Make sure you write them and stop their stupid attempts to go forward with this because it sounds like as close as 2013 we can start to see the introduction of E taxi:rolleyes:

AFAIK, none of the vendors concerned has ever suggested that their systems would provide a braking capability, for the reasons you have described.

Correct, it was merely a "what if" posted here.

Theoretically, a motor could have such a dual use, but it is in my opinion undoable as a practical matter. Even locating a separate motor in the proximity of the wheel brakes gives one pause....imho

So, we are back to the nosewheels ONLY as candidate mounting points. That means the slippery ramp scenario is a limiting factor. We also still have the added weight far forward, being hoisted by the current nosegear hydraulics, and the APU generator limitations...

Wouldn't it be better to have an electric tug that pulled the aircraft all the way to the runway? Why take the heavy tug with you?

+1 .........:ok:

Given the weight of a fully-loaded passenger-jet, it seems highly improbable that an apu is going to deliver a sufficient supply of electrons to spark-up those little 'leccy motors.

You can't beat the laws of physics and some VERY substantial cabling and control-gear would be required,,,,as other posters have stated, that's a lot of extra work for the retraction-hydraulics,-though i suppose a dirty great counterbalance-spring could be devised :\
So, we have to find space for all this weighty tackle which has to be flexible-enough to go upand down with the gear, without fatigueing or breaking it's insulation.

no-one considered hydraulic motors? most tracked excavators use this propulsion-method,'cos just like an aircraft, they have a lot of hydraulic rams to power, so the pipework is already close-by and the motor-weight penalty is a lot less.

I fail to see any advantage in using a hybrid tug....conversion and efficiency losses would be large,-we're back to direct mechanical or hydraulic drive.

A good idea to drive the wheels direct,-using a jet pushing against air is extremely inefficient.....the layout of a tug could possibly be re-thought......it could be much lighter if the nosewheel was "carried" thus using the aircraft's own weight to give the tug traction.

Lithium-iron and li-poly batteries are many times more energy-dense than lead-acid, but their number of operating-cycles is quite limited and,though they can be rapidly charged,this carries a spontaneous-combustion risk.

I'm very sceptical of these professed savings.-sounds like a smart-alec sales pitch.it's also worth considering Cattletruck's observation.......the donks need running-up and t's & p's stabilising before flight anyway, so it does make sense to use at least part of it to manoeuver the aeroplane towards the T/O position.


Very simplistic original pitch made, those are just a few thoughts which have surfaced so far..

A simpler solution would be to wind a clock-like spring in the hubs during the deceleration phase and then make controlled use of that energy while taxiing.

There would however be a need to taxi in reverse.

That type of tug is in wide use already, though I see them mostly at Asian and European airports.

...weigh as much as a Chevy Corvette engine....
a worldwide standard of measure for sure!

Given the test shown in the video it appears that it is possible for those little 'leccy' motors to move an aircraft just on APU.

Jury is still out on wear and tear on the gear retraction and extension mechanisms but the economics of carrying the extra weight are pretty straight forward so if they don't add up companies wont buy them. If the economic stack up then they will.

Having used hydraulic blade fold I would stear clear of hydraulic motors in the wheels it will just end in tears.

All up though it is nice to see someone has thought laterally about a problem and come up with a workable solution.

One small snag is engine warm-up times. Five minutes in many cases - and other types need a minumum time of the ground for automatic fuel switching and testing sequences. The crew are going to have to get the timing right at busy airports and there's going to be no possibility of accepting an earlier slot. This will lead to delays.

As in "be ready for immediate takeoff?"

Would they go "Beep Beep Beep" while reversing?

How long does it typically take to get that goop "nice and runny"?

My typical taxi time these days seems ~30 minutes.....

Time for some schooling!
 

So, with all due respect to all of those on here who have been led to believe that their ideas and concerns have yet to be met, let me fill you in just a bit!

For the most part, if you would take the time to actually sit down and go over each of the products on line and actually pay close attention to detail of the information being shared you may actually learn something. Every company that is developing an E-Taxi system recognizes the need for engine run up time and this has been calculated into the savings and time matrixes. Let's face it, no pilot wants someone else to be in control of his or her aircraft or for that matter let alone an automated tug! We all know that first flight warm up is the longest required by a manufacturer as well as the cool down time after landing. That being said, each aircraft is used anywhere from 4.5 to 6.7 flights per day which means that for 90% of the time, even the warm up is of no consequence.
Nobody, and I mean nobody, wants to use the electric taxi systems as a brake. One of the gentlemen on here had a very good calculation in proving the required braking power but besides that, who wants to heat up a motor just for braking which the aircraft already has!
As for a tug that carries the aircraft, son, that has already been done and you should know that this only reduces the life of the landing gear due to the fact that each time you tow an aircraft in that method it counts as a cycle.
Having an audible reverse noise is simply not an option, considering the decibel level it would need to be to actually be louder than the APU and whatever equipment is operating around the aircraft. THIS IS WHY WE HAVE WING WALKERS BACKING UP BEHIND THE AIRCRAFT!
Roger G, well done! Yes, the economics add up and that is why a number of airlines have already signed on to one of the companies and it seems your observation on the landing gear retraction is well informed!
What you all should realize is that it is not just attaching some dinky motor to the airplane, it is a complete redesign of the wheels themselves! The APU has more power on most aircraft than you would ever believe and that is a fact and as far as I am going to say publicly!
Cockney Steve, it is quite clear that your creative mechanical engineering abilities are hampered deeply by your expert extensive electrical engineering knowledge of the APU. Since we know the latter is simply void so are the rest of your qualities. It is simply apparent that your overall knowledge of the costs and operational restraints of running an airline are just elementary! The cost and savings matrix has hundreds of elements and the savings that are advertised are actually lower than the KNOWN savings because in business you want to have a happy client and not one who feels japed on the sale value!
Dominican, please get a grip, it will be here next year on line and there are many people working on this for a number of multi-billion dollar companies who are generations ahead of you.
Bottom line folks is that yes, it is coming and it is coming very soon. Some of you may start seeing this in your AQP programs soon enough. Others maybe later, who knows, but when things like this change an industry and who it works, one should ready themselves and become as familiar with the technology as possible. A good pilot is not just someone who can manipulate the controls but one who understands all his or her systems and correlation of that knowledge to effectively and safely operate the flight.
I look forward to comments, questions and concerns.
J.

So, with all due respect to all of those on here who have been led to believe that their ideas and concerns have yet to be met, let me fill you in just a bit!

For the most part, if you would take the time to actually sit down and go over each of the products on line and actually pay close attention to detail of the information being shared you may actually learn something. Every company that is developing an E-Taxi system recognizes the need for engine run up time and this has been calculated into the savings and time matrixes. Let's face it, no pilot wants someone else to be in control of his or her aircraft or for that matter let alone an automated tug! We all know that first flight warm up is the longest required by a manufacturer as well as the cool down time after landing. That being said, each aircraft is used anywhere from 4.5 to 6.7 flights per day which means that for 90% of the time, even the warm up is of no consequence.
Nobody, and I mean nobody, wants to use the electric taxi systems as a brake. One of the gentlemen on here had a very good calculation in proving the required braking power but besides that, who wants to heat up a motor just for braking which the aircraft already has!
As for a tug that carries the aircraft, son, that has already been done and you should know that this only reduces the life of the landing gear due to the fact that each time you tow an aircraft in that method it counts as a cycle.
Having an audible reverse noise is simply not an option, considering the decibel level it would need to be to actually be louder than the APU and whatever equipment is operating around the aircraft. THIS IS WHY WE HAVE WING WALKERS BACKING UP BEHIND THE AIRCRAFT!
Roger G, well done! Yes, the economics add up and that is why a number of airlines have already signed on to one of the companies and it seems your observation on the landing gear retraction is well informed!
What you all should realize is that it is not just attaching some dinky motor to the airplane, it is a complete redesign of the wheels themselves! The APU has more power on most aircraft than you would ever believe and that is a fact and as far as I am going to say publicly!
Cockney Steve, it is quite clear that your creative mechanical engineering abilities are hampered deeply by your expert extensive electrical engineering knowledge of the APU. Since we know the latter is simply void so are the rest of your qualities. It is simply apparent that your overall knowledge of the costs and operational restraints of running an airline are just elementary! The cost and savings matrix has hundreds of elements and the savings that are advertised are actually lower than the KNOWN savings because in business you want to have a happy client and not one who feels japed on the sale value!
Dominican, please get a grip, it will be here next year on line and there are many people working on this for a number of multi-billion dollar companies who are generations ahead of you.
Bottom line folks is that yes, it is coming and it is coming very soon. Some of you may start seeing this in your AQP programs soon enough. Others maybe later, who knows, but when things like this change an industry and who it works, one should ready themselves and become as familiar with the technology as possible. A good pilot is not just someone who can manipulate the controls but one who understands all his or her systems and correlation of that knowledge to effectively and safely operate the flight.
I look forward to comments, questions and concerns.

mumbles,

I have a concern...the orderlies appear to have mixed up your meds....

..mummbles......
 

For a person who comes across as mightily impressed with their technical prowess and command of the industry, I would suggest you do not make the elementary blunder of posting your 7th contribution twice, in immediate succession. You made a dumb mistake and your mistake detracts from the credibility you seem to crave.

Gee what a novel thought, it never occurred to any of us to ever pay attention-awfully glad you pointed us in the right direction.

An absolute statement; seems to me every time a maintenance technician opens up a panel we are seceding some control- a lot of control really, as we (pilots) do when we yield to the push back tug. It doesn’t bother me in the least, I learned long ago I don’t have all the answers and I depend on others, who by the way are also professionally competent, to do their jobs.

Quote:

---

As for a tug that carries the aircraft, son, that has already been done

---

OK dad

Quote:

---

Cockney Steve, it is quite clear that your creative mechanical engineering abilities are hampered deeply by your expert extensive electrical engineering knowledge of the APU. Since we know the latter is simply void so are the rest of your qualities. It is simply apparent that your overall knowledge of the costs and operational restraints of running an airline are just elementary!

---

....and.....

Quote:

---

Dominican, please get a grip, it will be here next year on line and there are many people working on this for a number of multi-billion dollar companies who are generations ahead of you.

---

Hey "son" "dad" "mom" or "boy" - whatever: you come across as completely arrogant here as well as being technically challenged by the mysteries of posting on PPRuNe as most people do not post multiple copies of the same post (already mentioned above)-was that done for effect or is it a typical reflection of the “quality” of your work and attention to detail?


There is a wonderful ignore function here on PPRuNe and it looks like I have another addition to my rather short list. The last "mummbles" I heard of was a circus clown. Mummbles have you ever heard of the term "Ugly American", does the shoe fit in Baltimore boy/girl?