Grumman Albatross (oz10770)

About this Plan

Grumman Albatross. Radio control scale twin-engined flying boat model, for electric power. Uses 'block' blue foam construction method.

This plan is a free download available from the Model Aviation site at https://www.modelaviation.com/grumman-albatross where it appears along with the full build text and some great build pics.

Quote: "Anyone who has attended a float-fly would agree that splash-and-gos might be the main reason to take our equipment to the lake. Flying boats are right at home and forgiving in this flight mode, and that is why they are my first choice for a floatplane.

Many modelers are opposed to Styrofoam construction, but the material is inexpensive, easy to work with, and floats as well as it flies. This design takes advantage of all of these things in a scale package: the Grumman Albatross.

Construction starts with the fuselage, where sectional construction is employed. The fuselage section patterns are bonded to card stock then folded and cut to make a complete pattern. The patterns are used to mark 1-1/2 inch thick Styrofoam that is available from home improvement stores. Be sure to mark each segment with the centerline, waterline, part number, and the middle portion that will later be removed.

A temporary bond holds the sections together for shaping. One drop of epoxy will make a bond the size of a dime, so four to six drops per section are all that is needed. I used weights to apply clamp pressure while I aligned the centerlines and waterlines, and then let the tack bonds set up. On the bonds that cannot be clamped with weights, masking tape is used, under tension, to hold the sections together.

Now that the sections are together, the sanding starts. I used 90-grit sandpaper to remove the corners. Use a petting motion and sand in one direction. Use light pressure and allow the sandpaper to do the work. Clearing the debris often helps the sandpaper remove material. When the fuselage shape is getting close, switch to 120-grit sandpaper then finish with 180-grit sandpaper.

Before the fuselage is taken apart for hollowing out, the centerlines and waterlines should be redrawn to ease reassembly. To disassemble the fuselage, push a fine string in between the sections like dental floss, bring the ends together, and pull in opposite directions to upset the bond. Don’t try to pull the sections apart by hand because your grip points will dent the foam.

To hollow the fuselage, remove the foam from the center of the segments. A scroll saw is the best tool to use for the job because you can drill holes in the center of the segments and cut the material free without compromising the outer skin. However, cutting several sections at the same time with a hot wire saves time and makes a smoother interior.

To assemble the sections, simply stack them with weight applied while the epoxy sets up. There are a few tricks though. Apply only enough epoxy to make the bond surface glossy. This will reduce squeezing epoxy out between the sections. Do not apply epoxy to the outer edge of the sections; epoxy near the surface will complicate future sanding..."

As seen in the August 2017 issue of Model Aviation.

Note the plan here has been split down the middle into 2 sheets, just to make it more usable. For a single-sheet plan, see the original plan download on the Model Aviation site (although it is a hefty 13.5MB filesize).

A short kit, and ABS moulded engine cowls are available from https://parkflyerplastics.com/

See the prototype build log on RCGroups at https://www.rcgroups.com/forums/showthread.php?2862722-Grumman-Albatross for much more detail and many excellent photos showing this contruction technique.

Also for more information on these construction methods, see the book 'Building with Foam' by Keith Sparks, available from http://parkflyerplastics.com/cart/index.php?main_page=product_info&cPath=29&products_id=644

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