engine reverse thrust

[derlokmerlo]

Hi everybody,

My name is Federico and I'm working as an environmental consultant,

in this moment I'm working on a Carbon footprint assessment for an airport, In particular I have to assess the co2 emission of the aircraft in the LTO cycle

I have some question and I hope you can answer it:

- what is the engine reverse thrust? there are Co2 emission connected with this procedure ( maybe in fuel consumption connected with the ERT)

- what is the pahse of taxiing? ( form the terminal to the take off way?)

- what should mean the APU and PCA phase?


thank you in advance.

Federico

[fredgrav]

Hi derlokmerlo,

1. Reverse thrust can be easily described as a reverse in direction of the gas flow which in turn reverses the thrust component. By generating an extra-high drag component, the new "forward" thrust component helps the aircraft deceleration thus reducing its stopping distance.
As far as I know, the CO2 emissions are the same as in normal thrust. It has been proved that CO2/HC/CO emissions are significantly lower with the least number of engines running (new reduced engine taxi procedures are being implemented nowdays).

2. There're 2 taxiing phases: Taxi-in is the ground distance to the gate, covered by an aircraft after landing; Taxi-out is the ground distance covered by an aircraft from the gate to the runway.

3. APU (Auxiliary Power Unit) is a gas-turbine engine generator able to provide the necessary power to meet the demand of either the electrical, hydraulic and pneumatic systems.

What you mean for PCA phase ?! ... afaik PCA is the Principal Component Analysis, that is nothing more than a mathematical procedure.

Hope that helps,
fredgrav

[derlokmerlo]

thank you so much!

i don't know what they means for PCA but it should be connected with the co2 emission of an aircraft I suppose.

have a good day Federico.

[fredgrav]

i don't know what they means for PCA but it should be connected with the co2 emission of an aircraft I suppose.

PCA is a mathematical process dealing with statistics that can often be expressed in graphs. I believe the PCA you're talking about has to do with a specific CO2 research about engines emissions.

Una buona giornata anche a te ! ;)
fredgrav

[Piltdown Man]

One of the lowest emitters of CO2 at an airport are the aircraft. The guilty parties are building heating, lighting and air-conditioning then we have the tugs, GPU's, Busses, Airport lighting systems - but remember, the really naughty boys are the cars that people drive to the airport in.

To reduce the carbon footprint of aircraft, remove speed and descent constraints which means we'll fly economy speeds and profiles at all times, allow visual approaches which means we'll spend less time in the approach phase and if you provide quality fixed electrical power and air-conditioning at a sensible price, airlines will use that instead of using an APU when parked.

Unfortunately, Green Ringpieces and rapacious bean-counters tend to get inside airport management which results in pointless rules, restrictions and procedures giving rise to huge carbon footprints but fat bonuses for those driving policy.

PM

[Milt]

Does anyone know the the amount of reverse thrust versus forward thrust at same engine RPM for a typical installation?

I would guess about 50% or even less.

[rottenray]

Folks,

~ 2 pages of extra reading material here... (http://www.pprune.org/search.php?searchid=6429420)

Have fun!

[zzuf]

With cold air only "reversed" probably a lot less than 50%. The major retardation work of reverse thrust is that done by reducing the velocity of the engine mass flow to about zero wrt the aircraft itself. So a (really) simple analogy, ignoring the hot gasses, is of each engine being similar to a drag chute but with, about, a constant mass flow. Hence, like a drag chute, the retardation effect reduces with speed.

[Intruder]

Best estimate for an engine like the CF6 is 40% net. N1 is limited, and the non-reversed hot section opposes the reversed fan flow.