F1technical.net

stevesingo wrote:

bergie88 wrote:[quote="Facts Only"

Fuel flow limit doesnt increase above 10,500rpm (I believe)

Exactly, this is defined in the rules by a formula which increases with rpm till 10.500rpm, after which it is limited to a certain value. This is also shown by the calculation of stevesingo. For this reason the ICE is designed to reach its peak efficiency around 10.500 rpm, because the most fuel per cycle times maximum efficiency results in the highest peak power.

10500rpm is the point of highest flow, but not the point of highest fuel per cycle. The way the formula works (I don't know why the FiA did this) means the lower the rpm the higher the fuel flow per cycle at a rate of about 1% increase per 1000rpm below 10500rpm.[/quote]

FIA rules state that you cannot use 100kg/hr fuel flow at an rpm less than 10500

peak flow per cycle will be at point of highest torque which would be around 120000 rpm

stevesingo wrote:

bergie88 wrote:

Facts Only wrote:
Fuel flow limit doesnt increase above 10,500rpm (I believe)

Exactly, this is defined in the rules by a formula which increases with rpm till 10.500rpm, after which it is limited to a certain value. This is also shown by the calculation of stevesingo. For this reason the ICE is designed to reach its peak efficiency around 10.500 rpm, because the most fuel per cycle times maximum efficiency results in the highest peak power.

10500rpm is the point of highest flow, but not the point of highest fuel per cycle. The way the formula works (I don't know why the FiA did this) means the lower the rpm the higher the fuel flow per cycle at a rate of about 1% increase per 1000rpm below 10500rpm.

FIA rules state that you cannot use 100kg/hr fuel flow at an rpm less than 10500

peak flow per cycle will be at point of highest torque which would be around 120000 rpm

WilliamsF1 wrote: .....FIA rules state that you cannot use 100kg/hr fuel flow at an rpm less than 10500
.....peak flow per cycle will be at point of highest torque which would be around 120000 rpm
http://i.imgur.com/pMHl9vv.jpg

@ WilliamsF1
presumably you meant 12000 rpm not 120000 rpm
peak fuel flow permitted per cycle is highest below 10500 rpm

the plots show peak power around 12000 rpm or less
they don't show torque - is there a torque plot somewhere within the source material ?
from the power shown at 10500 rpm relative to that shown at 12000 rpm , it seems to me that peak torque is not at 12000
it's at maybe 10500 in self-sustaining mode
and more like 9500 with battery useage

WilliamsF1 wrote: FIA rules state that you cannot use 100kg/hr fuel flow at an rpm less than 10500

peak flow per cycle will be at point of highest torque which would be around 120000 rpm

http://i.imgur.com/pMHl9vv.jpg

Above 10500rpm the fuel per cycle reduces significantly as the rpm and therefore cycles per min is increasing, but the fuel flow is not. I posted the fuel mass available per cycle (with workings out) a few posts back.

RE the graph:

I see the following (approx) in self sustain mode;

8000rpm -470bhp
9000rpm -530bhp
10000rpm-590bhp
11000rpm-600bhp
12000rpm-600bhp

tq(lb/ft)=bhp/rpm*5252

8000rpm -309 lbft
9000rpm -309 lbft
10000rpm- 309 lbft
11000rpm-286 lbft
12000rpm-262 lbft

Edited to use ICE only data.

WilliamsF1 wrote: peak flow per cycle will be at point of highest torque which would be around 120000 rpm

This doesn't make any logical sense because the fuel flow limit is constant from 10500-15000, so obviously beyond 10500 rpm less fuel can be burned per cycle.

With regard to fuel you should be comparing to the ICE only line. i.e. without the mgu-k input as that just complicates the picture and is unrelated to available fuel.

mrluke wrote:With regard to fuel you should be comparing to the ICE only line. i.e. without the mgu-k input as that just complicates the picture and is unrelated to available fuel.

Quite right.

Post edited and we now have a flat torque curve from 8-10k rpm.

stevesingo wrote:

bergie88 wrote:10500rpm is the point of highest flow, but not the point of highest fuel per cycle. The way the formula works (I don't know why the FiA did this) means the lower the rpm the higher the fuel flow per cycle at a rate of about 1% increase per 1000rpm below 10500rpm.

The rule was implemented to force the engines to use more rpm. Originally it was to be a flat 100kg/h fuel flow rate, but that led to fears of low-revving engines.

Quick question that's been bugging me for a while now. Just wondering if anyone knows the reasoning behind the 200nm torque limit on the mgu-k, given there is also the 120kw power limit?

it's a necessary practical limit on generation via KE recovery ie in the braking zone
as DF falls away at slow speeds reduced adhesion won't allow more than 200 Nm (crankshaft-referred) MGU-K generation torque
even with rear friction brake torque (reducing via 'brake-by wire' software action as speed reduces) approaching zero
loading the generator to more than 200 Nm would tend to lock or under-rotate the rear wheels and generate little

it's also a limit on generation outside the braking zone
ie limiting the scope for the burning of fuel to make electricity for storage
(this would improve ICE efficiency when little power is required at the wheels)
preventing any apparently freakish ways of operating the PU

it's a practical limit in the interest of all designers peace of mind and ....
more torque means more current, bigger and/or less efficient power electronics ie more heat
more battery waste heat and a bigger or less efficient, shorter life battery

power = voltage x current
voltage is proportional to rpm
but torque is proportional to current, and power loss from resistance (ie heat) proportional to current squared

so, limit the torque and keep the rpm up
motoring or generating

The name of the game in this formula is energy recovery and deployment.

I think Ferrari and Mercedes are employing hot blowing in the corners and braking zones to increase the MGUH energy transfer to the battery to store the energy for use later down the straight. To limit excess power and wheels spin in the corners, the engine may be mapped to retard ignition to similar levels in the Blown diffuser days, only such that the excess energy is used for charging the battery. It is not the most efficient use of fuel but it it will definitely add significantly to energy sent to the ERS.

I agree - in fact if you weren't doing that then you'd have to ask why, wouldn't you?

Nobody is using the full 100 kg.

One downside is carrying extra fuel mass which you convert into stored electrical energy at low efficiency but I bet it pays back.

http://www.somersf1.co.uk/2015/11/power ... right.html

Axel Plasse - Renault - 2005:

“On average, every percent of power you gain is worth 0.12 seconds (per lap). You can also have in mind that 10 hp is a bit more than 0.12 sec. or 1 hp is a little more than 1/100 of a second.”

http://speedtalk.com/forum/viewtopic.php?f=1&t=2343

Juzh wrote:http://www.somersf1.co.uk/2015/11/power ... right.html

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For today’s Formula 1 cars adding 1% more power (let’s call this 8 horsepower) the car will go about 0.14 seconds faster (varies track to track and with ambient conditions).  - See more at: http://www.somersf1.co.uk/2015/11/power-more-is-always-better-right.html#sthash.Js8EQcjL.dpuf

I saw this article on Joe Sawards' blog. WIlliam Toett is the author I believe. He normally writes for James Allen. I am not sure if that is Somer's original content. Might be Saward's...