I need to brainstorm ideas for a lightweight front wing that can survive a cone hit.
Any A-Mod people here?
I need to brainstorm ideas for a lightweight front wing that can survive a cone hit.
Use what we used to call a "sports car nose" with a really robust splitter. (like 1/2" plywood)
I don't know what that is.Originally Posted by Purple Frog
Use what we used to call a "sports car nose" with a really robust splitter. (like 1/2" plywood)
Here's some more background. The rear wing is huge, and I already have aero push. Secondly, our venue is rough and narrow, so SCCA style courses are not possible. Thus, smacking cones is unavoidable.
I'm no expert, but I went through a similar exercise on my BM wing a few years ago and have been very satisfied with the durability of the result. After rebuilding the wing 3-4 times from cone hits (cones are much stiffer in our 50 degree spring/fall events than the Texas events with the original owner), I decided it was time to rebuild/redesign it to make it more durable. Happy to share my experience.
Sports car nose looks like https://www.apexspeed.com/forums/sho...l=1#post199056
Downside is a sports car nose, while more durable, will not give you as much downforce as a proper multilevel wing.
Autox_vette, care to give details of the wing construction? I feel there may be foam core with carbon fiber and lots of Kevlar involved to be able to take a hit from a baseball bat.
We managed to punch a big hole in our carbon splitter with one good smack of a cone dead center at our first event.
We expect that when we rebuild it, we will do an aluminum strip on the leading edge and that should be enough to protect it from cone impacts - not yet tested, just expected...
-Mark
Mark Uhlmann
Vancouver, Canada
'12 Stohr WF1
Honestly I don't think you can protect any cars body work against hitting a cone at 70 + mph. In my humbled pinion, if you want to have your body work survive hitting a cone, don't hit cones ? but you then tend to give cones lots of space which is time.
For me if I had a car with F wings I would think about having F wings replaceable in less than 5 mins, so make F wings that work in the cost to staying together at speed and at everyday autocross events so on the rare occasion's that you do hit a cone "easy fix", to paying big money for a wing that is hard to replace or easy?, could weigh more and then still not survive a cone hit?.
In 30 years of autocrossing I've seen valve stems ripped off, Lots and lots of everyday daily drivers type cars body work be ripped off and yes F wings in all type of breakage and lately inner fender liners, In closing I've never seen any car/body work survive a cone hit with no damage.
Ben
Now in fairness, Phil basically center punched this cone at 60mph+ so pretty much "worst-case scenario" but regardless... not pretty.
-Mark
Mark Uhlmann
Vancouver, Canada
'12 Stohr WF1
Yes, please. Particularly that double leading edge you have going on there.I'm no expert, but I went through a similar exercise on my BM wing a few years ago and have been very satisfied with the durability of the result. After rebuilding the wing 3-4 times from cone hits (cones are much stiffer in our 50 degree spring/fall events than the Texas events with the original owner), I decided it was time to rebuild/redesign it to make it more durable. Happy to share my experience.
The front element is an aero device called a slat which is used to increase downforce. As you can imagine, it is also the primary element that takes the abuse from hitting cones.
This is probably going to get long, but I'll try to share everything I learned in the redesign/rebuilding of my wing...
Being an engineer I spent a lot of time analyzing the failure mode of my old wing and attempting to (over?) engineer a solution which takes those into account. My original wings were (I believe) 2 coats of fiberglass over foam cores with aluminum end bulkheads and 2 mounting bulkheads embedded into the middle of the main element. There were no spars running lengthwise of the wing, so there was nothing other than the thin fiberglass skin to transmit the energy of a cone hit through to the wing to the end plates through what little resin bonding occurred to the edges of the Al end bulkheads. This typically caused the end bukheads to pull out of the wing leaving the element unsupported, pulled more end bulkheads from other elements, and causing a cascade destruction of the wing. So, my main focus was designing a support structure that would fit inside the wing that would absorb, transmit, and dissipate the energy of a cone hit.
As the previous poster guessed, it is kevlar over foam cores, but there is a lot more going on inside the elements. All of the elements have a solid carbon fiber pultruded rod running through the middle of the wing as a spar (.5" in the main, .375" in all others). The slat and the main element, have an additional bulkhead 6" from each end tied together with .25" Al rods (2 in the main, 1 in the slat) which the bolts in the end plates screw into. The flaps have only end bulkheads. The wing is designed in 3 identical sections which bolt together using the plates used to mount the wing to the car. This way I only have to make 1 spare element of each element and it can be replaced quickly (I haven't made the spares yet, but that's the plan), if one gets damaged. An additional benefit of the 3 section design is that I can take partial elements out to tune the amount of downforce being generated. In BM we're limited on the height and size of our rear wings, and I have been having problems getting a good aero balance, but I have figured out that taking out the top center element helped a lot.
I made the wing with a wet layup vacuum bag technique. They specific layup for each element was determined based upon the location of the element. The slat is 3 layers of kevlar with 1 layer of CF (mostly for UV protection and to match the other elements). The main is 2 layers of kevlar with 2 layers of CF. The flaps are 4 layers of CF. The kevlar I used is a 5 direction weave to better handle the many axis of forces that the wing could see.
The disadvantage of all this reinforcement is that it's heavy. It weighs around 27lbs, but it has taken several direct hits in cold weather with no signs of damage (the Al end plates have taken some damage), but I met my goal of making it so that I don't have to worry about hitting cones. I have impailed cones and drug them through the entire course.
You can probably see in the picture that there's some texture in the surface of the elements from the vacuum bagging materials (breather cloth), and there are some irregularities where I had to cut the cores to insert the additional bulkheads and support rods, so it's not perfect, but it seems to work quite well. I'm planning to work on smoothing the surface of the elements this winter to increase the performance of the elements. I also have to remake my rear wing using the same techniques (no kevlar, no additional bulkheads, and only 2 layers CF).
Hopefully I was able to write this so that you can figure out what I mean without actually seeing it...Unfortunately, I didn't take any pics as I was building it.
Kenton
Thanks very much. I like the idea of replaceable, and possibly identical elements.
My only other thought so far is to make the wing far enough above the ground to go over cones, but there are several problems with that.
Slide your rear wing forward.
Many years ago I made carbon fiber bits for sport bikes.
My resin manufacturer told me that epoxy resin can be annealed post cure. The result is a piece that is less brittle.
If my memory is correct the process is to slowly increase the temperature to a specific point over a 12 hour period, then a 12 hour cool down.
Try a web search on annealing epoxy resin.
Thanks, but I don't think that would help much. I made a wing in Autocad that was high enough to pass over the little cones we use, and it ended up being 3 feet high! Not going to be able to see over that!
I am going to move it about an inch, beyond that, I would have to build a whole new wing, since it's all glued together, no fasteners at all. The wing elements slid into the aluminum uprights that were water jet cut to match.
haha, welcome to A-Mod. It won't be the last time you build something four times.
You can also move the front wing forward. Hard to see exactly how close it is in your photos, but it looks close. Get it out front in clean air. Spinning tires do horrible things to air flow.
This is my second A-Mod car, so I know all about iterations. The first car took me 3 seasons to get to FTD, this car, I just about went from slowest guy to fastest in 1 season. New tires should be all it takes to get there. The current wing is temporary, not very effective.
The car in the picture is what I can not do. His front wing cost more than my whole car, and I would destroy it in no time. Our site is a runway. Slalom, slalom, slalom, 180 turn, slalom, slalom, slalom. Maybe a Chicago box. Also very rough pavement. You can't avoid hitting cones.
One thing I did with the old car was to put thin sacrificial extensions on the endplates held on with screws. They would crumple if you hit them. That worked well.
It did just occur to me that if I could move the rear wing forward, and make it even bigger, I could have less front wing, which might make things easier. Hmmmmmm.
Last edited by Onebadbug; 12.01.19 at 5:31 PM.
I wasn’t suggesting you buy the wings I had on my old car. I was suggesting you move it forward. FWIW, those wings took many hard cone hits at 75+mph. What finally broke was the wing mount itself. However, this is your second A-Mod car, so clearly you’ve got it figured out.
Lol... sometimes can't help, no matter how hard you try...
-Mark
Mark Uhlmann
Vancouver, Canada
'12 Stohr WF1
The Dauntless wings on KJ’s old car were something like 15 or more layers of carbon fiber, hollow core with internal carbon structure. I hit many cones with them and they liked it.
carbon monocoques can survive CAR strikes, cones are no big deal if you do it right.
Just curious. If you have aero imbalance causing push... why not move the massive rear wing forward (like over the driver)? Like sprint cars or WOO...
It would then require less front wing.
I remember a hillclimb championship car back around 1999 that had the wing mounted over the driver.
My car back in the 70s had a front splitter made out of thick aircraft aluminum ahead of the aero. If i hit a cone it sliced it off like cheese. Bought a few cones for the local club.
Thank you. Maybe I will do some destructive testing.
The current wing is already too tall, and because I am a giant, having it above my head isn't practical.Just curious. If you have aero imbalance causing push... why not move the massive rear wing forward (like over the driver)? Like sprint cars or WOO...
It would then require less front wing.
I remember a hillclimb championship car back around 1999 that had the wing mounted over the driver.
My car back in the 70s had a front splitter made out of thick aircraft aluminum ahead of the aero. If i hit a cone it sliced it off like cheese. Bought a few cones for the local club.
I have been thinking about the "slicer" option!
Thanks for the ideas.
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