Jet engine

This is more of a speculation rather than something real, however, since this blog is just a brain storming game, I'd rather say it.

Modern commercial jet engine is more efficient than it's predecessor due to external compressed air flow. Here you see the new

and an old one

It happens, I guess, because of the larger funnel which prolongate the hot air in linear direction. The longer the tail the more pressure on exhaust cone which push the plane. 

If this long hot air effect is essential, it could be useful to think of such engine type:

The main compression and fuel injection 1 is the same except the size - it should be enlarged to redirect part of the air inside - into internal part of the exhaust 2. 

Overall the exhaust system should be longer to make the flow more linear, like rifle to pistol. 

To increase the funnel effect I suggest to make tor-like exhaust system. And to make the nozzle even longer the high dense pressure air flow 6 may create the wall - the same as Dyson hand drier with very narrow air flow.   The general high pressure support air is also help to extent the funnel.

In case the engine require more air, the extra front size, probably better to take from air intake located above the wing - making less pressure = more air lift, however I will say more it tomorrow.