X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.122] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4493737 for flyrotary@lancaironline.net; Tue, 05 Oct 2010 09:57:59 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.122; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=Pa7Yp5IGPw0isBXBq+gaGcKMGLELYDnV27WxD07AD1I= c=1 sm=0 a=WBndAYlVUgsA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=3oc9M9_CAAAA:8 a=oEFHStp042e8dWnfbisA:9 a=I8aY1m4SgR0wZZisSAbJUYdQol4A:4 a=wPNLvfGTeEIA:10 a=U8Ie8EnqySEA:10 a=JCrxP-8a0y1vrJf1:21 a=PJXVArOQKXlf6cAa:21 a=Ia-xEzejAAAA:8 a=onfW2iyWQ43d7n5slQwA:9 a=-hlhhFDyxH0MLdJSJWQA:7 a=BYhy8eAj0rP2UXUHYUIlkHt5h_8A:4 a=EzXvWhQp4_cA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:49832] helo=EdPC) by cdptpa-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 4F/9E-19863-EBE2BAC4; Tue, 05 Oct 2010 13:57:18 +0000 Message-ID: <3AD8CCC7B12F4D47842D354D1E76F661@EdPC> From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Sam Hodges Prop area comparison Date: Tue, 5 Oct 2010 09:57:16 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_003B_01CB6473.B0F9F920" 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_003B_01CB6473.B0F9F920 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Doug, A three bladed prop would certainly remove any questions about = sufficient ground clearance. I flew with a 76 " prop on my RV-6A for about 1 year and you are correct = it does not leave but approx 4-5" in my case between tip and ground. = Taking one inch off makes it 6. I have been in and out of many grass strips, but always make it a soft = field landing keeping the hose gear out of gopher holes as long a = possible. Flying off of hard surface didn't present any problem I once (and that's more than enough) dropped it in from approx 14-16 = feet one time right after installing the new prop 76x88 - hard enough to = bend the main gear and drag the tail on the bounce (Did I mention I had = the stick sucked to my backbone) -- a direct result of failing to go up = to altitude with my new 76 " prop and do stall testing and low speed = flight with various power variations. It turns out, that having only previously flown with a 68x72 with my = 2.17:1 gear box, I was totally unprepared for the airbrake action of the = much larger prop when I pulled it completely back lower than 2200 engine = rpm. I must have lost 20 mph in about 2-3 seconds and way too high = before touch down. Due to the much higher "roll" forces with the larger = prop I had encountered on take off, I hesitated to apply full emergency = power - worried about it rolling the aircraft that near stall speed - = until the matter was taken out of my hands. I suspect I took the correct action (stick full back) not due to any = savy piloting skills, but because I had my brand new $1500 prop on the = nose {:>) I later replaced the gear and both had been bent by the impact and = replaced the rudder eyebolts where the impact of the bottom of the = rudder with the runway caused the bearing races to jam - but the prop = was undamaged. It was cheaper to replace the main gear than it would = have been to replace the prop, but not by much. Perhaps needless to say (but, I will) , when you put a new prop on your = bird - go up to altitude and make certain you know what it does near = stall speed. Ed From: DLOMHEIM@aol.com=20 Sent: Monday, October 04, 2010 11:57 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Sam Hodges Prop area comparison Ed Wrote: "When He put my 74x88 Performance Prop on he got as high as 6100 rpm one = time but each time got at least 6000 rpm...". Sam's prop actually measured 76 inches long (if I remember right) which = is quite a bit longer than I would want to run on a nose gear equipped = RV. A 76" prop leaves very little clearance off the ground and will = undoubtedly result in a considerable amount of blade tip erosion over = time. =20 If my IVO prop doesn't really work out I think I will give the CATO 3 = blade version a try since there are quite a few RVers flying it and it = will get the tips off the ground a bit more...at a cost of a couple = knots of top end of course! Doug Lomheim RV-9A, FWF / Canopy=20 OK City ------=_NextPart_000_003B_01CB6473.B0F9F920 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Doug,
 
A three bladed prop would certainly remove any = questions about=20 sufficient ground clearance.
 
I flew with a 76 " prop on my RV-6A for about 1 year = and you=20 are correct it does not leave but approx 4-5" in my case between tip and = ground.  Taking one inch off makes it 6.
 
  I have been in and out of many grass strips, = but always=20 make it a soft field landing keeping the hose gear out of gopher holes = as long a=20 possible.  Flying off of hard surface didn't present any=20 problem
 
 I once (and that's more than enough) dropped = it in from=20 approx  14-16  feet one time right after installing the new = prop 76x88=20 - hard enough to bend the main gear and drag the tail on the bounce (Did = I=20 mention I had the stick sucked to my  backbone) -- a direct result = of=20 failing to go up to altitude with my new 76 " prop and do stall testing = and low=20 speed flight with various power variations.
 
It turns out,  that having only = previously flown=20 with a 68x72 with my 2.17:1 gear box, I was totally unprepared for the = airbrake=20 action of the much larger prop when I pulled it completely back lower = than 2200=20 engine rpm.  I must have lost 20 mph in about 2-3 seconds and way = too high=20 before touch down.  Due to the much higher "roll" forces with the = larger=20 prop I had encountered on take off, I hesitated to apply full emergency = power -=20 worried about it rolling the aircraft that near stall speed - until the = matter=20 was taken out of my hands.
 
I suspect I took the correct action (stick full = back) not due=20 to any savy piloting skills, but because I had my brand new $1500 prop = on the=20 nose {:>)
 
I later replaced the gear and both had been bent by = the impact=20 and replaced the rudder eyebolts where the impact of the bottom of the = rudder=20 with the runway caused the bearing races to jam - but the prop was=20 undamaged.  It was cheaper to replace the main gear than it would = have been=20 to replace the prop, but not by much.
 
Perhaps needless to say (but, I will) , when you put = a new=20 prop on your bird - go up to altitude and make certain you know what it = does=20 near stall speed.
 
Ed

Sent: Monday, October 04, 2010 11:57 PM
Subject: [FlyRotary] Sam Hodges Prop area=20 comparison

Ed Wrote:
 
"When He put my 74x88 Performance Prop on he got as high as = 6100 rpm=20 one time but each time got at least 6000 rpm...".
 
Sam's prop actually measured 76 inches long (if I remember = right)=20 which is quite a bit longer than I would want to run on a nose gear = equipped=20 RV.  A 76" prop leaves very little clearance = off the=20 ground and will undoubtedly result in a considerable amount of = blade tip erosion over time.  
 
If my IVO prop doesn't really work out I think I will give=20 the CATO 3 blade version a try since there are quite a = few RVers=20 flying it and it will get the tips off the ground a bit more...at a = cost of=20 a couple knots of top end of course!
 
Doug Lomheim
RV-9A, FWF / Canopy
OK City  
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