Efini~FC3S

iTrader: (4)

Yes, I've wondered the same thing on the splitter/undertray. For fire hazard reasons I'd rather not have just a plain wood undertray.

I might send a note to the regional tech guy asking for clarification.

Leafy

iTrader: (1)

Just spray the wood with gelocat rather than paint. They will never know the difference if you dont tell anyone.

mx5-kiwi

3 mm mdf is not a fire hazard, bends very easily and can be epoxied or just painted...

it's not waterproof without a decent paint and is not the lightest but would work fine, I would think.

1993ka24det

Here is something with a MX5 I haven't seen done it's to help remove hot air from the underbody and the floor of the car.

motormechanic

iTrader: (1)

nice work. Due to the low pressure region behind the car, they will naturally draw air out. That will definitely help smooth the flow of air. Do you have any way of feeding air into it to help speed it up?

Madjak

Heya all, I have been working on a custom 3D printed wing for my car. I don't have to pay for the cost to print since I have a 3D printer so it's just material costs (around $70 for the plastic used). I also wanted to trial a custom wing profile that I found on the NACA site that is designed for a very low drag to downforce ratio. It should suit the tracks I run on without creating massive downforce or requiring a very high speed.

The initial 3D design breakdown:


Print time for each section is around 10 hours, so a total of approx 110 hours of printing. I managed to get nearly 2 completed each day so I printed all sections in a week.

Here is a shot of it in parts getting assembled. The 12 plastic sections slot onto two ally rails that then get clamped at the ends with the brackets that mount the end plates. The main support brackets also slot onto the rails and are keyed into the plastic.



I have yet to test the wing at speed but it all feels pretty solid on the car other than a bit of sideways wobble. I think I might have cut too much metal out of the main vertical supports and will probably make some solid versions instead which should help the overall wing rigidity. The actual 3D parts have an internal honeycomb structure making them very strong but light. All up there is around 1.8kgs of plastic but next time I think I could reduce the infill even more to reduce weight and printing materials required.

The photos below are the first install. I'll add a gurney / wickerbill which is a 10 x 10 mm ally angle and also angle the wing a bit more for my first test.





The endplates are a similar design to what Ryan (ThePass) has made for the COT wing. They are a little smaller and the angles are based on my wing profile so I hope I got the concept correct. Thanks Ryan for inspiring me to develop DIY aero!

emilio700

iTrader: (3)

Yikes. What does that entire assembly weigh without the uprights?

Madjak

I haven't weighted it yet but it's very light. I could easily hold it in position with one hand whilst drilling the mounting holes in the boot. I think the ally would be 2kgs so around 3.5kgs total. I'm not that calibrated to weight so I'd have to weight it properly to know.

For reference, how heavy are the APR GT250 wings?

emilio700

iTrader: (3)

The FRP version we sold was about 4.2kg with end plates and lower brackets.

Madjak

Mine must be heavier than that then. I'll weigh it properly tonight. I'm not sure on the internal construction on the APR wing but the two main backbone ribs are the heaviest items on my wing. The plastic itself is very light and could be lighter again I think. My main supports are also very light, a little too light I think, might end up like this:

motormechanic

iTrader: (1)

that looks like a COT profile. Especially with the Singular endplates.

Madjak

The COT wing has a much more aggressive convex (EDIT: CONCAVE not convex) curve on the bottom trailing edge. The leading edge is also lifted a little on mine so that the top surface is a simpler curve, but the bottom is a longer edge. The total thickness of the wing is reduced as well as it's chord length.

I have my CAD profiles somewhere and can load up the NACA profile vs the COT profile vs mine... I've just had a computer rebuild so I'll have to retrieve them off my old drive.

Does anyone have a photo of the APR GT250 wing without endplates? I think my wing should be pretty close to that design. I was looking for one when designing the profile and I don't think I ever found one.

mx5-kiwi

Is everyone seeing the images Madjak posted?

Madjak

They are hosted on Box.com (similar to dropbox) with a public share. I need to get my act together and register for an online photo host. Maybe you have a firewall that blocking your access.

EDIT: Uploaded the images to a photo site and they should now work better... I hope

sixshooter

iTrader: (12)

Use small gauge cables and turnbuckles crossing in the middle like light airplanes use to add rigidity without much weight or drag.

emilio700

iTrader: (3)

Cables have massive drag/turbulence relative to their frontal area. If the uprights need to be braced, locate all hardware below the trunk, not up in the air stream. On most of the Crusher style mounts I've seen, any of the flex present can be seen right at the turn where the uprights leave the tub. Crushers brace was an old Integra STB cut down and repurposed, located at the very bottom of the uprights. Went from wobbly to rock solid with virtually no drag penalty.

aidandj

iTrader: (5)

Excited to clog up my work printer for the next week or so

vehicular

iTrader: (3)

How stiff is the wing element? I wouldn't think that it would be stiff enough not to deform/ disintegrate at speed.

aidandj

iTrader: (5)

It has aluminum tubing running through it horizontally, so I bet its pretty stiff.

vehicular

iTrader: (3)

If you layed those two aluminum tubes across the uprights and put a 300lb distributed load on them, they would deform dramatically. That's exactly what you're doing at 120mph. Likely more force, actually.