Help Adding or Updating a motor file in OpenRocket.

[Wrightme43]

Hello,

I have a new Loki 670 Blue reload for my Loki 54/1200 case. I have the motor data from Thrust Curve but it does not seem to be a available motor in Open Rocket.

Does anyone know how to add a motor file, or update open rocket so that it is available?

https://www.thrustcurve.org/simfiles/66229756f873440002ab2cbc/

Thank you for your help!

Steve

 

[manixFan]

To add a motor to OpenRocket:

• download the motor data file – for the motor above it's in .eng format
• create a 'my motors' folder in your documents folder (you can name it anything you'd like)
• go to Preferences > General and look for User-defined thrust curves in the middle of the dialog box
• click the Add button to the right of the current location of user-defined files
• navigate to your custom folder and click the Add button
• quit and restart OpenRocket

I've found when adding motor files they don't always have the right maker assigned to them or will have other minor issues. I strongly suggest you verify the contents of the .eng file against what Loki shows on the website. It's not uncommon for the motor files to have errors.

Good luck!


Tony

This is the Mac version of the Preferences pane, which is under OpenRocket > Settings..., the windows version is under the Edit menu. You could copy your file to the location listed in the dialog box, but it's far easy for future maintenance to create your own folder in an easier to get to location:


Here's the motor imported into OpenRocket:

 

[Wrightme43]

To add a motor to OpenRocket:

• download the motor data file – for the motor above it's in .eng format
• create a 'my motors' folder in your documents folder (you can name it anything you'd like)
• go to Preferences > General and look for User-defined thrust curves in the middle of the dialog box
• click the Add button to the right of the current location of user-defined files
• navigate to your custom folder and click the Add button
• quit and restart OpenRocket

I've found when adding motor files they don't always have the right maker assigned to them or will have other minor issues. I strongly suggest you verify the contents of the .eng file against what Loki shows on the website. It's not uncommon for the motor files to have errors.

Good luck!


Tony

This is the Mac version of the Preferences pane, which is under OpenRocket > Settings..., the windows version is under the Edit menu. You could copy your file to the location listed in the dialog box, but it's far easy for future maintenance to create your own folder in an easier to get to location:
View attachment 677137

Here's the motor imported into OpenRocket:
View attachment 677133

You absolutely rock!!

And thank you again for the Motor cases!!

Steve

 

[Wrightme43]

Ok I have it added in, but the motor case is unpopulated, soooooo, openrocket thinks the motor is 3 feet long. Lol!

You wouldn't know how to convince it that it is in a 54/1200 case would you?

 

[Art Upton]

Ok I have it added in, but the motor case is unpopulated, soooooo, openrocket thinks the motor is 3 feet long. Lol!

You wouldn't know how to convince it that it is in a 54/1200 case would you?

Open the ENG file 'In Notepad' and change the item to 327mm here in the file.

 

[Art Upton]

I did not know this*, but looked it up here:
https://www.thrustcurve.org/info/raspformat.html

I still need to figger' out why the 'Case' Parameter 54/1200 is still missing


* I probably forgot 15 years or so ago

 

[Wrightme43]

Thank you Sir!

I will try that when I get home, work, then preach at one nursing home, then it is my Mom's birthday, at another nursing home.

I really appreciate all the help!

Steve

 

[manixFan]

Ok I have it added in, but the motor case is unpopulated, soooooo, openrocket thinks the motor is 3 feet long. Lol!

You wouldn't know how to convince it that it is in a 54/1200 case would you?

I've run into this as well when making my own motor files with my test stand. If you review the format for either the Rocksim .RSE format or the RASP .ENG file format, neither has a field for motor case size that I could find, and I could not figure out how to add one in. I looked through the github files to try and find the master motor database but it eluded me. Maybe @JoePfeiffer or another developer can help us out.


Tony

Motor file format sources:
http://wiki.openrocket.info/RSE_File#:~:text=Also called "RockSim XML format,the new RockSim XML format (.
https://www.thrustcurve.org/info/raspformat.html
And:
https://www.apogeerockets.com/education/downloads/Newsletter598.pdf

 

[ben]

I've run into this as well when making my own motor files with my test stand. If you review the format for either the Rocksim .RSE format or the RASP .ENG file format, neither has a field for motor case size that I could find, and I could not figure out how to add one in. I looked through the github files to try and find the master motor database but it eluded me. Maybe @JoePfeiffer or another developer can help us out.


Tony

Motor file format sources:
http://wiki.openrocket.info/RSE_File#:~:text=Also called "RockSim XML format,the new RockSim XML format (.
https://www.thrustcurve.org/info/raspformat.html
And:
https://www.apogeerockets.com/education/downloads/Newsletter598.pdf

It's my understanding OR is using the Thrust curve API for the motor data. Perhaps one can get case information thru the API. Unfortunately, OR binds the ThrustCurve motor data to the program.

 

[Art Upton]

It's my understanding OR is using the Thrust curve API for the motor data. Perhaps one can get case information thru the API. Unfortunately, OR binds the ThrustCurve motor data to the program.

It has to store the data locally as well. How else would you be able to use the program at a Rocket Launch long ago in a field far far away ?

 

[Art Upton]

Anyway the 'Length of the case' was an easy fix, putting in 327 or you could put in 330, but the Loki case is closer to 327. For some reason, the down loaded ENG file had 13xxx something in the spot and why it was 3+ feet long.

 

[JoePfeiffer]

I've run into this as well when making my own motor files with my test stand. If you review the format for either the Rocksim .RSE format or the RASP .ENG file format, neither has a field for motor case size that I could find, and I could not figure out how to add one in. I looked through the github files to try and find the master motor database but it eluded me. Maybe @JoePfeiffer or another developer can help us out.

John at thrustcurve.org maintains metadata for the motors that is not in the motor files themselves -- including the motor case. When we download the database from thrustcurve.org, we also pull that metadata.

We grab the database and store it in a "Java serialization data" file, which is not human-readable. It's in https://github.com/openrocket/openr...urces/datafiles/thrustcurves/thrustcurves.ser

Updating our database is one of the last things we do before a release, so it can be as up-to-date as possible. There's been occasional talk of having point releases to update the database, or having an easy way for a user to download a motor (with metadata) from thrustcurve.org, but neither one is likely to happen any time soon.

 

[Wrightme43]

Well I am not having any luck. It seems like the mass is correct, it seems like the sim is correct, it just looks crazy.

 

[manixFan]

Well I am not having any luck. It seems like the mass is correct, it seems like the sim is correct, it just looks crazy.

Here's what I get. I deleted all the sims in the file and ran just the J670 and the J525, which is pretty similar to the J670 in total impulse and weight. The two sims are pretty close, which seems reasonable. I modified one of my existing files to match your weight and length and my rocket sims were pretty close to those below, within a few hundred feet. (I set the flight conditions to standard atmosphere and 700' elevation to match my sims.)



Tony

 

[Art Upton]

I just opened it up, changed nothing.

J670


L1040

 

[kjhambrick]

Well I am not having any luck. It seems like the mass is correct, it seems like the sim is correct, it just looks crazy.

@Wrightme43 --

One thing about rocket.ork files with custom motor.eng files is that they don't share very well.

When you want to share a rocket.ork that includes your custom motor.eng file(s) you will also need to share your custom motor.eng files with the other user(s).

See below for the error dialog due to a missing custom motor.eng files ...

To load your sim with custom motor.eng files the sharee will need to install your custom motor.eng files as @manixFan outlined in post #2 above.

After all that, the sharee will need to close Open Rocket and reopen it with your rocket.ork that uses the custom motor.eng file.

Clear as mudd ?

HTH

-- kjh

This is the Error Dialog I see when trying to open your drago3xldualdeploy.ork in a running OP session:

 

[Wrightme43]

Thank you guys!

I will work on this again this evening after work. I really appreciate the help, and I will catch on.

 

[Art Upton]

@Wrightme43 --

One thing about rocket.ork files with custom motor.eng files is that they don't share very well.

Correct, and it works for me , as I had already downloaded and changed the 'length' of the motor in the ENG file yesterday.

 

[kjhambrick]

Ok I have it added in, but the motor case is unpopulated, soooooo, openrocket thinks the motor is 3 feet long. Lol!

You wouldn't know how to convince it that it is in a 54/1200 case would you?

Steve --

The Loki_J670LB-2.eng entry at ThrustCurve.org > J-670-LB has a motor length error:

Note that the length is incorrect in the .eng file.

Art explained how to fix the motor length in the downloaded Loki_J670LB.eng file with notepad but maybe @JohnCoker will fix the .eng file for future downloads if we tell him ( I just did that )

What a weird, scary intro to custom motor.eng files you chose

Anyhow ... as for the motor case metadata ...

I kinda like it that the motor case column is empty ... it makes it easier for me to find my custom motors



Note that 'my' Loki I-426-LB has no motor case so it is probably 'my' custom motor.

HTH[ 2 ]

-- kjh

EdIt: Thanks @Art Upton ! I was gathering screenshots for this post while you were reading my previous post

 

[Wrightme43]

Again, you guys are awesome, and I really appreciate all you do!

 

[Wrightme43]

Correct, and it works for me , as I had already downloaded and changed the 'length' of the motor in the ENG file yesterday.

View attachment 677451

I did this last night, BUT, I did not pay attention to the instruction CLOSE open rocket and RE-OPEN it. I expect when I get home and reopen it, it will work.

If not I will do it again, until I get it right.

 

[manixFan]

I did this last night, BUT, I did not pay attention to the instruction CLOSE open rocket and RE-OPEN it. I expect when I get home and reopen it, it will work.

If not I will do it again, until I get it right.

‘Rebooting’ is always the answer! Hopefully that’s all it was.


Tony

 

[neil_w]

I did this last night, BUT, I did not pay attention to the instruction CLOSE open rocket and RE-OPEN it. I expect when I get home and reopen it, it will work.

Yes, OR reads in the user motors when it first starts up. Any changes are only seen when the program is closed and reopened.

 

[JohnCoker]

Art explained how to fix the motor length in the downloaded Loki_J670LB.eng file with notepad but maybe @JohnCoker will fix the .eng file for future downloads if we tell him ( I just did that )

I fixed the length.

 

[kjhambrick]

I fixed the length.

Thanks, John and to all'y'all who have been participating in this educational thread !

P.S. I did mean to add in my earlier post that the author, John Junghans did an outstanding job digitizing the thrust curve data pairs

-- kjh

 

[Wrightme43]

Well I downloaded the file that John fixed, and it works perfectly.
It is still not a available motor in open rocket unless downloaded, but I expect that will fix when it is updated.

It is a super cool motor!

 

[Wrightme43]

And I want to say thank you all again for all the help!!!!

This place is full of amazing intelligent kind people!

Steve