Powersport rotary garnered another notch on their reliability belt when two RV8R’s piloted by Jim Clark and Jerry Gustafson completed a round trip to Oshkosh from Napa, California, a 2300 mile round trip.  While 559JC did experience a prop electrical brush failure, the engines performed flawlessly throughout the trip.                                                                                                                                         
Both aircraft stopped at Osceola, Wisconsin, home of Powersport Aviation, for an ECU refinement that helped but did not cure the deceleration engine roughness when the throttle is abruptly retarded.  This in no way compromises the safety of the engine, but rather an annoyance.  This roughness can be alleviated by reducing the propeller RPM prior to reducing the throttle.  Airplane 559JC was also fitted with a newer type throttle position sensor that is expected to eliminate the wear and eventual replacement of the current TPS.
 Here is an update on the engine and what we have done to eliminate the problems we encountered;

1.  Heat dissipation-----this remains our number one priority.  We have made good progress correcting weld cracks by machining the exhaust flanges by using 321 stainless and 2" primaries dumping into 2 ½ secondaries, coupled with a bellows system.  We were able to incorporate the muffler in the cowling with the aid of an exhaust shroud and porting ram air through the muffler bay. Oil and coolant temperatures have been reduced through the use of a tight pressure cowl.  Both temperatures approach maximum on a hot day with a long taxi.  At take off temperatures above 90 degrees Fahrenheit a climb speed of 135 versus 115 with a slight reduction in prop RPM (2620-2500) keeps the take off temperatures below 230 degrees Fahrenheit.
 We made a 96 degree Fahrenheit, 4600 feet density altitude take off with this technique and still climbed out at 600 feet per minute. We believe we can reduce the coolant temperature by 20 degree Fahrenheit with an improvement in radiator position and efficiency.  Work in progress.  At present the oil temperature during operation are within acceptable limits. 

     
2.  Fuel burn and its economies-----We’ve done extensive work on the mapping of the engines and have achieved good results for our efforts.  Our goal is to reach a complete burn of the fuel provided by the injector system and ignited by our twin ignites, has been achieved at all phases of flight, except the "deceleration phase"; where the engine RPM and throttle opening do not match and result in a rich fuel to air ratio, causing a rough engine operation.  This, too, can be alleviated by technique of the pilot.
 Additionally, we’ve installed a mixture control, allowing a 10% leaner or richer mixture as compared to the stoichiometric setting.    We achieved 9.6 gallons per hour; at the programmed ECU setting (no leaning was attempted).  We are further testing the feasibility of 92 octane, no lead auto gas.  (Updates on this forthcoming).  We’ve also tested various spark plugs and have settled on a racing plug from NGK.
 A test on retardation and advancement of timing has been achieved with inconclusive results to date.
 Proper leaning procedures at altitude appear to be accomplishable by the EGT gauges.  However, to date we do not have a precise enough EGT gauge to report this as an acceptable procedure.  Again, this should be solved in the near future.
 With regard to the option of burning no lead auto fuel, all the reasons are positive except one; that is, supply availability at the airport.  No lead fuel at 92 octane would, of course, be cheaper by about 75 cents per gallon; possibly more because of state road taxes we would be exempt from paying.  It is a much cleaner burning fuel; therefore it has less spark plug fouling and combustion chamber lead deposit buildup.  The question remains whether 92 octane can produce the power that 100 LL does.

3.  Electrical System-----Refinement of the electrical system has us at two batteries and one alternator with the accompanying safeguards.
Overload protection via a 60 amp fuse in the "B" line from the alternator. Over volt protection via the crowbar circuit in the alternator field line as well as the internal regulator in the alternator .Battery isolation can be accomplished by the keyed battery switch. The Essential buss is protected by circuit breakers and an emergency power / load shedding switch along with blocking rectifiers. With the loss of the alternator, protection is provided by the dual batteries for two hours minimum to the essential and hot battery busses. The Dynon D10 efis system with internal battery also provides essential flight information for at least 30 min. Our entire electrical systems mirror Bob Nuckols' one alternator-two battery design found in "aero electric connection".

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Last modified: September 15, 2005