Dear Captain Lim,
I attended my second attempt for the SIA cadet pilot interview recently but ended unsuccessfully. I was asked this question:-
"Name me a World War II aircraft which is still in service today but slowly phasing out?"
The Captain gave me a hint that it is DC-- and I did come across DC-10 and gave that as the answer. However, as I did not read up on it, I couldn*t give information on it when asked to describe it.
Was my answer to the question correct, i.e. DC-10? Seems like I was wrong as when I did a search, the aircraft was only in production in 1968 that is way after WWII. Perhaps the Captain was giving me a chance to tell him what I know about an alternative aircraft (?)
With regards to Bernoulli theorem, can I use the conservation of mass to explain why the pressure difference? I notice that the longer path theorem does not seem to be the proper way to explain it.
The correct answer is the DC-3. This aircraft first flew in 1935 (Wikipedia). During World War II, many civilian DC-3s were drafted for the war effort and nearly 10,000 military versions of the DC-3 were built under the designation of C-47.
After the war, thousands of surplus C-47s were converted to civil service and became the standard equipment of almost all the world*s airlines. They remained in front-line service for many years thereafter. The ready availability of ex-military examples of this cheap, easily-maintained aircraft (it was both large and fast by the standards of the day) jump-started the worldwide, post-war air transport industry.
Numerous attempts were made to design a "DC-3 replacement" but no single type could match the versatility, rugged reliability and economy of the DC-3 and it remained a significant part of air transport systems, well into the 1970s. Even today, over 70 years after the DC-3 first flew, there are still small operators with DC-3s in revenue service. Its ability to start and land on grass or dirt runways also makes it popular in developing countries, where the runways may not always be a paved surface.
A DC-3 as operated by Rovos Air in South Africa (June 2006)
Regarding your query on the theory of flight, you can explain it by using the Bernoulli*s theory or “Hump theory” first, then expand on how a plane can fly inverted by using the aerodynamic law of lift. This can be explained by one of Newton*s Law - see my answer to a previous FAQ.