Designing the Air Intake for Milan

I went for a ride with the Milan while in New Hampshire this past weekend. Earlier morning start and cooler weather for the ride, so I rode with the manhole cover on, and had a long climb up Kancamagus Highway. I rode shirtless, and could feel appreciable air flow past my body, so I believe the air holes I added at the rear have been helpful. Now, on to work for the air intake on the front!

Obviously I want the finished part to match the body contours exactly, or nearly so. I keep trying different approaches to find the best way to do that!

I taped some paper onto the lower section of the nose, and then added strips of release or flash tape onto the front of the Milan. Composites don’t stick to this tape. Then I added 2 layers of carbon fiber, and I used some flash tape to hold peel-ply against the carbon fiber. (The peel-ply is fabric that gives a smoother finished “backside” on your CF piece, and doesn’t stick to the finished product; it also works with breather/bleeder cloth to allow excess resin to be sucked up, so your piece has the proper ratio of fabric to resin). I left it to cure overnight and, before I removed it I marked off the vertical center-line of the Milan as well as the headlight position, then took the piece off. My design is going to place the SPAI below the headlights, since that is the stagnation point, and by not placing it around the headlights it will make closing off the SPAI easier in colder weather (I’m also going to make a cover piece that will match).

OLYMPUS DIGITAL CAMERA

I removed the CF (carbon fiber) piece, and trimmed the outer edges off. With a paper cut out of the SPAI that I designed, I used a paint marker to indicate where I wanted the opening. Because I made this piece in a low-tech fashion, the surface was a bit uneven and bumpy, so I used a table top belt sander to smooth the larger contours down. I cut out my air opening design, then cut out a 12″x 12″ piece of MDF plywood, glued on about 5″ of foam, and shaped and contoured the foam to be a support under the CF piece. Then used hot melt glue to bond this CF into place.

In the background of the photo below, you can see the saw I use to cut off large chunks of the foam (Lowe’s). The other shaping tools are from Perma-Grit, extruded aluminum shapes in different lengths and contours, they have a rough titanium oxide sanding medium on one side and smooth sanding medium on the other. Sorta expensive but well worth it. (FYI I buy most of my material from FibreGlast). I’m using 2 pound polyisocyanurate sheet foam, mix of 1 and 2″ thick.

CF piece made on the nose of the Milan, and foam to support.

Then I cut and dug out the foam to shape the air intake “hole” itself. I had been using a Dremel hand held rotary tool in the past, but CF dust is very nasty to the motor and brushes, and of course the tool is right down there in the cloud of CF dust, so a couple months back I purchased a Foredom rotary tool, with hanging motor and foot pedal speed control. Wow! what a great difference; highly recommended, puts the motor further away from the dust, you can reverse direction which helps make the bits more effective, and they have some great bits that have saved my fingers from a lot of laborious sanding. And the work piece goes into a small drill chuck; I always dreaded changing bits on the Dremel, with little plastic shaft lock that barely holds, and then changing collet size first…. And the Foredom is made here in my home state of Connecticut! They even offer a small belt sander attachment, which really works very well (yeah, I’m a tool guy, had to get one 😉 ).

Once I was satisfied with the design I applied some auto body filler; rough sand and then fill in low spots, and then apply more auto body filler. The outer surfaces are easy enough to sand with the Perma-Grit sanding blocks I use, but the Foredom and polishing/grinding bits make the interior surface work a lot easier.

Foredom hand held tool, and they have various bits that are great for mold making.
My improved lighting set up!
Small belt sander attachment

I just put on second coat of gray gel coat, so I will sand that later today. And in the new theme of being smarter (yeah, I’m still learning 🙂 ), I will make a quick test piece off the flatter outer surface of this plug, just to be sure I’ve matched the contours of the Milan well. If that comes out correct, on to making the mold! And if I’m not happy with it, this is where changing things would be the least effort.

2 coats of gray gel coat

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