Chassis mounting wing

[JMortensen]

I mocked it up, and it raised the wing element about 1" was really surprised that it was only worth 1". Going to try again with the slot in the back instead of the front, see if it changes things.

[JMortensen]

I was sick, then out of town, then sick again, then out of town again, then sick again, but I'm finally back on the wing. Decided to save myself some pain and bought the 9 lives second element rather than making one.
 

Was hoping that the end plates would have holes that lined up in the right spot. It did. One hole was correct. Verified the overlap and gap per guidelines in Competition Car Aerodynamics, and drilled the rest of the holes. Here's what it looks like on the floor.
 

I need to get the holes cut in the body and the mounting brackets built. I think I'm going to make the uprights from wood before I cut the aluminum. I have it all traced out, but it's expensive, so want to be sure before I do the final version.
 

This is the flap in its steepest AoA. It's pretty steep. Thinking separation might be an issue. I do have some angle to make a gurney if I need it, and there are 3 other (slightly) less aggressive settings. Thinking for autox just go for broke.

[Fridge Gnome]

Any chance you could measure the chord on the 9 lives second element? I'm now working on a carbon/foam core wing for autox mainly and layup went poorly on the second element so I'm thinking I may just give in and buy that part if its around the right size.

 

Looking forward to seeing your mounting, I've yet to mock anything up there.

[JMortensen]

2.5" and got one of the profile too:

 

[JMortensen]

Just FYI it was about $90 to ship, so factor that in when you're looking at the price online. I ship doggy doors for sliding glass doors that are long like this, they're not gouging. UPS and FedEx just bend you over when you ship such a long box. Plus there is a second package with the end plates. 

[Fridge Gnome]

Perfect, thanks! Also, it sounds like you already have the aluminum, but I pulled the trigger on these uprights from sendcutsend yesterday and it was still only $100 for the two in 1/4" 6061. I thought it was worth it to not have to gum my way through the aluminum and its about the same price as the plate.

 

[JMortensen]

Wow, that would have been a good option. 

[Ben280]

Send cut send is great for just about everything. I've not found anything they aren't good at yet. 

 

Here's my wing mount, I use the same mount concept that Jon is talking about, but I go further down and bolt through to the rear chassis rails. Helps to not have a fuel tank, but I think you could make this work. with anything back there.

 

Here's where the mount ends, there are now 2 3/8" bolts here. 

 

Shot passing through the floor. 

 

Final shape. Rests on the deck lid, but there are also 3 bolts into the hatch lip.

 

I should note, this is NOT SCCA legal, they have a rule about the wing not extending behind the rear of the car. I think that looks stupid, and it means you can't put the wing in the most aerodynamically efficient position. Oh well!

 

Edited May 24, 2023 by Ben280

[JMortensen]

Very interesting Ben. Would have been nice to see before I bought the aluminum for the uprights. Oh well.

Mine won't be SCCA legal either. Figure if that becomes an issue I can make another set of uprights. Just finished my tube frames to transfer load to the floor.

Yours is no doubt stronger. The advantage to mine is that I'll be able to drill several sets of holes in the uprights and raise and lower the wing. 

Been doing a little research and the trend seems to be to want to get the elements down to roof level to reduce drag even in time attack cars that generally don't care about drag. I'll experiment a bit I guess. The other thing I'm curious about is the spoiler. Leave it 10" and lay it way down, or make one that is closer to 4" and keep it relatively upright? Thinking I might get more diffuser action if I lay it flat. Of course, would help to have a diffuser. Haven't made any progress on that one... typical.

Edited May 24, 2023 by JMortensen

[Ben280]

If I were on this forum more often you'd have seen the photo! Sorry for holding out on you. 

 

Generally when I see a rulebook say you can have one or the other, it means that both is a solid combo. Looking at some of the big name TA cars out there, they are doing a long "duck bill" or "whale tail" situation. I think laying the spoiler down would help accelerate airflow under the wing, or it might just help reduce drag. Either way, if you have the ability, I say go for it!

 

Talking with the guys who designed my wing, they said roof level was just about perfect. Too much higher and you run into stability issues, with no real performance gain.

[JMortensen]

I think the reason the whale tail works is that it lengthens the car and the flow tries to stay attached longer, and this reduces some of the ill effects of air from underneath losing contact and becoming turbulent, and also redirects the air coming off of the top, which would otherwise be traveling down and creating lift. I think this is why the drag racing spoilers work too. I've wanted to see wind tunnel/CFD data on this forever.

The one think that I think might be an issue is that if the tail is TOO long it might insulate the wing's upwash from the bottom of the car. I think you want the wing to pull air out from underneath, especially if you have undercar aero, but since we both have (or will have) wings hanging off the back a ways, makes sense that the spoiler can be a little longer. 

Spoiler angle and length with wing is definitely something worth testing.