Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2) with ESMTP id 350719 for flyrotary@lancaironline.net; Tue, 03 Aug 2004 12:50:35 -0400 Received-SPF: none receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from EDWARD (cpe-069-132-183-211.carolina.rr.com [69.132.183.211]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i73Go2iB019627 for ; Tue, 3 Aug 2004 12:50:03 -0400 (EDT) Message-ID: <000801c47979$f0f1aaf0$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: May not work above 8000 MSL was [FlyRotary] Re: Oil injection, and more Date: Tue, 3 Aug 2004 12:50:10 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C47958.69A46180" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C47958.69A46180 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dave may be correct, Perry. Here is what I think could occur. First, The oil meter pump itself is = a positive displacement pump.=20 Therefore, from the standpoint of the pump it will always disperse any = oil fed to it into the injectors and combustion chamber under some = amount of pressure. However, the shaft opening that drives the pump = also provides for the oil flow from inside the Engine Front mount into = the metering pump. There is a hole in the boss of the metering pump = shaft (on the inside of the front housing) that is open to the = atmosphere. At sea level of course this hole in the boss results in 14.7 psi of = pressure on the oil in the meter shaft. So as the positive displacement = pump opens a chamber - the oil flows into the chamber with the help of = this 14.7 (or what ever the differential between the pressure in the = pump chamber and the atmosphere- it will something less than 14.7 but = probably greater than 12?) and gets "squirted" toward the injectors = underpressure. Of course, as altitude increases, there is less and less air pressure to = force the oil into the meter pump chamber. We know that the rate of oil = (or any liquid) flow is directly dependent on the pressure differential = between the high pressure side (atmospheric) and the low-pressure side = (pump chamber). So as atmospheric pressure decreases (all else staying = the same - like metering position) the oil flow into the pump and hence = into the combustion chamber undoubtedly drops off. At some point it may = be insufficient to provide the specified oil flow to the pump and = combustion chamber. Not saying there is none - just not as much as at = sea level. I suppose its also possible that as atmospheric pressure drops down to = say 8 psi at altitude, it may be insufficient to overcome the viscosity = of the oil and push it into the metering pump chamber - or at least not = at the normal flow of oil rate. The only thing that forces oil into the oil metering chamber is = atmospheric pressure. So as that decreases, I would suppose it possible = it might reach a point, at some altitude, that the pressure is not = adequate to move sufficient oil into the metering pump and therefore = into the combustion chamber.=20 At least that looks possible to me. FWIW Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC ----- Original Message -----=20 From: Perry Mick=20 To: Rotary motors in aircraft=20 Sent: Tuesday, August 03, 2004 9:00 AM Subject: [FlyRotary] Re: Oil injection, and more Al Gietzen wrote: It is my understanding (from David Atkins) is that the spring on the = metering pump forces the control to 'Low' position. Since this is a = critcal issue if relying upon the metered system for seal lubrication I = (we) would be forever grateful if someone would verify which way is = which. On a related subject, a posting on the ACRE list follows: Dave Atkins claims the apex seal oil metering system does not work = over=20 8000 feet. He also claims the engine will run up to three months in = automotive service with no apex seal oil whatsoever. We have some = verification of that as George Graham flew his airplane from Tennessee = to New York state while forgetting to mix two cycle oil with the fuel. If it be true, then that also is a bit of a critical piece of = information. But 'why'? The driving force for the metering system oil = flow (as best I can figure out) is the pressure differential between the = ambient atmospheric and the pressure in the combustion chamber during = the intake cycle. This would suggest that for a NA engine there would = always be some pressure to drive the flow.=20 And it is consistent that the metering control lever should be at = lowest flow for closed throttle position (greatest pressure = differential), and highest flow position for open throttle position = (lowest pressure differential). I'd guess there is the presumption that = the lubrication requirement is only a function of RPM, and not power = output, and the metering control level is for compensation of the = changes in pressure differential. Al Al, I just went out and checked it on my RX-7, and I was wrong. The = spring forces the pump to the minimum flow. Sorry for the erroneous = statement earlier. Like I said in a previous message, I premix 2-stroke = with the fuel, and just leave the minimal metering pump flow as a = backup, and it puts the oil right on the apex seal, which surely is more = effective than relying only on just the dispersed two-stroke oil. The = idea of running ONLY with premix has always made me a little nervous so = I wasn't willing to remove the stock system completely. Even with it set = to minimal flow you can see the oil moving in the tubes. For my first 200 hours I flew with the stock system and did not add = oil to the gas. I don't think I buy that statement that the metering pump quits = working above 8000'. Perry ------=_NextPart_000_0005_01C47958.69A46180 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dave may be correct, = Perry.
 
Here is what I think could occur.  = First, The=20 oil  meter pump itself is a positive displacement pump. =
 
Therefore, from the standpoint of the = pump it will=20 always disperse any oil fed to it into the injectors and combustion = chamber=20 under some amount of pressure.  However, the shaft opening that = drives the=20 pump also provides for the oil flow from inside the Engine Front = mount into=20 the metering pump.  There is a hole in the boss of the metering = pump shaft=20 (on the inside of the front housing) that is open to the=20 atmosphere.
 
  At sea level of course this hole = in the boss=20 results in 14.7 psi of pressure on the oil in the meter shaft.  So = as the=20 positive displacement pump opens a chamber  - the oil flows into = the=20 chamber with the help of this 14.7 (or what ever the differential = between the=20 pressure in the pump chamber and the atmosphere- it will something less = than=20 14.7 but probably greater than 12?)  and gets "squirted" toward the = injectors underpressure.
 
Of course, as altitude increases, there = is less and=20 less air pressure to force the oil into the meter pump chamber.  We = know=20 that the rate of oil (or any liquid) flow is directly dependent on the = pressure=20 differential between the high pressure side (atmospheric) and the = low-pressure=20 side (pump chamber).  So as atmospheric pressure decreases (all = else=20 staying the same - like metering position) the oil flow into the pump = and hence=20 into the combustion chamber undoubtedly drops off.  At some point = it may be=20 insufficient to provide the specified oil flow to the pump and = combustion=20 chamber. Not saying there is none - just not as much as at sea=20 level.
 
I suppose its also possible = that as=20  atmospheric pressure drops down to say 8 psi at altitude, it may = be =20 insufficient to overcome the viscosity of the oil and push it into the = metering=20 pump chamber - or at least not at the normal flow of oil = rate.
 
  The only thing that forces oil = into the oil=20 metering chamber is atmospheric pressure.  So as that decreases, I = would=20 suppose it possible it might reach a point, at some altitude, that the = pressure=20 is not adequate to move sufficient oil into the metering pump and = therefore=20 into the combustion chamber. 
 
At least that looks possible to = me. =20 FWIW
 
Ed
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From:=20 Perry = Mick=20
Sent: Tuesday, August 03, 2004 = 9:00=20 AM
Subject: [FlyRotary] Re: Oil = injection,=20 and more

Al Gietzen wrote:

 

It is my = understanding (from=20 David Atkins) is that the spring on the metering pump forces the = control to=20 =91Low=92 position.  Since this is a critcal issue if relying = upon the=20 metered system for seal lubrication I (we) would be forever grateful = if=20 someone would verify which way is which.

 

On a = related=20 subject, a posting on the ACRE=20 list follows:

Dave Atkins claims = the apex=20 seal oil metering system does not work over

8000 feet. He also = claims the=20 engine will run up to three months in automotive service with no = apex seal=20 oil whatsoever. We have some verification of that as George Graham = flew his=20 airplane from Tennessee to=20 New = York state=20 while forgetting to mix two cycle oil with the = fuel.

 

If it = be true,=20 then that also is a bit of a critical piece of information.  = But =91why=92?=20 The driving force for the metering system oil flow (as best I can = figure=20 out) is the pressure differential between the ambient atmospheric = and the=20 pressure in the combustion chamber during the intake cycle. =  This would=20 suggest that for a NA engine there would always be some pressure to = drive=20 the flow.

 

 And it is=20 consistent that the metering control lever should be at lowest flow = for=20 closed throttle position (greatest pressure differential), and = highest flow=20 position for open throttle position (lowest pressure = differential). =20 I=92d guess there is the presumption that the lubrication = requirement is only=20 a function of RPM, and not power output, and the metering control = level is=20 for compensation of the changes in pressure = differential.

 

Al

Al,=20 I just went out and checked it on my RX-7, and I was wrong. The spring = forces=20 the pump to the minimum flow. Sorry for the erroneous statement = earlier. Like=20 I said in a previous message, I premix 2-stroke with the fuel, and = just leave=20 the minimal metering pump flow as a backup, and it puts the oil right = on the=20 apex seal, which surely is more effective than relying only on just = the=20 dispersed two-stroke oil. The idea of running ONLY with premix has = always made=20 me a little nervous so I wasn't willing to remove the stock system = completely.=20 Even with it set to minimal flow you can see the oil moving in the=20 tubes.
For my first 200 hours I flew with the stock system and did = not add=20 oil to the gas.
I don't think I buy that statement that the = metering pump=20 quits working above = 8000'.

Perry

------=_NextPart_000_0005_01C47958.69A46180--