Fun fact, there are databases of the exact frequency vs. time and it can be used to accurately time stamp audio/video recordings by correlating the ~50/60hz noise in the recording with the database. Good writeup on the technique and how it has been used in court cases: https://robertheaton.com/enf/
Ironically, this serves as an excellent refutation of the above analogy’s goal (to scoff at EMDrive experiments):
* Imagine telling a mechanic that mounting a ski box on your car with the fat/blunt end pointed forward seems to improve fuel economy vs being mounted the other way.
* The mechanic believes it’s absurd to claim you can improve fuel economy from a change that increases wind drag, so therefore your experiment is wrong since it seems to contradict established theory — case closed.
* Imagine that you more carefully measure, and find that it still seems to work surprisingly well (though also mysteriously reducing braking and cornering performance)!
* The mechanic still denies the result (which is unfair), and questions your test methodology and demands replications of the experiment (which is fair).
* Imagine someone else tries to replicate the experiment with a differently shaped ski box (i.e. not an airfoil, or with the airfoil shape vertically inverted), and fails to reproduce your results.
* The mechanic community concludes that the original result was obviously just experimental error, since the latter failure to replicate aligns with current theoretical consensus of what should happen.
In a similar way, early pioneers experimenting with winged aircraft design were laughed/scoffed at endlessly by established scientists/engineers of the era, ridiculed and crackpots wasting valuable time and resources.
The aerodynamics of the airfoil (which also explains the above ski box phenomenon) is an extremely non-obvious emergent effect, and even to this day is not as fully understood as most people probably assume.
Been following these guys for a while. Fascinating product.
To me though the most obvious but sadly simple use for this is sensor lights in damn toilets. Sit on the toilet for more than a few minutes in some places and the damn lights go out!
After a quick napkin calculation+google it seems the sun has around 20kW of power per square centimeter. So not entirely unfeasible that a cooler star, or a nuclear reactor is closer to the typical 10-100W/cm2 of a modern cpu/gpu. Still some orders of magnitude off from our closest star. (Hope calculation is correct)
Looking at the wikipedia page on red dwarf stars[1], it appears a small star (M9V) might have 8% of the sun's radius and 0.015% of its luminosity. Thus, it would have about 156 times less area, and 2.3% of the output per area of the sun. So taking your figure as given, that means it would be less than 500W / cm^2.
The temperature of the sun at its surface is ~5772 Kelvin. To get power per unit area, use Stefan-Boltzman: σ * T^4, σ * (5772 K)^4 ≈ 6294 W/cm^2. Dividing the sun's luminosity (power) by its surface area will also give a similar value.
A 815 mm^2, 250 W GPU will be 250 W / 8.15 cm^2 ≈ 31 W / cm^2.
The issue with the «chopping» is noise level. Counter rotating propellers are more efficient than a single propeller. «Contra-rotating propellers have been found to be between 6% and 16% more efficient than normal propellers.» https://en.m.wikipedia.org/wiki/Contra-rotating_propellers
“Simply put, unleaded fuel burns less smoothly than leaded and the toluene and benzene, which is added to the fuel to act as a lead substitute, burns to form what are called peroxides. Unfortunately peroxides are inherently unstable and explode, forming shock waves that cause detonation. This explains why engines designed to run on unleaded from the outset feature sophisticated knock sensors, which retard the ignition setting at the onset of harmful detonation.”
Right, but that article goes on to talk about various non-lead substitutes you should add... I know why unleaded vs leaded, but there are substitutes for lead that are designed for use in classic cars but don't actually contain lead, that's what I was asking the difference of.
Basically, why use actual lead in gas when lead substitute exists and is recommended for classic cars as an additive to unleaded fuel?
I believe that lead in petrol / gasoline still exists as there are not one but two effects from lead.
One is that lead helps promoting burning of the gasoline versus explosion or knocking.
Two is that lead is a great lubricant for the valve surfaces, preventing them eroding, leaking or sticking as they open / close. Eroding causes the engine to lose compression and efficiency, and sticking (as I have experienced first-hand) can cause a major engine failure by breaking the mechanism that opens/closes the valve.
This is correct, but it's also been overstated how important the lubricating properties of leaded gasoline were in these engines - while the harmful health effects were understated. [1]
I've found it varies by engine type. International Harvester light line SV engines for example definitely benefit from lead additives to fuel. Zinc additives in oil is another 'be kind to your engine' additive https://zddplus.com
Engines of previous eras were designed to leverage the 'lead' in gasoline as a lubricant and act as a 'cushion' to the valve seats and valves as the fuel flowed through the engine. Not adding a 'lead' substitute can damage your valves, and ethanol is to be avoided at all costs to protect the engine.
Engine 'knock' (multiple explosions on a single piston ignite cycle as different pockets of fuel mixture ignite) is also minimized by having 'lead' in the fuel.
Have '48 Chevy - can confirm that lead-substitute exists and classic cars will run with it. I never use the car without it so its possible the stuff doesn't actually do anything.
I suspect(and this is just my guess) that if you have a true classic that is worth millions of pounds, you don't want to risk running it on additives - so for those extremely rare occasions when you want to start the engine(car shows usually) you might as well run it on the £5/litre genuine leaded petrol.
