For some reasons, when I start launching a sequence LLT analysis of a 3D wings, the program instantly become frozen and not responding. The other analysis method like VLM1 and VLM2 is working just fine.
I have try re-downloading the program and reset all the settings and it still doesn't work.
Can you post your project file and system specification along with what windows version (including which update) you're using.
It certainly does not seem to be related to the latest version update, since I was able to run a T1 LTT analysis just fine.
Cheers,
Stefan
Last edit: Stefan 2022-12-03
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I'm using XFLR version 6.58 (the latest one).
Processor 12th Gen Intel(R) Core(TM) i7-12700H 2.30 GHz
Installed RAM 16.0 GB
System type 64-bit operating system, x64-based processor
For me the LLT iteration limit was set to 0 for some reason. Check if that also solves the problem for you (Analysis -> Advanced Settings).
Just a heads up about two things I noticed in case you don't know and/or this wasn't just an example:
Your Reynolds number (3e4) is very small. The accuracy of XFoil starts to degrade rapidly at such low Reynolds numbers, especially if the airfoils are thick and have a lot of camber. I'd recommend a thin (t < 6-7%) airfoil but it's still likely that the results will be very far off. Just keep that in mind when doing your analysis.
You also used a lot of pannels for the wing. Unless the geometry changes drastically that is generally unnecessary and just increases your calculation time of the vlm & panel method (the LLT is not influenced by the individual model density, but it's own settings.). The default x-density is usually good enough and you probably don't need to change the y-density too much.
I attached an example where I doubled & quadrupled both densities. As you can see the differences to the default density are minuscule.
For some reasons, when I start launching a sequence LLT analysis of a 3D wings, the program instantly become frozen and not responding. The other analysis method like VLM1 and VLM2 is working just fine.
I have try re-downloading the program and reset all the settings and it still doesn't work.
Last edit: Pongpat Tarinamornpong 2022-12-03
Can you post your project file and system specification along with what windows version (including which update) you're using.
It certainly does not seem to be related to the latest version update, since I was able to run a T1 LTT analysis just fine.
Cheers,
Stefan
Last edit: Stefan 2022-12-03
I'm using XFLR version 6.58 (the latest one).
Processor 12th Gen Intel(R) Core(TM) i7-12700H 2.30 GHz
Installed RAM 16.0 GB
System type 64-bit operating system, x64-based processor
For me the LLT iteration limit was set to 0 for some reason. Check if that also solves the problem for you (Analysis -> Advanced Settings).
Just a heads up about two things I noticed in case you don't know and/or this wasn't just an example:
Your Reynolds number (3e4) is very small. The accuracy of XFoil starts to degrade rapidly at such low Reynolds numbers, especially if the airfoils are thick and have a lot of camber. I'd recommend a thin (t < 6-7%) airfoil but it's still likely that the results will be very far off. Just keep that in mind when doing your analysis.
You also used a lot of pannels for the wing. Unless the geometry changes drastically that is generally unnecessary and just increases your calculation time of the vlm & panel method (the LLT is not influenced by the individual model density, but it's own settings.). The default x-density is usually good enough and you probably don't need to change the y-density too much.
I attached an example where I doubled & quadrupled both densities. As you can see the differences to the default density are minuscule.
Cheers,
Stefan
Last edit: Stefan 2022-12-04
The LLT iteration limit is the problem. Thank you for your time to help me solve this.