Mountain Flying

[rockwoodrv9a]

I just joined the Kitfox forum. I am trying to decide what plane I want to build. One of the major concerns i have to consider is the performance at altitude. I live in Glenwood Springs CO and to go to Denver, I need to be at least 14k'. I read the specs and it shows the Kitfox has a ceiling of 16k. My questions is how is the performance at that altitude? Is there a better engine than the Rotax that would allow 14k with a full payload?

I have flown in a Kitfox years ago and enjoyed it. It was very responsive and had plenty of power - but we were at 3500' max. My friend flew his plane from Cameron Park to Idaho several times without problems, but the Rocky Mountains are quite a bit higher. Any information on how the Kitfox performs at altitude will be greatly appreciated. Also, information on how the plane travels in trips up to 500 miles. We have kids and grandkids in Boise and would like to fly to visit.

Thanks, Rockwood

[Av8r3400]

There are a few members here with 914 Rotax engines that may have the performance you need. Hopefully they will speak up...

[Dorsal]

If you put a 914 in you should be all set.

[muth]

My KITFOX IV Speedster Rotax 912UL 80hp climbs up to 14k in the Swiss alps without diffilcuties, of course no longer at high performance at this altitude.

[Monocock]

This is such a cool place to come and read each night!!

Muth - what do you do for oxygen or don't you bother? Great pics by the way.

[muth]

Just be aware of the altitude, I don't use oxygen and do not stay longer than 20 min above 10k
To cross the Swiss alps not at its highest peaks 10k is ok anyhow

[Esser]

The Rotax 914 will make 100HP at 16,000 feet. Starts to drop off there. It is a pricey engine but if you go to rotec canada they will sell you a zero timed 912 that has a brand new turbo on it for 10,000 less than a 914. It's a 912/914. Pretty much they sell 914s to the US military for the predator drone but the predator requires a different turbo and it is mounted on the opposite side. So rotec takes the 914 from austria, removes the standard turbo, and adds the predators turbo. Now they have all sorts of brand new turbos left over so they put them on their zero timed engines and sell you a 912/914 for less than a 914. WarEagle has one of these in his SS7 and I am most likely going to put one in mine. He is reporting 1800fpm climbs in it with his constant speed prop. He might pipe up soon.

[War Eagle]

Yup, if you want any "performance" in a Kitfox at 14k or above then you will need to fly with something other than a normally aspirated reciprocating engine.

I fly with the Rotax 914 which provides the full 100 hp up 16k.

For every 1000 feet increase in elevation you loose 4-5% in air density which then causes a somewhat corresponding decrease in engine output. Of course there are other factors that enter into the loss calculation (temperature, humidity etc.) but in simple terms the normally aspirated engine is producing somewhere around 50% of its rated hp at this altitude. Yes, with the 80 or 100 hp Rotax and given the time you can get your plane to that altitude and fly along just great, but you would not have additional hp for the performance part of your interest. Flying at or near gross will also impact the time and performance of your plane at that altitude.

I fly out of an airfield that is 2700 feet and I can easily see 1800fpm if I pour the coal to it. I don't often fly much above 10k so I can't tell you what you would see in the rate of climb with a 914 but the service ceiling of the 914 is around 25k.

If you are willing to put in oxygen and fly at 16k then you can cruise at 150mph. You can easily make 500 mile range in one hop but you will likely need a stop for a bio break and stretch.

The plane is easy to fly and seats two people with 150lbs baggage max. My configuratio is tricycle gear but the plane is convertable to tailwheel.

[Dave F]

Had my 582 IV Kitfox at 17,200 and still climbing slowly -- I forget what rate likely about 200 or 300 fpm .

[rockwoodrv9a]

Thanks for the info. From what it looks like, the 914 sounds like the way to go if I go with the Kitfox. I don't have a problem traveling at 10k+ and had planned to put a bottle in whatever plane I built because of the altitude here in Colorado.

I can't even imagine trying to get a 140 or a 172 from here to Denver. Im sure it has been done, but I can't see it being worth the gamble. Every year we get a few guys planting themselves in the mountains who either can't do math to figure density altitude or think they can "wish" their way through. Before flying in the mountains, I would recommend going to McCall Idaho and taking the course from Lori and her gang. It could easily save your life.

Does anyone have any additional information about the 912 - 914 turbo conversion in Canada? I will do some research - it sounds like a pretty good idea and saving the cost of a glass panel isn't bad either.

Thanks again everyone for the information. If anyone is flying in the Glenwood Springs - Aspen Eagle area, let me know. I would love to see your plane and discuss it over lunch.
Have a good evening.