Electric Airspeed Record.

[anonymous-user]

Talksteer said:

I'm not going to go into details as to how I'd make it VTOL.

Fair enough.

Talksteer said:

As to your point, you come at electric as essentially a worse jet fuel.

It isn't, it allows you to do things that you couldn't with gas turbines and reciprocating engines.

Most basic example is the multi-rotor drone (now produced in greater total numbers than all other flying vehicles in history combined) which has allowed aircraft to be produced at costs and capabilities utterly impossible with liquid fuelled engines.

A multi-rotor is optimised for lift, but it does not use a "fixed wing" to create that lift. As such it has a really pretty poor L/D (typically less than ~5). That's fine for hovering, and low speed maneuvering, but hopeless for getting across oceans. It's easy to see this, just cut power to your drone at max speed, and see how far it glides for. (i think "flies like a brick" is probably actually a better description ;-)

I'm afraid i also fail to see how being able to make lots of small plastic "hobby" drones has significant impact on the costs of a full scale, fully certified passenger aircraft. The fundamental enabler for small drones is actually the high bandwidth of the rotor speed (and hence lift) control. Unlike an ICE engine (or worse still a jet engine) an electric motor can have it's torque modulated thousands of times a second, which has allowed the development of ultra fast "assisted" stability and control architectures. It's also worth noting that batteries scale reasonably linearly, unlike liquid fuel energy stores, which scale as a result of their surface area to volume ratio (ie bigger = better)

Talksteer said:

The F35B's L/D ratio is around 1/3 of what is possible, so your battery is now 8 tonnes.

I'm not sure it's that bad. It's dfifficult to find a best case figure for a "clean" F35B, but it looks to be around 14 to 15 at worst. 3 times that would be and L/D of 45, or about the same as a small, un-powered glider. I'm going to suggest that with current tech, that is far from possible.

Talksteer said:

Seriously stop using it as an example, it's like designing an electric car and asking where the gun turret goes.

If you don't want me to use the only VTOL supersonic aircraft as an example to show that you were making un-realistic assumptions, then i respectfully suggest that you perhaps should have not actually been the one to glibly suggest it in the first place! ;-)

[dvs_dave]

Storer said:

Now I’m not an engineer but a pure layman. However, I have a question!

I was under the impression that most ICE take their fuel and turn it into 3 things of roughly equal parts. Power, Heat and Sound.
I have no idea if this is true of a jet engine, but I asume it is not far off.

In that case comparing the energy density of kerosene and a battery needs to take this into account. Sure the electric motor will make a small amount of noise and a slightly greater amount of heat (plus some heating of the battery system), but surely not as much as 2/3 of the energy.

This said, is this being factored into the calculations being bandied about by others above?

This is a very good point that has been confusingly ignored so far. It needs further emphasis and exploration.

Only around 1/3 of the total energy contained in jet fuel actually makes it out as pure propulsion, the only thing you actually want. The propulsive efficiency of a jet engine system is nowhere near what an electric propulsion system could achieve. I’d imagine that an electric propulsion system could easily be getting on for a propulsive efficiency of around 80%. So that means approximately only 40% of the onboard energy storage is actually required to achieve the same result.

[Mabbs9]

I'm intrigued at the suggestion on the previous page. Any more ideas on how an airborne battery swap may be achieved?

[Mave]

dvs_dave said:

This is a very good point that has been confusingly ignored so far. It needs further emphasis and exploration.

Only around 1/3 of the total energy contained in jet fuel actually makes it out as pure propulsion, the only thing you actually want. The propulsive efficiency of a jet engine system is nowhere near what an electric propulsion system could achieve. I’d imagine that an electric propulsion system could easily be getting on for a propulsive efficiency of around 80%. So that means approximately only 40% of the onboard energy storage is actually required to achieve the same result.

The propulsive efficiency of a jet engine system is nothing to do with the prime mover - it's to do with making thrust by moving air. A particular propellor system for example would have the same propulsive efficiency whether it was powered by a turbochaft, a piston engine, or a wankel.

[AW111]

(Copied and expanded from the other thread)

I can't see electric long-haul transport in the foreseeable future : energy density being the critical problem.

However, there are enough short-haul and recreational uses to make electric flight commercially viable, and I expect to see more in the near future.
An electric 4-seater with 300 km range and a cruising speed of 200 kph would sell if priced right, and that's not a million miles from this RR project.



Can we just agree that electricity replacing hydrocarbons for long-haul flight is not feasible in the near future, and look at where electric power is possibly viable?

One reason GA (General Aviation) is a likely target is because they are still using 50's engine technology - eg magneto ignition and caburettor on an air-cooled flat six.

IMO this is largely due to :

A very risk-averse regulatory environment, particularly in the US, so getting new designs approved is complex, time-consuming, and expensive.

A very litigious US (the major GA market) where manufacturers can and have been sued for user error.

And the fact that these types of aircraft are propeller limited - to use a modern, high revving automotive style engine requires a reduction gearbox, which is (relatively) heavy, and another critical failure point. So the usual solution is a relatively large capacity, slow-revving engine.

One potential upcoming game-changer is emissions : the old-style IC engines are typically run lean of peak (LOP), which is a great way to produce NOx.
If GA emissions start to be regulated, a lot of current IC engines will be no longer viable.

[AW111]

Max_Torque said:

anonymous said:

[redacted]

Come on then, join in the fun! Take a stab at estimating the (bare) battery energy density required to make passenger aircraft viable. oh, and show your working / assumptions.... ;-)

Ok, would you accept 4 people + 50 kg luggage (say 500 kg including pilot), 150 kph cruise, and 2 hours endurance (plus 1/2 hr reserve)?

That's basically a short-range Cessna 172 equivalent, but you should get somewhat better Lift/Drag, due to both better airflow management possibly including a partially blown wing (Lift) and needing a lot less cooling (Drag).

wikipedia said:

The Cessna 172 Skyhawk is an American four-seat, single-engine, high wing, fixed-wing aircraft made by the Cessna Aircraft Company.[5] First flown in 1955,[5] more 172s have been built than any other aircraft.
...

Crew: one
Capacity: three passengers
Length: 27 ft 2 in (8.28 m)
Wingspan: 36 ft 1 in (11.00 m)
Height: 8 ft 11 in (2.72 m)
Wing area: 174 sq ft (16.2 m2)
Aspect ratio: 7.32
Airfoil: modified NACA 2412
Empty weight: 1,691 lb (767 kg)
Gross weight: 2,450 lb (1,111 kg)
Fuel capacity: 56 US gallons (212 litres)
Powerplant: 1 × Lycoming IO-360-L2A four cylinder, horizontally opposed aircraft engine, 160 hp (120 kW)

Cruise speed: 122 kn (140 mph; 226 km/h)
Stall speed: 47 kn (54 mph; 87 km/h) (power off, flaps down)
Never exceed speed: 163 kn (188 mph; 302 km/h) (IAS)
Range: 696 nmi (801 mi; 1,289 km) with 45 minute reserve, 55% power, at 12,000 ft
Service ceiling: 13,500 ft (4,100 m)
Rate of climb: 721 ft/min (3.66 m/s)
Wing loading: 14.1 lb/sq ft (68.6 kg/m2)

Edit : The previous version had 108 kW :

wikipedia said:

Crew: 1
Capacity: 3 passengers
Length: 24 ft 11 1⁄2 in (7.607 m)
Wingspan: 36 ft (11 m)
Height: 6 ft 7 in (2.01 m)
Wing area: 174 sq ft (16.2 m2)
Aspect ratio: 7.46:1
Airfoil: NACA 2412
Empty weight: 1,205 lb (547 kg)
Gross weight: 2,200 lb (998 kg)
Fuel capacity: 42 US gal (160 L; 35 imp gal)
Powerplant: 1 × Continental C145-2 air-cooled flat-six, 145 hp (108 kW)
Performance

Maximum speed: 140 mph (225 km/h; 122 kn)
Cruise speed: 120 mph (193 km/h; 104 kn)
Stall speed: 52 mph (84 km/h; 45 kn)
Endurance: over 4.5 hours
Service ceiling: 15,500 ft (4,700 m)
Rate of climb: 690 ft/min (3.5 m/s)

I've spent all week helping shift a business from the factory we've occupied for over 25 years, so I'll let someone else do the math - I'm knackered.

Edited by AW111 on Thursday 10th January 09:33

[IforB]

AW111 said:

I've spent all week helping shift a business from the factory we've occupied for over 25 years, so I'll let someone else do the math - I'm knackered.

Edited by AW111 on Thursday 10th January 09:33

172s can be fitted with all sorts of different power plants and therefore power outputs, from the O-300 with 140hp up to the Hawk XP version with the IO-360 giving 195hp.

GA aircraft though need to be thought of not in terms of their maximum fuel capacity and range, but in terms of their range at a useful load. Most things like a 172 are very limited once you actually put passengers on board and so you have to reduce your maximum fuel available drastically if you stick 4 adults on board for example.
If you use sensible margins, then you will find your useful endurance comes down to around 2-2 1/2 hrs. Not exactly a lot and definitely within the realms of what is being expected of this very first electric aircraft. An aircraft that also has significantly more performance as well.

This is where an electric GA aircraft would be a massive jump forward and really would revolutionise GA flying. Ok a charged battery may weigh marginally more than a discharged one, but in comparison with a hundred litres of fuel? It's not even worth thinking about.

This is why I am finding this thread frustrating. There is a lot of discussion about airliners, which are utterly irrelevant to this project and electric flight right now.

This project has huge potential in a market not even being discussed.

[TheDrBrian]

AW111 said:

(Copied and expanded from the other thread)

I can't see electric long-haul transport in the foreseeable future : energy density being the critical problem.

However, there are enough short-haul and recreational uses to make electric flight commercially viable, and I expect to see more in the near future.
An electric 4-seater with 300 km range and a cruising speed of 200 kph would sell if priced right, and that's not a million miles from this RR project.



Can we just agree that electricity replacing hydrocarbons for long-haul flight is not feasible in the near future, and look at where electric power is possibly viable?

One reason GA (General Aviation) is a likely target is because they are still using 50's engine technology - eg magneto ignition and caburettor on an air-cooled flat six.

IMO this is largely due to :

A very risk-averse regulatory environment, particularly in the US, so getting new designs approved is complex, time-consuming, and expensive.

A very litigious US (the major GA market) where manufacturers can and have been sued for user error.

And the fact that these types of aircraft are propeller limited - to use a modern, high revving automotive style engine requires a reduction gearbox, which is (relatively) heavy, and another critical failure point. So the usual solution is a relatively large capacity, slow-revving engine.

One potential upcoming game-changer is emissions : the old-style IC engines are typically run lean of peak (LOP), which is a great way to produce NOx.
If GA emissions start to be regulated, a lot of current IC engines will be no longer viable.

here’s the advantage of optimising for one speed, your 1950’s tech is holding up well against super whiz bang modern stuff.
Don’t know how well a modern car engine would hold up to 70% minimum load for most of it’s life either.

[AW111]

TheDrBrian said:

here’s the advantage of optimising for one speed, your 1950’s tech is holding up well against super whiz bang modern stuff.
Don’t know how well a modern car engine would hold up to 70% minimum load for most of it’s life either.

Ask max_torque what sort of BSFC he could get from a "super whiz bang modern" engine with no noise or emissions constraints, running high-octane fuel.

[Krikkit]

IforB said:

This is where an electric GA aircraft would be a massive jump forward and really would revolutionise GA flying. Ok a charged battery may weigh marginally more than a discharged one, but in comparison with a hundred litres of fuel? It's not even worth thinking about.

This is why I am finding this thread frustrating. There is a lot of discussion about airliners, which are utterly irrelevant to this project and electric flight right now.

This project has huge potential in a market not even being discussed.

Absolutely agree with this - GA is where electrification will make a big difference imho. Particularly in terms of safety.

[zombeh]

Absolutely, if you can get to 500Wh/kg it'd be of general use to a significant number of people, at 1000 it'd be useful to almost everyone.

Even the most negative of people about it aren't expecting or requiring the performance and range we have now with petrol, just enough to get where we want to go. If you have to stop a couple of times on the way to recharge it that's not too bad as long as you can do it in the time it takes to drink a coffee.

[dvs_dave]

Mave said:

dvs_dave said:

This is a very good point that has been confusingly ignored so far. It needs further emphasis and exploration.

Only around 1/3 of the total energy contained in jet fuel actually makes it out as pure propulsion, the only thing you actually want. The propulsive efficiency of a jet engine system is nowhere near what an electric propulsion system could achieve. I’d imagine that an electric propulsion system could easily be getting on for a propulsive efficiency of around 80%. So that means approximately only 40% of the onboard energy storage is actually required to achieve the same result.

The propulsive efficiency of a jet engine system is nothing to do with the prime mover - it's to do with making thrust by moving air. A particular propellor system for example would have the same propulsive efficiency whether it was powered by a turbochaft, a piston engine, or a wankel.

Whatever you call it, doesn’t change my point. The proportion of available energy in jet fuel that goes toward actual propulsion is way less than it is with electrical propulsion systems. Most of it disappears into the atmosphere as heat.

Therefore an electric system requires way less total energy storage to achieve the same result as there is far less wastage. Pretty much the same with electric cars. You don’t actually need like for like energy density storage (although it would be nice!) for electrical propulsion systems over fossil fueled. Just 40% of the energy storage capacity will net you the same result.

[IforB]

TheDrBrian said:

here’s the advantage of optimising for one speed, your 1950’s tech is holding up well against super whiz bang modern stuff.
Don’t know how well a modern car engine would hold up to 70% minimum load for most of it’s life either.

Shonky old lumps like lycomings and Continentals found in much of the GA fleet are light years behind in numerous ways.

They are ruinously expensive, Drink expensive leaded fuel, are noisy, easily damaged and pour a lot of nasties out of the exhaust.

I can assure you that they aren't holding up well. They are archaic compared to modern engines.

[Talksteer]

Max_Torque said:

Talksteer said:

As to your point, you come at electric as essentially a worse jet fuel.

It isn't, it allows you to do things that you couldn't with gas turbines and reciprocating engines.

Most basic example is the multi-rotor drone (now produced in greater total numbers than all other flying vehicles in history combined) which has allowed aircraft to be produced at costs and capabilities utterly impossible with liquid fuelled engines.

A multi-rotor is optimised for lift, but it does not use a "fixed wing" to create that lift. As such it has a really pretty poor L/D (typically less than ~5). That's fine for hovering, and low speed maneuvering, but hopeless for getting across oceans. It's easy to see this, just cut power to your drone at max speed, and see how far it glides for. (i think "flies like a brick" is probably actually a better description ;-)

I'm afraid i also fail to see how being able to make lots of small plastic "hobby" drones has significant impact on the costs of a full scale, fully certified passenger aircraft. The fundamental enabler for small drones is actually the high bandwidth of the rotor speed (and hence lift) control. Unlike an ICE engine (or worse still a jet engine) an electric motor can have it's torque modulated thousands of times a second, which has allowed the development of ultra fast "assisted" stability and control architectures. It's also worth noting that batteries scale reasonably linearly, unlike liquid fuel energy stores, which scale as a result of their surface area to volume ratio (ie bigger = better)

You miss my point, my point was that electric propulsion allowed us to make quad copters feasible, you have an easily controllable flying platform for £100. That could not have been done with liquid fuelled engines. Electric can allow us to make other design feasible because a motor driven fan scales down much better than a gas turbine.

Electric propulsion allows us to 1: Use commodity items to get the price down by orders of magnitude and 2: Allows us to distribute propulsion all over the airframe, it allows us to used the propulsion as the control surfaces and this allows aerodynamic configurations that would not be possible with liquid fueled aircraft.

Max_Torque said:

Talksteer said:

The F35B's L/D ratio is around 1/3 of what is possible, so your battery is now 8 tonnes.

I'm not sure it's that bad. It's dfifficult to find a best case figure for a "clean" F35B, but it looks to be around 14 to 15 at worst. 3 times that would be and L/D of 45, or about the same as a small, un-powered glider. I'm going to suggest that with current tech, that is far from possible.

The L/D of an aircraft changes as it goes faster, go supersonic and drops considerably. A modern fighter jet is basically designed to fly at around Mach 0.9 with occasional dashes at supersonic speed. At supersonic speeds its L/D is more like 4-5, this why they have afterburners and most struggle to reach Mach 2 clean (ask an actual fighter point what's the fastest they have ever been, most have got nowhere near their aircraft max speed), the supercruising fighters generally get only around Mach 1.2-1.5. Compare to Concord which went straight through Mach 2 with a much lower thrust to weight.

The reason for this is that we have three components of drag at supersonic speed, induced drag, skin friction and wave drag. A supersonic fighter has a few issues, firstly as a relatively small aircraft it has a relatively high ratio of surface area to volume and most importantly it has high wave drag. Ideally what you want is an immensely long thin and pointy aircraft with very gradual transitions between elements and in sectional area.

Concorde which was specifically design for high speed cruise has a supersonic lift to drag of around 7.5 it is very long and pointy, a fighter jet must have a wing optimised for turning (they are relatively short and wide for a supersonic aircraft), a raised cockpit, engine located in the main body fed by lossy inlets which protrude from the main body imposing abrupt changes in cross section. The F35 also has to hide weapons bays and a lift fan, the nose can't be as pointed as one would like as you have to fit a radar in it.

Concorde was somewhat compromised by 1960 aerodynamics and also manufacturing simplifications meaning it has a fuselage of the same cross section all the way along. Incremental improvements will get you to around L/D of 8-12 with Concord like proportions.

If you want to get to L/D 15 or so a very pointy (80 degree sweep) flying wing will get you to that level, but you need to do something clever to land your aircraft because your stall speed will be many hundred of miles per hour. The most fun one I have seen is to land it sideways as from that angle you now have very short aircraft with a very long wing!

The champion of supersonic L/D is the Pfenninger SST "extreme arrow" design which is a very thin strut braced wing which is highly swept, basically if you took only the first 3m of the leading edge of a Concord wing, the inner half is braced by a strut which runs to a drag reducing body on the mid span. Friction drag on the wing is reduced by sucking the boundary layer in. This design has a supersonic L/D of ~20, propulsion integration would have been a pain with turbines less so with distributed propulsors.

I don't know what the effect of laminar flow control on the extreme flying wing would be or how well the extreme arrow would do without it. Minor benefit of these very high L/D supersonic configurations is that they have inherently low sonic boom noises.

There is a legitimate question of why such designs have been lying around for 30 years, think the answer is that most technology is incremental and SST's got stuck at Concorde.

When Elon Musk is talking about his electric supersonic VTOL jet I think he is planning to use something along these lines. He also mentions flying at much higher altitudes which has a slight L/D advantage, it certainly allows you to achieve a higher speed for a given configuration and L/D.

[Mave]

dvs_dave said:

Mave said:

dvs_dave said:

This is a very good point that has been confusingly ignored so far. It needs further emphasis and exploration.

Only around 1/3 of the total energy contained in jet fuel actually makes it out as pure propulsion, the only thing you actually want. The propulsive efficiency of a jet engine system is nowhere near what an electric propulsion system could achieve. I’d imagine that an electric propulsion system could easily be getting on for a propulsive efficiency of around 80%. So that means approximately only 40% of the onboard energy storage is actually required to achieve the same result.

The propulsive efficiency of a jet engine system is nothing to do with the prime mover - it's to do with making thrust by moving air. A particular propellor system for example would have the same propulsive efficiency whether it was powered by a turbochaft, a piston engine, or a wankel.

Whatever you call it, doesn’t change my point. The proportion of available energy in jet fuel that goes toward actual propulsion is way less than it is with electrical propulsion systems. Most of it disappears into the atmosphere as heat.

Therefore an electric system requires way less total energy storage to achieve the same result as there is far less wastage. Pretty much the same with electric cars. You don’t actually need like for like energy density storage (although it would be nice!) for electrical propulsion systems over fossil fueled. Just 40% of the energy storage capacity will net you the same result.

But that 1/3 you've quoted for a jet engine is the combination of cycle efficiency (how efficiently you make high energy air) and propulsive efficiency (how efficiently you use that high energy air to make thrust). You can't compare it directly with an electrical system which only generates mechanical horsepower ready to turn a propellor or fan, and then ignore the propulsive efficiency term which accounts for the kinetic energy that the fan throws away. The energy that a jet engine throws away as heat is broadly similar to the amount it throws away as kinetic energy.

Edited by Mave on Thursday 10th January 19:43

[anonymous-user]

Mave said:

dvs_dave said:

Mave said:

dvs_dave said:

This is a very good point that has been confusingly ignored so far. It needs further emphasis and exploration.

Only around 1/3 of the total energy contained in jet fuel actually makes it out as pure propulsion, the only thing you actually want. The propulsive efficiency of a jet engine system is nowhere near what an electric propulsion system could achieve. I’d imagine that an electric propulsion system could easily be getting on for a propulsive efficiency of around 80%. So that means approximately only 40% of the onboard energy storage is actually required to achieve the same result.

The propulsive efficiency of a jet engine system is nothing to do with the prime mover - it's to do with making thrust by moving air. A particular propellor system for example would have the same propulsive efficiency whether it was powered by a turbochaft, a piston engine, or a wankel.

Whatever you call it, doesn’t change my point. The proportion of available energy in jet fuel that goes toward actual propulsion is way less than it is with electrical propulsion systems. Most of it disappears into the atmosphere as heat.

Therefore an electric system requires way less total energy storage to achieve the same result as there is far less wastage. Pretty much the same with electric cars. You don’t actually need like for like energy density storage (although it would be nice!) for electrical propulsion systems over fossil fueled. Just 40% of the energy storage capacity will net you the same result.

But that 1/3 you've quoted for a jet engine is the combination of cycle efficiency (how efficiently you make high energy air) and propulsive efficiency (how efficiently you use that high energy air to make thrust). You can't compare it directly with an electrical system which only generates mechanical horsepower ready to turn a propellor or fan, and then ignore the propulsive efficiency term which accounts for the kinetic energy that the fan throws away. The energy that a jet engine throws away as heat is broadly similar to the amount it throws away as kinetic energy.

Edited by Mave on Thursday 10th January 19:43

It's also worth noting that jet engines actually have a reasonably decent (~45% overall efficiency (total work out/ fuel energy in) because the "waste" heat does add to it's thrust, and hence useful work! With say a car engine, the useful work is only taken as mechanical energy from the crankshaft, all the heat that goes out the exhaust and into the cooling system is simply dumped overboard, with no net work being done on moving the car by that heat. But because a jet engine accelerates air to make thrust, the heat of the exhaust DOES add to the net useful work!

An electric to mechanical power transfer system (battery, inverter, motor) is typically around 85% efficient when all said and done at high to medium loads (which is what an aircraft will operate at most of the time) and a high efficiency propeller is also around 85% efficient at best, so overall efficiency is 72%. Sure that's better that say 45% but not by nearly enough to makeup for the startling lack of energy density in current batteries.



Roughly speaking:

Best "near future" batteries (ie best in say the next 3 years) at 500 W.h/kg vs 12,000 W.h/kg of kerosene = 24 times less energy dense.


Available energy consumption reductions in near future passenger airliner (let say targetted to be in-service in 2025 to 2030)

L/D improvements: 2 x lower drag (smaller engines, & "lifting body" fuselage)
Slower cruise speed design point: 1.5 x less drag
Propulsive efficiency: 2 x more efficient (electric systems + ducted fans)


Total consumption reduction: 6 times lower


So, the resulting range for the same overall airframe mass (assuming landing at MTOW isn't an issue) = 24/6 = 4 times less.

[dvs_dave]

Ok, so using those ^^^^ present day efficiencies (the best of a mature technology vs an emerging technology), the power density of a battery needs to be around 60% that of kerosene to net the same results, all else being equal. So just over 7,000 Wh/kg.

A modern airliner has a L/D of around 20, and I heard someone mention previously that future electric propulsion aircraft would likely have an L/D of 30. So 50% better. Not sure how that relates exactly to energy consumption, but assuming a ball park linear relationship, it’ll require 66% of the energy to perform the same task.

So 66% of 7,000 Wh/kg gives around 4,500 Wh/kg as the magic energy density number required. Or 8-10 times what the best of present tech can do. It’s a big difference for sure, but over the next 20-30 years I don’t think it at all inconceivable that it gets bridged.

[ukaskew]

Just sticking my head out of lurker mode to wish the OP luck with this project and hope that they are able and willing to supply updates.

I fully appreciate and respect other experts involvement in this thread, and even if intentions are good it's pretty clear reading it from scratch that the thread has been overpowered somewhat (even if on-topic).

[anonymous-user]

ukaskew said:

Just sticking my head out of lurker mode to wish the OP luck with this project and hope that they are able and willing to supply updates.

I fully appreciate and respect other experts involvement in this thread, and even if intentions are good it's pretty clear reading it from scratch that the thread has been overpowered somewhat (even if on-topic).

I suspect the OP is not really at the same liberty they were when working on the LSR project to release any actual detail. This is after all a commercial project by RR, and the findings, experience and techniques used are therefore their proprietary info!

[JuniorD]

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