Seeing ianscrawford’s post back in June on his homegrown aluminum wing got me thinking about the real possibility of building a foam composite carbon fiber wing. Having mis-spent my youth as a beach rat in Encinitas, CA building skateboards and surfboards, I figured it couldn’t be too difficult. So the research began (it’s nice having free time with kids in college). What I found was that it’s not all that different and can definitely be done in the confines of the average garage (obviously, the more cool tools you have the better, but isn’t that always the case).
So during my research, I found that Aircraft Spruce was about the best source and the closest to having experience in what I was attempting to do (building wings). Fortunately, AC Spruce also has their east coast facility about an hour away in Peachtree City, GA.
So I began by picking up a big block of large cell polystyrene foam. Shipping on this will be about as much as the cost of the foam, so I went to their shop and picked it up (I did make the mistake of driving my M5…you should’ve seen me wrestling this 70”x16”x8” block of foam into the car!). I also figured I could take the opportunity to ask questions and see the other materials that I would be using on this build.
The next thing I had to figure out was how best to cut this big piece of foam. A little more research and I put together a hotwire cutter. Actually, I made two. One to cut the ends of the foam to get a true edge and a larger one to shape the foam out of the block.
Cutting the foam 1.jpg
You want to use thicker .032 Inconel wire that’s made for this application due to the span compared to most of the hotwire setups. You’ll need at least 4 amps to power this wire with enough heat. I used a 5 amp transformer with 4 amp inline fuse. Directions for the hotwire cutter are on this link: http://www.utahflyers.org/index.php?option=com_content&task=view&id=37&Itemi d=33
Hotwire transformer.jpg
With the hotwire cutter ready to go and the block of foam in the garage, I needed to decide on the shape of the wing. I did quite a bit of research online and looked at various designs. With a cursory understanding of aerodynamics from my college days, I knew I wanted a wing with good lift to drag characteristics. Most of the wings offered seemed to be high lift but also high drag type airfoils. In the end I decided on a more conventional shape with a slight up kick to resemble moderate flaps. Will my design work? I’ll have to wait and see…but this is part of the fun of building it yourself….experimentation!
Once I had a design, I cut out the hotwire templates from some 3/8” “hobby” pine from Lowes. To this I aluminum taped some of the cutting wire to allow for over melting of the final shape. This turned out work perfectly. I held these in place on the foam with simple nails. These templates will also be used to bond to the ends of the foam to allow attachment of the aluminum end plates.
Cut template.jpg
When hotwiring, the key is to go slow…very slow. The hot wire will stretch if you force it. You also need to make sure your templates are aligned correctly so your wing doesn’t have any twist. I’m not good at taking pictures as I go, so I didn’t get any pictures of the process, but here is the finished cut with the cutter. You should get 6 blanks from this piece of foam…I got three due to experimentation (and mistakes).
Cutting the foam 3.jpg
With the wing cut out you then finish shape this with open weave sandpaper.
Foam sanding paper.jpg
To prepare the foam for the epoxy, you need to cover it with Superfil. I gave this a final sanding before proceeding.
https://photos.smugmug.com/Wing-M3/W...uperfill-L.jpg
To mount the wing when complete, I bonded some aluminum to the underside to go under the carbon fiber. This will be the backing that I’ll rivet the mounting bracket to when mounting to the car.
https://photos.smugmug.com/Wing-M3/W...20plates-L.jpg
Now it’s time for carbon fiber. I decided on three layers. One thinner unidirectional layer with the threads running the span of the wing and two layers of heavier plain weave. Cut the fabric to rough dimensions, making sure to tape the edges as this stuff unravels really fast.
https://photos.smugmug.com/Wing-M3/Wing/i-XBKtr7k/0/1575e597/L/Cutting%20Carbon%20Fiber-L.jpg
And now it’s show time…time to epoxy some carbon fiber. Before you begin you may want to watch some video and read as much as you can on techniques. The video link below is an excellent source for a how to:
[ame="http://video.google.com/videoplay?docid=8801536764731290932"]http://video.google.com/videoplay?docid=8801536764731290932#[/ame]
You’ll definitely want a helper with this part of the process. It really isn’t difficult as long as you take your time and plan it out before you begin. Use the slow curing hardener from West Systems and you should have plenty of time to work the epoxy into the carbon fiber. Since epoxy cures, not dries, more heat will cause shorter cure times. Unfortunately again no pictures of this process, but here is the finished layup with the course finish on the carbon fiber. One key tip is to trim the edges after the epoxy has set up about an hour. Too soon and it’s gooey and won’t slice. Too late and it’s set up and you’ll have to grind the excess off.
https://photos.smugmug.com/Wing-M3/Wing/i-2JKNzMw/0/b4cdec54/L/CF%20layup-L.jpg
Once the carbon fiber is laid up, you’ll want to let it cure. More heat is better and since this was done in the hot Atlanta summer, I used the track car as the make shift oven. I parked the car in the street with the windows in and saw temps of 130 for about 7 hours. After this the wing was hard as a rock.
https://photos.smugmug.com/Wing-M3/W...wing%202-L.jpg
Next you need to put a coat of epoxy over the weave to get that deep look and smooth finish. I tried a couple of methods. Brushing on the epoxy created runs. Rolling on the epoxy created bubbles. So a combination seems to be best. Roll on the epoxy nice and thin and brush out the bubbles. Also note the jig I made to hold the wing for lay up and finish coating. The wing was held to the end plates with screws and left about a 1.5” gap to the ends of the wing.
https://photos.smugmug.com/Wing-M3/W...y%20coat-L.jpg
After a couple coats of epoxy, you’ll need to finish sand the wing. I found wet sanding to be the best option here as it cuts down on epoxy dust and gives you a nice finish. If you have irregularities, now is the time to fill with epoxy and re-sand. Start with course sandpaper and work up to 1000 grit.
https://photos.smugmug.com/Wing-M3/Wing/i-Z4WMq2F/0/2a7080c3/L/Wet%20sanding%201-L.jpg
With the surface prepared to my satisfaction, I then put three coats of marine spar varnish to give a mirror finish and provide UV protection. I used Minwax Helmsman spar urethane in oil base available at hardware stores. The finish came out very nice and just a little over 5 lbs.
https://photos.smugmug.com/Wing-M3/Wing/i-mtBwsFm/0/1869e7b3/L/Wing%20jig%202-L.jpg
https://photos.smugmug.com/Wing-M3/W...L/Weight-L.jpg
With the wing finished it was time to mount it to the car. First I mocked up the position, 2” back from the bumper and roof line height per Prepared rules. I used my garage door as the guide, positioning the car 2” from the door.
https://photos.smugmug.com/Wing-M3/Wing/i-SdTmRbf/0/1a0ca270/L/Foam%20Composite%20Wing%20016-L.jpg
As for making the aluminum mounting bits and end plates, that’s all pretty straight forward. I used a bandsaw to do the cutting and my imagination on the dimensions.
The stanchions are made from ¼” plate. The rest is .062 sheet. I bolted the end plates to wooden end caps with nut inserts. The aluminum welding was done by Robinson Racing. They did my cage and these guys are always helpful no matter how small the job.
I chose to mount the stanchions a little more inboard than other designs. Looking at the trunk deck, I noticed that at the outboard position the deck was fairly flexible. Inboard about 8”, the deck is better supported by the structural piece bonded to the truck deck. This gives a 30” stance for the stanchions and makes for easy access for bolting. Also note that the trunk deck is not level. Your stanchions will need to be welded at about 2.5 degrees off 90 degrees to finish at 90 degrees.
https://photos.smugmug.com/Wing-M3/Wing/i-qCTG5fM/0/49320979/L/Mounting-L.jpg
https://photos.smugmug.com/Wing-M3/Wing/i-NMn6TxR/0/216eb443/L/Trunk%20mount%20-L.jpg
Now it was time to make the final mounting holes and positioning. I’ve given the wing about 10 degrees of adjustment and started off with “level” as a base point. Given the downward direction of the air coming over the roofline this should actually be a slight angle of attack.
https://photos.smugmug.com/Wing-M3/Wing/i-BrMDwXs/0/8c15e368/M/Wing%20and%20Dive%20planes%20007-M.jpg
I slotted the front mounting brackets so the wing will adjust from the front. The slots aren’t quite visible in this picture.
https://photos.smugmug.com/Wing-M3/Wing/i-mMXHx4S/0/84d0a48d/M/Wing%20and%20Dive%20planes%20006-M.jpg
Here you can see the rivets fastening the wing to the mounting brackets. I used 3/16” stainless steel rivets. They’re rated for 1,000 lbs shear and tension.
And finally some pictures of the finished product.
https://photos.smugmug.com/Wing-M3/W...es%20003-M.jpg
https://photos.smugmug.com/Wing-M3/Wing/i-XqB975B/0/a8edf7ae/M/Wing%20and%20Dive%20planes%20004-M.jpg
https://photos.smugmug.com/Wing-M3/Wing/i-vJfr5gG/0/3d78b674/XL/Wing%20and%20Dive%20planes%20005-XL.jpg
So, does the wing perform? I had the car out at CMP with the new aero and was very happy with the results. Though I don’t have a data acquisition device, I did shave about 2 seconds from my lap times at this track in May. The wing is creating enough low pressure under the wing that the end plates flex about an inch inboard at speed! The car was much more planted and most noticeable in sweepers like the turn 5 – 7 complex and hitting the kink on the back straight. I was able to hit the kink 5 mph faster at the same comfort level. I’m now looking forward to trying the wing out at Road Atlanta at Oktoberfest and playing around with the angle of attack. This wing took a lot of work to create, but has proven to be a very rewarding project.
https://photos.smugmug.com/Wing-M3/Wing/i-cchZvxn/0/8b8bd021/M/Wing%20and%20Dive%20planes%20009-M.jpg
Last edited by Michael9218; 11-10-2017 at 08:46 PM. Reason: FU Photobucket
Thank you!!!
Beautiful work!!!!
Holy crap, that is some quality work right there. Nice work!
Very awesome.
No PMs. Email through forum please.
Fantastic post!
Nice work.
jimmy p.
88 E30 M3 Zinnoberot - street
88 E30 M3 Lachsilber - SCCA SPU
87 E30 M3 Prodrive British Touring Car 2.0 Litre
04 Ford F350 - V10
06 Audi A3 Brilliant Red / 2.0 / DSG
Forgot to post the sources and cost.
Polystyrene large cell foam blank from Aircraft Spruce
http://www.aircraftspruce.com/catalog/cmpages/polystyrene.php
Hotwire cutter instructions
http://www.utahflyers.org/index.php?option=com_content&task=view&id=37&Itemi d=33
Hotwire .032 wire from Aircraft Spruce
http://www.aircraftspruce.com/catalog/cmpages/inconel600.php
24 volt 5 amp transformer
http://www.allelectronics.com/make-a-store/item/TX-245/24-V.C.T.-5-AMP-POWER-TRANSFORMER/-/1.html
Superfil surface preparation
http://www.aircraftspruce.com/catalog/cmpages/superfil.php
West Systems epoxy 105/206 slow cure
http://www.aircraftspruce.com/catalog/cmpages/westepoxy.php
West Systems epoxy pumps
http://www.aircraftspruce.com/catalog/cmpages/301PUMP.php
Epoxy squeegee
http://www.aircraftspruce.com/catalog/cmpages/comptoolrubbersqueegee.php
Unidirectional carbon fiber weave 4.7 oz
http://www.aircraftspruce.com/catalog/cmpages/unicarbongraphite.php
Plain weave carbon fiber 5.6 oz
http://www.aircraftspruce.com/catalog/cmpages/bigraphite.php
Aluminum sheet from Metal Express
http://www.metalexpress.net/cgi-bin/index.pl?&ac=acHome&mod=core&sid=3a85b797f9306c105 bd07b2adfa71ee6
Hardware from McMaster-Carr
http://www.mcmaster.com/#
Aluminum welding from Robinsons Racing
http://www.robinsonracing.net/
Very cool!
-Ryan
1993 325is racing car type thing....
Cool, Nice work.
Sponsors Needed, if interested contact me directly.
Most excellent thread!
Oh shite! That's amazing!
I entered this thread just expecting to see a "cool homemade project", but the end result looked incredible and closer to something professional! You are incredibly inspirational.
Like that
Looks very clean on the pictures.
E36 M3 S50B32 daily - E36 M3 S54 trackcar
They Say Money Talks, All Mine Ever Says Is Goodbye
Wow, op. This has to be the coolest thing I have seen on BFC.
How much does it effect how the car behaves?
Originally posted by pup "yeah. stick to pedophilia, racism, misogyny, homosexuality, the disabled and the poor"
Originally posted by Aindriu "It is made to be a crusing machine. Top down, cruise control on at Autobahn speeds, bit of classy music and an attractive woman in the passenger seat with the IQ of a peanut."
Great work. Can't wait to see it in person.
Mr. Trashy is gone... Mr. Ghost is here!
Nicely done, and very informative.
Best thread in a quite a while.
SOLD -A dozen ///M3s of all shapes
Very nice!
Steve E.
I have not had that much extra time this entire year, I am jeolous......nice work though
..."keep a little love in your heart and a taste of jazz in your soul."
VERY cool DIY project!!! I like the in-car wing oven, and just very well done all around.
Very nice write-up. Thanks very much for sharing.
Lee
Aftermarket Performance EXpress
Joe....I'm kinda surprised he beat you and Greg Smith to this one......
..."keep a little love in your heart and a taste of jazz in your soul."
yea, my days of building and racing are quite limited now by work and family. i barely keep the car maintained.
nonetheless, i am highly envious of his end product!!
Very nice. You are obviously an accomplished fabricator (and an engineer).
Chris
#175 CM E46 M3
Former Knee Dragger
Real name= Chris P. Lewis
Occupation= Green House Gas Creator, but I planted a GARDEN last year.
"When you live inside a vacuum, nothing sucks"
http://flickr.com/photos/8150451@N03...7602830737584/
Nice work!
I like the step of using the car as the oven.
Two questions. I stitch welded my uprights. I figured this was a good idea to relieve some of the stresses in the joint. My welding instructor suggested it to reduce warping but with 1/4 aluminum that wasn't my concern. Thoughts? Any concerns that it may crack due to vibrations?
2nd, size of the end plates. Those bad boys are huge. Thought about experimenting with end plate size? I'm going to guess it was the easiest part to fabricate (flat sheets).
Again nice work. I went the easy route and purchased the carbon element, quite envious of being able to make it yourself.
Cheers,
Carlos.
Super nice!! Great DIY!!!
Don
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