4 ms·

Does anyone have enough knowledge of commercial aviation to explain why this hasn't been done before? To an outsider, it seems like kind of an obvious feature.

neurotech1 13y ago
Weight added to the aircraft (660lb). Another factor is reliability. Wheel or tire damage can bring down an airliner. The Concorde crash. Also a DC-8 crash in Jeddah in 1991 was due to a fire in the wheel well.[1] Even things like entertainment systems cause risk. Swissair Flight 111 went down due to a fire that started in the entertainment system rack, behind the cockpit. [2] [1] http://en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120 http://en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120 [2] http://en.wikipedia.org/wiki/Swissair_Flight_111 http://en.wikipedia.org/wiki/Swissair_Flight_111
- Zenst 13y ago
  Maybe one day they can forget about landing gear and have airport based landing drones which fly up and attach under the plane. Less to go wrong on the plans and if airports have them, them certainly spares to cover situations. Though a long way from now still. Would help too isolate a important system in a fuel effecient way with redundancy added in for landing. But when they put low priority entertainment systems in a position that worst case can effect critical systems does highlight the added risk of being able to watch a movie on the chair infront of you.
  - neurotech1 13y ago
    Wrong solution to wrong problem. The emergency gear extension works in a vast majority of cases. 99% of gear emergencies are minor, and either false warnings, or easily fixed on the ground, with minor or no damage to the jet. Newer jets have wheel well fire "bottles" or extinguishers and sensors to detect problems so the crew can respond appropriately. Aircraft tires are filled with nitrogen for safety. The DC-8 ground crew topped up with air, and not nitrogen, and also flew with under-inflated tires. "Hot brakes" is a relatively common cause of aircraft incidents, and responded to by airport fire services, to avoid major disasters. In the Swissair 111 crash, the entertainment system didn't have the proper isolating breaker installed, and wasn't fully shutdown once it malfunctioned. Placing the racks in a critical cockpit location near pilot oxygen supply lines, was a major flaw in the system design. PS. Running out of fuel waiting for "ground landing gears" would be significantly more likely, as commented below.
  - omegant 13y ago
    I don't think that is a good idea. A simple half hour system fail could let tens of planes in emergency fuel. Also in turbulent weather is not very wise to have something trying to dock into your plane.
  - nradov 13y ago
    That's not practical for landing due to safety concerns. But Airbus has a related proposal for making take offs more efficient with an electric launching sled. http://www.airbus.com/innovation/future-by-airbus/smarter-skies/aircraft-take-off-in-continuous-eco-climb/ http://www.airbus.com/innovation/future-by-airbus/smarter-sk...
deleted 13y ago
[deleted]
deleted 13y ago
[deleted]
standeven 13y ago
I'm guessing the added weight of electric engines and batteries/generators weren't worth the fuel savings until now, thanks to advances in batteries and rising fuel costs.
- homeomorphic 13y ago
  It's powered by the APU, a small jet fuel burning generator that already supplies the plane with electrical power when the engines are off, so there's no need for extra batteries.
eksith 13y ago
Since aviation became an industry, adding more "things" is always circumspect. If you think about it, that makes sense since every new feature, by virtue of being "new", still has to go through a gauntlet of testing, retesting and independent verification (plus Aviation Authority approval from several different countries). There may have been previous attempts that were possibly abandoned until now when technology has finally caught up to the expected reliability. Well, we shall see. If the Boeing battery problems[1] are a hint, it will take actual major use to bring out any bugs. But I'm still hopeful. [1] http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_p...
omegant 13y ago
Airbus 320 pilot here. This is something I've wondered myself for a long time. This same idea of a electric motor on the wheels powered by the APU(auxiliar small turbine for electricity and air presure, is the loud noise you hear when boarding the plane), is what some other pilots and myself have talked about for a long time. Just taking in to account that it makes you autonomous when pushing back and taxing, the long times you spend waiting for take of at the runway, it makes a lot of sense for this kind of planes that spend a lot of the daily time taxing on congested airports. I don't know exactly the reason why it hasn't been done before, I don't think is a weight or technology reason. It surely has seated on a TODO list for a long time, just take into account that in aviation we are way behind in aplication of the latest technology. For example we are still using single chanel radio for comunications with control( this is terribly frustrating and ineficient, it's pretty common to have comunication jams due to excess of traffics on the same frequency). Airplane computers even in new models are still 90s models (very slow but i suppose that stability is worth the boredom). There are a lot of other vintage technologies in aviation, after all every single release to production must be tested and approved by the FAA and EASA. It's the same for all major changes in systems and procedures. That makes all changes and improvements very slow and expensive.
- crazytony 13y ago
  Yep. The air transport industry is very very change (read: risk) averse. The current APUs (except for 787) have traditionally supplied power at 28 VDC and 115 VAC due to the worries about high voltage arcs. They would rather have more current over more copper than higher voltage. I suspect they have added significant wiring and electronics to this A320 to get this to work. I haven't been able to find out if this aircraft has even flown with this rigging much less gone through certification. I bet they could slightly improve this system and get rid of reversers as well (active braking). That being said, I'd imagine ATC to be very wary of the current 130hp system: there is no way you could expedite a move across an active runway at almost 80,000kg MTOW.
  - o1iver 13y ago
    The video at the bottom of the OP shows that plane taking off and landing.

neurotech1 13y ago

Weight added to the aircraft (660lb). Another factor is reliability. Wheel or tire damage can bring down an airliner. The Concorde crash. Also a DC-8 crash in Jeddah in 1991 was due to a fire in the wheel well.[1] Even things like entertainment systems cause risk. Swissair Flight 111 went down due to a fire that started in the entertainment system rack, behind the cockpit. [2] [1] http://en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120 http://en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120 [2] http://en.wikipedia.org/wiki/Swissair_Flight_111 http://en.wikipedia.org/wiki/Swissair_Flight_111

Zenst 13y ago
Maybe one day they can forget about landing gear and have airport based landing drones which fly up and attach under the plane. Less to go wrong on the plans and if airports have them, them certainly spares to cover situations. Though a long way from now still. Would help too isolate a important system in a fuel effecient way with redundancy added in for landing. But when they put low priority entertainment systems in a position that worst case can effect critical systems does highlight the added risk of being able to watch a movie on the chair infront of you.
- neurotech1 13y ago
  Wrong solution to wrong problem. The emergency gear extension works in a vast majority of cases. 99% of gear emergencies are minor, and either false warnings, or easily fixed on the ground, with minor or no damage to the jet. Newer jets have wheel well fire "bottles" or extinguishers and sensors to detect problems so the crew can respond appropriately. Aircraft tires are filled with nitrogen for safety. The DC-8 ground crew topped up with air, and not nitrogen, and also flew with under-inflated tires. "Hot brakes" is a relatively common cause of aircraft incidents, and responded to by airport fire services, to avoid major disasters. In the Swissair 111 crash, the entertainment system didn't have the proper isolating breaker installed, and wasn't fully shutdown once it malfunctioned. Placing the racks in a critical cockpit location near pilot oxygen supply lines, was a major flaw in the system design. PS. Running out of fuel waiting for "ground landing gears" would be significantly more likely, as commented below.
- omegant 13y ago
  I don't think that is a good idea. A simple half hour system fail could let tens of planes in emergency fuel. Also in turbulent weather is not very wise to have something trying to dock into your plane.
- nradov 13y ago
  That's not practical for landing due to safety concerns. But Airbus has a related proposal for making take offs more efficient with an electric launching sled. http://www.airbus.com/innovation/future-by-airbus/smarter-skies/aircraft-take-off-in-continuous-eco-climb/ http://www.airbus.com/innovation/future-by-airbus/smarter-sk...

deleted 13y ago

[deleted]

deleted 13y ago

[deleted]

standeven 13y ago

I'm guessing the added weight of electric engines and batteries/generators weren't worth the fuel savings until now, thanks to advances in batteries and rising fuel costs.

homeomorphic 13y ago
It's powered by the APU, a small jet fuel burning generator that already supplies the plane with electrical power when the engines are off, so there's no need for extra batteries.

eksith 13y ago

Since aviation became an industry, adding more "things" is always circumspect. If you think about it, that makes sense since every new feature, by virtue of being "new", still has to go through a gauntlet of testing, retesting and independent verification (plus Aviation Authority approval from several different countries). There may have been previous attempts that were possibly abandoned until now when technology has finally caught up to the expected reliability. Well, we shall see. If the Boeing battery problems[1] are a hint, it will take actual major use to bring out any bugs. But I'm still hopeful. [1] http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_p...

omegant 13y ago

Airbus 320 pilot here. This is something I've wondered myself for a long time. This same idea of a electric motor on the wheels powered by the APU(auxiliar small turbine for electricity and air presure, is the loud noise you hear when boarding the plane), is what some other pilots and myself have talked about for a long time. Just taking in to account that it makes you autonomous when pushing back and taxing, the long times you spend waiting for take of at the runway, it makes a lot of sense for this kind of planes that spend a lot of the daily time taxing on congested airports. I don't know exactly the reason why it hasn't been done before, I don't think is a weight or technology reason. It surely has seated on a TODO list for a long time, just take into account that in aviation we are way behind in aplication of the latest technology. For example we are still using single chanel radio for comunications with control( this is terribly frustrating and ineficient, it's pretty common to have comunication jams due to excess of traffics on the same frequency). Airplane computers even in new models are still 90s models (very slow but i suppose that stability is worth the boredom). There are a lot of other vintage technologies in aviation, after all every single release to production must be tested and approved by the FAA and EASA. It's the same for all major changes in systems and procedures. That makes all changes and improvements very slow and expensive.

crazytony 13y ago
Yep. The air transport industry is very very change (read: risk) averse. The current APUs (except for 787) have traditionally supplied power at 28 VDC and 115 VAC due to the worries about high voltage arcs. They would rather have more current over more copper than higher voltage. I suspect they have added significant wiring and electronics to this A320 to get this to work. I haven't been able to find out if this aircraft has even flown with this rigging much less gone through certification. I bet they could slightly improve this system and get rid of reversers as well (active braking). That being said, I'd imagine ATC to be very wary of the current 130hp system: there is no way you could expedite a move across an active runway at almost 80,000kg MTOW.
- o1iver 13y ago
  The video at the bottom of the OP shows that plane taking off and landing.