Natwerk Designs

Why does the modern commercial jets does not have T-Tail and rear engine position designs such as MD-90?

I have noticed that almost all current commercial airliners are having a vertical tail rather than the old T-Tail designs. The engines are positioned under the wings instead of the rear of the plane. Smaller jets such as those from Bombardier are still using the T-Tail design. Why?

Public Comments

1. The jet engines found on today's twin engine passenger jets are just too big to fit on the rear of the fuselage. It's also easier to maintain an engine that's closer to the ground, under the wing. With the engines under the wing, theT-Tail configuration is not necessary, and the lower tail assembly is also easier to work on.
2. Airplanes with tail mounted engines require a heavier structure of fuselage than airplanes with wing mounted engines - Compare the empty weight of 2 almost similar airplanes except for the engine location - TU-124 and TU-134 - Another fact, long fuel lines (shrouded) are required to go from wing and belly tanks to the location of the engines in the tail, admittedly with potential of fuel leaks. Further, a catastrophic failure of turbine blades in the tail could seriously jeopardise flight controls (elevator/rudder) in the tail - Note also that T-tail airplanes could have bad stall characteristics (deep stall) and that air from the wing, at high angle of attack is sometimes disturbed when entering the engine inlets - The prototype of the Bac One-Eleven crashed because of such circumstances - All T-tail with tail-mounted engines airplane that I know, are equipped with "stick pushers" - I flew the 727 in the 1970s and 1980s - In that aircraft, there is always a danger of ice ingestion when (in flight) ice is removed from wing and fuselage surfaces by the anti-icing systems - I also had, in a 727-100, an engine failure when nº 3 engine ingested the thread of nº 4 failed main tire right at rotation for takeoff - Engines under wing tanks (lower location) can receive fuel by gravity in the absence of boost pump pressure when fuel tank boost pump fail - It is generally not possible to feed tail mounted engines without boost pumps - .
3. Both good ansers here. Engines back then (80s-93) were a good bit smaller than the ones today. However, the Airbus A320 has the same engine and has it mounted on the wing.