Problems with custom motors in OpenRocket

[kencraw]

I'm having trouble being able to open/view custom motors in OpenRocket. I've followed the directions I've seen here on TRF but just haven't had any luck. What I've done is I've placed a .rse file in a known folder and then under Edit -> Preferences -> Options (tab) -> User-Defined thurst curves, entered both the directory where the file is stored and directly the file itself. In neither case can I get it to show up in the list of motors, when I click "Select motor" from the "Motors & Configuration" tab of the main screen. Is there something I'm doing wrong?

I've attached the file I'm trying to import. I think it might be the contents of the file, because looking at the debug log I see:
(MotorDatabaseLoader.java:102) IOException while reading E:\Documents\Rockets\ThrustCurves\water90.rse: java.io.IOException: Illegal motor data

Can someone tell me what is wrong with that file?

I'd also appreciate it if someone could attach a file to a reply in this thread that they KNOW works in OpenRocket (and ideally one that is not one of the already included motors because as I understand it correctly, the included ones mask the custom ones), so that I can test a known good file.

Any help anyone can provide is appreciated.

View attachment water90.rse

 

[teyrana]

First Error found: The .rse file you posted declares its C.G to be outside the motor (i.e. farther than the motor length). Increasing the length to 200 solves this problem.

BUT it uncovers a problem with negative mass. I'm researching how that works now.

-DW

 

[kencraw]

Thanks Teyrana. Looks like I'm going to have to dig into the details of how these files work so I can debug these issues myself. Out of curiosity, how did you determine the C.G. issue? Was it "by hand" or did you have some SW/tool that made it clear to you?

 

[teyrana]

Thanks Teyrana. Looks like I'm going to have to dig into the details of how these files work so I can debug these issues myself. Out of curiosity, how did you determine the C.G. issue? Was it "by hand" or did you have some SW/tool that made it clear to you?

Tools: The JDK, eclipse, and Git

Procedure: Actually I pulled the latest source code, and debugged the file from the java code itself. I actually modified some of the thrown exceptions, because they were too vague.

And then I looked at the file itself, and applied what few brain cells I have left -- if you look at the list of "eng-data" tags, each has an entry for time (t), force (f), mass (m), and center of gravity (cg). (Although that SHOULD be center of mass, but i'm being pedantic.)

compare each of those with the tags in the "<engine..." header, and the progression should make sense.

p.s. I'm still figuring out what the units are... let me know if you have a good documentation source for these .rse files. The OpenRocket wiki has a rather bare page, but please feel free to expand on it. (https://wiki.openrocket.info/RSE_File) )

p.p.s. I should have time to dig further next week, if you're not in a hurry...

 

[Right Wing Wacko]

Tools: The JDK, eclipse, and Git

Procedure: Actually I pulled the latest source code, and debugged the file from the java code itself. I actually modified some of the thrown exceptions, because they were too vague.

And then I looked at the file itself, and applied what few brain cells I have left -- if you look at the list of "eng-data" tags, each has an entry for time (t), force (f), mass (m), and center of gravity (cg). (Although that SHOULD be center of mass, but i'm being pedantic.)

compare each of those with the tags in the "<engine..." header, and the progression should make sense.

p.s. I'm still figuring out what the units are... let me know if you have a good documentation source for these .rse files. The OpenRocket wiki has a rather bare page, but please feel free to expand on it. (https://wiki.openrocket.info/RSE_File) )

p.p.s. I should have time to dig further next week, if you're not in a hurry...

The RASP format is documented by Apogee in Peak-of-Flight E-zine Newsletter #139 (https://www.apogeerockets.com/education/downloads/newsletter139.pdf)



.

 

[JohnCoker]

You may find it easier to hand-create RASP format files. Or, if you're working from a printed thrust curve, you might to try my TCTracer program.