X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3897881 for flyrotary@lancaironline.net; Sat, 24 Oct 2009 09:16:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta04.mail.rr.com with ESMTP id <20091024131536575.BHRU17264@cdptpa-omta04.mail.rr.com> for ; Sat, 24 Oct 2009 13:15:36 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] RPM drop Date: Sat, 24 Oct 2009 09:15:41 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0020_01CA548A.8F0722B0" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcpUevI4E7/ipQwNS8WGTWIdX8BqRAAL8yjA X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 In-Reply-To: Message-Id: <20091024131536575.BHRU17264@cdptpa-omta04.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0020_01CA548A.8F0722B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Chris, as always, the internal combustion engine is a complex mix of processes. However, my engine can idle all day without temperature concerns - however, it only takes a minute or so at WOT and the temps are near their max. However, no problem when flying - so I wouldn't be too concerned about temps under those engine run temps at this point. Yes, you can put larger radiators/oil coolers and get more air flow and keep the temps lower on the ground, but then you are carrying all that "surplus" cooling around when you don't really need it (my personal opinion of course). There are two things that come to mind concerning your rpm drop (You do need to provide more data than rpm, manifold pressure, fuel pressure (where is it measured?), air/fuel ratio indication (does it go lean when the rpm drop off or not?), etc. 1st It COULD be a restriction in your fuel system - running up to 6000 rpm the first time - there is "surplus" fuel that permits you to get there - but a restriction could then preclude you from maintaining that rpm for more than a short time because a fuel restriction inhibits fuel flow. But, if this is the case then you should see your air/fuel ratio indicator start to show a lean mixture. 2nd A second possibility is that as the engine heats up you could be loosing compression and that results in a loss of some power and the rpm drop back down - however, the fact that you can then run the engine back up to (almost) 6000 rpm tends to indicate this is probably not your problem. I would suspect a fuel flow restriction myself - you can "zoom" up to 6000 rpm but then the restricted fuel flow causes engine to drop back to an rpm sustainable by the restricted flow. That's my $0.02 based on the information you have provide thus far. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris Barber Sent: Saturday, October 24, 2009 3:23 AM To: Rotary motors in aircraft Subject: [FlyRotary] RPM drop I hooked up my front oil cooler, the aviation one that was causing a restriction in the system and leakage past the oil filter seal, in parallel today with the standard Mazda stock radiator. I cranked her up and the oil flowed and heated all parts of the system and after only one snugging of a fixture, no leaks. Temps still were about the same. I took the engine to full power. It does not like full power on the ramp. The temps raise really quickly and even after 60 seconds, I am at limits I am uncomfortable with. I can have it sit at idle for over an hour with no problem. I have fans mounted, but they do not seem to help much at high RPM's. The weather was quite cool for Houston at about 70 degrees today. On a related note. As I have mentioned I am getting just over 6000 rpm at full throttle when I enrich the mixture. HOWEVER, once at full throttle the rpm is dropping off a few hundred rpm....maybe down to 5400 rpm. If I throttle back and go back to WOT it can get to just about 6000 again....maybe not quite 6000. I can't play with it too long like this as the temps raise so quickly. Is this something obvious that I can check? Thoughts???? Thanks again. All the best, Chris Barber Houston __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_0020_01CA548A.8F0722B0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Chris,  as always, the = internal combustion engine is a complex mix of processes.  However, my engine can idle = all day without temperature concerns – however, it only takes a minute or = so at WOT and the temps are near their max.  However, no problem when = flying – so I wouldn’t be too concerned about temps under those engine run = temps at this point.  Yes, you can put larger radiators/oil coolers and = get more air flow and keep the temps lower on the ground, but then you are carrying = all that “surplus” cooling around when you don’t really need it = (my personal opinion of course).

 

There are two things that come to = mind concerning your rpm drop (You do need to provide more data than rpm, = manifold pressure, fuel pressure (where is it measured?), air/fuel ratio = indication (does it go lean when the rpm drop off or not?), = etc.

 

1st  It COULD be a = restriction in your fuel system – running up to 6000 rpm the first time = – there is “surplus” fuel that permits you to get there – but = a restriction could then preclude you from maintaining that rpm for more = than a short time because a fuel restriction inhibits fuel flow.  But, if = this is the case then you should see your air/fuel ratio indicator start to show a = lean mixture. 

 

2nd  A second = possibility is that as the engine heats up you could be loosing compression and that = results in a loss of some power and the rpm drop back down – however, the = fact that you can then run the engine back up to (almost) 6000 rpm tends to = indicate this is probably not your problem.

 

I would suspect a fuel flow = restriction myself – you can “zoom” up to 6000 rpm but then the restricted fuel flow causes engine to drop back to an rpm sustainable by = the restricted flow.

 

That’s my $0.02 based on the information you have provide thus far.

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris Barber
Sent: Saturday, October = 24, 2009 3:23 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] RPM = drop

 

I hooked up my front oil cooler, the aviation one that was = causing a restriction in the system and leakage past the oil filter seal, in parallel today with the standard Mazda stock radiator.  I = cranked her up and the oil flowed and heated all parts of the system and after = only one snugging of a fixture, no leaks.  Temps still were about = the same.  I took the engine to full power.  It does not like full = power on the ramp.  The temps raise really quickly and even after 60 = seconds, I am at limits I am uncomfortable with.  I can have it sit = at idle for over an hour with no problem.  I have fans mounted, but they do = not seem to help much at high RPM's.  The weather was quite cool for = Houston at = about 70 degrees today.

 

On a related note.  As I have mentioned I am getting just = over 6000 rpm at full throttle when I enrich the mixture.  HOWEVER, once = at full throttle the rpm is dropping off a few hundred rpm....maybe down to = 5400 rpm.  If I throttle back and go back to WOT it can get to just = about 6000 again....maybe not quite 6000.  I can't play with it too long = like this as the temps raise so quickly.

 

Is this something obvious that I can check?  = Thoughts????

 

Thanks again.

 

All the best,

 

Chris Barber

Houston



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