[MVDS] Stinson 108

[Phaelen Bleux]

Stinson 108 Floatplane
The Stinson 108 was a general aviation aircraft produced from 1946-1950. It featured a steel-tube framework covered by fabric. The Stinson 108-3 was the most numerous type (1,759 built), and could carry 3 passengers at 170 lbs. each and 50 lbs. of cargo. It has a crew of one (pilot). By 1949 (when Piper acquired Stinson), 5,260 planes had been constructed. The final 325 aircraft were sold off by Piper.
The 108 burns 6.2 gallons of aviation fuel per hour at routine usage. A full load of fuel costs $10. Historical range is 500 miles.

Stinson 108-3
Subassemblies: Medium Fighter chassis +3; Recon Plane wings with STOL option +2; 2 sealed Medium Weapon pontoons +1, 2 fixed skids +0.
Powertrain: 123-kW aerial HP gasoline engine with 123-kW prop and 50-gallon fuel tanks [Wings]; 4000-kW battery.
Occ.: 1 CS, 3 PS Body
Cargo: 1 Body

Armor
Body/Wings: 2/2C
Pontoons: 2/2
Skids/Wheels: 2/3

Equipment:
Body: Medium radio transmitter and receiver (10-mile), navigation instruments, autopilot.

Statistics:
Size: 25'x34'x7' Payload: 0.54 tons Lwt.: 1.20 tons
Volume: 200 Maint.: 98 hours Cost: $4,598
HT: 10. HPs: 60 Body, 35 each Wing, 19 each Pontoon (or 12 each Wheel).

As a land plane:
aSpeed: 133 aAccel: 3 aDecel: 21 aMR: 5 aSR: 2
Stall Speed: 43 mph. Take-Off Run: 207 yards. Landing Run: 97 yards.
gSpeed: 162 gAccel: 8 gDecel: 10 gMR: 0.5 gSR: 2
Ground Pressure: High. 1/6 Off-Road Speed.

As a floatplane:
aSpeed: 115 aAccel: 3 aDecel: 20 aMR: 5 aSR: 2
Stall Speed: 45 mph. Take-Off Run: 207 yards. Landing Run: 97 yards.
wSpeed: 162 wAccel: 8 wDecel: 2 (4) wMR: 0.1 wSR: 2
Flotation Rating: 4,975 lbs. Draft: 2.4'.

Design Notes:
Historical wing area was 155 sf. The design purchases 60-gallon fuel tanks; the historical volume is listed above. Chassis weight, cost and HPs were divided by 2 to reflect a civilian design and reduce design weight. The weight, cost and HPs of the pontoons were divided by four to match values I found for the real-world weight of the pontoons. Design loaded weight was increased 3% to the historical. Design aSpeed for the land plane was 128 mph. Performance calculations were based on historical values for wing area and loaded weight.
Loaded weight for the land plane was 2,400 lbs. The loaded weight for the floatplane was determined by adding pontoon weight (307 lbs.) and subtracting wheel weight (128 lbs.), resulting in a loaded weight of 2,579 lbs. as a floatplane. wSpeed was 26 mph; this requires a 1 mph wind assist for take-off. Design draft was doubled for better realism.
Flotation rating is based on the pontoons only. (The chassis does not touch the water, nor was it designed to be waterproofed, since this is a land plane conversion.) This was taken as 312.5 lbs. + 185 lbs. per VSP for sealed pontoons. Although this should give the benefit of Fine lines, Mediocre lines actually produce a better wSpeed as they allow for planing, and so were used.
Historical purchase price was $6,484. Currently, a Stinson 108 can be purchased for about $20,000. The above design price is for a floatplane; a land plane costs $450 less.

Variants:
The 108 does not have a right-side cargo door. 741 built. It has 40-gallon fuel tanks and 112-kW engine.
The 108-1 added a right-side cargo door. 1,507 built.
The 108-2 introduced the 123-kW engine, but still had 40-gallon tanks. 1,252 built.
The 108-4 was a single higher-powered prototype.
The "Flying Station Wagon" was a conversion of any of the -1, -2, and -3 models that featured a wood-paneled interior, capable of carrying 600 lbs. of passengers and baggage. The -4 was of this type as well.
The 108-5 (1975) was built by Univair. It featured a 134-kW engine. 1 built.