I hope this video clearly and fully answers everyone's question of *"why can’t they put motors in the wheels or wind vanes on the tires or rims, to have them already rotating up to landing speed so they do not skid and leave behind rubber."*
...then someone asked about replacing the brakes with a regenerative motor that could both move the plane on the ground some and bring it to a stop. It would put power into a battery after engines were started to use to spin them up for initial touchdown and make more battery power upon landing as braking force.
@@steprob8692 Good point. F1 kers type systems are in existence that would enable that. Using the hub motors to aid taxying would save fuel also and could also be used for pushback.
@@steprob8692I have wandered why airports could not use robotic electric tugs to move aircraft around on the ground, would cut pollution, fuel consumption and airport noise. Could even be controlled by the pilot with a remote link and take the aircraft for the point of take off. Imagined an autonomous electric tractor that zips around pulling aircraft between their takeoff/landing and their parking spot. Perhaps an obstacle is the pricing model of the airports which now don’t support taxiing aircraft and this cost is currently the job of the airline.
@@steprob8692 Mass of battery, plus mass of copper and iron motor, connecting wire would be either heavy for high amperage, or thin, requiring high, potentially dangerous voltages. Not worth it.
"Every pound or half a kilogram of weight removed from an aircraft can save up to 11,000 gallons of fuel annually for long-haul flights." You had better check you numbers! In 2005 I was a designer on the Airbus A380. Our weight/cost trade estimate was $500/lb./yr. I don't think that figure could have increased by 8800% in the last 19 years.
Yeah, with those 25k/lb/yr would mean it costs the airlines about 9 million in a year for each aircraft just to carry the FO and capt... You'd think they would've done away with pilots by then 😆
With in-hub motor development, I can see replacing the braking mechanisms entirely with in-hub electric motors. Going to need somewhere for all that electricity to get dumped. Then you would get computerized active traction control. It's possible for an in-hub motor to be more reliable than a traditional braking system. Particularly if it has a few sensors in there to give you an early report of possible failure. And still be nearly the equivalent weight. I think it's just a matter of time. But I could be wrong.
I‘m only a pilot, but my rough calculation for an A350-900, an extremely efficient airplane, gave me these numbers: Fuel burn is about 25 % of take-off weight for a leg of ten hours. Two legs per day will burn 50 % of the aircraft’s weight per day or 500 g per kg. So even at 20 hours per day on 350 days and 7,000 flight hours per year it would burn 175 kg more fuel for 1 kg in additional weight. At $ 2.30 per gallon, $ 0.60 per liter or 0.75 per kg that’s a cost of $ 131.25 per kilo additional weight per year. Since the average utilization is more around 4,500 hours per year, fuel savings should be around $ 85 per year for each kg of additional weight. That’s still $ 85,000 per year and ton, or $ 1,700,000 per extra ton over 20 years. I think that sounds totally realistic. There are other benefits of less weight, such as reduced wear and tear, more payload if operating at MTOW (Project Sunrise of Quantas).
FYI : The F7U Cutlass, a late 50s US navy fighter had a pre-spin system for its front wheel. Because it was long and very thin, its front landing gear leg would break upon hitting the deck on arrested carrier landings (faster and more violent than "normal" runway landings). The solution was to run a air hose from one stage of the reactor compressor along the front leg to a vent and blast the front wheel with compressed air to pre-spin it.
This sounds like that one fact about the F8 Crusader I learned about it's angle of incidence, of which one of my A&P teachers said couldn't be changed. Thanks for this.
@@TheGoddamnBacon About the F8U, The wing incidence could be set to +5° for take off and landing to help the pilot see the where he was landing. The F8U-5 (FN) or F8E (FN) post 1962 for the french navy could be set to +7°. (Have a look at the movie "The final countdown" closing credits here on youtube. They show a RF8G with its wing set up for landing!)
Was that nuclear reactor or crystalic fusion bypass? Just messing, thank you for the fun fact Vought could make anything complicated when they could have made it simple.
Having changed a LOT of 747 wheels, I can tell you that you cannot 'spin' a wheel just by hand. There is so much drag from the brake that you simply cannot get the wheel to keep turning after you give it even a hefty spin. It stops as soon as you stop pushing. The loads involved are considerable.
But that's a limitation of the current systems? First of all I hope you realise an electric motor is going to be far far far stronger than you? Second of all if you implement primary breaking via using the same motors as generators, then you can easily detect when they hit the ground and instantly turn them on. Turn the traditional breaks into backups for if something goes wrong. This would have so many benefits, from safety to airport expenses. "if it were possible we'd be doing it already" is also the worst argument. There's countless things we didn't start doing until recently that are really obvious. And the history of airliner safety is filled with "why the hell weren't we doing that before an accident (or multiple) happened?". Innovative things get skipped all the time, especially when you only really have two large scale aircraft companies, and both are slow moving companies (and one has shown that they have developed a terrible company culture, and both have demonstrated that they make illogical choices from time to time.
Electric motors take energy. You have to store or generate that energy. The equipment required for that costs weight. Weight costs fuel. So to save a bit of recoverable rubber you'd be burning way more fuel for every flight.
@@creamwobbly the energy required to spin up those wheels is virtually nothing. The weight costs are also likely to be minimal over the costs of the airline as others have calculated. And it's not just so you can save rubber on landing, you can also have much better breaking control and even put that energy back into something like a battery if you want. Most of all though you'd make the plane be able to drive itself without airport assistance. The money you could save there could be significant over the lifetime of the plane.
Retired Airline Captain, there was a retrofit kit to a small private jet known as a Cessna Citation that would "spin up" just the nose wheel. That aircraft had just a single wheel assembly for the nose gear as most commercial jets usually have two wheel assemblies. But it was used for dirt field operations as a spinning wheel would be less prone to throwing up dust, rocks, and other debris when it touched down at speed. Think of a shovel being thrown into a rock pile at a high speed as opposed to a lower speed? The engines of the Citation were mounted towards the back of the plane on the fuselage and not under the wings. Just like chines on a tire for water, but that's another subject for another vid!
@@brightymcbrightface Well "bright"one, it appears that maybe your interest is peaked on the very drugs you appear to take? What I was referencing was a similar technology to mitigate damage to the aircraft's engines due to foreign object damage. As I recall the system, it has no way to propel the aircraft for taxi operations which was clearly illustrated in the video. Sobriety is your friend.
Gravel runway kit. Kludgy PITA system. Most went to Canada or South America. Gravel guards on belly antennas and flaps also. It slows damage, but doesn’t eliminate. Enough gravel runway landings and belly skins are scrap.
Funny, this was my first thought too. Every counter argument checks out except one- Firestone/Goodyear aren't going to gain a competitive edge by selling *less* rubber...
Tires wear out as a function of mu, or the friction coefficient. The stickier the tire, the more grip it provides, but the faster it wears. Since grip is good for the customer, and more rubber sold is good for tire companies, you'd expect extremely high mu values to be universal. Maybe a mu of 1.9 like those found in racing tires. But strangely most road cars have a mu of closer to 1... Its almost like customers choose tires for their incresed lifespan, and companies actually gain a competitive edge by providing what the customer actually wants, and a tire company that provided excessive mu would go bankrupt. Capitalism works, you just don't understand how.
They do make extra cash off of the used ones too, though. After seeing service on aircraft, they're reprocessed into barrier contraceptives. 🎈 A friend in the industry tells me there are 365 in a Goodyear... 😉
not just about rubber - the shock of 0m/s to 75m/s in a second , is a huge jolt to the entire undercarriage - having wheels spin at even 40m/s would significantly reduce shock loads on the MLG and NLG. The a380 for eg. is notorious for high speed vibrations in the truck, as the wheels spin up initially.
"at even 40m/s" That's about what the USAF found when they studied pre-rotation in the 1950s: Not much benefit (in regard to tire wear anyway) unless spinup reaches about half of the landing speed.
@@marcmcreynolds2827 having worked on landing gears, they are under enormous stresses from every possible angle - reducing one aspect, would help longevity and service life
@@marcmcreynolds2827 not worried about tire wear - but the constant hammering on the undercarriage from 0 - 75m/s - not to mention resonance loads and vibes (which the a380 is bad for)
I think most airline companies are just way too slow to innovate. Motor tech has advanced significantly in the past 30 years, and will further advance in the next comings ones too. So maybe it wasn't feasible with big, heavy, bulky brushed motors from the late 80s, but it is significantly more likely with modern lightweight, reliable BLDC ones nowadays. Probably worth a re-study every 10 years or so with current tech.
The aerospace companies have plenty of engineers and an incentive to make this happen ($$$). I'm sure if/when the pros are more than the cons, it will be done.
in the end it is the same problem as any other economical cost problem. it is cheaper to just buy more than double the amount of rubber than to add something to potentially reduce the cost. that thing could fail regulary under the stresses and add more costs to it than it saved on rubber. the real problems are what we do with shipping. we ship some stuff 3 times around the world and it is still cheaper than to just produce it in one country.
If the taxiing caused more wear on the tires than landing you would see them clearing rubber off the taxi ways, it’s the same as someone burning out in their car, the rubber left on the ground does more damage to the tires than them driving it around all day. Also there are ways of attaching canes to tires that do not require new molds to be made, such as bonding them to the tires after molding
Dad worked for Lockheed back before and into the early WW2 years. They looked into the same problem, with the scarcity of rubber. They found that no amount of spin stopped the smoke and wear on bomber tires. They found it was caused by the transfer of the aircraft weight to the ground. Spinning the tire made it worse. I worked fighters during and just after the Vietnam War. Fighters like the F-105 got something like six or eight landings per tire. Doing touch and go practice landings amounted to doing an approach and not landing, but flyby and go around to save tires.
Thank you for a great to the point video. No asking for likes or subscribe, no silly intro's, no added in video advertisement, no unneeded bla bla narration side steps. Explaining the source of info, explaining the facts short and to the point in a very understandable way. This is how videos should be made always. Perfect video and without you asking you get my like and I did subscribe because now I want to see more from this channel :) Thank you again.
Glad you liked it! and yes I have always hated every aspect of what you stated in other videos, so over the last 8 years of doing youtube, I have always tried making videos this way, even the outro asking to subscribe is a new thing I have never done.
You mentioned the gyroscopic forces on the gear when it's retracting, there's also the centrifugal force of a spinning tyre. This can cause the tyre to expand just enough that it won't fit into the gear bay, or worse, make it jam. One of the first things a new pilot is taught, is to apply the brakes when the aircraft gets airborne, to stop the wheels spinning if they're going to be retracted.
Good video thanks 🤓 My father did his apprenticeship at Vickers Armstrong in the 50’s. He told me this had been briefly explored then, but cost and complication rules it out then too. Tyres are cheap, compared to the development, testing, certification, safety checks, documentation, tyre handling equipment etc. He learned to drive on the Brooklands banking in his lunch hours!
Motors seem too heavy and unreliable, but vanes seems like a great idea. They dont have to spin all the way to aircraft speed, while that would be ideal, any speed difference would decrease rubber transfer. And you tap the brakes on takeoff when you retract regardless, particularly in bad weather. And its not just savings in tires, its savings in closing runways to remove the rubber.
Vanes can spin a nose gear tire (and have), but not a main gear tire with all the inertia from the brake rotors. They wouldn't begin to fit in the wheel well either.
I don't buy the "motors are unreliable" argument. Clearly the landing system works without the motors, so if they were added and failed, the plane could still safely land.
@@finnrock5558 How would you connect the motor to the rolling assembly such that a motor failure wouldn't cause the affected tire to drag or even skid? A moot point, because any amount of weight for a motor (or other) system would cost the operator more than tire flatspotting does... a tire that is going to need replacement anyway at some point from carcass fatigue.
@@ramr7051 Tire pre-rotation was a minor part of my job as an airliner landing gear analysis engineer. I read the research done by the USAF etc, and wrote replies to any would-be inventors of it who contacted my company. See my posts in the pinned thread at the top of the comments for a few more details. I've never done specific calculations regarding what vane size would be needed because there's no point to it, but clearly (to a landing gear dynamicist) they would have to be unreasonably large. Vanes can be made to work on smallish nose tires (and have), but the math is against MLG rolling assemblies. Not just the extra mass from the brake rotors, but also a nasty penalty as size increases: Rotational inertia scales as the cube of a size increase, but vane torque only as the square. As for motors, most of what you need to know on that is encapsulated in the instance when I talking with a German airline about installing for test a prototype safety-related system on one of their widebodies. Once they heard that it would increase the aircraft weight by about 20 kg they backed off: "We'll quote you for the fuel." Tire pre-rotation would easily involve ten times that mass, and for no great benefit other than reducing one aspect of tire wear (braking during rollout can take more off a tire than a bit of rubber reversion from spinup). Hope that helps to answer your question at least somewhat.
The Cessna Citation 560 had an optional gravel kit that included a nose wheel spin-up system that was operated by bleed air from the engines. The purpose was to reduce the amount of debris kicked up by the nose wheel that could potentially be ingested by the engines when landing on unpaved runways.
03:40 great edit timing. This is why I love your channel, you actually care what kind of footage shown, not just slapping generic footage to accompanying the narration.
Vanes wouldn't need to fully spin up the tyres. Small passiv systems would be more than enough, simply avoiding flat spots and thus increasing service life of expensive tyres and slighty reducing rubber on the runway but why would the airline care about rubber on the runway? Also the brakes are more than powerfull enough to stop free spining wheels even with those vanes on them!
The landing gear is lowered a few minutes before the plane lands. By the time it landed, they would have stopped spinning. Plus, spinning tires up to high speed in a wheel well is dangerous to the plane itself.
I had the idea of vanes decades ago. A few years after I thought of the idea I mentioned it to a very successful inventor. He said the savings of the tires was marginal compared to brake wear. Replacing brakes costs more than replacing tires. The energy the tires absorb when landing reduces break wear.
Another thing to think about. The whole idea of the deceleration of landing is the need to remove a tremendous amount of energy from the system. If you spin the wheels before landing, you are adding tremendous amount of energy that now has to be removed during the stop. And adding weight in the apparatus to do so.
I thought of the same thing, I think it enables the airplane to dump a lot of energy quickly, planting it even harder on the runway. Spinning the tires would make it "float" more after touchdown.
@@B.Bogdan I’m an airline pilot myself. 38 years of aviation behind me. Sat by a tire rep one time for our airline on a flight somewhere and had a great discussion. Tire strength and technology is one of the greatest things in aviation, yet it’s never talked about. I’ve logged in the guessing range of something like 20000 landings in my career, without a single tire issue. Multiplied by 6 to 12 tires on each of those landings, that’s a tremendous record of perfection by those installed tires. I can also say with great certainty, that while some of those landings were absolute butter, most were not😂. The 737 aircraft as it’s gone through its generational growth went from the 100000 pound range to nearly twice that weigh, without adding wheels. But the tire technology allowed that to happen. With great success. My hats off to these people behind the scenes that made that safely happen!
Good point. I guess the tire rubber is the first brake. I wonder if adding veins would add any appreciable drag to offset this? Just thinking out loud.
Not sure about that.. If the wheels are prerotated by virtue of fins, the plane linear kinetic energy has been reduced and transferred to the wheels as rotating kinetic energy. Total energy the same. So the brakes have the same total energy to dissipate? If they’re prerotated via motors…different story.
@@ExtrikitOf course the energy used to pre-rotate the wheels would add drag to the aircraft this requiring higher engine power to compensate for the extra drag. No such thing as a free lunch😊
Spent 20 years working on Navy fighter jets. Tires are relatively cheap compared to additional add-on items which add weight and maintenance. Tires are tough. Fighters had 12 ply tires with 24 ply ratings and lasted a surprisingly long time, and are reasonably easy to change, with 350 psi of nitrogen, shipboard ops used 450 psi. And guess what? They recap aircraft tires! Surely, if pre -rotation was a good idea, they would all be doing it by now. It's a good logical question though. And another trivia, when the heavy main wheels are retracted for flight, the brakes come on and lock the wheel so it's not a heavy spinning gyroscope, which would cause control issues. Brakes release again when gear down of course.
Watching the ramp agent stacking luggage, reminds me of my days with Northwest Airlines. In some of the 757's, we had the "magic carpet" systems to allow a single agent to stack the entire bin. The telescoping floor was extremely heavy, and were eventually removed to reduce the weight. If you weren't a "worker", you didn't last long. ✈️💪😉
as an FYI, this video is almost completely wrong. the technical reasons given by the video are all solvable. the real reason it isn't done is money which the video never correctly addresses. bottom line, if there was money to be made by doing this, they would do it
I actually really like this channel. I clicked on this expecting a long drawn out explanation until I finally hear the answer, but instead I get the short, yeah they could but they don't, followed by the explanation. I love this so much, you get a sub from me sir.
Thank you. This was a question I had when I was a kid. My Dad tried to answer it by saying "why would you put motors on the wheels? You're trying to slow down, not speed up." That didn't satisfy me at all and it's been bugging me ever since.
I was expecting to be convinced by the explaination but I wasn't. Adding vane to the tires may not bring them to the landing speed but it sure helps by some percentages. Still makes me wonder why they haven't done it.
Three reasons. 1) It adds weight to landing gear 2) Spinning wheels create gyroscopic forces, making the plane handling off. 3) It would add more things to plane that could break down, meaning more maintenance, more technical delays or flight cancellations and keeping the planes longer off the air.
@@RoyalMela the weight and the gyroscopic forces both are miniscule in comparison to the power and weight of the plane and can be completely ignored given the befits they provide. As for things that may breakdown. That is of no concern. A place has more than a million parts and adding one more is not even an issue.
While watching this. I noticed that at the 2:28 mark. I recognized that test equipment. I ran that dyno for years! Just wondering how they released that footage? But if you are wondering. This was taken at Honeywell aerospace test lab in South Bend, IN. That is the EI dyno, specifically, the B end. This did bring back some great memories of the testing done there.
a few aircraft airliners had a kit to spin up the wheels for use on gravel runways. It used bleed air from the engine to blow the air onto impellers to spin the wheels. This was done to reduce the amount of gravel kicked up upon touchdown, i believe...
In addition to the mentioned points. Wouldn't spinning wheels also be acting like a whole set of gyros? On take-off it was mentioned the wheels are braked to reduce landing gear stresses. On landing with low/ idle power settings it seems like a whole set of spinning wheels would have the potential to be fighting against the control of the aircraft very close to the ground.
It's actually not such a huge issue. The main reason they brake the tyres during gear retraction is to ensure that potential stones and such will not be slung around in the gear bay. Because if you ever have looked at the picture of an aircraft gear bay, it's not tidy little cavity just for the gear. There's lot's of other stuff going through it or is build into it and you don't wanna get them damaged by flying debris.
There is one very simple reason: With peroration the breaking distance would be extended - not too much, but this is completely against the primary use case to bring the airframe to a full stop after touch down.
There is a nosewheel spin-up STC for the Citation 560 series of business jets. Uses bleed air to speed up the nosewheel for landings on gravel strips to reduce the gravel being spit up on to the aircraft and engines.
I've had this question for a long time and I think I even asked it on one of your other videos. Thank you for explaining it, finally an explanation that makes sense.
TLDW: It's just not worth it! But there are tires with showels that prespinn the tires, they do not reach the landingspeed, but maybe half of it, and that reduces the landing wear on the tires
The ideas I’m about to propose would obviously be a massive engineering feat, but given that we live in an age where we can catch 30 story tall rockets with chopsticks, maybe they’re worth considering?… I wonder if a runway skateboard mechanism or an airplane sized conveyor belt system could be developed for use on the runway side of the problem? This could potentially tackle all the sweet spots of this problem: 1) reduce tire wear 2) reduce runway cleaning 3) reduce ground water and air pollution (not really discussed in your video) 4) definitely would provide an opportunity for rubber companies to make lots of money 5) might be able to make landings safer and more comfortable 6) possibly would enable planes to operate with lighter duty tires that are mostly needed for relatively low impact taxiing 7) lighter duty tires would mean less maintenance costs, less replacement costs, less weight, less fuel. This topic is really fascinating to me… another possibility might be to develop commercial sized sea planes and eliminate runways altogether. I’m curious how the operational costs of landing gear compare between similar sized conventional planes vs seaplanes. Problems with all the above ideas may be overcome with existing modern technology. For example, replacing runways with aqueous landing strips would no doubt attract wildlife which would introduce a new problem, surely birds for example could be easily managed with either acoustic pulses or drone deterrents or something? There’s more… what if regarding my skateboard idea, it could actually generate electricity from the planes landing inertia? The Regenerative braking runway?
I will tell you something... spooky. I have never viewed your channel previously (though I am a pilot and airplane owner and subscribe to quite a few aviation related channels). But I was involved in a lawsuit regarding runway damage and the proximate cause was claimed by one side to be excessive pressure in the high-pressure system used to remove rubber on the runway. I thought (literally this morning) "why don't they spin the tires before landing to prevent this?" I spoke to no one about it, it was just a thought in my head, and I'd never heard the concept mentioned or discussed. Yet, I was watching a non-aviation related video, and this one was suggested for me. So, apparently, Google/UA-cam have now hacked into my brain. I hope they enjoy it there, sometimes I personally enjoy it more than at others! Edited to add: all that said, very nice video.
5:57 i have a feeling that this statistic (since it is from the designer) is for an entire product line. half a pound removed from a 737 will save up to 11,000 gallons from ALL 737s.
Also forget something very important. Rotating the wheels with the wind will increase drag and an engine failure on take off at V1 is very very critical. An approach on one engine (for a twin engine airplane or 2 engines for a 4 engines airplane) also needs the less drag as possible. I really doubt that aircraft manufacturers will do such a thing for safety reasons.
As the wheel spins faster, the resistance will be reduced. Even if it wasn't, the amount of drag will be negligible compared to the drag of the undercarriage itself.
@@rus0004 I don't agree. If it was so simple it has been already in use. And the drag won't be negligible. We should ask the question about the drag to an engineer who has already look at this system.
@@denismorissette419 Plenty of things exist in the face of a simple solution purely because of inertia. Do you really think that the drag of a whole landing gear assembly, the open gear bay doors and the gaping chasm that is the gear bay, even the tyres themselves, is going to be even slightly offset by some small turbine blades that reduce their resistance as they move faster (slower compared to the air stream)? Imagine cupping your hand in the wind as you're driving on the freeway. Does your car even notice?
That was an interesting clip of the baggage guy loading the cargo hold. I'd never even considered how they do it once inside the hold. The camera are there, and he is still kind of rough with the suitcases. Imagine what they are like when the cameras are NOT there !
Interesting video, many thanks. Hard to believe that taxiing causes more tire wear than landing. Since every plane lands, this seems to imply that for each and every plane the rubber deposited near touchdown is less than the rubber deposited during that plane's rollout from the gate, takeoff, and return to the gate. For every flight. Accepting that there are other cost/benefit considerations besides loss of tire rubber.
Sounds more like an excuse than an argument if you ask me. Like why do most airplanes still have tail rudders? Well, it's because,.... Old tricks are the best tricks, aren't they?
@@Moakmeister Controlling yaw at the wingtips makes much more sense. Ask any bird. Whatever you're not actively using for yaw control, produces airlift. You can blame the Wright brothers for all those useless tail rudders.
@@Berend-ov8of Can you elaborate? How does a vertical stabilizer / rudder produce airlift? And what would be used instead of it? Wouldn't yaw control on wingtips cause a lof of stress in the wings (since they'll have to rotate the fuselage) and also need to be synchronized on both sides (a way more complex system)? And could they be made strong enough to actually control yaw without banking the plane?
The vanes would not need to spin the wheels all the way up to 160 to have an effect. Even just spinning them up to 30 or 40 mph would have a measurable impact on the tire wear. The tire now only needs to accelerate 120mph instead of 160. Obviously the closer they can get to "full speed", the better, but they aren't completely useless if they don't go super fast.
I don't find the arguments very compelling here, to be honest... We can make small wings not detach randomly, if a brake ignites a fire then we don't care if it burns electric cables or the small wings, with aero devices you can still use the brakes to stop the rotation before retracting the landing gear (brakes are sized to stop the plane, so they can surely stop a single wheel even with aero vanes), it's hard to turn a wheel, sure, but the aero forces acting on these big diameters are also huge. The only valid argument is : what do we gain (a bit more tyre life) vs what is the certification cost (big).
Although you touched on it, the main reason they don't pre-spin the tires is the gyroscopic effect on handling. With the wheels rotating in the vertical plane, when the aircraft rolls left or right, the gyro effect will cause the nose to pitch up or down. When it pitches up or down, the plane will be forced to roll. In other words, at the time that fine control is most critical (final approach and touchdown) the aircraft will be unpredictably pitching and rolling outside of the pilot's inputs. This was the conclusion of an Air Force study of pre-rotation of the landing gear in the 1950's. Short version, the pilots hated it I'd also like to see your data that says you get more wear taxiing than at touchdown. That's counter intuitive since while on the ground, the wheels are just rolling with no sideslip or scraping to speak of.
Pre-spin the wheels in a retracted position before getting out, like using air speed or compressed air. It would be nice to see what speed difference gives half of the tire wear, which could also save cost. On my last short airplane trip, the captain slammed the plane so hard that we bounced back into the air. I guess that is one way to pre-spin the wheels hehe :D
Its not true that tires wear more in taxi than landing, if that was true, then there would be more rubber on the taxiways than the runway, but that isn't the case
Your reasoning is completely wrong. Have you ever seen anybody scraping rubber off of car highways? No, because normal driving (taxiing) creates fine rubber dust and not layers of solid rubber on the surface. Landing is like emergency braking without ABS (or skidding/drifting), which does leave a visual layer of solid rubber.
What about spinning up the wheels while they are inside the plane, by a mechanism that is also inside the plane and just touching the wheels? The spin up mechanism would be touching either special latches on the rim or just by rubbing the rubber. How long would the wheels be able to retain an useful amount of their rotation inertia after being moved to landing position?
Once you take the corrections into account, this seems pretty feasible? Especially if you make the motor the primary breaking system as well, which would directly give the system much better feedback and sensitivity. And the ability for a plane to travel under it's own power throughout the airport can save on fees or expenses. All in all it seems like a good idea to me. Can reduce maintenance, increase safety and reduce pilot workload, and decrease dependency on ground machines etc.
I will admit I've asked myself this question many times in the past during my 59 years on planet earth. Had no idea the rubber build up on the runway required it be scraped off! Knowing that, I am only more curious... resumes video.
Also, safety is a strong point. If a motor or whatsoever gets stuck, or will uncontrollably try to spin the motor? In best case it will cause additional wear of the tire, in worst - runaway excursion, and once on a grass or snow, whatever can happen, even a fire with the loss of life... This risk for the sake of reducing tyre wear? The reply sounds evident 😉
If the wheel motors could do the necessary amount of braking, with the same weight of components, it probably would have been done already. As to the tire manufacturers, they have little incentive to develop a rotation system since the present tires needing retread and replacement so often is good for their business. Engine off taxiing would be great if it could be done with the same mass of components in the wheels. A motor that could do the braking means it would stop the rotation before retraction just as well as brakes do now.
You know those cars you would drag backwards as a kid and then let them go and they fly away due to spring motion? Apply that to airplane tires? Upon take off pilots could switch it on then the wheels would harness that energy and then lock them with brakes. Once tires are deployed for landing again simply release the brakes and the kinetic energy stored would spin up the tires. Thoughts?
well its good but the added resistance would increase fuel consumption, the heavy mechanism would increase weight and imagine if the system broke and all that energy relesed in the air. also the maintenance aspect.
@@nyanuar123 I'm sure they could overcome that with gear ratios, but also it wouldn't need to be all that huge of a resistance? I'm sure spinning the tires up just a little bit is enough to save a bunch of money. They can make the kinetic energy system lightweight as hell too. It doesn't need to be heavy at all.
The answer is because the wear from the skid is insignificant amount of wear, the tyres are worn out by taxiing on the ground, I have changed quite a few and done Michelin training courses
I think the evaluation of the potential benefits of pre-spinning the wheels should be focused on how the runway will get much less (if at all) contaminated with rubber, rather than on saving the tyre's lifespan. Pre-spinning should be important for airports, not aircraft operators.
There systems that involve compressed air taken from the engines, stored in containers and turbines in the wheels that gets initiated during landing, this would spin the tyres up in less than 5 seconds to speed. Its lighter than electric motors, but as someone already mentioned, the problem is when you spin wheels up, you add energy which could mean greater breaking force needed, electric planes would benefit from having an electric motor though as they can use regen alongside breaks to slow down.
Wow what an abstract question, kudos for presenting such an extreme nuanced bit of information. My knowledge of the world is now finally complete 😉. Oh wait, just one more thing can you (or anyone) explain the observer effect on the double slit experiment ?
One possible solution might be to spray a slightly adhesive water-soluble solution onto the tires from a reservoir onboard when landing, this may reduce tire wear and increase grip, reduce runway maintenance, and cool the tires, and wash off the tarmac easily.
@@ThePlayerOfGames Transfer the friction to an intermediate ablative gluelike or plastic substance that would be sprayed onto the tires for during each landing,
@@ThePlayerOfGames sure, why not? The sprayer is not part of the wheel, so no extra complexity there, and the exact level of slippage can be tuned via precise spraying. And if it fails to spray, well thats just the status quo.
I hope this video clearly and fully answers everyone's question of *"why can’t they put motors in the wheels or wind vanes on the tires or rims, to have them already rotating up to landing speed so they do not skid and leave behind rubber."*
...then someone asked about replacing the brakes with a regenerative motor that could both move the plane on the ground some and bring it to a stop. It would put power into a battery after engines were started to use to spin them up for initial touchdown and make more battery power upon landing as braking force.
@@steprob8692 Good point. F1 kers type systems are in existence that would enable that. Using the hub motors to aid taxying would save fuel also and could also be used for pushback.
@@steprob8692I have wandered why airports could not use robotic electric tugs to move aircraft around on the ground, would cut pollution, fuel consumption and airport noise. Could even be controlled by the pilot with a remote link and take the aircraft for the point of take off. Imagined an autonomous electric tractor that zips around pulling aircraft between their takeoff/landing and their parking spot. Perhaps an obstacle is the pricing model of the airports which now don’t support taxiing aircraft and this cost is currently the job of the airline.
I’ve thought of this for years thinking no one else must have thought of it. Great video and shows they were thinking it long before I was born.
@@steprob8692 Mass of battery, plus mass of copper and iron motor, connecting wire would be either heavy for high amperage, or thin, requiring high, potentially dangerous voltages. Not worth it.
"Every pound or half a kilogram of weight removed from an aircraft can save up to 11,000 gallons of fuel annually for long-haul flights." You had better check you numbers! In 2005 I was a designer on the Airbus A380. Our weight/cost trade estimate was $500/lb./yr. I don't think that figure could have increased by 8800% in the last 19 years.
Yeah the numbers in the video seemed quite exaggerated.
Yeah, with those 25k/lb/yr would mean it costs the airlines about 9 million in a year for each aircraft just to carry the FO and capt... You'd think they would've done away with pilots by then 😆
That would be an excellent incentive to introduce weight-loss programmes for staff! I have say that number excited my sanity-check instincts too.
With in-hub motor development, I can see replacing the braking mechanisms entirely with in-hub electric motors. Going to need somewhere for all that electricity to get dumped.
Then you would get computerized active traction control.
It's possible for an in-hub motor to be more reliable than a traditional braking system. Particularly if it has a few sensors in there to give you an early report of possible failure. And still be nearly the equivalent weight.
I think it's just a matter of time. But I could be wrong.
I‘m only a pilot, but my rough calculation for an A350-900, an extremely efficient airplane, gave me these numbers: Fuel burn is about 25 % of take-off weight for a leg of ten hours. Two legs per day will burn 50 % of the aircraft’s weight per day or 500 g per kg. So even at 20 hours per day on 350 days and 7,000 flight hours per year it would burn 175 kg more fuel for 1 kg in additional weight. At $ 2.30 per gallon, $ 0.60 per liter or 0.75 per kg that’s a cost of $ 131.25 per kilo additional weight per year. Since the average utilization is more around 4,500 hours per year, fuel savings should be around $ 85 per year for each kg of additional weight. That’s still $ 85,000 per year and ton, or $ 1,700,000 per extra ton over 20 years. I think that sounds totally realistic. There are other benefits of less weight, such as reduced wear and tear, more payload if operating at MTOW (Project Sunrise of Quantas).
Make Runways out of rubber and airplane tyres out of concrete. Problem solved.
200 mph conveyor belt runways.
😂 Bahaha... I needed that laugh 👍🏻
I'm betting on VTOL airliners.
@@X_Baron Hi . They use a lot more fuel. Cheers, P.R.
Datz....funee
FYI : The F7U Cutlass, a late 50s US navy fighter had a pre-spin system for its front wheel.
Because it was long and very thin, its front landing gear leg would break upon hitting the deck on arrested carrier landings (faster and more violent than "normal" runway landings).
The solution was to run a air hose from one stage of the reactor compressor along the front leg to a vent and blast the front wheel with compressed air to pre-spin it.
This sounds like that one fact about the F8 Crusader I learned about it's angle of incidence, of which one of my A&P teachers said couldn't be changed. Thanks for this.
@@TheGoddamnBacon About the F8U, The wing incidence could be set to +5° for take off and landing to help the pilot see the where he was landing. The F8U-5 (FN) or F8E (FN) post 1962 for the french navy could be set to +7°. (Have a look at the movie "The final countdown" closing credits here on youtube. They show a RF8G with its wing set up for landing!)
Was that nuclear reactor or crystalic fusion bypass? Just messing, thank you for the fun fact Vought could make anything complicated when they could have made it simple.
@@billwendell6886 🤣🤣🤣
A much more elegant solution would be to pre-spin the runway!
Asphalt tires and rubber roads.
Planes landing on a treadmill?
Or land in a net.
@@JoeGator23 😃!!
@@JimC 😃!!!
Having changed a LOT of 747 wheels, I can tell you that you cannot 'spin' a wheel just by hand. There is so much drag from the brake that you simply cannot get the wheel to keep turning after you give it even a hefty spin. It stops as soon as you stop pushing. The loads involved are considerable.
Oh the brakes. Makes sense
But that's a limitation of the current systems? First of all I hope you realise an electric motor is going to be far far far stronger than you? Second of all if you implement primary breaking via using the same motors as generators, then you can easily detect when they hit the ground and instantly turn them on. Turn the traditional breaks into backups for if something goes wrong.
This would have so many benefits, from safety to airport expenses.
"if it were possible we'd be doing it already" is also the worst argument. There's countless things we didn't start doing until recently that are really obvious. And the history of airliner safety is filled with "why the hell weren't we doing that before an accident (or multiple) happened?". Innovative things get skipped all the time, especially when you only really have two large scale aircraft companies, and both are slow moving companies (and one has shown that they have developed a terrible company culture, and both have demonstrated that they make illogical choices from time to time.
Electric motors take energy. You have to store or generate that energy. The equipment required for that costs weight. Weight costs fuel.
So to save a bit of recoverable rubber you'd be burning way more fuel for every flight.
@@creamwobbly the energy required to spin up those wheels is virtually nothing. The weight costs are also likely to be minimal over the costs of the airline as others have calculated. And it's not just so you can save rubber on landing, you can also have much better breaking control and even put that energy back into something like a battery if you want. Most of all though you'd make the plane be able to drive itself without airport assistance. The money you could save there could be significant over the lifetime of the plane.
@@lost4468yt Totally agree
Retired Airline Captain, there was a retrofit kit to a small private jet known as a Cessna Citation that would "spin up" just the nose wheel. That aircraft had just a single wheel assembly for the nose gear as most commercial jets usually have two wheel assemblies. But it was used for dirt field operations as a spinning wheel would be less prone to throwing up dust, rocks, and other debris when it touched down at speed. Think of a shovel being thrown into a rock pile at a high speed as opposed to a lower speed? The engines of the Citation were mounted towards the back of the plane on the fuselage and not under the wings. Just like chines on a tire for water, but that's another subject for another vid!
I worked for a company that has a 560 with the gravel kit in Alaska.
@@brightymcbrightface In Alaska many airports are still gravel.
@@brightymcbrightface Well "bright"one, it appears that maybe your interest is peaked on the very drugs you appear to take? What I was referencing was a similar technology to mitigate damage to the aircraft's engines due to foreign object damage. As I recall the system, it has no way to propel the aircraft for taxi operations which was clearly illustrated in the video. Sobriety is your friend.
Gravel runway kit. Kludgy PITA system. Most went to Canada or South America. Gravel guards on belly antennas and flaps also. It slows damage, but doesn’t eliminate. Enough gravel runway landings and belly skins are scrap.
Everyone says it's not viable until someone makes it viable
"You can't land rockets on a barge and REUSE them! That's just not economically feasible!"
No amount of genius can change the laws of physics.
@@rubiks6 It's physically possible, just not economical. And that's where genius comes in.
yep, and luckily those "everyone" just stick to social media, else there wouldn't be any research and development at all.
@@GeneCash Spaxe x do
Funny, this was my first thought too. Every counter argument checks out except one- Firestone/Goodyear aren't going to gain a competitive edge by selling *less* rubber...
Well, if they had a patented system that would save airlines money, they'd increase market share.
Tires wear out as a function of mu, or the friction coefficient.
The stickier the tire, the more grip it provides, but the faster it wears.
Since grip is good for the customer, and more rubber sold is good for tire companies, you'd expect extremely high mu values to be universal. Maybe a mu of 1.9 like those found in racing tires. But strangely most road cars have a mu of closer to 1...
Its almost like customers choose tires for their incresed lifespan, and companies actually gain a competitive edge by providing what the customer actually wants, and a tire company that provided excessive mu would go bankrupt.
Capitalism works, you just don't understand how.
@@HALLish-jl5mo lol- _"Capitalism works, you just don't understand how"_ There's a fantastic slogan in there.
They do make extra cash off of the used ones too, though. After seeing service on aircraft, they're reprocessed into barrier contraceptives. 🎈
A friend in the industry tells me there are 365 in a Goodyear... 😉
@@HALLish-jl5mo Capitalism sometimes works. Adding some socialism works better.
not just about rubber - the shock of 0m/s to 75m/s in a second , is a huge jolt to the entire undercarriage - having wheels spin at even 40m/s would significantly reduce shock loads on the MLG and NLG.
The a380 for eg. is notorious for high speed vibrations in the truck, as the wheels spin up initially.
"at even 40m/s" That's about what the USAF found when they studied pre-rotation in the 1950s: Not much benefit (in regard to tire wear anyway) unless spinup reaches about half of the landing speed.
@@marcmcreynolds2827 having worked on landing gears, they are under enormous stresses from every possible angle - reducing one aspect, would help longevity and service life
Simple vanes do not need to spin the tires at the correct speed. Any rotational speed will helps. Even if it is only 50% of the required speed.
@@Deontjie agreed
@@marcmcreynolds2827 not worried about tire wear - but the constant hammering on the undercarriage from 0 - 75m/s - not to mention resonance loads and vibes (which the a380 is bad for)
As an engineer, I could pick holes on most of the arguments against in this video. This video was narrated from the against motors/vanes viewpoints.
I think most airline companies are just way too slow to innovate. Motor tech has advanced significantly in the past 30 years, and will further advance in the next comings ones too. So maybe it wasn't feasible with big, heavy, bulky brushed motors from the late 80s, but it is significantly more likely with modern lightweight, reliable BLDC ones nowadays. Probably worth a re-study every 10 years or so with current tech.
Yeah, whoever's making these videos seems to not be an engineer themselves.
@@roboman2444that’s why GA planes use 1950s engine tech!
The aerospace companies have plenty of engineers and an incentive to make this happen ($$$). I'm sure if/when the pros are more than the cons, it will be done.
@@rosadojosean Yeah, Boeing will totally get on it. Totally the leader of airline innovation and safety.
in the end it is the same problem as any other economical cost problem.
it is cheaper to just buy more than double the amount of rubber than to add something to potentially reduce the cost. that thing could fail regulary under the stresses and add more costs to it than it saved on rubber.
the real problems are what we do with shipping. we ship some stuff 3 times around the world and it is still cheaper than to just produce it in one country.
If the taxiing caused more wear on the tires than landing you would see them clearing rubber off the taxi ways, it’s the same as someone burning out in their car, the rubber left on the ground does more damage to the tires than them driving it around all day. Also there are ways of attaching canes to tires that do not require new molds to be made, such as bonding them to the tires after molding
Bonding introduces a point of failure to the tire which molding avoids.
Dad worked for Lockheed back before and into the early WW2 years. They looked into the same problem, with the scarcity of rubber. They found that no amount of spin stopped the smoke and wear on bomber tires. They found it was caused by the transfer of the aircraft weight to the ground. Spinning the tire made it worse.
I worked fighters during and just after the Vietnam War. Fighters like the F-105 got something like six or eight landings per tire. Doing touch and go practice landings amounted to doing an approach and not landing, but flyby and go around to save tires.
Thank you for a great to the point video. No asking for likes or subscribe, no silly intro's, no added in video advertisement, no unneeded bla bla narration side steps. Explaining the source of info, explaining the facts short and to the point in a very understandable way. This is how videos should be made always. Perfect video and without you asking you get my like and I did subscribe because now I want to see more from this channel :) Thank you again.
Glad you liked it! and yes I have always hated every aspect of what you stated in other videos, so over the last 8 years of doing youtube, I have always tried making videos this way, even the outro asking to subscribe is a new thing I have never done.
Am I the only one that *loves* watching commercial landing gear in slow-mo like this? I could watch an hour of it non-stop.
Yep, you are
So is nobody gonna talk about how you're the only one that loves that?
you aint alone no more
My dog also used to love that. But because hes a dog, hes dead now.
Everything is better in slo-mo.
You mentioned the gyroscopic forces on the gear when it's retracting, there's also the centrifugal force of a spinning tyre. This can cause the tyre to expand just enough that it won't fit into the gear bay, or worse, make it jam. One of the first things a new pilot is taught, is to apply the brakes when the aircraft gets airborne, to stop the wheels spinning if they're going to be retracted.
Has anyone had the experience of trying to turn an aircraft in the air with the wheels spinning at 100+ mph? ... the gyroscopic effect is real.
I was taught that from day one, even though it was only a Cessna 150.
On Commercial Jets it's automatically applied once you have weight off wheels.
@@sacr3 I’ve wondered about that, because you never hear pilots say “positive rate, brakes applied, gear up”. 👍
It doesn't brake automatically? Less workload on the pilots.
Good video thanks 🤓
My father did his apprenticeship at Vickers Armstrong in the 50’s. He told me this had been briefly explored then, but cost and complication rules it out then too.
Tyres are cheap, compared to the development, testing, certification, safety checks, documentation, tyre handling equipment etc.
He learned to drive on the Brooklands banking in his lunch hours!
Motors seem too heavy and unreliable, but vanes seems like a great idea. They dont have to spin all the way to aircraft speed, while that would be ideal, any speed difference would decrease rubber transfer. And you tap the brakes on takeoff when you retract regardless, particularly in bad weather.
And its not just savings in tires, its savings in closing runways to remove the rubber.
Vanes can spin a nose gear tire (and have), but not a main gear tire with all the inertia from the brake rotors. They wouldn't begin to fit in the wheel well either.
I don't buy the "motors are unreliable" argument. Clearly the landing system works without the motors, so if they were added and failed, the plane could still safely land.
@@finnrock5558 How would you connect the motor to the rolling assembly such that a motor failure wouldn't cause the affected tire to drag or even skid? A moot point, because any amount of weight for a motor (or other) system would cost the operator more than tire flatspotting does... a tire that is going to need replacement anyway at some point from carcass fatigue.
@@marcmcreynolds2827where's your source for that?
@@ramr7051 Tire pre-rotation was a minor part of my job as an airliner landing gear analysis engineer. I read the research done by the USAF etc, and wrote replies to any would-be inventors of it who contacted my company. See my posts in the pinned thread at the top of the comments for a few more details.
I've never done specific calculations regarding what vane size would be needed because there's no point to it, but clearly (to a landing gear dynamicist) they would have to be unreasonably large. Vanes can be made to work on smallish nose tires (and have), but the math is against MLG rolling assemblies. Not just the extra mass from the brake rotors, but also a nasty penalty as size increases: Rotational inertia scales as the cube of a size increase, but vane torque only as the square.
As for motors, most of what you need to know on that is encapsulated in the instance when I talking with a German airline about installing for test a prototype safety-related system on one of their widebodies. Once they heard that it would increase the aircraft weight by about 20 kg they backed off: "We'll quote you for the fuel." Tire pre-rotation would easily involve ten times that mass, and for no great benefit other than reducing one aspect of tire wear (braking during rollout can take more off a tire than a bit of rubber reversion from spinup).
Hope that helps to answer your question at least somewhat.
The Cessna Citation 560 had an optional gravel kit that included a nose wheel spin-up system that was operated by bleed air from the engines. The purpose was to reduce the amount of debris kicked up by the nose wheel that could potentially be ingested by the engines when landing on unpaved runways.
Very nice that you put the simple explanation at the beginning
03:40 great edit timing.
This is why I love your channel, you actually care what kind of footage shown, not just slapping generic footage to accompanying the narration.
A video with a beginning explanation, and its not 20 minutes of filler?! Now sir, you have my attention.
Vanes wouldn't need to fully spin up the tyres. Small passiv systems would be more than enough, simply avoiding flat spots and thus increasing service life of expensive tyres and slighty reducing rubber on the runway but why would the airline care about rubber on the runway?
Also the brakes are more than powerfull enough to stop free spining wheels even with those vanes on them!
Agreed. The brakes only have to stop the tires, not the entire plane.
The USAF/USN would love to not have to close runways for a week to de-rubber them, regardless of the expense.
Yep.
@@natehill8069 In military applications weight is more important and cost less.
They should try for everybodies benefit. Engineering corps do exist
Excellent no nonsense explanation. I also now understand why the attendants are all slim: cost savings.
Pre-spin them in the landing bay using compressed air provided (possibly diverted from the engines).
The landing gear is lowered a few minutes before the plane lands. By the time it landed, they would have stopped spinning. Plus, spinning tires up to high speed in a wheel well is dangerous to the plane itself.
@@m0ther_bra1ned12 Do you want massive spinning objects inside plane fuselage? Me neither.
I had the idea of vanes decades ago. A few years after I thought of the idea I mentioned it to a very successful inventor. He said the savings of the tires was marginal compared to brake wear. Replacing brakes costs more than replacing tires. The energy the tires absorb when landing reduces break wear.
Another thing to think about. The whole idea of the deceleration of landing is the need to remove a tremendous amount of energy from the system. If you spin the wheels before landing, you are adding tremendous amount of energy that now has to be removed during the stop. And adding weight in the apparatus to do so.
I thought of the same thing, I think it enables the airplane to dump a lot of energy quickly, planting it even harder on the runway. Spinning the tires would make it "float" more after touchdown.
@@B.Bogdan I’m an airline pilot myself. 38 years of aviation behind me. Sat by a tire rep one time for our airline on a flight somewhere and had a great discussion. Tire strength and technology is one of the greatest things in aviation, yet it’s never talked about. I’ve logged in the guessing range of something like 20000 landings in my career, without a single tire issue. Multiplied by 6 to 12 tires on each of those landings, that’s a tremendous record of perfection by those installed tires. I can also say with great certainty, that while some of those landings were absolute butter, most were not😂.
The 737 aircraft as it’s gone through its generational growth went from the 100000 pound range to nearly twice that weigh, without adding wheels. But the tire technology allowed that to happen. With great success. My hats off to these people behind the scenes that made that safely happen!
Good point. I guess the tire rubber is the first brake. I wonder if adding veins would add any appreciable drag to offset this? Just thinking out loud.
Not sure about that.. If the wheels are prerotated by virtue of fins, the plane linear kinetic energy has been reduced and transferred to the wheels as rotating kinetic energy. Total energy the same. So the brakes have the same total energy to dissipate? If they’re prerotated via motors…different story.
@@ExtrikitOf course the energy used to pre-rotate the wheels would add drag to the aircraft this requiring higher engine power to compensate for the extra drag. No such thing as a free lunch😊
Spent 20 years working on Navy fighter jets. Tires are relatively cheap compared to additional add-on items which add weight and maintenance. Tires are tough. Fighters had 12 ply tires with 24 ply ratings and lasted a surprisingly long time, and are reasonably easy to change, with 350 psi of nitrogen, shipboard ops used 450 psi. And guess what? They recap aircraft tires! Surely, if pre -rotation was a good idea, they would all be doing it by now. It's a good logical question though. And another trivia, when the heavy main wheels are retracted for flight, the brakes come on and lock the wheel so it's not a heavy spinning gyroscope, which would cause control issues. Brakes release again when gear down of course.
Watching the ramp agent stacking luggage, reminds me of my days with Northwest Airlines. In some of the 757's, we had the "magic carpet" systems to allow a single agent to stack the entire bin. The telescoping floor was extremely heavy, and were eventually removed to reduce the weight. If you weren't a "worker", you didn't last long. ✈️💪😉
As an lifelong airliner mechanic I always wondered this exact thing. Thank you.
Me too.
as an FYI, this video is almost completely wrong. the technical reasons given by the video are all solvable. the real reason it isn't done is money which the video never correctly addresses. bottom line, if there was money to be made by doing this, they would do it
@@86jam184 If the idea is safe, cheap and reliable, it is already on the plane. If the idea is not safe, not cheap and not reliable, it is not.
I actually really like this channel. I clicked on this expecting a long drawn out explanation until I finally hear the answer, but instead I get the short, yeah they could but they don't, followed by the explanation. I love this so much, you get a sub from me sir.
:)
Great explanation from a certification and maintenance point of view. Good job all around!
Thanks!
Thanks for part 2.... I'd like to have more detail on some concepts but it gives you an opportunity for part 3
Thank you. This was a question I had when I was a kid. My Dad tried to answer it by saying "why would you put motors on the wheels? You're trying to slow down, not speed up."
That didn't satisfy me at all and it's been bugging me ever since.
I was expecting to be convinced by the explaination but I wasn't. Adding vane to the tires may not bring them to the landing speed but it sure helps by some percentages. Still makes me wonder why they haven't done it.
how about cost of the modified tires?
Three reasons.
1) It adds weight to landing gear
2) Spinning wheels create gyroscopic forces, making the plane handling off.
3) It would add more things to plane that could break down, meaning more maintenance, more technical delays or flight cancellations and keeping the planes longer off the air.
@@RoyalMela the weight and the gyroscopic forces both are miniscule in comparison to the power and weight of the plane and can be completely ignored given the befits they provide. As for things that may breakdown. That is of no concern. A place has more than a million parts and adding one more is not even an issue.
While watching this.
I noticed that at the 2:28 mark.
I recognized that test equipment.
I ran that dyno for years!
Just wondering how they released that footage?
But if you are wondering. This was taken at Honeywell aerospace test lab in South Bend, IN.
That is the EI dyno, specifically, the B end.
This did bring back some great memories of the testing done there.
a few aircraft airliners had a kit to spin up the wheels for use on gravel runways. It used bleed air from the engine to blow the air onto impellers to spin the wheels. This was done to reduce the amount of gravel kicked up upon touchdown, i believe...
on landing, you probably like the extra drag when contacting the runway, so that is a plus.
In addition to the mentioned points. Wouldn't spinning wheels also be acting like a whole set of gyros? On take-off it was mentioned the wheels are braked to reduce landing gear stresses. On landing with low/ idle power settings it seems like a whole set of spinning wheels would have the potential to be fighting against the control of the aircraft very close to the ground.
It's actually not such a huge issue. The main reason they brake the tyres during gear retraction is to ensure that potential stones and such will not be slung around in the gear bay. Because if you ever have looked at the picture of an aircraft gear bay, it's not tidy little cavity just for the gear. There's lot's of other stuff going through it or is build into it and you don't wanna get them damaged by flying debris.
That is one major reason why you do not want wheels spinning during landing. Those gyro forces are huge.
I was asking me that since a long time - thank you for the detailed answer!
Great video answer! Thanks. I've been thinking about this lot of times.
This is a very informative answer to this question. Thank you.
There is one very simple reason: With peroration the breaking distance would be extended - not too much, but this is completely against the primary use case to bring the airframe to a full stop after touch down.
They add wheel spin up kits for gravel on private jets and you can turn the system on or off.
There is a nosewheel spin-up STC for the Citation 560 series of business jets. Uses bleed air to speed up the nosewheel for landings on gravel strips to reduce the gravel being spit up on to the aircraft and engines.
I've had this question for a long time and I think I even asked it on one of your other videos. Thank you for explaining it, finally an explanation that makes sense.
The reason so many peoples asked the question on "Cleaning Rubber from Runways" video, is why I made this video.
TLDW: It's just not worth it!
But there are tires with showels that prespinn the tires, they do not reach the landingspeed, but maybe half of it, and that reduces the landing wear on the tires
I really like the short answer, long answer format.
The ideas I’m about to propose would obviously be a massive engineering feat, but given that we live in an age where we can catch 30 story tall rockets with chopsticks, maybe they’re worth considering?… I wonder if a runway skateboard mechanism or an airplane sized conveyor belt system could be developed for use on the runway side of the problem? This could potentially tackle all the sweet spots of this problem: 1) reduce tire wear 2) reduce runway cleaning 3) reduce ground water and air pollution (not really discussed in your video) 4) definitely would provide an opportunity for rubber companies to make lots of money 5) might be able to make landings safer and more comfortable 6) possibly would enable planes to operate with lighter duty tires that are mostly needed for relatively low impact taxiing 7) lighter duty tires would mean less maintenance costs, less replacement costs, less weight, less fuel.
This topic is really fascinating to me… another possibility might be to develop commercial sized sea planes and eliminate runways altogether. I’m curious how the operational costs of landing gear compare between similar sized conventional planes vs seaplanes.
Problems with all the above ideas may be overcome with existing modern technology. For example, replacing runways with aqueous landing strips would no doubt attract wildlife which would introduce a new problem, surely birds for example could be easily managed with either acoustic pulses or drone deterrents or something?
There’s more… what if regarding my skateboard idea, it could actually generate electricity from the planes landing inertia? The Regenerative braking runway?
I will tell you something... spooky. I have never viewed your channel previously (though I am a pilot and airplane owner and subscribe to quite a few aviation related channels). But I was involved in a lawsuit regarding runway damage and the proximate cause was claimed by one side to be excessive pressure in the high-pressure system used to remove rubber on the runway. I thought (literally this morning) "why don't they spin the tires before landing to prevent this?" I spoke to no one about it, it was just a thought in my head, and I'd never heard the concept mentioned or discussed. Yet, I was watching a non-aviation related video, and this one was suggested for me. So, apparently, Google/UA-cam have now hacked into my brain. I hope they enjoy it there, sometimes I personally enjoy it more than at others! Edited to add: all that said, very nice video.
I’m thinking that the heating of the rubber when it skids might give better traction. Something like a dragster doing burn outs before doing its run.
Well, I THOUGHT about trying, but it was gonna be too taxiing. Just glad that someone was thinking about tire wind vanes before I was even born. 🤔🤗
5:57 i have a feeling that this statistic (since it is from the designer) is for an entire product line. half a pound removed from a 737 will save up to 11,000 gallons from ALL 737s.
Thanks mate. I have wondered that for a while but never thought about looking into it.
I had not even thought about this topic, until everyone asked the same question on the Cleaning Rubber video.
Bugger. I thought this was my secret idea that was going to make me gloriously rich!
Also forget something very important. Rotating the wheels with the wind will increase drag and an engine failure on take off at V1 is very very critical. An approach on one engine (for a twin engine airplane or 2 engines for a 4 engines airplane) also needs the less drag as possible. I really doubt that aircraft manufacturers will do such a thing for safety reasons.
As the wheel spins faster, the resistance will be reduced. Even if it wasn't, the amount of drag will be negligible compared to the drag of the undercarriage itself.
@@rus0004 I don't agree. If it was so simple it has been already in use. And the drag won't be negligible. We should ask the question about the drag to an engineer who has already look at this system.
@@denismorissette419 Plenty of things exist in the face of a simple solution purely because of inertia.
Do you really think that the drag of a whole landing gear assembly, the open gear bay doors and the gaping chasm that is the gear bay, even the tyres themselves, is going to be even slightly offset by some small turbine blades that reduce their resistance as they move faster (slower compared to the air stream)? Imagine cupping your hand in the wind as you're driving on the freeway. Does your car even notice?
@@rus0004 Maybe you're wright!!
For me, better make slippery runway for the touchdown section & make coarse somewhere else
That was an interesting clip of the baggage guy loading the cargo hold. I'd never even considered how they do it once inside the hold. The camera are there, and he is still kind of rough with the suitcases. Imagine what they are like when the cameras are NOT there !
Next time, use your head when you're packing your suitcase.
I was randomly thinking of this yesterday.. the algorithm has gotten too powerful 🙌🙌
Thank you, I've wondered about this for years.
Thanks for answering a question I have had on my mind for years but was either too busy or too lazy to research. 👍
On an aircraft landing the spinup on touchdown also preheats the tyre so it has more grip for braking.
Interesting video, many thanks.
Hard to believe that taxiing causes more tire wear than landing. Since every plane lands, this seems to imply that for each and every plane the rubber deposited near touchdown is less than the rubber deposited during that plane's rollout from the gate, takeoff, and return to the gate. For every flight.
Accepting that there are other cost/benefit considerations besides loss of tire rubber.
Sounds more like an excuse than an argument if you ask me.
Like why do most airplanes still have tail rudders?
Well, it's because,....
Old tricks are the best tricks, aren't they?
Yeah, because nothing is changed quickly in Aerospace. Some part drawings are decades old and untouched since
What else would they use besides tail rudders?
@@Moakmeister A V-tail rudder potentially
@@Moakmeister Controlling yaw at the wingtips makes much more sense.
Ask any bird.
Whatever you're not actively using for yaw control, produces airlift.
You can blame the Wright brothers for all those useless tail rudders.
@@Berend-ov8of Can you elaborate? How does a vertical stabilizer / rudder produce airlift? And what would be used instead of it? Wouldn't yaw control on wingtips cause a lof of stress in the wings (since they'll have to rotate the fuselage) and also need to be synchronized on both sides (a way more complex system)? And could they be made strong enough to actually control yaw without banking the plane?
The vanes would not need to spin the wheels all the way up to 160 to have an effect. Even just spinning them up to 30 or 40 mph would have a measurable impact on the tire wear. The tire now only needs to accelerate 120mph instead of 160. Obviously the closer they can get to "full speed", the better, but they aren't completely useless if they don't go super fast.
I don't find the arguments very compelling here, to be honest... We can make small wings not detach randomly, if a brake ignites a fire then we don't care if it burns electric cables or the small wings, with aero devices you can still use the brakes to stop the rotation before retracting the landing gear (brakes are sized to stop the plane, so they can surely stop a single wheel even with aero vanes), it's hard to turn a wheel, sure, but the aero forces acting on these big diameters are also huge. The only valid argument is : what do we gain (a bit more tyre life) vs what is the certification cost (big).
Although you touched on it, the main reason they don't pre-spin the tires is the gyroscopic effect on handling. With the wheels rotating in the vertical plane, when the aircraft rolls left or right, the gyro effect will cause the nose to pitch up or down. When it pitches up or down, the plane will be forced to roll. In other words, at the time that fine control is most critical (final approach and touchdown) the aircraft will be unpredictably pitching and rolling outside of the pilot's inputs. This was the conclusion of an Air Force study of pre-rotation of the landing gear in the 1950's. Short version, the pilots hated it
I'd also like to see your data that says you get more wear taxiing than at touchdown. That's counter intuitive since while on the ground, the wheels are just rolling with no sideslip or scraping to speak of.
Excellent video!
Pre-spin the wheels in a retracted position before getting out, like using air speed or compressed air. It would be nice to see what speed difference gives half of the tire wear, which could also save cost. On my last short airplane trip, the captain slammed the plane so hard that we bounced back into the air. I guess that is one way to pre-spin the wheels hehe :D
If it's not broke don't fix it, keep it simple.
If it's not broke, it must be an Airbus... ✈🇫🇷💯😉
Very informative. Thanks for sharing 👍🏼
Its not true that tires wear more in taxi than landing, if that was true, then there would be more rubber on the taxiways than the runway, but that isn't the case
Your reasoning is completely wrong. Have you ever seen anybody scraping rubber off of car highways? No, because normal driving (taxiing) creates fine rubber dust and not layers of solid rubber on the surface. Landing is like emergency braking without ABS (or skidding/drifting), which does leave a visual layer of solid rubber.
Wow, what a well done video. Thank you!
What about spinning up the wheels while they are inside the plane, by a mechanism that is also inside the plane and just touching the wheels?
The spin up mechanism would be touching either special latches on the rim or just by rubbing the rubber.
How long would the wheels be able to retain an useful amount of their rotation inertia after being moved to landing position?
Once you take the corrections into account, this seems pretty feasible? Especially if you make the motor the primary breaking system as well, which would directly give the system much better feedback and sensitivity. And the ability for a plane to travel under it's own power throughout the airport can save on fees or expenses. All in all it seems like a good idea to me. Can reduce maintenance, increase safety and reduce pilot workload, and decrease dependency on ground machines etc.
I will admit I've asked myself this question many times in the past during my 59 years on planet earth. Had no idea the rubber build up on the runway required it be scraped off! Knowing that, I am only more curious... resumes video.
Thanks for the video. Thumbs up.
However, in-wheel motors could save fuel while taxing and also be used as recuperative braking systems, which will help save brake pads.
Been wondering for so long!
Also, safety is a strong point. If a motor or whatsoever gets stuck, or will uncontrollably try to spin the motor? In best case it will cause additional wear of the tire, in worst - runaway excursion, and once on a grass or snow, whatever can happen, even a fire with the loss of life... This risk for the sake of reducing tyre wear? The reply sounds evident 😉
fully explained and everything covered.
If the wheel motors could do the necessary amount of braking, with the same weight of components, it probably would have been done already. As to the tire manufacturers, they have little incentive to develop a rotation system since the present tires needing retread and replacement so often is good for their business. Engine off taxiing would be great if it could be done with the same mass of components in the wheels. A motor that could do the braking means it would stop the rotation before retraction just as well as brakes do now.
You know those cars you would drag backwards as a kid and then let them go and they fly away due to spring motion?
Apply that to airplane tires?
Upon take off pilots could switch it on then the wheels would harness that energy and then lock them with brakes.
Once tires are deployed for landing again simply release the brakes and the kinetic energy stored would spin up the tires.
Thoughts?
well its good but the added resistance would increase fuel consumption, the heavy mechanism would increase weight and imagine if the system broke and all that energy relesed in the air. also the maintenance aspect.
@@nyanuar123 I'm sure they could overcome that with gear ratios, but also it wouldn't need to be all that huge of a resistance? I'm sure spinning the tires up just a little bit is enough to save a bunch of money.
They can make the kinetic energy system lightweight as hell too. It doesn't need to be heavy at all.
The answer is because the wear from the skid is insignificant amount of wear, the tyres are worn out by taxiing on the ground, I have changed quite a few and done Michelin training courses
These arguments didn't catch me.
I'm sure, there is just no pressure to do so. If ...it would be implemented the next day.
This channel must be owned and operated by one of the tire manufacturers....
I think the evaluation of the potential benefits of pre-spinning the wheels should be focused on how the runway will get much less (if at all) contaminated with rubber, rather than on saving the tyre's lifespan. Pre-spinning should be important for airports, not aircraft operators.
TLDW: Rubber is cheaper than fuel.
So is your sister
@@Species5008I agree 💯
well explained. thanks
Thank you sir for the precise explanation 😊
5:18 thats the answer. the bulk of wear occurs during taxiing
There systems that involve compressed air taken from the engines, stored in containers and turbines in the wheels that gets initiated during landing, this would spin the tyres up in less than 5 seconds to speed. Its lighter than electric motors, but as someone already mentioned, the problem is when you spin wheels up, you add energy which could mean greater breaking force needed, electric planes would benefit from having an electric motor though as they can use regen alongside breaks to slow down.
Wow what an abstract question, kudos for presenting such an extreme nuanced bit of information. My knowledge of the world is now finally complete 😉. Oh wait, just one more thing can you (or anyone) explain the observer effect on the double slit experiment ?
Excellant and common sense!
Very interesting vid - thanks!!
Good to see you are gradually covering mote and more aviation topics that the regular aviation channels do not.
subscriber number #760
I actually have no idea what other aviation channels cover, I will have to look into it and see if there are topics I can cover that they are not.
One possible solution might be to spray a slightly adhesive water-soluble solution onto the tires from a reservoir onboard when landing, this may reduce tire wear and increase grip, reduce runway maintenance, and cool the tires, and wash off the tarmac easily.
Your plan is to reduce the friction between the tyres and the runway…
@@ThePlayerOfGames Transfer the friction to an intermediate ablative gluelike or plastic substance that would be sprayed onto the tires for during each landing,
@@ThePlayerOfGames sure, why not? The sprayer is not part of the wheel, so no extra complexity there, and the exact level of slippage can be tuned via precise spraying. And if it fails to spray, well thats just the status quo.
WELL DONE!!!
before i watch this video i'd like to answer the question. Its because they're trying to stop the plane, not build up more momentum.
Interesting video thanks.