[AR] Re: to the stars, soon

  • From: Dave McMillan <skyefire@xxxxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Sat, 2 Apr 2016 12:58:00 -0400



On 4/1/2016 11:53 AM, Paul Mueller wrote:

Really? So the material between the intake and the engine mount (say on a wing-mounted turbojet like on a B-52) is under tension, and if the intake broke free it would go shooting forward? I'm not saying that's wrong, I just don't understand that.


Well, I can't speak to turbojets, specifically, but when I was working on thrust reversers (production equipment, not the reversers themselves) for high-bypass turbofans at AirBus, the (layman's) explanation that I was given was that 70-80% of the thrust of a turbofan is essentially the primary intake fan acting like a propellor, and only 20-30% was "hot gas" thrust from the combustor stage, and the outer cold flow was what the thrust reverse interacted with. The "hot" part of the engine primarily contributed to thrust by providing the energy to keep the front fans turning.
Granted, it was an explanation from a non-propulsion guy to a non-aerospace guy, and it was a few years ago, so I'm probably mangling that somewhat. That was a fun gig, though, especially standing next to some finished engines at the end of the production line and watching fans big enough to swallow a Buick spin under the influence of a breeze that was probably less than 3km/h.

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