X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from m12.lax.untd.com ([64.136.30.75] verified) by logan.com (CommuniGate Pro SMTP 5.0.3) with SMTP id 871602 for flyrotary@lancaironline.net; Sun, 11 Dec 2005 14:52:41 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.136.30.75; envelope-from=alwick@juno.com Received: from m12.lax.untd.com (localhost [127.0.0.1]) by m12.lax.untd.com with SMTP id AABB33A4PAL286ES for (sender ); Sun, 11 Dec 2005 11:51:41 -0800 (PST) Received: (from alwick@juno.com) by m12.lax.untd.com (jqueuemail) id LBYC3EBL; Sun, 11 Dec 2005 11:50:43 PST To: flyrotary@lancaironline.net Date: Sun, 11 Dec 2005 11:33:45 -0800 Subject: Re: [FlyRotary] Prop stall? Message-ID: <20051211.115000.2668.4.alwick@juno.com> X-Mailer: Juno 5.0.33 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=--__JNP_000_72b7.22db.708d X-Juno-Line-Breaks: 8-6,9,12-21,23-24,43,45-47,55-61,62-32767 From: al p wick X-ContentStamp: 3:5:1167094263 X-MAIL-INFO:3205052951a0600180c0e929e5e9d91d9d64fde98414d0345184fd64842d8419e4b1cd7d0555296529415110d935741001a075b1c56dadd96040007125f06d11750da945a4112135 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkCMBtIjyP+2w8cHhAiTlpi1MhCI0G7HIag== X-UNTD-Peer-Info: 127.0.0.1|localhost|m12.lax.untd.com|alwick@juno.com This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ----__JNP_000_72b7.22db.708d Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Valuable lesson here. We will continue with departure even though we shouldn't. This is natural, as we are conditioning ourselves each time we fly to continue with the departure. Before you takeoff, pick 1/2 way marker next to runway. Plan on aborting before you reach that point. It's essential to abort takeoffs periodically just to train yourself to this alternative. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html On Sun, 11 Dec 2005 01:27:16 -0800 "Todd Bartrim" writes: 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. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ----__JNP_000_72b7.22db.708d Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: quoted-printable
Valuable lesson here. We will continue with departure even though we=20 shouldn't. This is natural, as we are conditioning ourselves each time we = fly to=20 continue with the departure.
Before you takeoff, pick 1/2 way marker next to runway. Plan on = aborting=20 before you reach that point. It's essential to abort takeoffs periodically = just=20 to train yourself to this alternative.
 

-al wick
Artificial intelligence in cockpit, Cozy IV powered by= =20 stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland,=20 Oregon
Prop construct, Subaru install, Risk assessment, Glass panel = design=20 info:
http:= //www.maddyhome.com/canardpages/pages/alwick/index.html
 
On Sun, 11 Dec 2005 01:27:16 -0800 "Todd Bartrim" <haywire@telus.net> writes:
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=20 distinct "wop! wop! Wop!" sound as the  prop stalled and unstalled= .=20
 

-al wick
Artificial intelligence in= =20 cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on=20 engine/airframe from Portland, Oregon
Prop construct, Subaru install, = Risk=20 assessment, Glass panel design=20 info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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