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Interesting Items...

Ezra Pound

Well-Known Member
I didn't really expect anyone to read the entire text, but if you had you would have spotted that the designer :-
would like to design an aircraft with no visible propulsion system or separate controls surfaces such as rudders and elevators.
So maybe he is addressing that as well
 
OP
Black Hole

Black Hole

May contain traces of nut
First aeroplane with no moving parts
This is mentioned in the current Electronics Weekly (which actually appears fortnightly... ish). Note the horse's mouth resolves the ambiguity introduced by the Guardian!:
Electronics Weekly 19/12/2018 said:
Engineers at MIT have flown a plane by what they have dubbed ‘solid-state flight’. Instead of propellers or some form of jet engine, the scheme uses high voltage to accelerate ions in the air, and these, in turn, accelerate the molecules in the air.

In this case, there are multiple accelerators – two columns of four rows.

Each accelerator consists of a horizontal wire in front of an aerofoil-shaped conductor (see diagram): +20kV on the wire and -20kV on the aerofoil causes nitrogen ions (yellow) to flow from wire to aerofoil.

As they travel, the ions drag gas molecules from the air (black) along with them. Though the ions stop at the negative electrodes, the molecules carry on – providing thrust.

In this case, the thrust was sufficient for sustained flight.

“This is the first-ever sustained flight of a plane with no moving parts in the propulsion system,” said MIT aeronautics researcher Steven Barrett. “This has potentially opened new and unexplored possibilities for aircraft which are quieter, mechanically simpler and do not emit combustion emissions.”

Haven’t we seen electro-dynamic ‘lifters’ hovering?

“For years, electroaerodynamic thrust has mostly been a hobbyist’s project, and designs have for the most part been limited to small, desktop lifters tethered to large voltage supplies that create just enough wind for a small craft to hover in the air,” according to MIT.

“It was largely assumed that it would be impossible to produce enough ionic wind to propel a larger aircraft over a sustained flight,” it added.

The work has been published in Nature as ‘Flight of an aeroplane with solid-state propulsion’.
 

EEPhil

Number 28
Re. aeroplanes with no moving parts. Whilst not strictly "no moving parts", did anyone else see a couple of episodes of one of those aeroplane disaster documentaries on one of the minor Freeview channels? In those cases all the control functions for the flaps, rudder etc. had failed and the pilot attempted to turn and land just by adjusting the throttle position on the engines. The reconstruction suggested the aeroplane was a sod to control but in at least one of the cases a safe landing was made.
 

Ezra Pound

Well-Known Member
Does your broadband connection allow 4K streaming or have you managed to download a 4K version?

EDIT

I couldn't get the latest beta version of Youtube-dl to download the vimeo video, however the Window version downloaded it :-

youtube-dl -f "hls-fastly_skyfire-20963" https://vimeo.com/226958858

I got a malformed AAC bitstream because ffmpeg wasn't installed, but the file played without it
 
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OP
Black Hole

Black Hole

May contain traces of nut
Does your broadband connection allow 4K streaming or have you managed to download a 4K version?
I was just looking at it in my iPad browser via the Vimeo site - the detail looked great with the Retina display, so I just assumed I was at some kind of hi-res (but I admit my broadband isn't up to normal 4K - maybe they are using very efficient compression or the content allows for high definition in a low bit rate).
 

Ezra Pound

Well-Known Member
It's available at 360, 560, 720, 1080 and 4K, ( I could only get 1080 in real time), but for some reason my Samsung TV on auto chose 360, which looked awful
 
OP
Black Hole

Black Hole

May contain traces of nut
IIRC, when I was at school a long time ago , one calorie was the amount of energy required to raise 1gm of water through 1 degree C (K).
Still is. Bear in mind the "calorie" referred to in food is actually a kilo-calorie.
Does this mean that a 'food calorie' would raise a litre of water through 1 degree C (K)?
Yes. You will see them described in the blurb on food packaging as "kcals".

2000 kcals consumption per day is about the same power as required to run a 100W light bulb.
And for completeness:
100 W for 24 hours = 24 x 60 x 60 x 100 = 8640000 J = 8640 kJ
2000 kCal = 4.186 x 1000 x 2000 = 8372000 J = 8372 kJ

4.186 being the specific heat capacity of water (and the conversion factor from Calories to Joules).
...and it is less fattening to drink cold water than warm water.

Does anybody know how "efficient" the human body is?

Energy in = energy out + energy stored​

Energy stored = additional fat + kinetic energy + potential energy​
Energy out = heat + noise etc​

Heat isn't necessarily "waste" - we need to keep our body temperature elevated over ambient so that the biochemical processes operate at a sufficient rate. However, I'm having trouble getting my head around what proportion of energy goes into actual mechanical effort without being dissipated as heat (I suspect not very much at all).

If you want to lose weight: turn the theromostat down and wear fewer clothes.
 

MikeSh

Well-Known Member
However, I'm having trouble getting my head around what proportion of energy goes into actual mechanical effort without being dissipated as heat (I suspect not very much at all).

If you want to lose weight: turn the theromostat down and wear fewer clothes.
Yes. It varies a bit with weight but jogging burns about 600 per hour and a doughnut is 400-500 calories.
Most people think that after 20 minutes jogging they've earned a doughnut :o_O:

Again it varies, but on average a person being largely sedentary but with some exercise doing normal activities needs about 2000 a day. Just keeping the body warm and operating is 1000-1500.
 

gomezz

Well-Known Member
Black Hole said:
we need to keep our body temperature elevated over ambient so that the biochemical processes operate at a sufficient rate.
I would be breaking out in a sweat if that was true regardless of the ambient temperature! :eek:
 
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