Well I can read the reason why my question was put on hold
" ask about a specific physics concept and show some effort"
However I wonder if that would be the good action for questions like these. I honestly did a lot already, however everything I always saw was just "beating around the point". And I knew I missed a simple fact from the text in the question.
A comment already gave the answer (as I showed), which was simply that if the thrust to weight is constant, the accelleration is also constant.
I did no realise this, and without this one can't beat the question. I started the question thus with "I have no idea how to start this...", simply because I saw that in whatever I would do I would miss a value - and any extra information would determine which method to use.
So this question could both be answered easily as well as helps understanding. I could point all things I did already, and then you would all look into a mistake in my calculations or something. But I knew that wasn't the problem (and thus a waste of everyone's time) and I knew the problem was misinterpreting the problem.
Is closing really good for actual questions about "understanding information given"?