Float choice

[aktango58]

Here is my suggestion: When you get comfortable, try some different methods to get the floats out of the water.

Sometimes they will lift better one float at a time, sometimes pulling flaps and stick back at the same time...

Also, angle of incidence between the wing and float make a big difference, and can (and has) been wrong on factory floats. You may need to adjust the distance between the rear float fitting and the rear deck fitting to get better performance.

What I am saying is DO NOT GIVE UP ON THEM until you really give them a chance!

Any float is better than no floats

 

[Olibuilt]

Any float is better than no floats

That's what I tought. Just arriving trying my skis on the water. I don't think they would float for long....

 

[skywagon8a]

I agree with aktango58- I used to have to give a little pull to break free of the water in my 185. Then I shortened the rear float strut 3/4" and now it just flies off. There was no other noticeable change. I think that you will be very satisfied with those floats. Give them a good try. Get some knowledgeable float person to help set up the rigging so that the angles are all correct.

 

[cubdriver2]

So, some questions for you float experts, I was told that 4 degrees is about the max angle between the wing and the floats.

1- What would be the max angle between the wing and floats for getting off as quick as possible and not worried about cruise and how much will it effect stall speed

2- Whats a good all round angle for decent off the water and still have some travel speed.

Glenn

 

[skywagon8a]

As a general rule of thumb 4 degrees is a good number. A greater number will increase drag in flight and to a certain extent while accelerating for takeoff. There are a lot of variables such as wing airfoil, engine power, float size and shape etc. I am trying 3 degrees on my Backcountry 18 on EDO 2000s. This to reduce a little drag in flight. My wings have flaps which are twice as long as the stock Super Cub so I hope that the increased available lift will offset the lower angle. Time will tell. I have made the top rear strut fitting so that I can change the strut length. I haven't flown it yet.

 

[Olibuilt]

I was looking for infos for rigging them good under my plane. The plane is built just like a Super Cub.

Where can I find good instructions to rig a Super Cub ? ? ?

What height should I look for if I plan muying a 90'' prop??

I have this plan to start with. What do you think.

 

[Wannabe Cubdriver]

Oilbuilt,

I saw a set of floats for you today on a trailer heading west on the 401 between Kingston and Belleville.

 

[mvivion]

I would start with very little nose down angle on the floats. It's always easier to cut struts off than extend them. The Husky uses 1 degree, and that is near perfect on that airplane. Closer to 1 will fly faster, and get off the water quicker in some cases. But, that does depend somewhat on the design of the float bottom. Experience will tell. The C 180 launches better with one bolt hole cut off the aft struts. Can't recall who told me that, though.

MTV

 

[skywagon8a]

Olibuilt-Your drawing assumes that the top of the float is parallel to the keel which is true on most floats. The keel angle to the water is for the optimum (sweet spot) planning angle, which is what you are looking for. The drawing shows 3 degrees to which is added aprox. 1 degree for the angle of incidence of the wing to the reference line. This equals the 4 degrees which is referred to in the above post. Most float installations are in this range. The 1 degree that MTV refers to seems unusually flat. Does MTV know what the angle is between the keel and the wing chord line on the Husky?

Your drawing shows the step location as being plumb to the 50% chord line. The following quote is from Dave Thurston's book 'Design for Flying', "To provide stable trim for planning, the hull step should be on a line running approximately 10 degrees aft from a keel perpendicular through the gross weight center of gravity." It could be that this is just two ways to arrive at the same answer. You should check both ways.

Do you have the spreader bars for these floats? The distance between the keels on EDO 2000s is 85". The angle of the struts from the floats to the fuselage is aprox. 45 degrees.

That height should be OK for a 90" prop.

 

[louisC]

Looking at those side walls that are near vertical, and looks so huge on the front part, i would be scared with crosswind. Like the weathervane and the arrow, the farther aft the point of side pressure is placed and the larger its size, the greater the airplane’s directional stability. On the contrary, your floats will bring your side pressure center in front of your center of gravity. That gives nasty reaction with side gust of wind: the nose, instead of turning toward the wind, goes on the other direction. Slipping such equipped airplanes also gives "interesting" reactions when you go out of the slip. Like some beavers when they are equipped with small stab fins instead of the big one.

I strongly suggest to study the possibility of putting supplementary fin like wipline does for Husky, 172, 206, caravan, beaver, Otter, etc etc etc . In fact, there is almost only the Cub that are not equipped with supplementary fin on wipline floats. And for my cub, the rare occasion when i have to land or take-off crosswind, i would take a little more aft side load of the wind.

When i have put my Helio on floats, it was quite marginal with cross wind. In fact, it was totally dangerous. We had to equipped it with and underbelly fin to regain stability on crosswind.

I see that your homebuilt cub have a larger fin, but, still, it becomes less effective when you have flaps and the nose pointing up.

Louis

 

[skywagon8a]

The test that Louis refers to is for directional stability: "Trim power off at 1.3Vs, displace the rudder to yaw the plane, release the rudder and it should return to straight with less than two oscillations. If it does not return on it's own then you will need more vertical tail area. Sometimes squared off floats such as these are more prone to to instability than are round top floats. Thus the reason that the Wiplines need the fin. I got a field approval to install a fin on a PA-18 on Wiplines. It really needed it.

 

[mvivion]

The 1 degree that MTV refers to seems unusually flat. Does MTV know what the angle is between the keel and the wing chord line on the Husky?

Not my number--from the factory-the model A-1 on EDO 2000 floats. They actually wanted to go to 0 degrees, but the FAA wasn't comfortable with that, so they started at 1 degree, and never looked back. And, that's by far the best performing Husky on floats.

MTV

 

[wheat]

When installing 2870 floats on a SuperStinson, I measured the angle of incidence between the float tops and bottom of the wing on all the planes at Kenmore Air. They ran from 0 degrees to 5 degrees. The Stinson started out at .5 degree and was slow off the water. It was changed (shortened the rear strut) to 4.5 degrees, and made a dramatic difference in off the water performance with no discernible change to cruise speed at same MP. It was interesting how much variety there was between the same type of aircraft.
I spoke with a couple of 180 pilots who had the same floats. One said that his was slow off the water and had 0 degrees of incidence and the other guy said his was "just fine" at 4 degrees. Interesting anyway.
Jim

 

[C-FIJK]

I found a set today
AUQUA 1900 FLOATS • $8,000 • FOR SALE • Aqua 1900 floats with complete PA-18 rigging. Fresh water use only. Good keels and only minor dock rash. These floats are not beautiful, but are good solid floats and a great way to get on the water this summer. Asking $8,000 or possible trade for Federal AWB wheel skis w/ Super Cub rigging. Prefer email. • Contact Chuck Geissler, Friend of Owner - located Stanton, MN USA • Telephone: 507-263-5645 • a set cheap

 

[Bill Rusk]

Per my friend and very knowledgeable float guy, Lytle, it also makes a difference where the floats sit fore/aft. This impacts where the step is relative to the CG of the aircraft. This is adjusted by the length of the diagonal tube. This is the stuff guys like JJ frey know about. He has posted here in the past. It would be nice to have him weigh in on this.

Bill

 

[Bugs66]

Regarding finlets on tail, I watched a presentation from a major float manufacturer who were getting the Super Cub certified. He said they did extensive testing with the finlets on the Super Cub and despite several iterations of different sizes and locations, they never achieved the stability they were looking for. So on a whim they tried without the finlets and low and behold it was perfect. This was Super Cub only. It could vary from different float designs but might explain why you rarely see finlets on Super Cubs.

 

[C-FIJK]

Oli when you make the rear float strut make the first set adjustable with 4-5 holes so you can try different angles and see what works best !!!!!))

 

[skywagon8a]

The shape of the floats has an effect. The round top EDO 2000s do not need an extra fin. Some of the squared tops do. It has to do with the airflow over the forward part of the float when the plane is placed in a skid. The squared sides create a side turbulence that resist the return from the skid. Oli's new floats may need the fin. See post #71.

 

[Olibuilt]

Fabricating the rigging is not easy for a beginner.... Been practicing on a bare SuperCub fuselage.

Tried to follow the plan posted earlier. But I'm having some difference with a SuperCub on Wipline amphib I've been mesuring: About the same mesure from the front bottom of the wing to the top of the float, but 4'' more from the rear bottom of the wing to the float.... The steps are both located in the middle of the chord (plane level).

??Is a Wipline 2100 amphib top of the float parallel to the keel??

With the airplane level, I placed the floats 3 degrees down (like in the plan shown earlier) and the step in the middle of the chord of the wing. Prop clearence is about 3 more than the amphib cub but less than suggest in the drawing (mine has the thrustline mod).

Still trying to figure out the ''good'' height of the plane....


The other thing that concerns me is the rear ''ajusting'' leg for testing. With the rigging at 45 degrees, won't it be too much stress on the front attachment block while raising or lowering the rear leg??


Some pics:

 

[aktango58]

Just remember: every Super Cub frame is identical to the next one, and all parts just 'bolt right up'.....


RRRRIIIIIIGGGGGGGHHHHHHTTTTTTT!

 

[Olibuilt]

Thanks for the advice. It's why I practice with cartbord and a bent fuselage in the garage rather than rigging material and my crooked experimental cub hanging by a cloud outside in the windy field. I hope to have learn a lot when I'll be rigging mine.http://www.google.ca/url?sa=t&sourc...dzaNjH1rg&sig2=L6G7wX1ej0xCA9GmiWxzxg&cad=rja

http://www.google.ca/url?sa=t&sourc...dzaNjH1rg&sig2=L6G7wX1ej0xCA9GmiWxzxg&cad=rja

 

[irishfield]

1 x 3 strapping is the perfect item for making the "redneck" float plane. Makes for good patterns to measure twice and cut once on aluminum!

Here's the first Murphy Elite onto Clamar 2200's in the world ! Yes. my work.. my hangar.

 

[Olibuilt]

The plane is now on floats. Everything seems to be ok after the hard work. The ''practice'' rigging on the bent fuselage is fitting perfectly on my basement built cub.

The predicted floating line was right on, just lucky.....

The floats seems to be well adapted for the plane. Takeoff with 2 guys on board with around 200 pound of gas is at around 40 mph for now. The floats are rapid to jump on the step and don't seem to stick on the water. I'm really satisfied of the 20 takeoff-landing I did. Time will tell if they are good for my plane in the long run.



http://youtu.be/Gcwb0m9wyhA

Thanks to everybody that help me.

 

[skywagon8a]

Congratulations Olibuilt, It looks great. You have an enjoyable summer ahead of you.

I had trouble getting the video to run a second time. It appears that if you were to use more flaps on take off, you would get a smoother lift off at a lower speed. What flap settings do you have available? You could use as much as 20 degrees without them causing excessive drag while providing good low speed lift. This will move the center of lift aft reducing the tendency of the tails of the floats to touch the water.

 

[Olibuilt]

About 20 degrees of flaps was used in the first takeoff. Did not even notice the tail of the floats dragging the water. Lack of experience and probably a little stress..... After more testing, about 35 degress seems to have the best result. Flaps settingsare bettween 0 and 65 degrees.

 

[wheat]

An old rule of thumb is to roll your aileron over and match the flap to that deflection. Seems to work perfect most times.
Jim

 

[Olibuilt]

Done a little practice. About 30' of flaps with almost full ailerons to lift one float seems to work best. Been practicing on a medium size lake to scale down my landing spots. Beiing a low time pilot, I had only landed on big lakes and big rivers.

Video with the GoPro strapped on my head:
[video]http://www.aeronefmontreal.com/index.php?option=com_content&view=article&id=57&Itemid=62〈=en[/video]

 

[beaver18]

olibuilt it seem to me that you dont have enough opening angle on your instalation if you have to use a lots of aileron for take off and lots of flaps you need more angle of attack on the aircraft, normaly a cub will only need a little flaps for a good take off.

 

[Olibuilt]

Getting ready to put the floats on again. I want to increase the angle to see if the plane takeoff better.

Was thinking making new rear legs about a inch shorter. Do you think it will be enough??




Last year video:

At 25 seconde of the video:

 

[Olibuilt]

At 55 secondes in this one:

Thanks!