How does density altitude affect climb rate?

How does density altitude affect climb rate?

• A. Decreases climb rate.
• B. Increases climb rate.
• C. No effect on climb rate.
• D. Only affects engine temperatures.

Answer: (A)

Density altitude is the altitude at which the air density would be in the standard atmosphere; when density altitude is higher, the air is thinner. In thinner air, engine power and propeller efficiency drop, wing lift is reduced for the same speed, and drag behaves differently. Since climb rate depends on the excess power available (power available minus power required), the reduction in power and lift—and the relative increase in drag—means less surplus power to climb, so the rate of climb decreases. In hot, high conditions you’ll notice a noticeably slower climb than in cool, dense air. It isn’t a matter of only engine temperatures, and it doesn’t increase or stay the same.

Density altitude is the altitude at which the air density would be in the standard atmosphere; when density altitude is higher, the air is thinner. In thinner air, engine power and propeller efficiency drop, wing lift is reduced for the same speed, and drag behaves differently. Since climb rate depends on the excess power available (power available minus power required), the reduction in power and lift—and the relative increase in drag—means less surplus power to climb, so the rate of climb decreases. In hot, high conditions you’ll notice a noticeably slower climb than in cool, dense air. It isn’t a matter of only engine temperatures, and it doesn’t increase or stay the same.