Important controls / keys
- Rudder (Aileron input is transferred to the rudder for convenience.) At low speed the rudder is automatically augmented by a tail mounted side thruster controlled by the flight control system.
Engines and thrust vectoring
The Zeppelin NT has a non-standard set of engine controls. The engines' throttles are controlled by govenors - the throttle levers select the desired RPM.
- PgUp/PgDown - Increase/decrease selected engine RPM.
- M/m - Leaner/richer mixture.
- [/] - Swivel side engines up/down. 0 - 120 degrees.
- G/g - Swivel aft engine down/up. -90/0 degrees.
- N/n - Decrease/increase thrust (i.e. propeller blade angle).
Take off/Landing: max RPM, use thrust levers for control.
Cruise: thrust levers for max thust, use engine RPM select for control.
Gas and Envelope
- F/f - Open/close the gas valve.
- Q/q - Inflate/deflate fore ballonet.
- A/a - Inflate/deflate aft ballonet.
The fore and aft ballonets (air-filled bags inside the envelope) serve two purposes: (i) by inflating/deflating they maintain the pressure differential and volume of the envelope when the gas changes volume; and (ii) the trim of the airship can be changed by the relative inflation of the ballonets. While the required envelope pressure dictate the total volume of the ballonets the airship can be trimmed by having one ballonet more or less inflated than the other.
Envelop pressure management When the airship rises the gas in the envelope expands and consequently the the total volume of the ballonets has to decrease or the envelope pressure will increase. There are pressure relief valves that automatically open when the pressure in the ballonet exceeds a set limit (which is lower than that of the gas relief valve to prevent gas being valved before both ballonets are empty) but the prudent airship pilot would rather use the manual ballonet valves than rely on the relief valves.
When the airship descends the increasing ambient pressure causes the gas in the envelope to contract and to maintain the envelope pressure above the ambient pressure total volume of the ballonets has to increase. The pilot has to set the ballonet controls for inflation. If the envelope pressure drops too low an alarm will sound. Monitor the gas pressure gauge!
Pitch trim On the Zeppelin NT pitch trimming is done via the relative fore/aft ballonet inflation rather than with the elevator trim. To trim towards:
- nose heavy - set the fore ballonet valve for inflation and/or the aft for deflation.
- tail heavy - set the aft ballonet valve for inflation and/or the fore for deflation.
The Zeppelin NT has no ballast approved for inflight adjustment. Use on ground only.
- w - Show current on-ground weight. Only works when on the ground.
- W - Weigh off to 700lbs heavy by adding/removing ballast. Takes about 10 seconds and is only applicable when on the ground.
- D/d - Drop ballast in 1%/0.1% decrements.
Ground crew / Mooring mast
- Y - Release mooring mast connection or wire.
- U - Attach mooring wire. Only possible when close to a mooring mast.
- y/u - Play out/winch in mooring wire.
- Alt + click on terrain - Place the mooring mast.
Landing short of the mast and taxing up to it allows precision control. Use the rear thruster to keep the tail wheel in the air while taxing.
The mooring mast is visible over the multiplayer network.
Note: The mooring force calculations are sensitive to long frame times (i.e. very low fps). In particular this can cause instability during FlightGear startup. One workaround is to pause the simulation immediately on startup and continue when scenery objects and multiplayers have been loaded. A better option is to reduce /sim/max-simtime-per-frame to a sane number, e.g. 0.1 meaning that each frame is at most 0.1 simulated seconds (so if your fps drops below 10 the simulation will run slower than real-time). This can be done in preferences.xml by modifying the line
Cockpit and instruments
Multiplayer dual control
This aircraft equipped for dual control over the FlightGear multiplayer network.
To use this feature the pilot sets the property /sim/remote/pilot-callsign to the callsign of the prospective copilot. This property can be set in the property browser, on the command line or in fgrun. Command line example:
fgfs --aircraft=ZLT-NT --prop:/sim/remote/pilot-callsign="someone"
The copilot uses the copilot "aircraft" ZLT-NT-copilot and sets the property /sim/remote/pilot-callsign to the callsign of the pilot. Command line example:
fgfs --aircraft=ZLT-NT-copilot --prop:/sim/remote/pilot-callsign="anybody"
1. If the pilot sets /sim/remote/pilot-callsign at runtime the copilot needs to join MP after the pilot set /sim/remote/pilot-callsign or things won't work. This will be improved in a future version.
2. Using the ZLT-NT-copilot it is possible to hitch a ride with any ZLT-NT on MP. However, unless you are the pilot "approved" copilot you will only be an observer (and will not, if there is no approved copilot, receive the full aircraft state from the pilot).
- The mooring force calculations are sensitive to long frame times (i.e. very low fps), which can cause FlightGear to crash during startup or make the airship start in a bad state.
Workaround: Set /sim/max-simtime-per-frame to 0.1 seconds or less. This can be done in preferences.xml by modifying the line
- Unfortunately the pressure alarm will sound at startup since the envelope isn't initialized in a pressurized state. The ballonet inflation levers are preset to maximum inflation so the operating pressure is usually reached within 60 seconds.
- With the current FlightGear/CVS the radio displays are broken for the copilot, although the frequency settings are shared correctly.
- Obsolete copies of mp_broadcast.nas (e.g. from the WildFire or Air racing add-ons) in $FG_ROOT/Nasal or ~/.fgfs/Nasal are likely to cause problems. Currently the up to date version resides in Aircraft/Submarine_Scout/Models/mp_broadcast.nas and Aircraft/ZLT-NT/Systems/mp_broadcast.nas. Remove the others (or if replace them with the up to date version if you want to keep Air racing functional).
- Download page with other lighter-than-air aircraft for FlightGear. Requires the LTA support available in FlightGear/CVS since 2008-07-10.