cancidas
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Nasa B747 Shuttle Carrier

Fri Sep 17, 2004 5:41 pm

i was just wondering about this aircraft/ shuttle configuration. a few things i'm curious about is how is the center of gravity affected with respect to rolling the a/c? did the pilots not roll it completely to avoid strange overloading the wing? i'm not engineer but i doubt that the 747 was designed to fly with that thing strapped to it's back.
"...cannot the kingdom of salvation take me home."
 
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vzlet
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RE: Nasa B747 Shuttle Carrier

Fri Sep 17, 2004 8:39 pm

Not sure what you mean by "roll it completely", but I assume you're not talking about aerobatics. I saw the combination fly at Paris and, while the 747 crew wasn't horsing their plane around the sky, they didn't seem to especially baby it either. They even did a touch-and-go.

-Mark
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DfwRevolution
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RE: Nasa B747 Shuttle Carrier

Fri Sep 17, 2004 11:48 pm

As I understand it, the shuttle wing provides a little lift of its own, so the structural loads on the aircraft are actually stronger when the SCA is parked. As for center of gravity, the shuttle is planted directly over the midportion of the fuselage and hell trim ballast could easily compensate for any other imballance.

did the pilots not roll it completely to avoid strange overloading the wing?

The shuttle (empty) weights about 150,000 lbs which is only slightly beyond the limits of a regular stock-built 747. With the modifications NASA has done, it can carry the shuttle safely and easily.
 
dl021
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RE: Nasa B747 Shuttle Carrier

Fri Sep 17, 2004 11:55 pm

The 747-123 in the web site below is an ex-American Airlines bird that NASA uses and it takes the load just fine, but I have never heard of somebody rolling the airframe. There are two Shuttle Carrier Aircraft and they can be seen on the following website.

http://www.dfrc.nasa.gov/Newsroom/FactSheets/FS-013-DFRC.html
This is NASA's web site on the SCA

http://groups.msn.com/SpaceCowboySaloon/nasaaircraft.msnw
This site has some good photos of the airplane in flight as well as some of the shuttle being loaded.

[Edited 2004-09-17 16:56:39]

[Edited 2004-09-17 17:00:03]
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SATL382G
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RE: Nasa B747 Shuttle Carrier

Sat Sep 18, 2004 2:01 am

Cancidas is talking about the "height" of the CG rather than its position fore and aft as we normally think of CG in a transport aircraft.

This increase in CG height means the roll axis is also displaced upwards.
Think top heavy boat rolling in a swell if that helps the word picture.

I'm no engineer either. Seems to me though the increased height of CG would not be much of a problem for a transport aircraft flown very gently vs a fighter were manueverability is so important. The STA doesn't fly far or in inclement weather with the Shuttle on it's back.

SATL382G
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cancidas
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RE: Nasa B747 Shuttle Carrier

Sat Sep 18, 2004 12:56 pm

very good SATL382G! what i'm thinking of is are the roll and yaw axis affected by the displacement of the cg? see now today i'm not so tired so i cna actually think and form a full, well-thought-out sentence
"...cannot the kingdom of salvation take me home."
 
SATL382G
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RE: Nasa B747 Shuttle Carrier

Sat Sep 18, 2004 1:20 pm

Any change in the CG is going to have an impact on roll, pitch, and yaw axes -- It's a question I think of how much impact.

I thought about the yaw aspect when I was typing the other post.. But that caused my brain to hurt  Smile/happy/getting dizzy so I left it out. Could be the reason for the fins on the horiz. stab, but I thought the fins were augmenting a blanked out vertical stab.

... and, more brain hurt, doesn't this all factor into yaw coupling?

SATL382G
"There’s nothing quite as exhilarating as being shot at and missed" --Winston Churchill
 
cancidas
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RE: Nasa B747 Shuttle Carrier

Tue Sep 21, 2004 10:08 am

jeez... this is why i'm not in engineering. the more you think about it the more physics it involves. ugh... i just wanna fly!
"...cannot the kingdom of salvation take me home."

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