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CCA
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The Latest GE90 On It's 747 Test Bed.

Sat Oct 26, 2002 1:37 pm

Check out the photo's here.

http://www.virtualfrontier.org/jeff/747engine.htm
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wannabe
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RE: The Latest GE90 On It's 747 Test Bed.

Sat Oct 26, 2002 2:09 pm

They are great shots!!! More Please. Where does GE do it's testing?
 
PPGMD
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RE: The Latest GE90 On It's 747 Test Bed.

Sat Oct 26, 2002 2:13 pm

At worst, you screw up and die.
 
Trent_800
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RE: The Latest GE90 On It's 747 Test Bed.

Sat Oct 26, 2002 2:50 pm

Thats one BIG bloody engine, slap 4 on a 747 and you have the worlds first VTOL airliner.  Smile
 
H. Simpson
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RE: The Latest GE90 On It's 747 Test Bed.

Sat Oct 26, 2002 3:08 pm

I agree with Trent_800. This GE90 is way to big for 747 man! The engine looks it as if it's gonna fall on the ground
 
Guest

RE: The Latest GE90 On It's 747 Test Bed.

Sat Oct 26, 2002 4:26 pm

Aircraft normally operating from Mojave, occasionally Victorville...
(s) Skipper
 
 
gotAirbus
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RE: The Latest GE90 On It's 747 Test Bed.

Sun Oct 27, 2002 12:02 pm

My goodness! That big?! Enough to make me hallucinate

Anyways, anyone notice the fans inside the engine (last pic)? Why is it in a wavy appearance?

(gotAirbus?)-(Got Commonality?)-(Have A Nice Flight!)
(gotAIRBUS?) - (Got Commonality?) - (Have A Nice Flight!)
 
wannabe
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RE: The Latest GE90 On It's 747 Test Bed.

Sun Oct 27, 2002 1:38 pm

Can anyone tell us the ground clearence under the engine during taxi? It looks like about 18 inches at best!
 
JMO-777
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RE: The Latest GE90 On It's 747 Test Bed.

Sun Oct 27, 2002 6:57 pm

there is a space of around 0.8 m (2feet10inches) between engine and ground if the 777 is fully loaden.

GreetZ,
Jan
~~~ Fly with a Triple Seven and you feel like in heaven ~~~
 
Trent_800
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RE: The Latest GE90 On It's 747 Test Bed.

Sun Oct 27, 2002 7:48 pm

GotAirbus,
The higher RPM the fan probabally runs at is the most biggest problem facing engine designers, because there is a point at which the blade tips become supersonic, this will cause most of todays fans to stall. My guess it that the curved fan is designed so that the tips dont stall when they go supersonic.
Trent_800
 
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fanoftristars
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RE: The Latest GE90 On It's 747 Test Bed.

Mon Oct 28, 2002 2:09 pm

From the book "Boeing 777, the Technological Marvel"...

"The curved blades slow down the formation of supersonic shock waves... This means flow across the blade, and therefore thrust, is improved without the need to increase the size and diameter of the blade..."

Hard to imagine that this fan would need to be any bigger. I hear the GE90-115 has an even bigger fan than the regular GE90.

This quote was describing the RR Trent 8104 which featured the same shape of blade, only the RR was made out of titanium completely.
"FLY DELTA JETS"
 
PPGMD
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RE: The Latest GE90 On It's 747 Test Bed.

Mon Oct 28, 2002 2:40 pm

It looks like we are nearing the maximum size for engines, and you can't just spin the blades faster, so does anyone know if anyone right now is working on adjustable pitch fan blades for jet engines. I heard that there were working on them in the past, but they just weren't pratical then, I wonder if we have reached the point where they might just work.
At worst, you screw up and die.
 
BR715-A1-30
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RE: The Latest GE90 On It's 747 Test Bed.

Wed Oct 30, 2002 9:09 am

AFAIK, You cannot make a Reversible pitch Turbofan. (Someone correct me if I am wrong) They had the GE-36 which was the UHB fan that had reversible pitch fans but that project was scrapped in the late 80s
Puhdiddle
 
Android
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RE: The Latest GE90 On It's 747 Test Bed.

Wed Oct 30, 2002 11:52 am

According to AWST report this aircraft did 330 kts with the 3 JT-9D engines at flight idle and the GE-90 doing all the pushing .
 
aeroguy
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Joined: Wed Aug 15, 2001 1:33 am

RE: The Latest GE90 On It's 747 Test Bed.

Wed Oct 30, 2002 10:03 pm

I haven't heard of anyone working on a variable pitch fan either. I'm not sure if it really gets you anything besides a big headache. A variable pitch fan would be more helpful in matching different altitude conditions but I think the effect is minimal, especially considering the increased complexity, cost and weight. The one notable advantage is that with a variable pitch fan you might be able to reverse the pitch and remove the need for a reverser. But yet again, good old cascade thrust reversers aren't as complex or heavy as a variable pitch fan.

Also, in regard to the 115B's wide chord swept fan blades... One way to think of the fan blades is in terms of a high speed aircraft wing. Thickness to chord ratio (t/c) is a critical parameter in determining drag divergence Mach Number, critical Mach Number, shock wave formation, etc. Obviously for high speed aircraft/blades you want t/c to be small. There's a feasible limit on how thin the blades can be structurally, so to improve t/c, increased chord is the way to go. Now out at the tips (as was mentioned) it's pretty hard to avoid supersonic flow and shocks. One approach to this problem is to treat the interblade airfoil passages as converging-diverging nozzles. Ideally you can minimize shock losses without limiting the amount of flow that can pass through the fan.
 
saab2000
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RE: The Latest GE90 On It's 747 Test Bed.

Thu Oct 31, 2002 2:37 am

I find it ironic that the GE test-bed aircraft is a 747-200 with the P&W engines rather than one with the GE engines.  Smile/happy/getting dizzy
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