Homebuilder's Workshop: Learning the RV-9A
By Ed Wischmeyer
So with the RV-9A in hand, it was time to learn to fly her properly. I’d made a few landings with the previous owner, and knew that I could land her safely, but that’s not nearly the same as flying the plane well.
Some of the quirks had to do with keeping the cylinder head temperatures at an acceptable level on climbout. A friend and I pulled the top cowling and found air leaks, fixing the easy ones at the front of the cowl. The engine still runs warm on takeoff and climb, but at 110 knots or so, the CHTs stay below 400 (most of the time) and the rate of climb is good, even with a fixed pitch prop. Even with the air leaks fixed, the engine air inlets are sized for cruise, so the high temperatures in climb may just be a fact of life.
With that relatively high climb speed, the RV-9A would not be good for mixing it up with Cessna 152s and 172s in the pattern. You’d eat ‘em up in the climb part of the traffic pattern.
The level off technique is like in other airplanes, only more so. In my Cessna, I’d start easing the power off 100 feet below the desired altitude, with the climb speed being the same as the pattern speed, 90 MPH or 80 knots. In the RV-9A, pattern speed is 60 knots, way slow because the plane doesn’t go down and slow down very well. The technique is to pull the power back to 1,200 RPM, traffic pattern power setting, a full 300 feet below pattern altitude. This lets you coast up and slow down at the same time.
While practicing in the pattern, I’d noticed a few peculiarities, like with full flaps (32 degrees) and idle power, the airplane only descends at 500 feet per minute. Sure, it’s clean and has a big wing, but… And when I land on a long runway in the touchdown zone and let it roll out, 5,000 feet later, the plane has only slowed to 38 knots. Takes lots of braking to slow her down.
Yup, it’s the idle speed. Or was. Cold, the engine idled at 700 RPM, but warmed up, the idle was more like 950. The idle mixture was too lean as indicated by no RPM gain when pulling the mixture back to cutoff. And there was a jam nut missing on the mixture adjustment clevis at the carb.
A friend fixed all those for me yesterday, and the RV-9A now should fly a whole lot more like an airplane, and maybe I’ll be able to fly faster patterns and still slow down for landing. The idle speed (warm) is now 550 RPM with a 40 RPM increase when the mixture is pulled back to idle cutoff. Need to get over the last symptoms of this stupid bronchitis before I go try it though.
My RV-8 has the same out of adjustment symptoms, but with the short wing and constant speed prop, it has no problems descending like a brick when I ask it to.
With a new (to you) homebuilt, you always need to be careful about everything, and I’ve found some electrical quirks in the new bird, but I wasn’t expecting to find anything as generic as the carb being misadjusted or maladjusted, perhaps…
The RV-9A has a Garmin G3X touch screen on the left side, and I got the plane right after Garmin made round dials available on the G3X. The G3X is pretty slick, and there’s a lot to like about it, but it’s not perfect. The two major, and these are serious, unacceptable on a factory built airplane flaws: (1) the primary flight display does not clearly annunciate the source of the data you’re navigating with. If it says GPS and somewhere nearby it says “INT,” then the G3X is using the Internal GPS, but if it just says GPS without the “INT,” then it’s an external GPS, like the GTN 650 in my airplane. Having the lack of an annunciation convey meaning is a major no-no. A minor point, perhaps, but the kind of minor point that is a link in an accident chain, waiting for the other links to show up; and (2) there is no full time display of electrical system health. There is a narrow, vertical stack of engine instruments, and you have a little bit of control over what’s shown there, but not enough. The built-in algorithm gives precedence to fuel flow and fuel pressure over volts or amps, for instance. I’m planning to install a separate voltmeter.
In order to get rid of hand held devices in the cockpit, especially under a canopy, I’m consolidating the avionics to almost all G3X. As I bought it, the airplane had four different display or autopilot systems from four different manufacturers, but I value uniformity more than the abundant diversity of manufacturers. Part of my consolidation is the Garmin autopilot, and it’s really slick. I hope I’ll still think so after I install it and get it working.
There are two servos for RV-9A autopilots, the roll servo in the right wing and one behind the baggage compartment, next to the elevator bellcrank. I got the old roll servo out without too much hassle, but since I’d left the iPad at home with the installation manual, I didn’t install (physically) the new one––and the wiring is a whole ‘nother kettle of fish. A friend came over and helped me this afternoon, with outside temperatures in the high 90s. We got both servos installed, physically, but wiring will be a multi-session process.
The installation manual for the G3X system, will all the hardware and airplane permutations, and all the settings, is more than 700 pages but fairly readable.
What is in the future for the RV-9A? Constant speed prop for sure, the interior needs some fix-ups or maybe replacement, and if I get exorbitant, a new paint job.
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On another note, Gulfstream did not extend my four-year contract, as is their custom, and I’m now officially retired–at least until something really fun and challenging comes up in avionics design, aviation safety, human factors, teaching, journalism, whatever. Then again, I’m glad to have the time off so that my back can continue to heal from the spinal fusion surgery last fall so that I can get the house completely organized and know what I’ve got and where it is, especially the tools in the garage, or guy-rahg, as it is now pronounced.
