Happy to do a Skype at some time that I'm awake in Australia and run you through the process loop...... PM me.I have tried OR several times and have gotten nowhere so I gave up and do my own thing. The last time I made a spread sheet was 2002.
Happy to do a Skype at some time that I'm awake in Australia and run you through the process loop...... PM me.I have tried OR several times and have gotten nowhere so I gave up and do my own thing. The last time I made a spread sheet was 2002.
The only real way to determine CG is to actually balance it when completed, flight ready. The sim crap with components calc. is just that crap. I've never done that.
I confess I am curious about this comment. I know there are a few areas where it's easy to get tripped up but "gotten nowhere" seems a bit extreme. More detail on where you hit the wall would be very useful to us. It seems to me that if you start with one of the example designs you should be about 80% of the way towards having a functional model of your own rocket, although I know you do some unconventional designs and some of those might not simulate well.I have tried OR several times and have gotten nowhere so I gave up and do my own thing. The last time I made a spread sheet was 2002.
We've had a bit of debate about this within the OR team. Let me try to shed some light on the theory of operation, which I acknowledge is a bit murky here.I don't understand the need for the second checkbox(s). It seems that if you are entering an override for the mass then by definition this automatically overrides all masses. If you don't check the second box then what are you overriding? And also when it says "all subcomponents" that isn't technically correct because it doesn't override the mass of the motor.
You wouldn't be the first!Neil_w, not looking for private classes,
To add weight to a nose cone you would typically add a "Mass Component", with the chosen mass and location. There are no overrides at all used in this case. Nowhere are you attempting to substitute your own measured value for something calculated by the program, which is expressly what overrides are for. You're adding a new component to the design, and then want to let OR do it's normal calculations.but if I add weight to the nosecone to move CG, in OR do I check override all subcomponets ? If I only want to check how overriding a single componet changes the CG, do I need to check the override all componets? This is foe a ork. file rocket, Madcow DX3 2.6". Thanks, rsbhunter
I typically model simple 3FNC designs so I find it easiest for me to search for a sim file for a kit that is somewhat similar and then modify the components to achieve my new design.I have tried OR several times and have gotten nowhere so I gave up and do my own thing. The last time I made a spread sheet was 2002.
Ok, I build (for scratch builds) the rocket using the data base of components, which lists the components mass. I don't weight each component and then override the mass that was derived from the data base for that component. That is what I meant. For kits just use available sims. For all builds to determine CG after built, I weigh, and then determine CG flight ready w/o motor. Then I override mass and CG. Just saying I don't go by what the sim has given me for the CG.Crap? LOL. The virtual build is the most powerful feature of the simulation design software. If the material databases and/or component overrides are correct (the user has full control of these), then the CG is right on the money.
I will be creating a tutorial for the OpenRocket.info website that will cover all this.Neil, thank you VERY much. Your explanation tells me more than watching a video. I honestly believe there should be a "sticky" with your explanation of the need, or lack of checking those boxes. It seems the major confusion centers around the "override all componets" function....Thank you, for taking the time to reply...rsbhunter
This is the recommended methodology. App-calculated CG is a useful tool for planning, but measuring the mass and CG of the assembled rocket should *always* be done.Just saying I don't go by what the sim has given me for the CG.
Sim files downloaded from the Internet are often distressingly inaccurate. Always double check!For kits just use available sims.
I like to imagine a dojo where you make your students sim @lakeroadster builds in 30 minutes….You wouldn't be the first!
Newbie here, and now TOTALLY confused. I posted a question about finding CG on a now completed build. MADCOW DX3 2.6. I have been told to remove engine case and load, in other words, nothing in rocket body engine wise, AND I have been told to put complete loaded engine in the rocket .With the engine in, i need to add nose cone weight, without, i don't. I have all the internals in the rocket, including Jolly Logic chute release.I would really like to get a definite answer to which way is correct? It makes a big difference between the 2 scenarios!!!! Thanks for any and all advice...rsbhunter
If you have something like a body tube, you can weigh it and override its mass without overriding fins that are attached to it.I don't understand the need for the second checkbox(s). It seems that if you are entering an override for the mass then by definition this automatically overrides all masses. If you don't check the second box then what are you overriding? And also when it says "all subcomponents" that isn't technically correct because it doesn't override the mass of the motor.
There has been discussion of making component assemblies like stages and pods always override all subcomponents. We don't do it that way because it would make the interface inconsistent.But in the example given, and the way that I've done it, the override is applied to the entire stage so doesn't that automatically apply to all of the subcomponents because the stage is the assembly? I understand how if you just override for a single component it would apply to that component, or if you do with subcomponents then it applies to the parts that are subordinate to that component, but everything is subordinate to the stage.
What launch site is that?BTW, I have a buddy that loves scratch building rockets and he has some beauties. All used the RS- CP calcs, to determine CP and never had a problem. Just a few here:
View attachment 642887View attachment 642890View attachment 642894
I understand that part of it but the analogy doesn't follow through to the override for the entire stage. The stage is not an individual component, it is only the assembly of components, so to override the mass of the stage is by definition overriding the assembly of components. I understand the desire to keep the interface the same but in the case of the stage I think it should have a different dialog box or the second checkbox should be grayed out.If you have something like a body tube, you can weigh it and override its mass without overriding fins that are attached to it.
As I explained above there *is* a function and value to overriding the mass of virtual components such as stages without the subcomponents. There's no reason to remove that capability (unless we were to render it unnecessary due to changes elsewhere).I understand that part of it but the analogy doesn't follow through to the override for the entire stage. The stage is not an individual component, it is only the assembly of components, so to override the mass of the stage is by definition overriding the assembly of components. I understand the desire to keep the interface the same but in the case of the stage I think it should have a different dialog box or the second checkbox should be grayed out.
That is the Silica launch site, just NE of Fond du Lac. 10,000 ft waiver. The problem is a schedule can't be made.. There is no access to any of the fields other than driving on them, so if wet no go. If the upcoming weekend looks favorable e-mail sent out on the Monday before and no go or go issued on Thursday, so hard for fliers to schedule. There are a few of us retired guys that fly weekdays. Also only Fall launches after crops are off, sometimes as soon as early August which looks like it this year, big field with winter wheat.What launch site is that?
Best,
Neil_w, not looking for private classes, but if I add weight to the nosecone to move CG, in OR do I check override all subcomponets ? If I only want to check how overriding a single componet changes the CG, do I need to check the override all componets? This is for a ork. file rocket, Madcow DX3 2.6". Thanks, rsbhunter
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