"long time needed" is a correct and usable phrase in written English.
For example, you could use the phrase in a sentence like, "This project will require a long time needed for completion."
My father had for the first time in a long time, needed a cuppa.
A fixed mesh was used, with spacing varied to accomodate the deep thermal diffusion during the long time needed for mass diffusion.
However, the drawback is the long time needed to assess the hydraulic performance, whereas the engineers require simple and rapid characterization parameters to design the hydraulic barrier.
It is these new subs that parliament will be voting on this year, theoretically because of the long time needed for design and construction.
How should officials resolve the conflict between the deadline for submitting returns one week after the election and the long time needed to for a manual count?
Estimating thermal properties for thick or solid foods at temperatures greater than 100 °C is challenging for two reasons: the long time needed to reach a constant temperature, and the pressure needed to be maintained in the sealed container.
Everybody moving into Texas, and even people who have been living here a long time, needs to be educated about education in this state.
It is proposed that nonlinear growth in blends containing a low-molecular weight amorphous polymer (large diffusion coefficient) is, in some cases, due to the long times needed for a steady state to be reached and not a diffusion-limiting process.
RFID applications such as monitoring an object for a long time need to identify tags repeatedly within the scope of the reader.
In fact, once the cognitive planning tool finalizes optimizing the network, only changes to the network environment that last a long time need to be communicated.
The disadvantage is a long calculation time needed to evaluate the monodromy matrix and instability zones.
