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turkkusuroket

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Hi everyone. I build a rocket in Open Rocket. I have a problem when run simulation. I uptaded .org file and a picture that shown error message.

What is the solution of the error?

Thanks
 

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dhbarr

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It's saying your chute is ejecting too early or too late. Edit your motor delay from "0" to "None".
 

SeanW78

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I copied your motor configuration and changed the delay from "0" to "None" and it sim'd fine.
upload_2020-1-10_7-33-12.png


I think the message you were getting may have been from the 2nd deployment.
 

Eric

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You could also have to small of a drogue shoot selected. I get that if the main comes out when the drogue is letting it fall faster then 65fps. I mostly disregard the error code. My drogue is supposed to descend at 75fps and my main can handle that opening speed.
 

turkkusuroket

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Hi everyone. I build a rocket in Open Rocket. I have a problem when run simulation. I uptaded .org file and a picture that shown error message.

What is the solution of the error?

Thanks
 

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turkkusuroket

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No, simply changed the delay to none on the motor. I've attached the updated .ork
We have to adjust the launch rod angle in 5 degrees. Already an error occurs when i make this setting. Im sending e picture for this adjustment
. Thank you :(
 

SeanW78

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Hmm, now that error occurs on mine as well.
 

GalantVR41062

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10 m/s is 22.3mph, could the wind speed being so high on the ground cause issues, weather cock and a very horizontal flight and add velocity at drogue deployment?

~John
 

neil_w

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10 m/s is 22.3mph, could the wind speed being so high on the ground cause issues, weather cock and a very horizontal flight and add velocity at drogue deployment?
Lateral velocity is the issue when the rod is angled:
upload_2020-1-10_11-33-19.png
 

turkkusuroket

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neil_w

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We have to adjust rod angle in 5degrees. Isn't any way for the problem? I work the problem for 2 weeks :(
First of all, I do not believe there's any weathercocking here; speed off the rod is extremely high.

Let's look at some numbers.

According to the sim, maximum vertical velocity of rocket = ~1100 fps at motor burnout

Assuming 5 degree flight angle, we can predict lateral velocity from a basic trig calculation: maximum lateral velocity = 11000 * tan(5 degrees) = 96 fps

The sim says:
upload_2020-1-10_12-29-18.png

That shows about 140 fps maximum lateral velocity. Why the difference? My suspicion is wind. The sim is set for ~5 mph wind. I believe that the rod at +5 degrees is with the wind, which means the wind is adding to the lateral velocity over the course of the flight.

So I tried changing the rod angle to -5 degrees, and look what happens:
upload_2020-1-10_12-30-20.png


Maximum lateral velocity is now down to about 84 fps, and deployment is around 47 fps (and the warning goes away).

What do we learn?
1) Launching the rocket at an angle ensures that it will have some lateral velocity at apogee.
2) Launching into the wind will offset that somewhat, provided that the rocket does not weathercock (again, if you use the very long long rail and high-thrust motor you have in the sim then weathercocking should not be an issue)
3) Your parachute at apogee needs to be able to handle it. Build accordingly.
 
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