Martin P5M-2 (oz16859)

About this Plan

Martin P5M-2 Marlin. Free flight scale model twin seaplane, for rubber power. Wingspan 36 in.

Quote: "MARTIN P5M2 MARLIN
36” SPAN TWIN RUBBER POWER FLYING BOAT

The Martin P5M Marlin (P-5 Marlin after 1962), built by the Glenn L. Martin Company of Middle River, Maryland, is a twin piston-engined flying boat that entered service in 1951, and served into the late 1960s with the United States Navy performing naval patrols. It also served with the United States Coast Guard and the French Navy, with 285 being produced.

Development: Built as a successor to the PBM Mariner, it had better engines, an improved hull, and a single vertical fin tail. The XP5M Marlin prototypes were based on the last PBM-5 Mariners, the company designation being Model 237. The type was heavily improved, again leading to the P5M-2 (Model 237B), which was redesignated SP-5B. A number of P5M-1 models were also used for training, designated TP-5A (after 1962).—Wikipedia

CONSTRUCTION:

Be sure to cover the plan with plastic kitchen wrap to keep the balsa from sticking to the plan.

WING: The wing is constructed using the cracked rib method. There’s a tutorial on Outerzone here: Cracked Rib Wing Construction (oz16738)

To round out the leading edge of the airfoil I suggest adding a couple tabulator spar of 1/16”x1/8” and another one of 1/16”x1/4” on the 1/16” edge. This will add strength and also make the airfoil more pleasing and aerodynamic in flying. Use wood dimensions noted on the plans for the wing construction.

Wing jigs made of foam board (I usually get mine from the Dollar Store) it’s approximately 1/8” thick. Make three as shown on the plans with interlocking feet. This will aid in the construction of the wing. I suggest using triangles or squares etc. to keep the spar vertical on the jig. Shim as necessary. Next join the leading edge (L.E.) together to follow the jig layout. Remember to do this with the L.E. on it’s edge so the bottom of the rib can join with a slight taper in the leading edge of the rib. Once all the bottom of the ribs have joined the L.E. and T..E. Add the main spar in place over the bottom of the ribs. In laying down the bottom of the ribs remember to add 1/16”x1/8” ribs in the float and nacelle locations for adding them later to the completed wing. Once the spars are in place add the upper cracked 1/16” SQ ribs over the spar and glued to the L.E. and T.E.

FUSELAGE: The fuselage is built using the box method where the first side is built over the plan using 3/32”SQ longerons, uprights, diagonals and cross-members. When the first side is dry, using plastic wrap over the first side, build the second side over the first to have two identical sides. While waiting for the second side to dry, use this time to make the templates as shown on the plan for joining the sides together. Leave a 3/32” gap at the top and bottom of the templates so you can add the cross-members over the templates. The sides have a narrowing at the top for the formers to be add to. Note when adding the top and bottom formers (1/16” sheet) they don’t always align with the cross-members. This has to do with fuselage shape and bottom hull step etc. Add the stringers size of your preference and whether you’ll cut notches into the formers. I like to hold them over the formers in place and with a sharp pencil mark the location of the notch. Take time to align them carefully.

EMPENNAGE:
HORIZONTAL STAB: The horizontal stab is built in two panels using 1/8”sq balsa. Once dry the panels need to be sanded to an airfoil shape and on the root edge to give 1.25” dihedral.

VERTICAL STAB: As is my usual choice, I like a fuller airfoil shaped vertical stab. To achieve this I like to build the outline flat on the building board and when dry then lift off the board and add the vertical 1/16” sheet spar using super glue to attach to the top of the vertical outline. Once dry begin adding the 1/32”x1/8” strip ribs, gluing over the spar and to the L.E. and T.E. Be sure to alternate from side to side to keep the tension even on each side. Start at the top and work down to the base of the stab. Once all glued up sand smooth and finish for adding tissue.

I hope you find this guide helpful but I realize all of us modelers have our own favorite way of putting models together. Let me know if there is major flaws that I need to address.

Well here’s another flying boat and you’ve just have to love those gull wings. Enjoy and let us know how your model goes.
Regards,
Tom Akery/Sky9pilot

Thanks again to Steve and Mary for this great site!!!"

Direct submission to Outerzone.

Quote: "Steve and Mary, I've finished a couple more plans... Dave in the posting of the Boeing XPBB-1 Sea Ranger (oz16831) asked for a plan for the Martin P5M and asked for both versions option. I favored the "T" tail of the P5M2 Marlin and included the empennage of the P5M1a with standard tail setup. It should be easy to build either version from this plan. But this plan is not for a beginner! The gull wing is a challenge in itself.

Thanks again for you great site! Still exploring all various pages!!
Regards,
Tom Akery/Sky9pilot

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