InigoMontoya

Why do you want stainless? In any control valve designs I've ever seen, the spring (if there is one) stays in a dry, protected environ. It never sees the process fluid or anything like that. Ergo, why stainless?

What is the application? I mean, a suitable stabilization device for a diving bell would be radically different than one for a hydroplane.

Sure. Go look for a leak on a dry steam system. It'll cut you to pieces. But range on something like that is going to be measured in inches.

Well yeah, but.... Potato guns *are* my hobby. I figure it takes a special kind of engineer to convince your employer to indulge you in your hobby.

Yes, it's a Firefly reference. I had to work hard for that acronym! The flash is the result of two things.... 1) Doubling of the kinetic energy. When the sabot hits the sabot stripper, some aluminum was vaporized. 2) The sabot was redesigned after the first shot and made to be much more... fragile. Yes, fragile is a good word.

A while back I made some references to a very large potato gun I was working on. At the time I believed I was OK to talk a little bit about it but it turned out my Is weren't dotted and my Ts weren't crossed. That is fixed now. And thus, I return to present to ya'll my favorite creation. VERA. It's a gun designed to study transonic impact but what makes it fun is that it really isn't anything more than a very carefully crafted potato gun... If your potatoes come from Chernobyl Farms, that is. Enjoy.

True, that's the point of plywood, but at least in my experience, it resists bending the best (ie, is strongest) in the axis perpendicular to the outer layer's grain. This being due to the strength contribution of any given layer being a function of the cube of the distance of that layer from the center of the sheet. In other words, strong in all directions does not equate to equally strong in all directions. True, one could counter this via proper selection of thickness for each layer, but my personal experience (read: observations that plywood is NOT equally strong in all directions) implies that the manufacturers do not do this (I'd guess for cost reasons). If you don't put enough matrix in the mix to fill all intersticial voids, your resistance to torsion or bending of any kind is complete and utter crap as the matrix cannot effectively transfer shear loads. If you put too much matrix in the mix, your tensile strength will be reduced.

Absolutely. Think of plywood. It's stronger in one direction than another, yes? It's not a perfect analogy to composite materials, but it's very close.

Just a thought but.... 1) Small stakes with corner reflectors mounted in a few very well defined locations in the field. 2) Periodically the robot sweeps a laser (mounted to a mast) in the direction(s) it expects to see the reflectors. 3) Based on what it "saw" when it did the sweep, it makes location corrections and continues on.

Well, it's not like you have to carry around a Nitrogen generator or a K bottle with you. You just need to have access to it so that you can refill in the event you system leaks. Shouldn't be any worse than recharging the air conditioner on your car right now. You've got a schrader valve coming out of your engine block. When you get your oil changed(*) for an extra $5 the guy checks the pressure and tops you off. Alternatively, they make small disposable gas bottles that can be filled with just about anything. The consumer is "used to" CO2 for paintball guns but they can be ordered with other gases in them. If such an engine were in mass production (it won't be for the other reasons listed), I imagine you'd be able to pick 'em up for a few bucks at any auto parts store. True such a bottle may not FILL your engine, but then, one quart of oil doesn't FILL the sump on your current vehicle. It just tops it off... Which is all that you'll need in the vast majority of situations. Pick your size (there are more, but you get the idea)... (*) Oil change probably not required for a Sterling. The point being "when you have some routine maintenance done."

Almost as an aside ('cause I'm not arguing anything else chilehed said) but... Nitrogen is damned near as cheap as air and eliminates the stated explosion hazard.

Short of using lasers and atomic clocks and other fancy schmancy equipment.... it wouldn't.

1.How will space mining be profitable when going into space is so costly ? It won't. 2. Putting people or payload in space is extremely costly And that's why. 3.How are they going to get in space go to China or Russia? ( NASA does not put people or payload in space any more ). The demise of the US Manned Space program has been greatly exaggerated. Hint: Dragon. While it may not be operational yet, it will have been in operation for years before any Moon Mining mission would be launching.

Can you provide a precise link regarding what you're talking about? A big of googling has yielded two types of link... 1) Plain ol' electric generators using permanent magnets. 2) "Free energy" hype about some mysterious device that isn't described in enough detail to shoot it down beyond "free energy is a violation of the 2nd law" but clearly that answer doesn't satisfy you. So what EXACTLY are you talking about? edit: And no, you can NEVER support perpetual motion without explaining why our current understanding of physics is inherently flawed.

I don't believe that they were inappropriate. Given the nature of the initial request it is pretty clear that we're almost certainly dealing with an entry-level physics student either at the HS senior or college freshman level. I'd wager that a sizable chunk if not an outright majority of such students get the ol' "what is the force of the car wreck" problem. I know I did in HS *and* in college. Assuming (yes, there's that word) that this is what we're dealing with, there is absolutely noting inappropriate about the time averaged approach. It is the only approach available given their educational experience and exactly the approach that the instructor is anticipating.

As much as I hate to get involved in a flame war, I find that I have to disagree with this statement. It depends heavily upon your industry. In mine (ordnance), such approximations are made all the damned time: A customer comes in and wants something done. You ask them for more detailed information. They don't have it. You ask for the time/money to study the problem in more depth. They don't have that either. You find yourself in a position where you have a job to do, but not the resources to "do it right." Result: You make assumptions and engineering approximations not so dissimilar to the one being discussed... And if you do a halfway decent job of it, you're rewarded very well; not fired.

I've no idea as to whether more or less power would be generated, but I strongly suspect that such construction would be very expensive and as such kW per dollar would drop.

As Xittenn implies, there are many ways to do it. I've done it once (as a college project). I've no idea if we modeled anybody else's "style" as the car pretty much designed itself once given the rolling chassis, and motor. Don't think in terms of copying somebody else. Think of terms of what makes sense for your application.

Another here who has spent many an hour on forklifts of various flavors including... rear drive, rear steering. front drive, rear steering. 4 wheel drive, 4 wheel steering (including crab capabilities). I also used drive my work vehicles in reverse a lot (long story). Rear steering is doable. I've done it with zero problems at speeds up to about 30 mph. It really isn't that hard to do but it is much more sensitive/responsive. If you're not used to it, you WILL oversteer and likely lose control. If you're used to it... No big deal; it just requires much finer control of the wheel.

OK. HS student. My apologies. I'll cut you a bit more slack. Pulling up the water even 100 feet up is no big deal. You attach a water pump to the end of a hose. You drag the hose in the water. The pump pushes the water up to your platform.

Any chance of providing a drawing or something? After reading your post I'm utterly confused as to what this all looks like. Mind you, I'm not heat transfer guy so I doubt I'll be able to answer it, but to have any chance at all I have to understand the question....

35 mph is nothing. Stick a tube down. Suck up water (assuming you're a hover craft and are close to the water). Do you have ANY training in ANY science at all?

When you're sitting on top of an ocean, water is trivial.

No need to claim cold fusion. That one gets chuckles from many in the scientific community. Meanwhile, plain ol' fusion (ie, utilizing HOT stuff) has never been done in a sustained, controlled manner by our civilization. Thus, any civilization that has a fusion power plant of ANY kind is significantly more advanced than we are.

BZZZZ!!!!! If you want to keep things as realistic as possible, you need to scrap the perpetual motion machine. You can't take water, split it into O2+H2, burn the H2, and get a net energy gain. It violates the 2nd Law of Thermodynamics. Let me put it this way: You say you're going to get your hydrogen via electrolysis. OK, great. Where are you getting your electricity? From burning Hydrogen? You've got yourself an endless loop here and such loops simply don't work. So.... Where are you getting your electricity from (and don't say "burning hydrogen)? 'Cause THAT is your power source. Your best bet is nuclear. Since this is such an advanced civilization, go for broke and claim fusion.