ironizer

OK, so explain exactly why the heat cannot be made into work.That's what i'm not getting.

yeah but I read that even the carnot engine (which i think is different than what i described) can't be 100% efficient. Got this on wikipedia A third formulation of the second law, the heat engine formulation, by Lord Kelvin, is: It is impossible to convert heat completely into work. I think that is because at the peak of expansion, the volume of the gas is greater than what it is when it starts, which means that there is heat trapped inside that cannot do work. The thing I'm thinking about, is what if there is no outside pressure, and instead there is a vaccum. Then the piston can expand infinitely, creating an asymptote that nears 100%. Carnot efficiency equation is [math]\eta=\frac{\Delta W}{\Delta Q_H}=1-\frac{T_C}{T_H} [/math] I don't see how the temperatures affect the efficiency. Shouldn't it be the pressure outside/pressure inside ratio?

The fact (or is it?) that a heat engine will never attain 100% efficiency in transferring heat into work, even under ideal conditions, really annoys me. Imagine this: A cylinder-piston arrangement is made out of a material that is non-thermal conducting, and there is no friction or air resistance between the piston and the air/walls. Now suppose that the cylinder contains a pocket of air that is at the same pressure as the air outside. The pocket of air is quickly heated by an external source so that the temperature in the pocket rises, thus increasing the pressure. This pressure difference will cause the piston to accelerate outwards, expanding the volume inside the cylinder until it cools and reaches outside pressure again; at that point the kinetic energy of the piston is promptly absorbed and turned into work. Given the above scenario, wouldn't 100% of the heat energy put into the system be transfered into work?

Dude, to build an enclosed pool that covers several square miles is about as impractical as hauling hydrogen from jupiter. Not only it will cost billions of dollars, it will also require vast amounts of fossil fuels to build. No free lunch, sorry.

I know, but this guy says that the piston that takes the explosion does not directly connect to a crank. Instead, its kinetic energy is used to compress a gas, which then.... goes where?

I just found out about this; http://peswiki.com/index.php/Directory:Gun_Engine Does anyone know how this think actually works? Anyone have any more info? I can't figure out how it uses the detonation to produce work. Otto engines use the pistons, but what does this thing use?

shucks... I was hoping that the X power would be high enough to handle extra load.

ok, another question. I have this R/C Car circuit board and I want to add another motor on there for extra power. I will also hook up another battery in parallel (for extra juice).Can the board be damaged by the extra power surge from the other motor? Thanks for helping!

I got an image for you... ... ok, so If I switch the switch ON, then would the electron flow on the red wire that goes to Load 1 have any change at all? Will Load 1 experience ANY difference if I switch the switch ON/OFF?

Dude... :eek: :eek: :eek: How many hours does it take to solve that stuff? My algebra sucks, I make stupid mistakes all the time. In an equation like that, I'm almost guaranteed to mess up. Just want to know if I should bail out of engineering and get a psychology degree for crying out loud.

I'm at the end of high school, and I want to pursue engineering, maybe mechanical or *maybe* aerospace/aeronautics. I have heard that they physics isn't that hard, but the math is HECK OF. I heard that some equations are like LONG @$$, like 12 foot long when the professor writes them on the board. I need to look at some real examples of this kind of stuff, see if it freaks me out. Anyone how has some equations that sound like that, paste 'em in. I'm not the math whiz kind of person, I can understand anything we're doing in math class, maybe not the first time around, but when I do a couple of problems I get the hang pretty quickly. Any suggestions also appreciated. Thanks.

I found this applet on airfoils and other types of lift methods: http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html seems like it is all based on the angle of attack and the curvature of the wing. BUT... I want to make one with the most possible lift and the least possible drag. Which shape is the best? If you can do it on the applet, give me the values or a screenshot so I can reproduce it. Thanxo!!!!

the advantage of capacitors is that they charge very fast. Those ufo things http://www.raidentech.com/rcufo.html have capacitors too, as well as the mini RC cars. Batteries have a limit on how fast they charge because they are chemical based. Capacitors also have a long life, something like 1/2 million cycles and you can pull them out from everywhere. I was thinking of making a semi-conductor pad so that when I want to recharge, I can just trow my heli on there and wait a few seconds. I also have some lithium-ion cells from a laptop battery. They are a lot longer and a bit wider than AA batteries, but are surprisingly light. They also give quite a kick, so I might use those. The only thing I am afraid of is that I can't get enough lift from a motor, so I might end up making a plane. Does an airplane require less thrust to stay in air as opposed to a helicopter? thanks!

I want to build a home made electric RC Heli, very small and light. I have one of those Mini RC racers, like these and i want to convert one into a heli. They are powered by capacitors, but I don't know If the motor and all can produce much thrust. I can make prop blades out of nylon to keep it light. Does anyone have any suggestions, ideas, or even better; has anyone actually made their own electric micro heli? If it won't work to make it out of the car, what can I use? I want to use capacitors, because Li-Po batterie cost too much. What motor should I use, etc. Thanks for any advice.

I have vaguely read from some crappy sources that some Gas Turbine Engines have multiple chambers. I tried searching all over the place for this stuff, but the whole freaking internet has nothing on it. If ANYONE has any bit of information on the design/how they work/non-vague diagrams/ ~anything~, please tell. This stuff is really really really really really really really really really really important to me. Help is very very very very very very much appreciated. Thanks thanks a lot lot!!!!!! !!!!!!

I was thinking of the "string cheese theory" it was mentioned in one of Brian Regan's comedy things... heck of funny, should watch it.

DC motors don't have many parts douching each other. If you get a magnetic bearing, the only thing you will hear is air getting pushed around. AC motors have brushes, and those make hella noise/sparks and what not.

given the info you gave me (thanks) and what wikipedia says: Centrifugal compressors — use a vaned rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser (divergent duct) section converts the velocity energy to pressure energy. These are for continuous, heavy industrial uses and are usually stationary. Their application can be from 100 hp (75 kW) to thousands of horsepower. With multiple staging, they can achieve extremely high output pressures greater than 10,000 lbf/in² (69 MPa). ... i came up with this design: http://img184.imageshack.us/img184/9850/designjh4.jpg tell me what you think. thanks a ton!

Thanks man, you don't know how much this means to me... but aren't piston compressors like.. really unefficient, because here i'm shooting for the highest effieciency possible, and i think turbines (just like any steam/water/gas/whatever turbines) are more efficient than pistons.

is it efficient in transforming the airflow into rotary motion, or is it the other side, the comrpessor, that sucks? ...because if that's the case, you can just use a centrifugal compressor for it, because those can get some serious pressures if used in multi-staging (that's what wikipedia says) if it's the other part (the one that takes in the exaust flow) that sucks, then couldn't you use muli-staging for that? What i'm trying to use this for is to take any airflow, and use it to compress air into another tank. It sounds retarded, but that's just how it is.

thanks a ton man... if you could give me an idea on this that would be so sweet, because I don't know anything about this stuff, and I REALLY REALLY need to know. muchas gracias!

hey, i think you're getting on the right track. I guess I didn't explain myself right using words, so this picture should help. I should have done this from the beginning. I don't want any exact math, I'm clueless to how efficient these are. Is it 25%? 30%? 50%? 75...80%? image at imageshack: http://img54.imageshack.us/my.php?image=turbopartskw3.gif

I don't want any math or anything, just need an idea of how efficient those things are, that's it. I realize the question was too complex for some of you (no offense) I'll put it this way: You feed the turbo a flow of air, and, on the other side, you get another flow of air OUT. My question is, if you put in 100UNITS of air in, then how many UNITS of air would you ~apporximately~, ~roughly~ get out on the other end? Don't try to get too complicated on this...

all right, so first of all, if you're reading this thread, thank-you, you're really cool, and even better if you can help... ok, so let's say we got ourselves a turbocharger thing, such as the one in the picture here: http://en.wikipedia.org/wiki/Turbocharger I wanna (really bad) know the efficiency of one of these (doesn't have to be the same type as the wikipedia picture one). You can think of it this way: You put 100KW of energy into compressing air. You pipe the air to the inlet part of the turbocharger, so that it works... compressing air into another tank. Given that everything in the system (except the turbo itself) is ideally (100%) efficient, (so no friction or nothing), then how much air would you get back into the second tank... or, if you used that air to generate electricity (again, generator and all that crap 100% efficient), how many KW could you pump out of it? Would be cool if you could hit me with some %-ege. I tired google but didn't work for me. Maybe my googling skills just blow @$$, i dunnno... Thanks if you can help!

ok, let's say you have a 1" magnet, with a pulling force of 2lb then you have the exact magnet, only it's cut in half, so you have 2x .5" pieces, each having 1lb pulling power (since they are half as long) then, if you take the 2 .5" magnets and stick them together to make a 1" magnet, will it have the same power as the original 1" non-cut one, or will it be less?