I'm picturing a bicycle duct taped to the side of a Saturn V here... This also reminds me of the Top Gear where they convert a Reliant into a Space Shuttle. http://www.youtube.com/watch?v=_b4WzWFKQ20
Nirav On Wed, Jan 7, 2009 at 10:58 PM, René Dudfield <ren...@gmail.com> wrote: > Would you need rockets pointing left and right too? Then your rocket > bike can go around corners at rocket speed too. > > Fuck tron... rocket bikes for the win! > > > > On Thu, Jan 8, 2009 at 2:53 PM, Ian Mallett <geometr...@gmail.com> wrote: >> Hello, >> >> A little bit ago a idea of attaching a rocket to bike came up (Thank you JP) >> The pygame community is a fun-loving group, so in the interest of fun, let's >> talk about the implications of it in a TOTALLY off-topic thread. :D I >> encourage responses, as I think they will be to the amusement of all >> concerned. >> >> I'll start. >> Yanom points out that the size of these things is pretty big and hence a >> rocket bike would really be "more like attaching your bike to the rocket." >> Because of the bike part, I'm assuming all propulsion is lateral. Let's >> likewise assume that a) the rocket can support itself horizontally this way, >> and b) the bike can hold the whole thing up as well on it's small two >> wheels. We're not working against gravity here, so acceleration is going to >> be considerably higher. The Atlas V, the rocket mentioned, masses >> 546,700kg. A bike masses < about 20kg. The total mass of the apparatus = >> 546,720kg. The first stage of the rocket exerts 4,152,000N of force over a >> 253 second burn time. Let's assume friction is negligible--(and duh, we're >> going to ignite it). >> >> F = MA says that we'll accelerate at approximately 0.77 G (darn was hoping >> for something more) But: >> After 253 seconds, we'll be traveling at about 1.9 kilometers/second = 5.6 >> mach, or fast enough to cross the continental US in about 35 minutes. >> >> BUT...the fuel burned lightens the payload (more specifically, "thrown" out >> the back, thereby pushing the rocket forward (Newton's Third Law)) so we >> actually go faster. >> This kicks us up to over 2.7 km/second = 8 mach, or fast enough to cross the >> continental US is about 24 minutes. >> At the highest acceleration, we get a more severe, but certainly tolerable >> 1.6 Gs. >> See attachment for the program I used to derive this. I didn't bother to do >> calculus--a second by second approximation is good enough. >> >> I actually thought of putting four rockets on this guy so it's balanced--a >> bike with a rocket on one side would be lopsided, duh. Again, for all you >> practical people, shut up :-) Turns out though that the acceleration >> remains nearly the same, which I should have known if I'd thought about it. >> Oh well. >> >> Now, how fast are the bike wheels spinning? At 2.7 km/second, and a wheel >> diameter of 559mm (this is a mountain bike) each wheel will spin at 165,540 >> RPM, which would probably cause a violation of the wheel's structural >> integrity and a catastrophic failure, i.e., the wheel would explode. >> >> All this is interesting, but boring, if you know what I mean--so let's >> calculate what happens when our contraption (let's use the four rocket >> variety) crashes headlong into an invincible wall traveling at 2.7 >> km/second. The total mass just before impact is approximately 1,053,841kg, >> and it's traveling at a good 2.708km/sec. This means that at impact, we >> have a kinetic energy of 3,864,047,133,512j or about 3.8 terajoules. Now >> we're getting somewhere fun! This collision is comparable in scale to a >> small atomic bomb. Now, as far as acceleration goes, a bike is pretty >> short, say 2.5m. When you sit on it, you're probably not longer than 1m >> yourself, meaning you'll come to a full stop in about 0.369 milliseconds, >> equaling a brain-splattering 748,852Gs, which would very probably kill you. >> Moral: don't ride bikes with big rockets into immovable objects. >> >> Which is not to say it isn't done--at least attaching rockets to bikes. >> Actually, the smaller rockets probably work better for pure acceleration. >> This video uses several small rockets and accelerates to 163 m/s in about 5 >> seconds. French people on rocket bikes is always fun. Then there's >> completely random stuff getting shoved by rockets, like buses (rocket only >> helps here), skateboards, small cars and real cars. This German rocket car >> is a fizzle. An unmanned rocket car is launched peculiarly here. Water >> rocket cars still go fast, and for our grand finale, in '76 someone tried to >> jump the St. Lawrence River with a rocket powered Lincoln Continental (skip >> to 2:55), which pretty much disintegrated in midair. >> >> Ian >> >