X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.129.170.194] (HELO VIRCOM1.fcdata.private) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTP id 5600376 for flyrotary@lancaironline.net; Thu, 14 Jun 2012 17:25:21 -0400 Received-SPF: none receiver=logan.com; client-ip=64.129.170.194; envelope-from=cbarber@texasattorney.net Received: from FCD-MAIL05.FCDATA.PRIVATE (unverified [172.16.5.24]) by VIRCOM1.fcdata.private (Vircom SMTPRS 5.1.1024.13396) with ESMTP id for ; Thu, 14 Jun 2012 16:24:37 -0500 X-Modus-BlackList: 172.16.5.24=OK;cbarber@texasattorney.net=OK X-Modus-RBL: 172.16.5.24=Excluded X-Modus-Trusted: 172.16.5.24=NO X-Modus-Audit: FALSE;0;0;0 Received: from FCD-MAIL06.FCDATA.PRIVATE ([fe80::697f:d6aa:b87:78d8]) by FCD-MAIL05.FCDATA.PRIVATE ([fe80::809d:a06e:5913:452e%13]) with mapi id 14.01.0355.002; Thu, 14 Jun 2012 16:23:27 -0500 From: Chris Barber To: Rotary motors in aircraft CC: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: IVO Prop controls Thread-Topic: [FlyRotary] Re: IVO Prop controls Thread-Index: AQHNSkrFImEofB5JFEqC/O8yeYWrI5b6U6We Date: Thu, 14 Jun 2012 21:25:26 +0000 Message-ID: <6EDEF58A-7E11-448E-A70D-7E2A8BB6577A@texasattorney.net> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Type: multipart/alternative; boundary="_000_6EDEF58A7E11448EA70D7E2A8BB6577Atexasattorneynet_" MIME-Version: 1.0 --_000_6EDEF58A7E11448EA70D7E2A8BB6577Atexasattorneynet_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Gee Ed, if ya want a proof of concept bird, I am testing anyway :-) Chris Sent from my iPhone 4 On Jun 14, 2012, at 11:30 AM, "Ed Anderson" > wrote: Back a few years ago, there was a variable pitch prop hub designed by a gen= us of a mechanical engineer. It had a pitch control mechanism similar to t= he IVO adjustable pitch prop. I designed a control circuit which among oth= er things monitored the current draw of the pitch motor. While the prop project was not completed (to the best of my knowledge), I f= ound it was possible by conducting some test measurements to correlate the= current draw curve to propeller pitch. Now the missing part was - we nev= er got to the point of installing and running the prop using the controller= . Its highly likely that the current curve would be different under air lo= ads than not. We did not use a meter but instead had the current turn on a= n LED (red) when the limit was hit. One of the things that I had planned to do was incorporate a manifold press= ure input (as well as prop rpm) to automatically adjust to prop pitch to ma= intain rpm under various loading. The hardware to do so was completed and = the software - just never got tested. Just found some of the old code begin //Main RPM_Limit_Low :=3D 3000; RPM_Limit_High:=3D 7000; RPM_TO :=3D 5800; RPM_CC :=3D 5600; RPM_CR :=3D 5200; RPM_DC :=3D 5500; //Put address of varible RPM_TO into Pointer variable PORTB.RB0 :=3D 1; //set to enter while loop in procedure While testbit(INTCON,RBIF) =3D 0 do I now recall that we actually had several target settings such as TO (Take = off), CC (Cruise Climb), CR (Cruise Range), and others for various flight r= egimes. So you could choose TO, CC, CR or DC from a menu and the prop was = pitch was positioned/adjusted to maintain the rpm. Manifold pressure was a= lso a factor. Also it had direction LEDs so you could select to manuall/el= ectrically increase or decrease pitch and a bunch of other things I have no= w forgotten. You could adjust those rpm values that best suited your parti= cular aircraft/engine combination - the preset values were intended to redu= ce the pilot work load. I was programming a PIC 18F450 chip to handle the control and sensor inputs= and provide a user interface on an LCD display with buttons. It would have been great had the prop project gone on to completion, but al= as despite the best efforts of a number of good folks it did not. Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com From: Chad Robinson Sent: Wednesday, June 13, 2012 5:52 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: IVO Prop controls I think there's a miscommunication about how this device works. It's quite = simple: two commutator brushes on a fixed arm transfer current into the pro= p hub to engage the motor and twist the prop blades. Like most motors/actua= tors, you wire it such that positive voltage is applied to turn it one way,= negative turns it the other, and while not moving there is no voltage appl= ied. A simple (ON)-OFF-(ON) switch drives this. There are only two brushes so there's no way to transfer an at-limit signal= , and although I'm just guessing here, a reliable pair of limit switches th= at can operate properly inside the prop at full RPM would have been complic= ated/maybe unreliable? They'd also be a pain to adjust. Anyway, the motor draws only a moderate amount of current in the middle of = its travel, and this increases as you approach the limits. Standard practic= e is to install a meter to indicate this draw and it tells you when you're = near the limit. You could install a PTC instead of a breaker, but it's hardly an emergency.= It's not actually SOP to run it that far - in the times I've flown with Jo= hn I don't recall him ever doing it except perhaps once to show me what hap= pens. You don't "run it until it pops." You "run it until it's where you wa= nt it to be." So PTC or breaker, it doesn't really make that much of a diff= erence. Choose the safety device you prefer. I don't understand the bit about the shorted switch. That's pretty rare, an= d the breaker would deal with it just fine. And I can't speak for anybody e= lse, but every car I've ever owned doesn't use a PTC to set the travel limi= t on the window, it uses a limit switch on the actuator. I recall having to= adjust mine one time in a Subaru, just like the nose gear travel switches = in a Cozy. Besides, what's the down side here? You short your switch and the breaker w= ill deal with it, and the prop will stop twisting. No matter WHICH device y= ou use, in this case you now have no way to move the prop because a short w= ould hold a PTC open and also keep tripping a breaker when you manually res= et that. Both devices have the same failure mode if it's the switch that's = the problem. But you still have a working prop even if it's not at the opti= mal pitch. See if you can jiggle the switch to clear the short... To each his own. Regards, Chad On 6/13/12 5:15 PM, Lehanover@aol.com wrote: Why in the world would IVO use a device that is designed to fail critical f= light gear in the case of improper control manipulation when they don't have to? Isn't this the classical and proper a= pplication for a polyfuse? Polyfuses are used in power windows for this exact reason. You're kids can pull on that s= witch all day without damaging the window motor. I'm thinking of the case where a switch gets shorted (like my belt s= ander's switch is right now...the power cord is serving as a temp fix until I get time), or someone accidentally leans s= omething against the switch. Why does the motor draw current after the pitch has been changed? Lynn E. Hanover No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2180 / Virus Database: 2433/5068 - Release Date: 06/13/12 --_000_6EDEF58A7E11448EA70D7E2A8BB6577Atexasattorneynet_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
Gee Ed, if ya want a proof of concept bird, I am testing anyway :-)

Chris

Sent from my iPhone 4

On Jun 14, 2012, at 11:30 AM, "Ed Anderson" <eanderson@carolina.rr.com> wrote:

Back a few years ago, there was a variable pitch = prop hub designed by a genus of a mechanical engineer.  It had a pitch= control mechanism similar to the IVO adjustable pitch prop.  I design= ed a control circuit which among other things monitored the current draw of the pitch motor. 
 
While the prop project was not completed (to the = best of my knowledge), I found it was  possible by conducting som= e test measurements to correlate the current draw curve to propeller pitch.=   Now the missing part was -  we never got to the point of installing and running the prop using the controller.  I= ts highly likely that the current curve would be different under air loads = than not.  We did not use a meter but instead had the current turn on = an LED (red) when the limit was hit. 
 
One of the things that I had planned to do was in= corporate a manifold pressure input (as well as prop rpm) to automatically = adjust to prop pitch to maintain rpm under various loading.  The hardw= are to do so was completed and the software - just never got tested.
 
Just found some of the old code
 
begin  //Main
 
   RPM_Limit_Low :=3D 3000;
    RPM_Limit_High:=3D 7000;
 
    RPM_TO :=3D 5800;
    RPM_CC :=3D 5600;
    RPM_CR :=3D 5200;
    RPM_DC :=3D 5500;
    //Put address of varible RPM_TO into Pointer variable     PORTB.RB0 :=3D 1; //set to enter while loop in procedure=
While testbit(INTCON,RBIF) =3D 0 do
 
I now recall that we actually had several target = settings such as TO (Take off), CC (Cruise Climb), CR (Cruise Range), and o= thers for various flight regimes.  So you could choose TO, CC, CR or D= C from a menu and the prop was pitch was positioned/adjusted to maintain the rpm.  Manifold pressure was also = a factor.  Also it had direction LEDs so you could select to manuall/e= lectrically increase or decrease pitch and a bunch of other things I have n= ow forgotten.  You could adjust those rpm values that best suited your particular aircraft/engine combination - the = preset values were intended to reduce the pilot work load.
 
I was programming a PIC 18F450 chip to handle the= control and sensor inputs and provide a user interface on an LCD display w= ith buttons.
 
It would have been great had the prop project gon= e on to completion, but alas despite the best efforts of a number of good f= olks it did not.
 
Ed
 
Edward L. Anderson
Anderson Electronic Enterprises LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com
 
 
 
 

Sent: Wednesday, June 13, 2012 5:52 PM
Subject: [FlyRotary] Re: IVO Prop controls

I think there's a miscommunication about how this device works. It's quite = simple: two commutator brushes on a fixed arm transfer current into the pro= p hub to engage the motor and twist the prop blades. Like most motors/actua= tors, you wire it such that positive voltage is applied to turn it one way, negative turns it the other, and wh= ile not moving there is no voltage applied. A simple (ON)-OFF-(ON) switch d= rives this.

There are only two brushes so there's no way to transfer an at-limit signal= , and although I'm just guessing here, a reliable pair of limit switches th= at can operate properly inside the prop at full RPM would have been complic= ated/maybe unreliable? They'd also be a pain to adjust.

Anyway, the motor draws only a moderate amount of current in the middle of = its travel, and this increases as you approach the limits. Standard practic= e is to install a meter to indicate this draw and it tells you when you're = near the limit.

You could install a PTC instead of a breaker, but it's hardly an emergency.= It's not actually SOP to run it that far - in the times I've flown with Jo= hn I don't recall him ever doing it except perhaps once to show me what hap= pens. You don't "run it until it pops." You "run it until it's where you want it to be." So = PTC or breaker, it doesn't really make that much of a difference. Choose th= e safety device you prefer.

I don't understand the bit about the shorted switch. That's pretty rare, an= d the breaker would deal with it just fine. And I can't speak for anybody e= lse, but every car I've ever owned doesn't use a PTC to set the travel limi= t on the window, it uses a limit switch on the actuator. I recall having to adjust mine one time in a Subar= u, just like the nose gear travel switches in a Cozy.

Besides, what's the down side here? You short your switch and the breaker w= ill deal with it, and the prop will stop twisting. No matter WHICH device y= ou use, in this case you now have no way to move the prop because a short w= ould hold a PTC open and also keep tripping a breaker when you manually reset that. Both devices have the sam= e failure mode if it's the switch that's the problem. But you still have a = working prop even if it's not at the optimal pitch. See if you can jiggle t= he switch to clear the short...

To each his own.

Regards,
Chad

On 6/13/12 5:15 PM, Lehanover@aol.com wrote:
Why in the world would IVO use a device that is desig= ned to fail critical flight gear in the case of improper control
manipulation when they don't have to? Isn't this the classical and proper a= pplication for a polyfuse? Polyfuses are
used in power windows for this exact reason. You're kids can pull on that s= witch all day without damaging the window
motor. I'm thinking of the case where a switch gets shorted (like my belt s= ander's switch is right now...the power cord
is serving as a temp fix until I get time), or someone accidentally leans s= omething against the switch.
Why does the motor draw current after the pitch has been changed?
 
Lynn E. Hanover 

No virus found in this m= essage.
Checked by AVG - www.avg.com
Version: 2012.0.2180 / Virus Database: 2433/5068 - Release Date: 06/13/12

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