X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 872241 for flyrotary@lancaironline.net; Mon, 12 Dec 2005 08:04:27 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id jBCD3XWe016876 for ; Mon, 12 Dec 2005 08:03:33 -0500 (EST) Message-ID: <000901c5ff1c$754aca10$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: "P" factor? Re: Static Engine RPM Date: Mon, 12 Dec 2005 08:03:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C5FEF2.8C0E3810" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C5FEF2.8C0E3810 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable No question, that having the nose pointed counter to the way it should = be - does contribute to the force I'm having to counter on take off. = And yes, I shan't forget the take off behind Finn in his RV-3 and the = forceful roll occurring immediately after lift off (thought for a moment = I had control failure). =20 Well, perhaps Santa might bring it to you sooner - as he is a flier also = you know. Charlie who?? {:>) Ed A=20 ----- Original Message -----=20 From: jbker@juno.com=20 To: Rotary motors in aircraft=20 Sent: Sunday, December 11, 2005 10:12 PM Subject: [FlyRotary] Re: "P" factor? Re: Static Engine RPM =20 Ed, Charlie England is going to get us for posting new at top, = but seems like this post is going that direction so I didn't reverse the = flight pattern=20 I think you are correct on both counts that P factor is = actually the torque generated when the prop runs a non-zero angle of = attack and what you are feeling may be the swirl effect on the flying = surfaces. You have demo'd the swirl effect from a plane taking off in = front of you (remembering your harry T/O behind Finn there)But I do = think that when the thrust line does not line up with the CG of the = airplane there is also a steering effect right or left depending on the = angle of the engine mount and yours aggrevates the swirling force. Bernie, no prop to fly with til after Christmas Hi Georges,=20 The "P" direction factor only changed when I changed from = the 2.17 to the 2.85 (with the opposite propeller rotation) . The = shortening of the prop slight reduced the "P" factor but did not change = its direction. One thing I think I should mention. I used to think the = force was caused by the "P" factor, but after reading an article about = the effects of Torque, "P" factor and Airstream whirl, I came away with = a different understanding. Apparently "P" factor is a factor primarily = with tail draggers as it is caused by the effect of the relative wind = and the prop blades not being perpendicular to the relative wind (until = the tail comes up). With a nose gear, the blades are perpendicular (at = least until lift off) and therefore the "P" factor is minimal. Apparently the real cause of the rather powerful force = that wants to push the nose to the left or right is the swirling air = caused by the spinning prop. Think of a cork screw. With my prop now = spinning CCW (from pilot's perspective) the corkscrew of air is swirling = CCW as well. It appears the distance from prop to vertical stabilizer = is such that the air corkscrews around so that more of it hits the left = side of the fuselage and vertical stab than the right. This air forces = the tail toward the right and the nose to the left, thereby requiring = right rudder to counteract the force. Sounded reasonable to me. Not to say there is not torque = or "P" factor but given the magnitude of the turning force I would say = the air swirl probably is the major factor. Ed A Ed A ----- Original Message -----=20 From: Echo Lake Fishing Resort (Georges Boucher)=20 To: Rotary motors in aircraft=20 Sent: Sunday, December 11, 2005 8:53 PM Subject: [FlyRotary] Re: Static Engine RPM Hi! Ed I guess I missed something, how can the P-factor = be in the"opposite" direction after shortening the prop 2"? Georges B.=20 -------Original Message------- From: Ed Anderson Date: 12/10/05 14:54:00 To: Rotary motors in aircraft Subject: [FlyRotary] Re: Static Engine RPM Hi Bernie, Good point, Yes, you are correct the engine mount = is still the same. However, since it only causes 1/2 ball deflection in = cruise, I not certain that the mount is that far offset in the wrong = direction. Guess I should add a few washers and find out - just = kidding. One of my numerous projects is to fabricate some new engine = mounting brackets (keeping the same mounting frame) with the offset to = the opposite side. =20 Besides, its really the increased ROC that really = tells the story. I consistently get over 1500 fpm and even get up into = the 1700 fpm range on cold days lightly loaded. Previously it was in = the 1000-1200 fpm range. Ok on the prop, Bernie. =20 I'm planning at this time to fly out to Bill = Eslick flyin in Feb weather permitting - make a nice long flight for = your 9. Ed A = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Hi Ed, Don't forget to add that the P-factor is now in = the opposite direction and I believe you did not change angle of engine = mount to offset this. I'm not questioning that you get more thrust with = this set up, just questioning if your criteria of lack of rudder is a = good indicator. Took your prop and the sensenich to plant city and = left both with them. Will probably be able to pick them up on the way = home from Memphis after Christmas. Cheers and Merry Christmas in NC, Bernie =20 =20 =20 ------=_NextPart_000_0006_01C5FEF2.8C0E3810 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
No question, that having the nose pointed = counter to the=20 way it should be - does contribute to the force I'm having to = counter on=20 take off.  And yes, I shan't forget the take off behind Finn = in his=20 RV-3 and the forceful roll occurring immediately after lift = off=20 (thought for a moment I had control failure). 
 
Well, perhaps Santa might bring it to you sooner = - as he=20 is a flier also you know.
 
Charlie who?? {:>)
 
Ed A 
 
----- Original Message -----
From:=20 jbker@juno.com
Sent: Sunday, December 11, 2005 = 10:12=20 PM
Subject: [FlyRotary] Re: "P" = factor? Re:=20 Static Engine RPM

 

Ed, Charlie England is going to get us for posting = new at=20 top, but seems like this post is going that direction so I = didn't=20 reverse the flight pattern
 
I think you are correct on both counts that P factor = is=20 actually the torque generated when the prop runs a = non-zero angle=20 of attack and what you are feeling may be the swirl effect = on the=20 flying surfaces. You have demo'd the swirl effect from a = plane=20 taking off in front of you (remembering your =  harry T/O=20 behind Finn there)But I do think that when the thrust line = does=20 not line up with the CG of the airplane there is also a = steering=20 effect right or left depending on the angle of the engine = mount=20 and yours aggrevates the swirling force.
 
Bernie, no prop to fly with til after Christmas
 
Hi Georges,
 
The "P" direction  factor only changed when I = changed=20 from the 2.17 to the 2.85 (with the opposite propeller = rotation)=20 .  The shortening of the prop slight reduced the "P" = factor=20 but did not change its direction.
 
One thing I think I should mention.  I used to = think the=20 force was caused by the "P" factor, but after reading an = article=20 about the effects of Torque, "P" factor and Airstream = whirl, I=20 came away with a different understanding.  Apparently = "P"=20 factor is a factor primarily with tail draggers as it is = caused by=20 the effect of the  relative wind and the prop = blades =20 not being perpendicular to the relative wind (until the = tail comes=20 up).  With a nose gear, the blades are perpendicular = (at=20 least until lift off) and therefore the "P" factor is=20 minimal.
 
Apparently the real cause of the rather powerful = force that=20 wants to push the nose to the left or right is = the swirling=20 air caused by the spinning prop.  Think of a cork=20 screw.   With my prop now spinning CCW (from = pilot's=20 perspective) the corkscrew of air is swirling CCW as = well. =20 It appears the distance from prop to vertical stabilizer = is such=20 that the air corkscrews around so that more of it hits the = left=20 side of the fuselage and vertical stab than the = right.  This=20 air forces the tail toward the right and the nose to the = left,=20 thereby requiring right rudder to counteract the = force.
 
Sounded reasonable to me.  Not to say there is = not=20 torque or "P" factor but given the magnitude of the = turning force=20 I would say the air swirl probably is the major = factor.
 
Ed A
 
 
 
Ed A
----- Original Message = -----=20
From:=20 Echo Lake Fishing Resort (Georges=20 Boucher)
To: Rotary motors in aircraft =
Sent: Sunday, = December 11,=20 2005 8:53 PM
Subject: = [FlyRotary] Re:=20 Static Engine RPM

Hi! Ed
I guess I missed something, how can the = P-factor be=20 in the"opposite" direction after shortening the = prop=20 2"?
Georges B. 
 
-------Original=20 Message-------
 
From:=20 Ed Anderson
Date:=20 12/10/05 14:54:00
To: Rotary motors in = aircraft
Subject: = [FlyRotary]=20 Re: Static Engine RPM
 
 Hi = Bernie,
 
Good point, Yes, you are = correct the=20 engine mount is still the same.  However, = since it=20 only causes 1/2 ball deflection in cruise, I not = certain=20 that the mount is that far offset in the wrong=20 direction.  Guess I should add a few washers = and find=20 out - just kidding.  One of my numerous = projects is=20 to fabricate some new engine mounting brackets = (keeping=20 the same mounting frame) with the offset to the = opposite=20 side. 
 
Besides, its really the = increased=20 ROC that really tells the story.  I = consistently get=20 over 1500 fpm and even get up into the 1700 fpm = range on=20 cold days lightly loaded.  Previously it was = in the=20 1000-1200 fpm range.
 
Ok on the prop, = Bernie. =20
 
I'm planning at this time = to fly out=20 to Bill Eslick flyin in Feb weather permitting - = make a=20 nice long flight for your 9.
 
Ed A
 
 
=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Hi Ed,
 
Don't forget to add that the P-factor is now = in the=20 opposite direction and I believe you did not = change angle=20 of engine mount to offset this. I'm not = questioning that=20 you get more thrust with this set up, just=20 questioning if your criteria of lack of rudder = is a=20 good indicator.
 
Took your prop and the sensenich to plant = city and=20 left both with them. Will probably be able to pick = them up=20 on the way home from Memphis after = Christmas.
 
Cheers and Merry Christmas in NC,
Bernie
=
 

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