Red Bull RB8 Renault

[Adrian Newby]

I'll have to remember to tell the stressers that next time they go to calculate the loads on wing spars.

You do that. And they will laugh at you.

Wing spars do not have a support at each end.

Go draw yourself out a little shear force diagram of the estimated load across the wishbone.

Then draw out a bending moment diagram.

Then, draw out a point load on the wishbone which represents all the aerodynamic loading through a single point - the centre of pressure.

See the distance from the centre of pressure to either end - those are the effective lever arms that will tell you what proportion of load will be sent to the car's springs and what proportion will go directly to the upright.



Your desperately trying to trip me up to hit back for your mis-speak earlier (I don't really know why, is your ego that delicate?). But to be honest your failing miserably.

I'm not desperately doing anything, I did not mis-speak, and you should quit while you are behind.

Put a board across two saw horses. Pull down on the board anywhere between the two saw horses. There is no lever.

[avatar]

I had a think through this when I read it - as the chassis is suspended from the wheels, I think any df from the arm can be considered unsprung can't it?

Nah, some of it will go directly to the upright and from there into the wheel.

Some of it will go back into the car through the inner wishbone mounting point. From there, it'll load the spring and will push the chassis into the track. That proportion will of course come back through the pull-rod to the wheel, but not before it has affected the car's springs - which would be the definition of sprung/unsprung.

Ah, so the energy from the df portion you're talking about goes into suspension squat, so is behaving like regular sprung df.

[i70q7m7ghw]

How in depth would you like to go?

In-depth enough so it is not completely 100% incorrect!

It was a simplified explanation for someone who seemed not to have been exposed to it before.

Diesel has been here since 2006 - he got a fair idea what is happening.

In answer to the original point, I believe the wishbones have a maximum allowable angle of slant (5 deg IIRC) from the chordline to ground plane. So they can generate some downforce; but due to the small surface area, very limited cambering and very limited AoA, it will be negligible in the grand scheme of things.

That was NOT an incorrect explanation of Bernoulli's principle, which was what I was trying to explain, in a simple fashion. If you want to go into further detail, then have at it. I think it is beyond the scope of this thread, and the point I was trying to make.

The upper wishbone does not need AoA to generate downforce if it has that much more flow, and higher-energy flow at that. The small surface area would be the largest limitation, but even at that it will have a more substantial effect than you suggest due to the fact that half of the downforce generated will go directly into the wheel/tire/contact patch.

Steady on now guys, I actually wasn't looking at the suspension arm next to the exhaust point, I was looking at the one further downstream. Blowing the underneath of the upper wishbone makes sense, I just completely missed the fact they were doing it on the front half of the wishbone

[kilcoo316]

Ah, so the energy from the df portion you're talking about goes into suspension squat, so is behaving like regular sprung df.

Uh, kinda.

All of the downforce generated will act through the wheel eventually, just some of it acts through the car's springs first.

Its all usable downforce though. Both sprung and unsprung downforce.

[kilcoo316]

Put a board across to saw horses. Pull down on the board anywhere between the two saw horses. There is no lever.

Ach, I can't be arsed anymore.


Go study the principle of virtual work and get back to me... in fact, its not even that complex... go study static structural mechanics and get back to me.

[Adrian Newby]

Put a board across to saw horses. Pull down on the board anywhere between the two saw horses. There is no lever.

Ach, I can't be arsed anymore.

Go study the principle of virtual work and get back to me... in fact, its not even that complex... go study static structural mechanics and get back to me.

You are flat wrong, and you are making this harder than it really is. Man up, correct your mistake, and move on.

[shelly]

That was NOT an incorrect explanation of Bernoulli's principle, which was what I was trying to explain, in a simple fashion. If you want to go into further detail, then have at it. I think it is beyond the scope of this thread, and the point I was trying to make.

It was completely incorrect - and it barely even addressed Bernoulli's law.

"Bernoulli's principle can be used to calculate the lift force on an airfoil if the behaviour of the fluid flow in the vicinity of the foil is known. For example, if the air flowing past the top surface of an aircraft wing is moving faster than the air flowing past the bottom surface, then Bernoulli's principle implies that the pressure on the surfaces of the wing will be lower above than below. This pressure difference results in an upwards lift force."

I suggest reading the famous " Stop abusing Bernoulli" book

[Adrian Newby]

"Bernoulli's principle can be used to calculate the lift force on an airfoil if the behaviour of the fluid flow in the vicinity of the foil is known. For example, if the air flowing past the top surface of an aircraft wing is moving faster than the air flowing past the bottom surface, then Bernoulli's principle implies that the pressure on the surfaces of the wing will be lower above than below. This pressure difference results in an upwards lift force."

I suggest reading the famous " Stop abusing Bernoulli" book

That was a quote from Wikipedia. I made it clear that I was explaining Bernoulli's principle, which is exactly what I did. Lengthy discussions into more depth and detail and alternate explanations/theories can be had elsewhere if anyone is interested. I am not Bernoulli. I did not invent his principle.

Ironic that I didn't go into more detail about the principles of lift because I was afraid it would take us off-topic!

[kilcoo316]

You are flat wrong, and you are making this harder than it really is. Man up, correct your mistake, and move on.

I am really, really not.

Go get yourself a copy of Bruhn - even it has a whole rake of stuff on easy things like this. It'll do you a world of favours. I've even opened up my copy to get you a page to go to, A2.7 and example problem 8 - nice and simple for you to follow.


Anyhoo - this is my last post on it. If you want to continue to be blissfully ignorant, so be it, not my problem.

[Adrian Newby]

You are flat wrong, and you are making this harder than it really is. Man up, correct your mistake, and move on.

I am really, really not.

Go get yourself a copy of Bruhn - even it has a whole rake of stuff on easy things like this. It'll do you a world of favours. I've even opened up my copy to get you a page to go to, A2.7 and example problem 8 - nice and simple for you to follow.


Anyhoo - this is my last post on it. If you want to continue to be blissfully ignorant, so be it, not my problem.

Yes, you really, really are. I'm not trying to be harsh, but this is as simple as physics gets. Sorry.

[shelly]

wikipedia is not very accurate on this subject then.
"Air travelling faster that has to rejoin at the trailing edge etc.etc" is not correct.
The book is good, only difficut to find. There are different opinios about it also, on amazon.com

Did not want to sound harsh, but this type of discussion on this forum often lack good base grasp of the basics.
Agree with you that you do not want air dams on the nose; I personally think that the famous hole is a boundary leayer ingester.

[Adrian Newby]

wikipedia is not very accurate on this subject then.
"Air travelling faster that has to rejoin at the trailing edge etc.etc" is not correct.
The book is good, only difficut to find. There are different opinios about it also, on amazon.com

Did not want to sound harsh, but this type of discussion on this forum often lack good base grasp of the basics.
Agree with you that you do not want air dams on the nose; I personally think that the famous hole is a boundary leayer ingester.

Wikipedia is correct that that is bernoulli's principle. You can find information about other lift theories on Wikipedia, and much more thorough information on Bernoulli's principle as well. My objective was a quick summary of Bernoulli for someone I did not think was acquainted with any theory of lift at all, so I could make a simple point. I had no idea it would open this can of worms for people who wanted to discuss lift theory in more detail. My contention is that they should do that on another thread.

[JB2011]

RB8 exhaust in action

This seems to be a significant distance further back than McLaren's exhaust exit. Why wouldn't McLaren also mount them this far rearward and then add on their extra bit of bodywork?

[Adrian Newby]

For the air dam theory, the fences would be what stops the air also pushing outwards....

If they're just using the slot to bleed off air pressure at the hump, hen it would be simpler to splurge it off to the sides...

You don't want air splurging off the sides.[\b] And if the air dam didn't extend forward of the ramp area then what's the point of it?

I believe Adrian Newey is attempting to have the exact the opposite effect of an air dam. [ b]He is trying to get rid of any build up of air caused by this newly necessary hump in the nose[\b] by routing air through the bulkhead, past the driver, and out the cockpit opening.

As I said if they're (note they not he) primarily trying to reduce pressure, would it not be simpler to get rid of the pressure to the sides?

The effect of the drag on the top of the nose is minimal.

If so, why work so hard to remove the air pressure. If it's ducted somewhere, IMHO the exit is where it will be paying it's way.

You're right, that we all want to see this year's bulkhead - I should have know that photo of last year's was too good to be true!

The main objective for the area in between the front tires is to keep from impeding the flow to the front of the undertray. Primarily, that means keeping the underside clean, and without impediment. Secondarily, keeping the sides clean and without impediment. New rules have made the designers lower the nose, but to keep the underside clean the designers have kept the chassis as high as the rules allow. That has created a hump on the top of the nose. This hump forces the oncoming air to go up and over it, but also around it. This air impedes the flow on the sides by making a narrower gap between it and the front tires. Newey's solution, in my opinion, is to let that air go through the hump, and exit through the cockpit opening.

[Adrian Newby]

RB8 exhaust in action

This seems to be a significant distance further back than McLaren's exhaust exit. Why wouldn't McLaren also mount them this far rearward and then add on their extra bit of bodywork?

It will be interesting to see who got their exhaust right coming out of the gate. If one is a clear winner, it should be easy enough for the other teams to copy the placement of the exhaust, but maybe not so much the parts it might be aimed at (such as the suspension members).