X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp017.mail.yahoo.com ([216.136.174.114] verified) by logan.com (CommuniGate Pro SMTP 5.0.3) with SMTP id 871323 for flyrotary@lancaironline.net; Sun, 11 Dec 2005 08:35:26 -0500 Received-SPF: none receiver=logan.com; client-ip=216.136.174.114; envelope-from=prvt_pilot@yahoo.com Received: (qmail 62648 invoked from network); 11 Dec 2005 13:33:47 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Received:Reply-To:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:In-Reply-To:Importance; b=LR1nWDt5S2PKcF9vgunI1J+NuBH1t8EW27szpp/s3q117XuKq99ZY0sZec1pTeXwAtXZge1aXSMyFzfUvC28E/f6Q3h4GZrdLjnrfmVM5xNXWpgSzK1EDWDK9kxe7RXOjboPyNZtNUyr4O3MwjSdYYJYM5b2bkObTtg0XNzEYz4= ; Received: from unknown (HELO stevehome) (prvt?pilot@71.0.19.116 with login) by smtp017.mail.yahoo.com with SMTP; 11 Dec 2005 13:33:46 -0000 Reply-To: From: "Steve Brooks" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Prop stall? Date: Sun, 11 Dec 2005 08:38:24 -0500 Message-ID: <00d301c5fe58$292ba330$6400a8c0@workgroup.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00D4_01C5FE2E.40559B30" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook CWS, Build 9.0.6604 (9.0.2911.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 In-Reply-To: Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_00D4_01C5FE2E.40559B30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Todd, I've heard the exact same noise that you described on 2 occasions. When I heard it the first time, I also thought that I had a issue with the PSRU, because it felt and sounded like something slipping. Both times, mine occurred when powering up from idle to take off power. The second time it happened I glanced at the mixture, and it was bottomed out on the lean side. I think that the noise was caused by detonation cause by a very lean fuel mixture. I immediately reduced throttle, and then advanced throttle again with no problem. Since then, I've been trying to advance the throttle more slowly, hoping to avoid the problem. I think that it may be caused by the spooling of the turbo driving the mixture lean, or else the EC2 MAP table may have a borderline mixture somewhere. Not sure. Steve Brooks [Steve Brooks] -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Todd Bartrim Sent: Sunday, December 11, 2005 4:27 AM To: Rotary motors in aircraft Subject: [FlyRotary] Prop stall? Hi Ed; This talk of stalled props brings up another question. Last week when I was doing circuits, on one of the touch & goes, moments after I'd applied power, the engine suddenly revved up momentarily much the same way as when you hit a patch of ice while driving a vehicle with a heavy foot. This happened very fast so I wasn't able to check the RPM (sure wish I had a datalogger), but both my buddy & I heard/felt it. My first thought was the PSRU had slipped, but it had no accompanying mechanical noise (like broken gears) then second thought was prop stall. I held it on the ground a little longer without reducing power, but as we pulled through 90mph with no further indication of a problem ( I still had several thousand feet of runway ahead of me) I let her lift off and then went on to complete another dozen circuits with no further incidents. But afterwards we discussed it further and I recalled Dave's broken PSRU shaft, but if I recall his was a clean break without any sort of preceding slip. This just leaves a prop stall as the likely culprit, but I wouldn't expect that a prop would stall when at approx. 50mph. At the time my electronic prop governor was on auto and had been performing well and in any case the electric IVO prop is too slow to have gone full fine momentarily so I can almost discount this as being related. Any thoughts on whether this could have simply been a momentarily stalled prop? Todd Interestingly enough before I had the prop shortened, I was a Tracy Crooks and was doing a run up to get some exhaust sound readings. It was a cool morning and the engine was turning around 5800-6000. Tracy and I (as well as the sound meter) could hear the prop blade stalling and unstalling (apparently as the blade rotate different orientation with respect to the cowl and effect the airflow enough to cause it to stall and that point and then recover). You could hear a distinct "wop! wop! Wop!" sound as the prop stalled and unstalled. ------=_NextPart_000_00D4_01C5FE2E.40559B30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Todd,
I've=20 heard the exact same noise that you described on 2 occasions.  When = I heard=20 it the first time, I also thought that I had a issue with the PSRU, = because it=20 felt and sounded like something slipping.    Both times, mine = occurred=20 when powering up from idle to take off power.  The second time it = happened=20 I glanced at the mixture, and it was bottomed out on the lean = side.  I=20 think that the noise was caused by detonation cause by a very lean fuel=20 mixture.  I immediately reduced throttle, and then advanced = throttle again=20 with no problem.  Since then, I've been trying to advance the = throttle more=20 slowly, hoping to avoid the problem.  I think that it may be caused = by the=20 spooling of the turbo driving the mixture lean, or else the EC2 MAP = table may=20 have a borderline mixture somewhere.  Not sure.
 
Steve=20 Brooks

[Steve=20 Brooks] 
 
 -----Original=20 Message-----
From: Rotary motors in aircraft=20 [mailto:flyrotary@lancaironline.net]On Behalf Of Todd=20 Bartrim
Sent: Sunday, December 11, 2005 4:27 AM
To: = Rotary=20 motors in aircraft
Subject: [FlyRotary] Prop=20 stall?

Hi=20 Ed;
    This talk of stalled props brings up another = question.=20 Last week when I was doing circuits, on one of the touch & goes, = moments=20 after I'd applied power, the engine suddenly revved up momentarily = much the=20 same way as when you hit a patch of ice while driving a vehicle with a = heavy=20 foot. This happened very fast so I wasn't able to check the RPM (sure = wish I=20 had a datalogger), but both my buddy & I heard/felt it. My first = thought=20 was the PSRU had slipped, but it had no accompanying mechanical = noise=20 (like broken gears) then second thought was prop stall. I held it on = the=20 ground a little longer without reducing power, but as we pulled = through 90mph=20 with no further indication of a problem ( I still had several thousand = feet of=20 runway ahead of me) I let her lift off and then went on to complete = another=20 dozen circuits with no further incidents. But afterwards we discussed = it=20 further and I recalled Dave's broken PSRU shaft, but if I recall his = was a=20 clean break without any sort of preceding slip. This just leaves a = prop stall=20 as the likely culprit, but I wouldn't expect that a prop would stall = when at=20 approx. 50mph. At the time my electronic prop governor was on auto and = had=20 been performing well and in any case the electric IVO prop is too slow = to have=20 gone full fine momentarily so I can almost discount this as being=20 related.
    Any thoughts on whether this could have = simply been a=20 momentarily stalled prop?
Todd   
 
Interestingly enough before I had the prop = shortened,=20 I was a Tracy Crooks and was doing a run up to get some exhaust = sound=20 readings.  It was a cool morning and the engine was turning = around=20 5800-6000.  Tracy and I (as well as the sound meter) could hear = the=20 prop blade stalling and unstalling (apparently as the blade rotate = different=20 orientation with respect to the cowl and effect the airflow enough = to cause=20 it to stall and that point and then recover).  You could hear a = distinct "wop! wop! Wop!" sound as the  prop stalled and = unstalled.=20
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