The idea sounds very good, but please demonstrate with a few images in the description to show what it looks like.
As an image for the mod, I would also suggest a firing capsule launcher.

I recommend to check raspberrypuppies mod list, he made many turret art that you can set as dependency... the only issue is he didn't update all his mods to 2.0 yet.

https://mods.factorio.com/user/raspberrypuppies

Great idea!
(The mortar turret looks good as a capsule launcher.)

Tanks for the feedback ! You're right, I totally overlooked the gallery, and I will add some images as soon as I have better graphics. And thank you as well for the art suggestion. However, this is my first mod, and I still have to learn how to change graphics, so it might take a while before I get it working.