Electric Airspeed Record.

[wst]

I wonder what scope this project entails. A full airframe build or "just" replacing tanks and engine with cells/capacitors and a motor controller?

If it's "just" a case of replacing an ICE powerplant with EV kit, might there be an option at some point to provide it for things like Red Bull air race? Those planes don't sound wonderful (that is the preserve of the crazy Reno racers with their highly non-standard Merlin/Griffin engines) so it wouldn't be much of a loss...

[Equus]

JuniorD said:

Is there a list of specific regulations or criteria for the record attempt?

Yes. As sanctioned by the FAI

[anonymous-user]

wst said:

I wonder what scope this project entails. A full airframe build or "just" replacing tanks and engine with cells/capacitors and a motor controller?

.

The airframe is a modified kit airframe: Nemesis_NXT

The only really rough "drawing" released so far shows the batteries mounted directly behind the motors in the nose of the aircraft. I'd imagine that there just isn't enough wing height (thanks to it's low aspect ratio) to get any batteries in the wings (where you really want them for structural reasons) and that a project to work out how to re-form factor batteries into a really thin form factor, and to make them able to flex as the wings bend would be extremely time consuming, risky and rather onerous!

Cruise speed is listed as 325 mph IAS when using a 350bhp LYCOMING engine. The power required for cruise speed is not listed, but the fuel consumption is listed as 20 gal/hr, vs 35 gal/hr at full power, so that suggests cruise power is around 60% of max power. 350 bhp x 0.60 x 0.747 = 156kW

The Yasa motors are listed as 70kW continuous each so 3 of them will definitely make at least 210kW,

The numbers listed for the std aircraft are probably not at MTOW, and this electric aircraft is going to be significantly heavier, so even with the same L/D there will be significantly more drag to overcome, however i'd be pretty confident this project can easily crack 300 mph continuously, and should be able to hit around 400 mph for short periods!

Edited by anonymous-user on Friday 11th January 18:27

[wst]

Max_Torque said:

The only really rough "drawing" released so far shows the batteries mounted directly behind the motors in the nose of the aircraft. I'd imagine that there just isn't enough wing height (thanks to it's low aspect ratio) to get any batteries in the wings (where you really want them for structural reasons) and that a project to work out how to re-form factor batteries into a really thin form factor, and to make them able to flex as the wings bend would be extremely time consuming, risky and rather onerous!

..


The numbers listed for the std aircraft are probably not at MTOW, and this electric aircraft is going to be significantly heavier, so even with the same L/D there will be significantly more drag to overcome, however i'd be pretty confident this project can easily crack 300 mph continuously, and should be able to hit around 400 mph for short periods!

I think the battery placement may also be a CofG consideration, which interestingly will not have to be taken into consideration as the flight progresses. I imagine the motors + controller are significantly lighter than the original engine (though I can't find the weight of the original engine to verify that, nowhere seems to note it).

And yes, it is probably just going to be a bit of a "muscle" job of getting the speed. It only has to go fast, not necessarily be super efficient about it or anything!

[Tony1963]

We need a competition similar to the Schneider trophy but for wiggly amp planes! And they’d probably spend a lot of time solving heat dissipation issues as those competitors did.

Would be a darned sight more interesting than Formula E, to this fascinated big kid.

[TheDrBrian]

wst said:

Max_Torque said:

The only really rough "drawing" released so far shows the batteries mounted directly behind the motors in the nose of the aircraft. I'd imagine that there just isn't enough wing height (thanks to it's low aspect ratio) to get any batteries in the wings (where you really want them for structural reasons) and that a project to work out how to re-form factor batteries into a really thin form factor, and to make them able to flex as the wings bend would be extremely time consuming, risky and rather onerous!

..


The numbers listed for the std aircraft are probably not at MTOW, and this electric aircraft is going to be significantly heavier, so even with the same L/D there will be significantly more drag to overcome, however i'd be pretty confident this project can easily crack 300 mph continuously, and should be able to hit around 400 mph for short periods!

I think the battery placement may also be a CofG consideration, which interestingly will not have to be taken into consideration as the flight progresses. I imagine the motors + controller are significantly lighter than the original engine (though I can't find the weight of the original engine to verify that, nowhere seems to note it).

And yes, it is probably just going to be a bit of a "muscle" job of getting the speed. It only has to go fast, not necessarily be super efficient about it or anything!

Lycoming put it at 270kg

[IforB]

Max_Torque said:

The airframe is a modified kit airframe: Nemesis_NXT

The only really rough "drawing" released so far shows the batteries mounted directly behind the motors in the nose of the aircraft. I'd imagine that there just isn't enough wing height (thanks to it's low aspect ratio) to get any batteries in the wings (where you really want them for structural reasons) and that a project to work out how to re-form factor batteries into a really thin form factor, and to make them able to flex as the wings bend would be extremely time consuming, risky and rather onerous!

Cruise speed is listed as 325 mph IAS when using a 350bhp LYCOMING engine. The power required for cruise speed is not listed, but the fuel consumption is listed as 20 gal/hr, vs 35 gal/hr at full power, so that suggests cruise power is around 60% of max power. 350 bhp x 0.60 x 0.747 = 156kW

The Yasa motors are listed as 70kW continuous each so 3 of them will definitely make at least 210kW,

The numbers listed for the std aircraft are probably not at MTOW, and this electric aircraft is going to be significantly heavier, so even with the same L/D there will be significantly more drag to overcome, however i'd be pretty confident this project can easily crack 300 mph continuously, and should be able to hit around 400 mph for short periods!

Edited by Max_Torque on Friday 11th January 18:27

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

Edited by IforB on Friday 11th January 23:22

Edited by IforB on Friday 11th January 23:55

[CanAm]

IforB said:

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

No, the Nemesis is a speed racer with a higher MTOW and smaller wing area than the Extra 300, and therefore more suited to the task in question, ie breaking a speed record. With its rearward cockpit location I would guess that its (relatively large) fuel tank is located pretty much on the CoG, so probably a good place for batteries too.

[AW111]

IforB said:

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

Edited by IforB on Friday 11th January 23:22

Edited by IforB on Friday 11th January 23:55

But surely since the force for the manoeuvre is generated by the wings, shifting mass into the wings should decrease the loading at the wing root.
Ideally you'd distribute the mass throughout the wing to match lift distribution.

A downside could be the negative loading of the wing root on landing due to increased wing weight.

[IforB]

CanAm said:

IforB said:

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

No, the Nemesis is a speed racer with a higher MTOW and smaller wing area than the Extra 300, and therefore more suited to the task in question, ie breaking a speed record. With its rearward cockpit location I would guess that its (relatively large) fuel tank is located pretty much on the CoG, so probably a good place for batteries too.

It may be a racer, but they pull some proper G around the towers. It might not be +10 -10, but at +6 -4 G then it is just as capable as many aircraft designed for Aeros.

The same principle stands. You do not want weight out from close to the CofG if you can avoid it. Centralising mass is a good idea when you are pushing things hard.

[IforB]

AW111 said:

IforB said:

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

Edited by IforB on Friday 11th January 23:22

Edited by IforB on Friday 11th January 23:55

But surely since the force for the manoeuvre is generated by the wings, shifting mass into the wings should decrease the loading at the wing root.
Ideally you'd distribute the mass throughout the wing to match lift distribution.

A downside could be the negative loading of the wing root on landing due to increased wing weight.

In an airliner wher manoeuvres are slow, then yes, this principle stands, but when throwing something around and making fast direction changes will create issues with inertia.

It’s not often you think about an aircraft in terms of handling and weight distribution rather than in engineering load path terms. In an airliner with FBW, then how it handles isn’t really an issue. It’s a bus and busses aren’t known for their abilities to turn corners.
Aerobatic aircraft need to take this into account.

For example, think about having fuel in tip tanks and getting into a spin. Is the fuel helping or hindering the recovery?

[Equus]

IforB said:

It may be a racer, but they pull some proper G around the towers.

It's not a pylon racer, either: its job is to make two straight passes, in opposite directions, through a measured distance. It can take as long as it likes (within reason and the rules - up to an hour, I believe) to turn around between those passes.

[IforB]

Equus said:

IforB said:

It may be a racer, but they pull some proper G around the towers.

It's not a pylon racer, either: its job is to make two straight passes, in opposite directions, through a measured distance. It can take as long as it likes (within reason and the rules - up to an hour, I believe) to turn around between those passes.

The Nemesis NXT airframe that is being used, is very much a pylon racer. As far as we know, the basic airframe structure is not being monkeyed with. Or we might do if the discussion on this thread was actually relevant to this aircraft rather than a load of waffle about electric airliners.

Here's a Nemesis going around a pylon...



If they were designing the airframe from scratch, then you may have a point, but they aren’t, they are using a known design and modifying the power plant. The wing is the same modified NACA NLA profile, which makes a lot of sense. They are hardly likely to then weaken the structure around the wing box deliberately, especially as this would cause issues with certification and massively increase cost and difficulty for no real benefit.

So, yes, fundamentally this is a pylon racer, just being repurposed with an electric power plant.

Edited by IforB on Saturday 12th January 11:23

Edited by IforB on Saturday 12th January 11:23

[CanAm]

IforB said:

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

I'm guessing that with the rate of roll of those Extras you'd want as much of the mass as possible concentrated around the CoG, to reduce the polar moment of inertia; hence no fuel in the wing tanks for aerobatics.

The Nemesis is a form of Pylon racer, and isn't subject to the same forces. But in THIS installation it's flying in a straight line so manoeuvrability isn't high on the requirement list. The old Supermarine S.5 and S.6 were pylon racers of a sort in their day and they carried fuel (and radiators!) in their floats.

[IforB]

CanAm said:

IforB said:

Errr. This is an aerobatic aircraft. Why on earth would you want the fuel tanks or batteries in the wings? This isn’t an airliner.

Think about the loads on the wing root in a high G manoeuvre. Would you really want the fuel tank on a long moment arm?

Take the extra 300 for example. It has wing tanks as well as body tanks, but specifically states that the wing tanks MUST be empty before aerobatic manoeuvres are performed.

I'm guessing that with the rate of roll of those Extras you'd want as much of the mass as possible concentrated around the CoG, to reduce the polar moment of inertia; hence no fuel in the wing tanks for aerobatics.

The Nemesis is a form of Pylon racer, and isn't subject to the same forces. But in THIS installation it's flying in a straight line so manoeuvrability isn't high on the requirement list. The old Supermarine S.5 and S.6 were pylon racers of a sort in their day and they carried fuel (and radiators!) in their floats.

Roll rate in an extra is startling and yes that is the primary reason for having wing tanks empty, but there are also the issues around how it handles on the limit in certain manouevres, so rather than just being a structural thing, it is very much a handling thing as well. You could get some very nasty characteristics creeping in.

Whilst a pylon racer isn’t an unlimited aero machine that spends much of its life flick rolling around the sky, the aircraft structure for the Nemesis is designed not to have any fuel tanks or weight in the wings. Adding batteries and therefore weight will change the loads onto the wing box.

As I’ve already said, if you were designing the thing from scratch and limiting it to straight line stuff only and low roll rates with a no Aeros limitation, that would change things about where the batteries are situated, but this is an aircraft designed to go fast anyway and go around corners tightly. All of which require fast roll rates and strength to cope with the G.

The old Supermarine aircraft were trucks in comparison to the Nemesis. It is tiny in comparison and weighs very little. That’s progress. It is able to better the speed of the S.6 but on a fraction of the power. The S.6 simply battered physics into submission through power! 1900hp doing 328mph vs 350hp doing over 400.

Anything doing over 400mph at low level and around the Reno course, is putting some serious stress on the airframe. The argument about this being simply a “straight line racer” and so not having to or being able to cope with big forces is just not right. These are massively strong aircraft and if the team started mucking around with the basic structure they’d be nuts.

The airframe is more than capable of giving them the performance they need. Their job is to sort out the propulsion.

[Equus]

IforB said:

These are massively strong aircraft and if the team started mucking around with the basic structure they’d be nuts.

Which is pretty much what MaxTorque was saying, when you tried to pick an argument with him.

[IforB]

Equus said:

IforB said:

These are massively strong aircraft and if the team started mucking around with the basic structure they’d be nuts.

Which is pretty much what MaxTorque was saying, when you tried to pick an argument with him.

No he stated that the best place for weight in an aircraft with this kind of performance is in the wing. I am just pointing out that it absolutely isn't. It is if you are designing an airliner, but this thing isn't an airliner. It's a pylon racer with an electric power plant designed to go fast and hard.

I am bringing the discussion back to what it should be about, this aircraft and the attempt on the speed record, not some nebulous and irrelevant nonsense about electric airliners.

[anonymous-user]

And once again this ^^^ demonstrates why this project is unfortunately fairly irrelevant when it comes to proving out future electric passenger plane technology!

What you want to do, what you can afford or have time to do, and what is actually best from a technical perspective is a compromise.

What we have here is an existing airframe, with the engine and tanks removed, and some batteries and a motors chucked into the gap they left......


For max range, which is the primary concern with any viable electric passenger plane, you need lowest drag. As the L/D ratio is (nominally) fixed for any given design point, lowest drag equals lowest mass. Lowest mass comes from the least amount of material, which means using construction materials with the highest specific strength, and designing the airframe with the lowest overall loadpath (ie total forces carried internally by the structure). In that respect, distributing the battery mass to match the actual pressure (lift) distribution of the airframe is sensible (ie most batteries in the wing).

With a large airliner, it's physical size actually provides sufficient wing thickness in which to put conventional batteries (how you deal with flexure and power distribution / cooling is a whole other matter!), with this single seat racer, i suspect the wings simply aren't thick enough across a wide enough area to even get any conventional (ie vertically oriented) batteries into the (limited) space available (access is effectively probably zero once the wing is built).

If they wanted to get the batteries in the wings,then the wing would have to be redesigned and the batteries would have to be redesigned. That would add a significant amount of risk / costs and resource drain into the project.

Given the Nemesis is stress to +6/-4 g, then all they have to do to cope with any additional mass in the fuselage is to drown rate the g limits ratio metrically to that additional mass. (and this project has no handling or maneuvering targets to meet as far as i can tell)

[Equus]

IforB said:

No he stated that the best place for weight in an aircraft with this kind of performance is in the wing. I am just pointing out that it absolutely isn't.

And AW111 has explained why MaxTorque is absolutely right, and you are absolutely wrong.

Even the most inept 1st Year Engineering student will be able to tell you that it's better to have a load distributed along a beam (which is effectively what the wing is performing as) rather than concentrated as a point load in the middle.

[CanAm]

IforB said:

The old Supermarine aircraft were trucks in comparison to the Nemesis. It is tiny in comparison and weighs very little. That’s progress. It is able to better the speed of the S.6 but on a fraction of the power. The S.6 simply battered physics into submission through power! 1900hp doing 328mph vs 350hp doing over 400.

But not bad for an aircraft of 90 years ago with a pair of bloody great floats underneath! The S.6b finally cracked the 400mph barrier too!

IforB said:

I am bringing the discussion back to what it should be about, this aircraft and the attempt on the speed record, not some nebulous and irrelevant nonsense about electric airliners.

Hear, hear!