X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ob0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTPS id 5597911 for flyrotary@lancaironline.net; Wed, 13 Jun 2012 15:43:32 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=keltro@gmail.com Received: by obbun3 with SMTP id un3so1157982obb.25 for ; Wed, 13 Jun 2012 12:42:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=WUhJ4kqxHB6vg1Itp5FQkeeKA7S2mWnPDSTvshWkSH8=; b=PglL1AcXPfaXo9XBFlwDL00vV4vXGHp2DzmuffaebPSEsZPRq9JBErgY2NalmeEr2V hPH8gg2xHsCdAAhPNfw40FjmZsiZu+fn9bpsSp2iOmc8P6G3SQLeDAZ6srMJDKmha68Z FLLfEoMx5KVOae03oTP4UN1raY0IWAZQTpP6H4b37isr6MwvOx/Oq3KIsNYAtXPQ7SBr 8/b7JEkU6gwtNuWGRqA2WssGKW8j0Q5m8mclUjG3iq0NwF5X1nxPeCs2lyE6iB/KfWtn JQqSjcF6W5jADPBbEQRxpp6ulVGXto7nqwgi9GaUKjGHwHS77JCGFcrvnaSV68Ael9JD FupQ== MIME-Version: 1.0 Received: by 10.182.111.39 with SMTP id if7mr18255709obb.55.1339616575441; Wed, 13 Jun 2012 12:42:55 -0700 (PDT) Received: by 10.60.28.70 with HTTP; Wed, 13 Jun 2012 12:42:55 -0700 (PDT) In-Reply-To: References: Date: Wed, 13 Jun 2012 14:42:55 -0500 Message-ID: Subject: Re: [FlyRotary] Re: IVO Prop Users... From: Kelly Troyer To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=14dae93990871d49f204c25fca7b --14dae93990871d49f204c25fca7b Content-Type: text/plain; charset=ISO-8859-1 Rich, I agree on your assessment on the use of the prop to control rpm.............The ammeter is merely a tool to avoid poping the IVO adjust motor elect breaker when reaching both the fine or coarse pitch limit stops and with enough use the pilot can learn to approx where the prop is pitched to.............Several of our group flying behind or ahead of the IVO use an ammeter for this purpose.............. Kelly Troyer On Wed, Jun 13, 2012 at 1:40 PM, wrote: > ** > I find this interesting, but confusing. > > While the amperage draw, of the prop) will give some indication of prop > blade pitch due to the fact that as the pitch changes, either positive or > negative from "neutral" and thus increases the current draw, Other than > giving one some sort of number to return to, for whatever reason, it does > not directly relate to the power that the engine is producing. > > The important information, with a variable or C/S prop is not the angle of > the blade, but, only, the combination of MP and RPM. > > Using these two indications, one can either calculate power, or > set consistent power values. So much more accurate to climb at 24"mp and > 2400 RPM (hypothetical value for example only), or whatever than to set a > pitch and hunt around for some obscure MP, to give you a desired RPM, never > really knowing what the engine is actually producing. > > If you look at a C/S prop, the blade angle/pitch of the prop is constantly > changing dependant on the load the propeller is experiencing in the various > phases of flight and the MP that is given to the engine. > > The paddle blades that he referenced are produced for airboats, not > aircraft. Probably the main reason that he found them unable to absorb the > power was that they were considerably under pitched with respect to the > original Magnum blades.--30-90 inch for the paddle vs 45-105 inch for the > magnum. > > Additionally the fact that -----"Static rpm at 39 inches was 4750 at 6 > amps fine however as soon as speed increased, rpm shot up to 5250 at only > 80 knots"---- was probably due to the phenomenon that his blades were > initially partially stalled at static and as the aircraft moved forward and > the angle of attack of the blades changed, they became unstalled. > > > A further point of confusion is the following statement--" I kept > retarding MAP to 25 inches in the climb to hold engine rpm under 5000 and I > finally had to increase prop pitch to neutral to stabilize the rpm. > Needless to say, the climb peformance is not so good at 25 inches. > > It seems like he was trying to maintain a certain RPM, rather than a > certain power by controlling the MP, rather than using the pitch of the > prop and its power absorption/transmission capabilities. to control the > RPM This is akin to starting your car in first gear uphill, full throttle > and when your RPMs reach your limit, as the hill starts to level off, > reducing the throttle rather than shifting to a higher gear and, all the > time, wondering why your performance is steadily decreasing. > > His comment that he had to increase the pitch to neutral indicated that he > was initially climbing with the blades at a rather flat pitch (on a > relatively flat pitch adjustability prop to begin with) and would coarsen > no further even though the twist of the blade was only at 1/2 max pitch. > > My comments, are, by no means to be construed as criticism of Ross, and > what he did and published, nor to Dis the IVO--(I have one) rather my > intent was to shed some light on prop/engine control basics, as I know > them, (having 7 C/S aircraft with a total of 9 engines, in the past), and > possibly start a conversation that might increase the knowledge of handling > a C/S or controllable prop, for all of us------ including me.. > > I don't know Ross but would really appreciate his replying to this reply > (if he is on the list) > > Rich > > > In a message dated 6/12/2012 10:53:18 P.M. Central Daylight Time, > DLOMHEIM@aol.com writes: > > I would highly recommend that any of you running an IVO in-flight > adjustable prop to take a few minutes of your time and read Ross's write up > on his SDS site...some great information found at: > > http://www.sdsefi.com/rv13.htm > > One thing I found interesting for instance was his use of a dedicated AMP > meter on his IVO circuit which then allows him to set his pitch based > on the amount of amps he is pulling... > > Doug Lomheim > RV-9A, 13B / FWF > > --14dae93990871d49f204c25fca7b Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Rich,
=A0 I agree on your assessment on the use of the prop to control rpm..= ...........The ammeter is merely a tool to avoid
poping the IVO adjust motor elect=A0breaker when reaching both the fin= e or coarse pitch limit stops and with
enough use the pilot can learn to approx where the prop is pitched to.= ............Several of our group flying behind
or ahead of the IVO use an ammeter for this purpose..............
=A0
Kelly Troyer


=A0
On Wed, Jun 13, 2012 at 1:40 PM, <ARGOLDMAN@aol= .com> wrote:
I find this interesting, but confusing.
=A0
While the amperage draw, of the prop)=A0will give some indication of p= rop blade pitch due to the fact that as the pitch changes, either positive = or negative from "neutral" and thus increases the current draw, O= ther than giving one some sort of number to return to, for whatever reason,= it does not directly relate to the power that the engine is producing.
=A0
The important information, with a variable or C/S prop is not the angl= e of the blade, but, only, the combination=A0 of MP and RPM.
=A0
Using these two indications, one can either calculate power, or set=A0= consistent power values. So much more accurate to climb at 24"mp and 2= 400 RPM (hypothetical value for example only), or whatever than to set a pi= tch and hunt around for=A0some obscure=A0MP, to give you a desired RPM,=A0n= ever really knowing what the engine is actually producing.
=A0
If you look at a C/S prop, the blade angle/pitch of the prop is consta= ntly changing dependant on the load the propeller is experiencing in the va= rious phases of flight and the MP that is given to the engine.
=A0
The paddle blades that he referenced are produced for airboats, not ai= rcraft. Probably the main reason that he found them unable to absorb the po= wer was that they were considerably under pitched with respect to the origi= nal Magnum blades.--30-90 inch for the paddle vs 45-105 inch for the magnum= .
=A0
Additionally the fact that -----"Static rpm at 39 inches was 4750= at 6 amps fine however as soon as speed increased, rpm shot up to 5250 at = only 80 knots"---- was probably due to the phenomenon that his blades = were initially partially stalled at static and as the aircraft moved forwar= d and the angle of attack of the blades changed, they became unstalled.
=A0
=A0
A further point of confusion is the following statement--"=A0 I k= ept retarding MAP to 25 inches in the climb to hold engine rpm under 5000 a= nd I finally had to increase prop pitch to neutral to stabilize the rpm. Ne= edless to say, the climb peformance is not so good at 25 inches.
=A0
It seems like he was trying to maintain a certain RPM, rather than a c= ertain power=A0by controlling the MP, rather than using the pitch of the pr= op and its power absorption/transmission capabilities. to control the RPM= =A0This is akin to starting your car in first gear uphill, full throttle an= d when your RPMs reach your limit, as the hill starts to level off, =A0redu= cing the throttle rather than shifting to a higher gear and, all the time, = wondering why your performance is steadily decreasing.
=A0
His comment that he had to increase the pitch to neutral indicated tha= t he was initially climbing with the blades at a rather flat pitch (on a re= latively flat pitch adjustability prop to begin with) and would coarsen no = further even though the twist of the blade was only at 1/2 max pitch.
=A0
My comments, are, by no means to be construed as=A0criticism =A0of Ros= s, and what he did and published, nor to Dis the IVO--(I have one) rather m= y intent was to shed some light on prop/engine control basics, as I know th= em, (having 7 C/S aircraft with a total of 9=A0 engines, in the past), and = possibly start a conversation that might increase the knowledge of handling= a C/S or controllable prop, for all of us------ including me..
=A0
I don't know Ross but would really appreciate his replying to this= reply (if he is on the list)
=A0
Rich
=A0
=A0
In a message dated 6/12/2012 10:53:18 P.M. Central Daylight Time, DLOMHEIM@aol.com writ= es:
I would highly recommend that any of you running an=A0IVO in-flight ad= justable prop to take a few minutes of your time and read Ross's write = up on his SDS site...some great information found at:
=A0
=A0
One thing I found interesting for instance was his use of=A0a dedicate= d=A0AMP meter on his IVO circuit which then allows him to set his=A0pitch b= ased on=A0the amount of amps he is pulling...=A0
=A0
Doug Lomheim
RV-9A, 13B / FWF



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