I took my plane to Van's last week for a head-to-head comparison
with their RV-9a. Dick Reeves joined me for moral support. Van's
plane, N129RV, sports a Lycoming O-320-D1A and a 2-blade Hartzell
CS prop. Mine, N29GJ, an Eggenfellner Subaru 4-cylinder with
supercharger and 3-blade MT CS prop. I weighed in at a calculated
empty weight of 1183 lbs, which is 105 lbs heavier than Van's. Two
AP servos, 9 lbs ballast, a little extra paint and maybe 5 lbs in
the panel would account for about 1/3 of that. I think the rest is
engine related ? 2nd battery, supercharger, muffler.
It was a beautiful blue day. In the 70's on the ground and 51 F at
8000 feet by afternoon. Ken Krueger was very thorough. Both he and
Ken Scott were happy to have an Eggenfellner visit Van's ? in fact
several on the staff came out to welcome me. Both Ken Scott and Ken
Krueger took short flights in the right seat and I think were
favorably impressed.
The purpose of the first flight was to make some qualitative
observations about 29GJ. The plane was then fueled and weighed, as
was Van's plane. Pilots were also weighed and Ken took on 35 lbs of
ballast to make up for his light lunches and bicycling habit.
The 2nd flight was a full-throttle maximum climb to 8000 feet AGL
pressure altitude (we set ground elevation of 200 ft to zero on the
altimeter). Timed from roll to 8000 ft was 6 min 9 sec for Ken, and
6 min 40 sec for George. A 2nd climb test later took 6:10 and
6:54. So climb advantage went to Van's and the 105 lb difference
would, I think, accounts for much of the difference. My IAS isn't
calibrated well and Ken tried to match my ground speed to yield a
fair comparison. These climbs at 2700 rpm resulted in temperatures
as high as 236 F. I always take off at 2500 rpm and usually reduce
to 2300 after 1000 feet, so don't usually see temps above 200 F.
Cruise temps are often right at 188 F, both oil and coolant.
The next part of this flight was a 5 minute speed test ? full bore
at 8000 density altitude. Ken gained about ? mile on me and
registered 6 mph faster on the GPS (a one-time look). The Subaru
consumed about 6% less fuel for this flight.
After returning for refueling and something to eat, we were back in
the air for the 3rd and last flight. We did a 2nd climb test and
then a cruise to Eugene and back ? a side-by-side flight of about
170 miles round trip at 8000 density altitude. I chose the speed
and went with 2300 rpm WOT on the outbound and 2000 rpm WOT for the
return. We switched tanks to separate cruise efficiency from the
climb and descent. The Subie used 2.5 % less fuel for this flight.
Interestingly, the Subie used 8% less fuel than the Lyc for the
climb & descent portion, but about 2% more for the cruise portion.
Conclusions? To me, the planes seemed remarkably well matched in
performance. Horsepower from the 2.5 L engine/supercharger combo
pretty much matches the Lyc O-320 under 8000 feet and would yield
some advantage over a normally aspirated 160 hp Lyc above that
altitude. I'm happy with the results and proud of my airplane.
Van's 9-a is a light little hot rod that took me (if only slightly)
in both climb tests and full-out speed. If only I had removed those
tie-down rings??.. And having to refill with 100 LL at $4.00/gal
reminded me of another reason I like my Eggaru. It was a good day!
