whats wrong with the renault engines?

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R_Redding
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Re: whats wrong with the renault engines?

Post by R_Redding » Sat Mar 08, 2014 3:30 pm

Tommy Cookers wrote: Whittle complained about all the 'wonder' piston engines whose optimistic projections undermined the position of his work
OT...sorry.
One aspect of the RR Crecy not normally noted was the noise levels it produced.
Anecdotally... when they ran the engine in Derby ...it could be heard in Nottigham 15Miles away...often triggering their anti aircraft defences. Any pilots would have been deafened by it,very much worse than the Sabre pilots were.

I hate the usual Whitworth "everbody in the Ministry Hates him and held him back" story that is usually pedalled by the TV Media.
The real argument between Whitworth and the Ministry (by that I mean A.A. Griffith) was the fact that Griffith saw the future as axial flow and Whitworth was using developing a radial.
A.A. Griffith went on to work for Metropolitan Vickers to develop the axial engine...which even in the war years was well ahead of Whitworths...and Griffiths axial engine has a lineage all the way to the Olympus engines used in Concorde.
Whitworths radial engine was obsolete and history by 1955 when the Nene was cancelled.
The real A.A. Griffith Vs Whitworth story is fascinating when you delve into it.

Rob

Pup
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Re: whats wrong with the renault engines?

Post by Pup » Sat Mar 08, 2014 5:18 pm

munudeges wrote:What a driver feels and the effect on the car itself is not in any way down to torque at all.

Power = Torque x RPM. That's the be all and end all.

What the driver feels as 'torque' is low end power, or power in the lower RPM band.
You can't reduce the equation to torque and then claim that torque is meaningless. You can't even include torque in the equation and then claim that it's meaningless.

bhall
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Re: whats wrong with the renault engines?

Post by bhall » Sat Mar 08, 2014 6:05 pm

I think his claim is that torque is only effective when combined with speed, at which point you're talking about power.

Per
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Location: Delft, the Netherlands

Re: whats wrong with the renault engines?

Post by Per » Sat Mar 08, 2014 6:09 pm

Yes. If you want a lot of torque, drive in first gear. I wonder why no-one thought of that before. :P

bhall
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Re: whats wrong with the renault engines?

Post by bhall » Sat Mar 08, 2014 6:54 pm

Well, I can make more "torque" with a decent pipe wrench and my bare hands than any racing engine, but what good would it do me without speed?

(That's for you, X.)

I haven't yet figured out how to power my laptop with torque, though. Still working on that one...

tathan
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Re: whats wrong with the renault engines?

Post by tathan » Sat Mar 08, 2014 7:58 pm

Yes, if only there were a way of applying a torque to a shaft that generated electricity :D

autogyro
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Re: whats wrong with the renault engines?

Post by autogyro » Sun Mar 09, 2014 1:42 am

tathan wrote:Yes, if only there were a way of applying a torque to a shaft that generated electricity :D
There is a way the result is piezoelectricity.
It is very useful for sensors that measure torque.

Pup
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Re: whats wrong with the renault engines?

Post by Pup » Sun Mar 09, 2014 2:12 am

bhallg2k wrote:I think his claim is that torque is only effective when combined with speed, at which point you're talking about power.
The point though is that if you're going to talk about power at a specific RPM, the only variable is torque.

bhall
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Re: whats wrong with the renault engines?

Post by bhall » Sun Mar 09, 2014 4:03 am

I'm not exactly sure how this one got started here, but just to put a period on my involvement...

What a driver feels in the seat of his/her pants when driving is not the result of an engine's torque output, but of its power output, because the driver feels the level of acceleration permitted by the engine's peak power, and that's generally created at a higher RPM than is the case for peak torque. When a driver talks about "low-end torque" or a "torquey engine," they're actually referring to an engine with a wide power band.

When the goal is speed, any speed whatsoever, power is everything.

Put ridiculously: manufacture an ultra-super-mega-lightweight car from pure unobtainium, complete with an engine that creates a mammoth 1,000,000 lb-ft of torque, yet somehow only manages 1 hp in the process, and I'll beat it in a race with a kitten trained on the spot to ride a tiny bicycle.

(Great. Now I want to actually see that.)

Tommy Cookers
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Re: whats wrong with the renault engines?

Post by Tommy Cookers » Sun Mar 09, 2014 9:50 am

autogyro wrote:
tathan wrote:Yes, if only there were a way of applying a torque to a shaft that generated electricity :D
There is a way the result is piezoelectricity.
It is very useful for sensors that measure torque.
generating electricity is intended to mean a continuous transfer of energy ie something useful ?
our generators do this by having a continuous motion through an electromagnetic field

the piezoelectric effect is an electric field phenomenon
at a steady torque there is no energy transfer ie no 'generation'
going to that steady torque from zero has produced an internal ('charge') energy, allowing eg a voltage proportionate to torque
so we can use this as a torque sensor
but eg to attempt to do some work that charge must be exported, thereafter nothing further can happen
unless/until eg the torque is removed and then reapplied
this process can be useful as a switching signal to control energy drain eg from a continuous electromagnetic source
..... ie we can have a piezoelectric trigger based ignition system
but the source of the spark energy is not piezoelectricity, but some external electromagnetic system

torque is analogous to voltage
these both are a reference to some internal system state, not an expression of energy transfer from that system

WillerZ
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Re: whats wrong with the renault engines?

Post by WillerZ » Sun Mar 09, 2014 2:21 pm

bhallg2k wrote:Put ridiculously: manufacture an ultra-super-mega-lightweight car from pure unobtainium, complete with an engine that creates a mammoth 1,000,000 lb-ft of torque, yet somehow only manages 1 hp in the process, and I'll beat it in a race with a kitten trained on the spot to ride a tiny bicycle.
No you won't: the kitten wouldn't get off the start line. 1HP is a lot.

Cat cycling performance hasn't been studied, but: 2.3W/kg (sustained) is good specific power output for an untrained human male cyclist. Felines are morphologically unsuited to cycling and intractable to training so their output is likely to be lower. At 6 months old (the oldest you could still think a cat was a kitten) a heavy cat weighs 3kg and could therefore produce at most 7W.

The rolling resistance of bicycle tyres has been extensively tested by (among others) Germany's Tour magazine, who report that you need around 30W to make a bike with the best available tyres (Continental GP 4000S) move at all. So your kitten is going nowhere.

1HP is 745W (give or take). I don't know so much about the tyres you might be able to fit to your imaginary car, but you could always use 4 of the same bicycle tyres for a total RR of 60W, leaving 685W from the engine to overcome aerodynamic drag and so forth; certainly enough to outpace a stationary kitten.

The_Mauler
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Re: whats wrong with the renault engines?

Post by The_Mauler » Sun Mar 09, 2014 2:36 pm

WillerZ wrote:
bhallg2k wrote:Put ridiculously: manufacture an ultra-super-mega-lightweight car from pure unobtainium, complete with an engine that creates a mammoth 1,000,000 lb-ft of torque, yet somehow only manages 1 hp in the process, and I'll beat it in a race with a kitten trained on the spot to ride a tiny bicycle.
No you won't: the kitten wouldn't get off the start line. 1HP is a lot.

Cat cycling performance hasn't been studied, but: 2.3W/kg (sustained) is good specific power output for an untrained human male cyclist. Felines are morphologically unsuited to cycling and intractable to training so their output is likely to be lower. At 6 months old (the oldest you could still think a cat was a kitten) a heavy cat weighs 3kg and could therefore produce at most 7W.

The rolling resistance of bicycle tyres has been extensively tested by (among others) Germany's Tour magazine, who report that you need around 30W to make a bike with the best available tyres (Continental GP 4000S) move at all. So your kitten is going nowhere.

1HP is 745W (give or take). I don't know so much about the tyres you might be able to fit to your imaginary car, but you could always use 4 of the same bicycle tyres for a total RR of 60W, leaving 685W from the engine to overcome aerodynamic drag and so forth; certainly enough to outpace a stationary kitten.
I´m sorry but, whats wrong with the renault engines?

FoxHound
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Re: whats wrong with the renault engines?

Post by FoxHound » Sun Mar 09, 2014 2:44 pm

@WillerZ

Magnificent! Thoroughly enjoyed reading that....I'm perplexed as to how you know this however.
JET set

bhall
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Re: whats wrong with the renault engines?

Post by bhall » Sun Mar 09, 2014 5:07 pm

WillerZ wrote:No you won't: the kitten wouldn't get off the start line. 1HP is a lot.

Cat cycling performance hasn't been studied, but: 2.3W/kg (sustained) is good specific power output for an untrained human male cyclist. Felines are morphologically unsuited to cycling and intractable to training so their output is likely to be lower. At 6 months old (the oldest you could still think a cat was a kitten) a heavy cat weighs 3kg and could therefore produce at most 7W.

The rolling resistance of bicycle tyres has been extensively tested by (among others) Germany's Tour magazine, who report that you need around 30W to make a bike with the best available tyres (Continental GP 4000S) move at all. So your kitten is going nowhere.

1HP is 745W (give or take). I don't know so much about the tyres you might be able to fit to your imaginary car, but you could always use 4 of the same bicycle tyres for a total RR of 60W, leaving 685W from the engine to overcome aerodynamic drag and so forth; certainly enough to outpace a stationary kitten.
This is great! I stand corrected.

PlatinumZealot
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Re: whats wrong with the renault engines?

Post by PlatinumZealot » Sun Mar 09, 2014 6:00 pm

Tommy Cookers wrote:the turbo lag without mgu-h motor action seems to be an order of magnitude worse than in turbo engines
this should be no surprise, the turbine is, depending on engine rpm, 2-4 times the size needed to drive the compressor
and it has a 120 kW machine hanging on to it via a clutch
the inertia must be about an order of magnitude greater than in a turbo engine
Not just this.. the MGU-H itslef is dead weight (or correctly, dead inertia) when it isn't powering the turbocharger. So yeah the turbo lag is increased even more by having an MGU-H just being there. Depending on the control method used, the generation or motorizing greatly depends a lot on the transient behaviour the turbocharger and the rotating mass of the MGU-H PLUS any magnetic field effects have to be as an input into the system. It is a very delicate balance: you either get huge boost spikes and hence wheel spin (as reported) or you get an endless loop of turbo lag if you didn't do your home work.
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