2013-3 TEMAC Tickler, scratch building classes!

[Papa]

#2013-3

[JohnA]

I interested in the scratch building cleases.

John Aurich

[piker]

EXCELLENT concept, Jack.  My only regret is, I assume I don't qualify.  I'm gonna miss the party.

But you missed one very important construction step for the Norseman.... FLOAT construction   

I hope a lot of people take advantage of this great opportunity.

robert

[Wingnutz]

EXCELLENT concept, Jack.  My only regret is, I assume I don't qualify.  I'm gonna miss the party.

But you missed one very important construction step for the Norseman.... FLOAT construction   

I hope a lot of people take advantage of this great opportunity.

robert

Happily I think I do qualify and have submitted my name. If I make the list, I want to build floats. I'm using 27" foam core floats on my Apprentice with an AUW of about 3-1/2 pounds including floats. The Unionville Norseman is a lot heavier but I'd still like to go the foam core route to minimize leak problems...anybody have an idea how big a float the Norseman would need?

[Bert Dunk]

  High Jack!

I would like to sign up.

Best regards,

Bert Dunk

[Papa]

You're in Bert # 5.

Jack.

[Tom]

Hi Jack,

Sign me up too.

Regards,
Tom

[piker]

Hey Bill,

Here's most of what I typed up in response to Greg's question about floats for his old timer.  This should apply to to Norseman too, except for the "antique" style floats.  BTW, a cubic foot of water weighs 62lbs.  So for a 5 lb Norseman, you'd want roughly 140 cubic inches of area per float (say a 26" float that's 2.3"x2.3" on average).

"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). 

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 that float can keep 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 (62lbs per cubic foot).  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.  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."

BTW, Greg is right about the Unionville floats.  I built a pair years ago and although they worked well, I was a little less than impressed by them.  They are shaped weird, with a small front end, so they certainly wouldn't look right on a scale model...as I recall.