X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iw0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4472546 for flyrotary@lancaironline.net; Sun, 19 Sep 2010 11:48:47 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=msteitle@gmail.com Received: by iwn8 with SMTP id 8so4619112iwn.25 for ; Sun, 19 Sep 2010 08:48:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=l02ZiRoZ+dTufRpzvKh2EJx2HKMPL5pLI4fmzyRfGTs=; b=fSyvbknZ5nXTQxUtrL4nlXEbopdMRCaosOsmD6tAyPrCyK6Wg+KsyZa5/WyhvWlU31 74e9Sq72gH/YHoZXrD3So4uz5I5HqFFE2Oj8X+vEoA02/Ws9UbLGundCM6WB15ClyeVm ooc5HeFT3YtlYZy0FKCEyJ9KgmtpUxYmIBSq4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=pJCf6naCHCG26ig3dne6piamTg3cpdHEYBNqw030tRN+DV50pltqrJlTF+kaWkljZP acrCkms9zl0KYJdAXHf/DlldltFtKHYpziYBvhXLX9K5e5cByvM7e2c/Azt4162/iS72 IrLW1aN6MAz2fCuTNGm8ejRc504ezaxSpVAHg= MIME-Version: 1.0 Received: by 10.231.13.140 with SMTP id c12mr8781771iba.25.1284911291649; Sun, 19 Sep 2010 08:48:11 -0700 (PDT) Received: by 10.231.173.137 with HTTP; Sun, 19 Sep 2010 08:48:11 -0700 (PDT) In-Reply-To: References: Date: Sun, 19 Sep 2010 10:48:11 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Check PSRU Oil Drain-back hose was Re: Watch that psru oi... From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=002215046ae31b53ac04909eb942 --002215046ae31b53ac04909eb942 Content-Type: text/plain; charset=ISO-8859-1 Lynn, Yes, that all makes perfect sense. This is the first time I really opened up the p-port 3-rotor. So, it makes sense that this is when the seal would fail. I have a secondary vent that I plan to install before next flight. Thanks for sharing your knowledge of the rotary with the group. Mark On Sun, Sep 19, 2010 at 10:09 AM, wrote: > In a message dated 9/19/2010 9:19:17 A.M. Eastern Standard Time, > msteitle@gmail.com writes: > > Ed, > > You and Lynn may have hit on something regarding the crankcase vent line > being too small. It may have been marginally acceptable with the side port > engine, but way undersized for the fire-breathing p-port. First time I ran > it real hard, out came the seal. I am using the stock vent line, but will > go ahead and up-size it while I'm fixing the psru seal. > > Mark > > The engine and PSRU are a pressurized system at about the same pressure. > The engine is pressurized by blow by combustion gasses leaking past the side > seals and oil scrapers. The PRSU is pressurized to the same value through > the oil drain-back line. So, drain back would be impeded to some extent > until the pressures are equal. After that it would be a constant until a > power change is made that increases or decreases blow-by. Since the volume > of the PSRU is so small it could be discounted as a drain-back problem, but > the same pressure as the crank case will still be present. And that pressure > added by the volume of lubricating oil (at 70 PSI or more) for the bearings, > though not a large factor when the drain back hose diameter is adequate. > > Some builders use the factory side seal end play specification, allowing up > to .004". I use zero end play in side seals. I install them tight, and then > reduce length until the side seals and corner seal will just pop back up > after being fully compressed into the rotor. The side seal is being pushed > along by only one side of the corner seal. The seal end wears into the > corner seal in short order. This starts making clearance right at break in. > The direct outcome, is nearly zero blow by. Pressure not lost to blow by, is > free HP. > > This does not apply to Renesis engines where the side seal is exposed to > exhaust gas flow and needs extra clearance to survive. (Because it runs > hotter and gets longer). > > Let us say that our engine has normal blow by of 12 cubic feet per minute. > The stock breather pipe in the filler tube is smaller than 3/16". This means > the gas velocity out of that pipe and into a catch can may be very high. So > rich in energy that it can evacuate large amounts of oil droplets in the > catch can. So, you make the vent pipe as large as is practical. That same 12 > cubic feet, or more, still escapes, but now the crank case pressure is lower > (less restriction) and gas velocity is way down. Down on energy and velocity > the escaping gasses can no long lift oil droplets and drop them into the > catch can. The catch can must have at least 5 times the open vent area of > the hose cross section. You can look into the catch can and see how your > engine is doing. Nothing in the can? Doing just fine. Some oil in the catch > can? Watch engine closely. > > A couple of inches in the catch can? Put in the spare engine. > > The stock system of breathing into the intake manifold is fine for partial > throttle, freeway speeds where only 25 HP is being used. For constant wide > open throttle at about 6,000 RPM, and 160 HP, an adjustment must be made. > > Why do old Mazdas smoke and use oil? They drink it through the breather > hose connected to the intake manifold, as blow by increases with age. > Nothing to do the OMP (Oil Metering Pump) at all. > > The actual crank case pressure is a function of leak rate over vent tube > cross section. > > Lynn E. Hanover > > > --002215046ae31b53ac04909eb942 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Lynn,

Yes, that all makes perfect sense. =A0This is the = first time I really opened up the p-port 3-rotor. =A0So, it makes sense tha= t this is when the seal would fail. =A0I have a secondary vent that I plan = to install before next flight. =A0Thanks for sharing your knowledge of the = rotary with the group.=A0

Mark

On Sun, Sep 19, 2010 = at 10:09 AM, <Le= hanover@aol.com> wrote:
The engine and PSRU are a pressurized system at about the same pressur= e.=20 The engine is pressurized by blow by combustion gasses leaking past the sid= e=20 seals and oil scrapers. The PRSU is pressurized to the same value through t= he=20 oil drain-back line. So, drain back would be impeded to some extent until t= he=20 pressures are equal. After that it would be a constant until a power change= is=20 made that increases or decreases blow-by. Since the volume of the PSRU is s= o=20 small it could be discounted as a drain-back problem, but the same pressure= as=20 the crank case will still be present.=A0And that pressure added by the volu= me=20 of lubricating oil (at 70 PSI or more) for the bearings, though not a large= =20 factor when the drain back hose diameter is adequate.=A0
=A0
Some builders use the factory side seal end play specification, allowi= ng up=20 to .004". I use zero end play in side seals. I install them tight, and= then=20 reduce length until the side seals and corner seal will just pop back up af= ter=20 being fully compressed into the rotor. The side seal is being pushed along = by=20 only one side of the corner seal. The seal end wears into the corner seal i= n=20 short order. This starts making clearance right at break in. The direct out= come,=20 is nearly zero blow by. Pressure not lost to blow by, is free HP.
=A0
This does not apply to Renesis engines where the side seal is exposed = to=20 exhaust gas flow and needs extra clearance to survive. (Because it runs hot= ter=20 and gets longer).
=A0
Let us say that our engine has normal blow by of 12 cubic feet per min= ute.=20 The stock breather pipe in the filler tube is smaller than 3/16". This= means the=20 gas velocity out of that pipe and into a catch can may be very high. So ric= h in=20 energy that it can evacuate large amounts of oil droplets in the catch can.= So,=20 you make the vent pipe as large as is practical. That same 12 cubic feet, o= r=20 more,=A0still escapes, but now the crank case pressure is lower (less=20 restriction) and gas velocity is way down. Down on energy and velocity the= =20 escaping gasses can no long lift oil droplets and drop them into the catch = can.=20 The catch can must have at least 5 times the open vent area of the hose cro= ss=20 section. You can look into the catch can and see how your engine is doing.= =20 Nothing in the can? Doing just fine. Some oil in the catch can? Watch engin= e=20 closely.
=A0
A couple of inches in the catch can? Put in the spare engine.
=A0
The stock system of breathing into the intake manifold is fine for par= tial=20 throttle, freeway speeds where only 25 HP is being used. For constant wide = open=20 throttle at about 6,000 RPM, and 160 HP, an=A0adjustment must be made.
=A0
Why do old Mazdas smoke and use oil? They drink it through the breathe= r=20 hose connected to the intake manifold, as blow by increases with age. Nothi= ng to=20 do the OMP (Oil Metering Pump) at all.
=A0
The actual crank case pressure is a function of leak rate over vent tu= be=20 cross section.
=A0
Lynn E. Hanover
=A0
=A0

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