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 management computers.

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 display.

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 degrees."

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.

FMI: www.vansaircraft.com/public/vans-hc.htm, www.vansairforce.net/rv_travel/EdHicks/EdHicksRVPhotography.htm, www.powersportaviation.com