X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 04 Oct 2009 19:20:43 -0400 Message-ID: X-Original-Return-Path: Received: from n2b.bullet.mail.ac4.yahoo.com ([76.13.13.72] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with SMTP id 3873829 for lml@lancaironline.net; Sun, 04 Oct 2009 07:46:42 -0400 Received-SPF: none receiver=logan.com; client-ip=76.13.13.72; envelope-from=casey.gary@yahoo.com Received: from [76.13.13.26] by n2.bullet.mail.ac4.yahoo.com with NNFMP; 04 Oct 2009 11:46:07 -0000 Received: from [76.13.10.170] by t3.bullet.mail.ac4.yahoo.com with NNFMP; 04 Oct 2009 11:46:07 -0000 Received: from [127.0.0.1] by omp111.mail.ac4.yahoo.com with NNFMP; 04 Oct 2009 11:46:07 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 527845.28701.bm@omp111.mail.ac4.yahoo.com Received: (qmail 47569 invoked by uid 60001); 4 Oct 2009 11:46:07 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=dkyQvPUINxtE+Qs5J/dQajpzIloY6lEXn2fnmnKE7yUkFff6aaST7UNiOlMi6UrhfsffZOMJhFpRAvh5j72P2RNvJHLsEGb0V+FqiMgqzdu0zS6vzazHlfIfSBLgrGTRY5TWnh4X73Fo672CZ/FAeqprNT6dxvk2BT0CtLANflI=; X-Original-Message-ID: <390753.47372.qm@web57511.mail.re1.yahoo.com> X-YMail-OSG: N8UL_AIVM1ko_VOrWVdNq2JLUFBPclkk1OTiQgI13F7aCFxJx5OyUlTnOp_528bNlsOiacmyiku5Q_QPIQXKQBEB9s4Owl5ZSQZWTfOfRgBkUdp34s6YERDiJTvDlU3DrydfyLspb3wJ5JmiH8t9UHOy5NRdL2aUP5K_n2egbnx_JC1oAgLHj9tw6mSz0pT7UcwJNCBIZMqQgX8OAjq1FSS2cg8OgUo..ZqbIlpMfLEJBab8.UdB_I831_KszTeBCksBEQohhJ.5KHT90SDhxfkGfJhpEJsRH7xg6O9tHavkkXpDJVgAxHOX_RZfDH3T_5sbqg7Hg_1f6ZY- Received: from [97.122.189.50] by web57511.mail.re1.yahoo.com via HTTP; Sun, 04 Oct 2009 04:46:06 PDT X-Mailer: YahooMailRC/157.18 YahooMailWebService/0.7.347.3 References: X-Original-Date: Sun, 4 Oct 2009 04:46:06 -0700 (PDT) From: Gary Casey Subject: Re: Beringer wheels and brakes on a 235 X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-807566447-1254656766=:47372" --0-807566447-1254656766=:47372 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Just to put in perspective, I calculated the energy to be absorbed with a 2= ,000 pound vehicle in a stop from 80 mph. It comes out to 214,000 ft-lb pe= r brake, so it is right in the neighborhood of what is claimed for either o= f the brakes. What isn't said is the initial and final rotor temperature a= ssumed. The capacity of a brake is directly related to the mass of the rot= or - this can't be compromised. Of course, the hub of the rotor isn't part= of the calculation and on a conventional brake that mass is essentially wa= sted. And there are two factors to consider: Specific torque (ft-lb torqu= e/psi) is proportional to the friction coefficient, effective diameter and = piston area. Just rating a "torque capacity" without giving the pressure r= equired to get that torque doesn't tell me much. Energy capacity (ft-lb) i= s proportional to the temperature rise, rotor mass and rotor specific heat.= When someone talks about "stopping power" I'm not sure what is meant. Any brake/master cylinder combination should have the ability to l= ock up the wheels with a reasonable pedal effort, but that has nothing to d= o with the energy capacity.=0A=0AAccording to the posted numbers the Bering= er brake will end up at a higher temperature after a given stop, with a 24%= higher temperature rise. Would the higher temperature result in fade at t= he end of a rejected takeoff? Does that equate to a shorter pad life? May= be, but is that a reasonable trade-off for the lighter weight? Probably - = in my opinion, anyway. The Beringer brake will require 12% more pedal effo= rt for a given torque assuming both were rated at the same pressure. Is th= at enough to be important? Does the ligher weight justify the higher price= ? Only the buyer knows that.=0AGary=0A=0A=0A=0A___________________________= _____=0A=0A=0AWhen I looked at them, I compared them to Grove=E2=80=99s whe= els in=0Abrakes in terms of stopping capability (claimed). Data sheets are= dubious=0Ato me when a company is trying to sell something, but this is wh= at I=0Aread: Grove shows around 4700 in-lbs, while Berigner is 4200=0Ain-l= bs. Grove says they are capable of dissipating 246,000 ft-lbs of=0Akinetic= energy while Beringer shows 198,000 ft-lbs (5 inch wheels and brakes=0AGro= ve PN: 57-224, Berigner=E2=80=99s part number: JA-31, Legacy=0Ainstallatio= n). 198k ft-lbs is still respectable, but I wanted the extra=0Amargin.=0A = =0AWho knows what the real numbers are, but Grove appeared to be better in= =0Aterms of stopping power. Is this true? I don=E2=80=99t really know,=0A= because I don=E2=80=99t have a dyno to hook them up to. =0A =0AI could be = reading this wrong, but it also appears Grove is lighter as=0Awell. The da= ta sheet isn=E2=80=99t clear whether or not the 7.2 lbs is for=0Aboth wheel= s or just one. I think it means 7.2 lbs for both compared to=0ABeringer=E2= =80=99s 4.25lbs for one? It=E2=80=99s not too clear if that is the=0Acase.= =0A=0A=0A --0-807566447-1254656766=:47372 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Just to put in perspective, I calculated the energ= y to be absorbed with a 2,000 pound vehicle in a stop from 80 mph.  It= comes out to 214,000 ft-lb per brake, so it is right in the neighborhood o= f what is claimed for either of the brakes.  What isn't said is the in= itial and final rotor temperature assumed.  The capacity of a brake is= directly related to the mass of the rotor - this can't be compromised. &nb= sp;Of course, the hub of the rotor isn't part of the calculation and on a c= onventional brake that mass is essentially wasted.  And there are two = factors to consider:  Specific torque (ft-lb torque/psi) is = proportional to the friction coefficient, effective diameter and piston are= a.  Just rating a "torque capacity" without giving the pressure required to get that torque doesn't tell me much.  Energy capacity (f= t-lb) is proportional to the temperature rise, rotor mass and rotor specifi= c heat.  When someone talks about "stopping power" I'm not sure what i= s meant.  Any brake/master cylinder combination should have the abilit= y to lock up the wheels with a reasonable pedal effort, but that has nothin= g to do with the energy capacity.

According to the= posted numbers the Beringer brake will end up at a higher temperature afte= r a given stop, with a 24% higher temperature rise.  Would the higher = temperature result in fade at the end of a rejected takeoff?  Does tha= t equate to a shorter pad life?  Maybe, but is that a reasonable trade= -off for the lighter weight?  Probably - in my opinion, anyway.  = The Beringer brake will require 12% more pedal effort for a given torque as= suming both were rated at the same pressure.  Is that enough to be important?  Does the ligher weight justify the higher price?  = ;Only the buyer knows that.
Gary


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<= span style=3D"=0Afont-size:12.0pt;">When I looked at them, I compared them = to Grove=E2=80=99s wheels in=0Abrakes in terms of stopping capability (clai= med).  Data sheets are dubious=0Ato me when a company is trying to sel= l something, but this is what I=0Aread:  Grove shows around 4700 in-lb= s, while Berigner is 4200=0Ain-lbs.  Grove says they are capable of di= ssipating 246,000 ft-lbs of=0Akinetic energy while Beringer shows 198,000 f= t-lbs (5 inch wheels and brakes=0AGrove PN:  57-224, Berigner=E2=80=99= s part number: JA-31, Legacy=0Ainstallation).  198k ft-lbs is still re= spectable, but I wanted the extra=0Amargin.

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Who knows what the real numbers are, but Grove appeared to be better = in=0Aterms of stopping power.  Is this true?  I don=E2=80=99t rea= lly know,=0Abecause I don=E2=80=99t have a dyno to hook them up to.  <= /span>

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I could be reading this wrong, but it al= so appears Grove is lighter as=0Awell.  The data sheet isn=E2=80=99t c= lear whether or not the 7.2 lbs is for=0Aboth wheels or just one.  I t= hink it means 7.2 lbs for both compared to=0ABeringer=E2=80=99s 4.25lbs for= one?  It=E2=80=99s not too clear if that is the=0Acase.=

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