Real World Performance

[MsMiner]

I was wondering what kind of cruise performance people are seeing on 100HP I would like to build the kitfox s7, because the published performance data looks really good to me, but I don't know how far this is off of reality.

I'm looking for climb performance, cruising speeds and on what hp you're getting those numbers. I've read a couple of threads on it, but the data has been based on the KF IV with an 80 hp rotax.

[Dave S]

Mark,

Mileage will vary given the fact that there are no two kitfox builds alike; however, the experience with our S7 & 912ULS kitfox causes me to think the published data is pretty close.

There are quite a few prop combos out there; and, innumerable ways to set up a ground adjustable prop.

The 912ULS is actually 95 HP if the optional airbox is not installed, according to Rotax; and, few install the airbox.

On our S7, 912ULS with the airbox and a warp drive prop set to provide the Rotax minimum RPM of 5200 @ full power @ best rate we will see 110-115MPH @ a cruise setting of 5400 RPM which also turns 5 GPH. Climb rates vary with load and weather conditions; but, 800 to 1200 FPM covers the variation I see. ( and we are flatlanders out here)

For anyone who can afford an air adjustable prop, I would speculate that cruise speed could be greater. with the prop setting we are using the engine is still not running WOT @ cruise @ normal cruise altitudes; but, the prop setting we ended up using provides a good compromise between climb and cruise. Really, I'd love to have an air adjustable prop but no complaints - what we have probably keeps me from burning 6 GPH.

Never going to break the sound barrier with a Kitfox, but the view is terrific and there is sufficient time to enjoy the view.

[av8rps]

I fly a model 4 on amphib floats with an 80 hp 912 IVO IFA and generally find it to be faster than most other LSA's on wheels. On good days it will go 125 mph with WOT (which is about 5 gph). I do think the 4 could (maybe?) be faster than the newer model Kitfoxes because it is lighter and smaller.

BUT add 20 hp to the newer Kitfox models, along with the better streamlining employed on the Super Sport, and you are likely to have an even faster Kitfox. After all, the 4 through the Super Sport use the same basic wing , the largest factor in determining how fast the plane will go.

I'm convinced if one really worked at it, you can have a 140 mph Kitfox. What? Don't believe that? Google "Kitfox at Sun 100 air race". Or just read about the Model 6 history on the Kitfox factory website. You will learn my 140 mph claim is possible without even having to go crazy, as a stock tri gear Kitfox with two men can almost do it.

http://www.kitfoxaircraft.com/home/Series%206.htm

[Floog]

No surprise there AV8R. (My) 7 w/912S, Airmaster CS, and 850 tires
will do 139mph IAS @ WOT 5,400RPM @ 1,000ft.
However, I prefer 3.8 GPH +\- economy @ 105 mph, 75% power.
By running the engine @ reduced power when able, I hope to get
6,001 hours TBO. Don't know if I'll live that long! 880 hours and counting....

[av8rps]

Yeah, I do the same thing. I typically run my Kitfox 4 amphib at less power settings so my speed is more typically 95 to 100 mph in the 3 gph range. But it sure is nice to know you can easily go faster if you desire. I love that feature about my Kitfox. Many LSA's do not have that option.