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Wheel Tug - Cool!

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boestar    600

So how far does the Wheel Tug take them?  to the hold area for the runway?  if so, what happens when they get there and the engine start valve fails to open?  Now you are all the way over to the runway with no engine power to get you out of the way.  In a traditional pushback and engine start the issue would have been found 100 yards from the gate not a mile or more.

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Malcolm    646

Further re possible increased work load for the Cockpit crews.

  • OPINION: Two heads are better than one for take-off checks

OPINION: Two heads are better than one for take-off checks

  • 20 January, 2017
  • SOURCE: Flight International
  • BY: Flight International

Twenty-first century cockpits have a cancer and, so far, there is no cure. Performance calculation and data-entry errors are unpredictable, liable to arise under certain conditions, taking many forms, with differing origins, and they hide, sometimes undetected, in the mathematical complexity of preparation for flight.

“They can happen to anyone. No-one is immune,” stated an Australian safety analysis in 2011.

Short-haul operators are particularly vulnerable. Pressure to squeeze turnaround times and fly more sectors means more opportunity for error.

“There is no single solution to ensure that such errors are always prevented or captured,” the Australian analysis concluded.

But inquiries into a recent spate of EasyJet calculation incidents have highlighted a potentially valuable countermeasure.

Independent calculations of take-off performance by each member of the crew reduces the likelihood of two separate, but identical, errors, and results in a high probability that any mistake will be caught during cross-check.

Air transport has partly built its reputation for safety on the fundamental principle of back-up and redundancy. Until there is a panacea for numerical slips, miscalculation, and old-fashioned brain fade, two heads will still be better than one.

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thor    31
4 hours ago, boestar said:

So how far does the Wheel Tug take them?  to the hold area for the runway?  if so, what happens when they get there and the engine start valve fails to open?  Now you are all the way over to the runway with no engine power to get you out of the way.  In a traditional pushback and engine start the issue would have been found 100 yards from the gate not a mile or more.

I'm just trying to remember the last time I had a start valve problem or any start problem. Yep, six months ago... in the sim. Other than that not for the last 10k hours.

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Malcolm    646

Seems that there is still a possibility that the tug may be replaced, perhaps first on A320s, this idea powers the main gear instead of the nose gear.

Saving Taxi & Pulling Power.jpg
An electrically powered A320 maneuvers at Le Bourget with engine, An electrically powered A320 maneuvers at Le Bourget with engine covers on and no tell-tale shimmer of exhaust. Credit: Eric Drovin/Safran

Saving Taxi & Pulling Power

Operators of narrowbodies and large regional jets may soon have a much more fuel-efficient, economic and environmentally-friendly method of pulling jets into and out of hangars, as well as moving them around tarmacs.

Henry Canaday | Aug 04, 2017

Operators of narrowbodies and large regional jets may soon have a much more fuel-efficient, economic and environmentally-friendly method of pulling jets into and out of hangars, as well as moving them around tarmacs. In early July, Safran Landing Systems signed a Memorandum of Understanding with a subsidiary of China Aviation Supplies Holding Company to promote electric taxiing solutions in China. Safran is developing an electric taxiing system that uses APU power to move airplanes without using main engines or tractors, and it could be used well beyond China.

And the project is well advanced. According to Sylvain Torregrosa, Electric Taxiing sales and marketing manager, the Safran solution is now progressing toward Technology Readiness Level 6. “We are demonstrating the performances of the system under representative environmental conditions,” Torregrosa explains. “This will be the final step of maturity before program launch.”

Safran is working with Airbus at present. And it will launch the system for single-aisle, narrowbody commercial aircraft that operate in high-cycle, short and medium-range, large, congested airports, where usage of electric taxiing will deliver maximum return on investment.

No airlines have signed up yet, but many are showing interest. Safran believes there will be a market over the next 15 years in single-aisle and large regional aircraft with capacity of 90 or more passengers. And the OEM sees potential for both forward-fits and retrofits.

Torregrosa says Safran’s electric taxiing will be better than rival offers for several reasons. First, “it draws upon Safran’s experience of electric power systems and landing gear systems expertise.” Safran’s technology is more mature, and it takes into account aircraft design by powering the main landing gear, not the forward landing gear.

Further, the new system is designed for a full taxi environment, whatever are the runway materials, slopes, weather conditions or speeds required. The Safran marketer argues the system is the only one that maximizes savings from pushbacks, time savings and fuel savings for short-range aircraft. Additional benefits may include improved on time performance, autonomous gate and hangar relocations and reduction in towing incidents and damage to main engines.

Torregrosa cites a report by Envisa, an independent environmental consultant, that estimates electric taxiing can reduce NOx emissions by up to 51%, CO emissions by up to 73% and CO2 by up to 61%, compared with conventional taxiing. “At this stage we estimate net fuel savings alone could be as high as 4% per flight, not including savings from removal of ground tugs.”

All but one very old version of A320-family main landing gear can be equipped with Safran’s electric taxiing. All APUs on the A320 family are compatible with and sized to power the system.

 

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st27    124

Did there study include increased fuel burn in flight from the weight of these systems or did it just look at ground ops??

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Malcolm    646
35 minutes ago, st27 said:

Did there study include increased fuel burn in flight from the weight of these systems or did it just look at ground ops??

 

•Lower Fuel Burn: the electric taxiing system developed by Safran can result in saving up to 4% of total block fuel budget, and may lead to an average of $250.000 savings per aircraft and per year.

https://www.safran-landing-systems.com/systems-equipment/electric-taxiing-0

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DEFCON    684

If they use these devices for backing up you have to wonder how many aircraft will end up on their butts? One incident per year may cost a carrier more than it saves in fuel fleet wide.

 

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Moon The Loon    296

SO MUCH NEGATIVITY!!!

These systems are GREAT innovations - using GPU electrical power to take the aircraft to the hold short line of the runway of departure...What's not to like?

C'mon - extra weight? Vs up to 30 minutes all engine fuel burns while waiting in line? Yes, gate hold procedures help, but these devices improve fuel burns even more.

  • Like 2

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mo32a    284

I lost a bunch of dough investing in Railpower electric trains touted as the next big thing to move train cars around the yard.

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st27    124
Quote

SO MUCH NEGATIVITY!!!

C'mon....it is an airline forum, after all!!!:D

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gator    14

On the surface, this appears to be a good solution. It's not the first time this has been proposed. These might come in handy for short stage lengths and at airports with long delays after pushback. China comes to mind.  

Engines on the A320 must be started 2 minutes prior to takeoff and it takes a couple of minutes to start them. Nobody's going to wait till the last second to start up, so engines will need to be started about 5-6 minutes prior to takeoff (not 3 as stated on the SAFRAN site). On a 15 minute taxi, that means a max of 10 minutes of savings. The difference between APU and a single engine taxi (the SAFRAN site compares the system to to a 2 engine taxi) on a 320 is about 100 kg per hour. So savings would be about 16 kg. This would mostly be consumed on a segment more than 3 hours if the system weighs 100 kg. 

Can't find max speed, but I can't imagine that it would be more than about 15 kts (I probably shouldn't assume). Long straight taxis with engines operating normally allow up to 30 kts. The extra time might actually cost fuel and would certainly increase overall cost (normally considered to be US$50 per minute especially if a flight is behind schedule)

Costs to be considered:

  • Up front cost 
  • Maintenance
  • Extra weight enroute
  • Use of APU vs single engine taxi. 
  • Still need tugs available in case system inop.
  • Still need pushback crew to wingwalk and communicate with flight crew
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