Old Timer and float planes

[Gregor77]

This is more directed to Piker...

I have a heavy 3 channel oldtimer with the classic wings 80".  I was sketching different things to do this this plane.  I love doing the float fly and with the wings being easy to take off, it would be great.   I am wondering what is the best way to bolt the floats on and how big should they be?  I know it wil be hard to determine based on images.

My concern is 4 channel better for something this size rather than put it on water?

Also anyone know what this model is called?

[Gregor77]

I am planning on pulling the covering off and doing it antique solartex.

[piker]

I think this would make a great float plane (would you expect me to say any different?).  The light wing loading will make it a nice, gentle float plane ideally suited to fairly calm winds.  Mainly because the high wing with lots of dihedral will make the plane more susceptible to being tipped over by a cross wind while on the water.  But the sight of seeing the plane take-off effortlessly, gracefully cruise overhead, then lightly touch down on the calm water will be worth it.

Three channels is fine.  My first float plane was a three channel plane.  No problem.

The standard practice for choosing the float length is to measure the fuselage from prop back plate to rudder post and multiply by 80% (., then choose (or build) a set of floats as close to that as possible.  Another option for that type of plane is what's called "Antique" or "Old Timer" style floats (see picture below).  They're teardrop shaped (usually) with the TE of the float acting as a step, and the tail of the plane sitting on it's own little float.  These are the type I'm considering for the SE5a. 

The "size" of the floats (the width and depth) will depend on the weight of the plane.  The general rule of thumb is to have each float alone able to support the weight of the plane when sitting in the water.  The second float then creates a 2x buoyancy scenario for stability and sufficient area above the waterline.  Buoyancy can be guesstimated or calculated, or determined by experimentation to find the amount of water in weight displaced by the float.  Here's a simple way to determine the buoyancy of a float (or anything for that matter).  Get a pail or something similar that the entire float can fit inside.  Put that pail on a tray to capture over flowing water.  fill the pail to the very top with water (just about to overflow...doesnt' even have to be level).  Submerge the float entirely into the water and allow the water to overflow.  Collect the water and weigh it (tare out the container it's in).  The weight of the water will equal the weight of the object to be kept afloat (including the weight of the float).  But that would provide neutral buoyancy, hence the general rule for doubling the buoyancy.  Another way is to determine an approximate volume of the float and multiply it by the weight of water.  Or, just go with the "looks about right" approach, which is what I do 

As for bolting the floats on.  Usual style floats will need a hard point glued into the fuselage roughly below the TE of the wing for the rear strut mount to be fastened to.  The Old Timer Stle floats can mount in the same way as the wheels.  You MAY even get away with using the same struts as the wheels, except they may be too narrow.  Standard floats mount with the tops at a slight negative angle to the chamber line of the wing (the incident line) with the step below the CG point.

Robert

[williame3590]

Looks like a Buzzard Bombshell Greg, 1940. If I seen a photo with the wing on it would be easier.

Bill

[williame3590]

Here is a couple of photos

Bill

[Gregor77]

Nope.  Wings are a bit flatter and pointed. The window looks different too.  I will take some tonight.