Efficiency​ in Power Unit in F1

Following the post Engine Management in F1 and Mercedes new about achieve more 50% efficiency  in F1 engine, I want show my opinion about this milestone.

In this post I suppose that we know how works the ICE (Internal Combustión Engine) with its four times

ICE otto cycle 

In a ICE with turbo compressor, the compressor increase the pressure into the combustión chamber in inlet time.

Turbo compressor layout

The turbo is designing to increase the ICE power, but in the case in F1 this is linked to  MGU-H, and this is a electric engine, one point to remenber into de turbo is that rpm is "proportional" to inlet pressure.

In several webs show the MGU-H like one system to mitigate turbo compressor behaviour that it is knew like Lag turbo.

One summary about lag turbo is, when engine works low load, the rpm in turbo and compressor is low because dont need more pressure to provide power.

But when we need power, engine pressure is low and we need increase this pressure with increase rpm in compressor, and this lag is the time that turbo exchange exhaust pressure in rpm. This rpm depend to pressure in exhaust gases, and when we have low pressure inlet ICE, we have  low pressure in exhaust (less air to burn less exhaust gases). Therefore we need to reach the rpm to increase the pressure in the compressor and this increases pressure in the exhaust, and this effect have a feedback, but this feedback have a lag time that it is measure in seconds (depend of the turbocompressor size).

Therefore in the F1, the MGU-H increases turbo compressor rpm with electric engine, and it doesn't have lag time.

Another effect that it is not explaining,it is works like electric generator too, if you keep turbo compressor rpm, although exhaust gases pressure try to increase this rpm, meanwhile extract electric energy.

Turbo shaft engine

Turbo shaft engine is one engine that use the same principle that ICE with turbo compressor, but the the power is not in the crankshaft, the power is transmitted to turboshaft (turbo compressor shaft)

This engines is used in airplanes and helicopters because the ratio weight/power is very low, and they are small.

TPE331

For example the TPE331, is a small engine, like motorbike engine, and reach between 700 and 1000 HP, like a F1 Power Unit, and normally turboshaft have more efficiency that ICE.

This version is more complicate and provide 1600HP with less maintenance

In this video we can see the size of TPE331

Turbo shaft in Formula 1

We can see the big reduction gearbox in turboshaft engine due to the rpm in shaft is very high, but in the MGU-H don't need the gearbox because we could design the electric generator to work at those rpm.

With the same principle, we could use the turbo compressor into the engine, an then like I exposed in the Engine Management in F1 , this power could be send to batteries or MGU-K.

The relationship between MGU-H and MGU-K is the  same behaviour tan gearbox in the turboshaft,but electrical relationship, therefore we could a mix engine Turbo compressor ICE and Turboshaft engine, and this relation doesn't be limited by energy regulation in Formula 1 (4MJ per lap).

How history we could to see the Chrysler Turbine have a car with Turboshaft like engine, and the problema was:

• Maintenance, this engine works to high rpm and increase material wear, (remember this design in 1960 and they didnt have to current materials and the quality manufacture that we have today)
• Consumption, this engine dont have Start-Stop and to máximum power have a great efficiency, in idle or mid load the consumption is high if we compare with ICE engines.
• Overheat, extract the heat is one problem in this engines, now we have studies with the simulations, and could be resolve this problem with low speed air to cool if we compare against airplane or helicopter.
• Rpm range to use the engine with best behaviour is  smaller than a ICE.
• Noise, all people that live near of airport could be explain this inconvenence.

MotoGP aerodynamics

In the last test IRTA in Sepang, Yamaha showed the next step in MotoGP aerodynamics.

Fairing with ducted vanes

Technical regulation is forbidden aerodynamic appendices, therefore if you want to work with aerodynamic, only you have shape and ducts in the fairings.

Fairings are reason for aerodynamic existence, and the first goal is to down Cx in the motorbike.

Low Cx is less aerodynamic drag, and more top speed with same power, but this is dead end way when the top speed is all.

We take Honda RC213V values,

• width = 0.645m
• height = 1.110m
• Area = 0.562 m2 (Elipse área wuth height and width)
• Cx = unknow

However we have hayabusa Cx = 0.561, and could be estimate that the MotoGP more and less 0.5 and 0.6

	Cx	200 km/h	300 km/h	355 km/h
Hayabusa	0,561	45 HP	152 HP	252 HP
MotoGP	0,5	40 HP	136 HP	225 HP
	0,6	48 HP	163 HP	270 HP

We could see that the top speed is reachable by motoGP is the same that, but big part of circuit the power is superior than you need, the famous wheelie is this fact, engine to provide more power that bike could take to increase the speed.

Conclusion, top speed is only one point in track and more than 90% in the track, engine provides more power than motorbike can manage it.

Therefore, 90% in the track, we can power waste.

How? One way is aerodynamics effects, in the 2016 season we saw wings in all motorbikes, but in 2017 is forbidden wings, but wings are not all aerodynamics. we could explore two ways,

1. Slots and coanda effects
2. Lifting body

Yamaha show the first field, with ducted vanes to provide Coanda effect. is for air viscosity create boundary layer and air follow this profile meanwhile dont broke it, (stall effect).

Coanda effect follow the profile

But the coanda effect has other behaviour, and this could see in the Hunting H126 and it jet flaps.

jet stream drag the surrounding air in the same direction

Jet stream, deflect the air ans create lift

You could work with this effect, and create air paths in the surface, like diverterless, this effect could see in the F35 Lightning II engine intake.

This is DSI shape and it has other advantages in supersonic speeds

Lifting body create lift forces without wings, due to the body is a wing

With this effect and "dowforce" body, and ducted jet stream we could create down force, like the old wings.

Drag creates for in air intake is converted in downforce. Purple lines is air flow.

One point where could be create this effect is in the nose fairing

The nose is a big surface where Coanda effect works, and it begins the rest aerodynamic behaviour.

Sepang test,  M1 show this ducted

Yamaha M1 ducted vanes

If the make the first calculates with the effective vanes, and only the effect the flow deflection and Cx=1 (all air into the ducted is deflected).

• Intake width = 0.1m
• Intake height = 0.3m
• Intake area = 0.03 m2 

YZF-M1

200 km/h

300 km/h

350 km/h

2 Ducted vanes

11,6 kg

26,1 kg

36,5 kg

MotoGP wings analysis

Then of MotoGP season 2016 where the all motorbikes y all categories was mount wings.

Today is banned, but I'd like on resume of simple analysis of effects and how it works. 

I am sure  that in the future the aerodynamics into motorbike have more weight in the design, the aerodynamics is not high relevant value, but in one world, where each tenth could be mark win or lose one race, aerodynamics can provide this tenth.

Aerodynamics basic concepts

Angle of Attack

The main effect is the angle between air and profile depend lifts generate, until one point where profile lost lift and only provide more drag, (stall angle)

Angle of Attack

Lift and Drag Equations

D is the drag force, which is by definition the force component in the direction of the flow velocity

L is the lift force, which is by definition the force component in the perpendicular of the flow velocity

  is the air mass density  1.205kg/m3.

v is the flow velocity (motorbike speed).

A is the reference area, (wings surface).

Cd is the drag coefficient provide for NACA profile data. 

Cl  is the drag coefficient provide for NACA profile data.

For calcule I used information with NACA profiles (this information is public in NASA webs)

Aerodynamic analysis 

Wing analysis

Ducati GP16 courtesy from Ducati

I estimate several measures

• Wheelbase 1400mm
• Rear SAG with pilot 30mm
• Fork travel 110mm
• Pitch full brake (fork fully compressed, rear wheel without load, rearshock extended) 5.7º
• Wing area 250mm x 100mm

Ducati GP13 braking

In the front part I used a thin profile NACA 65-206. This enter in stall quickly and provide low lift (Cl < 1) (down force) and low drag, this wing was used for Yamaha YZF-M1

• Straight mode with motorbike with full gas we put the Angle of attack (AoA) 6º
• In full brake the motorbike pitch 5.7º, therefore the AoA is 11.7º

NACA 65-206 charts

With 11.7º, this profile is in stall, this point is in brake, therefore Drag increase and provide a braking extra. The table provide the several data (10 N ~ 1 kg ~ 2.3 lb)

NACA 65-206	6,0º					11,7º
	100 km/h	200 km/h	300 km/h	350 km/h		100 km/h	200 km/h	300 km/h	350 km/h
L	8,14 N	32,54 N	73,22 N	99,66 N		2,32 N	9,30 N	20,92 N	28,47 N
D	0,46 N	1,86 N	4,18 N	5,69 N		1,39 N	5,58 N	12,55 N	17,08 N

In the side part I used a thin profile NACA 6412. This provide high lift (Cl > 1) (down force) and high drag, this wing was used for Ducati GP16

• Straight mode with motorbike with full gas we put the Angle of attack (AoA) 7.5º
• In full brake the motorbike pitch 5.7º, therefore the AoA is 13.2º

NACA 6412 charts

With 13.2º, this profile provide more lift, this point is in brake, therefore provide more force to tyres (like a weight) and provide a braking extra. The table provide the several data (10 N ~ 1 kg ~ 2.3 lb)

NACA 6412	7,5º					13,2º
	100 km/h	200 km/h	300 km/h	350 km/h		100 km/h	200 km/h	300 km/h	350 km/h
L	17,43 N	69,73 N	156,89 N	213,55 N		5,81 N	23,24 N	52,30 N	71,18 N
D	0,23 N	0,93 N	2,09 N	2,85 N		1,39 N	5,58 N	12,55 N	17,08 N

However, these profiles try to create less drag possible, therefore  if you have enough power to waste in drag, you could be increase the Lift forces. 

For example we can increase AoA without stall and increse Lift with slots in the profile 

In the F1, the top in racing aerodynamics Cl is over 3

Source Racecar Engineering

If we calculate with Cl 3 

Ranurados	Cl 3
	100 km/h	200 km/h	300 km/h	350 km/h
L	34,87 N	139,46 N	313,79 N	427,10 N

Each wing, generate 43kg with 350km/h, with 4 wings (one front one lateral, in each side) reach  174kg , this is the same weight of one MotoGP without rider

Behavior effects 

Another effect is the rider change his position in the bike, this create changes in aerodynamics

Motorbike Magazine courtesy

In corner when the rider try to leave the bike vertical and launch his weight to turn side, it create a wall where stop the airstream, and the lateral wing lost efficiency, and the other side create a roll effect like the rider put weight in the opposite side, this effect aid to take the turn.

Other effects in in the brake the pitch increase the Drag and Lift, and this provide more capacity to brake.

The antiwheelie effect, but normally, the speed in the exit is less and this effect is not the more important, beacuse, the wheelie is stronger in short gear, and this translate to low speeds

General drag, the vortex could be create two effects

1º Low the general drag like a golf ball, locate vortex provide less general drag

Locate vortex decrease the general drag 

NASA studies

2º Create a concentre vortex behind the bike, where concentrate turbulence and the motorbike behind shake by this turbulende. The air intake to engine could be affected for this tubulence. In 2016 season  riders complained for this effect. 

Security

The problem is if wing hit a rider in one accident or overtake. We could see that Force that must withstand so that it does not brake the fairing, therefore it must and hard part and could be injure to riders. Cruchtlow  warn this effect, and he has reason.

This is the first reason to ban the wings, other reason is cost increase due to aerodynamics studies.

In the future I will develop other post with how develop aerodynamics forces in the motorbike without wings.

Why the car electro is farthest from what it seems?

Independently of engine technologies, substitute engine must provide the same service that actual engines. The electric engine could be reach the power of ICE (internal Combustion Engine).

We take like base a VW Polo 1.2

• Fuel consumption (town) 5.8 L/100km  
• Fuel consumption (highway) 4.1 L/100km  
• Average fuel consumption 4.7 L/100km 
• Engine Power kW 81 kW
• Average trip with full tank 1125 km (703 miles)
• Weight 1163 kg

We need to compare with fossils fuels, mainly isoctane (petrol) that have 11,778 Wh/kg; 42.4 MJ/kg. but in this case we set efficiency around 30%.

Internal Combustion Engine
Pretol	Energy	42.4 MJ/kg
	Density	0.748kg/L
	η	30.00%
Consumption each 100 kms		4.10 L	100 kms
		3.06 kg
Energy Consumption 100 kms (EPetrol)		129.9 MJ
Energy used in 100 kms (EPetrol x η)		39.0 MJ

If we suppose 1,125 kms with constant speed without energy recovery possibility, we need (39MJ/100kms x 11.25kms) 438.56 MJ to move the car this distance and we could use this value like standard.

Batteries technologies 

BATTERIES
TECHNOLOGIES	MIN		MAX
Lead	30 Wh/kg	108 kJ/kg	40 Wh/kg	144 kJ/kg
Ni-Fe	30 Wh/kg	108 kJ/kg	55 Wh/kg	198 kJ/kg
Ni-Cd	48 Wh/kg	173 kJ/kg	80 Wh/kg	288 kJ/kg
Ni-Mh	60 Wh/kg	216 kJ/kg	120 Wh/kg	432 kJ/kg
Li-ion	110 Wh/kg	396 kJ/kg	160 Wh/kg	576 kJ/kg
Li-Po	100 Wh/kg	360 kJ/kg	130 Wh/kg	468 kJ/kg
Ultra Capacitor	7 Wh/kg	27 kJ/kg	7 Wh/kg	27 kJ/kg
Fuel Cell	14,400 Wh/kg	51,840 kJ/kg	33,333 Wh/kg	120,000 kJ/kg

If we take the best current batteries technology, it is the Li ion and  for use the 438.56 MJ we need 761.4 kg. This is the weight of current Polo.

Second problem is the mean life of batteries the batteries life is around 200 cycles of 2.5 years, (guarantee power > 90%). Several test show that the life is 8 years, and one packet batteries is $8,000-$12,000.

The other problem is the  manipulation conditions, the voltages maximum should not exceed 50-60V. Several regulations and mechanics without experience with high voltage electrical systems, we should think in secure manipulation for this workers.

Making numbers

Our model of Engine Power is 81 kW with 50-60V we need 1,620-1,350 A and the maximum power.

In the 1,125kms, if we suppose the constant speed 100km/h is 11.25h or 675 min or 40500 s, therefore if we use 438.56 MJ, the engine should provide 10.8 kW meanwhile we keep constant speed. 10.8 kW with 50-60V we need 217-180 A.

The losses in electric system mainly is heat losses to internal resistance:

The internal resistance of one cell is near of 0.03 ohms.

Range	1125 kms
	438,6 MJ
Average Speed	100,0 km/h
Time	40500 s
Power for 100 km/h	10,8 kW
Voltage	50,0 V	60,0 V
Current	217 A	180 A
Internal resistance	0,03 Ω
Internal losses	1,41 kW	0,98 kW
	12,99%	9,02%

The internal losses is a problem near of 10% of losses therefore, the efficiency is now  90%, but it is following 3 times more efficiency than ICE.

Everybody have contact with this fact, for example when we charge or use laptops, tablet, mobiles or smartphones... any PED (Portable Electronic Device) with batteries, we feel how it is heated, hence we can think, that cell packs need refrigeration systems in the electric cars, due to size.

Lattice Energy LLC slide

But we calculate with maximum power, the losses are increased exponentially.

Max power	81,0 kW
Voltage	50,0 V	60,0 V
Current	1620 A	1350 A
Internal resistance	0,03 Ω
Internal losses	78,7 kW	54,6 kW
	97,20%	67,50%

However batteries, is a cell packs and depend how we make the packet


Each pack is compound by several cells

Cell element	3,7 V	12,00 Ah
	0,25 kg	30,00 mΩ

 Cells is connected in serial and parallel circuit, and we can calculate more aproximation to real datas.

Cell pack	Series cells	14 S	17 S
	Parallel cells	135 P	113 P
	Num cells	1890 Cells	1921 Cells
	Weight pack	480,38 kg	488,25 kg
	Voltaje pack	51,8 V	62,9 V
	Capacity pack	1620 Ah	1356 Ah
	Ampere pak	1620 A	1356 A
	Energy pack	302,10 MJ	307,05 MJ
	Max Range pack	775 kms	788 kms
	Power 1hour	83,92 kWh	85,29 kWh
	Internal R Pack	3,11 mΩ	4,51 mΩ
	Internal loses Max range	136 W	134 W
		1,26%	1,24%
	Internal loses Max power	8.165 W	8.299 W
		9,73%	9,73%

We can see that the datas improve respect de last calculus, and efficiency is near 10%

Infrastructures problems

The other problems is civil installations, the electrical instalations for private use (homes).

The regulations expose mandatory near of 10kW instalations but the electrical services is not sizing for this power in all house. The Electrical Companies apply a simultaneity factors where, all consumers don't use together the max power. (this factor is important due to efficiency, if don't use near 100% of capacity, the efficiency is less)

Normally this simultaneity factor is near to 50%, and the service for electrical installations is for 5kW per house. Therefore the time to recharge is increased.

Recharge time	9kW	9h 19,4min	9h 28,6min
	5kW	16h 37,3min	17h 54,2min

One solution for this problem is a Tesla Powerwall, for example where, it is charging all day and it provide the fast charge to car, when we need, like a power bank for a PED, or like a hidroelectrical dam. The problem is in each charge point need similar power that batteries car. Therefore the double batteries one in car and other in power bank (remember 760kg in lithium or 3 tonnes in lead-acid bateries).

World Lithium Reserve

This current estimate totals 28.4 billion kilograms Li, for one billion cars in the world, therefore is 28.4kg per each car, there fore this source (now mainly material for batteries), it dont have future.

Now is development other batteries technologies like Fuel cell, but now is expensive and need more development.

The future is electric car, however you dont await in next years. Maybe, the next decade.