That is correct syscom. You can not have a RR on one side and a GE on the other.
First glimpse of the Boeing 787
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Disregarding the difficulties in flying.... it is possible to have a GE on one wing and a RR on the other...
It wouldn't be a simple case of swaping the engine, you'd also have to swap the strut as there are some differences in wiring within the strut, fire extinguishers and such.... So you're interchanging back to the strut disconnect point.
Even with that said there is a different set of drawings for the wiring up to this strut disconnet point for an RR engine and GE... so as always it's not a simple case of offering one up or the other.
As posted in an earlier thread this is RR T1000 engine on RR's flying test bed...a 747
http://www.ww2aircraft.net/forum/modern/boeing-dream-lifter-747-lcf-6494-2.html
So it is possible to have different engine, physical sizes of engine on different wings, I suppose as long as the pilot compensates for it ?
regards
Simon
It wouldn't be a simple case of swaping the engine, you'd also have to swap the strut as there are some differences in wiring within the strut, fire extinguishers and such.... So you're interchanging back to the strut disconnect point.
Even with that said there is a different set of drawings for the wiring up to this strut disconnet point for an RR engine and GE... so as always it's not a simple case of offering one up or the other.
As posted in an earlier thread this is RR T1000 engine on RR's flying test bed...a 747
http://www.ww2aircraft.net/forum/modern/boeing-dream-lifter-747-lcf-6494-2.html
So it is possible to have different engine, physical sizes of engine on different wings, I suppose as long as the pilot compensates for it ?
regards
Simon
syscom3
Pacific Historian
Aircraft used for testing engines are not a run of the mill military or civil aircraft, and are generally on eof akind test platforms.
Boeing used a single common strut to handle both engines as a way to save money.
Jugulator
Airman 1st Class
That is one ugly plane, but I bet it flies like a beaut.
FLYBOYJ
"THE GREAT GAZOO"
Conceivably its possible to co mingle engines on an aircraft such as the 787. The fuel management system, if set up to do so will take care of any differences in power settings the pilot may have to deal with.
Possible but not probable.
Possible but not probable.
syscom3
Pacific Historian
How about "uneconomical"
FLYBOYJ
"THE GREAT GAZOO"
In what terms? Operationally this shouldn't pose a problem and maintenance wise it would be a benefit. The FMS would ensure that each engine operated to its top efficiency. Unless there's something aerodynamically which would degrade performance, I can't see why this couldn't be done.
Personally as a pilot, I would rather have "two of the same."
No the 787 is the first aircraft that will allow you to just replace the engines. It has a common electrical interface for both engines.
syscom3
Pacific Historian
For one, different weights of the engine mean unbalanced wing loads, requiring less than optimum flight control settings. That cuts down on fuel efficency.
I dont suppose the drag ratio's of either engine is all that different.
And finally, logistics....... cheaper to have one set of spare parts than two.
FLYBOYJ
"THE GREAT GAZOO"
The weight is negligible between the two engines and the trim system (which is computer controlled) will take care of any "unbalance" (if any).
As far as logistics - most airlines lease their aircraft and engines. banks usually own them. There is a lot of "swapping" between airlines. Having the ability to interchange engines is actually a plus in this situation and it avoids "placing your eggs in one basket" as happened to Lockheed on the L-1011 many years ago.
As far as spare parts - again limited as most airlines no longer overhaul their engines, they send them out so only line maintenance parts will be stocked. I do know United uses a "dock to stock" system where only what is needed is actually orders. In this scenario only "rotables" (filters, gaskets etc.) might be engine specific. the impact on logistics will be minimal.
The Trent 1000 can also be "de tuned" to match the GE engine (If this was to be done)
Then I have to wonder if the strut wiring, the wiring between the strut disconnect and the engine disconnect is the same for both engines and whether this is an easy interchange operation.
The engines CoG are different... T1000 are a lot shorter than the GE engines...
Simon
FLYBOYJ
"THE GREAT GAZOO"
Engine C of G? Where did you come up with that? If the engine mounts are designed to fit the same point on the pylon, it doesn't make a difference. And its that way on many airliners designed to take on different engines. Once that engine is on that pylon it's part of the airframe and computed into the entire CG.
If you dont care to believe me on it, go and check out the Boeing website.
Yeh what would I know.... it's not like I have a 787 engine strut is it now...
Hey I only state facts from Boeing and its not like its something thats really hard to believe. I might not know everything but being an Aircraft Mechanic I find it easy eneogh to believe what a manufacturer says.
SoD Stitch
Banned
Makes sense . . .
To keep the A/C's CoG in the same place, the engines would probably have to mount in a slightly different place if their CoG's are different.
FLYBOYJ
"THE GREAT GAZOO"
Wrong.
The aircraft C of G has nothing to do with the engines C of G. Once attached to the airframe it all becomes one "moment" with the aircraft. Here's some info on weight and balance
http://www.faa.gov/library/manuals/aircraft/media/FAA-H-8083-1A.pdf
I could tell you that during engine installation, the CG is attained while hoisting the engine (I did a few, DC-9, DC-10, B-727 and B-737). I would also guess that both RR and GE engines have a similar C of G but either way once attached to the aircraft it has nothing to do with the over all aircraft C of G.
God I hated Weight and Balance!!!!
When we had an aircraft whos weight and balance was out of tolerance after some work or modifications were done or we added ballistic protection, etc.... sometimes it would take a whole day to figure it out. 9 out 10 times it was a math error!
FLYBOYJ
"THE GREAT GAZOO"
That's right - because once the engine is on the plane then only thing that matters is its weight and "moment."
That's calculated in the design of the pylon and that's why the pylon is so robust in its construction. As far as putting different engine types on the aircraft, the only thing a maintainer would have to consider is any change in weight and then calculate that in the aircraft's weight and balance records.
