Ask The Apex

[Galahad]

With the long summer break underway and the fantastic influx of new members I thought I'd start a thread for those niggling questions that some of us have eating away at us from time to time, but which we might feel embarassed about asking. As far as I'm concerned there should be no limits here, doesn't have to be anything technical, or even F1-specific.

I would ask before we start that everyone who asks a question is given their due respect. Remember, none of us knew the answers to anything until someone told us. So let's share the wealth eh?

I'll kick off with two things that trouble me from time to time:

1) The turbo cars didn't have roll-hoop mounted airboxes, but the atmospheric cars (both before and after) did/do. What specifically was it about the turbo engines that explains this? So far as I know they need an air intake like any other engine. Some turbo cars had little chimney intakes on the sidepods, but not all, e.g. Benetton B186.

2) Before the start of the season the FIA crash-tests all the F1 teams' new monocoque chassis. I note that the HRT cars that turned up at Bahrain were numbered #01 and #02. So are those crash-tested tubs discarded following the tests, or can they be used again for racing (assuming they passed, obviously)?

Any answers or educated guesswork much appreciated. And if, like me, you have more questions than answers, feel free to bung them on here.

 

[Brogan]

I don't have any answers to those but I do have a question of my own which I have raised before on here.

Why, when road going sports cars have ultra low profile tyres, do F1 cars have very small wheels with very large profile tyres?
Doesn't that introduce problems with sidewall flex and cause problems with keeping the pressure and temperature constant, which is why they use nitrogen?

Is it because it provides a form of suspension or is there another more important reason?

 

[Muddytalker]

Good thread idea G

I checked our friend wikipedia for 1) "A turbocharger is a small radial fan pump driven by the energy of the exhaust gases of an engine. A turbocharger consists of a turbine and a compressor on a shared shaft. The turbine converts exhaust heat and pressure to rotational force, which is in turn used to drive the compressor. The compressor draws in ambient air and pumps it in to the intake manifold at increased pressure, resulting in a greater mass of air entering the cylinders on each intake stroke."

So I guess the intakes were sidepod mounted (or in the early Ferraris, and the mentioned Benetton B186 engine cover mounted) due to location of the turbo itself? Whilst searching, I saw that other teams like Brabham used NACA ducts

 

[FB]

A picture paints a thousand words - these are courtesy of the Renault F1 team from 1980 which (I hope) will explain how a turbo charged F1 car breathes.

 

[Galahad]

Fantastic stuff, thanks FB!

I had gone off on a tangent looking at cutaway diagrams actually. So my interpretation is that with twin intercoolers, one for each bank of cylinders it makes sense from a packaging and weight point of view to have side inlets and the whole shebang as low down as possible, rather than on top?

What about inline-4 turbos like the BMW? Did they have twin intercoolers like the V, or single?

 

[fat jez]

I've stickied this for now, so that new members should see it at the top of the page.

 

[FB]

The original Renault RE01 only had a single turbo charger feeding the vee but to get more power they moved to two. I think the original reason for only having a single turbo was balancing the two banks of pistons, once they worked out how to set the turbo chargers up properly they could use two.

The BMW 4 cylinder (I believe) only ever had a single turbo but the power was increased by having a bigger turbo - the larger the turbine the more air it moved into the engine. Attached is a scan from Alan Henry's F1 - The Turbo Era showing the installation of the BMW engine in the back of a Brabham. Not sure if it would have had twin intercoolers, the problem would be getting the air from the far side of the car to the turbocharger so I would assume one. If I can find a cut away of a Brabham I'll post it.

 

[Speshal]

Great topic.

2) Before the start of the season the FIA crash-tests all the F1 teams' new monocoque chassis. I note that the HRT cars that turned up at Bahrain were numbered #01 and #02. So are those crash-tested tubs discarded following the tests, or can they be used again for racing (assuming they passed, obviously)?

I'm a tad bored/ing - I've been looking thru the technical regs and I can't find anything stating what happens to the chassis/tub after the crash test, I'd assume that as they can fix them after a race incident (presuming it's not wrecked or changed*) they could fix them after a crash test.

The side impact test - is a mass of 780Kg hitting at 22.2Mph
The front imact test - " " " " " " " 33.3 mph

So doesn't sound like they will be too knackered to fix and run?

*Article 18.1.9 states that if you alter a part it must undergo the same tests, so they have to test all new nosecones I would assume?

 

[Brogan]

The side impact test - is a mass of 780Kg hitting at 22.2Mph
The front imact test - " " " " " " " 33.3 mph

Slightly off topic but I would have thought the impact tests would be far more testing than that!
22.2Mph and 33.3Mph equates to about 10m/s and 15m/s. Where did they pluck those figures from?

 

[Bullfrog]

Those speeds seem very low, I'd have expected them to be much faster.

*edit* Jinx!

 

[Galahad]

The original Renault RE01 only had a single turbo charger feeding the vee but to get more power they moved to two. I think the original reason for only having a single turbo was balancing the two banks of pistons, once they worked out how to set the turbo chargers up properly they could use two.

The BMW 4 cylinder (I believe) only ever had a single turbo but the power was increased by having a bigger turbo - the larger the turbine the more air it moved into the engine. Attached is a scan from Alan Henry's F1 - The Turbo Era showing the installation of the BMW engine in the back of a Brabham. Not sure if it would have had twin intercoolers, the problem would be getting the air from the far side of the car to the turbocharger so I would assume one. If I can find a cut away of a Brabham I'll post it.

Thanks FB, that makes sense. I found this terrific link about the BMW engine: http://www.gurneyflap.com/bmwturbof1engine.html but frankly my untrained eye has difficulty in untangling exactly what is what and where.

 

[FB]

Don't know much on the specifics of crash tests but here are a couple of videos of a nose cone and rear impact protection being destroyed.

 

[Speshal]

The side impact test - is a mass of 780Kg hitting at 22.2Mph
The front imact test - " " " " " " " 33.3 mph

Slightly off topic but I would have thought the impact tests would be far more testing than that!
22.2Mph and 33.3Mph equates to about 10m/s and 15m/s. Where did they pluck those figures from?

I refer m'learned friend to article 16.2 that states must be "no less than 10 m/s" - I never said that was the maximum

*Edit ^ the 2nd video above is at 15 M/s

 

[FB]

Brogan asked:

Why, when road going sports cars have ultra low profile tyres, do F1 cars have very small wheels with very large profile tyres?

One reason for F1 using 13" wheels is because the rim is heavier than rubber so a smaller wheel makes lighter wheel/tyre combo. This would help the designers with their weight distribution and, I would presume, allow them to make the suspension units lighter as they have to support less weight. A heavier wheel/tyre would also increase the stress on the drive shafts & gear box. I found a thread which estimated the increase in weight of going to 18" rims as being as much as 33KG - about 5% of the weight of an F1 car.

 

[Brogan]

Stupid question time...

If the cars have a minimum weight of 620kg, if the wheels were heavier (due to e.g. 18" rims) then doesn't that mean that the body of the car can weigh less?
Which means the suspension is supporting less weight?

 

[FB]

The body of the car would be lighter but the weight being supported at the end of the suspension would be greater and the wheels would be more difficult to turn as they're heavier. Larger diameter wheels/tyres have less rolling resistance though, hence why a racing bike has such large wheels.

 

[FB]

Here's one maybe some of you computer boffs can help me with. I understand basically how CFD and wind tunnels work but does anyone understand how these models can be adapted to the driver simulators? For example at the British GP Mclaren tested the EBD and the standard diffuser on the simulator and came to the conclusion that the standard was better. The programming involved in this must be immense.

 

[Brogan]

The body of the car would be lighter but the weight being supported at the end of the suspension would be greater

Nope, I still don't get it.

The wheels are resting on the ground so the suspension only supports the weight of the car, not the wheels.

 

[siffert_fan]

The suspension pieces would have to be stronger because stiffer sidewalls=more deflection=greater force. Additional compliance would also have to be designed in, as the sidewalls of the current tyres flex enough to act as a form of suspension themselves. Also, engineers being engineers, larger wheels would undoubtedly lead to larger brakes to fill the available space.

The use of ("dry") nitrogen in tyres is primarily to eliminate the presence of water vapor in the inflation medium. Water expands phenomenally when it turns to steam (that's how steam locomotives work) and modern race tyres work at such high temperatures that that expansion can change the pressures dramatically.

 

[F1Yorkshire]

Here's one maybe some of you computer boffs can help me with. I understand basically how CFD and wind tunnels work but does anyone understand how these models can be adapted to the driver simulators? For example at the British GP Mclaren tested the EBD and the standard diffuser on the simulator and came to the conclusion that the standard was better. The programming involved in this must be immense.

I can't answer the whole question but it CFD is able to compute airflow and downforce but there's probably nothing in the program that allowed for the extra heating of parts due to the exhaust gases. This is why the actual car on track ended up performing differently to how they predicted. Once McLaren had run the EBD a few times they were able to put the information into the simulator to get a more accurate feel to the car.

There's a link that explains a little about Ferrari's 200 tonne simulator. Yes I did say 200 tonnes, which is about the same weight as Flavio's lunchbox.

http://www.gizmag.com/ferraris-f1-simulator/13666/