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Pale rider
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THE LAST WORD Pale rider Driverless cars are already in existence. Would riderless motorbikes be a possibility? (Continued)
Our previous answers to this question have generated a whole new mailbag of correspondence. Readers might also like to look at a feature dealing with this question (5 September 2015, p 32) – Ed
gyroscopic effect has been demonstrated rather elegantly by David Jones and later Hugh Hunt. They mounted an extra wheel on a bicycle beside its front wheel but off the ground. This added wheel can be rotated in either direction. When spinning the same way as the front wheel, it has the same angular momentum as it. Even when the extra wheel is spinning several times faster in the opposite direction to the bike wheels – thus more than counteracting the gyroscopic effect of both – the bike remains perfectly rideable and steerable. This is also true when riding without holding on to the handlebars for those who like to show off.
n Motorcycles and bicycles stay upright not because of the gyroscopic effect of the rotating wheels, as an earlier correspondent suggested (3 March), but due to constant steering and adjustments of body position. The former is more important as the rider steers into a potential “Bicycles with tiny wheels that make no gyroscopic fall. Bike geometry can favour or contribution are still hinder this. Gyroscopic effects perfectly rideable” are unimportant except possibly at very high speeds with heavy motorcycle wheels. People have also constructed Tim Lewis bicycles with tiny wheels that Landshipping, Pembrokeshire, UK make almost no gyroscopic contribution. Again, these are n My understanding is that the still perfectly rideable. gyroscopic theory has largely It has been explained to me – been discredited. in somewhat oversimplified It does have a small influence terms – that the main reason for on balance and rideability. But a bike’s stability is that when it compared with the mass of the starts to lean to one side, the engine, transmission, frame, front wheel wants to turn in that tank, fuel and rider, the mass of direction. This causes the bike to the wheels isn’t nearly enough to turn that way, exerting a lateral counter the unstable equilibrium inertial force that pushes the bike of having the centre of mass quite back upright. high up and poised over the two Amusingly, many classic points touching the road. bike owners also ride modern The insignificance of the performance motorcycles that
We pay £25 for every answer published in New Scientist. To answer a question or ask a new one please email [email protected]. Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address. You can also send questions and
answers to The Last Word, New Scientist, 25 Bedford Street, London, WC2E 9ES. New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format and at any time in the future. All unanswered questions and previous questions and answers are at newscientist.com/lastword/
have tiny wheels compared with those on their old Norton, Triumph or BSA bikes. But they simultaneously cling to the myth that scooters are less safe than their old bike because the wheels are smaller. Sam Edge Ringwood, Hampshire, UK n I have to contradict your correspondent who suggested that riderless motorcycles are a way off (3 March). Yamaha has a humanoid robot that can ride a standard motorcycle – and very fast, too. And Honda has created a bike that follows its dismounted rider like a faithful dog. J. Peter Thoeming East Ryde, New South Wales, Australia n A video of Yamaha’s Motobot racing bike versus MotoGP world champion Valentino Rossi suggests the problem is nearly solved (bit.ly/2CKeZoY). Pete Steggle Blenheim, New Zealand Another earlier response asked whether driverless trams are a possibility (3 March). It seems they already exist – Ed n Driverless trams are a distinct possibility because the rails avoid the need for steering, and automatic points manage the route where it joins and separates from others. Collision avoidance systems are already available in cars. Problems do arise in taking on
a driver’s other responsibilities, such as monitoring passenger behaviour, allowing extra time for those who board very slowly or ensuring people don’t get jammed in closing doors. Prospective passengers would need to press a button to stop and board the tram, but might need a password to obviate mischievous operation causing delays. It is all possible, of course, but doubtless someone would find a method of upsetting the system in a way that a diligent human driver could avoid. Peter Peters Sherborne, Dorset, UK n Driverless trams already exist. A number of airports, including Chicago O’Hare and London Gatwick, use driverless shuttles to transport passengers between terminals. These are on reserved tracks, so there is no danger from other users, but it is a start. David Clarke Seaford, East Sussex, UK
This week’s question FLIGHT OF FANTASY
Earlier this year, a flat‑earther launched a ballistic rocket to observe Earth from altitude. If it were indeed flat and shaped like a frisbee, what would his ballistic path look like if he launched near the disc edge and aimed towards the edge? Would it be a parabolic arc or something else? Scott Marshall By email, no address supplied
THE LAST WORD Pale rider Driverless cars are already in existence. Would riderless motorbikes be a possibility? (Continued)
Our previous answers to this question have generated a whole new mailbag of correspondence. Readers might also like to look at a feature dealing with this question (5 September 2015, p 32) – Ed
gyroscopic effect has been demonstrated rather elegantly by David Jones and later Hugh Hunt. They mounted an extra wheel on a bicycle beside its front wheel but off the ground. This added wheel can be rotated in either direction. When spinning the same way as the front wheel, it has the same angular momentum as it. Even when the extra wheel is spinning several times faster in the opposite direction to the bike wheels – thus more than counteracting the gyroscopic effect of both – the bike remains perfectly rideable and steerable. This is also true when riding without holding on to the handlebars for those who like to show off.
n Motorcycles and bicycles stay upright not because of the gyroscopic effect of the rotating wheels, as an earlier correspondent suggested (3 March), but due to constant steering and adjustments of body position. The former is more important as the rider steers into a potential “Bicycles with tiny wheels that make no gyroscopic fall. Bike geometry can favour or contribution are still hinder this. Gyroscopic effects perfectly rideable” are unimportant except possibly at very high speeds with heavy motorcycle wheels. People have also constructed Tim Lewis bicycles with tiny wheels that Landshipping, Pembrokeshire, UK make almost no gyroscopic contribution. Again, these are n My understanding is that the still perfectly rideable. gyroscopic theory has largely It has been explained to me – been discredited. in somewhat oversimplified It does have a small influence terms – that the main reason for on balance and rideability. But a bike’s stability is that when it compared with the mass of the starts to lean to one side, the engine, transmission, frame, front wheel wants to turn in that tank, fuel and rider, the mass of direction. This causes the bike to the wheels isn’t nearly enough to turn that way, exerting a lateral counter the unstable equilibrium inertial force that pushes the bike of having the centre of mass quite back upright. high up and poised over the two Amusingly, many classic points touching the road. bike owners also ride modern The insignificance of the performance motorcycles that
We pay £25 for every answer published in New Scientist. To answer a question or ask a new one please email [email protected]. Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address. You can also send questions and
answers to The Last Word, New Scientist, 25 Bedford Street, London, WC2E 9ES. New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format and at any time in the future. All unanswered questions and previous questions and answers are at newscientist.com/lastword/
have tiny wheels compared with those on their old Norton, Triumph or BSA bikes. But they simultaneously cling to the myth that scooters are less safe than their old bike because the wheels are smaller. Sam Edge Ringwood, Hampshire, UK n I have to contradict your correspondent who suggested that riderless motorcycles are a way off (3 March). Yamaha has a humanoid robot that can ride a standard motorcycle – and very fast, too. And Honda has created a bike that follows its dismounted rider like a faithful dog. J. Peter Thoeming East Ryde, New South Wales, Australia n A video of Yamaha’s Motobot racing bike versus MotoGP world champion Valentino Rossi suggests the problem is nearly solved (bit.ly/2CKeZoY). Pete Steggle Blenheim, New Zealand Another earlier response asked whether driverless trams are a possibility (3 March). It seems they already exist – Ed n Driverless trams are a distinct possibility because the rails avoid the need for steering, and automatic points manage the route where it joins and separates from others. Collision avoidance systems are already available in cars. Problems do arise in taking on
a driver’s other responsibilities, such as monitoring passenger behaviour, allowing extra time for those who board very slowly or ensuring people don’t get jammed in closing doors. Prospective passengers would need to press a button to stop and board the tram, but might need a password to obviate mischievous operation causing delays. It is all possible, of course, but doubtless someone would find a method of upsetting the system in a way that a diligent human driver could avoid. Peter Peters Sherborne, Dorset, UK n Driverless trams already exist. A number of airports, including Chicago O’Hare and London Gatwick, use driverless shuttles to transport passengers between terminals. These are on reserved tracks, so there is no danger from other users, but it is a start. David Clarke Seaford, East Sussex, UK
This week’s question FLIGHT OF FANTASY
Earlier this year, a flat‑earther launched a ballistic rocket to observe Earth from altitude. If it were indeed flat and shaped like a frisbee, what would his ballistic path look like if he launched near the disc edge and aimed towards the edge? Would it be a parabolic arc or something else? Scott Marshall By email, no address supplied