Float Plane reinforcements for 4pl

[Robert440]

Working today on the ever frustrating material lists and I'm trying to figure out which parts need to be changed out in order to prepare for possible floats. So far I've picked up on the two diagonals from station PB to ND and the port diagonal and vertical of station ME. I also figure I'll need to mount some tabs for a ventral fin and rear mounts for the floats. I'm I missing anything else as far as the fuselage goes? Thanks

[alaskabearhawk]

Certified aircraft that have never been on floats routinely have to have a “float kit” installed, strengthening the points of the fuselage where the aft fittings go and sometimes at the gearbox. When you think about it, floats are completely unforgiving and there is no suspension. The airframe takes a real beating…just like a boat. If you have ever been in an aluminum boat going 40+mph on water, even the slightest chop gets your attention. In an airplane, all that force gets transmitted directly to the airframe via the attach points. There are a number of factors that need to be addressed in addition to the attach points. If a ventral fin is required, the attach point specified in the plans is one station too far forward to be effective if you were to install one similar to a Maule or Husky. Attach points need to be added for cable pulleys, water rudder retract cables, etc, etc Here is the youtube link for Rob’s BH float install: http://www.youtube.com/watch?v=On1FWllDybs

The pictures include some ideas I got from Dallas Shell and Dan R. After a conversation with Bob about the float install back in '08, I changed the tube at the bottom of the cargo door from a T10 to a T11. All those mods have been approved by Bob. The last addition that I MAY do is add a short piece of T10 to help transmit some load from the aft right attach point to the lower longeron. I will do this only after getting approval from Bob. See the attached pics. Attached is a capture of the Maule ventral fin detail pdf. I can't get the stupid file to upload on this forum.

I hope this answers any questions. Flying on floats is a blast, but it does beat the crap out of the airplane.

[Robert440]

Thanks for the info. I saw that the VR3 tubing guy specifies thicker tubes in a couple of different areas but didn't add any additional bracing as you guys did. I would think that your additional bracing would be a big help especially at the rear attach points. I've been following along with your videos and I'm picking up some good info. I used your tip about using the art portfolio for holding plans and it's been working out great!
Thanks,
Robert