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Thread: 2016 Formula Student Germany

  1. #21

    Rim inploding

    Factory-P and all,

    Tire pressure when you inflate the tire....

    If you go on a racing circuit you will notice that race tire manufacturers do inflate the tire in a cage.
    Want a story? 15 years ago in the ALMS paddock, a Michelin service engineer, whom I knew from the late 80s in Formula 3, nearly lost his life.
    The tire did not exploded under the inflating pressure; the rim imploded! Rim manufacturing problem, lack of homogeneity in the casting of one of the spoke. Should have been seen in quality control but wasn't.
    A piece of rim clipped a piece of his ear. Another rim part went through the truck awning and was found in the paddock 400 meters from the truck. The guy could not hear for 2 weeks.
    If he would have had his head 50 mm away from where it was he would have been killed. Since that time Michelin and then others race tire manufacturers only inflate the tire in a steel cage.
    The Michelin race engineer is well and still working these days; I saw him at Le Mans 24 hours this year. But that day the gods where with him. Racing can be dangerous and not only on the circuit.
    Claude Rouelle
    OptimumG president
    Vehicle Dynamics & Race Car Engineering
    Training / Consulting / Simulation Software
    FS & FSAE design judge USA / Canada / UK / Germany / Spain / Italy / China / Brazil / Australia
    [url]www.optimumg.com[/u

  2. #22
    Junior Member
    Join Date
    Aug 2016
    Location
    Hanover, Germany
    Posts
    2
    Hello Julian and all,

    I am one of the development engineers of the Continental Tire.

    Firstly, I want to say that we at Continental feel very sorry for AMZ and HAWKS.
    We understand that this kind of DNF is very uncommon and especially disappointing for the teams.

    I would like to use the opportunity of this discussion to share some advice.
    I strongly encourage the teams to use rim contours that are PROPERLY designed for bead retention (i.e. contours with a standardized hump).
    There are standards available (e.g. ETRTO standards manual in Europe) that cover the aspects of rim design.
    Please have a look into it and consider it when designing your rims or purchasing new rims.

    @Julian: Unfortunately, your statement in the beginning already sounded a little bit like finger pointing (i.e. "the new Continental tires caused problems").
    Please let us consider the facts before claiming any responsibility! For example: Off-the-shelf rims don't necessarily have a hump.

    P.S: Regarding the mounting: The safety advice on our tires states to not exceed 40 PSI (275 KPa) to seat the beads. I know most people don't read until this point.
    But really: If the beads are not seated at this pressure, deflate, try again (maybe add some more lubricant). It's for your own safety!

    Best regards,
    Hannes
    Alumnus
    Baltic Racing
    UAS Stralsund

    2009: Head of Suspension & Vehicle Dynamics
    2010: Technical Director

  3. #23
    Hannes,

    I did not want to point fingers at all.
    Of course the teams are responsible for a functioning system when they "merge" buy-parts. Be that Conti tires or Keizer shells. The system must work and that's the responsibility of the team.
    Both teams seem to have "failed" here.

    Probably this is due to the fact that the (new?) Conti tire has some prerequisits to a rim that the teams don't know about from their previous choises, be it a 10" Hoosier or a Goodyear Eagle or the "old" Conti.
    Or maybe it is something else.

    I just wanted to point out that this issue did not seem to be a problem in former competitions. In fact, I witnessed all AutoX at FSG since ~2009 and never have seen a tire slipping of the rim of a "top" team.
    This year it happened twice. Both times with the Conti. So at least there is a link...

    I hope you guys continue in your great support of the Conti teams and hopefully you have a trick up your experienced sleeve to give the teams a tip, how they can prevent the same issue in Spain (and how to improve designs for 2017 ).

    cheers
    -------------------------------------------
    Alumnus
    AMZ Racing
    ETH Zürich

    2010-2011: Suspension
    2012: Aerodynamics
    2013: Technical Lead

    2014: FSA Engineering Design Judge

  4. #24
    Claude,
    Thanks for your insights on how Australian teams approach the competition.

    I too was pleasantly surprised by the track speed of the Shiyan car, both in autocross and endurance by the way.
    I was also impressed with the efforts and the team work by the Manipal team that has gone into trying to completely start over compared to their previous designs, and showing up with a 200kg car.


    Mostly unrelated, except that I only noticed because I went back to look at the Shiyan's final score, I think there might be a mistake in either the endurance or the efficiency scores of FSC:
    Washington, Wroclaw and Shiyan all finished 18 laps of endurance, but don't have an endurance score, which would indicate a DQ for whatever reason. However, all three of them do have an efficiency score.
    Either that is a mistake, or the mistake is that they got 0 points on endurance. Am I missing a third option?

    The FSE teams that got DQ'd after endurance (Ravensburg, Osnabrück, München UAS, Zwickau), all got 0 points on efficiency.
    Last edited by Thijs; 08-17-2016 at 09:58 AM.
    Alumnus
    Formula Student Team Delft

    2007 - 2008: Powertrain, Suspension
    2009: Technical Lead
    2010 - present: Grumpy Old Fart/Concerned Citizen

  5. #25
    Thijs,
    If I had to put my money down, I'd say they got a DQ and it was forgotten to remove them from the Efficiency results.
    Same thing happened so that GFRe was awarded the Efficiency Award at first before they where removed from the Efficiency event as well.

    (Just found it on Facebook:

    UWashington Formula Motorsports
    10 Std. ·

    FSG Final Results:

    Overall: 27th

    Design: 4th
    Skidpad: 9th
    Fuel Efficiency: 13th
    Business: 17th
    Autocross: 18th
    Acceleration: 22nd
    Cost: 73rd
    Endurance: DQ

    Unfortunately our team finished the endurance race but failed to pass the new re-scrutineering procedure. We thank Formula Student Germany e.V. for putting on such an amazing competition, and we look forward to competing in Germany again in the future!)
    -------------------------------------------
    Alumnus
    AMZ Racing
    ETH Zürich

    2010-2011: Suspension
    2012: Aerodynamics
    2013: Technical Lead

    2014: FSA Engineering Design Judge

  6. #26
    Senior Member
    Join Date
    Mar 2005
    Location
    Australia
    Posts
    1,633
    Quote Originally Posted by JulianH View Post
    ... a trick ... to give the teams ... how they can prevent the same [tyre de-beading] issue in Spain.
    Julian,

    As noted by others, the gold-standard is bead-locks as used by off-road racers (requires completely new rims), or else a slightly bigger hump on the rim (possibly by re-rolling the rim?), or self-tapping screws through the rim and into the bead (messes up your rims).

    My guaranteed-good approach in the past has been [... dramatic drum-roll...] ... GLUE! The rubbery "contact-cement" works well (read instructions, then apply between tyre and outer-rim), as does RTV-silicone (use "acetic-cure" (= vinegar smell) for faster cure than "neutral-cure").

    The only tricky bit is removing the tyre from rim. I suggest a big tyre-clamp, a sharp razor-blade, and much patience!

    Z

  7. #27
    Senior Member
    Join Date
    Dec 2009
    Location
    PERTH, Western Australia
    Posts
    201
    Lay some carbon/fibreglass around the bead, if you can spend the time to do a nice job it works well, as Z said, silicone is pretty good too, makes changing the tyre a paint though
    ex-UWA Motorsport

    General team member 2013-15, Vehicle Dynamics Team Lead 2012
    Project Manager 2011, Powertrain minion 2009/10

  8. #28
    Senior Member
    Join Date
    Sep 2002
    Location
    Perth, Western Australia
    Posts
    717
    Z, Julian (and others)

    Another solution for improving the bead on a metallic wheel is to use a few weld beads in a circumferential stitch pattern. A lot easier than re-rolling a purchased shell.

    After one particular year of leaking and painful rims at ECU wheel shells are now welded together and beads are built up with a little weld. No leaks, tyre slippage, or even a hint of debeading since. Tyres aren't always easy to install, but a small price to pay.

    Kev

  9. #29
    I have seen the contact cement method used successfully a number of times when the time / materials / skill / preparation aren't available. Removing the tire once it has been cured to the wheel is actually pretty easy. Yank out the valve and pour in the solvent / lacquer thinner of your choice and swish it around the bead. Wait half an hour and pop the tire off in the normal fashion.
    Jay Swift
    Combustion Powertrain
    Global Formula Racing 2013-2014

  10. #30
    Sorry to change the subject. But I've been speaking with the guys in my old team about design judging at FSG.

    Although, sadly Design Judging wasn't part of their focus this year (long story, but the reason we're talking about it is because I'm convincing them that it should be next year). They don't seem to think that FSG use this document, or follow the same structure for scoring in Design.
    http://www.fsaeonline.com/content/FS...et%20150pt.pdf

    I argued that surely they must be. But thought I'd ask on here, and get it from the horse's mouth.

    I think their main argument is that the judges they had weren't broken up the same way as the sheet, but rather covered different technical areas of the car.

    They believe they had 2 vehicle dynamics judges, 1 electronics, 1 aero, 1 driver controls & calibration, 2 powertrain, and 2 on chassis.

    This isn't a criticism, or a complaint, I wasn't there. But want to reassure them that they have the right information to focus on design for next year. So it would be good to get first hand clarification. Pat, are you around?
    Dunk
    --------------------------------------------------------
    Brunel Racing
    2010-11 - Drivetrain Development Engineer
    2011-12 - Consultant and Long Distance Dogsbody
    2012-13 - Chassis, Bodywork & Aerodynamics manager

    2014-present - Engineer at Jaguar Land Rover

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