Here is what I wrote on Facebook but as it was a reply the words were buried.
some thoughts regarding rules...please add or suggest improvements or add where I have forgotten something.
Minimum Ground clearance….1/8" or 3.2mm Max track 45mm Max wheelbase…? Is there one? Black coloured guide flag only. Black Urethane tires only Max tire width 5.0mm contact patch Minimum wheel diameter class 1…?…..class 2…?… Motors….class 1, 14k rpm class 2, 23k rpm Chassis made from brass, wire, plastic, nylon, wood, steel, PCB board Bearings can be ball race or oilites Bodies made from resin, plastic, wood but no vac form Cars from Pre WW2 era only Driver/s must show as full a figure as possible No streamliners
In complete agreement with one suggestion and an observation:
Add steel to the allowed chassis materials
Tire sizes: Some of the 30's voiturette cars mounted wheels as small as 16" - a 16" wheel will be about 18" to the outside of the rim, or, in 1/32 scale 14.3 mm. The larger cars rarely carried anything smaller than an 18", 20" at the rim or, similarly about 16 mm. These were cotton cord tires and the race-to-race variation is size reflected the need to keep rotational speed below the point at which the carcass would simply explode. (The centripetal force is proportional to the radius multiplied by the square of the rate of rotation thus fast circuit = big wheels
Post by Peter Seager-Thomas on Sept 18, 2018 10:11:31 GMT -5
Perhaps the 'No Streamliners' rule could be modified to 'No all enveloping Streamliner bodies'. Now, it's unlikely that anyone would enter a P3 with the fairings behind the wheel (Marlon made one). Since the rule is undoubtedly to stop full width chassis' why not have a maximum chassis width?
I would recommend a tire width of a maximum 5mm. It's period for the Prewar era, also within the realm of widths for "voiturette" cars of the post war time.
Furthermore 3/32" is too slammed for the period. Heck, if you look at the Can Am cars in an actual race of some 20 years later, 3/32 would be too slammed for that time period too.
You are quite correct but here is the problem: Unlike the typical prototype motor with the crank output near the bottom, our motors are symmetrical so half of the motor (and any associated chassis parts) are below the rear wheel center. As an example, I have recently built up 2 C type Jags. With the bottom of the body correctly aligned in relation to the wheel centers,there is a good bit of chassis needing flat black "invisibility" coating. Perhaps an alternate solution would be to develop a set of wheel/tire specs, take a typical radius, subtract half the height of an FC/FK can and the allow a bit for chassis, rattle pan etc.
I had someone who questioned the black colour for the guide rule. This is for appearances sake. I know there are some great red guides but with little body work or chassis to cover them they would stand out too much in my opinion.
Post by David Mitcham on Sept 20, 2018 7:07:23 GMT -5
A small contribution from me.
First, the PCS 19" wire wheels have tyres 5mm wide tyres - at least they do on my alfa 308.
Second, regarding motors I think 14k rpm is too low and I'm not sure there is much, if anything, available at that level - on the Pendle website there is only one MRRC motor that revs below that at 13k. The DArt website doesn't seem to be offering BWA motors anymore but I may have missed something. Slot Car Corner offers the M/T 14.7k motor (although test indicate it revs somewhat below the formal rating). Personally I would go for a rev limit of 18k FF050 motors for the Voiturettes - partly based on availability from suppliers. I would say 16k rpm but the SRP 16k rpm motor doesn't seem to be available any more and from some research carried out by the Tasman organisers there is little difference in performance between the 18k and 16k motors (I'm sure Phil or Alan would provide details). For the GP cars, 25k - FF050 or Ff030.
I think that simply using the same motor size spec and differentiating based on revs would offer insufficient distinction between the classes.
The FF050 motors can be quick - I have a 4CLT fitted with a "black can" (30K rpm?) FF 050 motor and short ~ 4:1 gearing and it runs very well but I think it would be interesting to replicate the 30's approach - voiturettes were typically displacement limited while the GP cars were all over the place - 750kg, 5.6 litres etc.
So - alternative suggestion: restrict the voiturette class to FF 050 or 030 motors and for the GP class - 25K RPM but any motor (this would, for example, allow the Slot It "Flat 6" 22.5K motors - an interesting choice for some of the GP cars)
This would promote a wide range of approaches and probably an equally wide range of results but this is how one learns. (I currently have a very firm grip on next-to-last in the IPS with what I thought would be an interesting departure in design)