> 2b) To start using controls, first set the cutoff switch to true, then > starter > switch to true. When N1 is above 15% set cutoff switch to false. > > > Does your model worry about things like APUs, fuel selectors, ignition > switches, etc in the start sequence? Or is this more of an accomodation to > fit into the FG data structures. If one wanted to accurately model engine > starts (aero and thermo aside) what would be the procedure as per the > dash-one.
The model assumes the starter has whatever power source it needs to turn. The model ignores the ignition control, so you can assume ignition is always available. Starting and stopping is done with the cutoff control, and it's assumed that this one control takes care of whatever fuel valves and ignition is needed for starting and running. The requirement for 15% N2 is hard-coded, one size fits all. The 15% N2 requirement also applies for airstarts. There is no penalty (ie. hot start) for trying to set the cutoff switch to false before 15% N2. The starter switch automatically sets itself to off when the engine reaches idle. For the 737, you need pneumatic pressure (30 psi minimum) from either the APU or from an external huffer or bottle. You need a battery or external electrical power for the switches, valves and ignitors (each engine has two ignitors; each "right" ignitor is powered by the standby buses, so it's available with battery power only). To start, once you have minimum pneumatic pressure you move the start switch to GND, and the switch is held there by a solenoid. The engine will spin up, usually maxing out at about 25% N2 (about 5% N1). At any N2 above 20% you can move the start lever from CUTOFF to START, which opens the neccessary fuel valves and starts ignition (which ignitors are used is determined by the IGNITION switch, which can be in LEFT, BOTH, or RIGHT. Any position will work if all the AC busses are powered) At about 47% N2 the start switch solenoid releases, and the switch snaps to off. The engine will overshoot idle briefly then settle back to about 60% N2 (N1 about 23%). Dave -- **************************** David Culp davidculp2[at]comcast.net **************************** _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
