RockSim Errors - HELP

[Anna Tiberi]

Hi there! I am using RockSim (free trial) and it says that it does not leave the launch pad. Any ideas?

 

[Rex R]

check that all of the rocket parts have a non-zero mass.
Rex

 

[Anna Tiberi]

check that all of the rocket parts have a non-zero mass.
Rex

Hi Rex! I did that already and it still says it doesn't leave the launch pad.

 

[Rex R]

I am reasonably sure that some Rocksim ninja will be along shortly to help you sort it out. that was the extant of my RockSim knowledge(I use openRocket). anywho...welcome to the forum.
Rex

 

[Anna Tiberi]

I am reasonably sure that some Rocksim ninja will be along shortly to help you sort it out. that was the extant of my RockSim knowledge(I use openRocket). anywho...welcome to the forum.
Rex

Thank you so much!

 

[Anna Tiberi]

Any RockSim ninjas would be greatly appreciated.

 

[Woody's Workshop]

I looked at your file you posted and did a component view.
I didn't see a launch lug.
Might try that.

 

[Anna Tiberi]

I looked at your file you posted and did a component view.
I didn't see a launch lug.
Might try that.

Hello! I am new to the model rocketry modeling world. Where would I put the launch lug?

 

[Anna Tiberi]

I looked at your file you posted and did a component view.
I didn't see a launch lug.
Might try that.

Would something like this work?

 

[Anna Tiberi]

I looked at your file you posted and did a component view.
I didn't see a launch lug.
Might try that.

It still says it didn't leave the launch pad

 

[aerostadt]

The model strikes me as strange and/or difficult to work with. I am wondering if it won't launch, because it is "unstable". I tried mass override and added mass to parts and the weight of the model is unaffected (very strange). Even with the largest J-motor that will fit the stability is affected some, but not enough to make the model stable.

 

[aerostadt]

You could contact Tim Milligan at Apogee for help. Did you write this model or acquire it from somewhere?

 

[rcktnut]

I took a quick look at your design, ran out of time, have to go but found 2 components already with 0 mass. Those are: components -rocket and rocket mount. No mass for them. I added mass, loaded a motor and still no flight. Check/ edit all your components and make sure they have an amount of mass for them. I'll look over it later when I have time, you have lots of components to check. Also don't understand what motor you put in that by the description in the simulation. Good luck!

 

[Anna Tiberi]

You could contact Tim Milligan at Apogee for help. Did you write this model or acquire it from somewhere?

I wrote this model. I will try to contact him thank you!

 

[Anna Tiberi]

The model strikes me as strange and/or difficult to work with. I am wondering if it won't launch, because it is "unstable". I tried mass override and added mass to parts and the weight of the model is unaffected (very strange). Even with the largest J-motor that will fit the stability is affected some, but not enough to make the model stable.

Yes it is very complicated - unfortunately I am part of a team and not part of aircraft design. I managed to complify it and run it in OpenRocket.

 

[Anna Tiberi]

I took a quick look at your design, ran out of time, have to go but found 2 components already with 0 mass. Those are: components -rocket and rocket mount. No mass for them. I added mass, loaded a motor and still no flight. Check/ edit all your components and make sure they have an amount of mass for them. I'll look over it later when I have time, you have lots of components to check. Also don't understand what motor you put in that by the description in the simulation. Good luck!

Thank you! I must have missed those - I will continue to look through it.

 

[Titan II]

Also don't understand what motor you put in that by the description in the simulation.

CTI I55 Mellow

 

[rcktnut]

Spent some more time on your design. All of your pods left/right wing etc. had 0 mass to them. I made each one 2 oz. made sure every other component had mass still no flight. I added weight ( a lot) in your nose cone to make it stable still no flight. I found one thing goofy don't know if that is the problem or not though. Your tiny nose cone on the glider and power pod/ motor mount part are somehow interconnected. If you delete the tiny nose cone on the glider the power pod goes with it,everything nosecone body tube, chute,launch lug, everything. Don't know what else to say!

 

[kevindcornwell]

Hi there! I am using RockSim (free trial) and it says that it does not leave the launch pad. Any ideas?

Anna, I love this design! Just love it. As for the design file, there are numerous problems that must be corrected before you should expect valid simulation results.

1) Your choice of materials is a bit diverse. Carbon, fiberglass, plastics, and balsa. Not that you can't or shouldn't do that, but you've set up a design that is incredibly and unnecessarily heavy (nearly 2kg) because of inconsistent material choices and associated weights (which in some cases don't appear to make sense.)
2) Along with #1, the thickness' of materials is a bit unpredictable. 1/2" thick wings is way, way overkill. If you feel that balsa is absolutely necessary for the indicated wingspan, then I would strongly suggest you rethink the engineering on the wings. 1/2" balsa is a sledgehammer when a ball-peen is all that's needed. I would consider CF for the wings, or 3/32" Ply. Or even 1/16" balsa covered with paper.
3) I'm not convinced that a 40-odd inch wingspan can withstand the rigors of 38mm motor flights. I grant that may be why you choose 1/2" balsa (or perhaps you're going to sand it into an aerodynamic shape.) If that is indeed the case, your weight for the wing is massive. I would suggest that you actually weigh a 1/2" piece and extrapolate for the entire wing. Right now, it looks very, very suspect. Are you using 38mm motors to overcome the weight of the craft? If so, I'd encourage you to reduce the weight and use long-burn low-thrust motors (Apogee makes some very nice ones as does Aerotech. Others too I'm sure.
4) You have mass overrides on some pieces and not on others. In addition, the CG component of the mass overrides are nearly all zero. That won't do. At least guess the CG of the component as being 1/2 the distance of the overall length.
5) In most cases (in my experience) shoulders of nose cones and transitions need to be non-zero. Most of yours are zero. If that is what is causing the hang-up, then just changing them to .001 will solve the non-launch problem.
6) You used the power series shape for the tiny nosecone. I've found that that shape can be a non-starter. Just choose some other shape and be realistic about the CG.
7) A common problem is that one chooses a material that is somehow goofy in RS. I don't know why, but there have been times when I'm designing and I get a non-flight result. If I change either the material of one part (something I've customized) or exchange the part to another similar part in the database (then customize it to the same parameters as the offending part) that will fix the non-launch problem. Not all of the database entries work (typos or what, I don't know.)
8) Lastly, when I've had a non-launch result even after ensuring everything is entered just right, I have found that re-entering all the parts in a brand new file will solve the problem. Files sometimes get their britches in a hitch and you just have to start over.

Bottom line, I believe your difficulties are multiple, not a single point. Make your design consistent with part selection and parameters carefully thought-out and I think you'll solve your problem. You're using RockSim and its wonderful feature set quite well. I'm impressed with all the pod uses etc. I think you'll find that with a careful materials list, you won't be nearly as heavy and won't need nearly the lifting force as currently reflected. I think I read that you got it to work in OR. That may be, however, I've found on complex designs such as this, RS will provide greater simulation accuracy once you've got everything entered correctly. In other words, I've found that RS was a better predictor of reality. Wished it worked for other things in life...

I'd be happy to look at the file again once you've made corrections if it continues to not work.
Have fun,
Kevin

 

[kevindcornwell]

The model strikes me as strange and/or difficult to work with. I am wondering if it won't launch, because it is "unstable". I tried mass override and added mass to parts and the weight of the model is unaffected (very strange). Even with the largest J-motor that will fit the stability is affected some, but not enough to make the model stable.

Anna, you've set your mass override for the entire design to being ON (checked in the main Mass override tab) which is why Aerostadt couldn't get anything to change. Uncheck that before doing anything else.

 

[kevindcornwell]

Hi there! I am using RockSim (free trial) and it says that it does not leave the launch pad. Any ideas?

I've been staring at the design trying to figure out how to make it work. One idea would be to use carbon fiber tubes as the leading edges of your wings, all the way out. That may provide the stiffness you need to sustain the forces of rocket flight and the light-weight component needed for gliding flight. That way you could dispense with the heavy balsa wings and make them much thinner. Just a thought. I've not built any gliders but I know there are others lurking here that have invaluable experience in how to make this work.
Later (again), ;-)
Kevin