X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 18 Apr 2012 15:34:42 -0400 Message-ID: X-Original-Return-Path: Received: from nm15.bullet.mail.sp2.yahoo.com ([98.139.91.85] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with SMTP id 5487487 for lml@lancaironline.net; Wed, 18 Apr 2012 14:45:47 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.91.85; envelope-from=chris_zavatson@yahoo.com Received: from [98.139.91.66] by nm15.bullet.mail.sp2.yahoo.com with NNFMP; 18 Apr 2012 18:45:11 -0000 Received: from [72.30.22.33] by tm6.bullet.mail.sp2.yahoo.com with NNFMP; 18 Apr 2012 18:43:11 -0000 Received: from [127.0.0.1] by omp1061.mail.sp2.yahoo.com with NNFMP; 18 Apr 2012 18:43:11 -0000 X-Yahoo-Newman-Id: 357470.65420.bm@omp1061.mail.sp2.yahoo.com Received: (qmail 65369 invoked from network); 18 Apr 2012 18:43:10 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=DKIM-Signature:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Subject:References:From:Content-Type:X-Mailer:In-Reply-To:Message-Id:Date:To:Content-Transfer-Encoding:Mime-Version; b=Ta8WgVNm52lkE2usMjs4XScl09Hp9ZiKle03aFJQOKfkGlnfljsCMQD5dniA3cIjiOof0Paiuh0sNV+Z91Vv2YovFcoDLgW5g+Fg67Q5oPfLPnektL3G/+Pp6W3ZcD9hgZZBK4ktLgson64P3NuRLb2VUjZvAOY4SbyxDI4mOWY= ; X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: Rz8dHYwVM1mXeituE2YQICuW5twaCPFLqNnKXw7ZQe.w8Oh xP_BGcpsJ5Bu4ezUyAOfs5W51ihsH52osnmIE3kB.v28dRX5cY5bOIHaU2yT tY.sF2MI83ZlI8X5tEqduTjAmeRt0zVTfg8EDiTMGyUXh_.bhCazXOb3M97F An.smHLjICyF7plZIOppIkI9n1bJkn2CC4zgBBHszO2.YRpyKyLmvAymbJP. OAs_8Xyyqt1XDvj0aWydJQFOhChOU97CqrdpZpeEh1FV91FEP7YAB99iej3t AWQbkiovirIhzCvEpyj8O4YSSyBnv46J40PNTNq3H9uHMHQr5aG00yw89eMM OFp.tzV.guq2ok1S6FgdrTRxY3WO9Xb4WRsu_vZ5MwsHgdIJ7aCMGTqomXrC n_45QlztIw17yCMrgdAzAEjq8FwlogLhuEIhdxJVK0YyzCISneYX467_k6rr Urcr0XXTS3j1WF56GoDfEhdEaO6vu1Jz76JShkqIJTwermHUgSk8WdA0NJby G6y5pBdhXr.2VMzqKPNm5K1aqUQkVnPCg.zHxs6GRzHAQRq.1pmpc71Vl.6j NrFe5aNEtSGW_n.Dd_b1FBxYLzcZXkn73pm02XGgUA1EBn3lj58juT0jU2xJ h0IYb5tfW7tfaJ8dtDyoXydgIn_S151.Ic03pG8hluJUyDAiCsr_DyI9vBrs pgmXE0egrHP_mqJn6a5KUB3DP94U3vt89FDsNiQ61C1.kz4dPfT9HjmmaIQX uZiDqCkxZN5ApuUUxWqkpCNnudI_9AVr.risK1UCigYG_lbgViZ.SRaU5WJ9 R1T6ZrbIMa89KDfYWDXc85n75p2EVLEddQjhQcDqRKiiCzjj_Q7D9ZAKtjcA AZpbOTTa3Nt2vBCUoB7KUaQtR8HBnCdrCMafULapPslMtDGxfQjyglJcj27X n5w54lOZFEqTzOcIgdOHZJpzaHT7brKD.trc.yK.X5ar7om_lChYSTfMeSZS YOt77ER_yH0Ieun7cvKYPzEEBXKNhzuhNrEgFa_vjteDl4gtMFoJF0CARuAV BtDhRkzvIgNNi8fERtYp1E_z.Lk4FPfCDI56co01HSkV1F7ELyYVbvg1Fztq VBQsKvyCnEqmzaZdz58YXYyU54uFgoUMtC.s8DSkj0yeFeqrdMWAtaDC3y0O i0mOOOjIbV8ZvoYFlz0bklafYFy0Pype70xD2RuissVAdrD9E0OxK_bqicQ8 V6j0M0iO_E28y.ogUmGCJ5DJe_igbTZ2Trab4OVHPWXgeMg19ENjriqskZV7 ROeJwgKyhMpzTzsU_MVpZ9iDSKexMocaDbOgnQW3UQxVjzwHj3BEHdeaSBmA pv2O1x63l3ZVPpTDU_0dPhd0N7fbVmx6wS12l3JMF8McxPDTF0f02q_nql.d gADudC.JbZ0rW7akAS1pqX3lSzw2YJd6gi_SLX0gqdagHqRikoE1l5800DoX cZuQfVXKHUs4V94zC_cpj4qs.zQnBBQdy4Rr7Apw2lXVBd3LIGDKams9JBVk hgjCfbFGKcySdSLh169ED5IHE0nJbpkFSRVjmUvRMIk48QEYVtVDe_QPY378 dUxNmrKYzItW6PuBwJy9_CBxRnrEyjDURkigG9NTwvut4hUZ2DtL2kLDFLKQ fiGPMkqRJa3CNzFg75m4OcXLnPHSPOcFxlswe34BSDA0n0RftVCAsRP0Tczu P16XoUTAZv7pclaBy X-Yahoo-SMTP: 076hgjCswBC.G6e0vm7vgvZ9JJ0zmeBo_Oyw Received: from [10.122.246.207] (chris_zavatson@166.205.138.70 with xymcookie) by smtp124-mob.biz.mail.gq1.yahoo.com with SMTP; 18 Apr 2012 18:43:09 +0000 UTC Subject: Re: [LML] Re: Excessive down hydraulic pressure References: From: Chris Zavatston Content-Type: multipart/alternative; boundary=Apple-Mail-A173DA4D-B121-4800-84CD-B607EC67F3DE X-Mailer: iPhone Mail (9A405) In-Reply-To: X-Original-Message-Id: <448D9CC1-E033-4787-A037-CCC823D31E37@yahoo.com> X-Original-Date: Wed, 18 Apr 2012 11:43:04 -0700 X-Original-To: Lancair Mailing List Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-A173DA4D-B121-4800-84CD-B607EC67F3DE Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Adam, Wow, I looks like you are venturing into some uncharted territory - both in d= esign and now troubleshooting. Your hydraulic schematic is the place to sta= rt. The recorded time history of pressure is a really neat tool to have. Chris Zavatson N91CZ 360std www.N91CZ.net On Apr 18, 2012, at 10:01 AM, Adam Molny wrote= : > Hi Jeff =E2=80=93 > =20 > Yes, I=E2=80=99m using my Sequenced Gear System in this plane. The inner g= ear doors close after the landing gear is extended for landing. I can say fr= om experience that it provides a huge reduction in wind noise and cockpit dr= afts. Naturally I investigated whether my system could be contributing to th= e problem. During system development I changed to a down pressure switch wit= h a set point of 650psi. The stock 550psi switch didn=E2=80=99t provide enou= gh =E2=80=98oomph=E2=80=99 to close the inner gear doors against the emergen= cy opening springs. I have an older kit with the narrow diameter door cylind= ers. Customers with the newer style large-diameter cylinders are able to use= the stock pressure switch. > =20 > Theoretically, having a down pressure with a higher set point should help a= lleviate this problem since the system would be less sensitive to pressure b= uildup on the down side. I believe we can also rule out pressure buildup due= to thermal expansion. My early flights never went above 5000=E2=80=99 so th= ere wasn=E2=80=99t a big temperature swing. Also, you would expect to see a g= radual rise in pressure due to cold soaking, which wasn=E2=80=99t the case. > =20 > Partway through the build process I also modified my hydraulic pump by ins= talling the high capacity impeller. > =20 > As part of the troubleshooting process I have removed the inner gear door s= prings. The gear still extend quickly in both ground and flight tests as see= n in my fourth flight video. http://www.youtube.com/watch?v=3Dfo1qnhBuqS8. W= hile developing the sequenced gear system I learned that the pressure switch= es can be wildly inaccurate, and they behave oddly at the limits of their ad= justment range. As you turn the adjusting screw to increase the pressure the= hysteresis decreases. In other words, the pressure difference between turni= ng off and turning back on again gets smaller. This can lead to pump chatter= where the gear hit their stops, the pressure rises and the pump shuts off. T= hen the pressure drops slightly and the pump kicks in again. This can happen= several times per second and last several seconds. The solution was to make= sure the adjustable pressure switch was set near the middle of its pressure= range. > =20 > I don=E2=80=99t have a solution yet but I=E2=80=99m reading through Chris Z= avatson=E2=80=99s excellent write up on the Lancair hydraulic system http://= www.n91cz.com/Hydraulics/Lancair%20Hydraulics.pdf. I=E2=80=99m beginning to s= uspect a sticky shuttle valve or some other internal pump problem, with the p= ressure switches as a secondary suspect. On my fifth flight yesterday I had t= o crack the dump valve to get the doors to close completely with the gear re= tracted =E2=80=93 and this was with the door springs removed! > =20 > -Adam Molny > 7.6hrs Hobbs time and counting > From: Jeffrey W. Skiba [mailto:jskiba@icosa.net]=20 > Sent: Tuesday, April 17, 2012 9:52 AM > To: lml@lancaironline.net > Subject: RE: [LML] Excessive down hydraulic pressure > =20 > Adam, > =20 > Are you running the Stock Lancair gear system or are you using your gear s= ystem ? > =20 > Do you have the first generation pump or the high capacity one ? >=20 >=20 > TODAY(Beta) =E2=80=A2 Powered by Yahoo! > Amazon's big knock-off problem > Privacy Policy >=20 > =20 --Apple-Mail-A173DA4D-B121-4800-84CD-B607EC67F3DE Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Adam,
Wow, I looks like you are = venturing into some uncharted territory - both in design and now = troubleshooting.  Your hydraulic schematic is the place to = start.
The recorded time history of pressure is a really neat = tool to have.

Chris = Zavatson
N91CZ
360std
<= br>On Apr 18, 2012, at 10:01 AM, Adam Molny <Adam=40ValidationPartners= =2Ecom> wrote:

<=21--=5Bif =21mso=5D> <=21=5Bendif=5D--> <=21--=5Bif gte mso 9=5D> <=21=5Bendif=5D--><=21--=5Bif gte mso 9=5D> <=21=5Bendif=5D-->

Hi Jeff = =E2=80=93

 

Yes, I=E2=80=99m using my Sequenced = Gear System in this plane. The inner gear doors close after the landing gear is extended for landing. I can say from experience that it provides a huge reduction in wind noise and cockpit drafts. Naturally I investigated = whether my system could be contributing to the problem. During system development I = changed to a down pressure switch with a set point of 650psi. The stock 550psi = switch didn=E2=80=99t provide enough =E2=80=98oomph=E2=80=99 to close the inner = gear doors against the emergency opening springs. I have an older kit with the narrow diameter door cylinders. Customers with the newer style large-diameter cylinders are able to use the stock pressure switch. =

 

Theoretically, having a down = pressure with a higher set point should help alleviate this problem since the system = would be less sensitive to pressure buildup on the down side. I believe we can also = rule out pressure buildup due to thermal expansion. My early flights never went above 5000=E2=80=99 so there wasn=E2=80=99t a big temperature swing. Also, = you would expect to see a gradual rise in pressure due to cold soaking, which = wasn=E2=80=99t the case.

 

Partway through the build process I = also modified my hydraulic pump by installing the high capacity = impeller.

 

As part of the troubleshooting = process I have removed the inner gear door springs. The gear still extend quickly in both ground and flight tests as seen in my fourth flight = video. http://= www.youtube.com/watch?v=3Dfo1qnhBuqS8. While developing the sequenced gear system I learned = that the pressure switches can be wildly inaccurate, and they behave oddly at the = limits of their adjustment range. As you turn the adjusting screw to increase the pressure the hysteresis decreases. In other words, the pressure difference between turning off and turning back on again gets smaller. This can lead to pump chatter where the gear hit their stops, the pressure rises and the pump shuts off. Then the pressure drops slightly and the pump kicks in again. = This can happen several times per second and last several seconds. The solution = was to make sure the adjustable pressure switch was set near the middle of its pressure range.

 

I don=E2=80=99t have a solution yet = but I=E2=80=99m reading through Chris Zavatson=E2=80=99s excellent write up on the Lancair hydraulic system http:= //www.n91cz.com/Hydraulics/Lancair%20Hydraulics.pdf. I=E2=80=99m beginning to suspect a sticky shuttle = valve or some other internal pump problem, with the pressure switches as a secondary = suspect. On my fifth flight yesterday I had to crack the dump valve to get the = doors to close completely with the gear retracted =E2=80=93 and this was with the = door springs removed=21

 

-Adam = Molny

7.6hrs Hobbs time and = counting

From: Jeffrey W. Skiba =5Bmailto:jskiba=40icosa.net=5D
Sent: Tuesday, April = 17, 2012 9:52 AM
To: lml=40lancaironline.net
Subject: RE: =5BLML=5D = Excessive down hydraulic pressure

 

Adam,

&nb= sp;

Are you = running the Stock Lancair gear system or are you using your gear system = ?

&nb= sp;

Do you = have the first generation pump or the high capacity one = ?

= --Apple-Mail-A173DA4D-B121-4800-84CD-B607EC67F3DE--