Planes with propellers have their advantages

Q: Why are the hurricanehunter planes only twin turboprops and not the fan jets that passenger planes use?

— Edward Zell, Ohio

A: The turboprops are more tolerant of hail than the jets. Airplanes that penetrate thunderstorms have an increased chance of encountering hail. Additionally, the two types of airplanes used, the P-3 and the C-130, are especially rugged.

Q: How does a propeller engine slow the plane for landing ?

— M. Pengilly, Ohio

A: The propeller is rotated so that the prop wash (thrust) is directed forward. There are two advantages for the propeller aircraft. When the propeller is flattened out from the flight idle position, it creates a large amount of drag. Further rotating the propeller blades reaches a point where the airflow actually is opposite the direction of travel.

Propeller airplanes can land on short runways due, in part, of the effectiveness of the propeller reversing.

Q: Is it normal for small regional turboprops to shake a lot just before and during takeoff ?

— Josh, Peoria, Ill.

A: Some turboprop aircraft change the speed of the engines for flight and use varying pitch of the propeller, causing some vibration on the ground or just prior to landing. It depends on the type of airplane and the conditions.

Q: Why do winged airplanes use engines with twin propellers spinning in opposite directions?

— James R. Gammage, Sharpsburg, Ga.

A: This increases control during flight with one engine inoperative. Propeller discs (a spinning propeller acts as a disc) produce thrust asymmetrically due to aerodynamics, and by keeping the most efficient part of the disc closer to the center line of the airplane, control is enhanced.