Test samples of some of the newest track materials have arrived and I'm
very impressed by the results so far. If there is demand, some of these materials may find there way into either commerically-made tracks, or as DIY materials. Currently, I'm working on refining the interior rail system and infield designs.
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Firstly, some of the rejected materials that we have tried and the rationale: The Regupol-like rubber has wonderful traction, but there is simply too much grip on the front and it feels somewhat unrealistic, not to mention the traction rolls if you use anything but near drift-spec tires (i.e. the Autoscale tires work very well, as previously mentioned and I'm sure a after-market tire maker could easily spec tires). On a practical level, although this material does lie very flat, it is much too difficult to work with. (Rubber expands making it rare to get a perfectly straight cut with layman's tools because it stretches as you cut). The weight is also prohibitive; almost a half-pound a square foot. Add the weight for infield materials and barriers and you are approaching 75lbs lbs for a small 8' x15' track. That's not portable unless you are in great shape. Clearly, this material is best for permanent installations, where it can designed into lanes built over plywood. Oh one more thing; it's kind'a ugly up close.
That said, this 'heavyweight' is perfect for the weighted infield areas and for "flattening" down portable sections of the material I will be using. So I'm glad I went through this extnesive testing excersise.
Regupol '6510', the material used on many European tracks seems to shred little pieces of itself, I have thus specified a slightly different (and less ugly) specification, but must note that the company manufacturing this stuff is not the easiest to deal with for a variety of logistical reasons.
My main reasons for testing rubber were: 1) the Europeans have built some nice tracks with it (all permanent though) and 2) it lies flat when deployed for roll-up practicality. Its weight (I hurt my back just lifting this stuff out of the truck) and difficulty to match edges (it comes in approx 48" wide so you have to piece the roll edges together to make your track wide enough) make it a no-go for any portable track.
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Ozite racing carpet: nice price per sq.ft., nice stuff to drive on with predicatble mid-friction traction ... provided you like cleaning the carpet fibers from your wheels every 5 minutes. I wish it worked for the d'nano, but it doesn't.
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Now for the good stuff ...
I can't disclose the exact formulation of the materials below, as some of them may end up in production, but I can discuss candidly what they offer, as I have tested the d'nano's out for more than 10 hours on each surface.
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One of the materials that satisfied all the requirements was thick, industrial felt; not the cheap acrylic stuff you find in craft stores, but rather a high-end felt with highly compressed wool % content. This is the only carpet-like material that would not shed too many fibers, (although still some) had predictable and consistant traction, and was thick enough to deploy flat. I may still build a track from it -- when I win a lottery ... at $22 per linear yard, it sure looks nice, but is just too expensive.
Without seeing the HTUSA tracks up close, I can't say for sure, but I suspect they are using a much thinner version of felt or man-made felt. Thinner=much cheaper, but also needing a permanent attachement, and thus no portability.
I did have the felt manufacturer spec out a much thinner version (like that used for pool tables), which makes for a very elegant infield material. I'll have more to say on that once it is finalized, as we are attaching the felt to another material to serve as the infield trim. The material is shown in the pictures in a variety of colors. The ability to deisgn your infield in a vareity of colors other than the traditional 'green' grass also is appealing. Once this material is refined and properly speced, it could also be offered to DIY track builders.
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Enough talk, cut-to-the-chase
The best material tested, by far, is a type of foam re-developed especially to spec by a Canadian company. It is lightweight (even less than EVA foam), comes in 6-foot widths, and is very easy to cut to any shape with a hobby knife. After struggling to get a straight cut with the rubber material, this stuff was a pleasure to work with. There are other unique advantages that make this the ideal track surface:
1) the material has a low-mid coefficient of friction, meaning that it you would spin or understeer too often without very grippy tires. So, I speced a ribbed texture, thus increasing the grip to a mid-friction coefficient, similar to the EVA foam tiles. It worked out quite well. Get the tires right (10-20 rears with wider 20 fronts) and it carves like a pro slalom skier, even at full throttle. Traction rolls are very rare, but can be induced if you push way too hard, just like a full-scale road course or oval ... lots of fun, easy to learn, hard to master -- and as racing should be ... your lap times improve as you find the right line around the track.
2) it
looks like a scale race track, in that the colour is a very dark gray. As I worked on it, vaccummed it, and my cats scratched it (unlike my kids they've been de-clawed) the surface became marked, looking like realistic skid marks.
The old Porta-Trax rail system, although expensive, adds another dimension of realism, while protecting the cars. You can see the outside rails that I made for the prototype track in the pictures.
3) The rib texture allows for some unique infield technologies, in that I can tape down stuff or Velcro and then remove it without ruining the surface. This is proving useful for repositioning infield barriers as I change the layout and for magnetically attached FIA cornering strips and barriers.
4) The material "heals" itself even better than EVA -- if I pin something to the track (as I did when designing realistic FIA warning edges), it stays put, and the pin marks 'heal' as soon as I remove the attachment -- this makes adding to the infield or changing the design of the track very easy.)
5) The material comes in 6' widths (just within the shipping acceptance length for many carriers) and can be cut to any length. If you want a track wider than 6', you can easily adjoin another piece by taping underneath. I will be experimenting with 8 and 10 foot widths after I get the first prototype built.
In addition to the d'nano, Mini-Z's run well on the material, there are no fibers to contend with, and it rolls-up for easy storage.
The only 'negative' characteristic needing to be tamed is its tendency not to lay completely flat (there are very small natural ripples, that some may prefer as being scale-like), or, you can use the infield material to reduce rippling to almost negligible. The curled-up edges you get from constantly re-rolling disappear when the rails are added.
The test track I am building is 14' x 6'-1'' -- a very compact size. At first, I wanted to try something eloborate, with multi-levels and a much larger size; but this size is much more practical for most and still large enough for three challenging layouts: triple chicane, banked oval and perhaps a 'suicide' figure 8. I also want to see how this size will overlay on a pool or ping-pong table.
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This has been a lot of work and very educational -- but it's important to build a great track if you want to experience the full potential the d'nano has to offer. I would certainly appreciate any feedback on the materials, positive or critical, and whether or not you think there is a market for this as a DIY track material and/or a finished product.
I should have a fully completed track to show in about 2 weeks ...I've even ordered some carbon fiber trim for the exterior rails, as my four teens seem infactuated with that material for some reason and are already looking for places to stick it on my full scale Durango ...there are some things that I'm just getting too old to understand. - Lorne
Some of the various surfaces and infield materials that I've tested. The rubber is on the right, standing up 48", the rolled foam on the left at 72". Infield felts are shown layed out. In the left corner you can see the old Porta-Trax rail system attached to the new surface.
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a close-up of the unique surface texture.
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mock-up of what a DIY or pre-fab track might look like. "Look Ma, no track seams, no pins". Sharp eyes, will notice that the fake spectators are 1/32 scale and not 1/43. The lane is also much narrower than is practical.