OpenRocket: How do you change the ejection time?

[MetricRocketeer]

Hi everyone,

I am just learning OpenRocket. I am trying to run simulations. I would like to change the ejection delay for a motor, but I don't understand how to do that.

Could someone please tell me what to do.

Thank you .

Stanley

 

[Nytrunner]

In the motor selection window, there is a drop-down for the delay length towards the top (over the list of motors).

You can either select the preset delays or enter a value yourself

Example:
-For a C6, the 3, 5, and 7 delay options are selectable.
-For an H120, (an adjustable delay) you can enter any integer value you want up to the max delay (14 I think)?

 

[MetricRocketeer]

Hi Nytrunner,

Right. Thank you. I should have seen that.

Stanley

 

[neil_w]

Right. Thank you. I should have seen that.

Don't worry, you're not the first one that didn't.

 

[MetricRocketeer]

Thank you, neil_w.

Incidentally, I always chuckle at your description of "marginally stable."

 

[neil_w]

Thank you, neil_w.

Incidentally, I always chuckle at your description of "marginally stable."

https://www.rocketryforum.com/threads/for-the-python-fans.156533/post-1944579

 

[afadeev]

In the motor selection window, there is a drop-down for the delay length towards the top (over the list of motors).

You can either select the preset delays or enter a value yourself

Example:
-For a C6, the 3, 5, and 7 delay options are selectable.
-For an H120, (an adjustable delay) you can enter any integer value you want up to the max delay (14 I think)?

The above definitely works.

However, what I find to be even more efficient, is to go to <Recovery> tab and Select Deployment to Apogee:


Then you select your potential motors, run the simulation and observe "optimum delay" values for a given motor.
That, in turn, allows you to go through your motor stash, and select the motor with delay length closest to optimum. Or order a motor with the right delay, if you don't have one in stock.

This is also a good time to go and re-evaluate whether your "potential" motor selections are actually sensible, and discard those with too slow velocity off the rod:



HTH,
a

 

[Nytrunner]

However, what I find to be even more efficient, is to go to <Recovery> tab a

I'm not gonna lie, I don't think I've ever clicked on the recovery configuration tab

Similar to what you mentioned above, for high power I always set my drogue (or chute for single deploy) to apogee when I place the component itself, so I've never had the inkling to even explore that tab!

Thew more you learn

 

[MetricRocketeer]

Hi Nytrunner,

I am getting a little confused. What method do you use?

Stanley

 

[Nytrunner]

Hi Nytrunner,

I am getting a little confused. What method do you use?

Stanley

Instead of relying on selecting the proper motor delay, I just set the paracjute component to "deploy at apogee" so that the sim can run fully

The simulation results show optimum delay, so I use that to select/adjust motor delay for my flight

 

[MetricRocketeer]

Instead of relying on selecting the proper motor delay, I just set the paracjute component to "deploy at apogee" so that the sim can run fully

The simulation results show optimum delay, so I use that to select/adjust motor delay for my flight

OK. Now I understand. Thank you.

 

[Lt72884]

resurrecting an old thread. Im not sure if this is a bug or not but for the L2200G in openrocket, i can not set a specific time. I highlight the time, backspace to remove the numbers, type in the number i want, hit enter and it does not save it. I have tried to hit ok, enter, and it will not save it. The only numbers i can choose is 0,6,12,and 18.

driving me crazy haha

 

[jmasterj]

resurrecting an old thread. Im not sure if this is a bug or not but for the L2200G in openrocket, i can not set a specific time. I highlight the time, backspace to remove the numbers, type in the number i want, hit enter and it does not save it. I have tried to hit ok, enter, and it will not save it. The only numbers i can choose is 0,6,12,and 18.

driving me crazy haha

There's no motor eject for L motors and up.

 

[Voyager1]

There's no motor eject for L motors and up.

Correct!
If there are no motor delays entered into the motor file, then no delays will appear in the drop-down list, and you won’t be able to enter one. Typically, Ls and up don’t use delay charges and only rely on electronic deployment.

 

[Lt72884]

Correct!
If there are no motor delays entered into the motor file, then no delays will appear in the drop-down list, and you won’t be able to enter one. Typically, Ls and up don’t use delay charges and only rely on electronic deployment.

ok, that makes some sense. But what doesnt make sense is why are there numbers in the drop down list for delays then?

Second, how should i setup open rocket to test simulations with an L motor and not use a delay time? since the only option for me in the drop down is either, 0,4,8,12,18. I could type none, but does that give me accurate sim data?
How do i tell OR that im using electronics so that OR can find my correct apogee?

thanks

 

[Steve Shannon]

ok, that makes some sense. But what doesnt make sense is why are there numbers in the drop down list for delays then?

Second, how should i setup open rocket to test simulations with an L motor and not use a delay time? since the only option for me in the drop down is either, 0,4,8,12,18. I could type none, but does that give me accurate sim data?
How do i tell OR that im using electronics so that OR can find my correct apogee?

thanks

Look at post 10. Set your parachute to open at apogee.

 

[Lt72884]

Look at post 10. Set your parachute to open at apogee.

ok, i will try that out. Thanks. I was searching on google and i think for the L2200, its a small bug where it lists delay times for that motor and wont let the user type in the value they want. I wanted 22.2 seconds but OR was not letting me do so haha.

 

[Lt72884]

Look at post 10. Set your parachute to open at apogee.

yeah its not calculating the correct time even with the parachute set to apogee. It defaults back 18 seconds. If i type none in the box and hit ok, it does not save it, it defaults back to 18 or 0

 

[neil_w]

It doesn’t matter what the motor delay is if the parachute is set to deploy at Apogee. The motor ejection event is ignored.

 

[Lt72884]

It doesn’t matter what the motor delay is if the parachute is set to deploy at Apogee. The motor ejection event is ignored.

thats good to know. then there is something else going on. if i open the exact same file on my laptop, i get an extra 600 feet of altitude. on the desktop, i get 9515 and on laptop, its 10,075



i have not changed anything on the file except the chute opens at apogee. To test, i switched the times for delay on the motor, and it does not keep the altitude. it re-calculates it every time regardless of the parachute set to opening at apogee.


thanks

 

[neil_w]

Any reason you're not using the new version of OR?

 

[Lt72884]

Any reason you're not using the new version of OR?

no just have not updated yet. what gives it away im not on newest haha?
however, both laptop and desktop use same version, but both act way different

 

[neil_w]

I only ask because it's not easy for me to debug 15.03 issues anymore. If you upgrade to the latest (well worth it) then it'll be easier to help. Or maybe the problem will go away.

There are differences in the GUI that are the giveaway.

 

[neil_w]

no just have not updated yet. what gives it away im not on newest haha?
however, both laptop and desktop use same version, but both act way different

Have you looked at the actual simulation outputs (on the Simulation tab) or just the numbers in the lower left corner of the rocket figure? The numbers in the lower left corner might be subject to differences in the default sim settings on the two machines. The outputs of the sim should be consistent, if the sim settings are the same.

 

[H. Craig Miller]

The other needed screenshot from each simulation is the launch conditions.



If these are not identical, the results will not be consistent.

 

[Handeman]

I would highly recommend you get rid of the Discontinuity in rocket body diameter warning. Just make sure your nose cone and all BT ODs are the same and you don't have a gap between any BTs. That should also help get you more consistent sims.

 

[Lt72884]

I only ask because it's not easy for me to debug 15.03 issues anymore. If you upgrade to the latest (well worth it) then it'll be easier to help. Or maybe the problem will go away.

There are differences in the GUI that are the giveaway.

ok, with the update, same issue. If i have the parachute set to deploy at apogee, it does not override the ejection charge time. The altitude is the same in the flight sim, the plotted data, and bottom left corner. If i set the time to 0, i get an altitude of 1300 feet, even with "deploy at apogee" set. if i change the time to 6 seconds, it changes the altitude to about 6000 feet. so its not overriding the ejection time nor will it let me type in a value and keep it, or set it to none

 

[neil_w]

You have a drogue parachute deploying at ejection. The quickest way to see such things is on the Recovery subtab under "Motors and Configuration":


For dual deploy, you typically want to have the drogue set to apogee, and then the main set to deploy at a specific altitude.

 

[Lt72884]

You have a drogue parachute deploying at ejection. The quickest way to see such things is on the Recovery subtab under "Motors and Configuration":
View attachment 568312

For dual deploy, you typically want to have the drogue set to apogee, and then the main set to deploy at a specific altitude.

i keep forgetting about that drouge shoot. I know it exists, i just forgot about it. I was thinking about the drouge, then father in law said "you wanna come over for hamburgers" and it was game over at that point haha

let me set that to apogee as well and see what happens

 

[JoePfeiffer]

What I'm most curious about is why those thrust curves show any delay at all for an L2200. Going on thrustcurve.org the metadata shows the motor as plugged (which is correct), while both thrust curves for it, uploaded by different people, show those delays.

(15.03 took motor delays from the thrust curves, while 22.02 takes it from the metadata. I don't know which is generally more accurate, but in this case the metadata is correct. The next version will allow the user to enter any value they want in addition to the manufacturer-supplied delays, to accomodate things like delay adjustments and electronic timers similar to the AT Electronic Front Closure).