modded KSP craft not working properly, please help dont know whats wrong

[Leonell12]

Hello fellow Kerbonauts!...I'm new to this forum and relatively new to KSP itself. Recently, i started a little project of mine, to make a spaceplane carrier!!! As BIG AS I COULD....KERBAL STYLE!!! But anyways i've managed to get a prototype that DOES fly, just not in a straight line. It keeps wanting to go to the right, both yaw and roll. I thought it was wheel barrowing first so i removed the 40 landing gears supporting the structure and took off with 'hack gravity' and then turned gravity on in flight, still the issue persisted. Dont know whats wrong. If someone could please check the craft for me that would be really nice of them. It's about 130 parts. Its constructed using the following mods in ksp 0.24.2.

Tweakscale

B9 Aerospace (The one with the gigantic HX modules)

Procedural wings

Interstellar mod

Infernal robotics

Maybe KW Rocketry, although only the 5m nose cones from that is used i think

Ferrum Aerospace

Kerbal joint reinforcement mod (or something like that)

Maybe Firespitter mod

I have no clue whats wrong with the craft. SAS doesnt keep it straight either. So i had to use the FAR flight assistance systems to keep it level and keep the yaw under control. That works and the craft definitely doesnt 'flip-out' which is good, but its not terribly manoeuvrable or even accurate in its turns, it yaws or rolls or pitches while turning.

If someone could help me out it would be really nice of them. I've spent hours on this thing.

Here's the Dropbox for it https://www.dropbox.com/s/x77xju4en3zx35t/bigger%20prototype%20TYPE-A.craft?dl=0

hope the link works

oh yeah, craft doesnt have any wheels or gears so yeah, no action groups whatsoever have been set, the infernal robotics is all manual for now

[Taki117]

*sigh* we really can't help you without pictures of your craft showing the relationship between your CoL, CoM and CoT. Very few people have all of those mods installed and are unwilling to download them just to download your craft and see what the problem is. My suggestion is to take a step back, and start small. I have a feeling since you are trying to do something overly complicated (Especially for a beginner) that you learn how to make good aircraft in FAR, then try to make good large aircraft in FAR, then worry about making an aircraft that will do what you want it to.

Now then, to answer your question I have a feeling it is a fuel flow issue.

[Leonell12]

right ok, well i'm sorry i didnt know that. Anyways, i was going to take a couple of screenshots today when having a closer look at the COT,COL and COM, i noticed that none of them apart from the COL were in the centre, they were off to the sides all of them. Thats why the craft kept going to the right, so i'm going to rebuild the whole thing from scratch and then tell you guys whats going on. Thnx for your help

[Leonell12]

*sigh* we really can't help you without pictures of your craft showing the relationship between your CoL, CoM and CoT. Very few people have all of those mods installed and are unwilling to download them just to download your craft and see what the problem is. My suggestion is to take a step back, and start small. I have a feeling since you are trying to do something overly complicated (Especially for a beginner) that you learn how to make good aircraft in FAR, then try to make good large aircraft in FAR, then worry about making an aircraft that will do what you want it to.

Now then, to answer your question I have a feeling it is a fuel flow issue.

hey, so i rebuilt the thing from scratch and it turns out it was just a bug due to a conflict between the interstellar mod and the new HX modules. The bug was that the COM and COT were not being calculated properly, for some reason they were off to one side, i moved a couple of parts around and everything seems to be working now. Thnx for your help. Can i just ask one question? How much Delta-V do i need to get to DUNA? i checked on google and apparently i need 7760m/s of delta v? http://wiki.kerbalspaceprogram.com/wiki/Tutorial:How_to_get_to_Duna i'm sorry for my ignorance but isnt Delta-v just acceleration? and so then how is an acceleration of 7760m/s possible? Can someone explain how this works to me?

[el_coyoto]

You can check a nice delta v map on the ksp wiki.

Delta V means velocity change, that you can picture as acceleration if you want. As in space, there is no air to slow you down, your ability to change your velocity says directly to which places you can go.

Edited October 8, 2014 by el_coyoto

[Leonell12]

You can check a nice delta v map on the ksp wiki.

Delta V means velocity change, that you can picture as acceleration if you want. As in space, there is no air to slow you down, your ability to change your velocity says directly to which places you can go.

right ok well on my craft, using kerbal engineer redux, my TWR using the thermal turbojets from interstellar mod is 7.91, and my delta-v is shown as 3 / 3m/s when the 'atmospheric stats' is on, without it the delta-v is 8 /8m/s. On the map you suggested, it'll take about 1400m/s of delta-v to get off kerbin, that value for some reason seems too high to me. oh and yes, the TWR on my craft seems to make no considerable difference to the delta-v...one more thing, what is delta-v exactly dependant on? I always thought it was the TWR, but now i'm beginning to think its the mass of the object.

Edited October 8, 2014 by Leonell12

[Taki117]

dV is dependent on how much of your craft mass is fuel and the efficiency of your engines. TWR is a measure of the amount of thrust you have vs the mass of your rocket. Also, if you have a TWR of more than about 4 for interplanetary travel it is way to high, while a higher TWR is good, generally speaking, in order to get such a high TWR you are using more powerful engines, which are typically less efficient.

dV explained simply: I have a rocket where half of the mass is fuel, and the engine has an efficiency of 1 which gives me a dV of 100. (This is an oversimplified example, in reality you would use the Rocket Equation)

If I increase the efficiency of the engine, or increase the mass of the fuel, my dV would increase. Conversely if I were to decrease engine efficiency or fuel mass my dV would go down.

Edited October 8, 2014 by Taki117

[el_coyoto]

right ok well on my craft, using kerbal engineer redux, my TWR using the thermal turbojets from interstellar mod is 7.91, and my delta-v is shown as 3 / 3m/s when the 'atmospheric stats' is on, without it the delta-v is 8 /8m/s. On the map you suggested, it'll take about 1400m/s of delta-v to get off kerbin, that value for some reason seems too high to me. oh and yes, the TWR on my craft seems to make no considerable difference to the delta-v...one more thing, what is delta-v exactly dependant on? I always thought it was the TWR, but now i'm beginning to think its the mass of the object.

TWR is "how hard can I accelerate?". This is mostly useful when taking off/landing (TWR ~= 2), and doesn't need to be very large when you are already in orbit or doing transfers, as Taki117 mentioned. It only means that you will need to burn longer for the same delta-v than a more powerful engine, but it shouldn't be a problem for most orbital manoeuvres, and can be as low as you are patient.

I posted a few tips on what affects your delta v and how to improve it in another thread, you may find it interesting.

Also, I'm not sure that KER isn't showing a buggy delta v for the interstellar turbojets, because 3 m/s in atmo and 8 m/s in vacuum seems awfully low, but as I've never played Interstellar (just watched Scott's Interstellar Quest) I'm don't really know...

[Leonell12]

Thank you all so much!! I just decided to ditch the interstellar turbojets and instead am using the DT-Vista engines. On the Delta-V it says almost 12000m/sec which should be enough to get me to Duna and back (which is where i plan to go, maybe Eve as well). So thanks guys so much for all your help! oh and yeah, turns out the reason for my weird COM, COT,COL was FAR getting confused with the big HX-modules that i'm using. If anyone knows how to fix that that would be helpful. But otherwise my problem's solved! thanks so much again.

Edited October 14, 2014 by Leonell12