What will power our vehicles in the future?

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#2944645 21-Jul-2022 09:39

Dingbatt:

Tinkerisk:

>> Nope, the slower it is, it has more time to burn energy to reach the destination.

This is ignoring thermodynamic law.

When talking about an aircraft Tinkerisk's statement can be very true. Not only will you burn fuel for longer, your fuel burn will be higher for longer, a double whammy.

It all depends as to where along the drag curve you are operating. Unlike a motor vehicle and aircraft has two types of drag. Form or shape drag and induced or lift dependant drag (drag created as a result of the wing creating lift).

Form drag increases as a square of increasing Indicated Airspeed just as drag does for a motor vehicle. Induced drag increases as an inverse square of reducing Indicated Airspeed. When these two drag forces are totaled you end up with an unsymmetrical V shaped curve which trends up more sharply below the minumum drag point than it does above the minimum drag point.

It takes a lot more power to fly slower than the min drag point than it does to fly above this point. In fact the speed where an aircraft get the most range for the fuel on board is higher than min drag.

Slower is not always better when it comes to fuel burn on an aircraft.

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Dingbatt

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#2944667 21-Jul-2022 10:48

Technofreak:

Dingbatt:

Tinkerisk:

>> Nope, the slower it is, it has more time to burn energy to reach the destination.

This is ignoring thermodynamic law.

When talking about an aircraft Tinkerisk's statement can be very true. Not only will you burn fuel for longer, your fuel burn will be higher for longer, a double whammy.

However in this case he is suggesting that burning fuel for longer (rather than considering fuel flow x time) will “use more energy”. The classic “drive home fast before your petrol runs out”. If you want to be pedantic about it then not only is there the aerodynamic considerations but also ancillary loads like bleed and generators where longer (in time) flights use more energy.

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mclean

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#2944686 21-Jul-2022 11:47

Scott3: Pure series hybrid cars are very rare, for the reason of efficiency. Only ones I can think of are the BMW i3 REX & Nissan note e-power.

And the new Qashqai e-Power, about to arrive in NZ.

Technofreak

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#2944747 21-Jul-2022 14:17

Dingbatt:

However in this case he is suggesting that burning fuel for longer (rather than considering fuel flow x time) will “use more energy”. The classic “drive home fast before your petrol runs out”. If you want to be pedantic about it then not only is there the aerodynamic considerations but also ancillary loads like bleed and generators where longer (in time) flights use more energy.

No not being pedantic, just trying to show you both can be correct depending on the circumstances.

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Technofreak

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#2944783 21-Jul-2022 14:28

One reason I posted the link to the BBC article was because of the last part of the article about what Airbus was doing, going down the hydrogen route.

https://www.bbc.com/news/business-62120130

In 2017, the company began developing a prototype hybrid plane, the E-Fan X, in partnership with Rolls-Royce and Siemens. Like Wright Electric's project, it was based on the existing Bae146.

But three years later, the programme was cancelled.........

....... In the short term, to reduce emissions, the company is focusing on using sustainable aviation fuels made from renewable sources and waste.

Beyond that, Airbus has its sights fixed firmly on using hydrogen to power a new generation of clean aircraft.

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#2944933 21-Jul-2022 18:21

Dingbatt:

However in this case he is suggesting that burning fuel for longer (rather than considering fuel flow x time) will “use more energy”. The classic “drive home fast before your petrol runs out”. If you want to be pedantic about it then not only is there the aerodynamic considerations but also ancillary loads like bleed and generators where longer (in time) flights use more energy.

More time to burn, not more burned energy - quite different.

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#2944938 21-Jul-2022 18:29

Dingbatt:

Tinkerisk:

In your dreams maybe.

Don‘t tell a pilot, experienced aircraft test engineer with MS degree in electronics who worked for decades for the A-Company about his dreams (or it’s projects in progress for the future). ;-)

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#2944979 21-Jul-2022 20:56

Okay. Deal😊

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Handle9

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#2944980 21-Jul-2022 20:58

Tinkerisk:
Dingbatt:

Tinkerisk:

In your dreams maybe.

Don‘t tell a pilot, experienced aircraft test engineer with MS degree in electronics who worked for decades for the A-Company about his dreams (or it’s projects in progress for the future). ;-)

We can still tell you though ;)

Tinkerisk

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#2944984 21-Jul-2022 21:25

Handle9: We can still tell you though ;)

Sure you can, as long as there is no audio function here ;-)

Technofreak

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#2963190 4-Sep-2022 21:47

The discussion is about Utes but the theme is about heavy vehicles and why BEV isn't a happening thing for heavy vehicles in the foreseeable future.

The point about the amount of energy require to carry the required energy is particularly relevant to aircraft.

https://youtu.be/qIlpHWo5uZo

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Scott3

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#2963211 5-Sep-2022 00:30

Technofreak:

The discussion is about Utes but the theme is about heavy vehicles and why BEV isn't a happening thing for heavy vehicles in the foreseeable future.

The point about the amount of energy require to carry the required energy is particularly relevant to aircraft.

https://youtu.be/qIlpHWo5uZo

For light road vehicle's there is a fairly quick and easy fix.

Move the 3500kg GVM threshold to 4250kg for pure EV's.

The light / heavy vehicle boundary is arbitrary anyway, and current petrol & diesel SUV's / Utes / Vans are already hitting up against the limit.

Nissan patrol: 3500kg

Ranger Wildtrak v6TT: 3350kg

Hiace van: 12 seat commuter: 3710kg (they only sell the 10 seater in NZ to keep it under 3500kg).

Once you add say the 477kg battery pack from the EV6 (74kWh useable) to any of these (less say 200kg of diesel stuff to remove), you are deeply cutting into the payload. Reality is most of these vehicles could do with 100kWh+ of usable battery due to their higher drag.

Reason I picked 4250kg is this is where the Uk has moved licencing limits to for EV's, so there will be plenty of 4250kg GVM vans that could be brought into NZ.

Should note that 4250kg is still less the epic 4,693kg (gross) of a Hummer EV, so that is off the menu.

For trucks carrying light stuff, like the one below, the weight of batteries isn't much of a big deal. NZ's first inter-city EV truck is on the road – SEA Electric

But for trucks like chemical tankers that max out on weight, adding hundreds of kg's of batteries comes straight off your payload, so hurts productivity. Can't really increase the weight limits, as we recently steeped up to 50MAX (tonne) where bridges allow, and those trucks are still restricted in where they can run.

On planes, We can make planes epicly heavy if we have epic runways to suit, but you are spending increasing amounts of energy to move the batteries around, and there will be a hard range limit based on the best available energy/weight batteries at the time.

I imagine the airline industry would be reluctance to use lithium polymer batteries due to safety reasons (the current choice for most drones due to their great energy/weight ratio, and fast discharge properties). Also they would need epic cycle life and fast charge (or swap ability) - Imagine if an airline had an epic extensive electric plane, they would want to run 10 Auckland - Wellington legs a day (ambitious, perhaps impossible I know), which at 50% depth of discharge, would clock up cira 1700 cycles a year. But the great cycle life of LiFePO4 batteries comes at the expense of energy density, which is bad for aviation.

Perhaps we will see a tech breakthrough like lithium–air batteries which will give us an order of magnitude better energy density than we have at the moment.

Sidestep

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#2963216 5-Sep-2022 05:24

Scott3:

Reason I picked 4250kg is this is where the UK has moved licencing limits to for EV's, so there will be plenty of 4250kg GVM vans that could be brought into NZ.

Yes 4250kg seems be be the new de-facto 'light duty' GVWR limit. If they're going to let UK spec (RHD) light commercial vehicles into NZ they'll have to make a move.
Vehicles like Ford's (UK) light-duty e-Transit models come in 3500, 3900 and 4250kg, the UK Mercedes e-Sprinter's are 3500kg etc.
The whole COF vs WOF, hubodometer exemption, compliancing etc would be a pain for what is, essentially an electric 'Class NA' light goods vehicle.

In North America it appears a similar 9500lbs (4300kg) 'light vehicle' GVWR is about to take the place of their combined previous Class 1 (max 2750kg) and 2a (3850kg) classifications.
Ford's got both their F150 'Lightning' "light-duty pickup" and lwb e-Transit "light commercial van" (just) under that limit.
The EISA rating of 'commercial' - Class 2b through 8 will likely now be above 9500lbs for zero-emission vehicles.

Apart from being Federal Highway Administration class-limits (in turn affecting manufacturers' emissions and fuel economy certifications) in quite a few States the classification affects both your licensing and Insurance costs.
In turn your taxes/depreciation schedules etc. are affected. The US Department of Transportation (DOT) - along with with the EPA was making noises about gross-weight/class changes back in 2015.

Similarly, over here the move to Battery-electric and Fuel-cell trucks has put the wind up RV manufacturer's groups.

At the moment a motorhome (eg Class A) - to be driven on a standard car driving license - must be under 26000lbs (11800kg) in most States and Provinces.
They're usually built on truck chassis (eg Ford or Freightliner). Following their estimations, with batteries you'll be looking at 15 tonnes for the same size RV.

That's a lot of weight for our elderly neighbour (who drives her motorhome to Arizona each winter) to be driving.
It'll also call for a massive upgrading of RV park's electrical systems. A hundred of those things fast-charging overnight will pull some amps.

And - an architect friend says engineering calculations for things like ramps and multi-level parkades are having to be altered due to increasing vehicle weights.

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#2963357 5-Sep-2022 09:48

Scott3:

On planes, We can make planes epicly heavy if we have epic runways to suit, but you are spending increasing amounts of energy to move the batteries around, and there will be a hard range limit based on the best available energy/weight batteries at the time.

I imagine the airline industry would be reluctance to use lithium polymer batteries due to safety reasons (the current choice for most drones due to their great energy/weight ratio, and fast discharge properties). Also they would need epic cycle life and fast charge (or swap ability) - Imagine if an airline had an epic extensive electric plane, they would want to run 10 Auckland - Wellington legs a day (ambitious, perhaps impossible I know), which at 50% depth of discharge, would clock up cira 1700 cycles a year. But the great cycle life of LiFePO4 batteries comes at the expense of energy density, which is bad for aviation.

I don't see a particular problem with LiPo batteries in aircraft. After all, avgas is perfectly acceptable despite its safety issues.

Thinking outside the box... how about a tow-car or winch or whatever that accelerates the aircraft along the runway, kindof like the catapult on aircraft carriers (but less violent, since you still have mile-long runways)? This would mean that you don't need to carry as much battery on the aircraft, and could potentially reduce the size of the motors since they're normally only needed at 100% power for takeoff.

Sidestep

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#2963410 5-Sep-2022 11:41

frankv:

Thinking outside the box... how about a tow-car or winch or whatever that accelerates the aircraft along the runway, kindof like the catapult on aircraft carriers (but less violent, since you still have mile-long runways)? This would mean that you don't need to carry as much battery on the aircraft, and could potentially reduce the size of the motors since they're normally only needed at 100% power for takeoff.

That's not really a new idea.
A winch, or glider type tow launch - to avoid fuel burn (or battery drawdown) - has been looked at by a number of companies, including Faradair mentioned earlier in this thread.

In the end Faradair decided an extremely light, powerful and quiet aircraft with boosted STOL capabilities would fill the niche they envisioned - a low altitude, short hop service.
A couple of years back I listened to a podcast where Faradair CEO Neil Cloughley discussed the reasoning behind this design - they've certainly advanced it a lot since then.
The engineering's there, with some big names and serious players involved.

Neil was right in his predictions - the technical requirements of medium and long-haul aircraft (weight, seat capacity, speed and range requirements) still can't be met with current battery technology.

But - as you noted, taking off - climbing to altitude's where a lot of the energy's required.
They get the launch and climb out taken care of using a hybrid-electric aircraft with basically a one-time (before it recharges again from the turbo-generator) battery powered STOL boost.

The turbogenerator provides power to the motor(s) in parallel with batteries when high thrust is needed, or alone, slowly recharging the batteries when low thrust is needed such as during cruise.
This enables overall downsizing of turbo-engines and increased fuel economy.

Their prototype combines Honeywell’s existing, flight-proven Honeywell HTS900 engine with two compact electric generators capable of providing about 200 kilowatts together.
And Honeywell's developing their near-term system, a 1-Megawatt generator combined with the company's HGT1700 auxiliary power unit, currently flown on every Airbus A350 XWB.

The reality of very high-altitude, composite, tow launched, atmospheric wave riding - passenger carrying - sailplanes is probably beyond my lifetime (though - as someone who used to fly gliders - I'd love to see it).
This is something we might see next year.

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