Originally Posted by james ozzie
Sorry CJ but I don't buy your maths. Methinks thou does't confuse a moving and static frame of reference (or something).
Sorry James, it's not my maths. The basic formula is already in post #2 (by
renard). Otherwise Google is your friend, there's quite a lot about the subject on the the web, and clearer than I could write it.
The trouble starts when you begin describing it in words... everybody has his own way for "getting one's mind around it". After that, some find a moving reference frame easier, others a static one. The end result is the same.
Big fans (much like props) accelerate a lot of air a little, but they still accelerte it.
CJ