From the race director, proposed pit area organisation.
Keep voting for your top 3 cars. Someone can start a numbers racket 🙂
(poll linked on blogroll)
Allan from Carmanah sent me this image and movie of our car, taken on practice day 2006. The car wasn’t quite finished, no paint, brakes, axle fairings or wheel covers. Still looks pretty good, I think on that day we were hitting between 34-35 kph at corner (seen at end of vid). My god the YouTube interpretation of the video is awful, Allan’s original file is much better quality.
I’m using so called “sealed” cartridge type bearings in our car’s wheel hubs. They are not as free running (under no load conditions that is) as good cup and cone hubs, and they tend to bind slightly when pre-loaded too much by hub retaining nut. I’ll look into removing rubber seal from bearings and I wonder if they need to be “run in” for a few hundred miles 🙂
See here for an interesting discussion on bearings.
An afternoon of drinks and chat today with other Canary Derby teams. A highlight was the demonstration of a wireless timing system designed and built by Archipeligo. Its a pretty slick set up, they get my vote for best tech innovation.
Seeing as it is only 2 weeks from the practice day, and seeing as we were all having a drink, the details of our car designs started to dribble out. Different approaches, from low profile to high. By the way, if anyone would like a custom made water tunnel as seen in that linked article, drop me a line.
Here are some early construction pics of our (Aspreva) car. You can see the pan view is a symmetric airfoil shape. A curved fiberglass fairing will cover the top and bottom plywood “plates”. The driver is totally within the car, looking out front through clear Lexan front (the open areas).
Its about 112″ long, max width 19″, height as shown is 19″, but body will be higher by about 4 inches when top and bottom fairing applied. Wheels are 27″/700c, road rims with mountain bike hubs (20mm axle), discs on rear wheels (Avid BB5), moderate tires (28 mm Panaracer).
It’s about time I publicly acknowledge the help we have had on the construction of our car.
Fairfield Bicycles – Richard and Max helped with the wheels and brakes, and with great technical advice. I think they are the best bike shop in Victoria.
University of Victoria – chemistry and physics machine shops – thanks to JP & DS for advice, and especially JP for the works of art (custom stub axles).
Metals Supermarket – big thanks again this year to Mark for metal supplies.
Slegg Lumber – thanks to the Sooke outlet, for the plywood.
Acura Plastics – a discovery for me, good tech advice and plastics source.
West Marine – Sidney store – helped with epoxy resins and fiberglass cloth.
Victoria is a nice town, sure it is, but sometimes…
Was looking for 3/8″ UNF lefthanded thread nuts. Tried major fastener outlets, tool and equipment supply place, and a big hardware store. Nope, might as well be asking for a muffler valve.
Ended up borrowing a tap from secret source.
Tip: if you have to make your own 3/8″ nut, UNC or UNF, left or righthand thread, take a 5/16″ nut and drill the threads out with a 5/16″ drill. This gives a pretty good hole for a 3/8″ tap.
Remember to use cutting oil and back off every part turn to clear the chips.
Despite best intentions it all comes down to a mad rush to finish building the car. This drizzly long weekend is all about constructing the axle mounting system. Things to keep in mind are:
-accounting for any flex in chassis, or eliminating flex
-provisions for axle adjustments
Our car is designed so that the axles are a sub-assembly of the main chassis. Other car designs may have the axles and mounts as integral with the chassis – so the above points may have been taken care of already.
My approach in axle design differs slightly from what is outlined in the “soapbox construction manual” (linked in share box on sidebar) in that I am discounting the need to account for axle flex in the mounting system. There will be some flex in any system, but I theorise that with beefier axle members and pneumatic tires, road shock will be taken up mainly by the tires rather than the axle itself. If you are using solid tires and solid wheels then road shock will be translated almost entirely into axle flex.
Consistent with this approach is our goal to eliminate (or at least reduce) any chassis flex. As a side note, the photo of the Canamera/BC Cancer Agency car shows a very low ground clearance. I am sure the designers have done their homework on the shape and angles of the launch ramp and speed bumps, but it looks close to the limit before grounding out. In their case chassis flex would be quite unfavourable 🙂
Spending the afternoon shaping blue Styrofoam for part of our car. Its one of the worst jobs. Using handsaw, slim carving knife, random orbital sanders (80 and 150 grit, and connected to shop vac), its a messy business. The Styrofoam chips and dust floats then sticks everywhere. Having a shop vac connected to the sanders is a definite requirement.
Another thing I hate about styrofoam is how it seems to take a “set” when sanding. Hand sanding in one direction sets up the foam cell structure to rip when the sanding direction is changed. This often happens when you are doing the final touch ups.
As I carve away, I am thinking bad thoughts about those fortunate teams that have access to a 3 axis CNC router – you know who you are.
Video from Goodwood race a few years ago. Notice smaller car gets away first, but taller car catches and passes. Is this due to better wheels, aerodynamics or better cornering?
Also notice the penalty of having a higher centre of gravity (second race).
(video’s owner does not allow embedding, so you have to click on link to watch on YouTube site)
They unveiled their car today at a press conference in the Deeley Cancer Centre. I was too late getting there to see it, but I did catch a glimpse on the local 5 o’clock news (A Channel). The car looks pretty darn good, low (in-fact quite low, 2″ ground clearance?), body formed front and rear to allow such a low car to transition off the ramp, ackerman/king pin steering, est. 18″ wheels, and an overall wedge shape, (well it looked more wedgie in the TV feature, doesn’t show as well in pic).
Wonder how many bulders out there have their cars built, ours (Aspreva) not finished, but hey, one month to go!
I’m wondering if any of what I have wrote or linked to has been of any use to you out there at the end of the “tubes”. Let me know in the comments.
I haven’t decided whether the builders meetings make me more or less nervous about the race. Anyhow, here are some points mentioned yesterday that I found important.
-total of 21 teams entered
-some of the new teams at meeting, very enthusiastic.
-Camosun College entering team, they have extensive fabrication facilities (grrr)
-finish line will be crosswalk out back, out of bounds (ie stop car before) will be speed bump further on (over 200 feet).
-race day will be busy, approx 65 races in total. Will be a challenge to turn cars around and back up hill in short time.
-they need volunteers desperately!!
-race teams supply crew at finish to load car
-entire team must sign release, only team members in pit area
-drivers sign release too and must be there early (9am or before) to have meeting with director
-drivers will be weighed and given wrist band with weight and ID to wear.
-we won’t be carrying cars up to start via stairs, have to push car around the “long way” (you know what i mean).
-it will be much better organised as to calling cars for race etc.
-each car gets at least 4 runs, 2 in morning, 2 in afternoon.
-best total times (inside and outside lanes) is what counts (like last year)
-radar gun will be positioned at corner, so will get speed to, and away from corner.