Please check my set up with a E-Flight J-3 with floats.

[Gregor77]

Hey guys, I was putting together an E-flite J-3 and I finally got the power system installed.  I was using an HK 40A esc with new SBEC.    A G25 870 kv with a 10X6E prop. (E-fl recommends the 11X7E)  4S, 2200, She pulled 500 watts at max 100% throttle and about 180-200 at half.  It draws 31.2 amps full and 6.7 at 1/2 throttle.   The specs on the plane show that it is with NICD's roughly 4 lbs.  This might be over kill, but I was planning to use the E-flight floats.  I assumed more power is better.  The C/G seems right with a small pack (assuming the HK motor is a bit heavier than the E-flight).  Ben, what battery where you running?

Hope everyones projects are moving along with no issues.

[piker]

Hey Greg,

I recalled seeing this thread but hadn't provided my "input" yet, so here it is!

First:  Seaplane = Awesome!

Second:  The power to weight ratio of approx. 125 w/lb is way more than enough.  Even if the floats put the weight over 6lbs you'll be fine, provided the wing loading is kept reasonable.

BTW, does everyone know how to determine, and what is generally accepted as reasonable wing loading?

Wing loading is the flying weight of the plane (in oz.) devided by the wing area in square feet).  For example.  Say Greg's plane comes out to 5 lbs with the floats.  That's 5 x 16 = 80oz. flying weight.  Say the wing area is 700 sq.in.  Take that 700 / 144 (number of inches in a square foot) = 4.86 sq.ft.  To get wing loading ... 80 / 4.86 = 16.46 oz./sq.ft.

"Appropriate" wing loading, of this type, varies with size of model, and there is a fairly large range of what will work.  I would consider a wing loading of below 20oz./sq.ft for a plane of this size and style (a slow flying, lightly loaded Cub) to be ideal.  16 would be even better and would just make the plane fly better (slower and more scale like but would get tossed around by gusts a bit more) and up to as much as 25 would be O.K., but at 25, the plane would fly faster, require more power to take-off and fly level, and would land faster.

Faster, more heavily loaded type planes (WWII fighters etc.) would be better suited to higher wing loadings to allow them to "groove" better, but generally, lighter is better.

Other opinions guys?