Towing

Towing is one of the three ways that a glider can be launched, the other two being self-launch (with an onboard engine), or stating from a slope as typically practiced by hanggliders.

There are two main towing types:

• Ground-based towing, this includes
  • the widely practiced winch launch
  • auto-tow, being towed by a driving car
  • bungee launch, where the aircraft is accelerated using a flexible rope
• Aircraft-based towing, usually called aero-tow, getting towed by another, motorized aircraft

Organization

In FlightGear, towing functionality is implemented:

• in Nasal/towing/towing.nas
• in YASim's code

A few aircraft have their own system implemented. Where there is no reason for this, these should be ported to use the global functionality.

Keymap

Note  This is a proposed keymap under the effort to unify winch launch experience in FlightGear.

Premises:

• Easy to remember keys are necessary in order to allow the pilot to quickly act during the fast and during the training phase maybe hectic experience that a winch launch can be
• Key commands should be grouped into sensible "categories", by using different actions (shift, ctrl) on the same key
• I know of no aircraft that has separated cable release levers for the different hook, normally all hooks are connected to one handle.

Traditionally, w is used for winch-related activity while o and related keys are used for aerotow (as a is reserved for time speed-up/slow-down).

Proposals:

• Use ctrl-action for initialization/start
• Use upper key (⇧ Shift) to reduce speed, lower key to increase speed (only for winch launch)

Key	Action
Ctrl+w	Place winch and begin winch launch
Ctrl+o	Connect to aerotow aircraft within range (MP or AI Scenario / Robot )
w	Ask winch driver to increase winch speed
⇧ Shift+w	Ask winch driver to reduce winch speed
o	Release all cables ("yellow lever" in most glider aircraft)