Nose cones and aerodynamics

[Frameshift]

Hi,

I'm starting a new RP-1 game and have just noticed that nose cones are severely affecting my centre of lift, and not in a good way.  You can see in the first image I've got a cone shape off to the left and the CoM and CoL are fine.  As soon as I attach a cone shape to it like in the bottom image, my CoL goes crazy.  The same happens if I'm using a procedural part, any part, as a cone shape, or if I'm using a premade nose cone shape.

Anyone see this happen before?  Obviously it's a pretty heavily modded install.  I used the guide from Carnase to install RP-1 in 1.10.1 linked below,

Thanks,

James
 

[problematic image snipped by moderator]

 

Edited August 5, 2021 by Snark
Problematic image link snipped by moderator

[OHara]

Occasionally, FAR misunderstands the size and shape of modded parts from their configuration files. Sometimes the mod does tricky things with scaling that fools FAR and the mod cleans things up to be compatible with FAR;  other times FAR corrects the miscommunication:
https://forum.kerbalspaceprogram.com/index.php?/topic/182679-112x-restock-revamping-ksps-art-july-20/&do=findComment&comment=3554204

There is an option in the FARc menu, 'Transonic Design' => 'Display Debug Voxels', that shows the shape FAR is using.   (The option works in most versions of FAR, but for a couple versions of KSP, it shows me nothing.) 

Maybe there are error messages in the alt-F12 console that might identify the problem and help you solve it.

Look in the subforum for the mod that contains these parts, and in the FAR sub-forum, for anyone that might have had this problem.

[Snark]

Hi @Frameshift,

It looks like there was a problem with the image link you tried to post, such that the picture was, 1. not visible to anyone but yourself, and 2. causing issues with the forum formatting; so we've taken the liberty of snipping it.  It looks as though you may have been trying to link to an image that's hosted in your personal space somewhere, and which therefore nobody but you can see.  To post images in KSP forum posts, they need to be posted somewhere that is publicly accessible-- imgur.com is the most popular site that most people use, but there are plenty of others if you'd prefer those. 

Moving your post to Add-on Discussions, since this is about an issue with a mod.

[Frameshift]

5 hours ago, Snark said:

Hi @Frameshift,

It looks like there was a problem with the image link you tried to post, such that the picture was, 1. not visible to anyone but yourself, and 2. causing issues with the forum formatting; so we've taken the liberty of snipping it.  It looks as though you may have been trying to link to an image that's hosted in your personal space somewhere, and which therefore nobody but you can see.  To post images in KSP forum posts, they need to be posted somewhere that is publicly accessible-- imgur.com is the most popular site that most people use, but there are plenty of others if you'd prefer those. 

Moving your post to Add-on Discussions, since this is about an issue with a mod.

Thanks Snark, sorry I don't use these functions often...hopefully people can see the two images now.

Without nosecone

With Nosecone

12 hours ago, OHara said:

Occasionally, FAR misunderstands the size and shape of modded parts from their configuration files. Sometimes the mod does tricky things with scaling that fools FAR and the mod cleans things up to be compatible with FAR;  other times FAR corrects the miscommunication:
https://forum.kerbalspaceprogram.com/index.php?/topic/182679-112x-restock-revamping-ksps-art-july-20/&do=findComment&comment=3554204

There is an option in the FARc menu, 'Transonic Design' => 'Display Debug Voxels', that shows the shape FAR is using.   (The option works in most versions of FAR, but for a couple versions of KSP, it shows me nothing.) 

Maybe there are error messages in the alt-F12 console that might identify the problem and help you solve it.

Look in the subforum for the mod that contains these parts, and in the FAR sub-forum, for anyone that might have had this problem.

Thanks OHara,  I'll see if I can have a look at that information

[jimmymcgoochie]

@Frameshift That design isn’t a particularly good idea for an early RP-1 career- you don’t need RCS on it but you do need fins on the bottom to stabilise it, preferably rotated a couple of degrees to generate spin stabilisation and keep the correct end pointing to space, and making the nose pointy at the end is also a good idea. Clustering small engines like the Aerobees isn’t advisable, you’re much more likely to have an engine failure with many small engines than one big one and a single failure is likely to be terminal in either case.

What exactly is the purpose of this rocket? If you’re trying to do that film camera experiment flying low, stick it on a small plane instead and you’ll get much more range; for flying high or space low you should look at making something more like the V-2 with one of the V-2-derived engines (American A-4/A-9 or Soviet RD-100) which will give you a lot more performance than a cluster of Aerobees and which will make a good first stage to take you all the way through to orbit. 

[Frameshift]

Thanks for the advice Jimmy.  This was meant to be an example of how the addition of a tiny nose cone drastically changes the CoL, more than what I thought should happen, not a rocket that  is terribly well designed   

And I'm not playing with Testflight so clustering is fine.  I dislike the engine reliability thing, too much time wasting.