AFCS? DAFCS? DASH? LCT? Explained Below

[47_Driver]

35 minutes ago, adrift_foolish1 said:

Just wanted to make an attempt to clear up a few things.

1. The Dash Acronym is Differential Airspeed Hold.

2. With a functioning DASH, airspeed is mostly a function of longitudinal stick position. The aircraft is rigged to fly at a steady 100 knots when the stick is at 1" forward. There is no forward/aft balancing act required to hold airspeed. Increasing forward stick always results in increasing forward airspeed, also known as positive stick gradient.

3. WITHOUT the dash, one of the things lost is that positive stick gradient. Now when you've accelerated to your desired airspeed, you have to move the cyclic aft to some position to maintain that airspeed, generally farther aft than the hovering stick position.

4. DAFCS is an entire system replacement for the older, analog AFCS. AFCS was not installed on any F model.

 

Took me this long to realize I accidentally typed Digital instead of Differential when describing the DASH, oops.

[Fuerte]

2 hours ago, adrift_foolish1 said:

2. With a functioning DASH, airspeed is mostly a function of longitudinal stick position. The aircraft is rigged to fly at a steady 100 knots when the stick is at 1" forward. There is no forward/aft balancing act required to hold airspeed. Increasing forward stick always results in increasing forward airspeed, also known as positive stick gradient.

Now that makes more sense, thank you.

[dahui]

3 hours ago, adrift_foolish1 said:

 

4. DAFCS is an entire system replacement for the older, analog AFCS. AFCS was not installed on any F model.

 

so in the F Model you needed to trim manually (AFT Stick Position as mentioned) to maintain Airspeed?

[MagicSlave]

so in the F Model you needed to trim manually (AFT Stick Position as mentioned) to maintain Airspeed?

No. F does have DASH. DASH has nothing to do with DAFCS/AFCS. They are separate systems. You may want to read the first post of this thread for clarification.

Sent from my FP4 using Tapatalk

[SteelPig]

So can we simply say that cyclic forward does not set the desired speed, but rather the desired acceleration? And when the desired speed is reached, can I set the cyclic to neutral again?

[Yo-Yo]

4 hours ago, SteelPig said:

So can we simply say that cyclic forward does not set the desired speed, but rather the desired acceleration? And when the desired speed is reached, can I set the cyclic to neutral again?

No, we can not. DASH is a functional analog of natural stable airplane where the trim speed is a function of the stick position.  Without DASH it resembles a plane with neutral stability, where any speed requires almost the same stick position. The way you described control algorithm is the second case.

[Rogue Trooper]

Excellent video 47Driver, thank you for that.

 

[Semaphore]

I am unsuire if i am enjoying the CH-47F since update with DASH and LCT...  I am finding landing much more difficult asless able to bleed off speed on approach with LCT acting as they do keeping the fuselage level. 

Is this a side effect of not having DAFCS as only option i finds is to disengage LCT as feel i can pick up the nose to flair on apprach and then touch down like normal helicopters...

What are others thoughts on this?

 

Also... Bob's piloting skills are much more poor since introduction of DASH and LCT... flying he porpoises along with the nose going up and down, the cyclic dancing about.  Basically, Bob seems to have gotten worse at flying?

[ChrisUK27]

On 11/6/2024 at 3:33 PM, Semaphore said:

I am unsuire if i am enjoying the CH-47F since update with DASH and LCT...  I am finding landing much more difficult asless able to bleed off speed on approach with LCT acting as they do keeping the fuselage level. 

Is this a side effect of not having DAFCS as only option i finds is to disengage LCT as feel i can pick up the nose to flair on apprach and then touch down like normal helicopters...

What are others thoughts on this?

 

Also... Bob's piloting skills are much more poor since introduction of DASH and LCT... flying he porpoises along with the nose going up and down, the cyclic dancing about.  Basically, Bob seems to have gotten worse at flying?

What you'll find for a straight in approach is that as you pull back and the DASH, LCTA's motor you'll reset the cyclic to the middle then pull back again. If you want to stop quickly I find a good old handbrake turn (quick stop) does the trick, sometimes you may balloon up a touch if you misjudge it, but you can knock the speed off pretty quick.

[Bigity]

Anyone have a summary of what the new trim options are? 

[Raven (Elysian Angel)]

1 hour ago, Bigity said:

Anyone have a summary of what the new trim options are? 

As far as I can tell it's all related to the trim hat on the cyclic, and the CD REL button actually works as it should now (as a force trim release).
Sadly there is no separate option yet for pedal trim in the Special Options...

Edited December 24, 2024 by Raven (Elysian Angel)
I sinned against the helicopter gods 🤭

[Bigity]

10 minutes ago, Raven (Elysian Angel) said:

As far as I can tell it's all related to the trim hat on the cyclic, and the CD REL button actually works as it should now (as a force trim release).
Sadly there is no separate option yet for rudder trim in the Special Options...

Still no separate pedal trim option? For pete's sake 

[ST0RM]

With the new changes from this week's update, how are we to use the trim now? Hat positions only? I see a new bind for the probes, but unsure if they're working and if so, how they are used. I recall they are automatic, but figure it's worth an ask. Thanks

[Zentaos]

gahhh!!...getting lost in the updates juggling all my sims...

now I need to get this set up and working again after updates to DCS and the MOZA Cockpit software for my cyclic profile.

[Dragon1-1]

On 8/31/2024 at 3:54 AM, 47_Driver said:

47 has always had at least a basic SAS or Stability Augmentation System. Just too difficult to fly without it. The 46 would have had to have had very similar systems, yes. All tandem rotors will, as these systems overcome the inherent lack of stability of a tandem rotor design.

Do you know how the Flying Banana handled this? Looking at the pics, it doesn't seem to have much in way of flight assists, what with being a 50s design. Then again, perhaps it was simply very hard to fly, not exactly unusual with helos of the time.

[47_Driver]

On 3/12/2025 at 3:22 PM, Dragon1-1 said:

Do you know how the Flying Banana handled this? Looking at the pics, it doesn't seem to have much in way of flight assists, what with being a 50s design. Then again, perhaps it was simply very hard to fly, not exactly unusual with helos of the time.

No idea, but I'd wager to guess that thing was pretty hard to fly lol

[Marsvinet]

On 3/12/2025 at 10:22 PM, Dragon1-1 said:

Do you know how the Flying Banana handled this? Looking at the pics, it doesn't seem to have much in way of flight assists, what with being a 50s design. Then again, perhaps it was simply very hard to fly, not exactly unusual with helos of the time.

I know most of the later versions had an autopilot, H-21B and C, but the earliest A version? Don't think it did. It does have those stabilizing surfaces on the rear pylon, but I doubt they were enough.

[Chipwich]

On 12/24/2024 at 4:50 PM, Bigity said:

Still no separate pedal trim option? For pete's sake 

I'm not sure that we need it with AFCS. Watching @47_Driver's latest video, Easy Mode Activated, he demonstrates turns with feet on the floor as well as forward flight with a crosswind.  In the latter case, the AFCS keeps the ball centered by automatically yawing the airframe into the wind, while the flight path is straight. It will be hard for me to do this, flying with my feet on the pedals feeling the natural thing to do.  But that's probably more of a habit than a need once the system gets fleshed out.

Edited March 25 by Chipwich