----- Original Message -----

From: Mark Steitle

To: Rotary motors in aircraft

Sent: Tuesday, August 17, 2004 7:20 AM

Subject: [FlyRotary] Re: First flight test report on Renesis

Paul,
You're building an SQ2000, right?  I looked at that kit a number of years ago, but they went out of business just before I was ready to send them a check.  Anyway, I had ordered their information packet with demo tape.  I still have the tape, so if you want it for your library, its yours.  I could bring it to Tracy's fly-in if you're planning on attending, or I could just mail it.

Mark S. 

At 07:57 PM 8/16/2004 -0500, you wrote:

Hi, Tracy.....thanks so much for taking the time to write such a detailed description of the first Renesis flight.  We all appreciate your efforts, and especially your efforts to share your results.  Best of luck in bringing down the temperatures.  Paul Conner, 13b powered SQ2000 canard

----- Original Message -----

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Monday, August 16, 2004 2:38 PM

Subject: [FlyRotary] First flight test report on Renesis

The first test created more questions than answers and much work to do.  Here is my development log entry for the flight.

 

Tracy

 

(8-15-04)

Flight test report on Renesis engine installation, N84TC  

OAT 88 – 90 deg

Humidity 90+%

 

Pilot impressions:

Takeoff  done with engine warm (~ 155 F) but water Temp was 207 on first check after rotation.  Reduced throttle and orbited SB for 64 minutes at ~ 1000 ft. MSL.  Engine very smooth with low cockpit noise level.  Water temp slowly fell to 195 – 197 at fuel burn of 5 – 5.5 GPH.  Engine RPM was 4300 – 4700 during flight.  Very brief (few seconds) full throttle test yielded only 5800 rpm and engine did not feel strong.  MAP appeared to be limited to ~ 28” Hg. Water temp immediately climbed to ~ 205 and power was reduced.  Oil pressure continued to read 100 PSI (full scale on instrument) as it has during ground tests.  Engine builder used 3rd gen rear pressure regulator and it has been my assumption that this was normal for it. Reset oil pressure high limit on engine monitor to 102 PSI to get rid of flashing alarm.  Oil temps were stable at 185F during entire flight.  Normal landing with engine temps falling rapidly during final approach.

 

Post flight engine check (engine still hot):

Gear drive had normal system lash

Turning over engine w/ prop, engine felt tight, higher friction than previous checks. 

Rotor compression felt normal (very good) but feel was hampered by engine friction.

Smell test through cooling inlets:  Aroma was very different than earlier engine installation although no sign of anything bad. 

 

Significant data:

Air temp delta on right side rad was 80 – 85 deg F

Water temp delta:  20 – 25 F

Oil temp delta:   ~ 30 F

Oil cooler air temp delta was ~ 45 - 50 F which was normal at the low power setting being tested.

MAP at WOT appeared to be 1.5 – 2.0 “ below atmospheric.

Analysis:  High coolant temperature was very disappointing as I had expected much better cooling with the improved diffusers.   Reasons for the high temps can be surmised by delta temps above.  The high air temp Delta would indicate one of two things:

 

1.  higher coolant temps indicating more heat rejection, or

2.  Lower airflow through rad.

 

The coolant temp was higher but only marginally (10 deg after stabilized at 195)  This would not account for a 30+ deg increase in air delta.  This leads me to believe that reduced airflow is the cause.   The diffuser on this rad cannot possibly (?) be worse than before so my guess is that the greatly extended duct divider that separates the oil cooler duct from the rad duct is having an adverse effect.  Oil cooling was not a problem and delta was in normal range so it was not hurt by the divider and may even have been improved. 

 

The water temp delta would indicate that the water flow rate is less than half of the previous value when deltas were in the range of 10 – 12 F.   Two possible causes come to mind.

 

1.  The coolant manifolds I made are too restrictive.

2.  The water pump design is less effective than the 2nd gen engine.

 

1 was a concern even while I was building them.  I thought they would be adequate because the coolant outlet arrangement does not appear to be any more restrictive than the previous setup.  OTOH,  the inlet setup could be significantly worse than before.  It has 90 degree fittings which could be a problem.

 

The water pump design is the same as the 3rd gen 13B which looks crude by comparison to the 2nd gen but has evidently been adequate in the auto racing environment.  It may require a much cleaner coolant path in order to achieve adequate circulation.  Or conversely, the 2nd gen pump may be much more tolerant of restrictive coolant paths.

 

Oil Pressure

The 100 (+?) psi oil pressure is a concern after learning from the engine builder that the 3rd gen oil pressure regulator (presumably equipped with a Renesis regulator spring)  is supposed to give pressure in the range of 70 – 85 psi.  This would indicate that the pressure is being regulated not by the rear regulator but the front pressure relief regulator which does not become active until 150+ psi.    As I write this, I decided to check the Racing Beat Tech manual for info on oil pressure.  According to their chart, the 93 -95 rear pressure regulator is set at 110 PSI !.  This leaves me with no firm conclusion about the oil pressure readings.  

Engine builder later confirmed that he had pressure spec wrong.  3rd gen is specified as 110 psi.  A 3rd gen car racer also said that his oil pressure runs 85 – 95 psi hot.  Off scale when cold.  Have canceled tentative plans to pull the engine for this problem.  I would still prefer to have a lower pressure regulator and will do this if I have another opportunity.

 

Low MAP

This problem is probably due to the relatively long and tortuous path between the NACA inlet and throttle body.  There is over 4 feet of 2.75” Dia. Aeroduct (SCEET?) between the two.  I was concerned from the start that this stuff would cause a pressure drop.  It will have to go.  Many more hours of fiberglass work required to fix.

 

Did prop pull-through test of engine ‘feel’ and it was same as earlier tests prior to flight test.  Compression of engine when pulled through in reverse is impressive.

 

Confirmed that the air temp sensor behind right rad was accurate.  In view of this I have decided to cut the duct divider back to near its original position and re-test.