Aero benefit of exposed beams

I question the aero benefits of exposed front beams.

When compared to a FV, the larger beam spacing of a FST might make create more drag from increased frontal area than the benefit from an improved Cd. if one was using a large single fairing.

So then let us look at each tube having its own fairing. I know what the English FV RCE article said, but under what circumstances do you think a round beam is going to be better than aero shaped beam? Doesn't an aero shaped tube always have flow better?

Brian

My TUNNEL VISION CFD version 6.6.6 tells me that an all enveloping nose, shock tower to shock tower, produces less drag than exposed tubes or individually streamlined tubes.

Such a nose also provides more foot room, and space for the ballast needed to obtain that "perfect" 50/50 weight distribution.

The next single best improvement regards less drag at the front end was to leave off the front brake hoses, followed by leaving off the tie rods.

My next effort will be to study replacing the shock actuator rod with a set of 3/32 wire push pull cables. If a suitable system of cable shock operation is not found, I am toying with a friction shock design employing some brake lining crammed into the tubes in place of the bearings.

As you might suspect, aero is everything in my mind.

Roofus

when do any of these cars run in clean air?

When you are at the front of the draft pack.:D

If there was a car out there with no steering arms, brake lines, or shocks ...... I think I'd let him lead :)

Good one Greg :D, but I don't think he would lead for very long.

Garry

Thanks for providing the information, this is great!

When you say:

Quote:

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Originally Posted by roofus

My TUNNEL VISION CFD version 6.6.6 tells me that an all enveloping nose, shock tower to shock tower, produces less drag than exposed tubes or individually streamlined tubes.

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Do you just add an envelop at the leading edge of the beam, or do you also add a tail at the back of the beam to produce a NACA airfoil profile (Citation/XTC style)?

Have you studied the use of barge boards installed close to the towers to limit the drag at the back of the front wheels? Same question for rear wheels.
Have you compared the drag produced by a faired roll bar hoop (as seen on Mysterian FVs), compared to a typical 1.375" round tube exposed in the airflow?

Quote:

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Originally Posted by roofus

My TUNNEL VISION CFD version 6.6.6 tells me that an all enveloping nose, shock tower to shock tower, produces less drag than exposed tubes or individually streamlined tubes.

Such a nose also provides more foot room, and space for the ballast needed to obtain that "perfect" 50/50 weight distribution.

The next single best improvement regards less drag at the front end was to leave off the front brake hoses, followed by leaving off the tie rods.

My next effort will be to study replacing the shock actuator rod with a set of 3/32 wire push pull cables. If a suitable system of cable shock operation is not found, I am toying with a friction shock design employing some brake lining crammed into the tubes in place of the bearings.

As you might suspect, aero is everything in my mind.

Roofus

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While you're at it, while installing dzus fasteners.. Is it better to line up the slots parallel or perpendicular to the airflow?

:D

I put tape on my dzus fasters so they don't come loose. I've lost quite a few like this while on the track. None since I use tape.

I guess that fixes the aero issue.

Quote:

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Originally Posted by Tiago Santos

While you're at it, while installing dzus fasteners.. Is it better to line up the slots parallel or perpendicular to the airflow?

:D

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Many years ago Bill Noble took a car to the Kansas State wind tunnel and they confirmed that the wide nose with trailing spats was better than the narrow nose with fairings. The greatest source of drag were the Lynx side scoops. Bill told me that they abandoned some experimental barge boards when they figured the drag offset any aero improvement.

With our tires and suspension pieces hanging out all these little bits of aero don't really add up. Reduce the frontal area as much as possible and try to keep the whole body as smooth as possible. I think:D

It's always interesting to see that good old FV guys pretty much tried anything back in the days.

Thanks for sharing the info.

Quote:

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Originally Posted by budawe

Many years ago Bill Noble took a car to the Kansas State wind tunnel and they confirmed that the wide nose with trailing spats was better than the narrow nose with fairings. The greatest source of drag were the Lynx side scoops. Bill told me that they abandoned some experimental barge boards when they figured the drag offset any aero improvement.

With our tires and suspension pieces hanging out all these little bits of aero don't really add up. Reduce the frontal area as much as possible and try to keep the whole body as smooth as possible. I think:D

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Also, I'm thinking if you need the fairing between the frame and the shock towers for "foot room" you might need to think about a bigger car--like a Top Fuel Dragster.

I believe that having a full fairing allows to use bell cranks for the steering links. This moves the steering arm out in front of the beam, which allows to move the pedals towards the front.
Thus you get more leg room.

This is typical of Citation and XTC cars.

Quote:

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Originally Posted by Garry Sharp

Also, I'm thinking if you need the fairing between the frame and the shock towers for "foot room" you might need to think about a bigger car--like a Top Fuel Dragster.

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you might try those vortex generating butterfly tab dzuses

just saying

Robert (Roofus),

Are you back in Texas or still traveling the world these days?

We'd been using TUNNEL VISION CDF 6.6.6 but gave up finding that software to be too demonic. Instead we bought a used smoke machine off ebay (owner claimed it originally belonged to Foghat then sold to various politicians). We found much better results just blowing smoke at it. :D

It's fun to watch you set those traps and watch'em come running, you still have the touch.

Good to see your still lurking around the boards. Hope all is well with you and yours.

Bill, re-post the link to the Race Car Engineering story.

Dave

Dave,

Don't have the link anymore, besides I doubt it will change any opinions (i.e. posting a link will only fan the flames).

Will I see you at Bob's party?

Dave

Email me and I will send a PDF.

Brian
hardingfv32@verizon.net