mk2 fuel tank quanity

[Ketatrypt]

Recently when I was building my space plane I noticed that the mk2 fuel tanks contained the same amount as the mk1 tanks. What do you's think of that? personally, I thought it was weird as the mk2 version is much bigger (literally twice the volume),  but maybe the advantage of body lift is good enough to offset the disadvantage of sub-optimal fuel quantity?

Edited February 10, 2016 by Ketatrypt

[Nich]

wow never noticed that.  Ya your basically paying .04t for .35 wing area which is .005t more then added wings to the MK1 and tweak scaled wings.  To save 3 parts and a mod I would say it is worth it.

Edited February 10, 2016 by Nich

[Red Iron Crown]

If you look at the endcaps of a Mk2 fuel tank you'll see that it's actually a 1.25m cylindrical tank wrapped in a lifting body wrapper. The extra mass is offset by the lifting properties as well as higher heat and impact tolerance.

[Racescort666]

This probably isn't the place to discuss this but there needs to be more variety LF only fuel tanks. After the NERVs got changed to LF only, I realized the same thing about the Mk2 parts. RIC's explanation is the same thing that I justified to myself.

[Nich]

Nervs are awesome even with an orange tank with a 3.6:1 ratio is still pretty impressive with a nerv attached to it.  an MK3 with a 7:1 is even better but not quite as good as the mk1.  I consider it a design challenge.  A single nerv with 5 mk1s has a max dv of 9.5 km/s over 21 minutes that is not as good as a 6 part ion with 22.3 km/s over 3 hours but the TWR makes up the difference

[Starhawk]

1 hour ago, Racescort666 said:

This probably isn't the place to discuss this but there needs to be more variety LF only fuel tanks. After the NERVs got changed to LF only, I realized the same thing about the Mk2 parts. RIC's explanation is the same thing that I justified to myself.

Well, SQUAD did just hire taniwha, the author of Modular Fuel Tanks.

Happy landings!

Edited February 10, 2016 by Starhawk

[Edax]

One way to increase fuel capacity is to use a MK2 bicoupler, then attach MK1 fuel tanks at the attach points, then close the other end with another MK2 bicoupler.  You'll be able to carry twice the amount of fuel for the equivalent MK2 length.

[moogoob]

As others have said, I use them for their aerodynamic properties in the Nastybird, where they serve their purpose well as internal orbital maneuvering (IE post-launch) fuel tank. I think if they held more fuel they might weigh too much.

[Snark]

7 hours ago, Starhawk said:

Well, SQUAD did just hire taniwha, the author of Modular Fuel Tanks.

Yes, but I wouldn't read too much into that.  For example, they hired Porkjet ages ago, and he's the author of Stock Fuel Switch. 

Supposedly, rockets will finally get some love around 1.2, after the past half-dozen patches or so that have been coddling spaceplanes-and-nothing-but-spaceplanes... so maybe we'll get something then?  Lack of rocket-friendly LF tanks has been a glaring hole ever since 1.0, we really need some decent tanks to play with.

2 hours ago, Edax said:

One way to increase fuel capacity is to use a MK2 bicoupler, then attach MK1 fuel tanks at the attach points, then close the other end with another MK2 bicoupler.  You'll be able to carry twice the amount of fuel for the equivalent MK2 length.

Careful about that-- it doesn't work the way you think.  Sure, it'll look kinda cool.  Because of the tree structure of KSP craft, however, it won't really be connected.  Both of the tanks will be attached on one side, but only one of them will be attached on the other side, meaning you'll have a structure that's much less strong and rigid than you expect (and, even worse, will be asymmetrically strong).

My own solution to the "lack of good LF tanks" problem is to just hack up my own modded versions of the 4-ton, 16-ton, and 32-ton LFO tanks that are LF-only (and have a tweaked texture so that I can visually distinguish them from their LFO variants), and that manages to keep me from going into a rage and running amok, at least until Squad has time to fill this gap.

[Starhawk]

28 minutes ago, Snark said:

Yes, but I wouldn't read too much into that.  For example, they hired Porkjet ages ago, and he's the author of Stock Fuel Switch. 

Oh, I know.  I was just stirring the pot a bit, really.

28 minutes ago, Snark said:

Supposedly, rockets will finally get some love around 1.2, after the past half-dozen patches or so that have been coddling spaceplanes-and-nothing-but-spaceplanes... so maybe we'll get something then?  Lack of rocket-friendly LF tanks has been a glaring hole ever since 1.0, we really need some decent tanks to play with.

Yes, I'm constantly compromising my designs to fit the limitations of the fuel tanks available in the stock game.  And using combinations of the various 'adapter' tanks with Mk3 LF tanks.
I'm hoping for some changes here soon, as well.

Happy landings!

[Edax]

5 hours ago, Snark said:

 

Careful about that-- it doesn't work the way you think.  Sure, it'll look kinda cool.  Because of the tree structure of KSP craft, however, it won't really be connected.  Both of the tanks will be attached on one side, but only one of them will be attached on the other side, meaning you'll have a structure that's much less strong and rigid than you expect (and, even worse, will be asymmetrically strong).

 

I used to think that (in fact, I think that may have been true last patch), but it when I was tweaking my flying wing design, it had a tendency to flop apart at around 800 m/s (the two ends of the ship were joined together by a knitting of struts.  It wasn't until I stuck the bicouplers at the end to join the two halfs of the ship together that stability dramatically improved and the spaceplane no longer ripped itself in two, and could reach orbit.

[Snark]

6 minutes ago, Edax said:

I used to think that (in fact, I think that may have been true last patch), but it when I was tweaking my flying wing design, it had a tendency to flop apart at around 800 m/s (the two ends of the ship were joined together by a knitting of struts.  It wasn't until I stuck the bicouplers at the end to join the two halfs of the ship together that stability dramatically improved and the spaceplane no longer ripped itself in two, and could reach orbit.

It's still true, even now.

It's worth noting that the spaceplane you picture doesn't have this problem, because it doesn't make any closed loops.  At no point do you have two bicouplers with their "twin" sides facing each other and something trying to connect in parallel.  You've got a connection path that has some zigzagginess to it, but no loops.  So the original comment still stands.

[Edax]

It's still true, even now.

It's worth noting that the spaceplane you picture doesn't have this problem, because it doesn't make any closed loops.  At no point do you have two bicouplers with their "twin" sides facing each other and something trying to connect in parallel.  You've got a connection path that has some zigzagginess to it, but no loops.  So the original comment still stands.

 

Maybe this image will help.  The tail section bicoupler joins both sections together.

 

Edited February 11, 2016 by Edax

[Snark]

2 minutes ago, Edax said:

Maybe this image will help.  The tail section bicoupler joins both sections together.

Okay, I see what you're doing there, but... pretty sure KSP hasn't gotten away from the tree structure.  It's the sort of thing we would have heard about.  Even right down to the file format in the way parts reference each other.  A move away from tree structure in KSP would be titanic, not something silently slipped into a minor update like 1.0.5.

So no, the tail section bicoupler does not join both sections together.

Gonna go out on a limb here and suggest a simple test:  with the plane assembled in its supposedly both-sections-joined state, get a small fuel tank (anyway, something that has top and bottom connection nodes), hold down the "alt" key to force it to "attach only on nodes", and then try waving it around in the vicinity of where that tail bicoupler connects.  If I'm right and only one of the two sides is actually connected, I'd expect the fuel tank to snap-and-connect on whichever is the unattached side (since there are a couple of unattached nodes in there, even though you can't see 'em because they're hidden facing each other).

Incidentally:  You do have both sections joined together with that "X" of fuel lines.  Could that be the thing holding your left & right sides together?

(Also, just a sanity check, you're not running KJR or something, are you?)

[Edax]

40 minutes ago, Snark said:

 

15 minutes ago, Snark said:

Okay, I see what you're doing there, but... pretty sure KSP hasn't gotten away from the tree structure.  It's the sort of thing we would have heard about.  Even right down to the file format in the way parts reference each other.  A move away from tree structure in KSP would be titanic, not something silently slipped into a minor update like 1.0.5.

So no, the tail section bicoupler does not join both sections together.

Gonna go out on a limb here and suggest a simple test:  with the plane assembled in its supposedly both-sections-joined state, get a small fuel tank (anyway, something that has top and bottom connection nodes), hold down the "alt" key to force it to "attach only on nodes", and then try waving it around in the vicinity of where that tail bicoupler connects.  If I'm right and only one of the two sides is actually connected, I'd expect the fuel tank to snap-and-connect on whichever is the unattached side (since there are a couple of unattached nodes in there, even though you can't see 'em because they're hidden facing each other).

Incidentally:  You do have both sections joined together with that "X" of fuel lines.  Could that be the thing holding your left & right sides together?

(Also, just a sanity check, you're not running KJR or something, are you?)

Even if the two points aren't technically joined (yes, I could attach a fuel tank on the right side), it still dramatically increase stability, compared to before when I had both sides hanging, with a bunch of struts holding it together (stability was so good, I removed all the central struts).

Do the fuel lines even hold thing together like struts?  

(Not running KJR)

[Snark]

Just now, Edax said:

Even if the two points aren't technically joined (yes, I could attach a fuel tank on the right side), it still dramatically increase stability, compared to before when I had both sides hanging

Having trouble picturing what you mean by "both sides hanging."

1 minute ago, Edax said:

Do the fuel lines even hold thing together like struts?

I believe so, yes.  Not sure if they're quite as rigid as struts (i.e. they may have a weaker spring constant?), but they do tie things together at least to a certain extent, yes.

[Edax]

2 minutes ago, Snark said:

Having trouble picturing what you mean by "both sides hanging."

Essentially, the plane use to split in two right at the front bicoupler so all the weight of each half of the ship is hanging from those reaction wheels, which meant each side of the ship would dangle independently depending on drag forces.

[Red Iron Crown]

Edax, your plane will be asymmetric aerodynamically. Only one of the nodes of that bicoupler will attach, occluding that node from the airflow. The other node will remain open, and be as draggy as if there was nothing in front of it (in stock aero anyway, FAR handles this case I believe).

[kurja]

Such tri/quad/bicoupler loops can be closed with docking ports.