Dave,
You must have been reading my mind as I had recently decided to do exactly what you
have recommended to Chris...............Get it in the air naturally aspirated first then add the
Turbo after any bugs (airframe, cooling, etc) are worked out.............
Since we have several turbo/rotary a/c flying successfully it has been a mystery why Chris
has had so much trouble with what appears to be detonation and has never been off the
ground...........I think you have hit on the reason...........I seem to remember of several engine
runs reported by Chris at high manifold pressure, high coolant temps and as you mentioned
probably high intake temps with little or no airflow across the intercooler.............
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: Dave <david.staten@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Fri, March 4, 2011 1:25:40 PM
Subject: [FlyRotary] Re: Knock sensor and indicator
On 3/4/2011 8:43 AM, Chris Barber wrote:
Since I have had an issue with detonation, I am contemplating adding a knock sensor. What do y'all know about this addition. I do not believe Tracy's EM has a provision for a reading, so, what might be a good route to take. The brief research I have done shows different frequencies, types etc. What would be correct for a rotary, both as to a sensor and something to notify me in the cabin? Thanks. I am about to replace ALL my apex seals and soft parts and hopefully finally lick this issue....hopefully....did I mention hopefully...determinably...persistent? (heck, I wasn't planning anything else this weekend <g>)
Chris
The stock block rotor housings have a fitting in between the plugs to have a knock sensor that ties into the stock ECU.
However, the response time required, from what I've read, from the time detonation is detectable to action needing to be taken is very very small.. fractions of a second.
I suspect that all the time and expense you are contemplating undertaking would simply be to install a light to tell you when its time to tear down the engine again, because it would be too late to avoid the damage.
Our approach must be to avoid detonation, not mitigate its effects. You would get more benefit out of measuring your intake temp (as an aux temp on the EM) after the turbo intercooler to see where your charged air temp is hanging at, and trying to cool that effectively. Running boost on the ground with no airflow across the intercooler is liable to result in intake temps over 200 degrees due to
compressional heating of the intake air. If I remember right your fan is on the radiator, and there is not a fan on the intercooler.
There was a reason when we started this that I recommended strongly about getting the plane flying in a normally aspirated mode first.
Dave.