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 5.0.7f) with ESMTP id 950384 for flyrotary@lancaironline.net; Mon, 23 Jan 2006 10:46:56 -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 (8.13.4/8.13.4) with SMTP id k0NFji4P016076 for ; Mon, 23 Jan 2006 10:45:46 -0500 (EST) Message-ID: <001501c62034$13a05260$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Prop controller RPM and Motor Limits was Re: Injector pulseing ? Tracy ? Date: Mon, 23 Jan 2006 10:45:46 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01C6200A.2A804910" 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_0012_01C6200A.2A804910 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageHi Thomas, There at two design considerations that need attention when designing a = controller for an electric pitch prop. One is determining prop rpm and = the second is to determine when the pitch motor has reached its limits = of travel. Prop RPM? When I decided to design an electric prop automatic pitch controller, I = ran into the same design considerations. You need engine/prop rpm from = some source. I decided to use an IR sensor reading a tape on the prop = (to read its rpm directly) since I did not know what rpm sources might = exist on different automobile engine conversions as well as different = gear ratios which would ,of course, affect relationship between engine = and prop speed. However, there are many ways to approach that need. I currently derive = RPM form my EFI Monitor from measuring the interval between injections = (once per e shaft rev). I suspect that Mark is taking a similar = approach to get rpm for his controller. My controller was designed to maintain a certain prop rpm by sensing the = prop rpm and automatically varying the pitch to maintain that rpm within = a small window (to prevent rpm hunting). So if Power was increased the = prop would automatically increase pitch to absorb the power and keep the = rpm within the window and vice versa when power was reduced. I also had three "pre-programmed" rpms for Take off, Climb and Cruise = that you could set by the push of a button. You could also manual = establish your target rpm. I had the design 90% completed when the prop project went away so never = finished it. Pitch Motor Limits? I think the second problem, as you mentioned, is determining the pitch = motor travel limits to which I do not believe rpm is a crucial factor. = You could install limit switches with the risk of added complexity and = weight or you can devise a method to determine and warn when the limits = are approached.=20 I used a current sensing circuit (which you could adjust for different = current levels) to light an LED. The more current the motor drew the = brighter the LED glowed. So when the motor approached its stall limit = and current increased dramatically over the running current, the LED = would start to glow and the further you ran the motor to the limit the = brighter it would glow. The operator must take the corrective action - = although I already had a design in the conceptual stage to reverse the = motor when the current exceeded a set amount. Then I decided that I did = not want some computer making that decision {:>) Hope this might clarify some of the discussion Ed ----- Original Message -----=20 From: rijakits=20 To: Rotary motors in aircraft=20 Sent: Monday, January 23, 2006 9:46 AM Subject: [FlyRotary] Re: Injector pulseing ? Tracy ? Question. Why does he ( Mark B.) need the injector pulses? Unless he wants to have an automatic-best-performance feature, a = simple rpm reading from the crank will do fine. a) Electronics will increase pitch when power is increased to maintain = rpm in C/S mode. b) Pilot will change pitch in a variable pitch mode. AFAIU the problem is to find the exact endpoints of pitch travel. How = does knowing the injector pulse width help with that? It will tell him how much power is produced in combination with an rpm = input, but does he also measure airspeed? Not bitching, just trying to get the idea!! Thomas J. From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Monday, January 23, 2006 8:55 AM Subject: [FlyRotary] Re: Injector pulseing ? Tracy ? And how would Mark Burton's constant speed controller react if the EC2 was switched to = injector disable mode. Depending on how it was wired, it might suddenly = sense zero power or 2X power. Just thinking out loud. Good point Dean. If he only senses pulses to one injector, then it = would have to be the primary, which is always active, unless you turn it = off via the disable switch. He may not realize we have the ability to = do that, so it would be worth telling him about it. =20 Cheers, Rusty=20 ------=_NextPart_000_0012_01C6200A.2A804910 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Hi Thomas,
 
There at two design considerations that need = attention=20 when designing a controller for an electric pitch prop.  One is = determining=20 prop rpm and the second is to determine when the pitch motor has reached = its=20 limits of travel.
 
Prop RPM?
 
When I decided to design an electric prop = automatic pitch=20 controller, I ran into the same design considerations.  You need=20 engine/prop rpm from some source.  I decided to use an IR sensor = reading a=20 tape on the prop (to read its rpm directly) since I did not know what = rpm=20 sources might exist on different automobile engine conversions as well = as=20 different gear ratios which would ,of course, affect relationship = between engine=20 and prop speed.
 
However, there are many ways to approach that = need. =20 I currently derive RPM form my EFI Monitor from measuring the interval = between=20 injections (once per e shaft rev).  I suspect that Mark is taking a = similar=20 approach to get rpm for his controller.
 
My controller was designed to maintain a certain = prop rpm=20 by sensing the prop rpm and automatically varying the pitch to maintain = that rpm=20 within a small window (to prevent rpm hunting).  So if Power was = increased=20 the prop would automatically increase pitch to absorb the power and keep = the rpm=20 within the window and vice versa when power was reduced.
 
I also had three "pre-programmed" rpms for Take = off, Climb=20 and Cruise that you could set by the push of a button.  You could = also=20 manual establish your target rpm.
 
I had the design 90% completed when the prop = project went=20 away so never finished it.
 
Pitch Motor Limits?
 
I think the second problem, as you mentioned, is = determining the pitch motor travel limits to which I do not believe rpm = is a=20 crucial factor.  You could install limit switches with the risk of = added=20 complexity  and weight or you can devise a method to determine and = warn=20 when the limits are approached. 
 
 I used a current sensing circuit (which = you could=20 adjust for different current levels) to light an LED.  The more = current the=20 motor drew  the brighter the LED glowed.  So when the motor = approached=20 its stall limit and current increased dramatically over the running = current, the=20 LED would start to glow and the further you ran the motor to the limit = the=20 brighter it would glow.  The operator must take the corrective = action -=20 although I already had a design in the conceptual stage to reverse the = motor=20 when the current exceeded a set amount.  Then I decided that I did = not want=20 some computer making that decision {:>)
 
Hope this might clarify some of the=20 discussion
 
 
Ed
----- Original Message -----
From:=20 rijakits
Sent: Monday, January 23, 2006 = 9:46=20 AM
Subject: [FlyRotary] Re: = Injector=20 pulseing ? Tracy ?

Question.
 
Why does he ( Mark B.) need the injector=20 pulses?
Unless he wants to have an = automatic-best-performance=20 feature, a simple rpm reading from the crank will do = fine.
a) Electronics will increase pitch when power = is=20 increased to maintain rpm in C/S mode.
b) Pilot will change pitch in a variable pitch = mode.
 
AFAIU the problem is to find the exact = endpoints of=20 pitch travel. How does knowing the injector pulse width help with=20 that?
It will tell him how much power is produced in = combination with an rpm input, but does he also measure = airspeed?
 
Not bitching, just trying to get the = idea!!
 
Thomas J.
 
 
To: Rotary motors in = aircraft=20
Sent: Monday, January 23, = 2006 8:55=20 AM
Subject: [FlyRotary] Re: = Injector=20 pulseing ? Tracy ?

And how would Mark
Burton's constant speed = controller=20 react if the EC2 was switched to injector
disable mode.  = Depending=20 on how it was wired, it might suddenly sense zero
power or 2X=20 power.  Just thinking out loud.

Good = point=20 Dean.  If he only senses pulses to one injector, then it would = have to=20 be the primary, which is always active, unless you turn it off via = the=20 disable switch.  He may not realize we have the ability to = do=20 that, so it would be worth telling him about it.  =
 
Cheers,
Rusty=20
 
 


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