Electric Airspeed Record.

[zombeh]

By electrifying an existing airframe to demonstrate how futuristic and shiny it is they've reduced the range by a factor of ~7. That's actually not that bad, if they can get than down to half that you'd have a useful aeroplane.

[fatbutt]

Max_Torque said:

fatbutt said:

https://jalopnik.com/rolls-royce-hired-formula-e-e...

The info graphic is interesting. Why use cells when packs from companies like XALT are a better packaged solution?

Edited by fatbutt on Sunday 6th January 22:54

i'd suggest 4 letters

C O S T


To make this project fly, it's looking like everything is as "off the shelf" as possible, hence the existing airframe, yasa motors, and pre-existing battery modules.

On problem becomes immediately apparent when you look at the data sheet for the yasa 750r motor

750R_datasheet

And that is the large derate, even at relatively low coolant temps for the motor. From around 200kW peak (at 750V) to just 70kW continuous. Datasheet shows between 90 and 92% efficiency at the propellers design point (2400rpm), so that's between 5.6 and 20 kW heat rejection per motor (@70kW 92% and 200kW 90% respectively), which is pretty trivial, which suggests to me that the cooling of that motor is pretty poor.

Ok, they ought to do a lot better than 60 degC inlet coolant temp (trade off with cooling drag obvs) so i'd imagine they'll squeeze a bit more than 70kW continuous out of it, but the motor is nothing to write home about really......

?! XALT are off the shelf, I used hundreds of them in 2017 on a prototype lifting device. Companies like Nissan and Renault use these style of packs in their cars. Cells was the Tesla approach simply because cells were the best tech available at the time and to get their production working they needed something easily available (so I've been told).

ETA: XALT only offered cells when we were doing our project but they do full modules now and BMS. By 'cells' I mean like AA batteries (as used by Tesla); the XALT units are flat units https://www.xaltenergy.com/cells/

Why are you concentrating on the motor? YASA are one of at least 5 axial flux motor suppliers and at least one (EMRAX) specialise in aircraft motors. YASA motors aren't the best but they are power dense when compared to others. We tried YASA in 2015 and found them a bit difficult to work with but I hear they have improved a lot since then.

The problem with all of the motor suppliers is that they quote kW output figures that they can achieve but they struggle to maintain, hence why you're finding so often a high peak quoted and a far lower continuous rating.

The key to any EV, including aircraft, is battery management. The motor could be one of a few different units with no great difference in performance (packing maybe).

I'd be interested to know what motor controller they've gone with. As its ex. Formula E is it the Mclaren unit? If it is I'd be surprised that they aren't using the electric motor and BMS from them too as getting the motor to work well with the controller and battery management system can be a pig of a dog of a nightmare.

There's a lot of negativity on this thread already and I really don't understand why. This project is an attempt to build something to perform a task, encourage others to do the same and maybe prove a point about what can be done with current tech. Its not a prototype for a future aircraft industry but who knows, maybe the child who sees this break a record will be the one who makes the breakthrough in 10 or 20 years time.

Edited by fatbutt on Monday 7th January 09:07

[IN51GHT]

Max_Torque said:

fatbutt said:

https://jalopnik.com/rolls-royce-hired-formula-e-e...

The info graphic is interesting. Why use cells when packs from companies like XALT are a better packaged solution?

Edited by fatbutt on Sunday 6th January 22:54

i'd suggest 4 letters

C O S T


To make this project fly, it's looking like everything is as "off the shelf" as possible, hence the existing airframe, yasa motors, and pre-existing battery modules.

We are actually developing our own modules.

[fatbutt]

IN51GHT said:

We are actually developing our own modules.

We did that too, it worked well in the end but I wish we'd have bought these instead (I didn't know of them at the time): https://www.emdrive-mobility.com/bms-s05 It wouldn't have been as space efficient as we wanted but if you offset that against the delays and general issues we had developing our own (almost burn the warehouse down!), I'd have revised the housings.

Have fun insulating all your tools Working anywhere near the battery pack use to scare the bejesus out of me.

I don't know about anyone else but I think the project is fascinating. Best of British to you!

[fatbutt]

Any idea on timescales? And is this a race i.e. do you have competition?

[AW111]

One niche that electricity is beginning to exploit is glider tugs. It's a very short duty cycle : climb to xxx feet, glide down, park. Although they're towing a glider, there's no payload required.

The benefits appear to be fuel and maintenance costs, along with less noise.
One advantage of electric drive is designing your engine to match the prop, without requiring a reduction drive.

[loudlashadjuster]

fatbutt said:

There's a lot of negativity on this thread already and I really don't understand why. This project is an attempt to build something to perform a task, encourage others to do the same and maybe prove a point about what can be done with current tech. Its not a prototype for a future aircraft industry but who knows, maybe the child who sees this break a record will be the one who makes the breakthrough in 10 or 20 years time.

Don't know if it's quite negativity, MT has said he acknowledges the drivers behind the project and in that respect it is worthwhile, but is simply trying to get across that almost nothing about the RR project will lead to a useful (as in 'able to do work') electric plane taking to the skies, now or in the future, so to pretend as much is naive at best, and downright 'Musk hyperloop' levels of delusional posturing at worst.

I defer to those with much greater knowledge in this field, but even my layman's understanding of the disciplines involved and back-of-fag packet calculations tells me this.

I too think the project is a worthwhile endeavour, but would ask people to remember at RR's own stated aims for this project (building a PR-friendly plane to break a world record and developing knowledge around the in-flight systems needed) and not get sucked into the 'OMG we'll all be flying to Lanzarote in all-electric planes within 5 years' type of reporting seen in some of the press.

[IforB]

Max_Torque said:

Storer said:

To say a project like the RR Electric plane is a waste of time is unfair and incorrect.

I have never said that, and i never will. The project will be a lot of fun, it will keep some clever engineers in a job, provide and interesting topic for learning for everyone, provide RR with many column inches and excellent PR. It may even inspire some young kids to become engineers.

All if that is very worthwhile!


BUT.

What it won't do is in any way change the viability (non viability) of battery electric passenger jets. That sort of greenwash doesn't help, as all it does is to set un-realistic expectations in the publics mind.

You forget a single word in all of this and that is yet.

All new technology has to start somewhere. We all know what the issues are with battery technology and energy density, but that doesn't mean it will be a problem for ever. RR are being smart here. They are looking at spending a fairly insignificant sum that nets them benefits in a few ways.
For a start, they get some actual knowledge from this. Will it change the design of current aircraft? Of course not. Will it affect the next generation of Public Transport aircraft? Probably not. Could it impact the generation after that? May be.
Next they get some good publicity.OK it may be a bit of Green washing, but so what? At least they are trying something new.

With my GA hat on, I'm very excited about the idea of a small, electric aircraft. The current things we're lumbered with rely on technology that even a Tyrannosaurus would find a bit old hat. GA has been in the dark ages and to survive needs to change.

I would love to have a couple of quiet little electric aircraft sitting on a grass strip that I could teach with. It would be ideal.

One other thing you forget is that this sort of project is very useful for solving the other issues, beyond the technical one, that we have in aviation, namely, how do you get a regulator to sign off on technology like this?
What is the certification process for the aircraft and associated systems? Working with EASA to develop a regulatory framework at this early stage and with a relatively simple aircraft will save vast amounts of time compared to doing it with a later and more complex aircraft that has technological capabilities in advance of this one.

So all in all, as a strategic development for RR and everyone else to be involved in, this is a fascinating project and your criticism of it and what the team are trying to achieve, seems somewhat high-handed and unfair.

[loudlashadjuster]

loudlashadjuster said:

...not get sucked into the 'OMG we'll all be flying to Lanzarote in all-electric planes within 5 years' type of reporting seen in some of the press.

Did not expect PH to be one of those outlets

PH article said:

Unless you've a close ear to the aviation industry, it might be hard to fathom that in only a decade or two we could see electrified planes take to the skies for short haul flights. Using pure - or, more likely at first, hybrid-electric power - they're set to drastically reduce emissions, noise and ticket prices, once the cost of production comes down.

Because of course, the cost of production is the only hurdle

[fatbutt]

loudlashadjuster said:

Because of course, the cost of production is the only hurdle

They do say 10 or 20 years. 20 years development will bring some serious changes in electrical tech. Compare now with '98 tech. In '98 don't you think the argument would be almost identical for electric cars (range, weight, etc.)?

https://www.youtube.com/watch?v=DCyLOWfIrCU roughly 40 secs in

[pingu393]

fatbutt said:

This project is an attempt to build something to perform a task, encourage others to do the same and maybe prove a point about what can be done with current tech. Its not a prototype for a future aircraft industry but who knows, maybe the child who sees this break a record will be the one who makes the breakthrough in 10 or 20 years time.

Bingo

This is how I see it. A great advert to future little engineers to see what could be done with 2018 technology.

[Talksteer]

Max_Torque said:

I don't want to sound a downer, on things, and this is clearly a fun little project, but it's not really pushing any useful boundaries? I mean, propeller aircraft can fly faster than 400mph (and have done so for nearly 90 years now (407.5mph in 1931)), the yasa motors are nothing special, the batteries, and nothnig special, the plane itself, whilst i'm sure it will be reasonably trick, isn't particularly novel as far as i can tell. And critically, it doesn't help electricfy air transport, because it doesn't solve the single stumbling block of insufficient energy density? So other than generate some nice column inches for RR, what does it achieve?

The person who starts developing an electric aircraft when the batteries are ready is the person who fails at commercialising electric aircraft.

The challenges addressed by this are:

Aircraft integration of the high electrical power components, how well do they package, what systems can be placed in what location.
Battery life in the aircraft environment
Certification - developing the operating experience of the components particularly the electric ones. How well do power electrical bearing, cooling systems handle aerial conditions.
Manufacturing,

It is the unknown unknowns that you will find out in this programme, you do this when the stakes are low rather than when you have actually sold a concept to a buyer and have a hard deadline and a fixed budget.

With electrification virtually every component and design practice on an aircraft is now up for grabs, unless you start actually building them you won't know what the hard challenges are and what the easily solved ones are.

The battery chemistries are being developed to support automotive, for early commercial applications this will be sufficient, once electric flight takes off serious money can be invested in aerospace requirements which are slightly different to automotive in the long term.

As I've been banging on about RR has already done the economic modelling, electric and electric hybrid flight effectively takes a bite out of intercity rail and long distance driving the market is massive particularly in developing countries which similar to how they skipped landline and went straight to mobile are also likely to fly more as they develop rather than build railways and roads.

We don't need to fly across oceans 200-300 miles of operational range is perfectly adequate.

[anonymous-user]

Talksteer said:

Aircraft integration of the high electrical power components, how well do they package, what systems can be placed in what location.

I think you'll find it's abit late to "learn" about high power electrics in aircraft, what with them having been used for years:




or

Talksteer said:

Battery life in the aircraft environment

787_battery_problems

Talksteer said:

Certification - developing the operating experience of the components particularly the electric ones. How well do power electrical bearing, cooling systems handle aerial conditions.

All those systems already exist in current airframes and are all already certififed

Talksteer said:

Manufacturing,

As far as i know, this speed project is to build a single, prototype airframe. That won't be anything to do with volume manufacturer or off-tools or off-processes either. It's some very clever people, in a nice shed, building a single, high speed aircraft using mostly off-the-shelf parts

Talksteer said:

With electrification virtually every component and design practice on an aircraft is now up for grabs, unless you start actually building them you won't know what the hard challenges are and what the easily solved ones are.

Commercial aircraft have been electrified for years. From engine starters, to fuel and hydraulic pumps, to control surface servo's to avionics, to air conditioning, and even to the TV fitted in front of each passenger so they can watch a movie (An A380 for example has 360 KVA of ground power interconnects, just to keep stuff running when it's sat at the gates with the engines off......)

Talksteer said:

We don't need to fly across oceans 200-300 miles of operational range is perfectly adequate.

Well i hope not, because the time i flew, a 300 mile range would have mean't i'd have to have walked the last 300 miles! ( and that was in Europe, let alone America or Asia etc)

[anonymous-user]

fatbutt said:

. 20 years development will bring some serious changes in electrical tech.

And you know this how? The last 20 years in EV passenger cars (and i've worked with EV cars for that long!) hasn't actually brought any great change, other than the COST per kWh falling with mass production. Even crap 'lecy motors are 90% efficient (super trick, mega expensive ones like the ones i have designed for F1, which cost the best part of £100,000 for the components for each motor, are up to 98% efficient. ie "just" 8% better. Same with batteries. The biggest improvements in battery energy density have actually been through the packaging of the cells and support systems, and not actually from the chemistry of those cells themselves. Energy densities have risen from something like 150 to 250 W. h/kg over the last 15 years, whilst to make an full scale, long range electric airline feasible, we need something around 5,000 W.h/kg......

(Kerosene is ~12,000 W.h/kg btw)

[zombeh]

IforB said:

With my GA hat on, I'm very excited about the idea of a small, electric aircraft. The current things we're lumbered with rely on technology that even a Tyrannosaurus would find a bit old hat. GA has been in the dark ages and to survive needs to change.

I would love to have a couple of quiet little electric aircraft sitting on a grass strip that I could teach with. It would be ideal.

Like this one? https://www.pipistrel.si/plane/alpha-electro/techn...

[Talksteer]

JonnyVTEC said:

Max_Torque said:

Ok, that's a big number, but each RR RB211 on the 747 develops a maximum of 258kN of thrust at an massflow of 728kg/s, which is a power of just about 45MW, and there's 4 of them fitted to that plane.

If we consider cruising at about 85% of peak thrust (fairly typical for a wide body jet), the engines would therefore be making 153MW, so the additional power from the solar panels could, at absolute best (assuming they have no effect on drag or mass) add an additional 1.3% range.....

I assume you mean peak thrust at altitude. Cos there’s no way you have anything like peak available take off thrust is at cruising altitude due to air density, nor do you need it to maintain flight.

Aircraft rarely take off at full thrust to reduce engine fatigue. Something an electric engine also might allow optimisation. I know I’m in danger of comparing passenger jet to a small prop aircraft doing that though.

Interesting project none the less! Even if for small island hopping or reconnaissance type exercises or stunt planes.

Probably engine up for UAV to take over wankel!?

Edited by JonnyVTEC on Saturday 5th January 23:23

There is a much simpler way of calculating required power of an electric propulsive system.

You know L/D for common aircraft types, this will tell you the drag force on the aircraft provided you know it's mass.

If you work on a combined electric, mechanical and propulsive efficiency of around 80-85% you will not be too far off in working out the energy/power requirements to fly a given range.

As regards range:

This is the clean air range (no account for any margins or climb or descent) in km of an electric aircraft for various battery energy densities and lift to drag ratios. I have assumed a battery mass fraction of 55% which is around the same as the max fuel fraction of a long range jet, given that batteries have structural value this may be pushed higher.

wh/kg	L/D=20	L/D=30	L/D=40
200	647	971	1293
250	808	1212	1616
300	970	1455	1940
400	1293	1940	2586
500	1616	2424	3233
1000	3233	4849	6465

We can manage L/D 30 with some nice high aspect ratio wings and clean design with relatively standard configurations. 250 wh/kg battery packs will be available by the time (2022) that the first limited production electric regional aircraft are entering service.

This means a practical range of about 900km or London to Berlin, this is enough to start the transition to electric flight.

If you want to fly further you can replace some of your battery space with a single gas turbine connected to a generator. Given that this will be a single design point, non safety critical gas turbine that only operates at one throttle position and only operates at altitude it may potentially never need to come off wing for overhaul and could be reasonably efficient and cheap.

L/D 40 and 450wh/kg batteries will allow you to do virtually any flight in Europe or China. This would require strut braced very high aspect ratio wings and possible laminar flow control on the airframe side and solid state batteries. Both are likely by 2030.

With 1000wh/kg batteries we could basically go anywhere, you would need to change more than today but that would be relatively painless if the batteries were changed or procedures were simplified. We could boost the range to ~ 9000 km by having a very high ratio of battery to plane. At current development rates batteries would hit 1000wh/kg in 20 years time.

[Talksteer]

Max_Torque said:

Talksteer said:

Aircraft integration of the high electrical power components, how well do they package, what systems can be placed in what location.

I think you'll find it's abit late to "learn" about high power electrics in aircraft, what with them having been used for years:




or

Talksteer said:

Battery life in the aircraft environment

787_battery_problems

Talksteer said:

Certification - developing the operating experience of the components particularly the electric ones. How well do power electrical bearing, cooling systems handle aerial conditions.

All those systems already exist in current airframes and are all already certififed

Talksteer said:

Manufacturing,

As far as i know, this speed project is to build a single, prototype airframe. That won't be anything to do with volume manufacturer or off-tools or off-processes either. It's some very clever people, in a nice shed, building a single, high speed aircraft using mostly off-the-shelf parts

Talksteer said:

With electrification virtually every component and design practice on an aircraft is now up for grabs, unless you start actually building them you won't know what the hard challenges are and what the easily solved ones are.

Commercial aircraft have been electrified for years. From engine starters, to fuel and hydraulic pumps, to control surface servo's to avionics, to air conditioning, and even to the TV fitted in front of each passenger so they can watch a movie (An A380 for example has 360 KVA of ground power interconnects, just to keep stuff running when it's sat at the gates with the engines off......)

Talksteer said:

We don't need to fly across oceans 200-300 miles of operational range is perfectly adequate.

Well i hope not, because the time i flew, a 300 mile range would have mean't i'd have to have walked the last 300 miles! ( and that was in Europe, let alone America or Asia etc)

I work at Rolls-Royce, not on this project but on other R&T activities, I have some visibility of the overall electrification project.

All the parts you describe are ancillary systems not megawatt scale motors and power electronics which must be optimised to much higher power to weight than for automotive applications. By and large these systems are also driving the mould line of the aircraft or taking up a significant proportion of its mass either which its propulsion system will be.

The RR electric flight project is much larger than this one project, but as I said before you have to start somewhere and if it was so simple it wouldn't be the most powerful and fastest electric aircraft yet built.

[GliderRider]

Max_Torque said:

GliderRider said:

There is a very big difference between modelling something on a computer and actually making it work for real

Interestingly, these days, there actually isn't. Modern computer aided design, simulation and modelling means like never before we can understand the critical design tradeoffs and make complex, multi-dimensional optimisations before any real hardware is made. Take the 777, designed way back in the early 1990s (so a dinosaur compared to todays "virtual" design resources) and yet the prototype airframe was actual sold and put into fleet service after it's development program!

Max_Torque, if only this were true.

I spent several years working on the 777 fuel system, running tests to determine why the FQIS (Fuel Quantity Indicating System) would suddenly show a zero fuel reading at the top of the climb (the pilots didn't like that...). We ran test rigs with all 60 fuel probes in fuel at different angles and different temperatures, I had fuel probes in tubes of fuel in which I could change the pressure to simulate the climb and observe the fuel de-gassing, we had probes in tanks of fuel on electromechanical shakers...

Do you know what the problem was? A simple flat bracket that Boeing provided to mount the fuel probes. It would vibrate as the engines were throttled back. This created a void in the fuel stillwell which would give a false fuel surface, and the system couldn't compute the fuel volume. These are the sorts of issues that a computer won't find as it can only work with the data its been given. Even if modelling had been shown to vibrate the bracket, who would have known that would create a void in the fuel? It certainly wasn't a phenomenon that I had seen before.

Just have a look at the mess Airbus got into with the A380, Toulouse were running Catia 5 and Hamburg Catia 4. The wiring harnesses did not match up. How many hundreds of millions did that take to put right?

Maybe the prototype 777 did get sold (no doubt at a massive discount) to a customer, but a lot of parts will have been replaced from when it first flew, and it is no doubt a lot heavier than a production airframe.

If computers were so wonderful, all these years that I have been earning a decent crust from qualification, certification and failure modes analysis work, I should have been on the dole, yet I wasn't.

[mcdjl]

GliderRider said:

Max_Torque said:

GliderRider said:

There is a very big difference between modelling something on a computer and actually making it work for real

Interestingly, these days, there actually isn't. Modern computer aided design, simulation and modelling means like never before we can understand the critical design tradeoffs and make complex, multi-dimensional optimisations before any real hardware is made. Take the 777, designed way back in the early 1990s (so a dinosaur compared to todays "virtual" design resources) and yet the prototype airframe was actual sold and put into fleet service after it's development program!

Max_Torque, if only this were true.

I spent several years working on the 777 fuel system, running tests to determine why the FQIS (Fuel Quantity Indicating System) would suddenly show a zero fuel reading at the top of the climb (the pilots didn't like that...). We ran test rigs with all 60 fuel probes in fuel at different angles and different temperatures, I had fuel probes in tubes of fuel in which I could change the pressure to simulate the climb and observe the fuel de-gassing, we had probes in tanks of fuel on electromechanical shakers...

Do you know what the problem was? A simple flat bracket that Boeing provided to mount the fuel probes. It would vibrate as the engines were throttled back. This created a void in the fuel stillwell which would give a false fuel surface, and the system couldn't compute the fuel volume. These are the sorts of issues that a computer won't find as it can only work with the data its been given. Even if modelling had been shown to vibrate the bracket, who would have known that would create a void in the fuel? It certainly wasn't a phenomenon that I had seen before.

Just have a look at the mess Airbus got into with the A380, Toulouse were running Catia 5 and Hamburg Catia 4. The wiring harnesses did not match up. How many hundreds of millions did that take to put right?

Maybe the prototype 777 did get sold (no doubt at a massive discount) to a customer, but a lot of parts will have been replaced from when it first flew, and it is no doubt a lot heavier than a production airframe.

If computers were so wonderful, all these years that I have been earning a decent crust from qualification, certification and failure modes analysis work, I should have been on the dole, yet I wasn't.

It would also result in the end of wind tunnel and crash testing. While there's no doubt conputer sims have come in a long way there's still a way to go.

[fatbutt]

Max_Torque said:

fatbutt said:

. 20 years development will bring some serious changes in electrical tech.

And you know this how? The last 20 years in EV passenger cars (and i've worked with EV cars for that long!) hasn't actually brought any great change, other than the COST per kWh falling with mass production. Even crap 'lecy motors are 90% efficient (super trick, mega expensive ones like the ones i have designed for F1, which cost the best part of £100,000 for the components for each motor, are up to 98% efficient. ie "just" 8% better. Same with batteries. The biggest improvements in battery energy density have actually been through the packaging of the cells and support systems, and not actually from the chemistry of those cells themselves. Energy densities have risen from something like 150 to 250 W. h/kg over the last 15 years, whilst to make an full scale, long range electric airline feasible, we need something around 5,000 W.h/kg......

(Kerosene is ~12,000 W.h/kg btw)

Oh for crying out loud! Battery tech has massively changed in the last 7 or 8 years and is making significant advances year on year as the motor industry digs its heels in on the R&D. The batteries I used only 2 years ago are outclassed by what I can buy today. Axial flux electric motors, the core component behind the current viability of EVs have only been viable since 2009. A 75kW standard electric motor weighs 500Kg, and equivalent axial flux motor weighs 10Kg. IGBT tech is drastically different in terms of size and communications; compare a '98 invertor (size of a cabinet) to a '18 invertor (size of a briefcase).

https://jalopnik.com/the-fascinating-engineering-b...

https://insideevs.com/nissan-leaf-40-kwh-battery-d...

Head of BMW i division:

“At the time of the BMW i3, the capacity of batteries was still quite low, and so we tried to get every kilogram out of the car to reduce the amount of energy we needed [to power it]...But, with the improving energy capacity of batteries, you don’t need to look for the last 500 grams. Therefore, we look for the right balance of properties. Carbon fiber is still an extremely important material when it comes to passenger safety, for example, but you only use it in certain areas.”

2018 tech will be hopeless when compared to 2038 tech.