mass yield and minimo consumption

[Fulvio Romano]

perhaps there is a misunderstanding in the terms used
I have understood "work" as what I need to go from to b and should be independent from the fate that is done at a speed or another. I mean by work the energy spent to move the body between two points having different potential.

certainly there is a misunderstanding only on terms. However, you talk about "work" like energy spent against a potential field, such as gravitational one. if the points are at the same height, the work is null.

I say instead that the work, which is a force for a shift (see discharging with pierarg) is greater if the force is greater. and since the increase in friction, the force also increases (otherwise the car does not go to the desired speed) , the work will also be greater.

What is the difference between work and mechanical energy? I would say that's the same thing, but if someone explains me, I'm ready to deny this statement, to say that I never wrote it or believed it, and that these words are actually written by an alien who took possession of my account.

"the thermodynamic god is always worth, everywhere and anyway! also in a pisci@t@ in the middle of the desert losses are proportional to the square of speeds!" [cit.]

ehm... mi iuterest?

se le losses are proportional to the square of speeds, the power power spending must be proportional to the cube.... Am I wrong?? ?

Why? if the losses are x, and then the energy will be x, the power will be x/t.

In fact the spark is in the words of the president. above a certain speed actually (and I had not thought about it) aerodynamic resistance begins to prevail. Let's not talk about viscous friction, let's talk about vortices behind the car that pulls it back. that these go with the cube of speed... I do acknowledge faith, I am very ignorant in aerodynamics. . .

 

[MBT]

ehm... mi iuterest?

You can't know. . .
He's an educator.
Maybe you know him. I have heard that he now cooperates with you.

on the rest... I have to think about it calmly and this is not the right time...:redface:

 

[Antosacca]

as is known the ra is due only to the shape of the vehicle (transverse section and length).
the ra grows exponentially, see diagram and growing consumption.
then the answer to the question:

x is greater or less than y?

dipende da ra (cx)

 

[mir]

Okay, guys, the hippo is the friction.

- work force x shift is the same for both shifts
- the point of performance (we only talk about the thermal one to simplify) maximum is only one for the motor

mentioned above only if I make the path to maximum efficiency consumption as little as possible.

If I now consider air resistance then I could consume less slowly!

probably the aerodynamic performance falls much to the growth of speed and this explains why the consumption is much higher in the face of a better thermal/mechanical performance.

Are we all in agreement?

 

[Er Presidente]

Okay, guys, the hippo is the friction.

- work force x shift is the same for both shifts
- the point of performance (we only talk about the thermal one to simplify) maximum is only one for the motor

mentioned above only if I make the path to maximum efficiency consumption as little as possible.

If I now consider air resistance then I could consume less slowly!

probably the aerodynamic performance falls much to the growth of speed and this explains why the consumption is much higher in the face of a better thermal/mechanical performance.

Are we all in agreement?

The performance of the entire vehicle, of which the engine is only one of the components.
when you know the speed (or speeds, it could be more than one) of maximum performance, that will be the speed in which you will have the least consumption for the route (economic cruise speed). any other speed, higher or lower will lead to greater energy consumption.

 

[Er Presidente]

as is known the ra is due only to the shape of the vehicle (transverse section and length).
the ra grows exponentially, see diagram and growing consumption.
then the answer to the question:


depends on ra (cx)

quoto, aerodynamic resistance is the most important one over a speed of about 100 km/h (where you see the "knee" in your post).

 

[athlon]

In fact, a machine that moves slowly is nothing but a way to heat the air and the tires, the slower you go, the less energy you turn into heat, in my opinion (and in my experience) the faster you go, the less you consume, a car with the second ungrateful and the engine at the least (no accelerator) is the more efficient way to move, obviously it takes a lot of time.


I made a journey to dakar with an electric car from self-built me and at 45km/h I had about 200km of autonomy, 50 about 140 and 55 less than 100, the energy contained in the batteries is always the same (19 kwh) , changes only how much I throw away in heat

 

[rawdraw]

I made a journey to dakar with an electric car from self-built me and at 45km/h I had about 200km of autonomy, 50 about 140 and 55 less than 100, the energy contained in the batteries is always the same (19 kwh) , changes only how much I throw away in heat

I am illiterate on electric traction vehicles (not that on others I know long), but always that the variation of speed of the vehicle is given by a variation of angular speed of the motor, and not by a variable transmission ratio, perhaps it also enters into play a different turn of performance of this engine than an endothermic. Speed differences from 45 to 55 are low, as well as speeds in itself, and generally with endothermic engines should not have these variations of consumption. In this specific case I think that they do not depend mainly on the increase of air resistance.

 

[Er Presidente]

the electric motor (depending on the types) has a substantially constant performance in wide rotation regimes, the performance of the vehicle is more influenced by the rolling friction of the tires and aerodynamics than other, which increase with the increase of the speed.
an endothermic engine (the entire power transmission chain) has a more complex performance curve and, therefore, the behaviour of the entire vehicle is not so linear.

 

[athlon]

In my case the big variations are due to a very bad cx, very bad, practically horrible given by an old r4 without roof, with the open windows, a solar megapannellone of almost 2 meters x 4 meters and all the rest instead optimized, rubbers inflated to 5 atmospheres, oil change new and slightly more liquid than normal.

speeds are low because the engine of the machine is a rated 4kw induction powered at 72v dc (50v on the three-phase) so more so it can't go.
http://www.ecowiki.it/r4-elettrica-e-fotovoltaica-da-milano-a-dakar.html


.

 

[Antosacca]

I made a journey to dakar with an electric car from self-built me and at 45km/h I had about 200km of autonomy, 50 about 140 and 55 less than 100, the energy contained in the batteries is always the same (19 kwh) , changes only how much I throw away in heat

wonderful adventure.