Thanks for looking into the cw-scedule Kilrah. It actually explains it all. The tailcones on most aircraft are, as the entire A/C itsself is too, well thought threw designs. Sometimesthe engineers try something new just to find out that there is too little improvement for a "retro-fitting". The induced drag that results from the relative small flat area is negligible to the light improvement of a tapered tailcone (if you have a look at the cw numbers). The improvement of cw would be in an area of max.0,02 and only at the very end of the tailcone. The new place for the exhaust will cause a negative change in airflow at its new location. In the end you need to have an exhaust somewhere and wherever it is it cares for a slight amount of drag. A lot of designs have the exhaust at the end such as the A318
or the 787
. Since those include the newest designes I will dare to say that that solution is the best.
QUOTE(Aspiring Boeing + Airbus Pilot)
Blended winglets cost nearly $1 million a set. So any other drag reducing devices would cost a lot too.
That analogy of yours is to be treated carefully. Even a simple idea and an easy implementation of which can have positive effects on the drag. It doesn't necesarily have to be expensive although most A/C parts are.