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Thread: Anyone running Zenair (or other) Amphib's? Thoughts?

  1. #1

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    Default Anyone running Zenair (or other) Amphib's? Thoughts?

    Kicking around the idea of a set of Zenair 1450 amphib's for my Model 5. Although, I wonder if my plane would be a little under-floated with these, and all loaded up with gear. I'd rather be a little over-floated than under-floated. Would appreciate any feedback from other Kitfox 5+ owners who have (or have had) these floats on their plane. Would also appreciate any info on other amphib float options that might work out well for these 1,550 gross planes.

  2. #2
    Senior Member av8rps's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    The Zenair 1450 amphibs are a good float, especially for the money. They work well on Model 5 and up Kitfoxes, Highlanders, and Rans airplanes. I don't think you would be "underfloated" as they seem to have a lot of buoyancy. I've had a lot of friends that have used them on a variety of LSA planes over the years and liked them. They have excellent off the water performance for an amphib.

    Probably the biggest downside of the float is that the landing gear has no suspension. They use a large main gear tire, so that provides the suspension. And overall that works pretty well. But I'd stay off rough grass strips with them as you can cause a lot of fatigue on the float itself where the gear attaches. Of course, most amphib floats are that way. Face it, you are trying to do a lot with an amphibious float. Due to weight limitations landing gears on floats just can't be built as strong as a standard aircraft landing gear. So they go for the best overall compromise.

    Another downside of the Zenair float is that due to the round top shape they do not have storage compartments. I know some guys have modified them for compartments, but I personally think that compromises the strength of the float too much. Think of a round soda can. Once you dent the side the strength is gone. It's kind of like that. So I personally would not recommend modifying them for storage. And frankly, newer model Kitfoxes have the ability to have a large baggage area so I would just optimize that.

    With all that said, I personally prefer the CZ 1300 (aka CZ 1500) Czech built amphib float. They are essentially a scaled down version of a Wipaire 2100 amphib. They are a nice handling aluminum float, have probably the best landing gear set up for a LSA size float, are still reasonably light, and have moderate sized storage compartments. Unfortunately they can be hard to find as there weren't many made. Rumor has it they are building them again, but I can't verify that. Ken Smith at www.Harborsportaviation.com currently has 2 sets for sale, but those are the only ones I know of that are currently available. Expect to pay upwards of 25k for a nice set. Pricier than the Zenair, but already built, and a really great float imho.

    My second choice would be the Clamar 1400 amphib. I like the fact that the gear is electric actuated making float changeover much easier, and that being fibreglass they are less prone to leaking. But they are going to be probably mid 35k-40k range by the time you get them on the plane.

    I would recommend you check out Ken's site. He is by far the leading expert on LSA floats and his site contains a lot of good info regarding floats for aircraft like your Kitfox.

    Paul

  3. #3
    Senior Member Eric Page's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  4. #4
    Senior Member av8rps's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Good find Eric. But while the 1200 straight float would be awesome for a 650 lb ('ish) EW model 4 or a heavy 2 or 3, the Model 5 and up will need the larger float capable of around 1450-1500 lbs of buoyancy.

    I will say to any of you Model 4 guys wanting a super high performance float plane (and don't need or want amphibs), those 1200's with a 912 (and especially with a Zipper kit) make for a GREAT little float plane. And the price is right. Especially already assembled, as building floats can be as big of a job as building the plane sometimes.

    Oh, and worth mentioning for any of you that aren't aware: Float sizes are listed all over the place, so can easily be confusing, and sometimes downright deceiving. Zenair makes it simple by identifying their floats with a number representing the approximate gross weight of the aircraft they will handle. So a 1200 will float approximately a 1200 pound gross weight aircraft, a 1450 therefore a 1450 pound aircraft, etc.

    But that is not how floats are typically rated. Here is how the FAA wants floats rated;

    Sec. 23.751 — Main float buoyancy.

    (a) Each main float must have—(1) A buoyancy of 80 percent in excess of the buoyancy required by that float to support its portion of the maximum weight of the seaplane or amphibian in fresh water; and
    (2) Enough watertight compartments to provide reasonable assurance that the seaplane or amphibian will stay afloat without capsizing if any two compartments of any main float are flooded.
    (b) Each main float must contain at least four watertight compartments approximately equal in volume.
    [Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23–45, 58 FR 42165, Aug. 6, 1993]

    So now that you are totally confused, let's look at how I interpret that. Let's first determine what a 1430 pound aircraft needs for a float size according to the FAA. So take the 1,430 pound gross aircraft weight and divide it by 2 to arrive at the weight each float needs to support, That number is 715 lbs. Now add 80% to the 715 for the excess required, or 572 pounds, for a total of 1,287 pounds. That 1,287 lbs is the FAA required float buoyancy for EACH float.

    So those Zenair 1200's should work, only being 87 pounds smaller than needed, right? Wrong. Because Zenair identifies their floats by the aircraft's gross weight rather than the FAA's method, we don't know the actual real life buoyancy of the float. And guess what. based on real world experiences with Zenair 1200's we know they are "under-floated" on most 1430 pound airplanes, which can make them dangerous and poor performing due to sitting too deep in the water, having virtually no excess "Reserve buoyancy". However, they work very well on aircraft in the 1200 lb range.

    So lets now look at those Czech built CZ 1300's I like. Well, this is where it gets confusing, as that 1300 rating on that float appears to be done like the FAA requires. So being that each float will support 1,300 pounds (more than the 1,287 pounds required for a 1430 aircraft) they are about perfect for a 1450-1500 pound gross weight aircraft. And based on all the airplanes I have seen the CZ 1300's installed on, the float based on Zenith's method of rating float sizes, I'd put them at 1400-1500 gross weight aircraft. Not too big and not too small. Perfect from my point of view. And I say that after flying them a bunch too (Highlanders and Rans S-7's mostly).

    Sorry for the book here, but I said all that to try and help any of you that are contemplating spending your hard earned cash on one of the coolest accessories you can add to an airplane. Sizing floats properly can be very confusing, not to mention potentially being a very expensive and frustrating experiment if done wrong. But if done correctly you will have equipped your favorite toy with a super cool set of floats that allows you to go places many can only dream about.

    And if I have totally confused you by now, and you just want the quick and easy way to know what floats will work on your plane, visit my friend Ken's website at www.harborsportaviation.com, and click on the "More information" tab where you can read Ken's views on some of the most popular LSA floats. He knows his stuff guys. And his experience is unsurpassed in the LSA world of floatplanes. And I think you will find his views reflect much of what I tried to explain above.

    Good luck with choosing the right float!

    Paul
    IMG_0814.jpg
    (My Model 4 amphib at home on a beautiful sunny day in central Wisconsin. An amazing float plane)

  5. #5
    Senior Member JoeRuscito's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Might be a bit late reply. I have a set of Clamar 1400 amphibs on my S7 supersport 912is, whirlwind (ground adjustable) prop. They perform really well, although I don't have a ton to compare to. I'm getting roughly a 15-18 sec take off on average when I'm single pilot and about 30 sec when at gross (1550 lbs). I've flown them in all kinds of conditions (about 80 hours), beached, boat ramped, docked, landed on rougher grass runways, they seem to take it all well. Also have had some hard landings and so far so good. They are pretty sticky on glassy water but do eventually release. I do not have a ventral fin and have noticed that I have slight yaw instability, that of course was not present on wheels. Otherwise the plane feels about the same as it does on wheels, just a bit slower. I don't feel under-floated, but again little experience. Step turns are no issue. I can also have two ~180 lbs guys stand on the very aft or very bow (one on each float) without feeling like it will tip over.

    One other thing to point out, I was originally building a pair of Zenairs. If you go this route, GET THE PREDRILLED KIT, I did not. I got about 2/3 through one float and had enough. And I love building. The floats seemed to be more work than the whole plane, as others have said. At this point I'm happy I bought and sold the zenair kit.

    Specs on my aircraft:
    Grove gear and 26 airstreaks: 864 lbs 10.81 CG. Cruise speed ~104 mph with the prop pitched slightly favoring climb. Stall speed 38 mph IAS full flaps (Vgs installed on wing and tail)

    Clamar floats installed: 1060 lbs 9.53 CG. Cruise speed ~96 mph with the same prop pitch as above. Stall speed 45 mph IAS full flaps.

    Feel free to PM for my number if you want more detail.

    unnamed.jpgunnamed (14).jpgunnamed (15).jpg

  6. #6
    Senior Member efwd's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Good Lord. That first pic is like a dream. That has to be the best.
    Eddie Forward
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  7. #7
    Administrator DesertFox4's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Beautiful Kitfox Joe. Looks great on the Clamar floats.


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  8. #8
    patrick.hvac's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Joe that plane is beautiful!
    Do you have any information posted about the setup of the Clamars on your plane?
    Placement and rigging? That looks like a great option for the Model-7.
    🇨🇦CANADA
    Flying | SS7 | G3X | Edge 912

  9. #9
    Senior Member av8rps's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    Joe, I agree with the others...what a great Kitfox floatplane! Beautiful.

    And thanks for posting the performance and W&B specs. That really helps others considering floats.

    I'm not aware of the actual buoyancy of the Clamar 1400's, but I think they work well on even the heaviest LSA type aircraft. It is a great float.

    Paul

  10. #10
    Senior Member JoeRuscito's Avatar
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    Default Re: Anyone running Zenair (or other) Amphib's? Thoughts?

    I haven't posted anywhere, mostly because it would be a long novel. Anyone who is in need of, or wants to hear the whole dissertation is welcome to PM/get my number and I will do so verbally!

    That said here is the summary, this is all highly dependent on initial CG and empty weight.

    Three variables to deal with: Height above the floats, angle of attack, and fwd aft position. The first two while somewhat related are easier to determine, but do have some personal preference mixed in. I went with 5 degrees nose up relative to the bottom of the fuselage to the float top (on ground not floating). When the floats are floating this gives me a little more like 7-8 degrees AOA on the wing. As for height, I wanted to be a little higher to protect the prop and fuselage from spray. Roughly 23.5 inches measured at the rear attach point to the top of the float (perpendicular to the float).

    Now the more complex variable took two attempts. The gear was weighed after being removed and the empty CG of the airplane was calculated to be 9.84 in. Note: In level flight. This is different then the CG when floating, and that is dependent on the variables above as well as your vertical CG position, which very few of us calculate. There is a balance between flight performance/cg and float performance/floating CG.

    The first position the fuselage was too far back on the floats. And while it floated fine and wasn't unstable it took significantly longer to get off the water, close to 60 sec at gross! In this case the CG was only about 2 in FWD of the step (when on level ground).

    I ended up moving the fuselage 5 in forward relative to the floats, which put my in flight empty CG (without wheels) almost directly over the CG or center of balance on the floats. Said another way, the CG is unchanged when installing the floats.

    Happy to discuss more, even after doing it, it's easy to get all the variables jumbled. All in all you don't want it too far forward or too far aft, but somewhere right in the middle. Ha!

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