When tip tanks are removed from wings, which statements are true?

• A. Parasite drag decreases
• B. Induced drag increases
• C. Both statements are true
• D. Neither statement is true

Answer: (B)

Tip tanks act like endplates at the wingtips, smoothing the pressure distribution and weakeningwingtip vortices. That reduces induced drag for a given lift. When you remove the tip tanks, the endplate effect disappears, the wingtip vortices strengthen, and induced drag increases. At the same time, tip tanks add external surface area and wetted area, which contribute to parasite drag. Removing them removes that extra surface, so parasite drag tends to decrease. So removing tip tanks causes induced drag to rise and parasite drag to fall, meaning both effects described are true in sum. The larger, more noticeable change is the increase in induced drag, but the parasite-drag change also follows this logic.