Flight Question DG4 docking to ISS

[jimi]

hi all
Is it possible to dock the DG4 to ISS using only the keypad?
Every time, at the last quarter of my final orbit (after following the video tutorial) I can never seem to be able to control the DG4 enough to dock - I always over-shoot, or the docking guide boxes are on the far side of the ISS and I have to pass ISS and try and turn DG4. I have been struggling with this for at least 10-12 hours and can never get it to work. Orbit has been syncd and planes have been aligned perfectly - but I can never dock. One thing I do notice is that according to the tutorial, I should be able to see sunrise once I get to within a short distance from ISS - but in all my attempts I can't see it.
Is docking DG4 to ISS possible using only a keypad (no joystick)
Thanks in advance

Frustrated

 

[Pyromaniac605]

Start lining up as soon as you have visual contact with the ISS, everything in space, especially rendevouz requires you to be slow and take your time to get it right.

Also, try reading Go Play in Space, the tutorial in there might help you a bit more

 

[Wishbone]

Keypadding is your friend. Also try starting AttitudeRCS MFD in the dock mode. You'll be automatically aligned rotation-wise and the only thing that would remain - simply using translational thrusters to dock.

 

[jimi]

Wishbone - forgive my ignorance - but what's "AttitudeRCS MFD in the dock mode". I have docking MFD up, HUD synced with the MFD but can't find anything called "AttitudeRCS MFD in the dock mode"
thanks in advance

 

[Carmen A]

Yes, keyboard control is no obstacle to docking. You just got to be smooth and remember you can't pull the brakes to stop instantly in space. So fly smoothly and predict your trajectory in advance.

Small burns may not look as glam as a fully powered interception, deceleration and docking sequence but will prevent you from overshooting and having to use main engines to correct!

Here's how I managed a "landing" on a ship without a suitable docking port:

 

[Wishbone]

Enable ScriptMFD in the modules tab of the Launchpad. You'll see Attitude RCS in the list of MFDs when the scenario is loaded. Your NAV1 should be tuned to the IDS frequency of the dock, press DCK, press ACT and you're Ok. Just remember to press CNC after docking.

 

[orbitingpluto]

You might want to use the fine RCS controls-hold Ctrl when you hit the RCS buttons for the fine settings. Less thrust is used making it easier to keep movement slow and gentle.

 

[jimi]

OK - last silly question (I hope) - how do I find the IDS frequency of the dock?

 

[orb]

how do I find the IDS frequency of the dock?

You can get IDS frequencies from "Object info..." dialog (you can select it from F4 menu). But you don't need those frequencies. You can select directly the target docking port (TGT button) in the Docking MFD, and then transfer it to Docking HUD.

 

[orbitingpluto]

with the menu that brought up with F4, there is a tab that says Object Info, or something like that. The IDS frequency is there along with many other useful bits of info. Remember to switch it out of camera target though, because object info defaults to showing the info from the current camera target; in most cases that would be your ship.

Edit:Ninja'd by Orb

 

[Wishbone]

Re: simple ways for finding out frequencies - 1. Object info in the Ctrl-F4 menu. or 2. Install NAVSET addon ([ame="http://www.orbithangar.com/searchid.php?ID=3631"]NAVSET[/ame]).

 

[jimi]

OK - even though I follow the instructions, and take my time, my scenario is still trying to dock me on the dark side. Anyone got any ideas?

 

[orbitingpluto]

You could rely on the Dock mfd and go for a dock anyway, or keep a set distance from the ISS till you get to the day side. You can use the autopilot on the DG4 to keep the distance from you. Get to a good spot and use the 'null relative velocities' autopilot. You have to use the flight computer in the bottom panel to activate it, and the checklists also on the bottom panel should have the info on how to do that.

 

[jimi]

Impossible!

this thing is impossible - I take my time, but when ever I just about line myself up with the guide squares of ISS docking, they rotate away from me and I spend all my time trying to catch up with them. Am I missing something? Is there a step I've missed somewhere that makes me align with ISS rotation? Is there an ISS Rotation? I take my time getting there, line everything up, slow down and try an coast into the guide squares, with my closing speed around 1, I hit the first square, then ISS disappears and my closing speed is negative (ISS is faster), so I speed up to try and catch it, only to find that ISS dock has rotated around!
Is there something I'm missing? some sort of add-on? I have approx 300 pages of manuals and stuff next to me, following the tutorial video to the letter but no go.

 

[PeterRoss]

ISS must not rotate at all. You will never dock to space station if it rotates (well, except of one particular case which is not your case definitely). Try to kill rotation of ISS in the Angular Velocity window of its properties in Scenario Editor. Maybe you can focus on ISS and use KillRot autopilot, I don't have much experience with ISS, never use it in my scenarios, but I think it have to be controllable.

---------- Post added at 08:12 PM ---------- Previous post was at 08:09 PM ----------

You can also post here your scenario file text for us to try it and see why this problem happens.

 

[jimi]

OK - I'm just using the stock standard 'Landed KCS Departure to ISS' scenario that came with my download of DG4 stuff - I haven't modified anything. I haven't changed anything, so if it's not meant to be rotating then it probably isn't, which leads me to ponder - why, when I take my time, does the damn thing seem to be 'rotating' away from me?
I'm about ready to ditch this whole orbiter thing, but this has become a bit of a personal challenge now, but no matter how many attempts I make at this (from launch to attempted dock) I always end up with the same problem (as described re seemingly rotating ISS). Last thing - a couple of times now I've been at the last stages of the final orbit, expecting to see ISS in front of me, only to have it approach me from behind....any ideas anyone?

 

[PeterRoss]

Step one: don't worry Every problem can be solved, in most cases its source is some minor mistake or misunderstanding or some other unnoticeable thing you'll be laughing at when it will come up.

Step two: save your flight state at the stage when you're near the ISS and post it here and we will say you what's your problem. You'll see it is easy to solve when we have the full information.

---------- Post added at 08:45 PM ---------- Previous post was at 08:32 PM ----------

By the way, station approaching you from behind during rendezvous is quite a common case, this just means that your velocity is less than station's velocity. I repeat, this is normal situation.

---------- Post added at 09:15 PM ---------- Previous post was at 08:45 PM ----------

I've cheked this scenario - everything seems well there. You have to know that every object on orbit is getting some 'random' rotation if 'Nonspherical gravity sources' is checked in the Launchpad at the Property tab. So ISS will rotate anyway. You have to select ISS as focus vessel (press F3 and select ISS from the list), engage KillRotation autopilot by pressing 5 on the numpad or clicking the KILLROT button in the middle of the bottom part of glass cockpit, and then just switch back to your Deltaglider (F3) - ISS will stop its rotation. Don't know why there is nothing said about it in tutorials you're using - it is common procedure, you ALWAYS have to stop rotation of both vessels before docking.

 

[jimi]

ok - still no go. i turn off the ISS rotation as instructed but i keep going through the guide rectangles.
here is mi last scc file save - is someone able to have a look at it and let me know if i've missed anything?
====START====
BEGIN_DESC
Orbiter saved state at T = 10861
END_DESC

BEGIN_ENVIRONMENT
System Sol
Date MJD 60247.0358650635
END_ENVIRONMENT

BEGIN_FOCUS
Ship GL-01
END_FOCUS

BEGIN_CAMERA
TARGET GL-01
MODE Cockpit
FOV 50.00
END_CAMERA

BEGIN_HUD
TYPE Docking
REF ISS 0
END_HUD

BEGIN_MFD Left
TYPE OSync
TARGET ISS
MODE Sh apoapsis
LISTLEN 5
END_MFD

BEGIN_MFD Right
TYPE Docking
TARGET ISS 0
END_MFD

BEGIN_PANEL
END_PANEL

BEGIN_SHIPS
ISSrojectAlpha_ISS
STATUS Orbiting Earth
RPOS -6289926.14 2308243.36 567511.21
RVEL 2330.177 6929.427 -2407.814
AROT 110.00 -10.00 80.00
AFCMODE 7
PRPLEVEL 0:1.000000
IDS 0:588 100 1:586 100 2:584 100 3:582 100 4:580 100
NAVFREQ 0 0
XPDR 466
END
Mir:Mir
STATUS Orbiting Earth
RPOS -1287139.04 398553.08 6518739.31
RVEL -7592.495 -91.831 -1490.113
AROT 0.00 -45.00 90.00
AFCMODE 7
IDS 0:540 100 1:542 100 2:544 100
XPDR 482
END
Luna-OB1:Wheel
STATUS Orbiting Moon
RPOS 1404251.48 1746086.16 1680.40
RVEL -1152.671 926.840 1.478
AROT 0.00 -0.00 121.03
VROT 0.00 0.00 10.00
AFCMODE 7
IDS 0:560 100 1:564 100
XPDR 494
END
GL-01eltaGliderIV
STATUS Orbiting Earth
RPOS -6495354.55 1529733.22 827042.56
RVEL 1406.749 7155.821 -2292.891
AROT 107.72 -10.34 169.26
VROT -0.00 0.07 -0.00
RCSMODE 2
PRPLEVEL 0:0.396333 1:0.907664 2:0.983333
IDS 0:45 100
NAVFREQ 588 524
XPDR 0
;-------------------------- Skin parameters must contain directory name of skin (without space)
MeshSkin Mining
;-------------------------- Cargo payload must contain name of config file or "none".(see doc)
CargoPayload none
NOSECONE 0 0.00
GEAR 0 0.00
AllDoorsState 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0 0.00
But1Cockpit 0 0 0 2 2 2 0 2 2 2 2 2 2 2 2 1 1 0 1 1 1 3
But2Cockpit 0 0 0 0 0 0 0 0 2 2 2 2 2 0 50 0 0 0 2 1 0 0
TransEffect 0
LifeBut1State 0 2 1 2 1 2 2 2 2 2 2 2 2 0 0
LevelBatt 100.0002
Emergency_power 10000.0000
VoltageStartBus 0.0000
VoltageGen1 96.2820
VoltageGen2 96.2819
VoltageGenBus 96.0000
O2tankALevel 94.8512
N2tankALevel 100.0000
O2tankBLevel 100.0000
N2tankBLevel 100.0000
CabinO2Level 21.3885
CabinCO2Level 600.0000
CabinTempLevel 21.2000
CabinPressure 14.7000
CabinMoistLevel 36.0000
CabinDustLevel 0.0001
CabinO2Setting 21.4000
CabinTempSetting 21.2000
CabinPressSetting 14.7000
AntennaTarget no_target
O2ConsumptionSetting 1
FuelConsumptionSetting 1
MainenginePower 1
;------------------Crew parameters UMMUCREW Function-Name-Age-CardiacPulse-WeightKg (fonction of Pilot must be: Capt)
NoOneOnBoard 0
NoPilotOnBoard 0
UMMUCREW Capt-Christopher_Coles-47-60-70
UMMUCREW Spe-Burton_Lambert-22-66-78
UMMUCREW Ast-Daniel_Gecker-33-72-75
UMMUCREW Eng-Bradley_Banister-55-72-79
UMMUCREW Spe-Bradley_Banister-36-65-82
FailGearFailure 0
FailGearCollapse 0
FailLeftMainEngine 0
FailRightMainEngine 0
FailHoverEngine 0
FailRcs 0
FailSurfaceControl 0
FailComputer 0
FailComputerBlueScreen 0
FailAutopilot 0
FailExtRadiator 0
FailAirbrake 0
FailNoseCone 0
FailCanopy 0
FailAntenna 0
FailLeftTurbo 0
FailRightTurbo 0
FailCargoDoor 0
SpacesuitTimer 0
END
END_SHIPS

====END===

 

[PeterRoss]

I've made a succesful docking using your scenario. I'll be explaining all the stages of my flight in details most of which you already know, I just don't want to miss some details.


First of all, your approach is just perfect. It brings you within 1.7 km from ISS in the closeset approach point - it's really good. I would advise you only to use Intersect 1 or Intersect 2 as a reference point at the SynchOrbit MFD since you can be sure that in these points both yours and your target's orbits will intersect (considering they are intersecting) and your approach will be as close as possible. My relative (to ISS) speed in the closest approach point was something like 56 m/s - it is nothing for DGIV engines to change. You have to select any of ISS docking ports in your DockingMFD and press HUD button on the MFD - your HUD will change mode to Docking. Square marker shows the current target position, circle marker with cross inside and V above it shows your relative velocity vector with numerical value of it, and circle marker with dot inside and -V above is even more important - this vector shows direction of your burn needed to get your relative velocity to zero. And that's exactly what you have to do in the closest approach point - direct DGIV right into the circle marker with dot and make a burn with main engines (you can also use retro engines - you'll just have to direct DGIV into circle with cross marker). When the numerical value above the marker is zero or close enough to it you may care no more about orbits and synchronization and stuff and just consider yourself flying around ISS. Simply direct your vessel somewhere near it - into the approach square closest or second closest to ISS for example - and get some speed. When you've arrived into the approach corridor (and brought your relative speed to zero once more) it's good moment to kill ISS rotation even if you've done that before. Now you have to direct your relative velocity vector into docking port - I'm using TranslateRCS mode to do this - and then just dock using DockingMFD. The docking process is a game itself where you have to align your approach vector and rotation with station docking port's vector and rotation. I can explain this too in details if you need.

 

[jimi]

PeterRoss - Many thanks - I'll have to digest what you've put here and try and remember it - I don't have a printer to print it out so may have to consider writing it out. Anyways - I'll give it a shot and let you know

---------- Post added at 07:19 AM ---------- Previous post was at 07:18 AM ----------

oh - and the damn sim won't even let me ram ISS out of frustration - no satisfaction there, no explosions or anything.....it just passes straight through it

---------- Post added at 07:39 AM ---------- Previous post was at 07:19 AM ----------

first silly question - when I select Intersect 1 or Intersect 2 and set target to ISS, I get 'No Intersection'.......