Would I be right in thinking that at least some designs are highly visible - I think it’s a 737-200 that I’ve been sat in a rear window seat and seen large semi-cylindrical section swing back and into an angle behind the engine.
One particular design used on older low-bypass turbofans, such as those on MD-80s and other aft-mounted engines had a particularly visible design. The entire aft cowling would split in two and swing backwards until it formed a sort of “umbrella” shape. You had to be watching from outside the aircraft, as there aren’t any windows or seats that far aft.
Highly possible. They are similiar to but not quite the same as those in the link in post #6
Maybe it’s exactly true, I don’t know, but this almost sounds like a joke.
Actually it’s all true (apart from the blosker doors) . Should be blocker 
That’s the one - somehow I missed that link :smack:
::: Sigh:::
I’m at work, short on time so I cut to the chase.
Should have know this bunch wouldn’t let me slide. :smack:
Anyway I don’t design engines, I teach guys how to work on them. The four cycles in an Otto cycle engine are:
Suck
Squeeze
Bang!
Whoosh
So you guys be very afraid, the guy working on your car was taught by me!
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- Consider this: a jet engine is at least three sections: a compressor, a combustor and an exhaust turbine stage. If the pressure/temperature from the exhaust-section of the engine was ever greater than the pressure from the intake section, then air would start flowing backwards through the engine.
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- Yes it is true that you can generate thrust just by expelling gas–but it is enormously inefficient, and as somebody pointed out, large-jet turbofans usually only divert their fan rear flows with reversers. They don’t even bother with the turbine exhaust, as it is so small it is seen as insignificant. My point is that since the forward thrust is really occurring in front of the fans, if you really wanted to stop the fans from generating forward thrust you would be better off stopping air from getting into the fans from the front than you would by doing anything with the air getting blown out the rear.
~
Gas turbine engines don’t use the Otto cycle. They use the Brayton cycle.
But… You don’t want to stop generating forward thrust just yet, in case you need to TOGA (take off and go around) or otherwise abort the landing, which is why aircraft generally touch down with the engines at or close to full throttle.
I’m not a pilot, but the landing sequence is generally along the lines of:
Approach runway at low speed with full flaps (to lower the stall speed)
Flare
Push throtles up *
Deploy reversers *
Touch down
Commit to landing
Cut engine power
Apply wheel brakes
- Something that hasn’t really been touched yet is that in addition to the increased noise simply from running up the thrttle, the reversers add their own noise as they disrupt the exhaust flow from the engines.
Whoa, there… in every commercial landing I’ve been in, I have most definitely felt the mains rolling on the surface (sometimes after one or two bounces) before feeling by either noise, vibration or deceleration that reverse thrust was applied. Is that an illusion?
I suppose I should add to this thread that I have once flown on an airline where they gave an explanation to expect the ‘sudden noise’, during the pre-landing patter. Can’t remember the airline, though, because it was a stand-in for Ryanair. (Which in itself could be humourous…)
if you deploy the reversers before touching down, you will stall the plane and it will fall to the ground. This is considered a bad thing, and could be the difference between a good landing and a great landing*
Having watched the thrust reversers deploy on more airplane flights than I can count, I can say for a fact that the main gear is on the ground before the reversers come on/open, and power is applied.
*A good landing being one where you walk away from it. A great landing is when the can use the airplane again
You forgot the fluegel valve. And the blinker fluid.
I like that, as a motto for air travel in general
Isn’t that what the British told anyone who enquired about Frank Whittle’s aircraft when it first flew to put them off figuring out the idea behind it?
I am well aware of this; I mentioned it rather early on, in fact. It is not, however, the pressure differential that drives the engine forward, it is the reaction mass expelled from the rear. You could cover the air intake completely and feed pressurized O[sub]2[/sub] from an onboard tank to the compressor instead, and the engine would basically function the same. In fact, this is called a rocket.
I would guess the fan exhaust has a higher speed (because the exhaust nozzle is smaller than the intake duct), and therefore contributes more to the thrust.
Most of the thrust in a high-bypass turbofan comes from the fan simply because of the higher volume of air it’s moving, not from its velocity.
The Brayton cycle is also suck-squeeze-bang-blow, it just involves moving the air along instead of keeping it in the same place like an Otto-cycle engine.
You would indeed. Older low- and medium-bypass engines are usually fitted with the “clamshell” type reverser you see on 737-100’s and -200’s and on DC-9/MD-80 versions. acsenray, I assure you the description is no joke.
pushkin, yes, that’s the legend.
JRDelirious, you’re right, the squat switch (when it’s working) on the landing gear prevents reverser unlatching unless weight-on-wheels is detected. It’s also shown in the cockpit, at least on some aircraft, by a light labeled “WOW”.
Around these parts, we give the list as:
Suck
Squeeze
Bang
Blow
(It kinda sounds like the shot list for an adult film 
)