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Thread: Model 5 Continental Performance

  1. #21

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    Jun 2017
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    Fort Worth, TX
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    Default Re: Model 5 Continental Performance

    Quote Originally Posted by av8rps View Post
    I fly a 80 hp 912 ul on amphib floats with an IVO IFA prop, and it works great. In many regards it is a little hotrod. But it's under 800 lbs on the floats. Keeping the weight down is a huge advantage with the smaller wing area of the Kitfox, which is the primary reason the 4 is easier to make work on floats.

    However, I can't see any reason that an 0-200 Model 5 won't work as a floatplane. It will probably never perform like the 100 hp 912 model (much lighter) but it should still make for a fun floatplane.

    But, 2350 floats are way too large for a Kitfox. 2350's are for a Husky or Glastar. 2350's would be large even for a 150 hp SuperCub. With a Kitfox in the 850 range empty weight (on wheels) I would suggest a 1550 to 1650 lb float (buoyancy being typically higher than number on float). Paul L's IO-240 Kitfox flew on Murphy 1800 amphibs if I remember correctly. And those were probably a bit larger than he really needed, but he did get them to work.

    With that said, once you have properly sized floats on the plane, you should set the prop pitch so that you know you will overspeed the engine with wide open throttle when straight and level. Yes, it's going to be set really flat. And yes, you are going to lose cruise speed. But it's a floatplane so you won't really care with all the fun you are going to be having

    You need all the takeoff power you can get. Floatplanes take a lot more power than a landplane. They have to plow through the water to get on the step, and then have to break the suction of the water in order to leave the surface. Land planes have none of that to deal with, so getting a floatplane set up properly can be difficult by comparison. But I can assure you after waterflying for more than 3 decades, it's worth the effort!
    Av8rps, thank you for that information and renewed motivation. Yes, I can easily sacrifice speed with floats. Many, many apologies as my Lotus floats are 1450’s; not 2350’s as I mistakenly wrote. Only a 900 lb error! A previous owner said he couldn’t get it on step and thought he had the right help with rigging. I’m not totally convinced my heavier Continental O-200 is performing as it should be yet but I’m playing with prop setting to see if adjusting it helps. I’m not an A&P and I’m fairly new to plane ownership - 1 year. I’ve had a conversation with Kitfox and the nice lady I chatted with did say the Rotax 912 engine weighs in 80 lbs lighter and if I could start over knowing what I know now, that would be my engine for that very reason. If I can get my plane safely in the air with no amphibious gear, I’d be a very happy Kitfox camper!

  2. #22
    Senior Member Maverick's Avatar
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    Default Re: Model 5 Continental Performance

    My last KF5 had an 0200-A with a 70" three blade Ivo-Prop. I set the pitch according to the RPM. Initially, I had the pitch too high and was getting 2450 RPM and 125 MPH. I flattened the prop so max RPM was 2750. My speed came down to 115 but my climb improved significantly. I generally cruised at 2550 RPM @ 110 MPH. My flying buddies were running 912ULS and could out-climb and out-run me so with this build, I'm using the 912ULS.

  3. #23
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    Jul 2011
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    milwaukee wi
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    Default Re: Model 5 Continental Performance

    To get more power from an O-200A, install pistons from the O-200D. They raise compression from 7:1 to 8.5:1, you will get a real 100hp.

  4. #24

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    Fort Worth, TX
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    Default Re: Model 5 Continental Performance

    Quote Originally Posted by Maverick View Post
    My last KF5 had an 0200-A with a 70" three blade Ivo-Prop. I set the pitch according to the RPM. Initially, I had the pitch too high and was getting 2450 RPM and 125 MPH. I flattened the prop so max RPM was 2750. My speed came down to 115 but my climb improved significantly. I generally cruised at 2550 RPM @ 110 MPH. My flying buddies were running 912ULS and could out-climb and out-run me so with this build, I'm using the 912ULS.
    Hi, Maverick. I seem to be following your path and right now I’v got too much prop pitch. I’ll back it off some by reducing pitch to get better numbers. Your experience with O-200 vs 912ULS makes me think that if I am not successful getting off the water like the previous owner then I may have to make a drastic change and consider swapping engines and/or floats.

  5. #25

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    Jun 2017
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    Fort Worth, TX
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    Default Re: Model 5 Continental Performance

    Quote Originally Posted by mr bill View Post
    To get more power from an O-200A, install pistons from the O-200D. They raise compression from 7:1 to 8.5:1, you will get a real 100hp.
    Thanks, Mr Bill. The previous owner said the experimental engine was rebuilt at a higher hp than stock so the oil pressure runs a bit high. My engine records indicate that Dons Dream Machine did the rebuild with 40327 pistons. I’ve tried to confirm if these pistons are the higher compression pistons but no luck yet. I plan to call DDMs to see whay they say. Have a great day.

  6. #26
    Senior Member Maverick's Avatar
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    Default Re: Model 5 Continental Performance

    Steve,
    Were you to swap engines, remember that the wings are swept forward one degree for most non-rotax engines and address the W&B accordingly.

  7. #27
    Senior Member av8rps's Avatar
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    Default Re: Model 5 Continental Performance

    Hey Steve,

    Glad to know those are 1450's rather than 2350's. That should be a good float for your Kitfox. Full lotus floats usually have lots of buoyancy for their rated sizes.

    Yes, the 912 will probably do a better job being so much lighter. But with an 858 pound 0200 powered plane on wheels, that is not too bad. I've seen a lot of newer Kitfoxes with the 912 that are in the 850 range. I have a friend that has a Cessna 120 on straight floats with an 0-200 and it performs quite well. And that has got to be heavier than your Kitfox. So I believe if you just get that 0-200 to wind up like it should that it might surprise you. Plus, there are so many mods for the 0-200 to make more horsepower that you will have a lot of options should you find yoursel needing more performance.

    I'm looking forward to hearing your results with some prop tweaking.

  8. #28

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    Jun 2017
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    Fort Worth, TX
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    Default Re: Model 5 Continental Performance

    Quote Originally Posted by Maverick View Post
    Steve,
    Were you to swap engines, remember that the wings are swept forward one degree for most non-rotax engines and address the W&B accordingly.
    I didn’t know that but good information to put in my back pocket for planning purposes. Thanks.

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