First fligh of the Trent 900 engine

“Boeing also want to run all of their electrical power off of the engine aswell, and not have to carry anything such as batteries on board”

The electrical power for the aircraft comes from a generator connected to the engine gearbox. If there is an engine failure, the APU can be brought online to provide some engine power… On the 777, the APU and the each engine is designed to produce the same amount of elecrical power, so if the engines fail, something is going to have to be switched off! If the APU fails, then there is a RAT, or ram air turbine which produces power like a windmill… this only produces a small amount of power, only enough to maybe power the flight instruments. If that fails, then I think there are smoe batteries somewhere… not sure if the RAT or batteries provide the last of the power! But the chances of all of these failing are very remote, so perhaps Boeing could get rid of the batteries.

I’m sure it’s still there, just not lowered.

So I take it that the whole bogie assembly is removed not just deactivated by means of software input?.

on the second picture of the A340, where is the center main wheel, it aint got one?.

“a large amount of the energy is actually created without having to use any fuel at all”

You never get something for nothing in the aviation world!! Most of the air passes through a bypass duct after passing through the fan, the fan, which sends the air backwards is driven by a turbine stage, to turn the turbine you have to use fuel!

With Jet engines, there’s basically 2 ways to get thrust, either you put a large mass of air through the engine at a relatively slow speed (bypass turbofan), or you send a small mass of air through the engine at a high speed (turbojet).

For civil airliners the former is preferred because it increases the propulsive efficiency, which depends on the difference between the velocity of the air coming out of the back of the engine and the aircraft forward velocity, so the closer these two velocities are, the better the propulsive efficiency.

The overall efficiency of an engine is the propulsive efficiency multiplied by the thermal efficiency. The thermal efficiency is the kinetic energy of the air through the engine(useful work out) divided by the work put in by the fuel (energy in). The thermal efficiency gets higher when the temperature is higher, but there are material constraints here, materials can only take temperatures up to… I think 1700K is the standard Turbine entry temperature at the moment.

The down side to the turbofan is that it’s got a large diameter, so produces more drag. The turbojet which produces less drag is noisier, and is more efficient as the airspeed goes up into the supersonic regime.

That OK? Man reading that you can tell I’ve been busy revising for my Turbomachinery exam!!

Were the very first jet engines also so advanced (around 1950)?

You could say they were, as everything was a lot more complicated back then. In those days they tended just to have the single shaft and compressor, meaning that to produce the same amount of power, a higher amount of fuel and input was needed. Nowadays, they have more efficient ways of producing the power. In most modern airliners, they use a bypass system, where a large amount of the energy is actually created without having to use any fuel at all, and air is simply fed through the outside area of the engine. As you can probably tell, I’m no expert on this! GZYL could probably elaborate a lot more, I’m just trying to remember things I’ve picked up in books over the years.

I think that is the plan wth the Trent-1000 GZYL. With the -900 they are already having to combat a lot of new ideas that Airbus want. RR have found themselves a bit stuck at the moment though, because unless they find other composites, they’ll have to use more material to make it stronger. More material means more weight, and for every 1kg extra that RR use, they will be charged £10,000 by Airbus.

With the -1000 they are going to need to make it more efficient in the way you mentioned. However, it seems that Boeing this time are expecting too much. They want to have a 20% more efficient engine, which they may be able to achieve if it was designed like that. But, Boeing also want to run all of their electrical power off of the engine aswell, and not have to carry anything such as batteries on board. That way, there is less weight and more room left in the plane to make it live upto it’s expectations.

Were the very first jet engines also so advanced (around 1950)?

Just thought of something else. RR could make the A380 more efficient than planned… this is due to this contra rotating shaft business. When air flows off a rotor blade in an engine, it comes off at an angle due to the rotation of the blade. The air then has to be turned back to a favourable angle by a guide vane to optimise the performance of the next rotor blade, and avoid the blade stalling. When moving between compressor stages the air has to be turned more when all shafts turn in the same direction than when the shafts move in opposite directions. Because the air is being turned less, less energy is being lost, as the air has more axial velocity. Also, the guide vanes needed to turn the air are larger when all shafts turn the same way, which leads to a decrease in weight.

Anyway, back to my point, the A380 can be made more efficient by having the fan turning in the opposite direction to the IP compressor which turns in the opposite direction to the HP compressor, and the same in the HP, IP and LP turbines. At present the A380 only has 1 set of contra rotating compressors and turbines. But RR is only doing what Airbus say… and is following required efficiency figures from Airbus. Now the Trent 1000 for the 7E7 will have each compressor and turbine contra rotating… loeading to enhanced efficiency.

Hope you follow that! 🙂

The fan blades are larger, there’s a contra rotating High pressure system in there which the 777 engine doesn’t have, that’s a new idea which leads to problems.

That makes sense, I was not aware of that. Thank you.

“Those are essentially newer, moderately larger 777 engines. Why would they be having so many problems with them?”

The fan blades are larger, there’s a contra rotating High pressure system in there which the 777 engine doesn’t have, that’s a new idea which leads to problems.

Those are essentially newer, moderately larger 777 engines. Why would they be having so many problems with them?

Could be a nice engine for the A330

Wow!! 😮

Wow! Absolutely huge. I met a guy on holiday, on the design team for the Trent-900 and -1000. He said they’ve been having lots of problems with the -900, as Rolls Royce are struggling to meet Airbus’ huge demands. Apparently, the fan blades carry on weakening in places that they never have before, and researchers are currently trying to find new composites that might stand up to the forces.

Looking at the engine makes you realise how big the A380 will be
cant wait to see the A380

I know what, put these engines on an A330 and then you can call it a plane. :p

yes, you’d better

:p …………

Hey!! I’ve had an idea!!

Airbus could put two of those on an A340 and call it the 7E7-400…………..

I’ll get me coat……………………..

yes, you’d better.

Hey!! I’ve had an idea!!

Airbus could put two of those on an A340 and call it the 7E7-400…………..

I’ll get me coat……………………..