Steve,

At one time Tracy’s started cutting ignition ( I think) at 7500 rpm. If I forgot to switch the prop controller to automatic I could easily exceed 7500 pm. Did it at Charlie’s a couple of years back and scarred the pilot and his neighbors. I quickly realized the problem and switch the prop to auto and it took a few seconds to correct. I limit max rpm to 2400 prop.

Bobby

Hi guys

I’m wanting to inflight test for the best RPM for peak power of our 4 port Renesis with variable pitch prop (No constant speed control at present).
On Takeoff at Full Fine we hit 6900 after a few seconds and then rpm builds to 7400 by 500 feet and 110 KIAS
I’m wondering if we are well past the peak torque and would be better off at a lower rpm.

Am I right in thinking the following would use the aircraft as a Dyno to establish rpm for best power?

1. Set up level flight (auto pilot)
2. Maintain WOT and constant mixture (best power - say 0.9 Lambda - 13.2 AFR) via Wideband O2
3. Vary RPM in 200rpm increments for 2 minutes each setting between 5600 and 7200 by adjusting prop pitch
4. Note Fuel Flow and IAS (Logged on Dynon Skyview)

I’m thinking this would give me an indication of best RPM for highest power.
Our Inlet is just under 19” long, measured from the side face of the engine.
So I’m thinking peak torque may be around 6400 rpm.

Your insight would be appreciated.
Thanks

Steve Izett
Renesis 4 port RD1C (2.85:1) Inflight Adjustable Prop






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