Let's talk about winglets and canards

[HeatRaveR]

For my own reasons, I can/will not further lower or extend the stock airdam on my 280ZX Turbo, but I would like to explore other ways to assist with front downforce (particularly since I have the ZXR wing on the back). The only things I can think of that wouldn't lower or extend the front lip are winglets and canards, which are frequently seen on modern Touring and GT race cars. So I'd like to get some feedback on which might be more effective for the shape of my front airdam, particularly since the factory airdam doesn't entirely block off the front wheels. I'm more concerned with effectiveness than whether or not it looks "right" on an old Z. Of course, if you have other (practical) ideas for increasing high-speed stability that doesn't lower/extend the front lip, I'd love to hear them.

 

For picture ID purposes, the green Takata NSX is to show winglets, while the blue Wedsport Celica is to show canards. And then the following pairs of pictures are for some cardboard mockups of each, just to give an idea of how they would alter my front bumper.

[260DET]

You want to do things the hard way don't you, working off the original front instead of replacing it with a decent aftermarket airdam

 

Anyway the first thing I would do is put deflectors either side to cover the front view of the tyres. They could be made from pieces of aluminium sheet and should reduce drag and improve air extraction through the wheels.

[HeatRaveR]

How thick do you reckon I'll need to make the front-wheel-deflectors, in order to stand up to 120mph without permanently bending? Currently, I'm using some ABS pieces in a similar fashion for the rear wheels, as seen in the attached pic. Do you think this will be sufficiently thick/rigid enough for duty on the front wheels?

[ZR8ED]

Well I have built my front belly pan, and rear diffusers from aluminum, and have seen no deformation of the materials from air/wind pressures. Mine are approx equivilant to 22 guage (aluminum is in mils and I don't recall the actual number)

Out at the front of the car in the direct path of air, 16-18 gauge thickness would be more than enough. The only deformation you could get would be the bending of the metal that it is attached to, so proper supporting of the add on metal would be neccessary. If you want it body coloured, I would use steel, if you like the "bolt on race look", I would go with aluminum. With the right bracing/curves etc, you could probably build it from 20-22 gauge metal.

 

Use bristolboard to build your templates to get the design and fit just right. More rigid than paper, more flexible than cardboard.

 

I look forward to hearing about trials..even if they are seat of the pants. Ie I know for sure that at 155mph my front belly pan helps, and that the rear diffuser didn't cause any noticeable negative or positive results. (At least it didn't cause the car to fly away like some feared..)

 

Goodluck!

[260DET]

I'll be using ~1.3mm thick alumimium to make an undertray, may get it ribbed, with proper support that should be OK. For smaller items that thickness should be all you need providing the items are properly attached.

[HeatRaveR]

Well I have built my front belly pan, and rear diffusers from aluminum, and have seen no deformation of the materials from air/wind pressures.

 

How far back does your belly pan go? I'd heard that our engine bays are "bottom-breathers", so I was worried about blocking off pathways that hot air escapes from.

[Gollum]

If you added side fender vents like the SDI car in the testing, and had hood vents, I don't think blocking off the bottom of the engine bay is a problem.

 

Study the test data and don't take it all for face value, and really think about WHY the numbers are what they are.

 

The front always experienced more lift than the rear. The test that it was the lowest in all had a patter... The front was blocked off. Now, why would the air going into the front of the car be creating lift? Solve that mystery and you can start designing around the solution.

 

Personally I don't know excatly why, and I'm sure other people's guesses are better than mine, but I'll share what I've concluded on my own.

 

#1 reason I think we're seeing such huge lift from the front openings is that the openings are behind the leading edge of the front. So what you end up with is a huge ball of air that can't get over the hood and only has one place to go, down. This force of going downwards creates lift.

 

#2 reason, I think is that the openings let more air under the car to begin with, and the undercarriage isn't well suited to having air down there. Notice how just minor taping on the tests had quite beneficial results.

 

So I think one of the main questions to answer is "where is the air in the front pushing up? Before the core support? Or after? I really want to say before, because that makes sense seeing as air can only pass through the radiator around 15mph, so the blockage is there and air can't get past.

 

But we've all see videos or experienced it in person, that a fiberglass hood will bend in the middle and let air out, showing that there's huge amounts of air in the engine bay trying to come UP.

 

Will these problems dissapear when the front core support is completely sealed up so air can only get by via the radiator? Will creating a box so the opening air can only flow to and throuth the radiator have the same effect?

 

Many of these things I'm not sure of at all, and they're questions for a reason. But I really think if you figure out how to route the air comming in, and not let any excess air through the front end, you can do whatever you want practically with blocking off the belly, just as long as the air can get out via hood vents or other vents.

[ZR8ED]

My front belly pan goes all the way to the crossmember, and has the minimum cut out for the wheels to turn and move.

 

I found even with the belly pan, that my hood would flutter slightly, and it would flutter way up at the front, at the rad support.

 

I then boxed in the front of the car. ( I have pics in other aero threads where we talk specifically about the front rad opening) After this, the flutter when completely away.

I do not have any overheating issues, and I have been using this belly pan for almost 10 years. The front end mods were made last year following the results of the aero testing data.

[Gollum]

I remember seeing your modifications, and I remember them looking pretty good. (I've been going through that thread again, toying with ideas of doing my own air box)

 

Thanks for the input regarding the hood flutter. So this to me suggests that most of the air in the engine bay IS just comming from the core support, and quite a bit of lift is being created from all the air trying to get through.

 

But back to the topic that got us talking about air boxes, belly pans. Heatraver had been told that S130 cars are "bottom breathers" and that closing off the bottom would be a bad idea. Personally I don't see why this would be a problem. Even if you made a belly pan that went all the way to the firewall you'd still have air able to escape through the transmission tunnel.

 

Engines are cooled by radiators, not air. As long as air keeps flowing through the radiator you're fine.

[johnc]

Winglets are flow control devices and don't, by themselves, generate any downforce. Canards do generate downforce but usually in single digit numbers.

[Challenger]

 

Heres what Ive got so far and Im looking at making some "wheel blockers". Any ideas on a shape/mounting points? (notice just mockup, not finished)

[HeatRaveR]

Regarding the custom airboxes around the radiator, I don't know if that would still apply the same way for the S130 since the front end/inlet is different. The 280ZX does have some big ol' hood vents, but I don't know how effective they are at relieving underhood air pressure while moving, especially since one of them is integrated with a NACA duct to bring air *into* the engine bay and over the turbo.

 

I did install some custom side vents in the front fenders, but with my car, I couldn't find a convenient place back there to make an opening to connect to the engine bay without removing the wheel well splashguard. Any opening I cut back there would be too close to, or behind, the firewall and/or have airflow impeded by being behind the turbo heat shield (left side) or under the battery mounting (right side)

[(goldfish)]

the boxes for the radiator still work and help the s130's.

 

Do you not want to replace your airdamn with an aftermarket? I think that's the best option for now.

[Tony D]

Don't mix S30 and S130 in the same thread, you guys will muck it up for sure!

The NACA duct on the S130 hood, BTW is dual purpose. During high speed driving the duct lets air in, and through a channel acrtoss the hot isde of the turbo---it's a high to low pressure flow path.

When at low speed, the VENTED AREA BEHIND the NACA Duct allows turbo heat to simply convect UPWARDS through the hood. It's a dual-purpose opening.

 

Same as underbelly pans. The S30 stock pan went from the lower radiator support structure back to almost the transmission mounting member, with the left side cut out to accomodate headers and large exhaust used on the Z432.

[Daeron]

You do not need a smooth, easy transition for air out of your engine bay like you need smooth, easy transitions into your intake port.

 

The problem with lift and air under the hood is one of high pressure. Provide that higher pressure air with a vent-hole to a lower-pressure area, and it will move around whatever seems to be in the way... and with less pressure under the hood, it will make it easier for fresh, cool air to flow through the radiator.