A paradoxical thought experiment
in [Motorcycles]
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From: Bob Myers on 8 Jul 2010 17:00 The Older Gentleman wrote: > Bob Myers <nospamplease(a)address.invalid> wrote: > >> sean_q_ wrote: >> >>> I wonder if there would be any military applications for something >>> like this. Imagine a high-explosive-laden, satellite or drone-guided >>> Hayabusa tear-assing along at 150 mph across the open desert >>> seeking out enemy targets. A lot more economical than a cruise >>> missile. >> >> First problem that comes to mind, though, is that something >> like that would be too easy for the other side to knock over. >> The guidance system required for a two-wheeled vehicle >> to make it over variable terrain with a reasonable confidence >> of hitting the target, AND remaining stable and able to >> recover from unexpected stuff in the way or the intentional >> attempt to knock it out would be wayyyyy pricy, too. >> > But as a suicide weapon, for use by the Bad Guys, it has its good > points ;-) Yeah, I thought of that variant, too - the kamikaze bike. The cheapest, most sophisticated guidance system I can think of (and one which is readily available, thanks to being produced by unskilled, volunteer labor...;-)) is the human bean. But if you think about it, that really is a scary and quite serious possibility. Bob M.
From: Vito on 8 Jul 2010 17:15 Twibil wrote: > On Jul 8, 4:18 am, "Vito" <v...(a)cfl.rr.com> wrote: >> >> >> I don't think so. A bike must be forced to lean, either by 'body >> english' or counter-steering. > > Oh dear. > > Note: Left to it's own devices, a non-sidecar bike will fall right > over. And this is equally true whether said bike is moving or at rest. > > It's only the kickstand when at rest, or the rider's constant > corrections when moving, that keep it upright. You're joking? I've seen bikes buck their rider off then proceed to the next corner just fine on their own. I assume you have too.
From: Vito on 8 Jul 2010 17:24 tomorrow(a)erols.com wrote: > BZZZT. Wrong. Having "flown" the car on both sidecar rigs I've > owned, once the sidecar is in the air, and as long as it is in the > air, the motorcycle steers via counter-steering (albeit quite > awkwardly). It should be intuitively obvious, bit if it isn't to you, > just try it - it will be very obvious upon practical application. Yes! I can attest to that having accidentally "flown" a sidecar - once! Never again!
From: sean_q_ on 8 Jul 2010 17:26 S'mee wrote: > Not true, not true at all. Below a given speed it can fall over. BUT > past that threshold (about where countersteering takes over) > Gyroscopic precession and gyroscopic forces would prove you wrong. I think the gyro effect is insignificant below very high speeds. As another thought experiment consider a bicycle with wheels of negligible mass (ie near-zero rotational inetria). The bike still steers and handles normally due to the usual steering geometry (self-centering front wheel because of the trail's caster effect) etc. SQ
From: J. Clarke on 8 Jul 2010 17:42
On 7/8/2010 5:26 PM, sean_q_ wrote: > S'mee wrote: > >> Not true, not true at all. Below a given speed it can fall over. BUT >> past that threshold (about where countersteering takes over) >> Gyroscopic precession and gyroscopic forces would prove you wrong. > > I think the gyro effect is insignificant below very high speeds. > As another thought experiment consider a bicycle with wheels > of negligible mass (ie near-zero rotational inetria). > > The bike still steers and handles normally due to the usual > steering geometry (self-centering front wheel because of > the trail's caster effect) etc. Ever play with a bicycle wheel with a couple of handles on the axle? You might find it interesting. |