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Old 09-03-2012, 07:59 PM   #1
Phaelen Bleux
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Default [WWII] Martin PBM Mariner

Martin PBM Mariner
Designed as a complement to the Consolidated PBY Catalina (p. WW116), the PBM entered service in late 1940 and was used as late as the mid-1960s. It featured 5 gunnery positions, underwing racks for 2 torpedoes, and could carry up to 8,000 pounds of bombs or depth charges in bays in the engine nacelles. It was used for patrols and anti-submarine warfare in both the Atlantic and Pacific theaters, and was responsible, in whole or in part, for the sinking of 10 U-boats. During WWII, the Royal Australian Air Force used 12 PBMs for transporting troops and cargo.
After WWII, the PBM was used in the Korean War for long range patrol missions. The U.S. Coast Guard used the PBM for aerial search and rescue missions until the mid-1950s; the USN retired the type in 1956. The Netherlands, Argentina and Uruguay purchased PBMs in the 1950s, and continued to use them until the early 1960s. A handful were also converted to post-war commercial passenger service, with 6 crew and 30 passengers.
A PBM was lost in a mid-air explosion in December 1945 on a SAR mission looking for Flight 19. In a Weird War II campaign, it is clear that this was an alien abduction incident.
The PBM-3 carried a crew of 7-10, depending on mission profile. With a 4,000-lb. payload, it had a historical range of 2,240 miles. It burns 85.8 gallons of aviation fuel per hour at routine usage. A full load of fuel and MG ammo costs $640. Other ordnance costs vary by mission payload.

Martin PBM-3D Mariner
Subassemblies: Heavy Bomber chassis +5; Heavy STOL Bomber wings +4; two Medium AFV wing pontoons +2, two Small TD engine pods +3. All waterproofed.
Powertrain: Two 1,417-kW aerial turbocharged HP gasoline engines with two 1,417-kW props and 2,700-gallon self-sealing fuel tank [Body].
Occ.: 9 CS Body
Cargo: 89 Body

Body: 2/3, 3/5U
Wings: 2/3
Pontoons: 1/1, 3/5U
Engine Pods: 2/3

2x Aircraft HMG/.50-cal. Brownings [Body:F] (250 rounds each).*
2x Aircraft HMG/.50-cal. Brownings [Body:B] (250 rounds each).*
2x Aircraft HMG/.50-cal. Brownings [Body:T] (250 rounds each).*
1x Aircraft HMG/.50-cal. Browning [Body:R] (250 rounds).
1x Aircraft HMG/.50-cal. Browning [Body:L] (250 rounds).
4,000 lbs. of bombs or depth charges [Engine Pods:U]
2x 569mm Torpedoes/Mark 13 [Wings:U].

Body: Medium radio transmitter and receiver, navigation instruments, backup driver, autopilot, casemate mounts for all MGs, 110-mile radar, IFF, bombsight. Engine Pods: One 4,000-lb. bomb bay each. Wings: One 2,200-lb. hardpoint each.

Size: 80'x118'x28' Payload: 12.4 tons Lwt.: 29 tons
Volume: 1840 Maint.: 17 hours Cost: $138,429

HT: 7. HPs: 550 Body, 1100 each Wing, 285 each Engine Pod, 200 each Pontoon.

aSpeed: 211 aAccel: 3 aDecel: 27 aMR: 7 aSR: 3
Stall Speed: 72 mph.
wSpeed: 22 wAccel: 3 wDecel: 5 (6.5) wMR: 0.05 wSR: 5
Flotation Rating: 39.6 tons. Draft: 2.6'.

Design Notes:
Like the PBY, every effort was made to conserve weight in the design. The turrets were subsumed as part of the chassis, and the weight, cost and HP of the chassis was reduced by 50%; final design loaded weight was decreased 5% to the historical. Although maximum payload was listed as 8,000 lbs., 4,000 lbs. was more typical, and this was used. Historical payload was within 1,475 lbs. of the design payload. Historical wing area was 1,408 sf. Performance calculations were based on historical values for wing area and loaded weight. The aircraft requires a 14 mph headwind for water-based take-offs. Design aSpeed was 214; the historical value is shown.

The PBM-1 was the initial production version, with two 1,194-kW engines and only five .50-cal Brownings (one in each position). The stabilizing floats were retractable. 21 built.
The PBM-2 was to be a strengthened version for catapult launches; 1 prototype.
The PBM-3 increase engine output to 1,270-kW each and made the stabilizing floats fixed. 32 built. The -3R was an unarmed transport version carrying 20 passengers; 18 built and 31 conversions from the -3. The -3C added a .50-cal (7 total) to the nose and dorsal turrets, and added the AN/APS-15 radar; 274 built. The -3S was a dedicated ASW variant with twin HMGs only in the nose, a payload of four 325-lb. depth charges, and 4,815 gallons of fuel for increased range; 94 built, 6 conversions.
The PBM-4 was an unbuilt proposal to feature 2,015-kW engines.
The PBM-5 featured 1,566-kW engines; 628 built. The -5E featured improved radar, the -5S was a lightened version for ASW, and the -5S2 added revised radar suites.
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Last edited by Phaelen Bleux; 09-04-2012 at 12:54 PM. Reason: changed design aSpeed/headwind
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Old 09-04-2012, 07:43 PM   #2
Join Date: May 2007
Default [WWII] Martin PBM Mariner -- problem

Apparently the Mariner was famous for spontaneous detonation of avgas fumes in its tanks.

Not sure how to model this in GURPS but after, say, early 1944 this would be well known in the USN and allied air forces using the Mariner.
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Old 09-05-2012, 07:40 PM   #3
Phaelen Bleux
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Default Re: [WWII] Martin PBM Mariner

Well, the HT is pretty low, so lowering it more would be a little harsh. You could also negate the bonus for Self-Sealing Fuel Tanks. And any vehicle operation Critical Failures could be ruled as catastrophic.

Random combustion checks would be a little hard on the PCs, though!
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Old 11-30-2013, 06:17 PM   #4
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Default Re: [WWII] Martin PBM Mariner

My father flew a PBY in SAR in the south pacific.

A clock running two hours slow has the correct time zero times a day.
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airplane, mvds, usa, wwii

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