PPRuNe Forums - View Single Post - Piston vs Jet
Thread: Piston vs Jet
View Single Post
Old 7th Jul 2004, 01:40
  #10 (permalink)  
ITCZ
 
Join Date: Jan 2001
Location: Australia
Posts: 725
Likes: 0
Received 0 Likes on 0 Posts
Both methods work 'okay' in a GA type.

The 'stick for aimpont, thrust for speed' is almost exclusively the recommended method in a jet transport flying a final approach.

The jet has very STRONG primary effects of control, and WEAKER secondary effects of control.

If you see your aimpoint 'rising' in your windscreen, then you pull back on the stick. STRONG primary effect of increasing angle of attack is MORE LIFT, which will put your aimpoint back where you want it quickly.

The weaker secondary effect of increasing angle of attack is to wash off speed. So you add thrust. Strong primary effect, increase speed. Very weak to negligible secondary effect is to increase lift (the 'vee' in the 'half rho vee squared' part of the lift equation).

So flying finals with 'stick for aimpoint, thrust for speed' is far better in effecting the changes you want to your glidepath and speed, when the aircraft you are flying has strong primary effects of those controls with weak secondary effects.

(With 3,000hr in bush pistons in my dim dark past, i agree with the GA lads/lasses who advocate the reverse for light pistons. Very effective for short fielders. But most people who are being ab initio'ed these days are given one method that works reasonably well for pistons and best for the larger types they aspire to.)
ITCZ is offline