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Post by munter on Sept 20, 2018 13:33:02 GMT -5
The BWA 14.5k rpm motors are still available from the original source....BWA(just bought a few) but perhaps the SRP 18k motor is the one to set the limits on for the Voiturette class. The GP class could be set at open rpm but it would be a brave person who puts a flat six in a narrow thrities car and expect to do well in a proxy....unless measures were taken.
Keep talking chaps
PS thanks for the PP rim/tire specs, David.
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Post by EM on Sept 20, 2018 15:03:46 GMT -5
One of the games I enjoy playing is "data mining" - many proxy reports include information on car weight, wheelbase and track dimensions, tire diameter and width etc. I will take this data and plot it against finishing position to see if I can discern any trends that would inform future projects. Very broadly I have observed the following:
Tread - wider is better (hardly a surprise)
Weight - lighter is better - an "OK" correlation but there are often one or two outliers
Tire width - no apparent trend
Wheelbase - no correlation but I suspect that this is because, for most classes, WB variations are small
Torque - interesting...no correlation with published motor torque but if one calculates an "effective torque" i.e. (motor torque X gear ratio)/tire diameter the results suggest lower = better - perhaps a question of control-ability.
Based on the latter, I'm tempted to try a "flat 6" with tall gearing - 2.2 : 1 for example, on a big wheeled car like a Merc or AU.
EM
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Post by munter on Sept 21, 2018 2:40:25 GMT -5
Al, I am not tempted to do that...I would want the flat 6 geared lower (numerically) so it revs more and brakes the car more effectively.
On another point, I measured some rims today and have altered the wording to the wheel/tire width rule...ie contact patch 5mm.
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Post by maxrossmassler on Sept 21, 2018 12:03:39 GMT -5
I think 5mm contact patch is an improvement. The large diameter wheels/tires will help with the overall drive ratio, but I don't think they will help with motor braking. Interesting subject.
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Post by chrisguyw on Sept 21, 2018 12:52:57 GMT -5
I think 5mm contact patch is an improvement. The large diameter wheels/tires will help with the overall drive ratio, but I don't think they will help with motor braking. Interesting subject. The 5mm contact seems very appropriate for this era of cars., as does the increased ground clearance....both good decisions. The od dimension of the rear tyres will absolutely affect the final drive, with acceleration, top speed and braking being affected. Simply make adjustments with pinion and Crown tooth count. As far as using a Flat 6......to each his own, but personally, given the ground clearance, track width, and resulting cg., I would run and hide from that option. Cheers Chris Walker PS I hope to find the time to build/submit an entry.
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Post by Andrew Rowland on Sept 21, 2018 13:30:45 GMT -5
John, my suggestions as follows: (Taken from the CSCRA website for your consideration).
CAR STANDARDS 1. SCALE & DIMENSIONS All cars to be accurate 1/32 scale representations of a full size car. As most racers are very much reliant on manufactured bodies, which are not always perfect, there is no specific requirement for exact scale length and width for body shells. They are, however, expected to be reasonably to scale. If you push the boundaries too far you may be asked to run something else. Wheelbase and Track measurements must be 1/32 scale within + or – 2mm. “Wheelbase” is the distance between the centre lines of the front and rear wheels. “Track” is the distance between the centre lines of the left and right hand wheels at the front and at the rear of the car. No car should exceed the maximum width permitted for each class. Cars will be measured over the outside width of the tyres. When the car, in race ready condition, is placed on a flat and level section of track to be used for the event all tyres must touch the track surface and roll when the car is pushed forwards. It is the entrant’s responsibility to prove the accuracy of any car. If there is any doubt the scrutineer may ask you to run something else. The scrutineer’s decision is final. 2. BODIES All body shells must be of hard plastic, glass fibre, resin, wood, metal or similar material. Vacuum formed bodies are not permitted. All cars must be finished in a style sympathetic to the period being represented and carry at least two racing numbers. All cars must have clear windscreens etc fitted where they appear on the prototype. Vacuum formed windscreens etc are permitted. All cars must have a suitably decorated and period correct, 3 dimensional, representation of a driver consisting of at least a head, shoulders, arms, hands and the upper part of a steering wheel. Vacuum formed interiors and drivers are permitted but must be realistic. The chassis, motor and all running gear must not be visible from above or through the cockpit opening and engine bay unless that which can be seen represents parts of the real car. Suspension components and exhaust systems for example and, on the later period cars, the rear floor and diffuser. The slot guide must not protrude beyond the front-most point of the car when in the straight ahead position. 3. WHEELS & TYRES Tyre width limits in all classes are overall. All wheels must be representative of real wheels or have suitable inserts fitted. Silicone tyres and sponge/foam rubber tyres are not permitted. All tyres must be dry and free from additives whenever the car is placed on the track. 4. MOTORS & CHASSIS Motor choice is free. Chassis design and construction is free but must comply with sections 1 to 4 and any individual class restrictions. Any chassis design which allows the wheelbase or effective track dimension to vary will be measured at both extremes of movement and must remain within the + or - 2mm scale tolerance and not exceed the maximum width restriction for the class. On cars fitted with steering the wheelbase, track and overall width will be measured with the steering in the straight ahead position. Minimum ground clearance will apply under the motor and the entire length of the chassis and body, unless stated otherwise. This will be measured with the car sitting on its tyres on a flat and level section of the track to be used for the event or on a flat test block which matches that track. Drive gears, and side skirts on ground effect cars, may be below the minimum ground clearance but must remain clear of the track surface at all times. One slot guide only is permitted. Blade designs must be no more than 25mm long and pin designs with more than one pin must have the pins within an overall length of 25mm. Traction magnets are not permitted.
Event organizers should feel free to select specific year ranges or types of car from within each class or to combine periods and classes as they see fit. NOTES: 1. In all classes except GP1 tyres must be visible from above the car unless the event organizer specifies that ‘streamliners’ are eligible. 2. In classes GP1 to GP5 any car which has side tanks/fairings between the wheels must have these mounted as part of the body and must not have any part of the chassis, or any ballast, under or in these tanks/fairings. GP1a - Pre-1934 Over 2 litre Open Top Cars • Motor orientation: Inline only • Front wheels and tyres: Minimum diameter 24mm, minimum width 4mm • Rear wheels and tyres: Minimum diameter 25mm, maximum width 6mm • Minimum ground clearance: 3mm • Maximum overall width must not exceed Scale track dimension +6mm. GP1b - Pre-1934 Under 2 litre Open Top Cars • Motor orientation: Inline only • Front wheels and tyres: Minimum diameter 22mm, minimum width 4mm • Rear wheels and tyres: Minimum diameter 23mm, maximum width 6mm • Minimum ground clearance: 3mm • Maximum overall width must not exceed Scale track dimension +6mm. GP2a - 1934-1951 Grand Prix and Indy Cars • Motor orientation: Inline only • Front wheels and tyres: Minimum diameter 21.5mm, minimum width 5mm • Rear wheels and tyres: Minimum diameter 24mm, maximum width 7mm • Minimum ground clearance: 2mm • Track dimensions must be 1/32 scale within + or – 2mm but must not exceed a maximum overall width of 53mm GP2b - 1934-1951 Voiturettes (1.5 litre supercharged and 4.5 litre normally aspirated cars) • Motor orientation: Inline only • Front wheels and tyres: Minimum diameter 19mm, minimum width 5mm • Rear wheels and tyres: Minimum diameter 21.5mm, maximum width 7mm • Minimum ground clearance: 2mm • Track dimensions must be 1/32 scale within + or – 2mm but must not exceed a maximum overall width of 50mm
As the rules state the year range can be limited as desired and as you have specifed pre war the range can then be limited to 1939 rather than 1951.
Kind regards Andi
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Post by EM on Sept 21, 2018 13:35:35 GMT -5
"Flat 6" motor?
It all depends on the final rules of course but, should the rules permit, my naturally contrarian nature would likely push me towards giving it a try. I have a partially finished Alfa 2900B with typical 30's dimensions and tire sizes that might be pressed into service as a trial mule.
The torque of an electric motor is generally a function of # of turns of wire, wire size and magnetic field strength and I would guess that the braking effect would reflect the same but that is based mostly on blissful ignorance.
EM
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Post by munter on Sept 21, 2018 13:49:11 GMT -5
Thanks, Andi, that helps...give me some time to mull those over, please.
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Post by munter on Sept 22, 2018 0:34:50 GMT -5
OK I have given three rule sets the once over and have rehashed what I think is OK. There are a couple of gaps so please look for them and make suggestions, in fact continue to make suggestions about anything you think is important.
Body Must be 1/32 scale + or – 1mm Hard body of a prototypical car, body must be solidly fitted to the chassis in such a way as to truly represent car, it cannot appear to be lowered to chassis. Body float or rock is acceptable. All body shells must be of hard plastic, glass fibre, resin, wood, metal or similar material
Fixings should not be visible above or to the sides of the body.
All body fixings must be securely fixed to prevent loosening/dropping off during racing.
Streamliners or vacuum formed bodies are not permitted.
All cars must be finished in a style sympathetic to the period being represented and carry at least two racing numbers.
All cars must have clear windscreens etc. fitted where they appear on the prototype.
Vacuum formed windscreens etc. are permitted.
All cars must have a suitably decorated and period correct, 3 dimensional, representation of a driver consisting of at least a head, shoulders, arms, hands and the upper part of a steering wheel.
The chassis, motor and all running gear must not be visible from above or through the cockpit opening and engine bay unless that which can be seen represents parts of the real car. Suspension components and exhaust systems for example.
Chassis Any material list here can be used to construct a chassis…brass, wire, plastic, nylon, wood, steel, PCB board
Wheelbase and Track Both dimensions must be set at 1:32nd scale plus or minus 1mm. Max width GP cars 53mm, Voiturette 50mm, measured bulge to tyre bulge across the width of the car.
Bearings can be brass, oilite or ballrace Ground Clearance From the bottom of the chassis including ballast to track surface at any point. Including Screw Heads. Grand Prix Car 4mm Minimum Voiturettte Car 3mm Minimum
Guide Choice The slot guide must not protrude beyond the front-most point of the car when in the straight ahead position and viewed from above. Black in colour only. One guide per car.
Motor
Motor Alignment - In-Line only
Front Wheels - Any wheel and tyre combination but must give a true representation of the original (I.e. no low profile or inappropriately narrow tyres), appropriate period style 3D inserts must be fitted.
Front Tyres - Overall diameter of wheels and tyre must be: GP cars Min Diameter 21.5mm with a max width of 7mm. Voiturettes Min Diameter 19mm with a max width of 5mm. Contact patch 5mm
Coated Front Tyres yes but only to reduce grip.
Rear Tyres - Overall diameter of wheels and tyre must be: GP cars min Diameter 24mm with a max width of 7mm. Voiturettes min Diameter 21.5mm with a max width of 7mm. Tyres are measured bulge to bulge not contact patch Contact patch 5mm
Glue & True - yes
Axles - Free Choice
Gears - Free Choice
Magnet No
Ballast - Free Choice
Weight - Min
Livery - It is essential that the car runs in an authentic livery from the period
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Post by EM on Sept 22, 2018 9:23:40 GMT -5
Reflecting the current sorry state of my hands: 10 thumbs up!
EM
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Post by maxrossmassler on Sept 22, 2018 13:43:39 GMT -5
I agree, this set is looking good to me.
Regarding tire dimension specs - while there are some things out there, it has been damn hard for me to find tires for this period. Here in the states there is not a proliferation of clubs running these cars, so resources are not well known.
I have a few sets of PST wheels for this era, and the best tire fit I have been able to locate is the Scalextric for Vanwall/250F. So, Paul Gage, bless his heart, makes urethane replacements for this tire , and I bet they grip just fine, but are they actually big enough OD? (I haven't bought any yet). The Scalextric originals are only 23.5 OD.
The Scalex Restoration website offers rubber replacements for this tire, too, but the OD on those is only 22. They also offer an AutoUnion Type C MAXgrip, which is - darn it! - 7mm wide. (also not very attractive because of the oversize tread detail).
Scalex Restoration also offers 26mmOD MAXGrip replacement to fit a vintage Scalex wheel, but I don't know where or if that wheel is available. It is also 6.5mm wide and appears squarish.
Or, PCS offers the 32277 combo which looks pretty nice, but - arggg! they aren't urethane tires, they are also rubber. They also offer 32246, at 24 OD x 6mm wide. I suggest we allow rubber, so we could use these tire sets.
But, the general point remains, let's not make the tire specs so demanding that suitable wheel-and-tire combinations can't be found!
Thanks for all your work everyone!
-Max
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Post by Peter Seager-Thomas on Sept 22, 2018 14:08:20 GMT -5
I think the tyre dimensions will actually work out OK. The other tyres which are pretty good are the scaley ones for the Scalextric 'tinplate' Ferrari 375. These are (were?) not only done by Scalextric restorations, but george turner and Luf, up in Canada (look up 'old slot racer').
I'll look into posting a few fitted tyre sizes with added details on (visible) wheel diameters in the near future.
Peter.
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Post by maxrossmassler on Sept 22, 2018 15:13:44 GMT -5
Thanks Peter. I did check Luf's website, but there wasn't any link to any tires or other parts for sale. The website didn't look like it was recently maintained, but its hard to tell that sort of thing. I would love to buy tires from Luf, actually.
I think the PCS wheel sets will work OK for me. I am planning on doing a Type A Auto Union.
I know we don't actually have a planned event yet, but any impetus is a good thing!
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Post by EM on Sept 22, 2018 19:09:28 GMT -5
Found a website with tire specs for the 1939 w154/w163Mercede:*
Supercars.net
Front 5.25 X17
Rear 7:00 X 19
Assuming a "100 series" tire (carcass depth = width) this would correspond to, in 1/32 scale:
Front ((5.25 X 2) + 17)/32 = 0.86" = 22mm
Rear ((7X2) + 19)/32 = 1" = 25.4mm
Now, this was a late 30's car and the wheels and tires were trending smaller but one might consider either shaving the GP front tire spec to 22mm or adding the "universal out" - "exceptions allowed if the difference can be documented"
EM
* How authoritative? - don't know. Anyone have a copy of Pomeroy?
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Post by munter on Sept 22, 2018 20:45:06 GMT -5
I think that sorting the tire/wheel specs and a decision on motors and we are ready to talk dates and venues.
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