Max Q
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Another AF1 Question

Thu Jul 05, 2012 5:05 am

Noticed in the picture of the VC25 departing Boston that it lacks the more aerodynamic -400 wing to body fairing installed on some of the latest classics before they halted production.



Considering what 'top of the line' heavily modified Classics these were I am surprised these were not included.



Anyone know why ?
The best contribution to safety is a competent Pilot.
 
rfields5421
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RE: Another AF1 Question

Thu Jul 05, 2012 2:34 pm

The VC-25 aircraft are late series B747-200 aircraft with elements of the B747-300 updates included.

The airframes were completed before the -400 wing to body fairing was designed and tested.

Going back and revising the aircraft would have delayed their delivery, not the mention the hassle of dealing with the USAF and US Secret Service design and security reviews.
 
Max Q
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RE: Another AF1 Question

Fri Jul 06, 2012 7:35 am

Quoting rfields5421 (Reply 1):


The VC-25 aircraft are late series B747-200 aircraft with elements of the B747-300 updates included.

The airframes were completed before the -400 wing to body fairing was designed and tested.

Going back and revising the aircraft would have delayed their delivery, not the mention the hassle of dealing with the USAF and US Secret Service design and security reviews.

Understand what you are saying but there were several late model Classic 200 and 300 series built with the -400 wing to body fairing.


And the VC25 was a very late model !
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kanban
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RE: Another AF1 Question

Fri Jul 06, 2012 8:28 pm

where a commercial operator may have seen a benefit in doing the modification, there was no economic sense to waste the funds on the two VC-25's
 
Max Q
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RE: Another AF1 Question

Fri Jul 06, 2012 11:41 pm

Quoting kanban (Reply 3):
where a commercial operator may have seen a benefit in doing the modification, there was no economic sense to waste the funds on the two VC-25's

Wadrs these were probably the two most expensive 747 Classics ever made !



I doubt economics was a consideration.



Anyone know the real reason ?
The best contribution to safety is a competent Pilot.
 
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kanban
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RE: Another AF1 Question

Sat Jul 07, 2012 3:41 am

Quoting Max Q (Reply 4):
Anyone know the real reason ?


Am not sure what you are seeking..
from personal experience within the company, the government never asked for pretty changes to the airframe, only those items related to security, communication and reliability. The fairing is a cosmetic issue.

Now structurally to make the change requires more than just marrying a new fairing to existing substructure... by why.. even though I stated above that a commercial operation might change, I have no knowledge of one actually doing it. I don't think there were any wheels up landings that required replacing all that with current production parts.
 
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747classic
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RE: Another AF1 Question

Sat Jul 07, 2012 9:11 am

Both VC-25's were delivered in 1990 (after major modifications) but are actually built and delivered "green" from the Final Assembly Line (FAL) to Boeing Military Airplanes in 1987, far before the introduction of the 747-400 series on the FAL.

Aircraft data :

MSN--------L/N----------F/F----------Test Reg------Reg.-----Operator----Del. date-----Type
23824------679------05.16.87-------N1788B-----82-8000-----USAF-----08.23.90----747-2G4B
23825------685------10.29.87-------N60659-----92-9000-----USAF-----12.20.90-----747-2G4B


The wing root was changed with the introduction of the -400 series (L/N 696).

The first 747 classic, with the new wing to body fairing, was L/N 704 , a 747-336 combi for Egypt Air.
Thereafter all 747-200 and -300 series were factory built with this re-contoured wing to body fairing, decreasing drag by 0,5%.


All 747 classics (including both VC25 aircraft) built before L/N 704 have the old type of wing to body fairing installed.


Remember that during 1989-1991 the -200,-300 and -400 series were assembled at random at the same final assembly line. In fact this factory modification was part of the 747 product improvement program (PIP) and not only for the 747-400 series.

No commercial operated 747-200/300 aircraft was ever retrofitted with this feature, because of the relative high modification costs versus the calculated fuel saving during the remaining economical life expectancy.
Boeing produced a master change proposal (5700MK4003) but nobody purchased it.
This masterchange not only contained the actual changing of the fairing but also two new escape slides for the No. 2 main entry doors (the new fairing extended further forward, underneath door 2) and some pneumatic duct changes inside the wingroot.
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kanban
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RE: Another AF1 Question

Sat Jul 07, 2012 4:00 pm

Quoting 747classic (Reply 6):
Thereafter all 747-200 and -300 series were factory


Thanks for refreshing my memory... I'd forgotten about that multi derivative line.
 
David L
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RE: Another AF1 Question

Sat Jul 07, 2012 6:13 pm

Quoting 747classic (Reply 6):
a 747-336 combi for Egypt Air

[Adopting pedant stance...]

Going out on a limb here but that wouldn't have been a -366 by any chance?

[... and... rest]
 
Max Q
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RE: Another AF1 Question

Sat Jul 07, 2012 8:53 pm

Quoting 747classic (Reply 6):


Both VC-25's were delivered in 1990 (after major modifications) but are actually built and delivered "green" from the Final Assembly Line (FAL) to Boeing Military Airplanes in 1987, far before the introduction of the 747-400 series on the FAL.

Aircraft data :

MSN--------L/N----------F/F----------Test Reg------Reg.-----Operator----Del. date-----Type
23824------679------05.16.87-------N1788B-----82-8000-----USAF-----08.23.90----747-2G4B
23825------685------10.29.87-------N60659-----92-9000-----USAF-----12.20.90-----747-2G4B


The wing root was changed with the introduction of the -400 series (L/N 696).

The first 747 classic, with the new wing to body fairing, was L/N 704 , a 747-336 combi for Egypt Air.
Thereafter all 747-200 and -300 series were factory built with this re-contoured wing to body fairing, decreasing drag by 0,5%.


All 747 classics (including both VC25 aircraft) built before L/N 704 have the old type of wing to body fairing installed.


Remember that during 1989-1991 the -200,-300 and -400 series were assembled at random at the same final assembly line. In fact this factory modification was part of the 747 product improvement program (PIP) and not only for the 747-400 series.

No commercial operated 747-200/300 aircraft was ever retrofitted with this feature, because of the relative high modification costs versus the calculated fuel saving during the remaining economical life expectancy.
Boeing produced a master change proposal (5700MK4003) but nobody purchased it.
This masterchange not only contained the actual changing of the fairing but also two new escape slides for the No. 2 main entry doors (the new fairing extended further forward, underneath door 2) and some pneumatic duct changes inside the wingroot.

Thanks for the great information 747Classic.



It all makes sense now. !
The best contribution to safety is a competent Pilot.
 
PC12Fan
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RE: Another AF1 Question

Sun Jul 08, 2012 11:07 pm

Quoting kanban (Reply 3):

where a commercial operator may have seen a benefit in doing the modification, there was no economic sense to waste the funds on the two VC-25's

Yea, the government has plenty of other programs to blow that money on!   

True, it could have been done, but overall, it would have been a waste of resources. Us "1%" would have thought it would have been cool and a good upgrade. The other "99%" just see the pretty aircraft that just happens to carry the POTUS and wouldn't know a fairing from a nacelle if it hit them in the face.
Just when I think you've said the stupidest thing ever, you keep talkin'!

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