Renault R31

[ringo]

The front exhuasts were in fact a good concept. It's not that it didn't work or that it failed.
Its achilles heel is the fact that it depends too much on the air speed to work like it is intended to.
Which is really saying that the effect only worked under limited circumstances around the track.

And another point of view is that the system was ahead of its time. It is beyond our limitations, technologically, to properly tune the exhuast system to work with maximum effect under all wind speeds. The engineers simply could not develope the exhaust shape to manipulate such an uncontrolable and speed sensitive flow.

The dependcy on air spreed presented a dilemma. How do you get the exhuast which is at 90 degrees at zero windspeed, and angles at increasing air speeds, to be at the optimal angle all the time?
The added dependency on air speed has greatly restricted the systems functionality.

A rear blown diffuser doesn't give a rat's navel about wind speed as it's slapped on right over the diffuser. Being in only one position the optimal one, it's only dependency is engine speed, and it will create downforce according to engine speed only.

When the rear blown car is in a slow turn, it's blowing at full tilt, in the intended place as soon as the driver steps on full throttle. Instant downforce.

When the front exhuast car is in a slow turn and the driver steps on it, the engine will rev and the exhuat will blow fully. The catch is the direction it is blowing. It is not blowing in the intended place.
At slow speeds the thing is blowing near to 80 degrees!
So the exhuast speed energy is almost useless at that angle, as it blows into thin air.

While the rear blown car is creating downforce on the rear axle and is pulling out of the turns will surplus grip. The front blown car is huffing and puffing, but has to wait for the car to speed up before the exhaust flow bendw in toward the car. By then the car is already out of turn fully.
The FEE is almost like a big turbo that has to spool up. Only that it's not the driver's foot that determines it. It's the air speed!!

This is the whole failure in the R31. The car is as good an any car once the blown floors are removed. I dare say the car is top 3 all blowing being ignored.

It only has that one critical unforeseen issue.

[BreezyRacer]

For all this talk about a failed design, let's not forget the early season competitiveness of the car. In the end it couldn't match the Newey design blown diffuser which was pretty easy for other teams to copy, though not get full benefit from it.

In any case, Renault's efforts should be hailed in the engineering community. They stepped out and took that chance rather be a copy team.

There ought to be points or an award given for aero and mechanical innovations without regards to wins .. maybe even excluding race winning cars. There isn't enough risk taking in F1 these days IMO, and maybe an award like that would serve to remind people of these innovations. Now that I think about it, I think F1Tech ought to have an award like that. Readers could vote on it or it could be determined by the mods on F1Tech. I would trust the mods more than the members myself. I'm going to propose that in a new thread.

[scarbs]

Renault have a unique Inerter concept on the car, using fluid (mercury) rather than a spinning mass. Full analysis on my blog.... http://scarbsf1.wordpress.com/2011/11/2 ... d-inerter/

[hardingfv32]

Scarbs

You state that: "but (the design is) restricted from copying by other teams". Is this correct? I was under the impression you can copy and use any patent item, but can not sell such copies.

Brian

[scarbs]

I could be wrong, I'm no patent expert.

[ringo]

What makes it different than a typical shock absorber?

My reading of the article is saying to me we have a shock with mercury instead of oil.

I have an interpretation of what the diagram is saying, but i want your feedback first. As i have not read the patent.

There is something i was going to point out in regards to vibration absorption. But i don't want to jump into that if it's a false alarm.

[thisisatest]

typical dampers force oil through small orifices, dampers are force sensitive. springs are position, or displacement, sensitive.
inerters are acceleration sensitive.
this one has a passage from one end of a through-shaft damper to the other, with a long, coiled tube between them. it's filled with heavy mercury. any damper movement forces the piston to push mercury to high speeds (it's a relatively small diameter tube) and it takes a while for all that mass to accelerate.
it's the same as adding a cinder block to the upright, unsprung-mass-wise, but without the actual weight penalty. it's a benefit because with such high spring rates, the suspensions basically have a high natural frequency, and so do undamped tall tires. inerters lower the natural frequency of the suspension, and the tire bouncing around interacts with the suspension less.
that's my understanding of it, at least.

[thisisatest]

Scarbs

You state that: "but (the design is) restricted from copying by other teams". Is this correct? I was under the impression you can copy and use any patent item, but can not sell such copies.

Brian

this is a gray area as i understand it.
what definitely cant happen, though, is a damper company cannot develop this design and sell it to their partner f1 team. so the fluid inerter would have to be done completely in-house (if at all-gray area)

[The FOZ]

The front exhuasts were in fact a good concept. It's not that it didn't work or that it failed.
Its achilles heel is the fact that it depends too much on the air speed to work like it is intended to.
Which is really saying that the effect only worked under limited circumstances around the track.

And another point of view is that the system was ahead of its time. It is beyond our limitations, technologically, to properly tune the exhuast system to work with maximum effect under all wind speeds. The engineers simply could not develope the exhaust shape to manipulate such an uncontrolable and speed sensitive flow.

Oh Ringo...you and your bendy logic.

1. Value as a concept is irrelevant in exercises of practicality. Something that works only some of the time is by it's very nature unbalancing, as it produces more varied situations for the driver to anticipate and adapt to. There's a reason off-throttle blowing is so popular...it produces consistent effect! The team that figures out how to smooth out KERS harvesting to not mess with brake balance is going to have an advantage, too!

2. Ahead of it's time, inadequacy of LRGP engineers, say what you want...front and side exit exhausts didn't perform, and there was a simpler solution out there that worked globally. The proof of the pudding is in the eating...just for some reason LRGP stuck with it while MGP stopped flogging a dead horse and shortly thereafter magically started flogging LRGP. More proof? How many teams were running successful EBD setups by seasons' end?

3. Your talk about direction relative to the car's direction is sensible...but coming to the conclusion that it's a shortcoming of engineering that they can't manipulate exhaust flow direction through a fixed aperture of fixed dimension in fixed position while airflow around it changes...is bunk. This is fundamental fluid behavior, I don't think that can be changed.

[The FOZ]

Scarbs

You state that: "but (the design is) restricted from copying by other teams". Is this correct? I was under the impression you can copy and use any patent item, but can not sell such copies.

Brian

Sorry to stick my oar in...depending on the jurisdiction, and the patent type, patents can apply to production, usage, sale, or marketing of an invention.

This may be an interesting strategy designed to keep other teams from gaining this technology, through the use of patent court proceedings rather than the usual "get it banned" approach teams may otherwise take.

I think the trouble looks very similar to a damper, and burden of legal proof would be on LRGP to prove another team is running it...but how do you do that without spying? Further, it would be tough to haul a team in front of a court on infringement because those teams would argue protection of trade secrets to avoid disclosure of information to support infringement claims.

Unless LRGP simply see more value in this invention through licensing or selling of the patent, which would adequately explain this course of action.

[ringo]

Oh Ringo...you and your bendy logic.

1. Value as a concept is irrelevant in exercises of practicality. Something that works only some of the time is by it's very nature unbalancing, as it produces more varied situations for the driver to anticipate and adapt to. There's a reason off-throttle blowing is so popular...it produces consistent effect! The team that figures out how to smooth out KERS harvesting to not mess with brake balance is going to have an advantage, too!

You are talking philosophy here. I am talking science. It's not about driver adaptation at all. The thing simply doesn't work as low speeds.

2. Ahead of it's time, inadequacy of LRGP engineers, say what you want...front and side exit exhausts didn't perform, and there was a simpler solution out there that worked globally.

Yes there were limitations on the design. It's like a helicopter, while the rear blown diffuser is a baloon. 2 different concpets, one more complicated, but they were intended to do the same thing. Which one is harder to manipulate, a balloon or helicopter?

3. Your talk about direction relative to the car's direction is sensible...but coming to the conclusion that it's a shortcoming of engineering that they can't manipulate exhaust flow direction through a fixed aperture of fixed dimension in fixed position while airflow around it changes...is bunk. This is fundamental fluid behavior, I don't think that can be changed.

What do you mean by bunk?
You don't think it can, but you don't know. I am sure i mentioned technological limitation. It can't be done now, but you can't rule it out.
It's a simple fact that the system has a shortcoming. It was an oversight, regardless of the effort the engineers put in.

[ringo]

typical dampers force oil through small orifices, dampers are force sensitive. springs are position, or displacement, sensitive.
inerters are acceleration sensitive.

An inerter is a vibration damper. A damper is a damper. Springs are neither here nor there for the discusion.

Damper is not force sensitive by definition. It is speed sensitive.

My question is why is this damper functionally unlike other typical oil filled or gas filled dampers.

I have an answer to that question, but i want to hear what this thing is doing differently first.

inerters lower the natural frequency of the suspension, and the tire bouncing around interacts with the suspension less.
that's my understanding of it, at least.

Is that so?

Anyway let me point out something that was probably overlooked, a preamble to the answer:

[thisisatest]

my apologies:
spring=position sensitive
damper=speed sensitive
inerter=acceleration sensitive

it is different from a shock absorber in that it doesnt absorb shock. actually, it works against absorbing shock, as you effectively have a lot more unsprung weight.

[hardingfv32]

Scarbs clearly describes what the inerter is about.

http://www.montefiore.ulg.ac.be/doc/smith09.pdf

This article gives a black and white engineering explanation. What else is required? You understand the article or not?

Brian

[PhillipM]

Something that was overlooked? That's just the bump stop, it's a nice place to package it.

Anyway, although an inerter like this will have some inherent damping effect, it's primary purpose is to store bursts of energy from the suspension and release it when that energy input reduces, if you tune it right you can not only improve the body control, you can also control the oscillations from the tyre sidewalls.