seaplane floats question

[eatthis]

can you have outrigger floats that are full of fuel or not?

[The Rat]

I doubt that you could have them full of fuel, although some portion may be okay. Fuel is lighter than water, but filling a float would affect the bouyancy to such a degree that they would no longer work effectively. The math shouldn't be too difficult to work out. Take the displacement necessary for floats to support the aircraft in question, then calculate how much weight of anything you could put into the floats before it would no longer have enough bouyancy. I could see it being easier if you are talking about the wing floats on a flying boat, the hull supports all of the aircraft's weight, with the wing floats really only there to keep the wingtips out of the water.

[PR19_Kit]

AFAIK at least one of the 8 or 9 Late 631 monster French 'boats had fuel in its outrigger floats.

Every one of them was different, thus the bit about '...at least one....'. These floats were huge, as the aircraft itself was the largest in the world at the time it was built and the outriggers were about the size of a whole Grumman Goose, so there was plenty of room to play with. Sadly none of the 631s still exist but Contrail did a MONSTER vacform some years ago. My club's secrtary, Hilton Jones, build one some years back and it's one great looking aircraft.



From Jacques Perret's site at http://jacquesperret.zumablog.com/index.php

[pyro-manic]

IIRC the Supermarine "S" racers had their fuel tanks in the floats, in fact more on one side than the other to offset the torque from the monster "R" engines. But they weren't anything like full of fuel.

[eatthis]

pretty much what i thought cheers

[kitnut617]

The idea behind this was that it would have fuel tanks stored in the floats, in this case three 300 Gal. ones in each. Mind you these tanks would only occupy a small portion of the float.  The idea was this is an RCAF Pacific arena bomber originally which then got used for Long Range Patrol and Rescue.  When I worked out how big my floats should be I only calculated for about 2/3rd's of the floats supporting the 'All-Up' weight of the aircraft.