Engineering

A strange conundrum: nowadays whenever I try to play my Blu-ray edition of 'The Lord of the Rings', I get plenty of video, but no audio. That's to say there's audio throughout the preamble (adverts etc) that comes before the main feature starts. But as soon as the actual cinematic part of the disc begins it goes completely silent. The same problem exists on all three discs - though, interestingly enough, it doesn't occur on any of the special features discs bundled with the boxed edition. They come out loud and clear! No other Blu-ray film or DVD of mine has this weird and wonderful audio issue. They play just fine. It occurs only on the three LOTRs discs - and then it's …

A cool air turbine with a tubular duct that runs from its exhaust to its intake. Would the air speed in the duct be faster due to vacuum force rather than being open ended? Would the turning force on another inline turbine introduced into the duct system be greater or less? Would the air speed decrease after the added inline turbine to the duct system? This is not homework help its things that I have been thinking about due to a hobby project I been woking on but have no way of measuring air speed or turning force. I think it would increase airspeed and turning force on second turbine. I also think once the second turbine has spooled up too spee…

How do they make hydrogen tanks(I also need a oxygen tank, but I assume that it works the same way). If you blow hydrogen into a tank, how would you get the air out? With a gas tank, you're working with a liquid, and a gas, but for gaseous hydrogen, how would you push out the air, and put in hydrogen, without pushing out hydrogen in the tank? Also, how much volume would you need to fit 1 000 000 000 000 H2 or O2.

Hello dear friends! Heterojunctions are produced by deposition (often epitaxy) of a semiconductor on an other to achieve excellent components. Silicon being the most commmon material, Si1-xGex is used as a material with a different bandgap, despite the drawbacks of germanium: lattice constant very mismatched, main electron valley in <111> direction versus <100>... As opposed, the GaP crystal is known to resemble Si closely: same zincblende lattice (called diamond when the atoms are identical), lattice constants matched to 500ppm, main electron valley in <100> direction too. GaP's bandgap is also bigger and differs more from Si, nice. http://www.ioff…

Another (possibly silly) idea for a moonbase habitat, hopefully the last for a while: The latest ideas for moonbase as put forth by ESA is a 3D-printed shell made substantially of lunar regolith. https://www.space.com/19602-moon-colony-3d-printing-lunar-dirt.html Robots would be sent ahead of crew landing to build the base out of material sent from earth with in-situ resources. This seems ambitious to me on the how many things can go wrong front, though I admit it is very cool. So my idea is more pedestrian. In a previous thread I suggested using landed/crashed propellant tanks http://www.scienceforums.net/topic/110982-lithobraking-f…

What is the operating limit for which electronic devices work properly? In the US we see it is 60 Hz and in other parts of the world it is 50 Hz, so what are the upper and lower limits for which a device can operate properly?

How to cheaply and efficiently power a Moon Base. Powering a Lunar Moon Base isn't simple because the moon is in shadow for long periods of time. Solar power must have weeks of backup which would require a lot of batteries or some sort of backup generator that runs on maybe hydrogen and oxygen. Solar panels must be oriented to the sun to maximize efficiency, or more panels must be employed. One idea is to place the solar panels in space, perhaps at EML-1 and beam the power back to the moon. This still requires a very large array to capture the energy on the moon. This idea is similar, it uses a satellite in a polar orbit such that it is always exp…

A rotovator/lunavator with a 200 km long tether rotating in space above the lunar surface drops momentarily to swap a large battery pack (mass of 250 kg) for a depleted one to be charged. Is there a simple and effective mechanism that would do this? If the operation is too fast for a release then a catch, maybe two "bays" could be used. Instead of exchanging position on the tether on route, the base (where the exchange takes place) could coordinate which side or position is open when the exchange happens so that the spent battery can be placed at the correct location. Some king of catch and release mechanism - hook and eye? Ideally, an object in flight could als…

One year roundtrip, 30 day stay to Mars. Is it possible with solar thermal engines instead of nuclear thermal? https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140009587.pdf We can assume Earth and Mars capture orbits for the solar thermal part and chemical rocket to and from capture orbits. Perhaps with slower unmanned propellant drop missions ahead of mission if necessary.

It sounds really stupid at first - a survivable crash landing... The idea is similar to aerobraking where regolith is used to decelerate a space ship. Not one with humans aboard of course, it's a crash landing and bad things can happen. So bring the elliptic orbit of a ship to a grazing height and touch down, then skid along the lunar surface. But what can this get us? A bunch of otherwise useless upper stages of rockets could have their material recycled once dropped onto the lunar surface. If we do this enough times, we might become able to clear out a runway or learn how to do it without much damage, then more sensitive stuff could be "landed" this way. …

I'm working on a little project that involve hydraulics piston. I need an oil/fluid that is, 1. Density => water 2. Slippery 3. Non reactive 4. Easy to find 5. Cheap

hey i just one know if it is possible to make a motor of the size of the foot or even more smaller with the power of a motor of a car

Turbofans work by burning jet fuel to spin turbines, ultimately powering the massive fan you see in the front of the engine. Could you substitute the jet fuel with liquid hydrogen and, in theory, make a jet plane that produces no CO2

Are man made satellites called satellite before they are in orbit ...

Hi all, Im inventing a new product and need some advice as to what material i should use to create part of it. The goal is for it to be a clear material, thats heat resistant (wont bend or misshape) when a lit cigarette is touching it. Basically i just need to figure out what cheapest compound can be used as an ash tray almost. If i need to provide clearer instructions as to my request, just ask. Thanks!

Hi all. What to expect from electroplating a 'target' metal with two (or more) different 'donor' electrodes cyclically switched on for few seconds ? I do not have the equipment to experiment. Example... an iron 'target' electrode getting electrodeposition from both submerged copper and tin electrodes in the same vessel but only one timely connected (powered) at a time... With proper timing; would the iron be electroplated with bronze ? Or... several 'donors' creating a complex alloyed surface for corrosion/hardness/properties improvements ? Does such a practice exist in the industry ?

Hello you all! Astronauts going to Mars shall be protected from radiations. Since exotic shields look inconvenient now, and unless this one brings the necessary improvement http://www.scienceforums.net/topic/80982-shield-astronauts/ Nasa seeks to accelerate the manned transfers between both planets, something really hard with chemical propulsion. My Solar thermal engine enables that. http://www.scienceforums.net/topic/76627-solar-thermal-rocket/ For my Solar thermal engine, I use here Isp=1267s computed by tinkering Propep. The heavy mission uses D=10m concentrators to let each engine push 5.3N near Mars and if possible 12.4N near Earth - the launcher's fairing must acc…

Hello hitchhikers and tinkerers! Nasa wants now short trips to and from Mars for a manned mission to minimize the radiation dose on the crew since some shields have shown impractical. Also, I had wanted to lower the trip's perihelion to stay shortly on Mars, but with short leg durations, this looks compromised even with the Isp=1267s of my Solar thermal engine http://www.scienceforums.net/topic/76627-solar-thermal-rocket/ So here's my spreadsheet that estimates travel times and speed increments, without nearing to the Sun between the planets - this v5 lets orient the departure from the planet, and is bidirectional. NonHoMarsRadiusSlice5.zip Some speed increment example…

A bicycle, hanged off ground. Wheels turning. No or fixed steering, (or, both wheels on a rigid frame.) Trying/pushing to 'topple' it, some torques become active. If the wheels are turning in opposite directions, What torques/forces to expect trying to topple it? Next... wheels with their shafts at a right angle. What torques/forces to expect trying to topple it? Next... 3 spinning wheels with their shafts in the 3 axis. What torques/forces to expect trying to topple it?

Could a low-frequency EMP like a strong solar flare reach the bottom of the ocean where Internet cables would be laying? A specific scenario being that a large EMP reaches underwater Internet cables and fries Internet-related systems in Japan and America. And since that sounds like an oddly specific scenario I should mention again that this is for a sci-fi story. If large EMP’s can reach those cables, I am guessing that they would have to be laid wrapped in a flexible Faraday cage, and there would be frequent disruptions as sharks nibble at the cages (as they are known to do frequently with our cables now). Mr. Ask

Hi guys, i'm looking for a material that can withstand and reflect extremely high temperatures. These temperatures are along the lines of thousands of degrees Celsius, the kind of temperatures one would see if you measured the heat four to five inches away from a ball of hydrogen plasma, just wanted to know if anyone had any ideas on the subject

Some futurologist predicts that a vehicles may be designed to levitate on a plasma cushion: https://timeguide.wordpress.com/2014/10/10/the-future-of-levitation/ Does anyone can imagine how exactly it will work?

I am not a native speaker so I can't speak fluently. Please forgive me If I do something mistake here.

Which would you choose to make and why?

I think an "ideal" transport have to solve the following problems of the modern transport. It includes: 1) Be physically incapable to get in any kind of accidents. 2) Create no congestion. 3) Create no parking problem. 4) Create no pollution. 5) Be very fast. 6) Be flexible, desirably all-terrain and offer door-to-door delivery. I think most of this problems (with exception of the last one) can be solved (to a large extent) if people will switch to rail-bound personal transport. Something similar to this: http://www.eltis.org/discover/news/europes-first-urban-personal-rapid-transit-system-approved-poland-0 However, flexibi…