[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[espm400]

I did movable wings ( well, wingtips ) with Damned Robotics a while back and it did work as it was meant to, to shift the CoL a little, so I suspect we just need a better hinge part. Wings attached to DR hinges are not terribly stable.

For supersonic craft especially you really want the CoL ball inside the CoM ball in the SPH, and preferably at the balance point of the tanks, although all you really need is enough tankage either side so you can pump fuel around a little to trim for various parts of a mission ( mainly referring to spaceplanes at this point ). Don't forget once you go supersonic the CoL is going to move backwards.

I like this:

-snip-

And for spaceplanes I don't think I've ever got better than this:

-snip-

The only reason I keep my CoL back a bit (especially with my HL Cargo setups B9) is that usually I'm dealing with a lot of fuel tanks, and since KSP likes to drain the front tanks first, I like to give myself a bit of leeway. Back in .19 I think, I had an SSTO for moving crew around my stations. Well one particular mission I was bringing 12 Kerbals back to the KSC from orbit in a newish, somewhat untested version of said ship and due to the front tanks being drained and the CoM shifting (and no way for me to see it outside of the SPH/VAB), I ended up in an unrecoverable spin as soon as I hit the dense atmo. Hence, I keep my CoL back a bit, just in case. Mind you, for most of my SSTO craft I tend to take quite a high exit trajectory to orbit, thereby quickly bypassing what to me has become that dreaded transition area between atmo and space.

EDIT: I did some moveable wings with Damned Robotics myself, but I could never get the aesthetic I wanted. I either had to offset the wings vertically, or do a biplane-style front wing section with a single sweepable wing, or visa-versa.

Edited June 26, 2013 by espm400

[Van Disaster]

TAC fuel balancer is an essential part of all my spaceplanes. I tend to drain the front tanks on the way up to cover transonic issues where I don't have enough front lift, then balance them all until I want to re-enter - maybe pump a bit around if I'm having issues transferring to orbit, sometimes the plane goes a bit odd when I finish my AP burn. At re-entry I usually pump one of the front tanks as full as it can go until I'm back in normal atmospheric flight, and then balance them again. Being able to pump fuel about is wonderful.

[ferram4]

@Black-Talon: Trying to set up the FARControllableSurface module to work on wings with control surfaces causes some very weird things to happen, primarily because it acts as if the entire wing part is rotating. FAR can zero out the values for Winglet and ControlSurface parts in-game, so changing that is unnecessary. Further, the FSwingletRangeAdjustment can only affect the stock ControlSurface part, not FAR parts. The extra values in the Firespitter configs are old fields and are unnecessary.

Finally, if only Cl is appearing on you AoA sweep then that means that something is wrong in the drag / moment calculations and those values are being pushed off the chart.

@Asdefjak: The "isShielded" field only applies to parts in cargo bays and payload fairings. Everything is functioning properly. I guess I'll just remove the visibility of that field to reduce confusion.

[theflyingfish]

I can never land my planes, but all of them take off at more than 100 m/s. Some even break the sound barrier before leaving the runway, like my SpaceShipOne + White Knight build.

Wait, WHAT.

[ialdabaoth]

@asdefjak: the "isshielded" field only applies to parts in cargo bays and payload fairings. Everything is functioning properly. I guess i'll just remove the visibility of that field to reduce confusion.

thank you.

[Spanier]

Is there a incompatibilty with some other mods using modulemanager? Because I have a weird bug that causes to eliminate air resistance on my rocket as it moves. While still on the launch pad it gives me a terminal velocity of 1,244 m/s (measured by MechJeb).

[ferram4]

@Spanier: It is addressed here. The error is due to MechJeb calculating things using the old drag model, which has been zeroed out.

[Spanier]

@Spanier: It is addressed here. The error is due to MechJeb calculating things using the old drag model, which has been zeroed out.

Well, ok so MechJeb does a wrong calculation, but temporarily it worked fine, so why it does no more?

[foamyesque]

Thank you ferram, that works wonderfully. I can now reenter in the 3 man pod directly from leaving the mun. Periapsis 18-21km seems to be the sweet spot (18km and using angle of attack between 35 and 25 degrees got me down in one orbit) and somewhere in that range is the apollo style double skip maneuver (I've yet to find it).

Edit: Do you know what we should do with the expandable 6.25m shield? It goes from 2.5m to 6.25m and currently has node size 2.

I tried kicking it to 2, but I still get next to no drag as compared to an unshielded pod.

[ferram4]

@Spanier: MechJeb should never "work fine" with FAR, as it is unable to determine the drag forces that FAR applies to the vehicle. If it was "working" in anyway then that means that you were using a vehicle that either:

1. Had a large number of intakes
   
2. Had a large number of parachutes
   

Both of those still apply drag through the stock drag model.

@foamyesque: Are you talking about the shield for the 3-man pod or the expandable heat shield? If it's the former, make sure that both attach Nodes have the proper values and that they are not overriden by modulemanager at any point. If it's the latter, I don't know what to tell you, I don't have the math of that set up yet.

[MR4Y]

Wait, WHAT.

I made a SpaceShipOne replica along with it's lifter aircraft, called White Knight. the SpaceShipOne was the first space plane made by a company not affiliated with the government, like NASA.

Here it is, attached to the White Knight plane, which was used by NASA to carry some payloads to higher altitudes for testing, including some of their X-Planes.

And here's is my SpaceShipOne + White Knight:

[cxg2827]

I'm having a bit of trouble with a SSTO spaceplane. I made a craft, got it into orbit, but then messed up the save file in the SPH. I've tried recreating it as close as possible, but now when I'm at 1,700m/s and transition the sabers to rocket mode, it causes the craft to flatspin.

any clue what i can do with this to fix the issue?

here is the one currently in orbit.

Edited June 28, 2013 by cxg2827

[Van Disaster]

Did you check both engines and nosecones are actually in the action group to switch mode? it doesn't save across edits using symmetry.

[cxg2827]

Did you check both engines and nosecones are actually in the action group to switch mode? it doesn't save across edits using symmetry.

both engines and intakes highlighted when I selected one for the action group. I'll take a look to make sure both are actually toggling and not one side.

[smunisto]

Highlighting, even for grouped parts in actions groups is notorious for being glitchy and not actually toggling all parts. Check it again and try.

Also...how does this thing even fly with such a difference between CoM and CoL?

[foamyesque]

@foamyesque: Are you talking about the shield for the 3-man pod or the expandable heat shield? If it's the former, make sure that both attach Nodes have the proper values and that they are not overriden by modulemanager at any point. If it's the latter, I don't know what to tell you, I don't have the math of that set up yet.

It's the 3-man one, and the nodes are sized to 2 in the VAB, as seen here:

I wonder: Is it a MM conflict or something? When I installed DRE it asked me to overwrite a previously existing MM, which I believe was the one that was bundled with FAR. I said yes. I haven't noticed any issues with the normal parts, though.

[Van Disaster]

Highlighting, even for grouped parts in actions groups is notorious for being glitchy and not actually toggling all parts. Check it again and try.

Also...how does this thing even fly with such a difference between CoM and CoL?

That's fine, it's if the CoT is off from CoM ( and CoDrag, albeit that's guesswork ) that you start getting horrible issues. I don't see what all that dihedral is doing though.

[Monkthespy]

Something occurred to me, due to simulation of fairings, would it work putting a small shuttle in a large fairing? Would the wings still work or would that fairing negate all that aerodynamic lift?

[theflyingfish]

I made a SpaceShipOne replica along with it's lifter aircraft, called White Knight. the SpaceShipOne was the first space plane made by a company not affiliated with the government, like NASA.

-shnip-

I know what the White Knight + SS1 combo is. I was referring to the fact that you said that your replica takes off at over Mach 1. And looking at the smoke trails and condensation effects in your second picture, it does indeed look like it's moving along at a substantial clip.

How did you get a captive-carry cargo aircraft to Mach 1 in the first place, much less take off with it?

[cxg2827]

Also...how does this thing even fly with such a difference between CoM and CoL?

Its a bit nose heavy, so full deflection of the surfaces for pitching is very slow reacting, and only causes it to have a "minor stall detected" under Mach 1.0 when at full control throws. I kind of like it this way since maneuverability isnt an objective with this plane. But, there is definite room for improvement.

That's fine, it's if the CoT is off from CoM ( and CoDrag, albeit that's guesswork ) that you start getting horrible issues. I don't see what all that dihedral is doing though.

Ive added the dihedral to help stabilize the rolling a bit. much more stable at higher mach numbers, but I still get a bit of dutch rolling when I'm pointing about 5 degrees above the prograde marker. letting go of the stick allows it to get back to the prograde direction and stops the wagging.

Might need to tone it down though.

[s20dan]

This aircraft can't seem to carry any cargo in it's hold due to added drag from the cargo.(Everything is unshielded):

Anyone know how to fix that?

Cheers.

[ferram4]

@foamyesque: Make sure you're using the latest ModuleManager, although I doubt that would affect the drag of that part. I woul;d suggest actually updating to 0.9.5.1 since the difference in aerodynamics between the version you're using and the latest version could be causing the issue.

@Monkthespy: The payload fairing will cancel out all of the aerodynamic forces on the shuttle. It wouldn't be a useful payload fairing if it didn't.

@s20dan: There is a known issue with parts at the very edges of cargo bays not being shielded properly, although I think that any parts placed more in the middle of the bay will still be shielded properly.

[s20dan]

@ferram4: I've seen that bug, but this is a little different. Anyway it seems its solved by opening and then closing all cargo bays, then the cargo is correctly shielded.

[foamyesque]

@foamyesque: Make sure you're using the latest ModuleManager, although I doubt that would affect the drag of that part. I woul;d suggest actually updating to 0.9.5.1 since the difference in aerodynamics between the version you're using and the latest version could be causing the issue.

Updated and with size 2 nodes on the heatshield, Cd is roughly 0.04; that's 4x higher than before, but still 1/10th the bare backside of the pod. =/

[Punk]

I am having issues with fairings. With them I can only control an angle of attack of less than 2 degrees but without them it is far more lenient. I am using an ssto lifter that looks a lot like a russian Soyuz with four outer columns with 2 LV-T30 and an LV-T45 under each around a center tank stack that narrows down at the bottom (I would post an image but can't work out how using this site). The fairing makes up the top 1/3 of the craft. It has a TWR at launch of 1.75 with smaller payloads. With the fairings I struggle to control attitude and end up flipping out of control soon after beginning a grav turn (3-4000m). The CoL indicator is above the CoM and pointing perpendicular to the central axis of the rocket, as though the fairings act like a vertical wing. Should I try using all LV-T45's for more authority or do FairingFactory fairings just not work with FAR yet? I will try to upload an image in a bit. Cheers.