[1.3](Jan28/17) Landing Aid: Kill your horizontal velocity to land (Now optionally using RCS)

[FortyCaliber]

It should be GameData\Diazo\RCSLandAid i.e you went one folder too deep.

Thanks. I didn't think the mods were that sensitive to folder structure.

[Diazo]

In this case it's the button texture that requires that specific directory. I've hard-coded the mod to look for the button texture at GameData\Diazo\RCSLandAid so it could not find the button to display when it was at GameData\RCSLandAid.

I'll give my install instructions a once-over to make that clearer.

D.

[Schilcote]

It'd also be great if we could use RCS to deal with vert vel too, for zero-altitude spaceplane landings on Minmus.

[jordanjay29]

Can't believe I overlooked this mod. What a great concept, I shall have to try this out in my new 0.24 setup.

[Diazo]

@jordanjay29: Glad to hear you are going to try this out.

@Schilcote: When this mod is engaged, it does not lock out the keyboard controls for the RCS. You should be able to use the Up/Down RCS to land while allowing the mod to keep you above the same point on the ground. (Note I have not actually tested this, but it should work.)

D.

[Diazo]

KSP Version 0.25 Compatibility

The latest version of this mod is compatible with KSP 0.25 and you do not need to re-download it if you already have this version.

D.

[Schilcote]

@Schilcote: When this mod is engaged, it does not lock out the keyboard controls for the RCS. You should be able to use the Up/Down RCS to land while allowing the mod to keep you above the same point on the ground. (Note I have not actually tested this, but it should work.)

That's not quite what I meant.

The idea is that you can land on, say, Minmus much like you would land a plane on Kerbin; use the wings to kill your vertical velocity, then use your wheels to kill your horizontal velocity essentially for free. Trouble is, wings don't work on Minmus, so you've got to use engines or RCS thrusters. I'm saying it'd be very handy if your mod could automatically control descent speed while ignoring horizontal velocity.

[Diazo]

@Shilcote: Okay, I'm now not sure what you are asking for.

First, this mod is designed to control horizontal speed only. That is because I intend it to be used with my Vertical Velocity mod which controls vertical speed.

The vast majority of landings will be in higher gravity environments where the RCS does not have enough thrust to land you so the main engines are active to bring you down safely.

In very low gravity environments such as Minmus where RCS does provide enough vertical thrust to land, the Vertical Velocity mod will be off as the main engines are not being used, but that means you can use the Up/Down RCS manually to land as this mod (RCSLandAid) does not prevent those RCS thrusters from firing.

As the gravity is so low and the acceleration provided by RCS is so gradual, the "ham-fistedness" of the controls that drove me to write these mods in the first place does not exist and landing the spaceplane on RCS should be straight forward.

Except from your post it sounds like it is not. What exactly is the flight profile you are looking for here? I can't picture what you are trying to do, notably, what exactly does "zero-altitude spaceplane landing" mean?

D.

[JeffreyCor]

I tried this before but never could get the arrow to come up for selecting where to hover over. I'll give it another try and see if I have better luck. The precision for hover / landing position sounds perfect for flying cranes and/or base building

[Diazo]

Pretty much the reason I added the "hover over this location" feature was for exactly that reason, to precision build bases and landing skycranes.

The only two reasons it might not be coming up are that you are outside the 2000m limit, where the point on the terrain you are trying to click is farther then 2000m from your active vessel. The other catch is to make sure you are right-clicking, left-clicking enables velocity canceling mode.

Watch the color of the icon on the toolbar to tell you what mode it thinks it is in, red means you have entered "hover over this location" mode.

As always, toss up any issues you have and I'll work them out for you.

D.

[JeffreyCor]

I've noticed when using this it seems to keep applying RCS thrust until it reaches the mark, and then reverses thrust. As a result the ship has amassed so much speed it overshoots the target. Maybe a speed limit to prevent as much of a problem, or settable speed on so ships with more mass can be set to a lower maximum speed? Just some thoughts for what might be the simplest solution.

[Diazo]

As I did not know how to get effective thrust from an RCS block like I do an engine, so it already works on the basis of a speed limit.

I thought I'd restricted it low enough but it sounds like not.

And in fact upon checking my code it looks like I forgot the "slow down to stop at a specific spot" logic.

Bleh, it's one line of code that I'll throw in as soon as I get home from work.

D.

[JeffreyCor]

At least it wasn't user error or my part Looking forward to when you get a chance to update it and if you're in the US Happy Thanksgiving.

[Diazo]

Version 1.3

Download here.

-Revise move to point code to make more sense.

Now, vessel will try to accelerate/deccelerate at 0.1m/s and it will brake pre-emtively to try and stop at the target point without bouncing back and forth.

As always, let me know how it goes.

D.

[drtedastro]

Excellent... Many thanks Diazo.....

Cheers.

[JeffreyCor]

Whoo hoo!! Yeay Diazo!

[Diazo]

Just bringing a conversation over from my Vertical Velocity mod thread about using the engine gimbals to increase the available sideways thrust.

While controlling the gimbals themselves will not work as that would make your thrust off-center and tip your craft over, it has made me look at tipping the entire craft deliberately with the SAS system to use the main engines to get horizontal thrust.

If possible, this would overcome the biggest limitation of this mod where RCS thrusters just don't have a lot of thrust.

D.

[JeffreyCor]

It would be tricky especially with heavy craft to keep them from losing control like MJ does when set to kill horizontal velocity while maintaining vertical speed. Have lost too many ships with that tipping it wildly correcting itself. Maybe a limitation on tilt angle for a max of 5-10 degrees or so off vertical would prevent that problem

[BudgetHedgehog]

Yeah, a limit would be very nice - I too have lost many ships from MJ swinging it near horizontal to kill a tiny bit of speed.

[Diazo]

Certainly there would be a hard limit.

At the moment, I'm still thinking keep the 5m/s max speed with a 5 degree max tilt. That would give a max horizontal acceleration of 0.85m/s^2 on Kerbin.

The downside of this method is that the strength of the gravity well affects your horizontal speed because your vertical "acceleration" is equal to a set percentage of the force of gravity to keep your ship hovering in the air. At 5 degrees this is just under 9% which is a reasonable 0.85m/s^2 on Kerbin, but on Moho which is 2.7m/s^2 gravity, 5 degrees would only be 0.2m/s^2 of sideways acceleration.

Maybe I'll have to go to 10 degrees max? That would be 0.5m/s^2 on Moho.

Testing required to confirm this is all possible, but it's looking feasible at this point.

D.

[Diazo]

Version 2.0

And the version using vessel tipping is out.

The mod no longer uses RCS but instead will tip the vessel as required in order to control it's horizontal velocity. If you do enable RCS, the SAS system will use the RCS blocks to turn the vessel faster and smoother, but as long as you have enough SAS torque, the mod will be happy.

Note this mod specifically controls horizontal speed only and requires the main engines to be on to have any effect so a mod to hover in place is recommended to accomplish this.

Let me know how it goes, I suspect I will need to tweak the move-to-point code again as it did overshoot by quite a bit a few times.

D.

[drtedastro]

I may be trying to download too soon after you upload. Download is giving 404 error...

Thanks.

[Diazo]

Bleh, link is fixed. I forgot a /

Sorry about that.

D.

[drtedastro]

Hey, no problem'o.....

great stuff, as you always do.

Cheers.

[Diazo]

Version 2.1

-KSP 0.90 Compatibility fix.

No functionality changes visible to the player.

The ability for Kerbals to be pilots has changed how the underlying code around vessel SAS works and version 2.1 of the mod updates to account for them.

As such, upgrading to version 2.1 is required, version 2.0 of this mod will not even load on KSP 0.90.

In all the tests I did the mod worked great. There was perhaps more bouncing back and forth then I liked in the move-to-point mode, but it works as is and I need to get my other mods up and running before taking another look at the math this mod uses.

Let me know how your own tests go.

D.