PPRuNe Forums - View Single Post - The F-35 thread, Mk II
View Single Post
Old 6th Mar 2020, 15:35
  #27 (permalink)  
beardy
 
Join Date: Nov 2000
Location: UK
Age: 69
Posts: 1,405
Received 40 Likes on 22 Posts
Originally Posted by ShyTorque
Yes, precisely. So the way to descend is to reduce power. From what Beardy wrote, it appears he thinks differently.
Not at all. I refer to the horizontal frame of reference, not the aircraft, which changes with pitch. When you decrease the power a speed stable aircraft will descend in order to maintain its speed. The initial part of the descent is an acceleration in the vertical plane until a new stable equilibrium is achieved and then the RoD will be constant. The aircraft frame of reference may or may not pitch, swept wings and blown wings tend not to pitch, just sink in the same attitude.
At a constant rate of descent (vertical speed) the vertical component of lift equals weight.
I refer you to Newton's first and second laws of motion. They've been around for a while and are close enough to true to be used in aerodynamics.


Interestingly current CFS basic teaching is not that power controls descent, but that pitch does. ie Point at the numbers and control speed with power. It wasn't always thus (the teaching.)

Last edited by beardy; 6th Mar 2020 at 16:08.
beardy is online now  
The following users liked this post: