NoCom Tailbox project
NoCom Tailbox Project
What could we possibly do to make the NoCom speed Missile faster? After much discussion, the Chicago four area NoCom riders (Zippy, Sean, Larry and Warren) decided that it would be faster with a Razz Fazz style fairing. Because none of us wanted to take on the project individually, this will be a group WISIL project.

Rick W. volunteered to perform the CAD work to allow templates to be easily printed. The first step of this was to take measurements of the NoCom, and decide general fairing shape. 

January 2008
Warren took pictures of the NoCom and made measurements.
Zippy, who was very familiar with the Razz Fazz fairing, added the general fairing shape in red. 
Sean is researching NACA wing shapes and other aerodynamics issues.


Here are some pictures of the actual NoCom tailbox.

Thomas Schott on his Razz Fazz at the IHPVA championships in 2002.

Dennis Ahrens riding Thomas' Razz Fazz at the IHPVA championships in 2002.
Chris Evans on the VK3 with Razz Fazz TB
Rick Wianecki's first scaled CAD draft of the NoCom RF style TB.
Zippy suggests changing rear profile
Warren shows Ricks TB on NC Side
Warren shows Ricks TB on NC Top
Warren resizes the RF TB for the NC.
Zippy refines the outline (in white).
Rick refines his CAD drawings (new side view in yellow)
Rick generates final templates. This version of the templates is designed to be constructed of 1/2" insulation foam, then skinned with strips of 1/2" foam.
Rick generated the templates in 2" slices. This will allow us to cut out sections of 2" foam based on full scale drawings, and stack them together.

The stack of foam will be sanded smooth, covered in fiberglass, and then smoothed further to make a male plug.

Rick generated the CAD drawing DXF files with the individual layers templates on it, and Warren had the drawings printed onto four 36"x96" sheets of paper by Kinkos. The tailbox will require 3 sheets of 2" - 4x8 ft foam to construct the plug.
Zippy made a rendering of what the tailbox would look like when using red texalium as the outer layer.
Warren and Sean spent a Saturday building the initial foam core of the fairing. 3 - 4x8 foot sheets of 2" foam were acquired, and the drawing were taped down to them.

Here, Sean uses a pounce wheel to transfer the pattern to the foam.

Sean has a happy #11 smile after rough cutting all 34 sections of the fairing.

That makes it 68 inches long, or 5 feet 8 inches.

Warren stacks the sections onto wooden dowels to check the alignment.
Sean applies the dabs of 5 minute epoxy to glue the sections together. A pile of glued sections sits to the left weighted down with some paint cans.
Sean stands next to the stack of foam to show the scale of the fairing.
Modern art.

Now comes the sanding and shaping.

Sean Costin relates the following:

"I took down the edges on the Tailcone today."


Photo by Sean Costin

Photo by Sean Costin
"To get it ready I used a jigsaw and cut a 3/4" slot in the bottom to accommodate a board I would use to mount the tailcone in my Workmate. I used a 2 part foam to bond it in place. This worked quite well."
"I used a 12" rasp to do 90% of the work and used a sanding spline to top it off."

Photo by Sean Costin

Photo by Sean Costin
"I think there are either some problems with the plotting or the Cad templates because there are some bulges in areas where they really should not be."
"My brother related some problems he had with plotters. He measured up some things that were supposed to be 100% and found that they did not match the dimensions."
Photo by Sean Costin

Photo by Sean Costin
"The photos illustrate an area about 6" from the end of the tail toward the top where it should be narrower and a sharper dip below and forward. These problem areas are symmetrical to each side, so I am confident that it came from the plot."
Sean and Warren found time to work on the tailcone.

To figure out how to shape the leading edge of the tailcone, we sat on the NoCom and drew outlines around our bodies. We then cut out a template which we attached to the leading edge of the tailcone to visualize how to shape it.

 Because our shoulders are actually 4" or so forward of the NoCom seat back, we needed to scoop out the center of the back area to ensure a good fit between our shoulders and the tailcone.
 Sean sits on the tailcone to show the shoulder to leading edge area.
 Side view, Sean demonstrates the world record position. We have begun to cut off the areas that are obviously not needed.
 Front view. Looks good!
 After more filing, Sean does a second test fit.
 Looks better.
Warren - top view.  
 Side view showing head a neck area. We'll need to cut more out for head and helmet clearance.
Grr, where's he at? Lemmee at him...

Oh. Warren demonstrates the riding position on his NoCom.

The shape is looking better.
Sean's elbows are up higher than Warren's. We definitely need more helmet clearance 
Shaping is done for the day.  
Here you can see where we added expandable foam to the fairing sides to fill in the low areas. 
 Front view with Sean's NoCom.
 Fairing bottom from front.

Sean worked to refine the shape in 2008. The plug made it's way to Warren's barn in the spring of 2009, and Warren worked to get it ready to cover with a layer of fiberglass. Finally it is ready.

I covered one side of the tailbox in fiberglass today. Next weekend I'll do the other side. After that is done I think I will cover it in plastic wrap and make a mule TF so we can see if it really fits the NoCom before I do the bondo work to make it pretty.

It's all covered in fiberglass. Now I find all the imperfections and fill them with aeropoxy, a lightweight epoxy based body filler. And sand, and sand, and sand.....

After a bunch of filling and sanding, the plug was handed off to Zippy for finishing.
Today is day 1 of putty play time with a gigantic tailfairing for my Tinkerville Special. Yee haa!!!

Warren and Sean did all the work so far and now I get to cobble and tinker it for a smooth surface to go super fast in 2010.

Here are the latest photos of the Ultra Blimp. So far about 40 hours of adding thin multiple layers of Aero Epoxy followed by spline sanding high spots. Both sides required a lot of fill for a smooth bow shape to the tail end. The texture looks awful under fluorescent light but in daylight the plug is starting to take good form.

Probably another 40-80 hours or so to smooth sand some of the left side and the bottom quarter. The bottom has to be rough sanded, filled and smooth sanded before priming the plug. I plan to cut off the bottom board and drill holes for rods attached to a base for primer spraying.
After thinking about some forum posts for a couple days I decided to change the entire front shape of the TF to a rounded bubble shape. Each rider can cut the opening to follow the contour of their torso similar to a Birk Comet.
LZ visited today to check the fit from front, back, sides and top. There were too many hard and open edges between the rider and the fairings front edge. The top protion also pushed the head and neck too far forward and had to be altered. The photo comparison shows how I want to smooth the transitions from faring edge into the torso, shoulders and head.

I'm basically adding several inches of foam to the top of the plug. When molds are made and a TF is produced the opening can be cut to fit each individual riders shape.

I already set up a border and poured expandable foam on the front surface. When it hardens tomorrow I will remove a lot of the material and shape it down to size needed for a rounded front edge. I am not making the faring wider.
This is after 4 hours of carving. Next I will drape a layer of fiberglass on top of the foam, let it cure then smooth shape it with Aero Epoxy and sanding splines. This TF can now be produced from a 2 piece mold instead of 3 pieces with a concave front face.
Big difference from the 9/08 photo in this thread. This new front shape will allow a smooth transition from rider to fairing.
The front of the fairing will be similar to the opening of a RazzFazz. The opening will have a rounded edge the rider fits into.
Zippy did a light check following the shadow line of the TF.

The right side is looking good for this stage of of pre priming. Just a few small air pockets to fill and smooth out.

The upper left corner had a big dip and required a bunch more gooey filler to be slapped on. He thought he was all done with shaping and now he gets to do it again.. 
Zippy says:
"After cutting off the base board that was bonded inside the foam core I was able to refine the bottom surface of the plug. Both left and right sides now have similar shape and curves from front to the tail with a narrow flat bottom edge for the rear wheel. Thick multiple layers of Aeropoxy Light were added and shaped with flat hand rasp tools to get the smooth curves and flow needed."
"Next, a very thin top coat of Aeropoxy was added using a popsicle stick to fill in the small grooves from the rasp files."

"When the surface cured I pre drilled a strip of plywood with .5" holes for dowel rods. I placed the drilled board on the bottom of the plug to drill and tap holes in the plug needed to set it on a base for light surface sanding with splines."

"The next step after the surface is clean will be making a test fit fairing to decide if any additional changes are required for rider and bike fit prior to priming and waxing the plug." 

Zippy took the plug to a body shop for the final sanding and primering.

He says:
"I picked up the plug from the body shop this morning and the guy did a real nice job smoothing out the surface."
"Next steps in the process are waxing, making a comp fairing then the 2 piece mold if the comp looks good. " 

The finished plug now makes it's way back to Warren's house so the female mold can be built. Garrie Hill documented the process to make the female mold.

The first step was to build a form that the plug will mount into, to allow flanges to be molded into the female mold.

I transfered the plug's side view to a sheet of 3/4" MDF. I used the L shaped piece of MDF in the picture, with a marker pen taped to it. The fairing is supported with some chunks of modeling clay.

After cutting the hole out, the fairing did not quite fit, so I had to trim a bit more here and there before it would fit properly in the hole.

I also added some legs and supports to the mold flange form.

Here's the form with the hole cut into it.

I marked the centerline on the plug with a magic marker, then I mounted the tailbox plug in the form.

I then filled the gap between the form and the plug with modeling clay.

After applying several coats of wax and then mold release a couple weeks ago, the mold was ready to cover. Warm weather finally allowed me to start that process. Here's the plug covered with 3 layers of fiberglass.

Next is adding some strips of foam and another couple layers of fiberglass.

The right half female mold is done. I removed the plug from the MDF form and trimmed off the excess fiberglass cloth. The clay, wax, and mold release made it easy to pry off of the form. Time to start waxing the left side.

Glassed the left side, and after the resin had hardened (just a few hours in my hot garage), pried the right side off the plug and washed off the mold release. Looks good and seems very smooth. There are a couple bubbles I will need to fill, but otherwise I'm happy with how it turned out.

Tried to get the other side off but decided to wait until it had cured 24 hours before trying again.

Meanwhile 3 months later, the vacuum pumping is chugging away in the garage to complete the first half of our first NoCom tailbox.

Several weeks ago I laid up the first layer of old yeller kevlar. I wanted to do a single layer to see how stiff it was. I wasn't able to get a good vacuum, and it was really hot out and it was my first time I ever vacuum bagged anything, so it was not a lot of fun.

Fortunately it wasn't a loss. The single layer was too floppy, so I decided it need another layer. After sanding the ridges of epoxy off the inside of the kevlar layer, I laid up the inside layer, fiberglass this time, with a single foam rib about where the rear dropouts are located. Tonight's layup is enjoying a 20 inch vacuum! If all goes well I'll be able to do the second half layup tomorrow night.

The second fairing will be made with AA's red kevlar. It should be spiffy.


I didn't get a good vacuum on the second half, but it turned out ok.

I took one of the tailbox halves to a time trial that Sean, Zippy and I were racing in, and fit it onto Sean's NoCom with a roll of duct tape to prop up the tail.

I'll start attaching the two halves together this week and start thinking about mounting it.

The tailbox is now put together, and looks pretty good. I cut holes in it and tested the fit.

It still needs to be mounted to the bike.

I'm leaning toward making a molded piece that will fit over the shoulders of the seat to attach the fram in that area. The frame will also bolt to the side edges of the seat in the butt area. The thrird connection point will be for alignment, and will consist of an alignment bracket from the fairing bottom to the splitter plate by the back wheel. The combination of these 3 brackets should keep the fairing in place.

The entire back of the bike is swallowed by the tailbox.

Because I have too many projects, and this fairing is "good enough", I will hand off the molds to Zippy for him to build a fairing for himself.

After cutting the shoulder areas out to fit me, I made some clips that fit over the top of the seat, and used some foam and fiberglass to attach it to the fairing.

Zippy had some problems getting the fairings to release from the mold. We decided it was not a good idea to put the vacuum bagged tailbox halves in the mold out onto his hot asphalt driveway in the sun to cure. It would get very hot and melt the mold release wax, which made it very hard to remove. Because of this Zippy ended up reinforcing the molds and removing the ribs. He also did a lot of work to fill in the bubbles. After more issues we decided that the inside of the female mold should be coated with tooling gel coat to make it super smooth and non-porous so the fairings release easier.

To that effect, Zippy sanded off the primer he had sprayed on the inside of the fairing, and then handed off the fairing halves to Sean to have him spray the tooling gel.

Here's an update from Sean on on the tooling gel coat.
I bought a large orifice cup style sprayer and put in some un catalyzed gel to see how it shoots. The gel is the consistency of pudding and air suction bored a hole through the material. a decent amount of material came out but the finish was pebbly. I also did a test with a foam brush and a bristle brush to see if the material leveled out nicely. (It didn't)

I contacted US composites the manufacturer to find out what solvents can be used to thin the gel. They said styrene can be used.

#70 Styrene Monomer is the recommended and accepted thinner for polyester resins and gel coats. Most gel coats can be thinned 2-5% to make them suitable for heavy spray equipment or other special purposes. Then the guy asked if I was using a wax additive. Otherwise the Gel coat will remain
tacky. Obviously not to good for sanding smooth.

Get a Complete Cure
# 71 Styrene Wax is a 5% solution of paraffin dissolved in styrene that may be added to non waxed polyester resins and gel coats to prevent the prolonged tackiness associated with thin sections of polyesters. If the resin contains paraffin's, the wax will rise to the surface and protect the curing resin from the inhibiting action of the air. However, if the resin is allowed to fully cure, the paraffin's on the surface will prevent adhesion of further coats of resin and must be sanded off prior to additional
applications. We recommend adding #71 at 5% for thin coatings. Use with #1040 Hi-Gloss Additive when performing repairs below the water line.

Then he tells me about Duratec. Which is apparently a lovely 1:1 product which will give us a full hard sandable cure and help with material flow. I think I will skip the styrene altogether and just buy a gallon of Duratec which will reduce the viscosity.

Duratec Clear Hi-Gloss Gel Coat Additive
Mixed with gel coat to reduce viscosity, porosity and permit a complete open air cure.
1) Low Porosity - when used for repairs, blending the additive with gel coat produces a low porosity surface.
2) Reduce Orange Peel - the low viscosity of the blend results in a smooth finish that is easily sanded.
3) Improved Properties - for mold surfaces, the blending of the additive with tooling gel coat creates a higher heat distortion temperature, improved gloss retention, increased impact resistance, and reduced subsurface porosity.
4) Superior Finish - when blended one-to-one with gel coats, the additive creates an air cure, enamel-like coating. No air-dry additive is required. When used for gel coat repair, surfaces are restored to like-new condition.

The fairing halves are ready to make some tailboxes, but nobody has done that yet. Except me. I finally got the tailbox I built last summer mounted on the NoCom, and raced it at this year's Northbrook velodrome races.

Picture by Jeff Hunn

It looks pretty good and I think it adds a MPH or so but it was hard to tell. It was really hot and the tailbox blocked some of the cooling. My sprint with the tailbox was definitely faster.

Picture by Jeff Hunn

Epilogue: After a season racing with the tailbox, and comparing speeds to my previous years results for the same races, it was determined that the tailbox did not make enough of a difference to warrant using it. The size of the tailbox made the bike difficult to transport, and it cut down on rider cooling. Based on this testing it was determined that as the seat recline increases, the aerodynamic gains of a tailbox (even a large one!) decreases. For a bike like the NoCom with a seat around 15% degrees, a tailbox provides negligible benefits between 20 and 30 MPH. At speeds above 30MPH on the Nocom the tailbox does provide a significant speed boost, but my race speed is closer to 27 MPH.

To  date, nobody else has seen fit to make a fairing from the molds that we created.

Moral of the story: Don't bother making a fancy mold for your fairing in hopes that you will make more than one.


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