ferram4

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

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hopefully @ferram4 can weigh in here but if anyone else has thoughts - how realistic would it be to use the AoA tweakable as a trim control? The problem I have always had with the way the game handles trim is that it moves the entire control surface, which is not how trim works IRL. Doing this, you limit the movement of the control surface which can more easily lead to dangerous situations like coming in for a landing and not being able to pitch the nose up enough because the trim is set to high and your control authority is limited. Using the AoA tweakable in flight gives the effect of trim but retains full motion of the control surface.

As for the accessibility issue of adjusting the control, I'd do it with kOS script triggers bound to my joystick hat buttons so actually using it would be easy. Just wondering if there's any consequences about doing this I'm not thinking about.

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On 4/10/2018 at 2:38 AM, Drew Kerman said:

The problem I have always had with the way the game handles trim is that it moves the entire control surface, which is not how trim works IRL. Doing this, you limit the movement of the control surface which can more easily lead to dangerous situations like coming in for a landing and not being able to pitch the nose up enough because the trim is set to high and your control authority is limited. Using the AoA tweakable in flight gives the effect of trim but retains full motion of the control surface.

You seem to be confused with how trim works on real aircraft. The simplest mechanism for adjusting trim are trim tabs (small control surfaces) mounted to the larger primary control surfaces. These tabs do set trim by changing the ''default' neutral position of the primary control surface. The trim tabs essentially "fly" the primary control surface at a new neutral position which in-turn adjusts the relative aerodynamic forces produced by the airfoil it is mounted to. This technically DOES reduce overall control surface travel in a given direction dependent on the amount and of trim imposed. But trim adjustments are typically so minor relative to the large amount of control deflection this is never an issue. A control surface has a finite amount of design deflection within which control authority can be achieve, including the trimming of the aircraft.

The less common method for trimming an aircraft which is used on heavier aircraft with hydraulic and/or computer actuated control surfaces is to forgo the trim tabs and simply fly the control surface via hydraulic actuation at whatever amount of defection within it's limits in order to trim the aircraft for the desired flight characteristics. The effect at the control surface is the same as if the pilot were applying the desired amount of pressure on the controls constantly, but obviously this is not the case, it is just a matter of adjusting default position for the hydraulic actuators. But practically to the pilot the effect is the same as the trim tab method.

In either case, the absolute position of the primary control surfaces within their range of motion is changing to adjust trim. Thus affecting the amount of additional degrees that control surface is capable of deflecting from it's neutral (for that trim setting) before hitting it's design limits.

Edited by li7in6

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On 4/4/2018 at 3:19 PM, ss8913 said:

fair enough; however the official release of the current version does not work with *any* parts :)  I can post the modified .dll if that's ok with ferram4, or I can just sit on it.

 

If you want to build it yourself with visual studio community 2017, open the solution file in visual studio, edit CompatibilityChecker.cs and change the minor version from 3 to 4, or add an "or" clause... make sure to add the appropriate 64-bit KSP references to *both projects*, set the build type to release, push F6, builds.  copy the resulting .dll files into your appropriate KSP GameData/ locations.  Obviously this explanation requires a bit of knowledge about VS, albeit not that much.

Can you explain better? I'm trying to get this to work, but I need to know where to actually find the files you're talking about to edit them. I kinda get stuck when you say open the solution file and I don't even know where that is.

 

Edit: Nevermind, I'm just stupid today. I was looking in the already compiled mod instead of in the source code.

Edited by teren989

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Shoutout to @ferram4

I haven't been it a ksp mood for a few months and really just check the forum to see how things are going, but it's nice to see that this mod is still going strong, I can't imagine how frustrating it must be to get it updated to work with the current version of ksp and then boom next one gets released. (and then THAT question pops up)

Not a pry at trying to get it to 1.4 or anything like that,(as i said i haven't jumped back into playing yet) just a thx for the truly MASSIVE amount of work you throw into this. there are tons of great mods for ksp but not many have the complexity that this must have. 

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On 4/10/2018 at 11:38 AM, Drew Kerman said:

hopefully @ferram4 can weigh in here but if anyone else has thoughts - how realistic would it be to use the AoA tweakable as a trim control? The problem I have always had with the way the game handles trim is that it moves the entire control surface, which is not how trim works IRL. Doing this, you limit the movement of the control surface which can more easily lead to dangerous situations like coming in for a landing and not being able to pitch the nose up enough because the trim is set to high and your control authority is limited. Using the AoA tweakable in flight gives the effect of trim but retains full motion of the control surface.

As for the accessibility issue of adjusting the control, I'd do it with kOS script triggers bound to my joystick hat buttons so actually using it would be easy. Just wondering if there's any consequences about doing this I'm not thinking about.

@Drew Kerman Basically what @li7in6 said, the trim in most real aircraft works exactly the same as in game: the neutral position is shifted, but it doesn't change the range of the control surface. In airliners, the entire stabilizer assembly changes its angle of incidence to trim, which allows the elevator range to be retained.

I suppose that's what you mean by "AoA tweakable", but to get this out of the way, because I''m not sure if you understand what AoA is based on your post: Angle of Attack is not a property of the wing, it's not included in FAR configs at all and it can't bee controlled by FAR. AoA is the physical angle between the airflow velocity vector in far field and the longest chord of the lifting surface. You can't change the AoA of a part with a tweakable slider, the AoA depends on your aircraft's pitch and in order to change it without changing pitch you have to physically rotate the wing part along its span relative to the rest of the aircraft(in which case it's better to refer to it as Angle of Incidence not Angle of Attack).

So to do what you're trying to do (i.e., if I understand correctly, an airliner style all-moving elevator trim) you have to use Infernal Robotics. The way I do it when I make airliners in KSP is to simply attach the horizontal stabilizers to the tail through  rotatrons and then offset the rotatrons inside the fuselage so they don't stick out, and offset the stabilizers away from them to align them with the fuselage. Finally I invert one of the rotatrons (otherwise they're going to rotate in opposite directions when you trim), set the range to something reasonable for an airliner (e.g. for 737 it's 17 degrees from full nose down to full nose up), put them both in a single group and assign the group to keys I want to use for trim (the RCS translation keys are good for this purpose, since you're not going to use them anyway in an airliner). It's also a good idea to limit the speed to something realistic, like 0.2-0.3 deg/s. You can also use kOS to automatically trim when you deflect the stick beyond a certain value without any keystrokes, as kOS features direct support for IR - tested and it works marvellously.

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It may be annoying when people repeatedly ask modders for updates, but that's no reason to be rude to forum newbies. A post or two have been removed from this thread. 

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There is no argument which is going to convince us to allow people to be rude to other forum members. More posts removed. Leave it alone. 

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On 4/12/2018 at 7:10 PM, li7in6 said:

You seem to be confused with how trim works on real aircraft.

There's also the general principle in airframes that small control surfaces and small trim tabs, as opposed to whole moving fins for control and trim adjustment, work better at slower speeds.  The small moving surfaces change the aerodynamics of the fin to provide control or trim.  At higher speeds, the greater effects of whole moving surfaces is needed and performs better.

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8 minutes ago, Jacke said:

There's also the general principle in airframes that small control surfaces and small trim tabs, as opposed to whole moving fins for control and trim adjustment, work better at slower speeds.  The small moving surfaces change the aerodynamics of the fin to provide control or trim.  At higher speeds, the greater effects of whole moving surfaces is needed and performs better.

isn't that what he said?

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Strange question for @ferram4; is there any way for you to use FAR but use the stock winglet/canard menu rather than the version FAR uses?

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Was there any major change in the way the vanilla game calculates aerodynamics? 

I'm just wondering if there's a lot of work for ferram compared to other updates, and also wondering how well the current version works with 1.4.2.

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Can someone explain how the AOA%, BrakerRudder%, Ctrl Dflct and Mass strength multiplier % values affect the working of a control surface? I browsed the wiki, but couldn't find any mention of those settings.

What I can guess from the names is that Ctrl Dflct decides how much up, down, left or right a control surface can move, regardless of what you're using it for. The pitch, yaw and roll are also mostly self explanatory, it's how much the surface will respond to the respective controls. The thing is there is no direct "Angle of Attack" control in KSP as far as I'm aware. So I can't figure out how that value is affecting gameplay. Same goes for BrakeRudder and Mass strength multiplier.

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1 hour ago, scimas said:

Can someone explain how the AOA%, BrakerRudder%, Ctrl Dflct and Mass strength multiplier % values affect the working of a control surface? I browsed the wiki, but couldn't find any mention of those settings.

What I can guess from the names is that Ctrl Dflct decides how much up, down, left or right a control surface can move, regardless of what you're using it for. The pitch, yaw and roll are also mostly self explanatory, it's how much the surface will respond to the respective controls. The thing is there is no direct "Angle of Attack" control in KSP as far as I'm aware. So I can't figure out how that value is affecting gameplay. Same goes for BrakeRudder and Mass strength multiplier.

%AoA let your control surface deflect according to the angle of attack.

100% means that when your global AoA is 10 degree,the control surface will deflect until reach a local AoA of 20 degree where -100% means that the control surface will always deflect toward the velocity vector.

Brake rudder makes the elevon or flaperon act like a rudder by producing drag for yaw control for flying wings such as B2 Spirit that vertical tail is absent.

Mass strength multiplier means the structural strength of a wing surface. The higher the value, the heavier the wing but the lift force that can be withstand by the wing without breaking it also increases.

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21 minutes ago, Ryds said:

Is this mod dead now?

No.

Quote

ferram4 released this 18 days ago

Shock and horror, no new FAR release in 18 days, what will we do? :rolleyes:

Edited by steve_v

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13 minutes ago, LjSpike said:

FAR isn't showing up as compatible on CKAN?

It  wont for any KSP version above 1.4.x until the next update.

However...

If you are running KSP 1.3.3, it should be there if I am not mistaken. 

Edit I: And if it is still not there for 1.3.3, then just install the latest version manually. 

Edited by ISE

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3 hours ago, ISE said:

It  wont for any KSP version above 1.4.x until the next update.

Ah ok. Not sure which version I'm running but that's probably it.

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The latest version has the following in the Changelog :

Quote

"Added ability to override structural stress values for aerodynamic failures on a per-part basis"

Would this make it possible to exclude select parts from aerodynamic failure and if so how?

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Ferram seems to completely break on reentry (at least) in the DLC missions. Ie, a pod will come down as usual and still have orbital velocity when it impacts, or just burn up even at a shallow angle. The flight data display shows garbage and there will be absolutely no drag (but plenty of heating.)

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On 4/19/2018 at 7:40 PM, ZooNamedGames said:

Strange question for @ferram4; is there any way for you to use FAR but use the stock winglet/canard menu rather than the version FAR uses?

I'm wondering this as well, as the only bug I'm having with 1.4 is that the control surface settings window buttons don't work, and I guess this also zeroes the deflection allocations because I have no response from any control surfaces, stock or modded. This is obviously problematic for an aircraft. If I can change one config file and just use the stock buttons for setting pitch, yaw and roll control that'd be great.

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I think Ferram initializes something on the first visit to space center. Scenario missions almost always bypass space center completely, try visiting space center before reentry, it might just work. =0 

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