Motor adapters in OpenRocket

[Azamiryou]

Is there a "best practices" standard for using motor adapters in OpenRocket?

1. Ignore it: I can select and sim smaller motors and just ignore the missing mass of the adapter and precise location of the motor. How much does this affect sim accuracy?

2. Separate rocket files for with or without adapter. Accurate, but what a pain! It's harder to compare simulations, and if you change the rocket design at all you have to update every file.

3. Motor files for motors with adapters. I like this solution, but each different adapter would need its own set of motor files. That could end up being a whole lot of data to sort through to find the motors you want! Plus if you design and make your own adapter, you'd need to make your own set of motor files...

What's the "best" approach? Is there a built-in capability I don't know about? Has anyone already made motor files with adapters?

 

[SolarYellow]

Another option might be a separate file for just the adaptor, and you can copy-paste the adaptor assembly into the file you want to use it in, then delete it when not needed. Still a PITA, but better than separate rocket design files.

Personally, I would LOOOVE to be able to turn parts or assemblies on and off within the .ork file.

 

[Scott_650]

I’m guessing, and it’s just a guess because my laptop is in the other room, that unless your adapter is packing some significant mass the difference between sims with and without an adapter are going to be pretty close to the random variations between any sim. I’ll have to play around and see what I get - I think I have the weights for my home built adapters and the Estes adapters in a notebook…or I can just reweigh them…

 

[Art Upton]

Is there a "best practices" standard for using motor adapters in OpenRocket?

1. Ignore it: I can select and sim smaller motors and just ignore the missing mass of the adapter and precise location of the motor. How much does this affect sim accuracy?

2. Separate rocket files for with or without adapter. Accurate, but what a pain! It's harder to compare simulations, and if you change the rocket design at all you have to update every file.

3. Motor files for motors with adapters. I like this solution, but each different adapter would need its own set of motor files. That could end up being a whole lot of data to sort through to find the motors you want! Plus if you design and make your own adapter, you'd need to make your own set of motor files...

What's the "best" approach? Is there a built-in capability I don't know about? Has anyone already made motor files with adapters?

I just do #1

 

[Buckeye]

Ignore it.

If you are running lots of motors, you are better off in Thustcurve, which includes an adapter option.

 

[Kane]

I use RockSim, but I assume you can do the same thing in Open Rocket: I place a mass object in the motor mount representing the adapter. I note the mass of the adapter in the object title. When simulating a motor that does not need the adapter, I set the mass to 0.001g. When simulating a motor that does need an adapter, I reset the mass of the object as noted in the title.
I don't like having separate rocket files. Since I am constantly tinkering, I don't want to have to change things in multiple files.

 

[thzero]

Another option might be a separate file for just the adaptor, and you can copy-paste the adaptor assembly into the file you want to use it in, then delete it when not needed. Still a PITA, but better than separate rocket design files.

Personally, I would LOOOVE to be able to turn parts or assemblies on and off within the .ork file.

GitHub.com/openrocket.

Feel free to contribute

 

[SolarYellow]

I'm no programmer.

 

[rharshberger]

Another option might be a separate file for just the adaptor, and you can copy-paste the adaptor assembly into the file you want to use it in, then delete it when not needed. Still a PITA, but better than separate rocket design files.

Personally, I would LOOOVE to be able to turn parts or assemblies on and off within the .ork file.

actually adding the option in the motor to use an adapter might be nice, then one file would do it all. If you have a 29mm with adapter check the box, if you have a 38mm without adapter dont check the box.

 

[bad_idea]

I made up a bunch of dummy motor files of various masses. I place a massless motor tube wherever I have a component that gets added, removed, or changed between various configurations (e.g., JLCR on some flights and not others, motor adapter, etc.). When I'm flying that component, I load the dummy motor of the appropriate mass into the massless motor tube and set ignition to "never." I get a warning that deployment occurred while a motor was still burning (which isn't the case - probably a bug I should file), but that can be ignored.

 

[NateB]

I ignore it. The 24/29 adapter weighs 7.6 grams. I wouldn't fly a motor so close to the minimum thrust needed to safely lift that difference in weight. I also figure the sim will be close enough, especially when you consider variances allowed from identical motors when they are certified.

 

[neil_w]

We have a plan to address this sort of thing. It is a very sensible request.

 

[Titan II]

Ignore

 

[Neutronium95]

I don't bother modeling them. If the mass is enough to make the difference between a stable flight and an unstable flight, then you didn't have enough stability margin. If you expect the mass to affect your choice of motor delay, any difference that amount of mass will make will be smaller than the natural variation in delay times.

 

[GaryDean]

I use RockSim, but I assume you can do the same thing in Open Rocket: I place a mass object in the motor mount representing the adapter. I note the mass of the adapter in the object title. When simulating a motor that does not need the adapter, I set the mass to 0.001g. When simulating a motor that does need an adapter, I reset the mass of the object as noted in the title.
I don't like having separate rocket files. Since I am constantly tinkering, I don't want to have to change things in multiple files.

That is exactly what I do for motor cases, motor adaptors, and trackers.

 

[Roo59]

I use RockSim, but I assume you can do the same thing in Open Rocket: I place a mass object in the motor mount representing the adapter. I note the mass of the adapter in the object title. When simulating a motor that does not need the adapter, I set the mass to 0.001g. When simulating a motor that does need an adapter, I reset the mass of the object as noted in the title.
I don't like having separate rocket files. Since I am constantly tinkering, I don't want to have to change things in multiple files.

I like this approach as a solid work around. There won't be any drag effects, so the main variable is accounted for.