awfulwaffle Posted September 26, 2020 Share Posted September 26, 2020 60 mph wagon butt, no spoiler. Drag: 157 N/ 35.3 lb Lift: 476.2N/ 107.1 lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 26, 2020 Share Posted September 26, 2020 100 mph wagon butt, no spoiler. Drag: 409 N/92 lb Lift: 1136 N/255 lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Interesting takeaway, our factory wings do seem to have some effect in reducing lift generated by the wagon body. Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 With spoiler: 60 mph run returns 155.4 N/34.9 lb of drag and 414.1 N/ 93.1 lb of lift. 100 mph run returns 406.2 N/ 91.3 lb of drag and 915.5 N/ 205.8 lb of lift w/out spoiler: 60 mph run returns Drag: 157 N/ 35.3 lb, Lift: 476.2N/ 107.1 lb 100 mph run returns Drag: 409 N/92 lb, Lift: 1136 N/255 lb wonder what happens if the rear wing is 6 inches longer? foot longer? higher above roof line? Rules for ST allow the wing to be upto 7 inches above roof line and as far forward as centerline of rear wheel. Height restriction on rear wings too, but can be upto 36" behind car. Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 100 mph wagon butt, no spoiler. Drag: 409 N/92 lb Lift: 1136 N/255 lb Wonder what a rear diffuser would do here? Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
Nonamedude Posted September 27, 2020 Share Posted September 27, 2020 Wow that changes the lift quite a bit. Pretty crazy, I wouldn't have expected that. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 Yeah I was surprised too. Guess Ill put it back on. Although I'm curious if moving the wing or adding different front splitter with rear diffuser would help. Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
Nonamedude Posted September 27, 2020 Share Posted September 27, 2020 I really want hood vents. So I'm curious to that. But I guess I don't want hood vents bad enough to learn cad. I've got about. Idk. 3k photos to go through from the last few events. Maybe when I'm done sorting and editing those I'll start looking back into cad again. I have more access to a computer now so maybe it'll go smoother. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 hood vents only work if ducted air goes through them, otherwise waste of space Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Mocked up rear diffuser, 100 mph. Drag force: 413.2N/ 92.9 lb Lift force: 1021.6N/ 229.7 lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Mocked up rear diffuser, 60 mph. Drag force: 159.2N/ 35.8 lb Lift force: 438.2N/ 98.5 lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Mocked up splitter, 100 mph. Drag force: 420.7N/ 94.6 lb Lift force: 1166.4N/ 262.2 lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Mocked up splitter, 60 mph. Drag force: 161.4N/ 36.3 lb Lift force: 473.2N/ 106.4 lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 (edited) Mocked up dam, 100 mph. Drag force: 409.4N/ 92.0lb Lift force: 1345.7N/ 302.5lb Edited September 27, 2020 by awfulwaffle Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Mocked up dam, 60 mph. Drag force: 157.2N/ 35.3lb Lift force: 518.7N/ 116.6lb Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 These were just eyeballed geometries, so I think next it makes sense to do a sensitivity study in terms of length/position of the diffuser/splitter/dam/ride height, and check out some combinations of components. Let me know any thoughts on this. One fun thought I had - I could parameterize this model so the CAD automatically regenerated based on external inputs of some geometric parameters. Could then feed this to a design space exploration software, which would build a response surface in terms of drag and lift. We could then have a neat little Python module that you could input your diffuser/splitter/dam geometry and ride height, and it'd return the corresponding lift and drag. This would take a bit of effort to set up, but once that's done I think I could push through 1000 runs to base the response surface on in a weekend. There'd be no visuals to go along with those points unless we wanted to pick some to run individually afterwards, though. Thoughts? Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Pretty curious that all the first whack 'improvements' seem to underperform a factory wagon cross-section at stock ride height. Need to spend some time noodling on this later. Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 Pretty curious that all the first whack 'improvements' seem to underperform a factory wagon cross-section at stock ride height. Need to spend some time noodling on this later. Kind of makes you wonder about all those mods the aftermarket has convinced 'you' to buy? Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 (edited) These were just eyeballed geometries, so I think next it makes sense to do a sensitivity study in terms of length/position of the diffuser/splitter/dam/ride height, and check out some combinations of components. Let me know any thoughts on this. One fun thought I had - I could parameterize this model so the CAD automatically regenerated based on external inputs of some geometric parameters. Could then feed this to a design space exploration software, which would build a response surface in terms of drag and lift. We could then have a neat little Python module that you could input your diffuser/splitter/dam geometry and ride height, and it'd return the corresponding lift and drag. This would take a bit of effort to set up, but once that's done I think I could push through 1000 runs to base the response surface on in a weekend. There'd be no visuals to go along with those points unless we wanted to pick some to run individually afterwards, though. Thoughts? Uhm, you can do this? Omg. yes. Didn't even know this was possible. Can it run parameters until it finds a negative lift solution or a lift that was less than stock? then flag it to run as an individual picture run? Edited September 27, 2020 by boxkita Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Yup, can do that too. Would just run the parameterized model through an optimizer that seeks either maximum downforce, minimum drag, or a compromise between the two. I'll get going on the CAD stuff when I get a chance, but could use some help on what to parameterize. Things like splitter/wing/diffuser length height and angle along with ride height seem to make sense. Anything else worth including? Link to comment Share on other sites More sharing options...
awfulwaffle Posted September 27, 2020 Share Posted September 27, 2020 Kind of makes you wonder about all those mods the aftermarket has convinced 'you' to buy? Definitely. Also makes me wonder what we might be missing with the 2D solution, though. Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 Definitely. Also makes me wonder what we might be missing with the 2D solution, though. sent you a pm. At one point, I was a fair-to-middling programmer of obscure languages. Never learned python, but for this, I'm willing to learn. The 2d seems a bit off to me. The front nose actually has a bit of hook under the front bumper, while the rear is really flat without the knob sticking out. Can you share the 2d model you created? Or it in a special cad software only format? Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
boxkita Posted September 27, 2020 Author Share Posted September 27, 2020 Yup, can do that too. Would just run the parameterized model through an optimizer that seeks either maximum downforce, minimum drag, or a compromise between the two. I'll get going on the CAD stuff when I get a chance, but could use some help on what to parameterize. Things like splitter/wing/diffuser length height and angle along with ride height seem to make sense. Anything else worth including? smoothing rear window to make it more flat, like audi does with their wagons? Madrig was willing to make a full tailgate if I could get the design to him. Figuring out how to cure the suction effect at the rear? The dragon of drag Mounting a wing in the middle of the curl off the rear? Supposedly that's why f1 wings sit where they do... to gather air from over & under the car and redirect. Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
jaylew Posted September 27, 2020 Share Posted September 27, 2020 This is awesome. I am definitely interested in making the rear underside more flat near the subframe and exhaust. I know some Python if you need any help. It has been about 3 years since I have done anything intricate in Python but I am sure I could dust off a little. I am getting married in a week so I will be useless for the next two (honeymoon)...then I am back to serious wagon work! Wagon is LIFE! - 265,000 miles and climbing Unofficial Build (Restoration) Thread Steering Rack Rebuild Link to comment Share on other sites More sharing options...
jaylew Posted September 27, 2020 Share Posted September 27, 2020 60 mph wagon butt, no spoiler. Drag: 157 N/ 35.3 lb Lift: 476.2N/ 107.1 lb I am interested to see a marginally longer wing as well (and maybe stupid long wing). Makes me think of the tail end of drag cars, how they extend the trunk lid with sharp fencing on the edge Wagon is LIFE! - 265,000 miles and climbing Unofficial Build (Restoration) Thread Steering Rack Rebuild Link to comment Share on other sites More sharing options...
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