Why is airspeed different in climbs and descents although the AoA doesn't change? Here are the background facts:
This excercise has the objective to familiarise the student with the slow flight characteristics.
The steps are:
1)Establish straight and level, 90% RPM, 15 units AoA, hands out trimmed. (No specific airspeed, it just happens to be appr. 110 KIAS)

Add 5% RPM (so i set it at 95%) and establish a climb with 15 units AoA for 500 ft climb. No bank, whatsoever. (Again no specific airspeed, it just happens to be appr. 100-105 KIAS)

Reduce 5% RPM so you fly straight and level at the new altitude (Same parameters as step 1)

Reduce 5 % RPM (so i set it at 85%) and establish a descent with 15 units AoA for return to the initial altitude. No bank whatsoever. (No specific aispeed during the descent, it just happens to be appr. 115-120 KIAS).


My question is simple. Why is the airspeed different? The answer might be simple. I simply can't figure it out.
Hope i clarified it as much as possible.
You should see the same airspeed for the same AOA and non-accelerated flight with a mild climb or descent.

Except with a Buckeye?

The Buckeye has its thrustline low enough so that at different power settings you have different pitch trim settings. Add power to climb and the thrust pitches the nose up. You now have to trim nose down. Nose down trim means less down force on the tail, which means less lift required by the wing, which means a slower speed for the same AOA.

Conversely, pull power off and the nose wants to drop, leading to nose up trim, more down force on the tail, more lift required by the wing, higher IAS for the same AOA.

I frankly never noticed this effect, and never taught it. Wish I could go back and check it out!