Air to Air Refueling Like a Boss

[V8jester]

Air to Air Refueling Like a Boss

  

 

This tutorial is meant to provide you with all the tips and tricks I've learned from other forum members, as well as new ideas I've been working on myself.

 

Some terms you'll need to know before you begin are:

The flying gas station is called the Tanker. The hard line from the tail of the Tanker is called a Flying Boom. A flexible hose with a cone at the end is called a Drogue Line. The plane being filled is called the Receiver. And lastly the ridgid snorkel on a Receiver, used to capture the Drogue. Is called the Probe.

 

 

 

Probe and Drogue - In the real world this came first (kinda) and is in some ways more forgiving for beginners to engage the Drogue with a Receiver plane mounted Probe. The downside is if you bump the Drogue it'll flop all over the place until aero forces stabilize it again. This method provides a flexible line connecting both planes to allow a larger bubble of movement while refueling. In KSP this is the easier way to dock two or more planes together but if performed in an "Undocked" state. Which allows independent control of each plane. (You will most definitely crash if both planes are "Docked") There is no ability to transfer fuel between the two planes when using a KAS winch in "Undocked Mode". This is great for cinematics and screenshots, just not for actual fuel transfer.

 

Additional Info / Pictures Of The Assemblies:

Spoiler

Below are some examples of the equipment I constructed for Probe and Drogue.

 

Drogue in it's closed state

Parts / Mods used: Tweakscale, Squad Airbrakes, Squad Simple Fins, KAS Port, B9 Lights, Custom Fuel port

 

Drogue in it's open state

Remember if the Drogue is connected to the KAS winch in "Undocked" mode by a Kerbal. You will not have the ability to control the airbrakes or lights. So open the airbrakes and turn on the lights before reconnecting in "Undocked" mode.

 

Receiver Mounted Probe

Parts / Mods used: Tweakscale, RKE Kanadarm, IR / IR Rework, Custom Fuel Port, Custom Kanadarm cfg Patch

 

 

 

 

Flying Boom - This is a rigid connection between both planes. In the real world this was developed second. In order to transfer more fuel in a shorter period of time. In KSP this is the most functional as this is the best way to remain in control while actually transferring fuel. Once you "Dock" both planes together they will fly as a single plane. In which case, most of your pitch control will come from the Receiver plane. So often the connection of the fragile boom needs to be reinforced by Quantum Struts, immediately after docking has occurred. If you don't reinforce the connection immediately after docking, the planes can twist apart within seconds depending on the design of the planes and the boom.

 

Additional Info / Pictures Of The Assemblies:

Spoiler

Below are some examples of the equipment I constructed for a Flying Boom system.

 

Parts / Mods used: Tweakscale, RKE Kanadarm Tubes, IR / IR Rework, B9 P-wings, B9 Aerospace, Procedural Parts, Custom Fuel Port

Note the Quantum strut aimed from the B9 Intake, back up the length of the Kanadarm tube to the Tanker, in between the two B9 P-wings. (Red lines are Quantum Struts) It's used to reinforce the flying boom once it's lowered / deployed. I used the B9 Intake like a chassis where everything mounts to it. It's the backbone for the entire structure of the Boom. Hidden inside the RKE Tube are 2 IR Rework Extendatrons to extend or retract the final length of the Boom (The IR Structural Tube with the custom port) As well as 2 IR rework Rotatrons to change the angle of the boom control fins as it moves up or down.

 

Close up, of the Quantum Struts used to reinforce everything after docking.

Note: the single Quantum Strut inside the B9 intake. It's holding the IR Structural Tube to the intake, which in turn is connected back to the Tanker with another Quantum Strut. (I used the B9 Intake as the back bone, as it has physics enabled).

 

 

 

V-22 Osprey, Refueling from a KC-10 Extender

 

And Now, Onto The Tutorial

 

The mods I suggest using to perform this task are RKE Kanadarm for the Flying Boom, and also for the Probe tubes. The reason these are the best parts to use for the tubes is they are physics-less and don't flex / separate under loads. KAS if you are using the Probe and Drogue method. IR / IR Rework if you want to be able to move anything. Also MechJeb is recommended as it makes aligning the two planes much easier - Using "Spaceplane Guidance" If you're looking for a scale appearance, my custom cfg's to rescale as well as increase the force and range of the magnets in a Squad Docking Port Jr. And as a bonus, the B9 Aerospace Shielded Docking Port if you have B9 installed. If you use RKE Kanadarm tubes or any other physics-less parts. Be sure you never attach a Quantum Strut directly to or from a physics-less part. It will lock the craft in place during flight, and cause all kinds of Kraken like behavior. Instead attach a physics enabled part to the RKE Tubes then the Quantum strut to that part. I also suggest building planes that require very little effort to stabilize. Meaning when in flight the input visualizer in the lower left hand corner of the screen should be as close to center for, pitch, roll and yaw as possible during flight. Also another good check, is a plane that will deviate very little on it's own with the SAS / RCS turned off in flight. I suggest enabling as few control surfaces and gimbaled engines on the Receiver craft as possible. This will aid in fine control while approaching the Tanker.

 

The steps to reproduce this on your own are:

 

(1) Load the Receiver and move it off the runway - I suggest Vessel Mover for this task.

(2) Return to the Space Center / SPH and load the Tanker.

(2-A) (Drogue Method) - Before take off, with both planes landed. Use a Kerbal to "Unplug" and then reattach a KAS Winch Line to the Drogue. In "Undocked" mode - If you're using lights on the Drogue, press (Alt+F12) to bring up the cheats menu and enable infinite electricity.

(3) With both planes now loaded, take off with the Tanker - Use the " [ " and " ] " keys to switch between planes. I suggest using MechJeb "Spaceplane Guidance" to hold a set altitude and heading - Don't fly too fast or you can outrun the Receiver.

(4) Switch back to the Receiver and launch it as well - Also use MechJeb spaceplane guidance but set the receiver altitude 10m lower than the Tanker. Be Careful to stay within loading distance I think that's something like 2.5 Kilometers.

(5) Match speed, and fine tune course alignment of the Receiver with the Tanker using the keyboard / joystick inputs in tandem with MJ Spaceplane Guidance - This is where the work begins.

(6) Deploy either the Probe and Drogue or the Boom at this time from the Tanker.

(6-A) (Drogue) If you use my cfg's be careful how close together multiple drogues get. The magnets are ridiculous.

(6-B) (Boom) I like to use one or two Quantum Struts to reinforce the boom back to the Tanker at this time.

(7-A) (Drogue Method) Once docking has occured, the engines on the Receiver will automatically throttle down but MechJeb will continue flying the Receiver. - Return throttle on the Receiver to just under the level used to initially catch the drogue, You want  a slight amount of tension on the KAS winch line. And allow MechJeb to stabilize the Receiver. Engines and Mechjeb's Control of the Tanker will be unchanged. As long as the drogue is attached in "undocked" mode to the winch line

(7-B) (Boom Method) Once docking has occurred, you'll need to quickly enable the Quantum Struts. Before an "Unplanned Disassembly" occurs. I like to assign the Boom to Receiver Quantum Struts "Activate" command to the "Abort" Action group. Next, control will default to the Tanker and the engines of both planes will throttle down together automatically, MechJeb will begin flying both planes together as one craft automatically. You need to decrease the engine output of the Reciever and then throttle everything back up. You want the Receiver to have a little less power than the Tanker. You can do this by disabling individual engines through action groups, or through engine right click menus as demonstrated in my video bellow (just don't shut them down completely like I did - Puts a lot of stress on the boom). Then allow MechJeb to stabilize both planes.

 

Fuel transfer is accomplished by holding (Alt) and (Right Clicking) the tanks you wish to move fuel between. Remember this only works with a "Docked" Receiver.

When you undock the two planes MechJeb will resume control automatically, of the Receiver and Tanker Independently. With whatever settings you input prior to docking.

 

When you're on final approach with either a Flying Boom or a Drogue Line. The best way to maintain good speed control is by flying too slow, and using afterburners for short boosts to accelerate toward the docking port. Then coasting on the normal engines to slow back down again. Or, set your speed too fast and then use airbrakes to slow down. Pulling the Receiver back away from the Docking Port. Either of these methods works, and it just comes down to preference. Another good method is a plane with a fair amount of drag  with quick throttle response. So as you throttle down the Receiver will slow down quickly. Larger planes are actually a little easier to dock as they are slow to make changes with control input. Slow and sloppy is good, quick and jerky is bad. Just be sure your boom is built strong enough to hold everything.

 

Videos Of Both Methods:

Spoiler

One of the first great air to air refueling videos I saw that inspired me was by "m1sz" He used air brakes, afterburners and MechJeb all in tandem to perform his Probe and Drogue docking with a regular Docking Port (much more difficult than my Custom ports)

 

 

Here is a great tutorial video by "Jagerman" He demonstrated from start to finish everything that makes for a great Flying Boom mid air dock. While using all stock parts!

 

 

My method of the Flying Boom docking, used in this video was to set my throttle slightly slower than the Tanker and leave it that way, using afterburners to close the gap. Once close to the Boom I then used short bursts from the afterburners to speed up and normal engines to naturally slow down. All the while making fine course corrections with the keyboard also in tandem with control from MechJeb Spaceplane Guidance.

 

And here is a cinematic I did, featuring the probe and drogue method

 

 

 

My Custom .cfg's And Suggested Mod Links

Spoiler

Suggested Mods

 

B9 Aerospace

B9 Aerospace - Maintenance Port

B9 Aerospace - Procedural Parts

B9 Procedural Parts - "Crzyrndm" Fork

HullCam VDS

Kerbal Attachment System

Kerbal Inventory System

RKE Kanadarm

Infernal Robotics

Infernal Robotics Rework

MechJeb

Module Manager

Procedural Parts

Quantum Struts

Tweakscale

Vessel Mover

Notepad++ - Used to edit the .cfg files

 

My custom .cfg files below are for the Squad Docking Port Jr. as well as the B9 Aerospace Shielded Docking Port. These cfg's will creat a new part with a new name. Original ports will remain untouched. They change the scale, weight, magnetic force, acquisition range, node definition - So they don't interact with any other ports. Adds Tweakscale and Hullcam VDS support, as well as a couple other small tweaks. To use them, create a new folder in your GameData folder. Name it whatever you'd like. Then copy the Squad and B9 port's folders to your newly created folder. Replace your copied .cfg files with mine listed below. And presto you have custom docking ports that will no longer interact with there original counterparts. The last cfg is a Module Manager Patch file to add Tweakscale to all the RKE Parts. For this patch file you simply need to create a cfg file with any name you'd like and place it anywhere in GameData. Be sure you have Module Manager installed. (I know there's a typo in the picture  it's been fixed in the cfg).

Custom Squad Docking Port Jr

PART
{
	name = Rfuelport
	module = Part
	author = NovaSilisko / V8Jester
	mesh = model.mu
	rescaleFactor = 0.3
	node_stack_top = 0.0, 0.1474114, 0.0, 0.0, 1.0, 0.0, 0
	node_stack_bottom = 0.0, 0.0, 0.0, 0.0, -1.0, 0.0, 0
	node_attach = 0.0, 0.0, 0.0, 0.0, -0.2, 0.0
	TechRequired = miniaturization
	entryCost = 7800
	cost = 800
	category = Utility
	subcategory = 0
	title = Refueling Mini Port
	manufacturer = Jester Aerospace
	description = Don't let the size of this docking port fool you. It may be small but the electromagnets within the port will attract the small ports together with extreme force. Careful where you put your fingers.
	attachRules = 1,1,1,1,0
	mass = 0.05
	dragModelType = default
	maximum_drag = 0.25
	minimum_drag = 0.25
	angularDrag = 0.5
	crashTolerance = 10
	maxTemp = 2000 // = 3400
	bulkheadProfiles = size0, srf
	
	MODULE
	{
		name = ModuleDockingNode
		referenceAttachNode = top
		undockEjectionForce = 0.001
		acquireRange = 20.0
		acquireTorque = 15.0
		acquireForce = 15.0
		captureRange = 0.9
		minDistanceToReEngage = 5.5
		nodeType = fuel
	}
	
MODULE
{
 name = TweakScale
 type = stack
 scaleFactors = 2.5, 3.75, 5.0
 scaleNames = Small, Medium, Large
}
	
MODULE
{
    name = MuMechModuleHullCameraZoom
    cameraName = SciCam
    cameraForward = 0, 1, 0
    cameraUp = 0, 0, -1
    cameraPosition = 0.0, 0.0, 0.0
    cameraFoVMax = 60
    cameraFoVMin = 20
}

MODULE
{
	name = HullCamera	
    cameraName = SciCam
    cameraForward = 0, 1, 0
    cameraUp = 0, 0, 0
    cameraPosition = 0.0, -0.3, 0.0
    cameraFoVMax = 60
    cameraFoVMin = 20
	
	//This camera uses film resource to get science
	usesfilm = false
	
	specialExperimentName = photo-

	specialExperimentTitle = #Anon# Picture
	
	//you still have to set this to something or it throws an error when the part loads
	experimentID = hullcampicture
	
	experimentActionName = Snap Picture
	resetActionName = Delete Picture
	collectActionName = Take Photo
	
	useStaging = False
	useActionGroups = True
	hideUIwhenUnavailable = True
	xmitDataScalar = 0.8
	
	dataIsCollectable = True
	interactionRange = 1.2
	
	rerunnable = True	
}
RESOURCE
{
	name = Resolution
	amount = 1
	maxAmount = 15
}

}

 

Custom B9 Shielded Docking Port

PART
{
    name = Rfuelportshld
    module = Part
    author = bac9 / V8Jester

    mesh = model.mu
    scale = 1
    rescaleFactor = 0.165

	node_attach = 0.0, 0.0, 0.0, 0.0, -0.2, 0.0

    TechRequired = miniaturization
    entryCost = 10500
    cost = 800
    category = Utility
    subcategory = 0
    title = Refueling Mini Port Shielded
	manufacturer = Jester Aerospace
    description = Don't let the size of this docking port fool you. It may be small but the electromagnets within the port will attract the small ports together with extreme force. Careful where you put your fingers. This version has an aerodynamic cover.
    attachRules = 1,1,1,1,0

    mass = 0.2
    dragModelType = default
    maximum_drag = 0.2
    minimum_drag = 0.2
    angularDrag = 0.5
    crashTolerance = 10
    breakingForce = 200
    breakingTorque = 200
    maxTemp = 2000 // = 3400
	bulkheadProfiles = mk2, size2, srf
	

    EFFECTS
    {
        doorMotor
        {
            AUDIO
            {
                channel = Ship
                clip = B9_Aerospace/Sounds/sound_gearRetract
                volume = 0.0 0.0
                volume = 1.0 1.0
                pitch = 0.0 0.0
                pitch = 1.0 1.0
                loop = false
            }
        }
    }
	
	MODULE
{
 name = TweakScale
 type = stack
 scaleFactors = 2.5, 3.75, 5.0
 scaleNames = Small, Medium, Large
}

	MODULE
	{
		name = ModuleDockingNode
		deployAnimationController = 1
		referenceAttachNode = top
		undockEjectionForce = 0.001
		acquireRange = 20.0
		acquireTorque = 15.0
		acquireForce = 15.0
		captureRange = 0.9
		minDistanceToReEngage = 5.5
		nodeType = fuel
	}

    MODULE
    {
        name = FSanimateGeneric
        animationName = dockingport_cdp_toggle
        startEventGUIName = Open docking port shield
        endEventGUIName = Close docking port shield
        toggleActionName = Toggle docking port shield
        availableInEVA = True
        EVArange = 10

        startRetractEffect = doorMotor
        startDeployEffect = doorMotor
    }
}

 

RKE Kanadarm Tweakscale M.M. Patch

 //RKE Kanadarm Tweakscale Patch by V8Jester


   @PART[rkekarm075]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }



   @PART[rkekarm100]
   {
       %MODULE[TweakScale]
       {
           type = free
      }
   }



   @PART[rkekarm200]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }


  @PART[rkekarm400]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }


  @PART[rkekarm600]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }


  @PART[rkekelbow]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }


  @PART[rkeklee]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }



  @PART[rkeklee]
   {
       @mass = .05
   } 


  @PART[rkekpdgf]
   {
       %MODULE[TweakScale]
      {
           type = free
       }
   }



  @PART[rkekpdgf]
   {
       @mass = .05
   } 


  @PART[rkekrotor]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }


  @PART[rkekrotor2]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   }



  @PART[rkekspacer]
   {
       %MODULE[TweakScale]
       {
           type = free
       }
   } 

 

 

 

AC-130 Spectre, Refueling from a KC-135 Stratotanker

 

Edited July 20, 2016 by V8jester

[V8jester]

29 minutes ago, Mods_o_joy said:

How did you get the awesome Refueling boom With the Canards and stuff?

If you expand the spoiler tab under "Flying Boom" There are close ups of everything so you can reproduce them on your own. Basically RKE Kanadarm, Quantum Struts, B9 P-wings and IR.

[Thingymajigy]

I'd just like to show off here

Fully stock, think this was in 1.0.2, the refueling boom can retract etc.

Once the fighter connected though, it just kept oscillating up and down till it exploded

Edited January 20, 2016 by Thingymajigy

[V8jester]

1 hour ago, Thingymajigy said:

I'd just like to show off here

...

Fully stock, think this was in 1.0.2, the refueling boom can retract etc.

Once the fighter connected though, it just kept oscillating up and down till it exploded

Oh man that's epic! I'm still so impressed as to how guys can pull some of this stuff off bone stock like that! Thanks for show'n off  

[Avalon304]

Could you share that Spectre and the Refueling planes craft files?

Edited February 4, 2016 by Avalon304

[V8jester]

On February 3, 2016 at 9:37 PM, Avalon304 said:

Could you share that Spectre and the Refueling planes craft files?

I answered this one in my other thread. But for the sake of other readers. Here is what I said there.

 

It's not just a list of mods you'd need. I also have compiled a ton of custom patches and tweaks to existing / outdated mods ever since .25 which you'd also need for some of those planes. Which further complicates me sharing my creations. They are too custom and too specific to my game. That's why I no longer provide downloads. But I am looking for suggestions for tutorial videos. Once I get a new headset, that's my next step.

[Kerbin vonKerbal]

The KC-135 is way better than the KC-10, but that's just my internal bias as a mechanic on the 135. 

[V8jester]

3 hours ago, Kerbin vonKerbal said:

The KC-135 is way better than the KC-10, but that's just my internal bias as a mechanic on the 135. 

Really!? What are some of the difference in the real world besides the onvious. More engine redundancy, shorter take off and what not. Always cool to get real world info.

[Kerbin vonKerbal]

2 hours ago, V8jester said:

Really!? What are some of the difference in the real world besides the onvious. More engine redundancy, shorter take off and what not. Always cool to get real world info.

Real world? Number of engines, amount of total fuel they hold, hydraulic fluid used in the hydraulic systems, etc. They tend to refuel Air Force One a lot. I personally like the 135 a lot though. It's basically a flying museum that still performs the mission. It's pretty straightforward, there's nothing too complex with the operation systems, and it's like 60 years old.

[V8jester]

32 minutes ago, Kerbin vonKerbal said:

Real world? Number of engines, amount of total fuel they hold, hydraulic fluid used in the hydraulic systems, etc. They tend to refuel Air Force One a lot. I personally like the 135 a lot though. It's basically a flying museum that still performs the mission. It's pretty straightforward, there's nothing too complex with the operation systems, and it's like 60 years old.

Oh, I hope that didn't come accross wrong. When I said "real wold" I just meant besides what we can observe in the game, Like more engines, possibly more stability due to those extra engines. By real world I meant things like you mentioned the hydraulic fluid, operation systems and what not. Well very cool! Now I can say I hand an actual tanker crew member on my thread

[Kerbin vonKerbal]

Haha no, I hope when I said "real world?" it didn't come across wrong! They're two different jets with the same mission. The boom on the 10 is a lot more fancy and high tech, and the boom on the soon-to-be KC-46 is even fancier. It's going to resemble what the Japanese Air Force currently has, equipped with a helmet the boom operator puts on that syncs with 3 cameras on the aft end of the jet. It's pretty cool, I had the chance to tour their plane in Alaska a while ago. 

 

But yeah, props to your refueling build. 

Edited April 8, 2016 by Kerbin vonKerbal

[V8jester]

1 hour ago, Kerbin vonKerbal said:

....and the boom on the soon-to-be KC-46 is even fancier. It's going to resemble what the Japanese Air Force currently has, equipped with a helmet the boom operator puts on that syncs with 3 cameras on the aft end of the jet. It's pretty cool ....

Really! That sounds pretty flippen cool! I'll have to look that one up. I've never heard of the KC-46 before.

[Kerbin vonKerbal]

9 minutes ago, V8jester said:

Really! That sounds pretty flippen cool! I'll have to look that one up. I've never heard of the KC-46 before.

Yeah! It's to update the fleet. The average age of the tanker is roughly 55 years old. Late 50's early 60's. I think the oldest I've worked on was a 57 or 58 year.

[infinax]

i love this but probe and drogue doesn't work well i had a fighter modification using kas docking ports it didn't go well the port kept flipping out

edit yes i just realized kas doesn't add docking ports. but for fighters the clampatron jr is to big. I need smaller docking ports.

Edited November 29, 2016 by infinax

[V8jester]

1 hour ago, infinax said:

i love this but probe and drogue doesn't work well i had a fighter modification using kas docking ports it didn't go well the port kept flipping out

edit yes i just realized kas doesn't add docking ports. but for fighters the clampatron jr is to big. I need smaller docking ports.

The OP has a MM cfg file under My Custom .cfg's And Suggested Mod Links. If you use that cfg it will add another smaller version of the clamp O tron Jr with increase range and force, to make docking much easier. You also must remember to attach the drogue to the winch on the tanker in "undocked" mode or else it will make you crash both planes for sure upon docking.

Edited November 30, 2016 by V8jester

[infinax]

1 hour ago, V8jester said:

The OP has a MM cfg file under My Custom .cfg's And Suggested Mod Links. If you use that cfg it will add another smaller version of the clamp O tron Jr with increase range and force, to make docking much easier. You also must remember to attach the drogue to the winch on the tanker in "undocked" mode or else it will make you crash both planes for sure upon docking.

 

thanks that will help