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

[Torminator]

FAR changes a lot about how rockets work. Specifically, your rocket has to be aerodynamically stable as well as big and shouty. It's typically easier to get loads into orbit because there's less air resistance, but also more difficult because it's much easier for a rocket to lose control on ascent.

Control surfaces work just fine out of the box. You only need to adjust them to eliminate the silly things Vanilla does, like your Rudder trying to be an aileron.

[Sparker]

@Sparker: It is possible, however you need to understand that the space shuttle and buran were designed to reenter at ~35-40 degrees angle of attack, which means that they made a lot more drag than lift. It's likely that your spaceplane made much more lift than drag and so was able to lift out of the atmosphere..

Thanks. I remember I heard somewhere a long time ago that shuttle could enter the atmosphere at a shallow angle, leave some kind of a bomb there and get back into orbit by bouncing from atmosphere.

Are you planning to add support for this cargo bay? When I put something inside it and right-click on the payload it says 'Is shielded:false' and it seems to produces some drag, even if closed.

Edited August 23, 2013 by Sparker

[Ratzap]

Sorry for the wall of text. Anyway, don't get me wrong, I love this mod and appreciate the work you're doing. I'll just stick to B9 wings rather than procedural for the time being.

Great breakdown and analysis. I came to the same conclusion yesterday with much less science while trying to build a stable plane around the kethane engine. Pwings are fun and easy to use but I just couldn't get the plane to stay in the sky. B9 wings did the job.

[Van Disaster]

@ferram: that paragraph told me volumes about ksp-specific aircraft design - If FAR really does need 5 pages of info at that density for ksp specifics then serious kudos to you, especially for keeping working on this. I don't think the guide needs to go into the details of shock induced flow separation, though. Maybe if we get to using detailed aerofoil cross-sections or something. A few notes on things like "how to reduce inertial coupling" or maybe a "here's this plane, let's see what's wrong with it with the CAS and fix it" walkthough might be a nice thing.

pWings can be a bit odd: I've got at least one design that turns the static analysis into a horrorshow, yet it's perfectly stable & docile in flight ( and that's with any cockpit torque disabled ), and another that looks ok but wants to roll left constantly. Have you tried using multi-segment pWings?

Pyromaniacal: I use NovaPunch atm for the 3m parts, KW with the 0.21 update someone did should be just as good if you want big rockets. The problem is that rockets need to be proportionally long and thin to be less draggy, but KSP doesn't really like long thin structures - and the shorter and fatter the rocket the less stable it is under FAR. I generally use three crossfeeding stacks ( Falcon Heavy style ) as a compromise, which is working fine. 3x3.5m stacks can lift an awful lot.

[NathanKell]

Has anybody made a Delta V chart with FAR in mind? Or just know the general amount of Delta V you save getting into orbit with this mod?

My best on 0.20 was 3100m/s. .21 seems to require a little bit more. Then again, my 0.625m rockets with cheapo SRB first stages require something like 3500.

I have a set of launchers that have been proven to get certain masses up to certain orbits. These lifters use asparagus staging. All have nosecones. Does FAR make this less effective? Will they still lift like they did? Should I instead pick up a pack like NovaPunch or KW Rocketry? Which do you all prefer?

I've never really had problems with asparagus designs in FAR (not that I use them regularly, but I have used them at times). Make sure you have sufficient fins at the bottom of each stack (so your COL will remain below COM) and you'll probably be fine. It'll take more delatV than an optimized rocket, but it'll still take way less deltaV than it used to.

Example: Temstar's Zenith series (6-booster asparagus) will put 1.5x the rated payload in orbit, with no issues at all.

[Ratzap]

FAR works with novapunch no problems and I use asparagus designs a lot - all working no hassle with FAR. Even my launchpad base on Duna seems to benefit from FAR - ~2300 from surface to SoI escape. Using proc fairings of course.

[Pyromaniacal]

Temstar's Zenith series (6-booster asparagus) will put 1.5x the rated payload in orbit, with no issues at all.

Yeah, those are the lifters I use too.

[ferram4]

@PetWolverine: I'll have to look into the way the moments and products of inertia are handled. It may be a problem on my end, otherwise it's probably a procedural wings bug.

@Subcidal: The delta-V necessary to launch from a body with an atmosphere is very, very dependent on the vehicle's aerodynamics. I've seen drag losses below 100 m/s and drag losses up to 500 m/s, depending on the aerodynamics of the rocket.

@Pyromanical: Control surfaces need to be assigned to specific axes if you want them to function in a useful manner, otherwise they'll respond to control inputs the way they do in stock KSP, but with the proper aerodynamics.

Depending on how your rockets are designed, they may launch more to orbit than they did in stock KSP. While asparagus staging (as well as all parallel staging) is not as aerodynamically efficient as series staging with FAR, it is still more aerodynamically efficient than it was in stock KSP. Just remember that if your rocket is incredibly wide compared to its height it might end up being unstable, which would end very bad for anyone or anything on board it.

@Sparker: Try going into the part.cfg for that part and change the title from "Spacejunk Bay" to "Spacejunk Cargo Bay". That should allow FAR to identify it properly.

[DresCroffgrin]

For ferram or anyone else who may know:

Using FAR 9.5.6, I am experiencing a "ghost force" that creates significant roll and a small amount of yaw that starts between Mach 3 and 3.75. It only appears on some planes, and it seems to be more significant on planes with a CoL above and behind the CoM (less pronounced when CoL is behind but not above CoM). Are there any known bugs or common construction mistakes that can cause this? I can post pics of afflicted planes if that would help. Thanks!

[Torminator]

Certain layouts/conditions can cause one surface to stall, and one not, leading to a loss of control. (This is what makes flat spins so ridiculous; one wing has lift, the other doesn't, and it creates a spin that just intensifies that.)

A picture of a craft it happens to would probably help the smart people help you

[icecubecookie]

ermmm.... so im having this problem with the B9 aerospace intakes after version 9.6

somehow my drag jumped by around 8-9 times with the intakes on than without

version 9.5.51 had lower drag, my aircraft could cruise at 300++m/s at 1km altitude, but now my max speed is around 155m/s

so im wondering if the problem is the same as the blade taper for propellers

Edited August 24, 2013 by icecubecookie

[Pyromaniacal]

Well, I downloaded and installed the plugin, and I have to say, this is amazing. I took a shuttle that couldn't make it off the runway, and put it in a 85km suborbital trajectory. A few modifications, and I'll have my crew change SSTO that I've been trying to make! Definitely worth downloading!!

For the rockets, though, if asparagus staging is less efficient, then should I get a parts pack that has fuel tanks/engines that have a wider radius, like KW or NovaPunch? Which would people recommend? Will anyone notice that I asked this already?..

The answer to that last one is probably yes...

One final thought, are there hotkeys for the wing leveler, pitch limiter, and yaw limiter? I fly with a joystick, and it was annoying switching from the stick to the mouse to disable the assists while landing.

[shabbycow]

When i install this mod both the stock jet engines only produce 140 thrust. I've tried installing just FAR and no other mods on a fresh install of the latest version of KSP, still won't disappear...Happens with both 0.9.5.5 and 0.9.6. Anyone else have the same problem? I have no idea how to fix it, i looked at the cfg for the parts, and they both show 225 and 150 like they should.

[Van Disaster]

RE: B9 intakes - it's only the large intakes, the little DSI intake hardly registers.

Closing the intake makes drag worse(!)

Edited August 24, 2013 by Van Disaster

[ferram4]

@DresCoffgrin: If it's only on certain planes make sure that your vertical tail is on perfectly straight. On some designs the editor can actually leave the tail angled to one side or the other which can cause rolling and yawing tendencies. Other than that, it might just be the plane becoming unstable at higher speeds; try adding a larger vertical tail to see if that helps.

@icecubecookie: I can look into that, but it's probably the update to the taper code causing the error. If I recall correctly, the coordinate system for those B9 intake parts is different than the coordinate system for all the other stock and mod parts in existence, which is probably where the error is coming from.

@Pyromaniacal: Unless you're trying to launch 200 tonnes in one launch there's really no need to get KW rocketry or Novapunch; you can get by with stock and procedural fairings. There also aren't hotkeys for the control systems since I intended them to be used more for flying with the keyboard than a joystick; I can look into adding that, but I'll have to make sure they can be modified.

@Van Disaster: The reason drag gets worse when the intakes are closed is because of the way that intake drag seems to function. There doesn't appear to be a way for me to zero the "base" drag of the part without having to add entries to the ferramaerospaceresearch.cfg file, which is never going to be all-inclusive.

[Pyromaniacal]

Ah good. My KSP was starting to take a ridiculously long time to start anyway...

[Van Disaster]

@Ferram: would it work searching for a part named "Intake", in the way you do it for cargo bays ( if I understand right )?. Meanwhile I'll just patch it anyway, thanks for the tip.

Pyronamiacal: I use the bigger parts mostly to keep part count down for launchers rather than needing giant constructions.

[DuckZero]

I've searched the thread, but I can't find an answer, so sorry if this has been covered, but control surface assignment seems to do absolutely nothing. The angle of deflection works, but assigning to roll/pitch/yaw doesn't

[jrandom]

I've searched the thread, but I can't find an answer, so sorry if this has been covered, but control surface assignment seems to do absolutely nothing. The angle of deflection works, but assigning to roll/pitch/yaw doesn't

I haven't had any trouble with this. Maybe post a .craft file of a plane where this doesn't work for you?

[ferram4]

@Van Disaster: I don't think that would be possible; it seems like the ResourceIntakeModule class stores the "closed" drag value with too high a protection level for me to do anything with it. My only solution would be to create a new ResourceIntakeModule for each intake and then copy over every value that I can change, but that sounds complicated and prone to breaking.

@DuckZero: Are you actually assigning them properly? They start with all axes activated by default. If that's not the case, then please post a picture of the craft that has the problem, because no one else has had this issue.

[DuckZero]

@DuckZero: Are you actually assigning them properly? They start with all axes activated by default. If that's not the case, then please post a picture of the craft that has the problem, because no one else has had this issue.

Made a completely new craft from scratch.

All of the control surfaces actuate when rolling, even though only the standard control surfaces are assigned to roll. Similarly with other axes: as if it were just the stock behaviour.

http://i.imgur.com/ncMRmvT.jpg

http://i.imgur.com/2bxO2nE.jpg

[foamyesque]

Made a completely new craft from scratch.

All of the control surfaces actuate when rolling, even though only the standard control surfaces are assigned to roll. Similarly with other axes: as if it were just the stock behaviour.

http://i.imgur.com/ncMRmvT.jpg

http://i.imgur.com/2bxO2nE.jpg

I ran into that exact behaviour once before; it was caused when I changed FAR versions from one that did not use ModuleManager to one that did. Could that be your problem as well?

[taniwha]

ferram4: what with HL-subs being released, it would be wonderful if FAR could be extended below the water's surface. Would I be correct in guessing that the only major difference would be fluid density? While there's buoyancy, HL has that covered, and I'd consider things like cavitation to be icing, I think just some basics would make subs in a FAR enabled game more enjoyable.

My main problem is control surfaces do little or nothing underwater.

[ferram4]

@DuckZero: Post a copy of your output_log.txt and then try reinstalling FAR. If that doesn't work, right-click on the control surfaces and see if the "isShielded" flag comes up; if it does then FAR's PartModules are being applied correctly. Try saving the craft as something before launching, see if that helps. I honestly don't know what else to try since I've never seen this bug myself.

taniwha: Umm... I guess? Effects of Mach number wouldn't matter (yay incompressible fluids!), so that would actually simplify fluid dynamics for subs greatly. Then there would just be fluid density and some modelling of cavitation (mostly for the sudden drag increase when that happens). I'll admit that I've never done any hydrodynamic modelling, only aerodynamic modelling, so I'd have to put a lot of research into it first.

[Torminator]

Okay, I came across a really weird glitch/bug.

Built a rocket using the NovaPunch 5m parts and B9 winglet control surfaces. When in flight, the roll controls are reversed. The ailerons on the winglets oppose the RCS thrusters, and SAS/MechJeb tries to correct any rolling, but the reversal means it just intensifies. Any ideas? I'm launching four smaller pieces that each have probe cores and mechjeb units, so that may be the cause, but I've experienced a similar "death spin" with other large rockets. Tried adding a mk1 pod with Bob in it, and making sure it was set as the "control from here" but to no avail.

EDIT- Also, yaw controls don't seem to differentiate between control surfaces above and below the CoM. In other words, yaw acts more like "sideslip" with both surface moving the same way.

EDIT2- The roll issue was a result of the key controls for roll and yaw being the same. Not sure how that happened, but fixing it eliminated the roll issue. Yaw issue persists, but that's more likely to be something I'm doing wrong.

Edited August 26, 2013 by Torminator