DC-3 Development Update 8: Fuel System

[ilias.tselios]

A disclaimer before dive into the fuel system. There are a ton of different fuel system configurations on DC3s/C47s. Some have 3 tanks, some 4, others can take extra fuselage tanks, others have crossfeed valves, others don't. Here we are simulating one specific configuration, of a specific DC3 aircraft, as described below. Also, here, will not cover the parts related to the engine operation, like priming, mixture etc.

1. Description

DC3's fuel system is not a complicated one, but because of the lack of automation, the pilot should always be aware of the fuel situation, like fuel remaining per tank, tank imbalances, etc. There is no crossfeed valves or transfer valves.

The fuel system consists of 4 fuel tanks, 2 main with capacity about 212 US GALS, and 2 auxiliary with capacity about 204 US GAL. The auxiliary name here is a bit misleading, since they are not connected to the main tanks, and are separate. Better think of them as 4 tanks.

There are 2 fuel selectors on the pedestal, 1 for each engine. The have 5 positions, 1 for each tank, and 1 OFF. You can select to feed each engine from any tank, even both from the same one!

Next in line are the firewall valves. Controlled by 2 levers on the left side of the pedestal, restrict fuel for reaching the engines.

The fuel booster pumps (1 per engine) are next, controlled by respective switch on the right overhead panel. Also there are 2 amber lights that indicate when a pump is in operation. These pump feed fuel the engines when they are not running, and used for backup during take offs and landings, in case of an engine fuel pump failure.

The engine fuel pumps, feed with fuel the engines after start up to shut down. There are no controls for those pumps.

Finally the fuel reaches the carburetors. Their operation will be described in a separate post.

 

2. Fuel Loading

Using the LES GUI, you will be able to load the aircraft with fuel, as you want. The loading is done in US GALS, which is volume, so the weight of the fuel is calculated using the fuel's density, which is depended on the fuel temperature. The weight of the fuel is displayed of the right side below the graph in kilos and pounds.

 

We have made the DC3 FSEconomy compatible, so when you start the flight in FSE, the fuel loading is disabled.

 

To wrap it up, there is a fuel indicator where you can check the fuel in each tank with the selector. In true "Douglas" fashion, the indication is not in US GALS but in LITERS!