OT: Plane fuel

[newshound]

I was going to say what about taking 100 tons up to 30,000 feet in 20 minutes, but that turns out to be 50 W/lb.

I stand corrected!

[The Natural Philosopher]

Oh. it has. USSR collapsed because of ideology.

Has.

Yes, but its not the one you think it is.

>

[The Natural Philosopher]

Its my little speciality - I did hundreds of model and full size plane calcs.

What is astonishing is how little energy it takes to keep a plane in cruise.

Its the glide angle times the speed in terms of watts per pound, essentially.

Which turns out to be glide angle in terms of watt hours per kg kilometer etc etc

For a slow flying model plane its about 1 W/lb or less. For an airliner at 300mph its a lot more of course - maybe as much as 50W/lb. But that's why airliners are built like enormous sailplanes...to get that glide angle down to the minimum.

(and why they have airbrakes and flaps - to ruin the glide angle to actually get the thing DOWN).

[The Natural Philosopher]

This got me thinking. Apparently a jumbo glides at 1:17 angle. At around

200mph.

So to keep it in the air at 200mpg you need to 'make up' 200/17 miles every hour

that gets to be about 19km every hour, or about 5.25 metres per second.

So neglecting engine inefficiencies Is that not about 51W/kg or around

20W/lb?

[dennis]

Compare that to a cruise ship!

[soup]

Anecdote:-

I remember on a (my one and only) commercial flight, sitting at a window seat being quite amused at the wing looking like it came to bits as the flaps, slats etc all deployed.

My ATC AEFs in a Chipmunk had nothing like the same effect and the parachute aircraft had high wings and I was too nervous to notice ANYTHING (apart from what I had been told to do).

[Jaffna Dog]

NUCLEAR POWER NO *TANKS*? Nuclear-powered tanks, how politically incorrect can you get! LOL! Although that Project Pluto has to be the ultimate non-PC weapon.

[harry]

Compare it to an electric car run off solar PV panels.

[harry]

You can go 99% of the journey to Australia by train. Visit Wodney. There's a thought.

[Tough Guy no. 1265]

But you have to go through the towel head countries.

[dennis]

Ok..

Lets assume you drive around during the day.. so there is zero solar energy used to charge the car.

So its charged from gas and coal power with about 10% nuke power.

No maybe not, lets assume its charged by those diesel generators being installed just to provide cover for when the sun don't shine and the wind drops. So that's about 15 miles to the gallon by the time all the loses have taken place.

Does anyone charge their electric cars during the day and run them about at night?

[The Natural Philosopher]

Only rent boys...

[Tough Guy no. 1265]

e

What about for plastics?

-- =

I have a photographic memory that was never developed.

[JHY]

Much of it never will be, most obviously when the carbon ends up in the atmosphere as CO2.

[Tough Guy no. 1265]

ge

Your writing style is identical to Rod Speed.

-- =

Reboot - to kick a computer in such a way that it turns off and then on = again.

[JHY]

That didn?t commit suicide, it changed to a better approach.

So did China.

Neither Russia nor China is an ex-society, they have just changed, just like they did from what they had before they were stupid enough to try communism for a while.

You have no idea what the reason I think it is.

[newshound]

What an astonishing concept! One has to admire the ingenuity of the man. I thought perhaps it was going to be something using pulverised fuel like a coal fired power station.

[newshound]

Havn't actually checked but it ties up with my back of envelope sum for climbing to cruise height. I normally use MathCAD for things like this because you can mix units completely at random, and even if it does not know a conversion that you need, you just define a new constant.

What amazes me about Dreamliners and the like is how slim the wings seem to be compared to the body. But I guess they are clever and get significant lift from the body as well.

[Nightjar]

I can't say that PC nuclear armageddon is a concept I have entertained before. :-)

[Nightjar]

I have a feeling that they also experimented with using coal suspended in liquid fuel in conventional jet engines.