Two RV-8's powered by rotary engines make 1200 mile round trip
to the home of Van's Aircraft
By ANN Correspondent Christopher Armstrong
The yearly homecoming of Van's aircraft was held September 4-5.
Ken Scott, Vans Aircraft employee in charge of Technical Support
and Publishing, said that there were 85 aircraft on the ground at
one point, and that 100 to 120 Van's RV builders flew in from all
around the country to Aurora Airport (OR) to attend.
Scott spent much of the day flying an RV-8A with noted English
aviation photographer Ed Hicks sitting backwards in the rear seat,
shooting air-to-air pictures. The Vans homecoming has become the
centerpiece of the Van's kit aircraft builders' and flyers' year.
The main events included a barbeque on Saturday and a banquet on
Sunday. Groups of flyers were coming and going, for flights to the
Spruce Goose museum, to practice formation flying, and to fly over
some of the amazing local scenery; Mt. St. Helens, the Oregon
coastline, or anywhere there was a restaurant.
Scott said that along with the second RV-10 and the two RV-10's
flying in formation, two RV-8's powered by Mazda rotary engines
attracted the most interest. They were flown about 1200 miles
roundtrip from Napa (CA) to Aurora Airport by their builders,
Jim Clark and Jerry Gustafson.
Clark's airplane, N559JC is painted in a blue camouflage scheme
and received its certification on April of this year. The RAF
Spitfire inspired brown camouflage with gaping toothy mouth on the
inlet is Gustafson's N8388SJ, which received its certification one
day after Clark's.
These are the first two RV-8's flying with Powersport Aviation
215 rotary engines. The Powersport engine is a highly modified
Mazda 13B engine. The Mazda side intake ports are filled and custom
peripheral intake ports with integral throttle butterflies are
machined into the rotor housings. The engines use high pressure
electronic fuel injection and ignition controlled by dual engine
The engines produce 215 hp at 6000 rpm and weigh around 325
pounds firewall forward. The rotary engine has a very small frontal
area which allows the planes to use custom cowlings to reduce
parasite drag and improve propeller efficiency, and give the RV-8's
a more replica-fighter-like appearance. In the cockpit, Clark and
Gustafson have used a Dynon EFIS for primary flight display and
Powersport's MFD for engine instrumentation and GPS navigation
On April 25, Clark reported to other RV builders: "We had many
moments of soul searching and bouncing our ideas off others and
each other before we decided to purchase the Mazda rotary. Some of
the reasons we chose the 13B were: the rotary engine weighed 65
pounds less than a comparable IO-360; there is 15 to 25 more
horsepower; smaller face of the cowled engine offered less parasite
drag; there are only two moving parts and therefore less wear
and tear; also, less things to go wrong; an efficient liquid
cooling system kept wear to less than air cooled engines and
allowed overhaul times to about 3000 hours; overhaul is simple and
inexpensive, costing $1200 per overhaul.
"The drawbacks; putting ourselves against a tried and true
engine that Van's had engineered and tested for many hours; there
were heat problems, such as rotary produced EGT of 1600 degrees,
oil temperatures of 230 degrees and coolant temperatures of 190 to
210 degrees. We had to figure a way of dispatching this heat and
keep the exhaust system contained within the engine cowl."
Clark described the flight characteristics of the Rotary powered
RV-8, "Normal operational ranges: propeller 1800 to 2600 RPM, 1000
to 6000 engine RPM, prop is reduced by 2:29: 1 with reserve power
to 6600 RPM and manual propeller operation at 6000 RPM, EGT
1400-1600 degrees, oil temperature 225 degrees, liquid 190-200
Clark continued by explaining that "gas consumption is running
around 11 to 12 GPH. I expect this to improve with a more efficient
operation and pilot familiarization. We've had no cruise test over
3000 feet to date so these figures are estimates. The rotary
engine, modified as it is, requires mixing two-cycle oils with
our fuel at 100:1. We have been using 100/130 AV gas, but the
rotary engine will run on 87 octane unleaded automotive gasoline.
We ground tested initially with 87 octane unleaded."
"Our empty weight comes in at 1056 pounds unpainted. The engine
itself contributed 65 pounds of savings; the M/T propeller
(constant speed electric) saved approximately 19 pounds. We used
aluminum gear, saving 17 pounds of weight. The Dynon EFIS system
saved 4 pounds. All together, we saved a little over 100 pounds
with the rotary engine."
"Last but not least, the matching of Van's RV-8 and the Mazda
rotary seems to fit well. Although I don't have a lot of
experiences in other RV-8's, it seems to be very nimble, powerful
and responsive. It would be a good test to compare the Mazda
against the IO-360."
"The CG with a light fuel load and pilot only, carries a fwd CG
and seems to lend itself to wheel landings as opposed to full stall
landings. The P-factor on takeoff, with power slowly applied,
presents no significant tracking problem. Full power takeoffs at 80
KIAS uses about 250 feet of runway."
Ken Scott and the staff of Van's Aircraft were very pleased
that the 2004 Homecoming was a safe, incident-free event. With so
many aircraft, flying so much, the professional flying exhibited by
all the pilots was crucial to the success of the event.