OHM TetherMFD v1.0

sputnik, I could kiss you. :bighug:
 
Anroalh12 said:
CTD when tethering an UMMU.
Click to expand...

Can anyone else verify this? I didn't test that. Is that using the other vessel as the source? Since I assume you can't use an MFD normally in UMMU. If you can, though (external MFD?) try it both ways.

If it's true, there's probably nothing I can do about it. I don't know what UMMU does; the source is, of course, not available. TetherMFD really only does 2 things; adds a force (which I doubt UMMU notices or has a problem with), and adds a negligible propellant tank and thruster to draw the tether as an "exhaust", which UMMU might be having a problem with.
 
I'm trying to use a pushback and an aircraft, but while scrolling through the ports, it only seems to show the COG and parent attachments for both vessels. Also, if it would'nt be too difficult, could you add the option of typing in the vessels ? It takes some time to scroll through, if you have a number of vessels. Thanks for this much needed update !!
 
Donamy said:
I'm trying to use a pushback and an aircraft, but while scrolling through the ports, it only seems to show the COG and parent attachments for both vessels. Also, if it would'nt be too difficult, could you add the option of typing in the vessels ? It takes some time to scroll through, if you have a number of vessels. Thanks for this much needed update !!
Click to expand...


It should cycle through CoG, docking ports, and TO CHILD attachments.

Also, the many defined keys of the older version were carefully left in place, so you can look up the keys and scroll only through attach points, or scroll BACKWARD through the list of vessels.

Yes, a key entry would be a nice enhancement, but I don't think we want it in place of the V+ key and we don't have room for one more.
(Is press-and-hold functionality a thing for Orbiter MFD developers? If not, can I figure out how to be the first?)
 
Anroalh12 said:
CTD when tethering an UMMU.
Click to expand...

sputnik said:
Can anyone else verify this? I didn't test that. Is that using the other vessel as the source? Since I assume you can't use an MFD normally in UMMU. If you can, though (external MFD?) try it both ways.

If it's true, there's probably nothing I can do about it. I don't know what UMMU does; the source is, of course, not available. TetherMFD really only does 2 things; adds a force (which I doubt UMMU notices or has a problem with), and adds a negligible propellant tank and thruster to draw the tether as an "exhaust", which UMMU might be having a problem with.
Click to expand...

I will confirm the opposite. Tether between an XR-2 (source) and a UMMU EVA (Target) worked perfectly with about a 15m 30N@1% tether, and it was spectacular. :thumbup: er, that was right up until I flung my EVA into a 30km higher orbit :facepalm:

This add-on is rather neat! :tiphat:
 
Great work. :cheers:

I'm having some difficulty with Gemini. Those astronauts are attached vessels and for some reason when the tether becomes fully extended it pushes the astronaut many KM back! Probably something I can solve by setting the N strenght. My guess is that the astronaut mass is not realistic (not a TetherMFD problem of course).
 
Last edited:
4throck said:
Great work. :cheers:

I'm having some difficulty with Gemini. Those astronauts are attached vessels and for some reason when the theater becomes fully extended it pushes the astronaut many KM back! Probably something I can solve by setting the N strenght. My guess is that the astronaut mass is not realistic (not a TetherMFD problem of course).
Click to expand...



You probably have too much force (actually stiffness) on the tether. You need to take it down to ~30N "@1%". (That's Newtons, not kiloNewtons.)

This will keep the acceleration an a 140 kg EVA around 0.02g, which will prevent it from being flung huge distances.
 
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Is there a reason to limit tether length to 10 000 km?

With a longer tether, one could make a space elevator...

BTW, having a blast with this. It makes Orbiter like a whole new sim for me with many new possibilities....

:thumbup:
 
Agreed !!
 
Very interesting. It's hard to maintain tension on the tether and prevent undesired spins (like mentioned in the readme).

Can the length/force of the tether be adjusted in smaller intervals? The MFD buttons for the length/force seem to increment/decrement the length/force in ca. 16% intervals.
 
Last edited:
wingnut said:
Very interesting. It's hard to maintain tension on the tether and prevent undesired spins (like mentioned in the readme).

Can the length/force of the tether be adjusted in smaller intervals? The MFD buttons for the length/force seem to increment/decrement the length/force in ca. 16% intervals.
Click to expand...

Tethering is not a great stabalizing technique, in space.
 
It worked quite well with the Space Shuttle Atlantis deploying a Carina satellite. But you have to do small corrections with the rotational RCS to maintain a reasonable attitude towards the second object.

I noticed that you can adjust the setup values in the .scn file which is fine for me.
 
WIP of a "non-rotating" skyhook concept: http://en.wikipedia.org/wiki/Skyhook_(structure)

You might need the stock bases upgrade. [ame="http://www.orbithangar.com/searchid.php?ID=6007"]Orbiter stock bases upgrade[/ame]

Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51982.4607744511
END_ENVIRONMENT

BEGIN_FOCUS
  Ship LowerEndpoint
END_FOCUS

BEGIN_CAMERA
  TARGET LowerEndpoint
  MODE Cockpit
  FOV 60.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE Surface
  SPDMODE 1
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE Tether MFD
  SetupTetherLength 10000000.00
  SetupTetherForce 20736.00
  SetupTargetIndex 1
  CurrentTether 0
  attach_type_v1 0
  attach_no_v1 -1
  attach_type_v2 0
  attach_no_v2 -1
  TetherData 0 CONNECT 1
  TetherData 0 Ship1 LowerEndpoint
  TetherData 0 Ship2 Anchor
  TetherData 0 Length 9202481.00
  TetherData 0 Force 20736.00
  TetherData 0 Attach1 0.00 0.00 0.00
  TetherData 0 Attach2 0.00 0.00 0.00
  TetherData 0 SpoolMode 0
  TetherData 0 ReelSpeed 0.00
  TetherData 1 CONNECT 0
  TetherData 2 CONNECT 0
  TetherData 3 CONNECT 0
  TetherData 4 CONNECT 0
  TetherData 5 CONNECT 0
  TetherData 6 CONNECT 0
  TetherData 7 CONNECT 0
END_MFD

BEGIN_SHIPS
GL-01:DeltaGlider
  STATUS Landed Earth
  BASE Kourou:1
  POS -52.7751338 5.2322676
  HEADING 22.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  NAVFREQ 402 94 0 0
  XPDR 0
  GEAR 1 1.0000
  AAP 0:0 0:0 0:0
END
Anchor:Anchor
  STATUS Orbiting Earth
  RPOS -13577823.62 3367663.09 -7763632.58
  RVEL 2640.444 1684.684 -3886.538
  AROT 0.00 -0.00 -0.00
  AFCMODE 7
  NAVFREQ 0 0
  XPDR 451
END
LowerEndpoint:Module2
  STATUS Orbiting Earth
  RPOS -5500874.48 1364444.54 -3145517.84
  RVEL 1077.088 683.150 -1576.019
  AROT -107.69 55.96 21.21
  AFCMODE 7
  PRPLEVEL 0:0.999956
  THLEVEL 0:1.000000 1:1.000000
  NAVFREQ 0 0
END
END_SHIPS

BEGIN_SpaceNetwork
END

BEGIN_ExtMFD
END

The idea is to take off in the delta glider and catch the node dangling at about 110km using a sub-orbital trajectory. If you can dock to it, awesome for you, but it is probably more practical to get as close as you can and shoot a second tether to it. Then, reel in the main tether to get up to a working altitude.

Two suggestions that I would have for the MFD:

-Have some way for the user to set the dampening ratio: http://en.wikipedia.org/wiki/Harmonic_oscillator#Damped_harmonic_oscillator

-Have the ability to confine the cone angle that the tether can be within from the source
(I'm noticing a lot of "yanking" causing rotation from grappling points that are off the center of gravity, since the tether is free to rotate 360 degrees)

Edit:

The mission is much easier if you find modue2.cfg in Config/vessels and add these lines:
EnableXPDR = TRUE
XPDR 452

This will give the lower endpoint node (aka the hook) a transponder to home in on. Here is an updated scenario:

Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51982.5172921397
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01
  MODE Cockpit
  FOV 60.00
END_CAMERA

BEGIN_HUD
  TYPE Docking
  NAV 0
END_HUD

BEGIN_MFD Left
  TYPE Map
  REF Earth
  OTARGET LowerEndpoint
  BTARGET Kourou
  ZOOM 4
  POS -1.54 0.00
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE Tether MFD
  SetupTetherLength 23.89
  SetupTetherForce 3348.98
  SetupTargetIndex 1
  CurrentTether 0
  attach_type_v1 0
  attach_no_v1 -1
  attach_type_v2 0
  attach_no_v2 -1
  TetherData 0 CONNECT 1
  TetherData 0 Ship1 LowerEndpoint
  TetherData 0 Ship2 Anchor
  TetherData 0 Length 9202481.00
  TetherData 0 Force 20736.00
  TetherData 0 Attach1 0.00 0.00 0.00
  TetherData 0 Attach2 0.00 0.00 0.00
  TetherData 0 SpoolMode 0
  TetherData 0 ReelSpeed 0.00
  TetherData 1 CONNECT 0
  TetherData 2 CONNECT 0
  TetherData 3 CONNECT 0
  TetherData 4 CONNECT 0
  TetherData 5 CONNECT 0
  TetherData 6 CONNECT 0
  TetherData 7 CONNECT 0
END_MFD

BEGIN_SHIPS
GL-01:DeltaGlider
  STATUS Landed Earth
  BASE Kourou:1
  POS -52.7751335 5.2322669
  HEADING 22.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  NAVFREQ 452 94 0 0
  XPDR 0
  GEAR 1 1.0000
  AAP 0:0 0:0 0:0
END
Anchor:Anchor
  STATUS Orbiting Earth
  RPOS 7811784.91 5552677.88 -12809703.54
  RVEL 4356.232 -970.029 2236.114
  AROT -0.00 0.00 0.00
  AFCMODE 7
  NAVFREQ 0 0
  XPDR 451
END
LowerEndpoint:Module2
  STATUS Orbiting Earth
  RPOS 3167270.16 2248988.95 -5188287.89
  RVEL 1763.395 -395.436 911.564
  AROT -107.69 55.96 21.21
  RCSMODE 2
  AFCMODE 7
  PRPLEVEL 0:0.999512
  THLEVEL 0:1.000000 1:1.000000
  NAVFREQ 0 0
  XPDR 452
END
END_SHIPS

BEGIN_SpaceNetwork
END

BEGIN_ExtMFD
END

Take off and fly south. Make a gradual left turn toward the east such that you have a heading of 90 degress when you get to the equator and you are directly behind the hook and moving toward it. Then climb and accelerate to intercept the hook from behind. Use your hove engines to muscle your way to the docking node. It is better to dock if you can.

Once docked, you will start to sink fast as the tether stretches under the increased weight. Reel the tether in FAST. Then adjust the reel rate to try to maintain a constant positive vertical velocity. It will get harder as you get closer to the anchor and orbital mechanics takes over. Just undock as soon as perigee is high enough.

If you get too close to the anchor, you may end up orbiting it by the tether, which is undesirable, so be careful.

It's a wildly impractical way of getting to orbit, but fun to do once in Orbiter, IMHO.

:cheers:
 
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Could the tether be shortened to 1m to simulate a pushback ?
Also, the COG and parent attachments are the only ones that work for me. The 1-0 don't work at all, per the manual description.
 
Donamy said:
Could the tether be shortened to 1m to simulate a pushback ?
Also, the COG and parent attachments are the only ones that work for me. The 1-0 don't work at all, per the manual description.
Click to expand...

Yes, I can break Matt's limits on the next release.

You mean...you can connect to CoG, and to a to parent attachment, but not to a docking port? That's weird.
 
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