Learn Russian: Утром наш самолёт полетит в Китай. - Our airplane will fly to China in the morning.

In Russian, parts of the day use the Instrumental case to say when something happens. So утро (morning) becomes утром (in the morning) with no preposition needed. You will also see this with днём (in the afternoon) and вечером (in the evening).

How do we know this is future tense ("will fly") when there's no Russian word for "will"?

The verb полетит is perfective. When you conjugate a perfective verb using standard present-tense endings (like the -ит here), it automatically becomes future tense. It shows that the action will be successfully completed or started in the future.

Is the по- at the start of полетит related to the preposition по?

You are currently learning the preposition по, but here по- is a prefix attached directly to the verb лететь (to fly). Adding this prefix to a one-way verb of motion makes it perfective. For future trips, it emphasizes setting off, so самолёт полетит means the plane will take off and make its journey.

Why is it в Китай and not в Китае?