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How about a second CAS on the flywheel, with an A/B switch for redundancy if you are worried about a CAS failure?
Brian Trubee
-----Original Message-----
From: Tom Walter <roundrocktom@yahoo.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Thu, Sep 15, 2011 5:24 am
Subject: [FlyRotary] Re: The good news and the bad news......
Yep... so the irony is a 100% redundant CAS has to be 360 degrees off from the first one.
Since both can not occupy the same physical location the software needs an offset.
Rotor Two then needs 180 degree offset if it is the master pulse.
Tom
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wednesday, September 14, 2011 7:53 PM
Subject: [FlyRotary] Re: The good news and the bad news......
Tom,
The 13B requires 1080 degrees to fire all six rotor faces. This means that it fires every 180*, not every 120*.
The 3-rotor fires every 120* because it has 9 rotor faces in order to fire all faces within 1080 degrees.
Mark S.
On Wed, Sep 14, 2011 at 5:21 PM, Tom Walter <roundrocktom@yahoo.com> wrote:
Could you enlighten me?
I'm missing something pretty obvious, but allowing for one "missing spark event" All my 120 degree trailing offset means is that I'm really firing off rotor face 2, which the ecu thinks is rotor face 1. No camshaft, or cam timing issues, but what the heck am I missing?
Tom
From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wednesday, September 14, 2011 5:06 PM
Subject: [FlyRotary] Re: The good news and the bad news......
Short answer is no. It's never that simple.
Tracy
Sent from my iPad
Tracy,
If the second CAS sensor was set up at 120 crank degrees after the first one, wouldn't that be a zero offset?
My thoughts: Rotor spins at 1/3 crank speed..... so with 720 crank revolutions, that is six ignition events. So each ignition event is 120 degrees apart. Yes, I tend to think in 720 crankshaft degrees, to many years in automotive piston engines.
Tom
From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wednesday, September 14, 2011 4:43 PM
Subject: [FlyRotary] Re: The good news and the bad news......
The relay is not needed in this hypothetical fix. The EC2/3 already has 2 CAS inputs. All that is needed is a hard definition of sensor offset so the software can be written appropriately. ( I'm assuming a Renesis engine which has only one CAS in this discussion.)
The CAS output is an AC voltage sine-wave that varies with engine speed. This is true for both Mazda and Subaru engines (and almost all others). The sensor is a variable reluctor type.
Tracy
Sent from my iPad
On 9/14/2011 1:48 PM, Al Wick wrote:
<What kind of signal is on the CAS line
If memory serves, it's 0 to 5vdc square wave.
<Could it go through a relay safely?
Yes, but I'm not sure where you are going. You thinking normally closed contacts to OEM CAS, norm open to backup CAS? You still have to manage angle offset. Would be unfortunate to have moisture in relay or turbulence disrupt CAS. Likely not going to end up with safety improvement. Good creative idea though.
The rotary engine CAS is set up on a bracket near the front pulley. I was envisioning a system where you had a sensor in exactly the same spot on the other side of the toothed wheel. You might need an offset alternator pulley to make room for it - but then you don't have to worry about angles/offsets. It's just a second sensor, ready to go - flip a switch and try an engine restart. If relay reliability was a concern there are always SSRs or even just good switching transistors...
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