Ask the Captain: Questions that impressed our pilot columnist

Question: Terrific column and much-appreciated perspective. I have two questions about engines: On a two-engine jet, do the engines rotate in opposite directions to avoid any torque? And sometimes while at the gate, the main fan of a jet engine appears to be or is rotating slowly in the opposite direction of its normal rotation. Is this to move air through the cowling? 

– William Markey, Chicago

Answer: Glad you like the column. I enjoy answering the wide variety of questions. No, the engines turn in the same direction. This reduces the number of spare engines required. Unlike engines with propellers, the torque of a jet is very small (you do not notice it).

Yes, when you see an engine slowly turning at the gate there is airflow (wind) causing the rotation. If the wind is front to back the engine turns the its normal direction. If the wind is back to front, then the engine will rotate in the opposite direction.

Most of today’s modern jets have a large fan and a small core. Most of the air flows through the fan cowling so the answer to your question is yes.

Good question.

Q: As a prospective future pilot, I was wondering your thoughts on obtaining a BS Degree in piloting thru a university like Purdue or OSU versus obtaining your certifications through a school like ATP? I understand the importance of a college education, but the financial implications of a university flight school are much more difficult to stomach (especially in today’s higher education system).                   

– Joshua Ryan, Indianapolis

A: You ask a good question. The university programs are usually more structured and inclusive of courses such as aerodynamics, meteorology, physics and math. That is a significant advantage, but the cost for the student is higher.

If the cost of the flight program is out of reach, you can take the same courses while you complete your degree, then do the flying. In either, picking a high quality training facility is very important. The skills you learn in flight school are the foundation for being a successful professional pilot. 

Q: Since the DC-10 and L-1011 were so similar in appearance and capacity other than the No. 2 engine, did the DC-10’s straight duct have a slight advantage in performance and fuel consumption over the L-1011’s S-shaped duct?        

– Tom H., Canton, Texas

A: You have asked a very good question. I have not heard it asked before. Usually S ducts have a slight performance degradation due to additional drag in the duct. I would think the L-1011 did, too. However, the performance of the two airplanes were similar.

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