is to allow “Taxi” with no engines or possibly 1 of 4 running to and from
the runway to save gas. But, hey, it has produced some good dialogue.
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Some great dialogue & insight as to the numerous hurdles. Nobody is pretending it is going to be a walk in the park. If it were, I wouldn't be here because the system would already exist! Conversely if there were elementary show stoppers, by now the project would have ceased.
Many of the basic questions can be answered by spending 10 minutes on the web site.
From the preamble
System Overview
Introduction
WheelTug® is a fully integrated ground propulsion system for aircraft. Built into the hubs of the nose wheels, it will give aircraft of all sizes full ground mobility (forward & reverse with steering) without turbines or external tugs. It will not require airframe modifications. It will be powered by the Auxiliary Power Unit (APU) which, while technically a turbine, is designed for this sort of application.
To the:-
Join the team, Involvement can be full or part-time, and does not require relocation or frequent travel.
Many of the basic questions can be answered by spending 10 minutes on the web site.
From the preamble
System Overview
Introduction
WheelTug® is a fully integrated ground propulsion system for aircraft. Built into the hubs of the nose wheels, it will give aircraft of all sizes full ground mobility (forward & reverse with steering) without turbines or external tugs. It will not require airframe modifications. It will be powered by the Auxiliary Power Unit (APU) which, while technically a turbine, is designed for this sort of application.
To the:-
Join the team, Involvement can be full or part-time, and does not require relocation or frequent travel.
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regenerative braking
Yes I know, the only time it could possibly be used would be during touch down (or rejected take off) as part of the overall braking effort.
I was more trying to show that the presence of an electric motor (and no independant brakes on nose wheels) does not mean there is no possibility of "braking" those wheels, again as part of the overall braking action of the aircraft.
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Regenerative Braking
Another issue. The concentration and redistribution of all those braking forces, instead of from the main bogeys, from the front strut, up into the airframe. Would 1st class & flight deck crew object to being used as friction material?
(You might have guessed from my terminology, although I have rudimentary understanding of the issues, it doesn't go much further.)
Last edited by rahosi; 9th Nov 2007 at 09:35. Reason: Clarity
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Well speaking as an LAE I think it sounds like a good idea. We have a lot of ATC slot delays here (flights to LHR) and the thought of being able to release the ground crew at depature time so they can go and do another job, instead of hanging around waiting for the slot sounds like a good idea. We have straight push backs so I see no problem with the crew doing it themselves. But our problem is ice in the winter. The parking stands are also the last places to be swept in the snow, mainly because there are aircraft parked there! We use TBL tractors for pushback, which have a very low mass, and quite often in winter they cannot get enough friction to get the pushback started. Often I am shovelling grit under their wheels so they can get a grip. Some gates have underfloor heating and these are much better, we need it on the other gates.
I see no problem with unsupervised engine starts. Nearly all pushbacks are performed by loaders, not LAEs, and I can't remember the last time we had an incident which would have been handled better with an LAE on the headset.
I think that airlines that operate to crowded airports where you have to wait in line for departure will find this a must have.
I am definitely for it, hope we can afford the leasing costs!
I see no problem with unsupervised engine starts. Nearly all pushbacks are performed by loaders, not LAEs, and I can't remember the last time we had an incident which would have been handled better with an LAE on the headset.
I think that airlines that operate to crowded airports where you have to wait in line for departure will find this a must have.
I am definitely for it, hope we can afford the leasing costs!
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Braking
In theory only!
The use of regenerative braking on the rail system depends on being able to return the power to the supply network. In an a/c, despite the large electrical loads, I agree it could be a non-starter.
Any braking action would be in concert with the main bogeys and forces would be no larger than already imparted on the structure than conventional brakes.
As an example (this would not work in the a/c case) most high speed trains whan braking, first use the regenerative brakes and gradually blend in the conventional brakes as speed reduces - it's about how clever the automation is!
Most electrical motors can operate as a generator with no weight penalty, again it's all in the control equipment
(some windfarms are motors, when required to generate they run up to nearly synchronous speed as a motor the wind then accelerates them to synchronous speed which turns them into a generator)
Not very detailed but I hope this gives an idea of the principle.
The heat dump idea would be the resistive braking mentioned by me earlier - a non-started (or stopper!!!)
The design sketch in the early part of the thread is reminisent of the basic design of a linear motor (I could be way off beam here) that has been rolled up
http://en.wikipedia.org/wiki/Linear_motor
The Maglev trains use electrical braking as their sole means of stopping by control of the motor.
Again only theory from an electrical view point
Of course, to comply with best practice, will a/c fitted with this system also be fitted with reversing lights & an audible warning "CAUTION THIS AIRCRAFT IS REVERSING"
That's a joke by the way
In theory only!
The use of regenerative braking on the rail system depends on being able to return the power to the supply network. In an a/c, despite the large electrical loads, I agree it could be a non-starter.
Any braking action would be in concert with the main bogeys and forces would be no larger than already imparted on the structure than conventional brakes.
As an example (this would not work in the a/c case) most high speed trains whan braking, first use the regenerative brakes and gradually blend in the conventional brakes as speed reduces - it's about how clever the automation is!
Most electrical motors can operate as a generator with no weight penalty, again it's all in the control equipment
(some windfarms are motors, when required to generate they run up to nearly synchronous speed as a motor the wind then accelerates them to synchronous speed which turns them into a generator)
Not very detailed but I hope this gives an idea of the principle.
The heat dump idea would be the resistive braking mentioned by me earlier - a non-started (or stopper!!!)
The design sketch in the early part of the thread is reminisent of the basic design of a linear motor (I could be way off beam here) that has been rolled up
http://en.wikipedia.org/wiki/Linear_motor
The Maglev trains use electrical braking as their sole means of stopping by control of the motor.
Again only theory from an electrical view point
Of course, to comply with best practice, will a/c fitted with this system also be fitted with reversing lights & an audible warning "CAUTION THIS AIRCRAFT IS REVERSING"
That's a joke by the way
Warning Toxic!
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NSEU:
It's all done on hand signals only! It's too dangerous to connect up for it. You have just run through why we used hand signals only for it. Can't you leave the practicalities about pushing to those that know about it, and stick to the technical side?
BTW, if communications break down between the ground and flight deck during a critical part of pushback, what is the procedure to stop the aircraft? (at least with a tug, you can signal the tugdriver to stop... or even if you are in difficulty and are unable to signal the driver, he can see what you are doing at all times). Pushing back a 747, how long would the headset lead have to be before the pilots can see me? (Note: the longer the lead, the more likely it is put strain on the wiring, leading to failure... or to get caught under the wheels)... And just ask me how many times I have called the cockpit only to be told to "standby"....
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Humour first
Communications - cordless phones are pretty cheap
Regenerative - Hook it up like a trolley bus
-----------
The Chorus Motor is one very clever piece of kit. Virtual windings (bit like the Company) that actually harness the normally detrimental harmonics. On the fly it can perform as if many different style of motor, in one, and with greater efficiency than each regular motor/generator. Phenomenal power density. One of the big problems with traditional A/C motors is the size / capacity of the controller to handle the relatively large transient peak power requirements at start up. Industry leading Semikron are handling that side of things. Neat is a word that springs to mind.
Safely too. A DC motor has a failure mode akin to an arc welder. (Thought they banned smoking on flights some while ago). An AC motor fails to a non resistive open circuit state. An AC Chorus® Motor is the nextgen.
If I'm not mistaken, what held Maglev back for a long while, was the complexity of the electronics managing the magnetic field. All electric motors manage magnetic fields. Thus there will always be similarities. Mathematically a linear motor is simply an infinite rotating motor.
Come what may, WT technology has to safely, practically, economically reconcile itself with operations at airports.
I must thank you all for your continuing valued input.
Communications - cordless phones are pretty cheap
Regenerative - Hook it up like a trolley bus
-----------
The Chorus Motor is one very clever piece of kit. Virtual windings (bit like the Company) that actually harness the normally detrimental harmonics. On the fly it can perform as if many different style of motor, in one, and with greater efficiency than each regular motor/generator. Phenomenal power density. One of the big problems with traditional A/C motors is the size / capacity of the controller to handle the relatively large transient peak power requirements at start up. Industry leading Semikron are handling that side of things. Neat is a word that springs to mind.
Safely too. A DC motor has a failure mode akin to an arc welder. (Thought they banned smoking on flights some while ago). An AC motor fails to a non resistive open circuit state. An AC Chorus® Motor is the nextgen.
If I'm not mistaken, what held Maglev back for a long while, was the complexity of the electronics managing the magnetic field. All electric motors manage magnetic fields. Thus there will always be similarities. Mathematically a linear motor is simply an infinite rotating motor.
Come what may, WT technology has to safely, practically, economically reconcile itself with operations at airports.
I must thank you all for your continuing valued input.
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Re reversing lights and "beep, beep, beep".
May well become mandatory.... normally you're alerted, by running engines and a big noisy tug, that something is due to happen. Now you'll have aircraft suddenly and quietly creep up on you !
Maybe we'll see the return of the "man with the red flag" !
rahosi,
On a more serious note, went back to the website and the ppt presentation.
If it works on a 767 it should work on a 737.
And I see WT has Semikron on board... not exactly a fly-by-night company (no pun intended).
May well become mandatory.... normally you're alerted, by running engines and a big noisy tug, that something is due to happen. Now you'll have aircraft suddenly and quietly creep up on you !
Maybe we'll see the return of the "man with the red flag" !
rahosi,
On a more serious note, went back to the website and the ppt presentation.
If it works on a 767 it should work on a 737.
And I see WT has Semikron on board... not exactly a fly-by-night company (no pun intended).
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Drove a new Toyota Prius the other day. Similar problem with the silence in reverse. For a laugh, whilst it was parking itself, I leant out the window and deliberately talked to someone gesticulating with both hands. It rather unnerved him seeing the steering wheel spinning this way & that.
Technology has a way of solving problems.
The 767 was supplied by Air Canada. The 737 will be WTs 1st target.
Re Semikron. Not sure if your comment was an accolade or not. They are worthy.
Fly by night or wire?
Technology has a way of solving problems.
The 767 was supplied by Air Canada. The 737 will be WTs 1st target.
Re Semikron. Not sure if your comment was an accolade or not. They are worthy.
Fly by night or wire?