RV9798 said:
Vern,
I will implement that aileron modification in my 9 and will try that.
I would't mind comparing some performance figures with you. I am also thinking about making a plenum. I want to go 10mph faster without making another plane. I am sure I can squeeze a couple more mph from my 9. Any suggestions for easy gain of speed?
Cheers,
Pete
My 75% cruise is 164 knots, 189 mph. That's a few knots faster than Van's numbers, and I need at least 9500 feet p.a. to keep the prop below 2600 RPM.
By comparison, this is about 3-4 knots faster than a friend's RV-6A with a similar engine in side-by-side comparisons. The difference is that my engine is a Superior/ECI cylinders roller lifter engine. I think the Superior sump provides slightly better breathing (higher MAP). This is confirmed by my MAP readings vs. pressure altitude.
Here's some cheap ways to increase trip speed:
1. fix your roll trim problem
2. keep the ball centered
3. Use an autopilot
4. keep the weight down
5. keep the cooling drag to a minimum (reduce inlet size) if CHTs ok.
6. When climbing to cruise altitude, climb at Vy. Vy decreases by about 1 knot per thousand feet.
7. Couple your GPS and EFIS in order to get wind vectors. Change altitudes to benefit from tail wind or reduced headwinds.
8. Slow down in cruise/run best econ mixture to save a fuel stop. Alternatively, install extended range tanks.
9. Cut two feet from each wing to make a 'clipped wing' 9A. See if that helps. This may not be cheap if it doesn't work and you have to install new wings.
10. (My favourite). Cruise high, push the nose down and let 'er rip (watch Vne!) when approaching destination.
Seriously, if you want to go long distances fast, the extended range tanks are probably the way to go. Eliminating a fuel stop saves time and money. They are a pain to install and plumb, though.
If you are just looking for 'bragging rights' speed, though, I think you build an F1 Rocket, or get Norm to build one for you.
Personally, I have more fun with the formation flying than x-country.