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Hi Steve,
Congrats on the progress; I'll be following closely. Can you continue to share details about your tweaks to the wedge diffuser? Inlet/outlet area configuration, rad face area/thickness, etc as you make changes, as well. As you learn new stuff, I'd love to be able to incorporate your findings in mine. I've got even flow across the core, but no real perspective on how efficient the diffuser itself really is.
Thanks,
Charlie
On 2/20/2021 5:18 PM, Stephen Izett stephen.izett@gmail.com wrote:
Congratulations Finn.
Some reflection from the data:
RPM’s only get to ~5650rpm - Is it over propped?
You appear to have been quite conservative when you pulled the power back with Eng temps being well below 200.
You were probably maybe making ~150hp depending on your intake length etc. The OT being quite low.
Looks like you need to collect some more data.
What is the exit area and can you measure the cowl pressures?
We are continuing to fine tuning our cooling.
Changes to our diffuser wedge shape has made some significant improvements.
We mechanised our right hand (bottom rear) cowl flap and flew the Glasair last week to test.
Closing the one cowl flap at 140 KTAS yielded a 5 KTAS increase and 2 deg C rise in H2o & Oil temps.
Based on this data we’ll now mechanise the left hand cowl flap and test.
Our experience is without doing the science and measuring pressures across the radiator cores we are just spitting in the dark.
Again, congratulations and thanks for your help.
Cheers
Steve Izett
Perth Western Australia
Renesis 4 port, RD1-C EC2 EM3 variable pitch Prop
On 21 Feb 2021, at 3:25 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
N214FL left the ground this morning for an 18 minute flight.
Main concern was engine (water) cooling. As you know, cooling is a compromise between drag from unnecessary air through cowling and adequate cooling during normal flight conditions. Climbed to 1,500' before pulling back on throttle to see if coolant temp would stop rising. It did. Still, I think I erred in too small fluid inlet openings in the A/C evaporator cores I used for radiators. Some more work in that area is in my future before hot days arrive.
Cut the flight short due to a bit of smoke (didn't smell anything) briefly observed low in the cockpit at full throttle later in the flight. To be investigated.
Van's RV-4 with Mazda 13-B Renesis (RX-8) stock engine.
RWS 2.87:1 Propeller Speed Reduction Unit
RWS Engine Controller and Monitor (modified)
Performance Propeller 76x88
Empty Gross: Approx 926 lbs.
Engine log attached. Unzip and open with Excel.
WTALR: Water temp after left radiator
WTARR: Water temp after right radiator
Use EGT and CHT Ref to compare to OAT and adjust accordingly.
Finn
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