Boeing XPBB-1 Sea Ranger (oz16831)

About this Plan

Boeing XPBB-1 Sea Ranger. Free flight scale model seaplane for rubber power. Wingspan 36 in.

Direct submission to Outerzone.

Quote: "Steve and Mary, I really like seaplanes and float planes and came across this unique seaplane by Boeing that was very successful but just at the wrong time. So here's the XPBB-1 SeaRanger "Lone Ranger". Got the nickname from being the only XPBB-1 produced.
I really enjoy your site. Never can get enough of those great airplane plans.
Thanks again for your hard work and great site.

Here's the plan, thumbnail and construction article
Regards,
Tom Akery/Sky9pilot

BOEING PBB-1 SEA RANGER (LONE RANGER)

The Boeing XPBB-1 Sea Ranger (Boeing 344) was a prototype twin-engined flying boat patrol bomber built for the United States Navy. The order for this aircraft was canceled to free production capacity to build the Boeing B-29 and only a single prototype was completed. To achieve the desired long range, the PBB became a fairly large aircraft, with a wingspan of 139 feet 8+1/2 inches (42.59 m) and a crew of ten.  Despite its size, it was powered by just two Wright R-3350 Duplex Cyclone radial engines, driving three-bladed Curtiss Electric propellers. It was the largest twin-engined flying boat flown during World War II. For a flying boat, the PBB was aerodynamically clean, with a cantilever wing set high on the fuselage. The planing bottom had a single step, and the non-retractable outrigger floats were attached to streamlined, cantilever struts.

The prototype, designated XPBB-1, made its first flight on 9 July 1942 from Lake Washington.[1] The aircraft handled very well and was considered technically successful. However, already in 1942 the PBB program had been cancelled: The need for a long-range flying boat had been reduced by the ability of land planes such as the Consolidated PB4Y to fly long-range missions over the ocean, and construction of a small number of PBB-1s would have a negative impact on the production rate of the B-29. The Navy allowed the Army to use the Renton factory for the production of B-29 bombers, in return for the use of another factory in Kansas.

The single XPBB-1 was handed over to the US Navy, and was used in trials programs until 1947, when it was finally retired. Despite suggestions that more aircraft might be built, perhaps by another factory, it remained the single example of the type, and was accordingly nicknamed "Lone Ranger".

CONSTRUCTION
WING:
The wing is constructed using the David Rees’ Sliced rib technique. This makes a very strong but light wing. Mike Stuart has made a great tutorial of this method and here’s a link: https://www.ffscale.co.uk/rees.htm Use the noted wood sizes on the plans for the build.

FUSELAGE:
The fuselage is constructed using the box method of construction with fuselage formers on the top and bottom of the box. The box is constructed using 3/32”sq longerons, uprights, cross members and diagonals. Build one side first and then build the second side over the first so you have identical sides. The formers are made from 1/16” sheet. The formers don’t always align with the cross members of the box fuselage. The rear is a bit tricky, you’ll see a horizontal “K” former that is creased in the middle making a “V” shape for the very rear of the boat section. The fuselage is very rounded aft of the “K” former and foam block is used to shape this multi convex shaped area. The nose block is from hollowed balsa block. Note the many shapes of this block. The nose curves to a flat area with a rounded top just under the nose turret.

The turrets and cockpit are vacuum formed or plunged molded clear plastic. There are 5 turrets, nose, rear, top and two side turrets.

STABS:
Horizontal stab is constructed of 3/32”SQ and sheet balsa. Flat over the plans.

The vertical stab is made by laminating 3 strips of 1/32”x3/32” balsa around a template. Once dry remove from the template and add the outer ribs of 1/32”x1/8” strips over the two 1/16” sheet vertical spars. Start adding the ribs from the top after the spars have been attached with super glue. This is called building in the air. This gives a very nice fuller vertical stab instead of a single sheet stab or single thickness built up stab.

I hope you find this plan interesting and fun. I realize it’s not for the beginner. But will provide a model that you won’t see everyday.

Regards,
Tom Akery/Sky9pilot

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