So, Lowell, does that thing cruise at about 190 knots, or what?
No real comparisons as both my IVs had the fairings from the get go. I pretty much did the same fairings on my first Model IV And most local flights were less than max cruise. On our group flights we always flew to the speed of the slowest airplane to keep the loose formation together. For me, at least, the fairings helped mostly with fuel burn. On one of the early flights to the Idaho Back Country, our fuel stop at Winnemucca, NV is still talked about. Six airplanes fueled and the fuel burn on the first leg was very interesting. The Rans S-6 Took 13 gallons. The rest were Kitfox Model IVs and fuel loads ranged from about 9-1/2 to 12 gallons. I topped up with 7.2 gallons. It was a three hour flight. The S-6 ran a 912ULS where four of the Kitfoxes had the 912 UL and the fifth ran behind a 582. My typical RPMs with the group ran in the discouraged under 5000 RPM range. My current IV, will cruise at just below 110 mph behind a 912UL. I think I could get a few more miles if I faired the spring struts and cabane on the landing gear. Then I just might pick up a Zipper from friend Hal.
I guess I should mention that I have never felt elevator authority was less than adequate, and three pointing has never been a problem with the gap seals.
Three pictures of the 1998 (earlier) Model IV.
The Horizontal stabilizer showing the tip.
horizgapseal1.jpg
The Horizontal Stabilizer.
horizgapseal4.jpg
A drawing of the method used to make the 1998 gap seals. The later model was made of fiberglass shapes without foam except for the ribs.
Gap Seal X Section.jpg