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Thread: Would like Info On IFA IVOPROP

  1. #31
    Senior Member Slyfox's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    not that it matters but I put mine up for fine and down for course.

  2. #32
    Senior Member kmach's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    Good stuff ! I was planning on putting the switch left of my throttle, so you both have confirmed this idea.

    Are you guys running spinners ?

    I am going to call UHS next week. I don't think the UHS (9P) I have for the GA IVO is going to work with the IFA, the GA spinner mounts under the 3/8" prop bolt heads with a cutout for the jam nut.

    I would like to set the prop up once, with the spinner and possibly some limitation washers, this might be hard to do but worth a try.

    It's hard to plan without the hardware in your hands!
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  3. #33
    Senior Member av8rps's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    Here's something I shared on another forum recently when someone asked a similar question;

    Last night while flying my Kitfox (on Aerocet amphib floats) in really nice calm skies I did a test to see what the real gain is for top speed using my IVO in flight adjustable prop verses if it were a ground adjustable version (to do the comparison I just moved the prop switch to change the pitch, "pretending" as if I had adjusted the prop on the ground with a wrench and a prop angle gauge).

    Here are my results;

    Flying straight and level with wide open throttle (912ul - all 81 ponies)

    - At 5800 max rpm I was able to go 119 mph.

    - Leaving the prop set for a max rpm of 5800, I pulled the throttle back to 5500 rpm (max continuous power for a 912) and my top speed was now 114 mph.

    - Putting the throttle back to wide open again, I increased the pitch so I could only get 5500 rpm, which provided the highest speed tested...124 mph.

    - Moving the electric prop to maximum pitch while keeping the throttle still wide open, giving me 5275 rpm my top speed dropped to 116 mph.

    So, I proved to myself last night that the inflight adjustable prop does in fact make my Kitfox faster. BUT, if I set a ground adjustable version to a max of 5500 rpm, it would fly just as fast (assuming the blade style and dimensions were the same for both props). Of course, then I would lose some takeoff and climb performance, so a better setting for water ops or STOL work might be a max rpm setting of 5800 rpm straight and level. So I could expect to lose around 10 mph in top speed when comparing the IFA to a ground adjust version.

    In addition to the improved top speed, takeoff, and climb, another thing I really like to do with mine is to fly around at 4,000 rpm at 80-85 mph with a lot of pitch. It makes for a really quiet and smooth pleasure flight that doesn't burn much fuel.

    So for now, I'll be keeping my IFA prop. I shared this information so I could let everyone know what the real gains are with an IFA prop.

  4. #34
    Senior Member Dorsal's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    Nice write up, confirms my thoughts on IFA. What surprises me most is that you manage to get 124 mph with 80 hp and floats, thats about what I get with a cruise pitched prop and a 912S. Very impressive as I had thought floats would have significantly more impact on top speed.
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

  5. #35
    Senior Member SkyPirate's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    Back in the 1900's ,..thinking 97,..might be off a year or so ,. I was playing with a set of flat bottom fiberglass floats,..that were rated for around 700 lbs ,.so I put them onto a 3/4 wing sprint,.. top speed prior to putting the floats on was 65 mph,.after I put the floats on my speed indicated 70 mph,..this is with a 447 fix pitch,.
    the floats,..I cant remember the manufacturer ,..were round top flat bottom with a 2 1/2 " step,..the had a single top square tube mounting system that was mounted on top of the float from the step forward about 5',..I didnt like the way the floats,.."flopped" and twisted when taking off and landing so I added some braces on a 45 degree to the inside ,..or between each float,..so ,..my point ,.I had added even more to the drag of the orginal set up.
    I didnt get too indept as to finding out why I gained speed with the floats,..I'm sure the added weight ,..but also the angle of the bottom of the floats in relation to flight had something to do with it,..

    So ,..the shape of a set of floats? the angle of incedence in relation to flight? and the weight? and of course the drag of the system you choose to mount the floats,..evidently I got lucky in my set up because I was able to gain speed even though the drag was increased.
    the flat bottom floats flew great ,..the problems with them ..flat water ,..you had to basically go out to where you wanted to seperate from the water and spin around a couple times,..back track down wind and then head towards the waves you had made to get seperation,..
    and I did not land or take off in any swells over a foot,..the flat bottom floats will literally beat the crap out of you at speed
    I would NOT recommend flat bottom floats for a kitfox or anything that hit's or leaves the water in excess of 40 mph

    sorry for getting way off topic ,..just a little piece of float info
    Last edited by SkyPirate; 09-22-2011 at 07:39 AM.

  6. #36
    Senior Member av8rps's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    Quote Originally Posted by Dorsal View Post
    Nice write up, confirms my thoughts on IFA. What surprises me most is that you manage to get 124 mph with 80 hp and floats, thats about what I get with a cruise pitched prop and a 912S. Very impressive as I had thought floats would have significantly more impact on top speed.
    Yeah, my little Ol' 80 hp Model IV is a real hotrod. It totally irritates my friends that fly LSA type seaplanes with me because they typically struggle with keeping up (Rans S7, Rans S6, Highlander, Zenair 701, etc). On average my top speed is 20 mph faster than those planes, and I am running an 80 hp 912 vs their 100 hp 912s's. But I also am running that IVO IFA when they are typically running Warp ground adjustables.

    And yes, for anyone wondering...I have verified my airspeed accuracy. In fact I've done so countless times. It is accurate within 1-2 mph.

    And for anyone thinking a Kitfox might be faster on floats than on wheels, it flies about 6-7 mph faster when on its regular gear with 8.00 - 6 tires. The Aerocet floats are pretty low drag for a float, but they still are 14 ft long, two plus feet around, use gobs of high drag bracing cables and attaching struts, and weigh more than 200 pounds. That all makes for a lot of added drag that my little ol' 80 hp Kitfox has to push (and lift) through the air. I marvel at the fact that it does so well with that, and consequently love the performance of my Kitfox amphib.

    Oh yeah, I forgot to mention that with just me and 2 hours of fuel in near perfect conditions I can get my Kitfox off the water in 6 to 8 seconds, and 13-15 seconds with 400 lbs cabin load. If you know much about seaplanes, that is equally as amazing as my top speeds.

    And while it is all pretty amazing, we really shouldn't be surprised that it can compete with the speed performance of a newer model Kitfox. The wings are the exact same for both airplanes, yet the newer Kitfox is likely to weigh on wheels what my Kitfox weighs on amphibs (776 lbs). So wing loading is the same. And then when you consider how much smaller in size the IV is than the newer Kitfox, I suppose it is possible that a Model IV on floats could have similar drag to the larger Kitfox on wheels, especially a nosewheel version without pants. Throw in the fact that I use an IFA IVO, and even though I only have 80 hp, it suddenly starts to make more sense. At least that's how I see it.

    And honestly, I'm not completely sure why it flies like it does. But I sure do enjoy it! It is an awesome airplane, and is even more awesome as a seaplane. I couldn't be happier with it (but I admit that one day just for grins I may put that 100 hp 912 I have in it, just to see what it will do) .

    (One last note I thought of as I was ending my novel)

    I have now played with 3 different IVO props;

    A UL 3 blade "High pitch" that was only 65" in diameter and wouldn't let me get the rpm any higher than 5100 rpm for takeoff with the electric IFA motor.

    A 68" UL 3 blade that would allow the motor to flatten the pitch for takeoff to 5800+ rpm.

    And a 72" 3 blade UL that will let the motor flatten the blade so I could get 5750-5800 rpm for takeoff.

    Results;

    The 65" diameter blade actually makes the airplane fly the fastest, but takeoff and climb performance suffered (due to being unable to get the blade flat enough to get max rpm, or the blade length, or both?)

    The 68" blade is the best all around for takeoff, climb, and cruise, and is the prop I feel works best overall.

    The 72" gives a much better takeoff and climb, and better braking on descent, but drops the top speed by about 6 mph.


    What I believe I learned by playing around with these various props is that we are many times running too long of a prop on the smaller hp 912. A smaller diameter prop is likely to provide better overall performance.

    And it's not just the IVO. If you read comments some of have made about KIEV's on the 80hp vs the 100hp 912, it appears they may have experienced the same thing?

    But of course, this is all subject to testing accuracy. So take it for what it's worth...and remember that it didn't cost you anything.
    Last edited by av8rps; 09-22-2011 at 03:44 PM.

  7. #37
    Senior Member Slyfox's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    I agree, when I had the 912ul I also had the Ivo and I found that going to the size you suggested gave me the best all around performance. IVO in my opinion can't be beat.

  8. #38
    Senior Member av8rps's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    So I'm curious, on the 100 hp 912 does the 72" work better? I would think it might, but I don't have the 100 hp on my Kitfox to test. Although I have thought about taking the Sensenich off my Highlander and trying my 72" IVO on that as it has a 100 on it. But, comparing the Highlander and the Kitfox would really be an apples and oranges comparison.

  9. #39
    Senior Member av8rps's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    Quote Originally Posted by SkyPirate View Post
    Back in the 1900's ,..thinking 97,..might be off a year or so ,. I was playing with a set of flat bottom fiberglass floats,..that were rated for around 700 lbs ,.so I put them onto a 3/4 wing sprint,.. top speed prior to putting the floats on was 65 mph,.after I put the floats on my speed indicated 70 mph,..snip snip
    Interesting information for sure. It is basically unheard of for any airplane to gain speed by adding floats. Traditionally the best you can hope for is to not lose any speed, but that is also rare. Early, very lightweight Avid Flyers were known for not losing speed with the addition of floats. But as the Avid Flyer's evolved, and got heavier, they too lost speed.

    And I couldn't agree more with your comment about flat bottoms on floats. I also own a LA-4 Lake Amphibian, and it has a pretty flat hull compared to the later "Renegade" model. And let me tell you, rough water and boat wakes can be a real handful. There's nothing worse than not being up to flying speed and getting tossed into the air when you are in an airplane that can quickly develop an uncontrollable porposing condition. The deeper V they put on later Lakes solved that problem 99%. So even if a flying boat vs a float, flat bottoms are not the answer.

  10. #40
    Senior Member Slyfox's Avatar
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    Default Re: Would like Info On IFA IVOPROP

    I believe mine is a 70" medium. I had the patriot at first on it but would cavitate on take off If I put the power to it too much. I love the medium for the 100.

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