Flight Question Landing DGIV to pads on Moon

[tsp]

Hi,

I reached to Moon, actually I managed to locate Brighton Beach too. No problem with that. But landing to the pad is terribly difficult. I watched David Courtney's landing tutorial below:

There, he holds his altitude with "hold alt AP" but I can't do that. When I press hold alt DGIV gains positive vertical velocity and jums to high altitudes of kilometers. Then I pass the target. When I disable this AP, this time holding altitude with manual hover control makes horizontal velocity uncontrollable.

Even after I do everything without the assistance of "hold alt AP", i.e., killing horizontal velocity and maintaining a fair altitude, I still can't land. Whether DG's vertical velocity increases too much and damages the DG or at the last second the glider bounces back to up while trying to lower that excessive vertical speed, then I lower it again and at the last minute it gains positive ver. speed when I try to slow down. This process repeats itself again and again like forever unless I land miraculously without damage.

What am I doing wrong? Isn't there a more practical way for moon landing. Please help.

 

[CaptainComic]

Here's an idea from my own lunar landing experiences:

Instead of using the altitude hold AP, use the Level Horizon AP (KillROT also helps) and switch thrusters to translation. Use the hover controls for gross vertical speed changes, and thrusters for fine control.

 

[Quick_Nick]

The DGIV has it's own hover autopilot. You can find it in the list of programs in the bottom panel or in the manual. It provides adjustable vertical velocity, which is generally more useful than altitude-holding.

 

[n122vu]

There is also a descent hold autopilot in the DGIV arsenal. Pick a vertical speed at which to descend, and no matter what you do to horizontal velocity, it will maintain that descent rate.

 

[Ripley]

The DG in that video is the default one, not the DG-IV.

 

[tsp]

Thank you guys. I didn't even realize it was a stock DG in the tutorial. So I found the hover AP and never used hold alt. It was a total success thanks to you. Here me landed to pad safely:



For other novices that may wonder how to do here is a list of what I did (assuming you have a nice stable lunar orbit aligned over Brighton Beach):

1- I used retro burns to slow down my horizontal speed when I come closer to Brighton Beach.

2- After I am really close (like 1.500 km) I used hover AP to adjust my altitude to 400 meters. Usage:

"PRO200SPEC7"

With numpad 2 and 8 you can adjust vertical velocity as you want without worrying your horizontal speed. To hold altitude adjust speed to zero

3- Aligning with landing pad is same with the tutorial video above, you can watch it. Use translation thrusters for alignment and adjusting horizontal speed. Gradually lower hor. speed as you approach and finally lower your hor. speed very near to zero when you are above landing pad.

4- Activate other hover AP for smooth landing. Type:

"PRO200SPEC8" or simply press "numpad 0"

After that DGIV will smothly land without any trouble.

Again I would like to thank all of you for notifiying me with this incredibly usefull tools of DGIV.

 

[Tommy]

The "stock" Altitude Hold AP does not always hold your current altitude - it trys to hold your altitude at the Apoapsis altitude (which is often higher than your current alt). There is a red line displayed on the altitude tape (in Surface MFD) which is the altitude the AP will try to hold. This mark my not be visible if it is "above" the range displayed.

As recommended above, the DGIV's autopilots are more usefull, and can hold a set descent rate making landing much easier.

 

[PhantomCruiser]

If I remember correctly, Go Play In Space has a chapter where you launch from Brighton Beach, do a single orbit and recover again at the Beach. I did that over and over again until I could nearly get it right in my sleep.

 

[Cras]

I use a plethora of MFDs to get my ship onto a landing pad. I have a thing for doing stuff as fuel efficient as possible. Not something that is exactly neccessary, but its just a goal I like to try and achieve.

I use BaseSync, DVTools, IMFD, and HoverMFD to get me to the pad Those MFDs have a bit of a learning curve...well basesync is pretty straight forward, but the others require a bit of experience to really get right. Go Play in Space is always a lovely place to start and get a grip over the basics. Then you can see where you do better, and how the many MFDs that have been made by the good people here can help you out in doing that. There really is no one right way to do it. I have written two totally different procedures with their own profiles to get me from lunar orbit to a pad on the surface. Figuring out the best way to do it, or the most comfortable way to do it that suits your style, is half the fun of Orbiter. It is for me anyway.

 

[tsp]

The "stock" Altitude Hold AP does not always hold your current altitude - it trys to hold your altitude at the Apoapsis altitude (which is often higher than your current alt). There is a red line displayed on the altitude tape (in Surface MFD) which is the altitude the AP will try to hold. This mark my not be visible if it is "above" the range displayed.

As recommended above, the DGIV's autopilots are more usefull, and can hold a set descent rate making landing much easier.

I should have known. I thought my version is broken when it begin to climb up. Thanks for the tip.

---------- Post added at 05:38 PM ---------- Previous post was at 05:32 PM ----------

If I remember correctly, Go Play In Space has a chapter where you launch from Brighton Beach, do a single orbit and recover again at the Beach. I did that over and over again until I could nearly get it right in my sleep.

Well, actually I did it manually so many times over and over again without knowing there is an AP that I was literally trying to do it right in my sleep while dreaming :lol:.

---------- Post added at 05:49 PM ---------- Previous post was at 05:38 PM ----------

I use a plethora of MFDs to get my ship onto a landing pad. I have a thing for doing stuff as fuel efficient as possible. Not something that is exactly neccessary, but its just a goal I like to try and achieve.

I use BaseSync, DVTools, IMFD, and HoverMFD to get me to the pad Those MFDs have a bit of a learning curve...well basesync is pretty straight forward, but the others require a bit of experience to really get right. Go Play in Space is always a lovely place to start and get a grip over the basics. Then you can see where you do better, and how the many MFDs that have been made by the good people here can help you out in doing that. There really is no one right way to do it. I have written two totally different procedures with their own profiles to get me from lunar orbit to a pad on the surface. Figuring out the best way to do it, or the most comfortable way to do it that suits your style, is half the fun of Orbiter. It is for me anyway.

I totally agree with you. This freedom of availability is the best feature of Orbiter. But still, I should complete the basics before trying more challenging ways and advanced MFDs. As PhantomCruiser also mentioned Go Play in Space is a good way to learn I suppose. I will take a look at that.