OT: Lithium ion battery developments

But they aren't likely to change the way they do that once EVs are common.

But that isnt going to CHANGE with fast chargers added.

There are some number here.

Don't forget that a lot of the things aircraft do don't apply to cars - such as choosing the ideal cruise height and speed for the weight of the aircraft, and changing it as the aircraft gets lighter.

I'm not convinced that composites are all that much of a good thing in the long term either. Aluminium is a lot easier to recycle than carbon-epoxy composite.

Andy

On BEV cars, the battery pack is pretty heavy, and the curb weight is pretty high for the BEV. On the other hand, with regenerative braking, some of the mass component is being neutralized a bit. (The power used to accelerate the mass, comes back during deceleration, with some losses in the process.)

Even if you made the mechanical framework out of pixey dust, it's still going to be a heavy car. The longer the range (and more expensive the battery pack), the more mass.

And this is used to alter the handling, because the mass of the battery pack is down low.

Paul

The offer a wide range for lifespan here, from ten to twenty years.

Paul

They are absolutely likely to do that once EVs are common.

What are their options?

The only politically viable solution is road tolls, and if the income comes from there it would be iniquitous to also get it from fuel duty.

Where?

but those are not really affected by any changes in engine 'efficiency' In reality long haul airliners fly quite close to 'coffin corner' slightly above stall speed and slightly below mach 1 at as high an altitude as they can because that reduces drag.

The engines are tuned for best overall efficiency in terms of jet exhaust velocity and bypass ratios in that regime.

not, its harder. you can turn carbon epoxy into plant food and water in any high temperature incinerator

Not with the TAX ON PETROL they arent.

None of that is the TAX ON PETROL.

The other politically viable solution is to pay for roads out of general taxation and avoid the need for the much more expensive collection of road usage data and charging that when you actually do the miles.

Not a problem if roads are paid for out of general taxation revenue.

A long way above stall speed actually.

and slightly below mach 1 at as high an

Just as motorway petrol doesn't come at supermarket price.

Ah, I've just listened to an "Inside Science" podcast where F1 engineer Paddy Lowe and friend are discussing manufacturing synthetic petrol from CO2 and hydrogen. I guess this is what you are referring to.

I wasn't entirely convinced that this was better than rapeseed oil, or bioethanol, but it is good someone is looking at it. Like hydrogen, synthetic fuel does offer a long term energy store for variable generation capacity. Time will tell how economic and scalable it is.

There are other more pressing problems with automotive battery supply than lithium. Here is quite a good deep dive:

Oops here...

That's not what is generally meant by recycling.

Andy

I tried and failed to find a reference for that.

Given that an airliner's stall speed clean is over 150kt (easily found) and the air pressure at cruising height is under a quarter that at sea level (also easily found) I would expect them to be fairly close.

Andy.

They arent, for a reason, FAR too dangerous.

In general an aircraft without flaps has around 2:1 ratio of top speed to stall speed. Extra power in military aircraft pushes that towards 3:1 as does heavy implementation of flats and slats etc.

Its hard to get one single figure for stall speed from e.g. an airliner as it depends on altitude, temperature, and aircraft weight as well as what flaps etc are deployed, nevertheless a 747 lands at around 160mph typically with all the gear out. One may conjecture therefore that without the flappy bits out it would be bear to its stall sped which gives a top speed of around 480 mph..at a 3:1 ratio

(Whether or not you could fly a 747 at 480mph at ground level I do not know)

Now

That is not a huge amount above the IAS stall speed without flaps of say

It's not the on the edge coffin corner that say a U2 used to fly at with the difference between speed of sound and stall speed not much over

In practice the designers do a lot of optimisation with one aim in mind

- minimising fuel and maximising income in terms of passenger miles and high operational utility. I,e, mist passenger miles per day, since interest on the capital cost of the aircraft accrues on a daily basis, not on how many miles it flies!

Well they are : from 150kt to 450kt at ground level, you are up to 250kt at say 40,000ft, and the speed of sound has come down.

its not hard to make a 2g turn and stall the thing.

It is if you need to pull a tight turn

WWII aircraft were in high speed stalls on tight dogfights at full throttle

It is not uncommon for an aircraft to pull 2g in clear air turbulence