Engine choices...
It sounds like things are coming together on this thread. Let me finish it off with the basics on my RV-9A with an ECI O-320 160 HP engine built by Penn Yan Aero. The thing here is to buy an ECI engine, no matter who builds it. Get the Titan cylinders with the Nickel-Carbide coating in the cylinders for better wear and rust-proofing. You can get the engine with low-compression 7.5-to-1 pistons for 150 HP and use autofuel... OR... you can get it with 8.5-to-1 pistons for 160 HP and use AVGAS 100 low-lead. One other thing to note, the ECI crank case has several advantages over the Lycoming. The oil galley has provisions for spray nozzles to improve cooling of the pistons and improve the oil flow along the cam shaft. The second feature is a dowel pin and socket arrangement that prevents the two halves of the crank case from shifting longitudinally. The Lycomings can do that shifting and as a result leak oil from the centerline gasket easier than an ECI engine. There are also machined recesses and O-rings around the transverse bolts in the crank case to minimize oil leakage around those bolts.
My RV-9A cruises at around 6 gallons per hour flying above 10,000 feet on cross-country flights. RV-9 and RV-9A airplanes love it up high due to the Roncz airfoil wing design. The longer wing span of that wing is what disqualifies the RV-9 and RV-9A from doing aerobatics. With the longer wing span, larger tail feathers had to be built to match. The larger RV-9 rudder is now standard on the RV-7 to make spin recovery much better. That may be where you got the idea the RV-7 was not intended for aerobatics. I saw a few older RV-7's at Oshkosh this year with the smaller original -7 rudder, but all the RV-7 and RV-7A kits today come with the RV-9 rudders. Van's offered all the older RV-7 and -7A builders the new rudders for free for safety reasons. I asked one of the pilots at OSH this year with the small rudder still on the plane why he had not changed it out. He said he had the rudder kit, but just had not built it yet since he does not do spins with his RV-7.
The RV-7, -7A, -8, and -8A all come with the same aerobatic wings and tail feathers. The RV-8 and -8A still use the smaller rudder, since the narrow fuselage (tandem seating) does not limit rudder authority in spin recovery as much as the RV-7 and -7A which have the wider fuselage (side-by-side seating).
The other thing about the aerobatic airplanes, they all have tapered horizontal stabilizers and elevators. The RV-9, RV-9A, and the RV-10 all have constant chord horizontal stabilizers and elevators for more surface area back there and positive control behind the longer main wings up front. The RV-9 and RV-9A wing span is 28 feet, and the RV-10 is 31 feet.
There are a lot of RV-6, -7. & -8 airplanes out there with 180 HP and 200 HP engines going over 200 MPH, but burning a lot of gas to do it. I find that I can get up higher than those guys with the aerobatic wings, find better tail winds, and burn less gas and not arrive too much behind the guys with more horses up there. With the longer wing span, the 160 HP RV-9A can climb very well compared to the shorter wing RV's with 180 HP up front, and do it on less gas. As for the top end max speed Van's published on the RV-9 and RV-9A, been there, done that doing 193 MPH at 1,000 feet MSL. With the 160 HP engine, I can go "over square" on the power settings since O-320 the engine will not over-stress my Hartzell constant speed prop. To get the 193 MPH, I was turning 2,300 RPM at full power (28 inches of manifold pressure) to get the 193 MPH on a high-speed pass down low about 200 feet above the runway at my local airport. Granted, you cannot do that very long since the engine will get overheated. That does not even consider that the fuel burn doing that is around 11 gallons per hour through the engine. Now you know why I like to get up high, lean the engine, and cruise at 160 MPH true airspeed.
And the last thing to note, the guys at Van's all want to fly in the RV-9A or the RV-10 when they go to the big regional fly-ins or Oshkosh where Van's sets up their exhibit booth.
You will find my story of construction of the airplane, and all my flights documented on my web site
www.n2prise.org with lots of photos and some video movies, including arrival and departure from Oshkosh this year. You can also see the RV-8 with an ECI O-360 180 HP engine that is being built by my hangar mate. I am coaching him during the construction and posting his process on my web site. Look for Wendell's RV-8 project from my home page to learn about that.
Jerry K. Thorne
East Ridge, Tennessee
RV-9A N2PZ Hobbs = 207.3 hours
www.n2prise.org