ConcordeBoy From , joined Dec 1969, posts, RR: Posted (8 years 11 months 1 week 15 hours ago) and read 4353 times:
DfwRevolution got me thinking about this...
...since these engines will be nigh-bleedless, and no other aircraft currently can utilize such a system: how will GE/RR flight-test the new 7E7 engines??
DfwRevolution From , joined Dec 1969, posts, RR: Reply 2, posted (8 years 11 months 1 week 15 hours ago) and read 4118 times:
I'd like to know how I inspired such thought, as you've stupified me as well...
I guess GE will just use the 747 engine testbed. That aircraft has 3 other engines off of which to divert bleed-air, and all that must be tested is the electrical output of the engine right? The single GENEX will probably juice out more voltage than the other three engines combined, but that's what the 7E7 needs.
BoeingBus From United States of America, joined May 2004, 1588 posts, RR: 18 Reply 3, posted (8 years 11 months 1 week 15 hours ago) and read 4108 times:
But I can see where he is coming from... never thought of that...
But agree it would have to be a modified 4 engine plane like a 747 that would allow all the pneumatic controls to be powered on 2 classic engines and the other 2 would be 7E7 test engines.
That's a great picture for getting the scale of the GE90 against existing 747 engines
But agree it would have to be a modified 4 engine plane like a 747 that would allow all the pneumatic controls to be powered on 2 classic engines and the other 2 would be 7E7 test engines.
The testbed would generally only carry one test engine in case of a fault developing with both experimental engines. That's why a 747 testbed would have three standard units, to ensure safe operation.
WhiteHatter From , joined Dec 1969, posts, RR: Reply 8, posted (8 years 11 months 1 week 15 hours ago) and read 4037 times:
...I'm curious as to how Boeing will test the various associated systems (that will sustain human life sans engine-bleed) in an actual flight?
Probably on the 7E7 prototype, with the test crew outfitted with breathing apparatus.
They could also adapt one or two of their in-house aircraft to test out certain components before the prototype is assembled. The only systems which will need to be tested are pressurisation and heating components, and they do have experience in non-bleed-air pressurisation from years ago as well.
Early 707s were not pressurised using bleed air. They had separate compressor assemblies.
DfwRevolution From , joined Dec 1969, posts, RR: Reply 9, posted (8 years 11 months 1 week 15 hours ago) and read 4007 times:
Your last reply on this thread
Lol.. I'll be damned.. anyway this is an interesting line of thought you have raised. But don't think I deserve credit for triggering it
...I'm curious as to how Boeing will test the various associated systems (that will sustain human life sans engine-bleed) in an actual flight?
Most likely through a combination of ground testing, testbed testing, and 7E7 certification. Boeing can test the enviornmental system on the ground, test the engine on the 747 testbed, then certify the two together on the actaul airframe.
Given the accuracy of computer simulation and that new versions of CATA allow Boeing to simulate system interaction, and with test results from both the engines and enviornmental systems in hand, Boeing should have a good idea of how the system will work far before roll-out. Then a rigerous certification regimine, Boeing should be able to prove the system.
The bleedless systems of the 7E7 will definitly be one of the most challenging aspects of 7E7 development. An analogy might be drawn between the 777 and ETOPS development and the 7E7 and bleedless development.
Probably on the 7E7 prototype, with the test crew outfitted with breathing apparatus.
Well if they need breathing devices, other than just out of precaution, Boeing might have some certification issues to work out...
A380900 From France, joined Dec 2003, 1006 posts, RR: 1 Reply 13, posted (8 years 11 months 1 week 12 hours ago) and read 3815 times:
The test engine need not be compatible with the remaining three. As Airbus points out about the Trent 900 testbed, it works with 5000 psi systems whereas the three other engines work with traditional 3000psi.
They have the entire empty aircraft to create a setting which makes the new engine working although it is different from the rest. Not a big challenge in my view.
Vorticity From United States of America, joined May 2004, 337 posts, RR: 5 Reply 14, posted (8 years 11 months 1 week 11 hours ago) and read 3789 times:
It seems for the 777 program, they tested their Trent 800 on a Boeing 747 testbed. I found the information burried at the bottom of this webpage.
WhiteHatter From , joined Dec 1969, posts, RR: Reply 16, posted (8 years 11 months 1 week 1 hour ago) and read 3513 times:
It seems for the 777 program, they tested their Trent 800 on a Boeing 747 testbed.
They used the prototype 747. It had, until recently at least, stickers on the forward fuselage showing that it had been used in the Trent 800 trials
When Rolls flight tested the first RB211 engine, they used a VC10 with 2 engines removed. Unfortunately that aircraft had to be written off as the imbalance twisted the airframe out of shape!
FTOHIST From United States of America, joined Mar 2004, 73 posts, RR: 0 Reply 17, posted (8 years 11 months 1 week ago) and read 3492 times:
It'll be tested in the #2 position, just like all the other test engines (with the exception of the CF34-8 in the ferry position, of course). Look for some MAJOR mods to the existing electrical load simulation system, which may include adding some fairly large bumps to the fuselage. I'd say it will be about the most ambitious flight test program seen on that airplane, and probably its last before retirement, since it can't carry a more powerful GE90 than the -115B.
Vorticity From United States of America, joined May 2004, 337 posts, RR: 5 Reply 18, posted (8 years 11 months 1 week ago) and read 3431 times:
They used the prototype 747. It had, until recently at least, stickers on the forward fuselage showing that it had been used in the Trent 800 trials
Hmm, last I saw that plane was in 2000, it was sitting next to a parking lot of Boeing Field, got a cool picture of my car with the 747 as a backdrop. I think it had all 4 engines off. I'm not sure if it's in flying condition anymore or not.
Unfortunately that aircraft had to be written off as the imbalance twisted the airframe out of shape!
WhiteHatter From , joined Dec 1969, posts, RR: Reply 19, posted (8 years 11 months 6 days 23 hours ago) and read 3384 times:
Hmm, last I saw that plane was in 2000, it was sitting next to a parking lot of Boeing Field, got a cool picture of my car with the 747 as a backdrop. I think it had all 4 engines off. I'm not sure if it's in flying condition anymore or not.
It'll eventually be fully restored and parked undercover. There are plans to extend the museum at Boeing Field to bring it and the 727/737/Concorde etc into a new building.
There are some pictures of the RB211 test bed and more info here
Caetravlr From United States of America, joined Oct 2000, 898 posts, RR: 1 Reply 20, posted (8 years 11 months 6 days 23 hours ago) and read 3225 times:
Is any of the technology being used for the bleedless systems on the 7E7 available from any military experience that they may have? I know that a lot of their planned use for composites has a military background, but I was wondering about any of the new power systems they are planning? I wouldn't guess that it would, but it would be interesting to know.
A woman drove me to drink and I didn't have the decency to thank her. - W.C. Fields
CXA340 From United States of America, joined May 2004, 51 posts, RR: 2 Reply 21, posted (8 years 11 months 6 days 21 hours ago) and read 2903 times:
Excuse my ignorance...but what exactly is the difference with the new 7E7 engines compared with other models? I realize some of the basic engineering differences Boeing has talked about, but why make the engine completely bleedless? Will this mean a different way of starting the engine? And then, to follow up on a previous post, then would this mean entirely new systems for the interior since they will not be bleeding air off of the engines? Will this plane be more electrical in nature than mechanical?
WhiteHatter From , joined Dec 1969, posts, RR: Reply 23, posted (8 years 11 months 6 days 21 hours ago) and read 2824 times:
Electrical systems are more efficient than compressed air systems.
There is a weight saving as well as increased flexibility on what machinery goes where. Complex pipe and hose assemblies from the engines are eliminated.
Caetravlr From United States of America, joined Oct 2000, 898 posts, RR: 1 Reply 24, posted (8 years 11 months 6 days 21 hours ago) and read 2806 times:
Based on what WhiteHatter says, then not only will the plane weigh less, but it will also be more efficient, because (if I understand this correctly), that bleed air that is sucked off the engines takes away from the actual thrust that is being used to propel the aircraft. Is that right? This would mean that the engines are more efficiently propelling the jet.
A woman drove me to drink and I didn't have the decency to thank her. - W.C. Fields
25 ConcordeBoy: This would mean that the engines are more efficiently propelling the jet. Correct, among other things
26 Okie: Look for some MAJOR mods to the existing electrical load simulation system, which may include adding some fairly large bumps to the fuselage General E
27 Phollingsworth: Look for some MAJOR mods to the existing electrical load simulation system, which may include adding some fairly large bumps to the fuselage General E
28 Blackbird1331: What the hell was it bleeding? Throw it it on a 757 and get it done with.
29 Alessandro: If they would like to be on the extra safe side they could use the AN-225 and only replace one of six engines....
30 Vorticity: What the hell was it bleeding? Throw it it on a 757 and get it done with. Probably can't fly the 757 on only one certified good engine.
31 FTOHIST: Yeah, that's what the airplane is doing in HAECO right now-having "GE Transportation" painted on it instead of "GE Aircraft Engines". So, now it can a
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