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Topic: Max Payload On 747-400ERF Lower Than On 747-400F?
Username: BA
Posted 2006-10-21 21:03:30 and read 7840 times.

I was looking at this 747 Freighter brochure from the 2005 Paris Air Show and it struck my attention that with the higher MZFW option, the 747-400ERF has slightly lower structural payload than the 747-400F, 272,600 lb versus 273,300 lb.

http://www.boeing.com/news/feature/p...ts/bca_pdf/specs/747_Freighter.pdf

Why is this the case?

Other then that, the specifications of the 747-400F and the 747-400ERF with the higher MZFW option appear to be identical. The range for both is listed as 2,815 nm, the MZFW for both is listed as 635,000 lb and the MTOW for both is listed as 811,000 lb.

Does this mean the advantage of the 747-400ERF over the 747-400F is pretty much only if the higher MZFW option is not selected? Makes you wonder why it is offered on the 747-400ERF to begin with.

Any feedback would be greatly appreciated.

Topic: RE: Max Payload On 747-400ERF Lower Than On 747-400F?
Username: 744rules
Posted 2006-10-22 11:09:26 and read 7777 times.

don't know about the -400erf, but when you have the increased zfw on the -400 ( between 276000 and 288000) you're max tow is decreased. This means it's either max range or max payload.

Topic: RE: Max Payload On 747-400ERF Lower Than On 747-400F?
Username: PolymerPlane
Posted 2006-10-23 03:07:39 and read 7737 times.

I am not an expert, but IIRC, The difference between 744ERF and 744F is basically increase in MTOW and additional fuel tanks. I think this modification makes the 744ERF has slightly higher OEW. For the optional MZFW, the MTOW is basically limited to the same weight. Thus, your structural payload is lower on ERF.

BTW I still can't understand why any company would buy 744ERF with the optional MZFW. You basically do not need higher OEW from additional fuel tanks and structural modifications, since your maximum range is only 2800 nm anyway, and you don't use the higher TOW on 744ERF.

Cheers,
PP

Topic: RE: Max Payload On 747-400ERF Lower Than On 747-400F?
Username: RJ111
Posted 2006-10-23 13:33:09 and read 7704 times.

The 744ERF has the same max payload 112t or 123t (optional) as the 744F. Just it has a higher takeoff weight thus can fill up the tanks more when that payload is added. The tanks are the same size as the 744F and 744, but fuel is weight restriced at the top payloads.

Quoting 744rules (Reply 1):
don't know about the -400erf, but when you have the increased zfw on the -400 ( between 276000 and 288000) you're max tow is decreased. This means it's either max range or max payload.

The MTOW isn't decreased - it's increased. Compared to the 112t MSP version the max useable fuel capacity is +10t and the MZFW is increased +11t but the MTOW is only inceased +9t. So the MTOW is the limiting factor depending how far you're flying it. But then again, MTOW is always the limiting factor, just seems to be more pronounced on the 123t version. These are all paper ratings though.

At least that's how i understand it.   

Source http://www.boeing.com/commercial/airports/acaps/7474sec2.pdf

[Edited 2006-10-23 13:40:41]

Topic: RE: Max Payload On 747-400ERF Lower Than On 747-400F?
Username: 747Loadmaster
Posted 2006-10-23 16:45:01 and read 7679 times.

Quoting 744rules (Reply 1):
don't know about the -400erf, but when you have the increased zfw on the -400 ( between 276000 and 288000) you're max tow is decreased. This means it's either max range or max payload.

That is correct, if you use increased ZFW, MTW comes down.
I will post the exact amount tomorrow


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