Russell McMahon
  • Member for 6 years, 11 months
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Is there a way by which one could determine the required temperature difference for stirling engine?
1 votes

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

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How high will a flywheel catapult launch a payload?
1 votes

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 ...

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Effects of Solar Shield on Electronics Enclosure
1 votes

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 ...

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What's a simple machine to lift and drop a 100 lbs weight repeatedly using an electric motor?
1 votes

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" ...

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Torque needed to draw back 220Lb's of weight?
2 votes

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 ...

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Could a string of large offshore wind towers support a Hyperloop tube?
2 votes

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, ...

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How to calculate the torque created by a rotating motor?
0 votes

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 ...

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How to calculate meters per pixel for a given camera?
Accepted answer
1 votes

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 ...

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Dc motors for controlling wheels of a wheelchair
1 votes

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 = ...

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How to accurately calculate the rpm from a gear train
Accepted answer
2 votes

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/...

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Wingspan formula for an Ornithopter
2 votes

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 ...

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How to simulate car acceleration
2 votes

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 ...

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Plastic Injection Moulding a Piece with Undercuts
1 votes

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 ...

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How does a frequency to voltage converter work?
2 votes

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 ...

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Control the rotation of multiple discs along the same axis
0 votes

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 ...

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Why do these memory spaces start at F8000 instead of F0000?
Accepted answer
3 votes

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 ...

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Wind protection for solar installation
1 votes

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 ...

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Is it possible that an electronic device "half-works" when the power adapter supplies too much voltage?
3 votes

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 ...

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Converting accelerating linear motion into constant rotational motion
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2 votes

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 ...

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Why design a cable stayed bridge with pylons inclined towards the obstacle being spanned?
4 votes

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 ...

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If my electronics are outdoors in a ventillated NEMA 4 enclosure, should I conformal coat my circuit boards?
4 votes

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, ...

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How does one go about building an underground structure without concrete?
7 votes

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 ...

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Is battery-charge-stop-at-XX-percent circuitry not cheap?
2 votes

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 ...

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How was it possible to beat a soldier with a full plate armor?
0 votes

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 ...

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Could future fusion energy exist without the input of any petroleum or natural gas products?
Accepted answer
5 votes

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 ...

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Can large capacitors allow power plants to run at full load and store excess electricity?
Accepted answer
6 votes

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! ...

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Calculate energy (kW, or kJ) from Vapour Expander Generator
2 votes

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 ...

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Vehicle emergency high-deceleration braking and steering system
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2 votes

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 ...

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What would happen if we tried to run a motor in space when it is not attached to anything to provide support to it?
Accepted answer
5 votes

Initially Assume an ideal motor with no mechanical losses and Operation in a perfect vacuum. Call the two portions rotor and stator - with all attached parts such as controller and power pack ...

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Is there current multiplier circuit?
3 votes

My input is DC from a small DC motor which I use as a generator. My input current is 300 milliamps and I need 1200 milliamps as output. Is there some way to increase the output to 1200 milliamps ?...

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