Russell McMahon
• Member for 6 years, 11 months
• Last seen this week
• Auckland, New Zealand

$$\text{Absolute maximum efficiency} = \text{Carnot Efficiency} = \frac{T_{hot}-T_{cold}}{T_{hot}}$$ where all temperatures are expressed in degrees Kelvin (= degrees C + 273). A very well built and ...

As an upper limit - the maximum power transfer theorum says maximum power is transferred when energy in the flywheel and the mass are shared equally. Mass energy becomes 0.5 x m x v^2 and max height ...

Briefest start. Written from a hosp[ital bed just post operation :-) - better could follow if useful. Solar loading will be peak in hours around noon. Angles shift across year. Find your site 0n ...

100 lbm =~ 45 kgm. Wattage =~ kg x metres_vertical x 10 / time_seconds. So per metre of head, power = 450 Watts / seconds_to_lift. A battery electric drill (or even a mains drill) with a "drum" ...

I have a crossbow with - 220lb (100 kg) draw pull. - 12" (0.3m) draw distance - 1/2" (12.5 mm) ball lead screw - 12 to 24v DC high torque motor - guided by two linear slides. I ...

Could a string of large offshore wind towers support a Hyperloop tube? It's a well defined [tm] engineering problem well within the physical capabilities of available materials and methods, so, yes, ...

The arrows on your diagram are intended as a visualisation aid but, in this instance, you are better off without them. Torque is (effectively) conserved. Applying a torque impulse to a body "in free ...

Independent of what you are imaging, the ratio of object dimension to it's image dimension is a function of the lens focal length and the distance to the object. Knowing the sensor dimensions ...

What speed and Power must the dc motor provide to move a wheelchair at above specifications. Wheel RPM = chair_speed / Wheel-diameter x 60 Motor speed = wheel speed/Gear_ratio. Motor power = ...

Obtain a cheap plastic hand crank generator or several and play. That will show you much of what you need to know. If you turn the handle 1/8th turn (45 degrees) in 1/4 second then its RPM is 60/...

Wing loading: The graph below provides areas for living and man made flying machines - and this can be seen to be a quite good log-log fit of mass and wing loading. See his text for comment on the ...

Real-world torque at standstill: This is not your main area of concern but needs addressing so that you can then properly deal with the main issue. Your statement at t=0 acceleration is ...

I've worked on products designed by others which used injection moulding so while not an expert (and my terminology usage will be terrible) , do have a good feel for what may be attainable. I'd ...

As a general guide: One method is to provide a pulse of fixed width every time a slot passage occurs. The pulse widths are set such that at maximum pulse rate the output is either JUST 100% or ...

A diagram would help. A sliced cylinder suggests parallel disks on a common shaft. "Top and bottom" suggests a vertical axle - is it? Inner ones may also mean vertical. How many slices? Are they ...

Addresses are: A19 18 17 16 15 .... This expands on Dave Tweed's correct but brief comment: F8000 = 1111 1000 0000 0000 0000 <- A15 = 1 F0000 = 1111 0000 0000 0000 0000 <- A15 = 0 ...

Regulatory requirements will usually stipulate a mounting that will meet uplift conditions. Uplift is very approximately proportional to velocity-cubed normal to panel (eg under it facing up - so ...

Modern power adapters tend to be electronically regulated and not vary much in output voltage with load changes. Older ones that used iron core transformers were often less stable in output voltage ...

Do you really mean ACCELERATING linear to CONSTANT rotary motion? A variable ratio drive as in the DAF cone drive now used in a number of Japanese gearboxes would work. Provided the accelerating ...

As AndyT says - it seems it's aesthetics in most cases. Given the above as the answer, the following is essentially comment, but seemed worth posting as it gives a lot of detail of what goes into a ...

Requirements depend on environment,but, yes, conformal coating is, at a minimum, a really really good idea. Apart from condensation and misc stuff that manages to get in, ants can wreak havoc, ...

General: The assumption that concrete was not available is probably correct but not certain. The Colosseum is largely concrete and the Pantheon (still) has the largest unreinforced concrete dome in ...

IBM/Lenovo ThinkPad line is basically the only manufacturer/brand of mobility devices that includes circuitry and software that allows one to vastly prolong battery life of laptops used as stationary ...

History for centuries past always depends on who writes it, and the Engineering behind the history is thus somewhat a matter of conjecture, but: The English Longbow and "Clothyard shaft" are said by ...

The energy cost of obtaining Deuterium and Lithium is minimal compared to the energy released by the fusion process. There are many references that provide relevant information but a sensible one to ...

Capacitors are currently "rather too costly" for this purpose. I've revised my estimated cost after some more research but you appear to be in the 'well over one hundred thousand dollars" range! ...

Any engine that works at $50$ $^oC$ on the hot side is going to have a low efficiency. This may not matter but needs to be noted. The theoretical max possible $\eta$ (efficiency) is that defined ...

I gave this idea some thought some years ago -= catalysed by the events depicted in the video linked at the end. What you are describing is essentially a rocket. The concept is obviously possible as ...