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Paris Air Show’s Slowest Plane Could Have Biggest Impact
- dorfsmay 13y agoThat was the next logical steps after Boeing electrifying most of the 787 functions (I'm still wondering why Airbus didn't go with bleedless engines for the 350).
- snogglethorpe 13y agoMy impression was that Airbus quite consciously decided to be a bit more conservative with the A350 after seeing all the problems Boeing had with the 787 switching to a zillion new technologies, all at once...
- dorfsmay 13y agoAirbus had also said that the Boeing was using too much carbon fibre on the 787, saying that it was too new a technology, but they ended up using more of it on the A350. I bet all the newer airplanes will switch to bleedless engines in the near future.
- nealabq 13y agoThe Taxibot system, where a small tug vehicle positions itself under the plane's front wheels, would be very promising if it could be self-driving and fully automated. And think of the cost saving when we get rid of the pilot and cockpit. And heck, let's get rid of the landing gear too, and have the plane drop into a cradle running along underneath the plane on a track to catch the plane. The cradle would also provide a lot of the acceleration of liftoff, and the cradle's liftoff track could climb a few hundred feet like a roller coaster, so maybe the plane's engines could be smaller.
- thedrbrian 13y agoWe could get rid of those pesky complaining meat sacks too. I never quite understood the fiscal arguements for pilotless passenger aircraft. It's not like a single seat fighter jet where you can ditch the pressurisation gear, you've got to still keep the cargo alive no matter how much noise that they make.
- shpxnvz 13y ago> It's not like a single seat fighter jet where you can ditch the pressurisation gear, you've got to still keep the cargo alive no matter how much noise that they make. Furthermore, my understanding is that modern fighter aircraft are generally limited in performance to operational envelope of the human driving it, i.e. most modern fighter airframes are capable of performance that could literally kill a human pilot. Getting rid of the pilot opens up the possibility of gaining significant manoeuvrability.
- carleverett 13y agoIs this a serious response?
- WalterBright 13y agoThe German rocket fighter Me-163 dropped its landing gear after takeoff, and landed on a skid. Of course, the Me-163 had other problems like blowing up on the ascent, or worse, dissolving the pilot if it developed a fuel leak.
- lostlogin 13y agoAt the tail end of the war, those Luftwaffe pilots were flying some pretty damn advanced planes, with some pretty awful inherent problems. But the follow on designs (Mig-15 et al) were in service for quite some time after the war. The rate of advance of German industry despite massive aerial assault and savage ground wars is fascinating. I recommend reading Gitta Sereny's biography of Albert Speer. Among other rather less impressive acts (extent debated, but likely involvement in genocide, definitely involved in slave labour organisation etc) he rearranged German industry such the production increases were occurring right up until the very final stages of the war. The major industrial output declined started about early '45 or late '44 from memory, which given the volume of allied bombs dropped speaks to German organisation, allied bomb accuracy, or both!
- WalterBright 13y agoThe two big problems the Luftwaffe had were their pilots got killed off and could not be replaced, and they could not get fuel. The Allied bombing of the fuel supply was very effective. The Allied bomber forces suffered terrible losses, but there were plenty of replacements and fuel.
- lostlogin 13y agoWas the fuel shortage due to bombing or Russians taking the oil fields? I had thought it was nearly entirely due to Russian advance, but the below article makes it seem otherwise. It quotes Speer saying how effective allies bombings were, but it is dated May 1944, which is quite late in the piece given that the tide turned, although this may have been less clear as it was still pre Normandy (just). Interesting fact from that article - the treaty with Russia gained Germany 4m barrels a year, and the subsequent invasion only gained them about the same. Are the numbers misleading? Did Germany still need to process the oil it imported, making relatively small domestic production less relevant and the processing facilities critical? http://vanrcook.tripod.com/Germanfuelshortage.htm http://vanrcook.tripod.com/Germanfuelshortage.htm
- rdl 13y agoIt would be cool if it had batteries or APU on the cart to power the plane, too (AC, IFE, etc)
- olympus 13y agoI wonder how much weight this adds to the plane. A full jet is often right at the edge of it's envelope and adding a few hundred pounds of electric motors could mean that they lose a row of seats. I would love it if extra leg room was an unintended consequence of electric ground propulsion.
- smoyer 13y ago"And that includes the 660-pound weight penalty of installing the system on an airplane."
- fishtoaster 13y agoThe context makes it sound like they included the extra weight in fuel calculations, but it's not clear whether they included overall weight capacity. As the parent points out, this probably isn't worth it if they have to cut a row of paying passengers to do it.
- mikeash 13y agoJust carry a bit less cargo. I don't think passenger airplanes are typically limited by weight, but rather volume, when it comes to the number of passengers.
- olympus 13y agoGuessing that an A320 carries about 150 passengers, losing 3-4 of them would still make this worth it, and if they weren't flying 100% full in the first place the lost seats don't cost them anything. It's a neat idea, seems like a relatively safe mod and a way to catch some low hanging fruit. smoyer, thanks for catching the weight. Seems like I have gotten a little too "efficient" with my reading.
- jmharvey 13y agoAn A320 burns about a half pound of fuel per second when taxiing. [1] So it seems plausible that the amount of weight you save on fuel could go a significant part of the way toward offsetting the weight penalty from carrying the extra motors. I suppose if you're pushing the envelope precisely, and push back overweight, count on the taxi burn to get you down to max take-off weight, and plan to land with the legal minimum fuel reserve, then yeah, you'd still pay the full weight penalty. But I'm guessing that most airlines, as a policy, anticipate a range of possible taxi times in calculating their weight and fuel budgets, so significant weight savings should be realized. [1] http://www.mit.edu/~hamsa/pubs/KhadilkarBalakrishnanGNC2011.pdf http://www.mit.edu/~hamsa/pubs/KhadilkarBalakrishnanGNC2011....
- gambiting 13y agoI think the Concorde was the worst offender when it comes to taxing to the runway, if I remember correctly, because its jet engines were hugely inefficient at low speeds, it would burn almost 2 tonnes of fuel just to get to the runway
- ghshephard 13y agoAt 2 tonnes I suspect they would have had someone tow them to the runway rather than run their engines.
- gambiting 13y agoThat's what I thought - if it uses so much fuel, towing it to the runway should always be cheaper, under any circumstances, right? This is mentioned here: https://en.wikipedia.org/wiki/Concorde#Engines https://en.wikipedia.org/wiki/Concorde#Engines and there is a source for that as well.
- dorfsmay 13y ago> if I remember correctly, because its jet engines were hugely inefficient at low speeds Yes, turbojet vs turbofan. Turbojet only become efficient over Mach 1. > the Concorde was the worst offender No, I the SR 71 was worse, it literally leaked fuel: "Similarly, the fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was achieved only when the airframe heated up and expanded several inches. Because of this, and the lack of a fuel sealing system that could handle the thermal expansion of the airframe at extreme temperatures, the aircraft would leak JP-7 jet fuel on the runway." http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird
- kevincennis 13y agoDoes 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 agoWeight 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 agoMaybe 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 agoWrong 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.
- jljljl 13y ago"The companies claim the result is a potential savings of more than 150 gallons during a multi-flight day for an airplane like the A320 or Boeing’s 737. Overall an airplane equipped with the EGTS could cut fuel consumption by four percent over the course of a year." Another step to help reduce the costs of air travel. Follows the trend of airlines and manufacturers choosing to provide more efficient air travel vs faster air travel to consumers: https://medium.com/lift-and-drag/7885a299bca2 https://medium.com/lift-and-drag/7885a299bca2 It's a pretty funny trend since, as both articles suggest, speed is the cooler/sexier technology. Goes to show that it isn't always the cooler inventions that have the greatest impact.
- X9 13y agoBeen also watching WheelTug[1] as a result of Andrew Tobias' interest (and investment) in it[2]. Sounds like they have more customers lined up, but competition already in this market should be a good thing! [1] http://www.wheeltug.gi/ http://www.wheeltug.gi/ [2] http://andrewtobias.com/column/hot-brakes/ http://andrewtobias.com/column/hot-brakes/
- jerrya 13y agoDoes this take away from being able to warm the engines up to prevent thermal shock and/or ensure give them enough run time before takeoff to ensure they are running well?
- marcosscriven 13y agoI had the same latter question myself. As a passenger, I'd rather the engines were running nicely for the few minutes of taxing, thank you very much!
- stcredzero 13y agoI wonder if they could spin up the tires before they hit the tarmac on landing? Think about it: the landing gear tires go from 0 rpm to spinning rapidly enough to carry the plane going about 140 mph in a fraction of a second. That puts the tire under enormous strain, which causes them to blow out all the time. A pre-landing spin-up system might be able to save a lot of petroleum by conserving synthetic rubber.
- Element_ 13y agoI believe the US air force did extensive studies on this back in the 60's and found that tire ware from spinup only accounted for ~<10% of overall wear on the tires. They found most of the stress comes from the act of braking and turning. Also I believe they found the gyroscopic effects of the spinning wheels actually made it more difficult to land the plane... although that may not be an issue anymore with modern avionics and autopilots.
- nether 13y agoThey don't blow out "all the time," that's why you've never experienced a landing with a blow out. Any way this is a FAQ and has been investigated before: > While I was in college at the University of Cincinnati, I was watching television and saw a shot of an aircraft landing. There was the normal boil of tire smoke at touchdown. I had the same thought as your reader. Thinking that I had a great invention on my hands, I did some research in the library. I found some U.S. Government (Air Force or Navy) documents that addressed this issue. They were complete with photographs of a very elaborate test sled designed to accelerate a test tire over various surfaces and measure the effects of load and spinup time. Tests were done also of pre-spinning the tires. Much to my surprise, tire spinup was not a significant factor in tire wear. > Flight crews did not like having almost 1000 lb. of spinning mass ~15 ft below the center of gravity. The special tires made the aircraft very hard to turn, especially at low airspeeds associated with the approach and landing phase. The crews wanted gyroscopes in the cockpit, not under the wings. But it seemed like a good idea at the time. http://archives.sensorsmag.com/articles/0300/14/index.htm http://archives.sensorsmag.com/articles/0300/14/index.htm
- deleted 13y ago
- mehmehshoe 13y agoWouldn't they also have to place an electric air conditioning system on the plane as well? When they disconnect the shore power at the terminal, the air does not come back on until the engines spin up. edit Read the comments on the article page and a reply stated the APU powers the ac. http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Auxiliary_power_unit.html http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Auxilia...
- WalterBright 13y agoThe APU was a nice advance in that it enabled getting rid of the ground cart - which provided power to the airplane when its engines were off, and also provided the electric power needed to start the engines.
- omegant 13y agoAir conditioning and electricity are suplied by the APU, not only by the ground units. For engine start up you must use the air presure(the startup motor is pneumatic not electric), that's why you don't have air conditioning till the engines are running, but you can have it till the moment that you begin pushing back. Also low cost companies try to save every cent so they don't use the APU till they have to start the engines. This can be pretty unconfortable when you have more than 28C inside, but they don't care too much. Edit: redaction.
- zaroth 13y agoI think I like the sound of the Taxibot over installing electric engines which weight 660 lbs on the wheels. It's like a Roomba for push backs :-) I assume the bot autonomously 'docks' with the plane, then the pilot takes over control and pushes back. Then the bot autonomously returns back to its docking station by the jet bridge. I suppose a single bot could do push backs for 3 or 4 neighboring jets, if they're just doing the push back. If it's taxing the jet all the way down the runway, I guess it's more of a 1:1 ratio, and probably a lot more complicated to work the returning units into ground traffic control, to the point where you need to work it into the overall airport design?
- rodgerd 13y agoTaxibots need to be installed in every airport and for every jet at peak capacity. These units go where the jets goes, and are available for exactly the utilised capacity of the airport.
- danmaz74 13y agoOn the other hand, a taxibot would be working most of the time, while this system would be sitting idle most of the time. Not just sitting sitting idle, it would be weighting on the airplane while flying. EDIT: And this system, like the other one, would be just an alternative solution to the plane main engines, so if they were not working, not enough at peak hours, or not available at every airport, it wouldn't be such a big problem.
- snowwrestler 13y agoNo they wouldn't, because planes could still taxi under engine power. If you land at an airport with taxibot, you get a taxibot. If not, just taxi as usual.
- savrajsingh 13y agoAs we've agreed, this is not a new or novel idea, but it does illustrate why the patent system is broken. A quick, cursory search yields a patent from 1994 for the exact same thing. " Preferably, a motor (27, 44) powered by the auxiliary power unit of the aircraft is used to drive the wheels of the landing gear." https://www.google.com/patents/EP0756556B1?cl=en&dq=electric+taxi+aircraft&hl=en&sa=X&ei=pPrFUYG3J6HH0wGJyoGoCQ&ved=0CEgQ6AEwAzgK https://www.google.com/patents/EP0756556B1?cl=en&dq=electric... Search Google Patents for "electric taxi airplane". Even so, there are many subsequent patents on the same overall concept. A broken system.
- bconway 13y agoIs there any evidence that patent issues are what has kept this idea on the sidelines until now?
- tocomment 13y agoCould they also use he motors to spin the wheels up to speed right before landing? I always see a puff of smoke when the wheels first touch the runway. I imagine that wears down the tires pretty quickly?