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[1.3.0] OPT Space Plane v2.0.1 - updated 29/07/2017


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17 hours ago, K.Yeon said:

I tried this when i first made those wings but it doesn't work because the control surface doesn't get mirrored the correct way :( The current configuration is the only way it works... perhaps i will re make the wings to make them easier to attach in the distant future.

OPT is simply a parts pack, it doesn't causes crash. Without a log, i can only suspect it maybe caused by outdated firespitter or RPM?
Post the last couple of hundred lines of the ksp log file (Steam\steamapps\common\Kerbal Space Program\KSP.log) right after you encountered a crash, it usually tells the cause.

ok, so i deleted firespitter and installed modular fuel tanks instead thinking that would fix the problem but it crashed again, i found the crash file, do you want me to post it here?

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On 2/8/2017 at 6:34 PM, stali79 said:

I have the issue with stock, but I just get creative in wing placement.  What I struggle with is getting my CoL behind my DCoM

 

https://kerbalx.com/stali79/craft

doesn't this count as.. kind of a serious usability problem?  The lack of a way to build an aerodynamically stable craft (with FAR or stock, apparently) due to body lift that is significantly higher than stock or Mk4 parts seems like something that could/should be addressed?

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21 minutes ago, ss8913 said:

doesn't this count as.. kind of a serious usability problem?  The lack of a way to build an aerodynamically stable craft (with FAR or stock, apparently) due to body lift that is significantly higher than stock or Mk4 parts seems like something that could/should be addressed?

Yes and no. For me it provides challenge to make my birds fly

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50 minutes ago, ss8913 said:

doesn't this count as.. kind of a serious usability problem?  The lack of a way to build an aerodynamically stable craft (with FAR or stock, apparently) due to body lift that is significantly higher than stock or Mk4 parts seems like something that could/should be addressed?

 

28 minutes ago, stali79 said:

Yes and no. For me it provides challenge to make my birds fly

For OPT wings, i use liftvalue=z*0.284,  (z is the topdown projection area by the part) This is the same calculation as stock wing parts.
For OPT J parts, i use liftvalue=z*0.284*0.35, because the fuselage is curved it's less effective at producing lift
For OPT K parts, i use liftvalue=z*0.284*0.55, to be honest i wanted to use 0.80 because i often think the k parts is just a very thick wing. But i used 0.55 to make them more usable ingame.

If you have a better way of balancing the lift value please let me know. Because this model isn't 100% accurate, but for that matter stock aerodynamic isn't 100% accurate aswell, so i think the current liftvalues does make sense.

When you said you can't build aerodynamically stable craft, i assume you mean your craft's CoL is always in front of CoM? This is very common because most of the engines are very heavy compare to the fuselage, causing the CoM to shift behind. The easiest way to fix this is give your aircraft large delta wings, just take a look at the prebuilt OPT aircrafts, all of them are pretty stable.

You might ask why this problem isn't obvious when using stock mk2, this is because the mk2 fuselage is very small relative to the stock wing parts, so most people automatically add more wings to their crafts, and the lift produced by the wing overshadows the lifting body lifts.

If you have a mk2 design that's aerodynamically stable, scale the wings and engines twice as large (using tweakscale), and replace the mk2 fuselage with J fuselage, i can guarantee the new craft is also aerodynamically stable.

But like i said before, if anyone knows the correct way (stock way) of balancing lifting body parts im always open to change to a more accurate model.

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This stability problem is one of the pitfalls that prevent the use of wide bodies in real aircraft since the wide surface generates lift with no means of controlling it, they build them taller but rarely do they build them wider, and where it is used like the B2 or a variety of experimental aircraft that combine fuselage and wing they usually have a large delta wing arrangement pushing the engine mass further forward and the CoL further back, while being heavily reliant on computer augmented stability control. Perhaps a wing set with a deeper delta sweep is something to consider at some future date.

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Maybe I can make something work with B9 procedural wings.. if i sweep them way back behind the fuselage or something.

UPDATE: no.. that doesn't work.  still can't get the CoL back far enough.

Edited by ss8913
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Dunno 'bout no stability problems. OPT planes are easy. Here's my Manta series - taxi, bus and delivery crafts near new orbital station. All are ironclad stable during accent (pitch 25 degrees after lift off and chew snaks, don't forget to circularize after though). Descent and landing is also easy enough, even I can manage it after all, and I am really bad pilot, 'specially in stock aero. 
 

Spoiler

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22 hours ago, M_Ouellette said:

This stability problem is one of the pitfalls that prevent the use of wide bodies in real aircraft since the wide surface generates lift with no means of controlling it, they build them taller but rarely do they build them wider, and where it is used like the B2 or a variety of experimental aircraft that combine fuselage and wing they usually have a large delta wing arrangement pushing the engine mass further forward and the CoL further back, while being heavily reliant on computer augmented stability control. Perhaps a wing set with a deeper delta sweep is something to consider at some future date.

Modern fighters such as f-15 or russian MiGs and SUs utilize lifting body composition providing up to 40% of total lift with their fuselage.

Edited by TheIV
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On 2/11/2017 at 7:44 AM, TheIV said:

Dunno 'bout no stability problems. OPT planes are easy. Here's my Manta series - taxi, bus and delivery crafts near new orbital station. All are ironclad stable during accent (pitch 25 degrees after lift off and chew snaks, don't forget to circularize after though). Descent and landing is also easy enough, even I can manage it after all, and I am really bad pilot, 'specially in stock aero. 
 

  Hide contents

vVsd2wx.jpgqtqCnNi.jpgOGI7IVy.jpguomGITz.jpg

 

Modern fighters such as f-15 or russian MiGs and SUs utilize lifting body composition providing up to 40% of total lift with their fuselage.

I think it must be a FAR thing then.  No way would anything shaped like this be properly balanced with FAR.  ie, if I put a J cockpit followed by 3 4m modules and then a tailpiece, at this point the CoL is just behind the *cockpit*.  I don't think that's how it should be.  I think FAR's voxelation of the OPT parts is putting the CoL a lot further forward than stock aero is.  I'll wait until FAR's full release and then post some stuff, since I don't think K.Yeon wants to debug things off a dev build of FAR :)

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5 hours ago, ss8913 said:

I think it must be a FAR thing then.  No way would anything shaped like this be properly balanced with FAR.  ie, if I put a J cockpit followed by 3 4m modules and then a tailpiece, at this point the CoL is just behind the *cockpit*.  I don't think that's how it should be.  I think FAR's voxelation of the OPT parts is putting the CoL a lot further forward than stock aero is.  I'll wait until FAR's full release and then post some stuff, since I don't think K.Yeon wants to debug things off a dev build of FAR :)

Well, FAR is not stable as of now so I stuck with stock aero until official release. Also OPT needs a patch for FAR, at least there were for previous versions.

And on the question of balance - use the power of your creativity: move parts around, rotate them, use more wings at the back of the craft. Add more stability control if nothing helps. OPT parts are OP as hell and that is why I like this mod (RIP mk2 scramjet. You were the awesomest).

Spoiler

7uO6sDx.jpg  


 

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On 2/13/2017 at 5:11 AM, TheIV said:

Well, FAR is not stable as of now so I stuck with stock aero until official release. Also OPT needs a patch for FAR, at least there were for previous versions.

And on the question of balance - use the power of your creativity: move parts around, rotate them, use more wings at the back of the craft. Add more stability control if nothing helps. OPT parts are OP as hell and that is why I like this mod (RIP mk2 scramjet. You were the awesomest).

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7uO6sDx.jpg  


 

going to wait for the FAR update/associated patching after that happens.  I don't think the aero on the OPT parts currently makes sense as intended, but I'm willing to believe that it does as far as stock aero is concerned.  The previous FAR patches for OPT were regarding the wings; the lifting bodies always worked before prior to the 1.2.x releases, so I'm hoping after FAR is official, this mod can update to work the way that it used to.  Currently I can find no way, even with procedural wings, to get the CoL far enough back.  It's not really an issue with moving the CoM forward as much as it is with moving the CoL back, since the CoL is, what I consider to be illogically far forward; almost like the cockpit itself is generating multiple times as much lift as any of the other parts.  I should do some tests on that using non-OPT cockpits and see at least what results I get in the SPH...

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On 14.02.2017 at 11:23 PM, King Something said:

Any OPT parts (other than wheels) not in the main pack are probably in the Legacy pack. The Mk2 Scramjet engines are among those parts.

Isn't Legacy pack outdated? Had Some problems with it couple of months ago and don't use it since.

15 hours ago, ss8913 said:

Currently I can find no way, even with procedural wings, to get the CoL far enough back.  It's not really an issue with moving the CoM forward as much as it is with moving the CoL back, since the CoL is, what I consider to be illogically far forward; almost like the cockpit itself is generating multiple times as much lift as any of the other parts.

CoM should still be roughly in the middle of your craft or you risk to summon some crazy transsonic flips. It is also obvious that moving CoM closer to front make it easier to move CoL behind it...  Can you maybe post screenshot with markers from SPH?

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3 hours ago, TheIV said:

Isn't Legacy pack outdated? Had Some problems with it couple of months ago and don't use it since.

CoM should still be roughly in the middle of your craft or you risk to summon some crazy transsonic flips. It is also obvious that moving CoM closer to front make it easier to move CoL behind it...  Can you maybe post screenshot with markers from SPH?

Depends on what you mean by outdated.

If it's just complaining that "this mod is for a previous version", that's just because Stali79 hasn't bothered updating the version info and making a new release. 

Aside from that, the parts basically come in three categories:

1. Parts that work, but don't fit where K.Yeon wants to take the mod currently (like all the engines)

2. Parts that don't work as intended due to game issues (the old wings, some of the ramps and cargo sections)

3. Parts that work with a little bit of help, such as Kerbal Joint Reinforcement System (the Humpback fuselage, maybe some of the other legacy fuselage profiles). 

Personally, I only use the engines and the Humpback fuselage as none of the extra things for the Stail and Avatar fuselages that don't exist for J and K appeal to me aesthetically, and the core functionality of J is much greater than for the Stail (old J) parts due to being just slightly larger, and of course all of the parts working in the current game. The rest of the truly obsolete parts (the wings etc) I could probably delete without much trouble. 

 

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5 hours ago, Alexology said:

Sorry I could not find this anywhere but there are 101 pages to read through. I am using a fair number of mods so I wanted to ask before I added this. Will this fit in with the community tech tree? 

yes

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13 hours ago, TheIV said:

Isn't Legacy pack outdated? Had Some problems with it couple of months ago and don't use it since.

CoM should still be roughly in the middle of your craft or you risk to summon some crazy transsonic flips. It is also obvious that moving CoM closer to front make it easier to move CoL behind it...  Can you maybe post screenshot with markers from SPH?

I'll post a screenshot later.  It's... REALLY far forward.

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I've been having a similar problem with my attempts to build a spaceplane around a J hull. The CoL stays more or less in the middle of the plane due to the lifting effects of the body segments, but the CoM and DCoM are shifted way to the rear due to the engines and the comparatively light mass of the empty J segments. 

I even built an SSTO with a J core and Mk 2 outriggers that massed about 70 odd tons and would have flown quite well using only the Large pylons for wings due to massive amounts of lift from the J body segments, except that the CoL was so far forward that to bring it back to the CoM at the rear of the plane required me to shift the control surfaces back so far they where in an entirely different town from the body.

 

 

Spoiler

 

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So I've been messing around more with the OPT parts pack. For a test I took a standard J cockpit, switched the fuel tanks to LFO, stuck 3 of the fixed landing gear on it and a couple of small radial engines to give it some thrust and took it for a flight. No control surfaces, no wings, just the reaction wheels for flight control.

It actually flew quite well. It had terrible crabbing issues and no real Yaw authority, but the thing is that just the basic lifting force of the cockpit itself was enough to make it a pretty good glider. In fact I had difficulty landing it because it glided so well.

I tried a slight mod to this next. I added some standard control surfaces to the baseplate of the cockpit, Enough for 3 axis control and took it out again. It flew much better than before, even better still when I turned the reaction wheels off.  I buzzed all over the KSC with it, though it will never be a stunt plane. I've attached the craft file below.

This suggests to me that your parts are generating too much lift. I don't think a 3.5 ton cockpit with a couple small rocket motors on it should be able to fly without the assistance of wings. 

 

 

On 17/02/2017 at 1:24 AM, stali79 said:

Maybe the engines need to have their weights reduced to push the CoM and DCoM forwards

Fixing a mod by changing all the other parts in the game is not the solution.

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1 hour ago, Magnavox said:

So I've been messing around more with the OPT parts pack. For a test I took a standard J cockpit, switched the fuel tanks to LFO, stuck 3 of the fixed landing gear on it and a couple of small radial engines to give it some thrust and took it for a flight. No control surfaces, no wings, just the reaction wheels for flight control.

It actually flew quite well. It had terrible crabbing issues and no real Yaw authority, but the thing is that just the basic lifting force of the cockpit itself was enough to make it a pretty good glider. In fact I had difficulty landing it because it glided so well.

I tried a slight mod to this next. I added some standard control surfaces to the baseplate of the cockpit, Enough for 3 axis control and took it out again. It flew much better than before, even better still when I turned the reaction wheels off.  I buzzed all over the KSC with it, though it will never be a stunt plane. I've attached the craft file below.

This suggests to me that your parts are generating too much lift. I don't think a 3.5 ton cockpit with a couple small rocket motors on it should be able to fly without the assistance of wings. 

Hmmm, i must say the cockpit is quite aerodynamic, but you are right, it shouldn't glide as well as it does now...
Also i think all of the current cockpit have very over powered reaction wheel, and your craft uses the cockpit as the whole fuselage, it could be a factor why it's gliding well.

Now i have a few things that im certain that i will rebalance:
1, the lift values, will be lowered
2, the reaction wheel, it's pitch and yaw should be lowered
3, i will move the engine's CoM forward, (since the actual body of the 2.5m and dark drive engine isn't represented)
 

Edited by K.Yeon
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Hi K.Yeon,

I have recently building spaceplanes with your parts and still love them. However there is one kind of part I feel to be missing that would perfectly match in the set. Its OPT-J to MK2 Bicoupler and Tricouplers. Since the J fuselage height is pretty much the MK2 width three in row would match perfectly. Might be the ideal mount for MK2 expansion engines and such. I would have tried to model them myself but cant find the model sources anywhere.

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