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 5.3.8) with ESMTP id 4439976 for flyrotary@lancaironline.net; Sun, 22 Aug 2010 13:50:20 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=6D2Pu8r2emdFQiJHTdCWDyd9204yeE59uf6s58fiEDo= c=1 sm=0 a=TqAbpbzBA-cA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=Ia-xEzejAAAA:8 a=3oc9M9_CAAAA:8 a=pGLkceISAAAA:8 a=on22okXAAAAA:8 a=XYupXIbjYFJMR7MnLqkA:9 a=Bk_uQinpPAgyfxEIrmkA:7 a=UrqEx3ZV25gpkvf1vVElv_FE0XQA:4 a=wPNLvfGTeEIA:10 a=EzXvWhQp4_cA:10 a=U8Ie8EnqySEA:10 a=MSl-tDqOz04A:10 a=at0Q5_2dr5wA:10 a=pxNgZt-5PZidyfCC:21 a=cRxMZ2KM_d5yCm2T:21 a=pedpZTtsAAAA:8 a=Ufi99MbR4fICqjp1Zs8A:9 a=h8EqCM7fCP9uMD1czAwA:7 a=dKWByOgXP47iiFdg4DOPHmLXzvYA:4 a=eJojReuL3h0A:10 a=SCsPibX5fRYawLfr:21 a=bN6YH3RXPtvPIvwE:21 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:56490] helo=EdPC) by cdptpa-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 49/79-22676-733617C4; Sun, 22 Aug 2010 17:49:44 +0000 Message-ID: <356FAB43778744FF9A77D6B49013EE74@EdPC> From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Prop orientation with TDC Date: Sun, 22 Aug 2010 13:49:42 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0015_01CB4200.DF678DD0" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_0015_01CB4200.DF678DD0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Bill, having made 3 engine out landings, I can tell you that it depends = on your airspeed. In my case, with the both the 2.17 and 2.85 my prop = continued to windmill with the airspeed above 110 mph - however, that = was not my best glide speed. So when I slowed it down to 87 mph for = best glide, the prop in both cases was no longer windmilling - which was = good as that reduced drag. Regarding hand prop of the rotary - at least using Tracy Crooks EC - you = simply can't do it. The computer expects to see at least 2 revolutions = of the prop at or above 150 rpm (value last time I talked to Tracy about = it-it might be slightly lower limit now) before it will activate the = ignition. I just don't think you're going to able to spin it at that = rate for two prop revs by hand. Ed From: Bill Bradburry=20 Sent: Sunday, August 22, 2010 1:23 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Prop orientation with TDC Can some of you more "experienced" folks tell me..does the prop windmill = after the engine quits, or does it stop rotating?=20 =20 Bill B =20 -------------------------------------------------------------------------= ------- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On = Behalf Of Lehanover@aol.com Sent: Sunday, August 22, 2010 11:29 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Prop orientation with TDC =20 In a message dated 8/22/2010 10:28:20 A.M. Eastern Standard Time, = blake.lewis@gmail.com writes: On Sat, Aug 21, 2010 at 7:34 AM, Jeff Whaley = wrote: > What is the Rotaries best prop orientation at the prop flange = relative to TDC? > The Lycomings are typically entering the compression stroke at 11-10 = o'clock and 5-4 o'clock. > The 13B goes through 3 compression strokes per e-shaft revolution - = does this predicate a 3-bladed prop is the ideal match? > Jeff The orientation idea comes from the older 4 cylinder airplane engines = that had to be hand started. So the position of the blade made a = difference in that the person starting the engine needed a good body = position to start out. It was also a good idea, because in the event of = an engine stoppage, that very same position had the prop near = horizontal, and that kept a blade from digging in on landing.=20 =20 In the rotary powered craft, the engine will be at TDC twice per crank = shaft rotation (for a two rotor) so, 2 times the reduction ratio tells = you how many times it gets to TDC per propeller revolution. 3 times for = a 3 rotor, and 4 times for a 4 rotor.=20 =20 A 2 rotor with a 2.78:1 reduction unit will see TDC 2 X 2.78 =3D 5.56 or = about every 65 degrees of prop rotation. =20 =20 This suggests that hand propping might be more difficult because of the = mechanical disadvantage of the reduction unit, and should the engine = fire, the length of time available to remove your hand might be very = short, should the very next rotor face fire as well.=20 =20 Lynn E. Hanover=20 ------=_NextPart_000_0015_01CB4200.DF678DD0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Bill, having made 3 engine out landings, I can = tell you=20 that it depends on your airspeed.  In my case, with the both the = 2.17 and=20 2.85 my prop continued to windmill with the airspeed above 110 mph - = however,=20 that was not my best glide speed.  So when I slowed it down to 87 = mph for=20 best glide, the prop in both cases was no longer windmilling - which was = good as=20 that reduced drag.
 
Regarding hand prop of the rotary - at least = using Tracy=20 Crooks EC - you simply can't do it.  The computer expects to see at = least 2=20 revolutions of the prop at or above 150 rpm (value last time I talked to = Tracy=20 about it-it might be slightly lower limit now) before it will activate = the=20 ignition.  I just don't think you're going to able to spin it at = that rate=20 for two prop revs by hand.
 
Ed

Sent: Sunday, August 22, 2010 1:23 PM
Subject: [FlyRotary] Re: Prop orientation with = TDC

Can some of = you more=20 =93experienced=94 folks tell me..does the prop windmill after the engine = quits, or=20 does it stop rotating?

 

Bill=20 B

 

From:=20 Rotary motors in aircraft=20 [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Lehanover@aol.com
Sent: Sunday, August 22, 2010 = 11:29=20 AM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: Prop = orientation=20 with TDC

 

In a message = dated=20 8/22/2010 10:28:20 A.M. Eastern Standard Time, blake.lewis@gmail.com=20 writes:

On Sat, = Aug 21, 2010=20 at 7:34 AM, Jeff Whaley <jwhaley@datacast.com> wrote:
> = What is=20 the Rotaries best prop orientation at the prop flange relative to = TDC?
>=20 The Lycomings are typically entering the compression stroke at 11-10 = o'clock=20 and 5-4 o'clock.
> The 13B goes through 3 compression strokes = per=20 e-shaft revolution - does this predicate a 3-bladed prop is the ideal=20 match?
> Jeff

The = orientation idea=20 comes from the older 4 cylinder airplane engines that had to be hand = started. So=20 the position of the blade made a difference in that the person starting = the=20 engine needed a good body position to start out. It was also a good = idea,=20 because in the event of an engine stoppage, that very same position had = the prop=20 near horizontal, and that kept a blade from digging in on landing.=20

 

In the = rotary powered=20 craft, the engine will be at TDC twice per crank shaft rotation (for a = two=20 rotor) so, 2 times the reduction ratio tells you how many times it gets = to TDC=20 per propeller revolution. 3 times for a 3 rotor, and 4 times for a 4 = rotor.=20

 

A 2 rotor = with a=20 2.78:1 reduction unit will see TDC 2 X 2.78 =3D 5.56 or about every 65 = degrees of=20 prop rotation. 

 

This = suggests that=20 hand propping might be more difficult because of the mechanical = disadvantage of=20 the reduction unit, and should the engine fire, the length of time = available to=20 remove your hand might be very short, should the very next rotor face = fire as=20 well.

 

Lynn E.=20 Hanover 

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