Terminated Flight Question

[syazoo]

Can anyone tell me how to calculate how far a drone will travel in a liniar direction if the flight is terminated. Banging my head on the math and trying to find a formula. Thank you!!

Edit: Found it.

 

[Donnie Frank]

Can anyone tell me how to calculate how far a drone will travel in a liniar direction if the flight is terminated. Banging my head on the math and trying to find a formula. Thank you!!

Edit: Found it.

Easy. A normally-functioning drone will stop at the point of termination.

D

 

[syazoo]

Easy. A normally-functioning drone will stop at the point of termination.

D

I could have worded this a little better…. I was wondering about the x axis length of the parabola the drone takes to the earth after a termination is executed.

 

[Donnie Frank]

I could have worded this a little better…. I was wondering about the x axis length of the parabola the drone takes to the earth after a termination is executed.

Too many missing variables to answer this. What is your velocity along the X-axis at the time of termination??? What do you mean by "terminate?" Is the drone functioning normally? Are you in ATTI mode? By "terminate" do you mean kill the motors??? Kill the mission? Of course all of this is going to be effected by the drag coefficient of the drone AND your air density.

It's an interesting question. I'm not sure why you would ask this question, but answering it accurately without all those missing variables is going to be impossible. Even worse, some of the variables are dynamic, further making it impossible to answer with any kind of consistency or accuracy.

D

 

[syazoo]

Too many missing variables to answer this. What is your velocity along the X-axis at the time of termination??? What do you mean by "terminate?" Is the drone functioning normally? Are you in ATTI mode? By "terminate" do you mean kill the motors??? Kill the mission? Of course all of this is going to be effected by the drag coefficient of the drone AND your air density.

It's an interesting question. I'm not sure why you would ask this question, but answering it accurately without all those missing variables is going to be impossible. Even worse, some of the variables are dynamic, further making it impossible to answer with any kind of consistency or accuracy.

D

You are exactly right, all of the variables are required for the calculation of the linear distance . So it was just a formula that I was looking for. The variables I have.
Once I have the formula I just change variables for flight characteristics right….
I was a little surprised when I was first asked to provide the information. Here in Canada our regulations mention termination of the flight in the case of last resort if a flight becomes uncontrollable and if you are able to terminate. So if you were to submit a request for an SFOC, for example, you would be expected to be able to answer that question based on the flight plan you submit. They ask based on max speed and altitude of the flight plan. So the calculations are only correct for that scenario. I can understand that perhaps the authorities are of the belief that the pilot knowing the information has a little extra headroom in the case of safety. Either way, I found it interesting. I found the formula and an online calculator with a Google search of projectile motion calculator.

 

[Donnie Frank]

You are exactly right, all of the variables are required for the calculation of the linear distance . So it was just a formula that I was looking for. The variables I have.

Well then I'm sure you're aware that even the formula is going to change based on weight and drag, which is contingent on the shape of the drone and air density. Because the drone will probably be rotating over all 3 axis, even its drag coefficient will be inconsistent. I'm sure the variance is negligible for your purposes, but definitely worth considering.

Once I have the formula I just change variables for flight characteristics right….

Do you know the drag coefficient of your drone??? The weight is easy enough to determine, but even the drone brand and make isn't specified - which makes knowing the drag coefficient even more varied.

I was a little surprised when I was first asked to provide the information. Here in Canada our regulations mention termination of the flight in the case of last resort if a flight becomes uncontrollable and if you are able to terminate. So if you were to submit a request for an SFOC, for example, you would be expected to be able to answer that question based on the flight plan you submit.

Interesting. Do they specify what they mean be "terminate???"

The easiest way to answer this question is fly full force in ATTI mode, let go of the joysticks and then record how far the drone "coasts." Do two passes in opposite directions and average the results. This will sort of compensate for wind speed, which you should know before starting the tests. Naturally, if wind is 5mph, that pass should end @ 5mph since the drone will obviously "coast" on its own without ever stopping.

I would say gathering, recording and extrapolating data in this manner will get you in the ballpark - 90% accurate by my estimate.

They ask based on max speed and altitude of the flight plan. So the calculations are only correct for that scenario.

Correct. You could certainly collect an entire set of data using ATTI mode at varying speeds. Say 10-40 mph in 10mph increments. At least this way you could answer their question plus or minus 10%.

I can understand that perhaps the authorities are of the belief that the pilot knowing the information has a little extra headroom in the case of safety. Either way, I found it interesting. I found the formula and an online calculator with a Google search of projectile motion calculator.

I like my ATTI mode idea better, which takes individual drone drag coefficient into account to achieve a "real world" estimate.

D

 

[syazoo]

I thought of mass and drag, Temperature, Wind and even wondered what Other forces that I don’t even know about would affect this parabola. Then it occurred to me that the question was being asked on a questionnaire that covered any UAV. And that the question only asked At max plan altitude and speed. At that same time it occurred to me there was no realistic way to have an expectation of exact accuracy and they are satisfied with one sample. I am satisfied with the results of the trajectory calculator results. For example the trajectory calculator return to result for input of initial velocity of 30 km an hour at an altitude of 120m travelling only 41m before hitting the ground. I had sent the Problem to a fellow who I know which I am quite certain would not make an error in the math. His calculation was 40.2 m. I did ask him about drag. His response was it’s not going affect the result much. I wonder if the drone trying to maintain altitude in atti would affect the test.