Rocket Man

at that sort of speed, you'll find it very difficult to utilise the venturi effect to provide any sort of appreciable vacuum. i'd leave the venturi effect for low pressure, high volume applications. how does the system work? i can't really see any link between vacuum pressures and cruise control. i could probably tell you how to do it digitally with minimal equipment (a servo and a bit of a circuit) but a mechanical one sounds so much more exciting.

what applications are you looking at? i know that some cars use the venturi effect to create a greater downforce. and chem labs use all manner of gas jet eductors all based on the venturi effect to flash off liquids in distillation. the higher the vacuum, the harder it gets to make.

ever watched a jet fly over head and listened for it's location? it sounds way behind the point you see it. standing on a beach with a cross wind, the sound seems to come from down wind. from yt's example, the sound appears to come from roughly 10m downwind of the speaker

you can get a 1 farad cap rated to 5v for the purpose, but the battery is cheaper

i bought "electricity and electronics" isbn 0-07-136057-3 it's all reasonably light concepts in the beginning of the book where it intorduces the basic parts but it goes on and takes you right through high end amplifiers and digital electronics with emphasis on calculations. it's about $25US i think it's still in print so you'll have trouble finding an online version.

a reputable electronics shop ought to have decent books on such topics. radio controlled models (the better ones) use very similar technology and mechanisms as the originals. if you research full sized and take a look at the models in the hobby shops you should get a good idea as to what's necessary.

you can make anything fly if you get the centre of mass in the right spot. once it's there it's a case of making it fly like a bird or fly like a brick. rc car parts are like bricks, hobby stores sell better batteries and motors but you can't really go much better than the reciever in a small rc car. if you can manage a rotor to lift the weight of the parts (rather difficult) you're set. all you need is to cancel a few minor forces and balance your chopper.

i had a poke around about it, the most important factor seemed to be a long resonance tube (holds true for most designs

rc car motors are dirt cheap and they're built with heavy materials. you could probably do it but you'd need to drop mass else where. the design most likely to work would be counter rotating blades mounted in minimal styrofoam. that way, the majority of the mass is working. helicopter looking designs are generally reserved for petrol motors or high tech materials.

quite a few satellites had nuclear reactors, they normally used a simmering plutonium core and the seebeck effect, a chunky thermopile. to create a big enough magnetic feild doesn't require much power, i seem to recall it being around 50W, much less than communication satellites

nasa has done a study on the use of an artificial magnetoshpere as a solar sail, they found it had merit but i haven't heard much else

you may have problems with gears in close proximity. most hobby gears are stacked very close together, magnetic ones will rack up quite a lot of vibration. have you considered using a shaped field around a cylinder instead? that would reduce load on the brittle magnetic material and allow a higher rpm to failure as carbon fiber can be wrapped around each gear. it opens a few possibilities but magnetic strength isn't sufficient for high power applications you may want to consider that a mechanical gear is inefficient due to friction yet a clean, dry gear set off a bicycle has been measured to 98% efficiency.

what sorts of equipment do you have? that's going to be the key factor. an rc copter needs to be built light, which is a problem when you talk rebuilt cars. the motor from a car is designed to be grunty. the motor in a helicopter is deisgned for weight, mid range power, and efficiency to cut battery weight. i think a basic design would be a fixed tilt rotor and vary the power to change the lift, the same for the tail rotor and a servo or something to swing a counter weight. you'll need to buy lighter motors and probably build from styrofoam.

iirc, you can't focus microwaves using parabolas in the size of the microwave chamber, the wave length is too big. you'd need a decent sized dish, metres across would do, then of course you have teh problem of the size of your focal point. you need power density, not just power. a standard microwave can put out about 700W. 200mJ in 10ns is 200 million watts. (that's why it's a pulsed laser with an incredibly fine focus) you can sustain a ball of plasma in a microwave with a piece of aluminium and a glass/pyrex fish bowl but i'm assuming you want something a little more refined

how fast does the gas need to come out? as far as i know, distillation is going to produce quite a bit of gas. also what are you distilling? the syringe can be taken a little further... dirtier too i built a vacuum pump out of a jam jar, 10ml syringe, a large bead and two check valves off a fish tank. it was put together with hot glue and the only problems i've had was water flash boiling in the syringe only to condense when it repressurised and the lid sealing too tight. (i did eventually fudge a relief valve) it's not the fastest to evacuate the chamber but mine gets to about 10Kpa from total vacuum.

it makes sense. a rock concert would probably break even. although i get what they mean by having to integrate it into the architecture, they'd want to concentrate motion to avoid wasting tiles.

try for a dc gererator head and a chunky inverter. an automotive engine isn't designed to run at a fixed rpm under variable load. ask the engine's manufacturer for an optimum efficiency curve (power/rpm) a servo throttle with a microcontroller ought to do it, all you'd need to look at is the rpm and the torque. you probably only need a tacho and an ammeter.

i'm not sure it's 20 anymore, i heard that asia is collaborating to make a commercial tokamac based on european tests

if nasa or some privateer makes space flight cheap and available to the public there's going to be a huge increase in interest. how many people who can throw cash around wouldn't go for a comercial stay at an inflatable hotel? the revenue from that sort of thing would probably go to either a snooty bilionare or funds for further space related tech.

the water level stays put unless you consider increasing density due to cold. the cube is less dense than water so some sticks out above the surface. it displaces it's mass in water. 1kg of ice displaces 1L of water and melts to occupy that same 1L.

it would work but there are a few problems with it. for the solenoid to work, you need the ship to have a decent amount of iron or other ferrous metal in it. now that's all well and good but on a space borne craft, mass is critical. most space craft are made mostly of aluminium or exotic metals to cut down on launch weight. a solenoid is also not likely to be entirely efficient, you'll have all sorts of inductive heating problems everywhere trying to fire up that much of a magnetic feild. nasa has come out with a relatively new approach to satellite insertion, perviously they either had to go to the satellite's orbital or mount a nice big rocket on the satellite, but now they've decided that a tether between the satellite and the shuttle can be used as a sling. you spin the whole shuttle and the satellite accelerates in a circular fassion on the end of a very long cable. then they simply let go and do a bit of their own course correction. a magnetic approach is plausible but a cable is more practical.

buckets are usually wider at the top than the bottom so the suction caused by drag should be greater at the top than the holes in the sides. i'd expect air to bubble into the water and the water to be sucked out the top. but no, the water won't move relative to the bucket if you can persuade physics to ignore the air.

you could use a vacuum flask full of hot water, they weigh less than the materials used to make them and can they retain a lot of heat. you could boil it at home and use it on location or modify the lid to utilise a pool heating type system, lots of black pipe and natural convection, (works both ways)

you only need an analougue system. if it's on course enough to spot the target it will course correct to hit the target. you need 4 suitable analogue detectors and a couple of transistors hardwired to the servo drivers. "smart bombs" travel hundreds of kilometres to a target they're only given a vague location for. this rocket is dropped from an RC plane in the right direction to a target that is a beacon. that's in the realm of amateur science.

air isn't very dense, but consider the pressure head of air above us. pulling a vacuum is displacing a 100km tall column of air. that's a lot. 100bar is one hell of an energy density if there's a compressible fluid. things get explosive quickly. 100bar puts almost 120 kilos on every square centimetre of exposed surface area.