Cerpently
You are flying downwind in the circuit, aeroplane perfectly trimmed for straight and level say 95knts/2350rpm in a warrior, assuming there is nothing below you lower the nose to increase speed to 110 knts then reset the attitude.
Nose climbs due to increased dynamic pressue on the trim tab, now with this new found increase in altitude raise the nose to say 65knts and reset the attitude to S & L. Nose drops away as you would now expect.
Classic mistake or (back to the thread) "BadHabit" is student or novice PPl'er who from crosswind in the circuit lowers the nose at circuit height, doesn't give the airplane a chance to accelerate properly and trims for straight and level at 80knts - turns downwind and due to the aircraft accelerating in the turn increases altitude to cct hght +100
Had the privilige of checking out a retd. grp commander in the RAF who's last job was flying F3's. You'd think it would be very straightforward to sort out a PPl for somebody with such experience but he would happily admit it was actually reasonably difficult.
How did he get through it
Old RAF adage at every phase of flight "TRIM, TRIM, TRIM"
If its good enough for the RAF doing 7 miles a minute its good enough for us spam can drivers doing 1.5!
And to answer the second part of the question, on approach the speed is maintained by the elevator and the trim tab. Think of the throttle as a rate of descent/climb leve. It either gives 0fpm rate of climb/descent or a positive or negative figure. Large throttle movements will give a variation in airspeed, subtle changes in power wil not, they only modify the rate of descent sufficiently to remain on your intended glide path to the runway. This is assuming of course that you are at the right height turning finals.
I always advocate getting into the "letterbox" which is an imaginary slot at approximately 1.5 miles out at approximately 550-600 feet.
If you get into the letterbox and set the power that your instructor told you to set the first time you flew the aircraft in the circuit when you were getting checked out, then the subtle changes in power on an average day (wx wise) are tantamount to the instructor figure plus/minus 250 rpm.
This will give the the dearly sought after stable approach you can clearly see that the good approach comes from a good base leg - getting you into the letterbox....
Last edited by G-SPOTs Lost; 31st July 2002 at 22:41.