Thread: New Product Change Sun 10 blade 70mm
View Single Post
Old Oct 11, 2012, 08:14 PM
AirX is offline
Find More Posts by AirX
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,848 Posts
Originally Posted by PeterVRC View Post
I don't think THRUST is the key here.
More important is Efllux Speed and CFM. And what that pair drive your plane too.
Thrust must come from the volume and how fast it moves.
The volume is not set JUST by the area, because air is made up of molecules that can have their density (of them) altered. So more dense means more 'weight' to their force.

How does someone come up with the idea that CFM by Velocity must always be equal end result 'thrust'??? Because DENSITY of that volume can change.
In a non-compressable liquid the resultant is fixed... but not in a gas.

So I would want to be seeing maths that includes air density...not just ambient air pressure, but pressure AFTER the 'pump'.

Your an engineer arent you? There are others smarter than you and I that have defined all physics and math behind thrust force and power needed to make that happen, we arent breaking new ground. If you look up the right books fluid dynamics is right at your fingertips.
Websters defines thrust: to push or drive with force.

What changes a gas density? Temperature and altitude, since both are constant at the time of a test or the instance that the math models then they are taken a constant number in this instance.

Mass is in this instance a defined ammount of moving fluid (air) = density * velocity * area = mass flow rate or Mdot for William. The equation then becomes (density * area * velocity^2 = force) and (density * area * velocity^3 = power).

Peter are you trying to change accepted math/physics applied to fluid flow?

Eric B.
AirX is offline Find More Posts by AirX
Reply With Quote