Float design for performance - some concepts and experiences

[kg]

I have what looks like a plug or cap on the outside of the spreader bars. I looked at another set of 2960s and they don't have these. They just have the open end of the spreader bar exposed.

Reference post #48 above, perhaps it would be beneficial for me to find and install these additional fairings. I don't care about a knot or two of cruise speed but if they help getting off the water ........

My plane is coming off floats today. I'll try to get some pictures of the bottom of the floats for comparison to the others.

 

[BC12D-4-85]

There's a few EDO's in Fairbanks that still have some of the original fairings. Most get lost or discarded especially if float gear changes are an bi-annual event.

Actually this summer has been a slow one for float flying. First a month or more of poor vis due to forest fire smoke, then the rising cost of 100LL now near $8/gal. That and pilots aging out or losing interest has reduced the floatplane traffic, and conventional gear too for that matter.

Gary

 

[skywagon8a]

View attachment 62456

I have what looks like a plug or cap on the outside of the spreader bars. I looked at another set of 2960s and they don't have these. They just have the open end of the spreader bar exposed.

Reference post #48 above, perhaps it would be beneficial for me to find and install these additional fairings. I don't care about a knot or two of cruise speed but if they help getting off the water ........

The plug is expansion foam to keep stuff out of the hollow spreaders. The fairings you are missing will only effect speed. They will do nothing for the takeoff run. Post #48 is addressing the 2000 floats which have a triangular flat plate holding the spreader to the outside of the float, unlike yours which passes through the float. If you don't care about ant potential drag reduction..... forget about them.

 

[BC12D-4-85]

Pete,
Do you know or have you heard of the speed increase available via typical float fairings? Just a rough guess would suffice. I can see some getting on step if the rear spreader submerges (like it can do) and the spreader attachments brackets have a flat face into water flow (like the 2K's mentioned above). But in the scheme of things all those rudder control wires, flying X wires, struts, boarding steps, fuselage and float fittings, cross-float wire, exposed hatch covers, and so on create drag. It's amazing the ship still can fly.

Gary

 

[skywagon8a]

I've never heard any specific numbers mentioned other than the Comanche had a considerable increase in speed with the fairings. I've also never made any attempt myself in researching any differences. EDO did make a version of the 2870 with enclosed water rudder controls in a cleanup effort. I've forgotten why they dropped the idea.

I do know the spray plates on the bows of the 3500s reduce directional stability enough so that I left them off all the installations I did after the prototype.

 

[RaisedByWolves]

Here’s the only pic I have of the 2000 fairings. The new ones came as one piece, the old ones were split, so I did the same to the new ones. The cub was faster on floats than wheels

 

[kg]

I know this is primarily about Cub size floats but for reference these are the bottoms of Edo 2960s.





Aft of the step:

 

[StalledOut]

Pete,
Do you know or have you heard of the speed increase available via typical float fairings? Just a rough guess would suffice. I can see some getting on step if the rear spreader submerges (like it can do) and the spreader attachments brackets have a flat face into water flow (like the 2K's mentioned above). But in the scheme of things all those rudder control wires, flying X wires, struts, boarding steps, fuselage and float fittings, cross-float wire, exposed hatch covers, and so on create drag. It's amazing the ship still can fly.

Gary

I had the Edo 2000's re-lacquered a couple of years ago. A guy in Wasilla did that work. He destroyed the fairings when he took them off. I got them back in a box but all torn up. I ordered some from a outfit in Canada. Used the old ones for a pattern, but when he did the floats he filled the holes with rivets so it took a little effort to get everything back together. Most people say you don't need 'em. My cruise on a calm morning was right around 100 IAS.

Now I am back up to the 106/107 range and it's quieter.

We had a twin comanche for a while in the family and there were Lou Presti speed mods put on that made a difference. Cleaning up small things can net surprising results.

 

[BC12D-4-85]

This is where we get to the term - equivalent flat plate area. That's words for adding a flat plate facing the aircraft in flight equal to the surface area and resulting drag of...in this case....those unfairinged (not a word) float to strut fittings for spreader bars into floats. So yea they are probably drag inducing things as they're flat into the wind and water. Alternatively, I suppose anything resembling a golf ball will pass air relatively unhindered. Wind tunnels are made for this stuff to test the options for reduction of drag.

Gary

 

[skywagon8a]

I know this is primarily about Cub size floats but for reference these are the bottoms of Edo 2960s.

This thread is about all sized and shaped floats. An expansion of the overall knowledge base is always productive. If some little tidbit is presented here which makes one more aware and can help to make an improvement in the floats, their installation, safety or anything else, is all welcome. As time marches on much personally acquired knowledge becomes just hearsay. This is just one attempt to "make a hard copy" of that knowledge.

 

[RaisedByWolves]

Edo 339-JHS/ 2250 anfibs.

 

[RaisedByWolves]

http://www.aerofairings.ca/parts.htm


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[RaisedByWolves]

this is what I ended up with on the 2000’s. Spilt them in half
The original ones were screws and nuts holding the fairing on.

 

[skywagon8a]

The original ones were screws and nuts holding the fairing on.

Should have been tinnerman nuts.

 

[mvivion]

Edo 339-JHS/ 2250 anfibs.
View attachment 62671
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Great floats! Unfortunately, EDO didn’t build many sets.

MTV

 

[RaisedByWolves]

Should have been tinnerman nuts.

That would have made my life easier. These were mid 90’s floats built by lake in Sanford Maine. I’m assuming they were original. They also had stripcaulk around all the screws. Aerofairing also has the lake heater delete fairing, and a bunch of cub parts. The quality was really good.


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[RaisedByWolves]

Great floats! Unfortunately, EDO didn’t build many sets.

MTV

I’m happy with them. Electric pump would be nice, but I can’t complain with the price.


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[skywagon8a]

Great floats! Unfortunately, EDO didn’t build many sets.

MTV

!0 sets. There was rumor of 100 sets being built for the Army for use on L-19s but no documentation of this could be found. So 10 sets total and Tom's is #10.

 

[RaisedByWolves]

I talked to J J when I got them he said they were identical to 2250 for the bird dog, except the internal valving in the shock struts were different for the higher weight. He said they didn’t work too well on the bird dog, and didn’t know how many sets were made for the military


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[mvivion]

A friend had a set on a 172 with 180 hp. Worked good on that.

MTV

 

[Douten]

Damn Tom those look fast, Something has happened to my 11 I've lost 10 mph or more since we flew at Jims ;-).

 

[RaisedByWolves]

Damn Tom those look fast, Something has happened to my 11 I've lost 10 mph or more since we flew at Jims ;-).

Oh dang. That’s too bad. I feel for you.


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[cubdriver2]

Glenn

 

[cubdriver2]

View attachment 62724

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Glenn

 

[Farmboy]

Jeez Tom, this photo makes it look like your floats are on skis…. Hmmmm…..


Transmitted from my FlightPhone on fingers… [emoji849]

 

[Farmboy]

I have zero float experience but I find it so very very similar to the hill designs of ski boats (which I am familiar with).

Lifting strakes and running pads, spray chines and deep entry keels, smoothing out to a planning surface…. All for a little bit more performance.


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