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Reflections On My Homebuilt

By Merv Friesen

Merv Friesen enjoys flying the Sonex he built. For those of you who haven’t flown a Sonex before, Merv was happy to file this flight report while he waits for the spring to come once again.

Taxi – The Sonex has a direct link tailwheel. I find that it taxis very easily; I hold the stick back and steer with the rudder pedals. It goes where you point it. Due to the direct link, though, it doesn’t turn very sharply, and you have to consider runway width and make your turn accordingly. I think for this reason the makers designed a single lever brake. That way, you won’t stand on one brake and skid the tail around.

Takeoff – I align myself in the center of the runway and slowly apply power for takeoff, holding back stick until I feel it’s going fast enough to raise the tail. Once the tail is raised, I hold it straight with the rudder and lift it off at about 60 mph. At the Steinbach North Airport in Manitoba, Canada, runway 32, I’m off and looking down at the hangars by the time I reach the first taxiway when flying by myself. With two aboard, the ride along the runway is longer. So there’s a noticeable difference when flying at gross weight.

Climb – By myself, I’ll typically climb at 1000 fpm on climb out. With two aboard, it’s closer to 600. The climb test was 640 fpm at gross weight. At Steinbach, I’m at circuit altitude on crosswind. I have the 54” x 48” prop, which is more of a climb prop than cruise prop. I wanted it because I thought I might keep it at a private strip here at Kleefeld. It’s 1600 feet long, and I thought the finer pitch prop would do better here. As it is, I rent space at Steinbach North, and so I have 3000 feet of runway to use.

Sonex

Cruise – Sonex Aircraft says 130 mph on the website, but I don’t go that fast. I’m not sure of the difference. They probably tested their speeds at higher rpm. I see about 120 at 2850 rpm; I thought I would target that as a cruising rpm. But redline is 3300 rpm. I know that some cruise at higher rpm and their speeds are higher. When I tested at 3200 rpm and 3300 rpm, I was indicating over 140. So the plane is capable—it depends on where you set the power.

Landing – I typically fly the circuit at Cessna 150 speeds. I like to get to 90 mph on downwind and pull the first notch of flaps. Then I slow to 80 mph on base and pull the second notch of flaps. I like to hold 70 mph on final and come over the runway at 60 mph. It stalls at 40 mph, so I consider that to be on the safe side. I’m sure that with more experience and the need to land shorter, I can reduce those speeds. I do have the third notch of flaps and use that when the wind conditions are straight down the runway. I started with three-point landings and now try to do wheel landings. I think right now it’s a combination of three-point and wheel landings. I probably slow it down and let the tailwheel get low before I plant the main wheels on the runway and hold the tail up until it slows down. There’s good rudder authority, but the shortness of the plane means you have to be alert.

Stalls – The airplane with just me aboard slows to about 40 mph and then stalls. The nose doesn’t drop much and the airplane descends, though I don’t remember at what rate. Add a bit of power, push the nose down, and you’re flying again.

Aerobatics – I haven’t had the aerobatics restriction flown off yet. The aircraft does turn with a little bit of rudder input, and it’s easy to put it in a steeper turn. I have no doubt that it will do loops and rolls easily. There are movies on YouTube that show people doing aerobatics with the Sonex.

Weight and Balance – The 2200 is quite light. The weight and balance lean toward the rear, so I added about eight pounds of lead to the nose to improve the balance. At this point I’m confident that I can fly down to 15 liters and stay within the weight and balance with a normal load. I just calculated this as an example: takeoff tank full at 65 liters, pilot 165 pounds, passenger 160 pounds, 20 pounds baggage, 1099 pounds total (1100 pounds gross weight), 10 liters fuel at landing. Takeoff center of gravity (CG) is at 28.5 percent, and landing is at 31.9 percent. The CG range is 20 to 32 percent. So, I can stay within the CG, but I have to be careful. You just learn to stay within those parameters, and all is well. Those with the VW and Jabiru 3300 will have a more forward CG but will be able to carry less load.

Engine – The Jabiru is a good starting, smooth-running engine. I have solid lifters, and so I have to adjust them frequently. That’s a good thing because I’m checking my engine frequently. I use about 1.5 ounces of oil per hour and about 14 liters of fuel per hour. My Jabiru has been running well for the first 80 hours. I’ve been adjusting the jets on the Bing carburetor to bring the exhaust gas temperature down in cruise. I’m close but will adjust further this flying season. I’ve been up to 6000 feet, and it was working very well.

 
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