Landing the Just Flight L-1011 Pro, Assistance Needed

[John W]

I recently pruchased the Just Flight L-1011 Pro for FSX Steam. On trying to fly this aircraft I have encountered a problem when flaps are extened beyond 22. Apparently this aircraft has a feature called DLC (Dynamic Lift Control) which engages when flaps are extended beyond 22.

The DLC system engages the spoilers to control descent and essentially eliminates elevator. Consequently I can get the aircraft stabilized on glidepath but have trouble landing as pulling back full on the stick barely raises the nose and the aircraft ends up flying into the runway. I have tried using elevator trim during landing but the trim seems to be reduced with DLC engaged.

DLC can be turned off and the aircraft handles normally when this is done. But it bugs me that I don't seem to be able to figure out the right combination of control to be able to land this aircraft with DLC engaged.

So, is there anyone out there who has this aircraft and has figured out how to land it with DLC engaged? Any suggestions would be greatly appreciated.

[Licopolis]

have you tried advancing throttle before touchdown?
I don't have this aircraft but I took time to read about Direct Lift Control (that's what DLC stands for re L-1011).

[John W]

Yes I have tried advancing power before touchdown, problem is the delay in advancing the throttle. There is a significant lag and then when you push it up it takes a while to come back down. But I'll give that a try again and see if I can do a quick push up and pull back.

[John W]

Well that didn't work. There is too much lag in the response of the engines and the flight controls. Gotta love this aircraft. Just Flight puts out a manual with basic instructions and no instructional videos or information on how to fly the aircraft with DLC. And you can't fly it the same way you fly a normal aircraft.

[Morag]

There's this video on youtube which shows you how to disable DLC

https://www.youtube.com/watch?v=FGHAZGDvd-8

and a few tips in the comments on how to land with it switched on.

[John W]

Thank you for the information. I have previously watched that video which is where I learned how to turn off the DLC. With the DLC on I have been trying to use trim to flare the aircraft but it is very difficult as the trim is slow and if you're not careful you over due it and the aircraft climbs. With DLC turned off the aircraft lands normally. I was hoping to get some input from people who have the Just Flight L-1011 and have figured out how to land it with DLC turned on. I can always turn if off but it just bugs me that I can't seem to figure out how to land it with it turned on. Thanks again.

[Licopolis]

Are there any clues on DLC in the manual for the addon? Somehow I feel that disabling it in the end is a thing to do in every situation. From what information exists in the Internet I cannot seem to find anything about actual landing- it's all about how good maintaining stable glide saves fuel.

[Morag]

Originally posted by John W:

Thank you for the information. I have previously watched that video which is where I learned how to turn off the DLC. With the DLC on I have been trying to use trim to flare the aircraft but it is very difficult as the trim is slow and if you're not careful you over due it and the aircraft climbs. With DLC turned off the aircraft lands normally. I was hoping to get some input from people who have the Just Flight L-1011 and have figured out how to land it with DLC turned on. I can always turn if off but it just bugs me that I can't seem to figure out how to land it with it turned on. Thanks again.

Like Licopolis I just looked this up because it was interesting. I did find a smooth landing with DLC enabled

https://www.youtube.com/watch?v=Z32tE5_rA_g

and this linked from the JF forum

The DLC is a system particular to the L-1011 which was designed to control inboard spoilers' deflection during final approach to provide vertical speed control without significant changes in pitch attitude. In the case of the L-1011-500, when flaps are more than 30º, the 4 inner spoilers will come up to a new neutral position of 9º. If you are above your glide path, then the spoilers will vary from 9º to 20º, in order to kill lift. If you are below your glide path they will vary between 9º and stowed position. The DLC results in a smooth and constant pitch attitude approach and works automatically both in manual or autopilot operation. For those who have flown gliders, this concept is similar to the principle of using spoilers in the final approach, controlling the rate of descent without changing the glider's speed.

http://www.tristar500.net/features.htm

[John W]

The aircraft does fly approaches well on autopilot and I have been able to do landings like the one in the video above by disengaging the autopilot and auto throttle on very short final. And when manually flying an ILS approach (without auto throttle and autopilot) the DLC does a good job controlling the descent until you get closer to the runway. It is at this point where the problems arise as the DLC drastically restricts the ability to pitch up or down. Essentially locking the attitude of the aircraft. So if you start descending below glide path or climbing above glide path you essentially can only control that with power. The engines react slowly so if you over compensate (like I guess I have been doing) you really mess up the approach.