float flying

[lakeflyer]

Does anyone know if a MK4 1200 speed wing will work on floats. I know it is shorter than the long wing which generally is the way to go, and can one extend a speed wing?

[Av8r3400]

Contact Av8rPS (http://www.teamkitfox.com/Forums/member.php?u=881) on this list...

[N82HB]

I have a long wing, but I have flown quite a few speedsters, and a lot of experience in a large number of float equipped airplanes.
I believe it just comes down to performance. If an airplane has excess performance than it will do well on floats.
In my opinion if you had at least the 80hp 912ul it would do fine. With a 100hp it would be fantastic.
The problem for me is, What Float? I don't think there is a good float for our size of airplane. Either they are of poor design or the wrong size for our airplanes.
The little Aerocet straight float is barely enough and as an amphib it is way too small.
Zenair has some good options, but they start to get expensive. I have experience with the smaller Zenairs on a Kitfox 1 and they did amazing, so I believe their design is good.

If you find something else that works well let me know. I am looking for reasonable performance for reasonable expense.

No. I did not forget about Full Lotus. They do not fit my idea of what would make me happy.

[avidflyer]

The standard length wing on an Avid is the same length as the Kitfox speedwing. Lots of Avids on floats. I have a set of Avid fiberglass floats that I got with a project last summer that I'm not going to be using. I started a thread on them after I got them. Some good info about them in the reply from Paul Seehaufer. Look up - Avid fiberglass floats - in the search feature and you will find the topic. I'm in Mn also. Take care, Jim Chuk

[dholly]

In defense of the Aerocets, they were designed for the lighter models with 2-stroke power. My 4-1200 w/912 is a LOT heavier than my KF3 w/ 582 was. I think they make for a very good float on the earlier models and, not great, but a reasonably priced option on a lite 4-1050 or 1200. As you say, what else is there without breaking the bank?

[DAT]

What's a good amphib float for a Series 5 with 1550 gross? What would a set that'd work go for ... ballpark?

[lakeflyer]

Hey this is some great information I was ready to buy some aerocets which would have been my first choice, now I don't think so. Aparently they don't work well on the mk4 1200 with the 912 Rotax, it would be worse with a Suburu which I believe is more weight plus two people full tanks and a little gear. I'll have to do alot more research, thanks for not letting me make a huge mistake. dan

[dholly]

Dan,

On a KF 4-1200, I would be much more concerned about EA81 engine weight than Aerocet float (straight or amphib) displacement.

Ie., if the requirement for float certification is that it provide buoyancy of 80% in excess of the maximum gross weight of that seaplane... using 1200 lbs. x 1.8 = 2160 lbs., divided by 2 = 1080 lbs. means you are only ~2% underfloated with an 1100 displacement straight float. Note: that displacement rating is for the straight, not amphib, floats. I have not personally put everything on the scale but Paul (AV8rPS)(see also: KOTM thread) who owned both said he weighed the Aerocet straight floats, rigging and hardware at 158 lbs. and amphibs at 227 lbs. That weight penalty will cost you. I spoke to Paul and three other Aerocet 1100 amphib owners, all on Kitfox 4-1200 w/ 912ul engines. Each said you must be alert at gross as the tips are easy to submerge while slow taxi and turning downwind. However, NONE said they were generally unsafe or planned on taking the amphib floats off. Paul offered comments about his KF 4-1200 amphib on the Avid forum some time ago:


I have been flying Avid Flyers and kitfoxes since the mid 80's, and
have accumulated a couple thousand hours of seaplane time in them,
with a wide variety of engines and airframes. So I hope I can help
you by sharing what I've learned in the past few decades.

Currently I am flying a Kitfox IV-1200 on aerocet amphibs. It is very
well equipped, and weighs 776 lbs on floats (650 on wheels). It is
powered by a 80 hp Rotax 912ul. (I would expext a 912 Mark IV Avid
to weigh about 30 lbs less than a Kitfox IV-1200 fwiw). That
combination makes an awesome seaplane, with performance similar to a
150 hp Supercub on straight floats. I can get off the water in 6
seconds solo, and 13-15 seconds dual. Climb rates are 1,000 fpm avg
solo, and 750 fpm avg dual. Top speed on floats is 124 mph (verified
numerous times with GPS and by flying next to other planes that
didn't believe me). Fuel burn averages 3.2 gph at 95-100 mph
(regular unleaded auto fuel- the 912ul is low compression so doesn't
need Hi octane fuel). At average fuel burn, I have a very safe 8.5
hour range. I do utilize an IVO 68" inflight adjustable 3 blade prop,
which after recent testing against a ground adjustable IVO proved a
30% reduction in takeoff time on the water, and 5-6 mph in top speed
(fwiw - a 72" three blade prop would provide even better seaplane
performance). But if I converted to either the Rotax 100 hp 912s or
the 115 hp 914 (which both weigh about the same as the 80 hp 912ul),
I would see significant improvements over my current numbers. Add
the IVO inflight to those engines and performance would be really
awesome! So I can tell you without doubt, the 912 Rotax works well on
these airplanes. Particularly when the airplane is operated as an
amphibious seaplane. In fact, I've seen a lot of various light sport
type airplanes with 912's converted to amphibs over the years. But
I've never seen one that didn't make for a good performing amphib
seaplane. I think that alone says a lot for using a 912 engine in
Light sport type aircraft like ours. We know it works.

Conventional aircraft engines as well as Subarus are just plain too
heavy for these small airplanes in my opinion. Especially if you
plan to operate them as seaplanes. A typical Subaru, Lycoming, or
Continental powered Kitfox IV-1200 will typically weigh over a
thousand pounds on floats (not necessarily even amphibs). That is
just too much weight. Not only does the airplane not perform well
because of all the added weight, but it will also have virtually no
payload. Comparatively, the lighter 912 amphib will not only
outperform them, but will also outhaul them. And I'm not just
guessing this, as I have friends that have flown the Subarus and the
aircraft engines for years, and I've had a lot of time to compare
against them.

Your [Avid] Mark IV will make a marvelous seaplane. But do all you can to
keep unnecessary weight off of it. You can realistically expect your
amphib floats to add 150-200 lbs to your aircrafts empty weight.
That absolutely kills your payload. So try to calculate your
estimated empty weight before you get too far along...that will help
you to resist the temptation of adding luxuries you really don't
need, or want on a seaplane.

Just my two cents worth.

Paul Seehafer
Wisconsin

[lakeflyer]

Well, I'm going to skip buying the kitfox with a subaru that I found, it sounded so nice. I was wondering about the weight issue. Looks like I should keep my sites on the KF 4-1200 with the rotax 912. I wish there were more around for sale. I am greatful for all the advice and help, thanks dan

[dholly]

If you're going to float a 4-1200, general consensus says a light frame with 80 or 100 hp 912 is the best configuration possible. Or, if you can tolerate a 2-stroke, you might even consider re-powering a lightweight 4-1200 w/582 with one of the big Rotax 670 90hp motors. At the very least, IMHO, either combo will give you the option to use the Aerocet amphibs. If you take those out of consideration in favor of a higher displacement float, your amphib float options become extremely limited, baggage capacity reduced and your cost to equip skyrockets unless you want to pull several thousand rivets yourself. Unfortunately for you, since that combo also arguably makes for the near perfect KF4 on wheel gear, not too many are given up by their owners voluntarily, last long on the market or fail to command a premium over similarly equipped Sube powered model 4's. BTW, that award-winning 4-1200 w/ Sube FWF listed on BS right now was originally on Aerocet amphib floats, but I see the 2nd owner swapped them out for Full Lotus straight floats. My guess is the heavier nose and overall empty weight simply proved too much for the Aerocets just as Paul said.

[N82HB]

It is important to know that the number associated with a float is just a name and may not equal displacement. Wipline has typically named their floats for the highest gross weight they can support. Aerocet has used a rounded number closest to displacement, but those 1100'sbig are old floats and may not follmay be required.ow this. A little research.
The best choice right now, I believe is the Zenair line. But, they can get expensive quick.
They would have a nice float for a 5.

[Dave F]

Aerocet 1100s Amphibs
I have these and cthey work well although unfloated.
They were originally a 1100 displacement straight float.
The Amphib gear added weight so lets call it a 1000 to 1050 displacement float.
Hydrodymanically a great float on the step and very Aerodynamic.
I lose only a few MPH goin from wheels to floats.
Cruise with 582 85-86 mph on amphibs.
912s with these floats if nuilt light is a rocket..........and enough power to overcome the loss of buoyancy of this float.
Down wind turns in stiff winds will put your outside float unwater - can be intimidating.

http://www.youtube.com/watch?v=GMoPc_cvxS4


http://www.youtube.com/watch?v=VpSAiFsJJj4

Now you want a very popular float with many planes like Supercubs guys
http://www.clamarfloats.com/

He has 1400 displament amphib now and they were actually modeled off of my Aerocet 1100s they ( inflated by about 35% ) Computers are wonderful.

He is located 7 mile from my strip and you ever want to see them.