CAPTAIN SIM
LOCKHEED L1011
DIRECT LIFT CONTROL
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Contents
Getting Started
Direct Lift Control – The basics
Direct Lift Control – Conditions
Direct Lift Control – Notes
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4
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Copyrights and usage
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Getting Started
Welcome to the first in a series of documents explaining the systems of one of
the most advanced airliners of the 1970s – the Lockheed L1011!
The L1011 manual series will be composed of information documents on aircraft
systems and tutorial flights.
It is recommended that the documentation supplied with the Captain Sim
Lockheed L1011 is read prior to reading this information document and that one
has a basic knowledge of the L1011 and its cockpit.
The Lockheed L1011-1 first flew in November 1970 and entered commercial
service with Eastern Airlines in 1972. The L1011 was in direct competition with
the Douglas DC-10, another trijet from the era. Unfortunately only 250 L1011s
were ever built, however the advanced and sophisticated technology that
featured in the L1011 lived on and the pioneering automation of the L1011 lives
on today in all modern airliners.
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Direct Lift Control – The basics
Direct Lift Control (DLC) was one of the pioneering technological systems which
featured in the L1011. It was a relatively simple system and only had a few
conditions. It was designed to enhance passenger comfort during the approach
phase of flight. The DLC system also improved fuel efficiency during approach.
Direct Lift Control is automatically used during the approach phase of flight to
control the vertical speed of the aircraft while maintaining a constant pitch.
When on an ILS approach, if the pilot or autopilot demands a greater rate of
descent, pushing forward on the yoke will raise the spoilers. The raising of
spoilers decreases the amount of air flowing over the wing, therefore reducing
lift.
By allowing control vertical speed using spoilers, the aircraft did not have to
make as many pitch adjustments. This reduced amount pitch movement
resulted in a more comfortable flight for passengers.
Greater fuel efficiency was also a result of Direct Lift Control. By using spoilers
to control the descent rate, it meant the engines could maintain a constant
power. There was no need to increase engine power to decrease vertical
descent and the engines did not have to come back to idle to increase the rate
of vertical descent. Therefore because the engines did not have to spool up so
much the aircraft was much more fuel efficient during approach compared to
other aircraft from the same era.
Direct Lift Control used spoilers 1-4. Depending on the aircraft condition, the
spoilers on the L1011-1 can deploy by up to 14o to increase the rate of vertical
descent. When flaps are deployed, the spoilers have a null zone of 7o on the
L1011-1.
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Direct Lift Control – Conditions
Several conditions must be met before Direct Lift Control will automatically will
function. These are:
Flaps must be in the landing zone (28o or more)
At least 2 engines are below maximum climb thrust (MCT)
No stall warning
Aircraft must not be in a go-around mode
Direct Lift Control system channels are powered and able to operate
normally
Failure to meet any one of these conditions will result in Direct Lift Control not
functioning. Direct Lift Control operates automatically no matter what control
state the aircraft is in (manual control or automated control).
The spoiler lever in the cockpit is linked to the Direct Lift Control system, so the
pilots in the cockpit can check how far the spoilers have extended.
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Direct Lift Control – Notes
There are certain circumstances when Direct Lift Control will not work. These
are:
All three engines are at maximum climb power or greater (MCT)
Airspeed condition is creating a stall warning/risk
Flaps are not in a landing configuration
Engines throttles in reverse
Direct Lift Control often ensured a much more pleasant approach descent
phase. Direct Lift Control is not particularly effective for at rectifying a large
amount of vertical deviation from the ILS. It is designed for making small
adjustments.
No other commercial airliner feature Direct Lift Control, however Direct Lift
Control was regarding as such a success that it was used by NASA in the Space
Shuttle!
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FOR USE IN MICROSOFT FLIGHT SIMULATOR X WITH THE CAPTAIN SIM
L1011 EXPANSION ONLY. NOT CERTIFIED FOR REAL LIFE PROCEDURES.
©Aaron Graham – 2014
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