anchange

If I can find something that evaporates I might be able to only use packed sand around it instead of a ceramic coating that has to be fired/tempered. Could be quicker and more efficient.

It's not the negative mold that will actually pour metal into that I'm discussing. I'm talking about replacing the wax in wax lost casting with something else that evaporates.

0.1mmHg = .00013158 atm correct? Is that achievable for a 3ft by 3ft cube with some kind of simple box/vacuum that I put together? Seems like it isn't but I don't really know the scale of pressure.

Nice! Thanks John. Where can I find phase change graphs for these guys / what the sublimation pressure at room temp? Any idea how expensive menthol is in larger quanities say 20lbs or so?

Ha!! Thanks, that might actually work, not completely idea but obtainable. What about these parameters? 1. It will perform sublimation at a fairly easily attainable pressure and room temp (or close to it) 2. I can easily transition it from a solid state to a liquid state by adding or subtracting heat with in the range of -20 degrees C to 90 degrees C. 3. It's not toxic etc. I can work with it ok.

Hey everyone, I have a rather odd question. I'm trying to make a tricky kind of interior mold for metal casting and I’m wondering if there's an accessible element or compound that has these particular properties - 1. It will perform sublimation at a fairly easily attainable pressure and a temp less then 300 degrees C. Pressure will probably have to be below 1 atm but it has to be something that I can create without super fancy gear. 2. I can easily transition it from a solid state to a liquid state by adding or subtracting heat with in the range of -20 degrees C to 200 degrees C. 3. It's not toxic etc. I can work with it ok. Any ideas? I'm guessing sense I'm dealing with all three forms - solid,liquid,vaper the key is that the TP point be as close to atmospheric pressure as possible (while still under it) and also be as close to room temp as possible. But I'm not a chemist so you tell me Thanks in advance for the help!!! Bradley

Hey guys, I'm trying to figure out how the pulley system / gearing works on something like this - http://www.chapman-leonard.com/products/telescoping%20crane%20arms/15'%20Telescoping%20Hydrascope.htm Basically some kind of pulley system make the front 2 telescoping sleeve move in and out in unison as well as making the back counter weight slide to compensate for added or subtracted force on the front end. In addition the places that the camera is mounted stays level to the base as the crane is arced up or down. Any ideas? another picture - http://www.panavision.com/product_detail.php?imgid=158&id=110&cat=103&PHPSESSID=6kn8scjcplmgfn5i5nlnop1il6

I’m trying to design a larger Quadrotor (http://en.wikipedia.org/wiki/Quadrotor) craft that runs off of a single gas engine. Does anyone know anything about how quadrotors stabilize and how I would be able to achieve the same effects using a single gas engine for all 4 rotors? I assume it would have to be done through collective pitch adjustments? Is this even possible? Any help would be appreciated, thanks. Brad

I’m trying to design a larger Quadrotor (http://en.wikipedia.org/wiki/Quadrotor) craft that runs off of a single gas engine. Does anyone know anything about how quadrotors stabilize and how I would be able to achieve the same effects using a single gas engine for all 4 rotors? I assume it would have to be done through collective pitch adjustments? Is this even possible? Any help would be appreciated, thanks. Brad

Awesome forum… think I might be spending a lot of time here in the future. I’m a filmmaker by trade but I’ve always been interested in the science of flight… I got some free time this semester so I thought maybe I could do some reading. Anyone know some beginner books (or links) on the physics of flight? Things like calculating lift, wind resistance, etc Any help would be appreciated, thanks! Brad Paloaltothemovie.com