Cruise Speed

[Rodney]

I started thinking - ok - daydreaming ( thinking can be seriously dangerous in my case ) about how nice it would be to have a little bigger engine so I could cruise a little faster into those 30 mph headwinds that often seem to find me.

So, I went to the Kitfix website and found this information about the SS7

"Most noteworthy is a variety of engine system enhancements that have resulted in an airplane that can cruise at over 150 mph, fly 700 miles non-stop, and heft a useful load of 700 pounds."

Can we really cruise at 150 mph??? Anybody doing that? Is this true airspeed or indicated? I'd like to hear of anyone that has really done 150 tas or ias.

If a Kitfox can really go that fast safely,it would be awesome.

Rodney

[DesertFox4]

Rodney, the only place I saw these numbers used was with SkyStar when they put a 914 turbo on the 7 and a Hoffman constant speed prop. They were using altitudes above 18,000 feet and true air speeds. If I recall right, they did attain these numbers. Not many IFR equipped Kitfox to be at those altitudes but bragging rights I guess.

Now John McBean gets some pretty impressive cross country speeds and altitudes with his 7SS and 914 turbo with a constant speed prop. and oxygen on board but he doesn't fly in the flight levels, at least yet.

[jiott]

Never exceed speed is specified as 140 mph?

[DesertFox4]

The 150 mph claim was using TAS at high altitude ( above 18,000'), as I recall. That would keep them easily below the indicated never exceed speed of 140 mph.

[Rodney]

Ya Jiott. That's what I thought till I read the KF website. Thought I must be missing something here. (Not unusual)

DF4 - that is really interesting info. You sure know some interesting history when it comes to the Kitfox.

Ok - so now JM is hanging a 180 hp Titan 340X on a KF. Surely it can go past 150 in level flight.

So that brings me to the next question. Structurely - what is it on the KF that limits the Vne to 140? Or, is that the real limit?

Rodney

[jiott]

J. McBean can correct me if I am wrong, but I believe that the 140 mph Vne was the highest speed tested at the time the Kitfox was going thru the certifications for SLSA, probably because that was all the power available for testing at that time. It may or may not be capable of more than that, but if you exceed 140 you are a test pilot on your own.

[Av8r3400]

The model IV-1200 has a VNE of 140.

Without wanting to offend, seriously if you want to go faster than 120 or at most 130, you really should consider something other than a Kitfox. There are airplanes that handle the speed you are looking for far better than a Kitfox. The Kitfox is a STOL design, not a high speed cruiser like an RV.

[airlina]

The first time you fly your Kitfox anywhere near the redline of 140 , you will make a note to self , DON"T DO THAT AGAIN! Bruce N199CL

[Dorsal]

BTW, I belive VNE (as it relates to flutter) is a function of true airspeed not indicated

[av8rps]

I don't doubt you could get a Kitfox with the Riblett airfoil to go 150, especially at altitude. I seem to recall the factory 914 demonstrator going 151 mph average at altitudes as high as 21k. But even at lower altitudes all cleaned up even with just a 912s they can scoot right along. Remember when they ran a factory 912s demo in the sun 100 air race? Even with two guys in a tri gear and only running a bit higher than sea level it averaged 139 mph. Knowing that, 150 mph is for sure feasible. A bigger engine for sure would help if you can keep the Kitfox light, but aerodynamic clean ups will probably get you there even without the big engine.

BUT, I agree with the others saying its not really designed for that. I mistakenly once hit 155 mph in my Kitfox 4 on floats (!!), and while it concerned me being over VNE specs, it was still accelerating in that long shallow dive I was in trying to catch up to my friends ahead of me (for the record I passed them like they were standing still...the seaplane community still marvels at my hotrod Kitfox ). The new wing is nothing like the old wing. My 80 hp Model 4 on floats will go 125 mph at max cruise power straight and level, so again, these things can scoot if set up well.

So while I am positive you can get a Kitfox to do those numbers, if you own one you are likely to discover what we all have... no matter what your cruise speed is, the Kitfox is an absolute blast to fly, so you don't mind if it takes longer to get somewhere compared to faster, but typically less fun cruisers. It's not the destination, it's the adventure...