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

[ferram4]

@foamyesque: If that's for the 3-man pod, then the last number should be a 2, not a 1.

[SchroedingersHat]

@foamyesque: If that's for the 3-man pod, then the last number should be a 2, not a 1.

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.

Edited June 23, 2013 by SchroedingersHat

[Stinkyhair]

How do prevent FAR from opening pop ups all over the -snip- screen?

I like the idea of having a more accurate model for simulating in-atmosphere flight but the popups piss me off to no end.

Edited June 24, 2013 by KasperVld

[ferram4]

@SchroedingersHat: I honestly don't know what to do for that one. I haven't coded anything to work with that try of behavior yet.

@Stinkypubes: Click the button at the top of the main window. That will minimize it to just the button.

[Stinkyhair]

That doesn't stop FAR from opening NEW popups every time I go to launch or open the vehicle assembly building

[ferram4]

Well, then uninstall it. The windows start open by default.

[Chestburster]

Is it possible to make the window in VAB/SPH remember its position and state? It's something that is bothering me for some time now xD

[Stinkyhair]

Yeah I'm with chestburster, why -snip- should I have to uninstall a useful mod just because of a bad UI the dev refuses to fix?

Edited June 24, 2013 by KasperVld

[SchroedingersHat]

@SchroedingersHat: I honestly don't know what to do for that one. I haven't coded anything to work with that try of behavior yet.

Would there perhaps be enough flexibility in telling FAR to treat it as a wing to make it behave somewhat correctly? I tried looking up some of the coefficients in the cfgs, but they're too short to google for the most part and I've yet to work up the motivation to read an entire textbook on aerodynamics.

I've encountered a number of other objects that act a little odd. One of the most recent was a Hooligan Labs airship that rocketed off at hypersonic speed. Playing with its mass/buoyancy (to bring it closer to realistic proportions, although it then becomes hard to fit an airship with decent payload in the VAB or SPH) as well as increasing node size made it behave as I expected an airship to, but they don't all have nodes on top.

Yeah I'm with chestburster, why -snip- should I have to uninstall a useful mod just because of a bad UI the dev refuses to fix?

I obviously works well enough for ferram, and he/she's kind enough to share such great work. There is also other stuff to do on the mod so rather than getting abusive, ask nicely and be patient or grab the source, go find a programming tutorial and offer a patch.

That being said, I would appreciate a few small changes to the UI. I seem to frequently lose the button behind something else or completely off screen (esp when changing resolution) and have to go change it in the config. Other mods seem to be moving towards having one small iconic button somewhere that stays on the edge of the screen and everything else off by default.

Edited June 24, 2013 by KasperVld

[ialdabaoth]

farram4, if I were to rewrite your UI to be less obnoxious, would you be interested?

[MR4Y]

@MR4Y impressive! What mod are using for the wings there? It looks to me like you using Damned Robotics but then the wings fit around that part so nicely if that is the case.

DYJ's Procedural Wings.

[ferram4]

@Stinkypubes: You do realize that I'm more focused on the physics than the UI, right? If it bothers you that much, you can go into the source code provided with the download and change it yourself, but it's not a priority. I would like to update it though, but I haven't gone through mods that have GUIs that I like to find example code yet.

@SchoredingersHat: I really don't know if I'd be able to handle the Hooligan Labs airships properly, especially since they don't seem to be all that realistic in terms of the payloads they can lift. They just strike me as incredibly cheap and I'm not going to put too much work into having realistic aerodynamics apply to a cheap mod.

Trying to model the deployable heatshield as a wing is a definite no. Wouldn't act anywhere near that. The main problem is trying to come up with the code to handle the change in drag, lift and moment coefficients due to deployment.

@ialdabaoth: Sure, go ahead. It'll probably come out better than anything I'd come up with.

[SchroedingersHat]

@SchoredingersHat: I really don't know if I'd be able to handle the Hooligan Labs airships properly, especially since they don't seem to be all that realistic in terms of the payloads they can lift. They just strike me as incredibly cheap and I'm not going to put too much work into having realistic aerodynamics apply to a cheap mod.

Dividing the payload by 100 and the mass by a 10 made them more airshippy. I wasn't even thinking about the deployable airships, more thinking along the lines of a way of telling FAR 'this is a big thing and it should produce more drag' about the rigid ones (and various other objects)-- I don't know if this exists already but it seems to come up reasonably frequently. The airships also have some odd-ness with collisions so maybe that has something to do with it?

[espm400]

If you aren't afraid of clipping parts together, you can closely approximate a lifting body using FAR and Procedural Wings. Just increase the pWings' root size until the fuselage mostly disappears inside, and blend the two structures together with smaller pWing pieces. The result will look and fly very much like a true lifting body.

I'll try that out, thanks. I managed some proof of concept ones with the B9 Aerospace pack with just the wing parts (I have pWings, but never though to try that). They're hard to build and control, but they work, although they're ugly as sin. I actually had one that I was just testing the body out, it had no control surfaces what-so-ever, but somehow managed to stay aloft for the entire duration of it's fuel (about 4-5 mins.). I think in my free time I'm going to do some self-education with Unity as well as with creating meshes to create some proper pods and such.

P.S. I don't know why I've all of a sudden got an obsession with these things, I've known about them since I was a kid...

[Xechran]

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 followed your post here from the DR thread last night, checked the wiki and it says node attachment size range is 0 for half meter, 1 for the mid size 1.25 meter, and 2 for the 2.5 meter nodes. The size parameter is optional and it assumes 1 if no value is given... I'm poking around in KW and it seems like a lot of things dont have a node size specified. The service engine, for example, is given node size 2 but the griffonXX "the largest engine available" doesnt have a size specified, so its actually only size 1?

name = KW3mengineGriffonXX
description = The most powerful engine availible, capable of launching large rockets without the aid of solid boosters or additional cores at the cost of fuel efficiency.

// --- node definitions ---
node_stack_top = 0.0, 2.808, 0.0, 0.0, 1.0, 0.0
node_stack_bottom = 0.0, -0.491, 0.0, 0.0, 1.0, 0.0

The 3.75 and 6.25 meter heat shields in deadly are also set to size 1 if Im reading this all right.

// --- node definitions ---

// definition format is Position X, Position Y, Position Z, Up X, Up Y, Up Z

node_stack_top = 0.0, 0.4548836, 0.0, 0.0, 1.0, 0.0, 1

node_stack_bottom = 0.0, -1.02125, 0.0, 0.0, 1.0, 0.0, 1

Seems like I may have a date with GVim.

[Pixel of Life]

Something must be wrong with the mod. I haven't been able to get a single rocket to orbit after I installed it! ALL of them flip at some point during the ascent, almost always between 5km and 10km and at around 300 m/s. I've tried with ASAS and Mechjeb, I've tried flying manually, with yaw and pitch dampers on and off, but the rockets simply refuse to fly where they are pointed. It almost feels like after passing a certain speed and/or altitude, laws of physics turn upside down and the rocket doesn't want to point in the direction of travel anymore.

Here is a picture of one of my rockets. It's got a pointy tip and fins at the opposite end, but why the hell does it not fly properly?

[The Lone Wolfling]

Something must be wrong with the mod. I haven't been able to get a single rocket to orbit after I installed it! ALL of them flip at some point during the ascent, almost always between 5km and 10km and at around 300 m/s. I've tried with ASAS and Mechjeb, I've tried flying manually, with yaw and pitch dampers on and off, but the rockets simply refuse to fly where they are pointed. It almost feels like after passing a certain speed and/or altitude, laws of physics turn upside down and the rocket doesn't want to point in the direction of travel anymore.

Here is a picture of one of my rockets. It's got a pointy tip and fins at the opposite end, but why the hell does it not fly properly?

[snip]

What's the rocket's thrust-to-weight ratio? With FAR you should have much lower TTW in general, I've found. Rockets are often aerodynamically unstable to begin with, and if it's traveling too fast through thick air good luck controlling it.

Also, your center of mass might be too low.

[verikosto]

Hi! im just here to ask couple of question about rockets in FAR. SO i always used in vanilla the big rocko max engines for fast delivery to space and now im asking you whats the best rocket to strap on my desings? (sorry about my bad english)

[Pixel of Life]

What's the rocket's thrust-to-weight ratio? With FAR you should have much lower TTW in general, I've found. Rockets are often aerodynamically unstable to begin with, and if it's traveling too fast through thick air good luck controlling it.

Also, your center of mass might be too low.

The TWR of the first stage (it flips before I have to activate stage 2) is 2.5. CoM is located at the height of the letter E in the fuel tank.

[Greywind]

CaptainKorhonen don't blame the mod so quickly? If you are used to stock then this is a big change. I spent a couple hours trying to work out how to make rockets fly again. Some of the big things are TWR, like mentioned, and starting your gravity turn even earlier (for me it is around 500m when i start). With mechjeb, try using throttle control to reduce it, or use less thrust, then set your turn accordingly. And verikosto, the "best" rocket is really hard to determine, everyone plays the game a little differently. What are you trying to send into space? The mainsail can still fly well with FAR, but it is very powerful, maybe use a skipper; and again, watch the TWR or your rocket will be unstable.

[WedgeJAntilles]

You're flipping around because your center of drag is in front of your center of mass, so air resistance at high speeds often causes you to flip around. Ferram posted some good tips for dealing with this few pages back; I won't repeat them here. I will suggest in short that you limit your acceleration to 20 m/s (use mechjeb's throttle assistance for this, it's a lifesaver) and turn slowly so you get out of the lower atmosphere as quickly as possible. Once you're at 35km, you'll be perfectly fine.

I will add that if you have a large, light payload, your CoD will be SO far ahead of your CoM that even that won't help. It took me awhile to figure it out, but here's what I figured out:

* Contrary to normal, it helps to make your rockets SHORT and WIDE -- asparagus staging is good here.

* Climb straight up until the atmosphere is thin enough that you can turn without losing control. This is usually at LEAST 15km. Even with such a non-optimal gravity turn, it still takes less delta-v to reach orbit than it does without FAR.

I will say that I feel your pain. It took me a good couple of weeks of failed launches and rockets flipping upside-down before I worked out how to get consistent launches with FAR, but it IS possible.

Edited June 24, 2013 by WedgeJAntilles

[asmi]

I always control my rocket "semi-automatically" (Using Smart ASS's "Surface" mode) and always set pitch 88 and needed launch heading (btw I use 350 for polar orbits) before liftoff, then slowly turn it so by the time I get to 3k I'm at 80 pitch. I always keep TWR low (1.2..1.6), do not even attempt to control the rocket while it's transonic (keep it at whatever P/Y/R it happened to be once it hit 0.85M until about 1.2M), pass through MaxQ at around 1.4M, then throttle down until the staging and keep turning so I'd hit orbit of about -10km by whatever target orbit is (usually 75-80).

Also it really helps to NOT have any staging events during initial ascent, so I usually try to avoid using SRBs as they often cause flips (their TWR becomes too high as they burn out, and I can't shut down sustainer as this will leave rocket without any control autority). I use KW Rocketry as main toolchain for building rockets, so I try to build sustainer core so it would last all the way through ascent (to -10x<target_alt>) by ensuring it (and boosters, if any) has about 3000 m/s dV, while still making it off the pad (TWR > 1.2, lower TWRs yields too much gravity losses).

[Pixel of Life]

CaptainKorhonen don't blame the mod so quickly? If you are used to stock then this is a big change. I spent a couple hours trying to work out how to make rockets fly again. Some of the big things are TWR, like mentioned, and starting your gravity turn even earlier (for me it is around 500m when i start). With mechjeb, try using throttle control to reduce it, or use less thrust, then set your turn accordingly.

Would you not blame the mod if you spent countless hours building rockets that look completely normal and should work, yet they don't?

I actually found a solution, but only after reading the readme when I installed the newest version. It was my mistake, I was overspeeding and the control surfaces lost their effectiveness. I tried staying at around 150 m/s all the way up to 10km and then a very gradual acceleration and gravity turn and everything worked brilliantly.

[foamyesque]

The TWR of the first stage (it flips before I have to activate stage 2) is 2.5. CoM is located at the height of the letter E in the fuel tank.

Your CoM is too low.

Quite honestly 99% of the problems people have with rockets in FAR are a direct result of turning too sharply, going too fast, or being bottom heavy.

[ferram4]

@CaptainKorhonen: A TWR of 2.5 at launch is way too high. Try to lower the TWR to something like 1.2 - 1.4 at launch.

The second problem is that if your CoM is that close to the back of the rocket then your payload doesn't weigh anything; whatever's underneath that fairing isn't contributing enough to the mass distribution of the rocket to balance out the fairing's contribution to the location of the CoD. If necessary, add dummy payload weight to be ditched with the payload fairings to balance it out.

Finally, it's possible that the mod parts are not set up correctly; FAR uses the size of the attachnodes to calculate drag caused by the base of an engine, uncovered fuel tanks, etc. 0.625m parts use size 0, 1.25m parts use size 1, 2.5m parts use 2, 3.75 use 3, etc. If that isn't set up properly then the engine will not make the drag it is supposed to, shifting your CoD further forward than it is supposed to be.

@verikosto: The best rocket engine to put on your rockets is whatever will just barely get it off the ground at launch. If you use something too powerful then you risk losing control of the rocket during launch.