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Thread: Build my own sucker car

  1. #11
    the main problem you've got to watch for, if you get it to work, is sudden loss of suction. if you're pulling 3G cornering and lose suction, em... enjoy! i think suction cars are great, and the alan staniforth book is good. if you read closer, the car wasnt banned, they retired it on a gentlemans agreement. basically they couldnt ban it because they proved that 70+% of the airflow generated was required to cool the air cooled V12. also turns out they won by overtaking on the outsides of corners . and Z, you're right, it was Sweden 1978.

    hmmm... air cooled CBR600 anyone?
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  2. #12
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    Quote by Psychosis "main problem... is sudden loss of suction."
    ---------------------------------------------------------------

    The accounts of the Chaparral 2J suggest that this is not too much of a problem. The 2J had skirts just behind the front wheels, down each side (enclosing the rear wheels), and across the back - it was a very box-shaped car. It sucked the air out of the "engine room", which in effect formed a large plenum. So when the skirts hit bumps and momentarily stopped sealing the downforce was only lost gradually - apparently slowly enough that the driver could feel it and make appropriate corrections. However, after each race the engine bay was filthy with dust, rubber particles, etc.

    I did a quick google for industrial fans and it seems that very simple "radial vane" or "backward curved vanes" (just fabricated sheet metal) centrifugal fans can give a pressure differential of 20-30kpa (2-3tons/square metre) with efficiencies around 80%.

    So, remember the old saying - "Be careful what you wish for - you might get it!"

    If you do get it working well, I can picture exploding tyres, broken axles, etc., etc... (although still fun!).

    Z

  3. #13
    Road and Track did run a challenge. They actually ran two events.It was to become an annual event but just fizzled out. Too bad.It was a really cool challenge. If they ran it again I would be there in a minute. It's purpose was to determine the "ultimate cornering car".Several types of sports cars,race cars, an enduro kart and two purpose built cars showed up. Both purpose built cars were sucker cars. I believe one suction system was driven from the main car engine, the other car system used one or two lawn blowers.There were some carburetion difficulties with the engines caused by the cornering forces. I also recall reading that when the suction was turned on on one of the cars before moving it just sat there and slipped the clutch. I believe that the winning car created just under 2 G's of cornering force.(This is all memory from a few years ago so the accuracy may be a bit fuzzy.) I was, and still am really interested in building one,except I just can't imagine designing and building a car that I couldn't race anyone with....
    Regards
    Bryan
    Originally posted by John Bucknell:
    Z's got the right idea. A few years ago Road & Track (I think) ran a skidpad challege, and the Bowlands showed up (Todd went to VT around 1991 and they build their FSAE chassis to be a sucker until Cornell got it outlawed ) with their tube frame autocross terror (big wings) and two leaf blowers hooked up to a sucker system. Ended up riding on the jounce bumpers I might have it in my archive somewhere. Their skirts were lexan 'flaps' I think that just dragged on the ground.

    I'm designing a sucker car for my own enjoyment as well, and the research I've done says you need a huge planform area and relatively little leakage (10mm gap) to develop significant downforce on a 1000 kg car (ie 1g additional). Ends up having to move a lot of air, and I think two-stage axial flow fans will actually do a better job than a centrifugal (try the Multi-Wing Optimizer to size a fan, you can get it for free @ download ) for the flow rates you'll need. Of course, if you can get a better seal - then the flow rate goes down.

  4. #14
    Well, a little digging and I found the article via R&T's annual index on-line. It is in the Feb 1996 mag on p92-97. Lots of pics, big wings and three vacuum-assisted cars (plus one vacuum kart). Winnig two-way average with Todd Bowland driving was 1.98g on a 200 ft circle. If I can figure out how to scan the article, I'll post it.
    John Bucknell

    FSAE since 1990 - Design Judge since 2003
    Scrutineer: SCCA ProRally/Formula One
    General Know It All
    /Performance Development Engineer

  5. #15
    the chaparral actually used lexan skirts...but another car too look at would be the 1978 brabham bt46b which won the swedish GP on its introduction day...
    Micah McMahan
    Freelance Design Engingeer
    Former MSI Defense Solutions - Sr. Design Engineer/Project Manager
    Former Roush Yates Engines - Sr. Design & Analysis Engineer
    3MI Racing LLC Owner/Engineer
    ODU FSAE 04 member, 05 controls leader, 06 control/ergo/brakes leader, 07 brakes/MC22 turbo engine/Asst Team Leader

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