Stupid 747 Question.

[goodgig]

Eh. nevermind.

Really.http://www.youtube.com/watch?v=fTe8VDB40WA

 

[LR25]

Its an 18 wheeler.

 

[B737Dvr]

has 5 engines.

 

[Bob_Sacamano]

I've always heard the only stupid question is the one you don't ask...

 

[MED]

394.6 tonnes MTOW
385.7 tonnes MLW

 

[B-atch]

The 747-4000 freighter is 396,893 KGS MTOW and 302.092 MLDW....

 

[CaptSeth]

What's the pay and QOL?

 

[B-atch]

A slight improvement, but a looong ways from were it should be!!!

 

[Boeing747Driver]

A slight improvement, but a looong ways from were it should be!!!

But you are a galley babe:beer:

 

[B-atch]

You know it Bigg Boy!!........Are you ever going to afford a REAL sports car??? LMAO!!!

 

[Boeing747Driver]

You know it Bigg Boy!!........Are you ever going to afford a REAL sports car??? LMAO!!!

Here is that real sports car in action on a bad night.
http://www.highperformancestangs.com/forums/showpost.php?p=18843&postcount=1

 

[B737Dvr]

ok, here is a legitimate question that I have had for a while now and I haven't been able to get an answer for.

I heard that Cathay has a procedure that allows them to increase the max takeoff takeoff weight for a particular takeoff by using reduced (flex) power.
This is intuitively contradictory, but was told by one of their captains during an interview a while back ago that they indeed can do this!

How does reducing power increase the max takeoff weight for a particular takeoff?

 

[Secret Squirrel]

If it is too heavy the engines will rip right off the airplane when you spool up for T/O. If you use a reduced thrust it eliminates this possibility.

 

[B737Dvr]

say what?

Uhhhhhh, I dont consider myself to be the smartest....or dumbest....but......HUH???

Need more INPUT!!!!!!!!

INPUT!


ps. and oh btw, when you or anyone else answers this questions please include information on how this works out with regards to performance and runway analysis charts!

ie. higher V-speeds on climbout are shown by data to provide more lift during a critical time (like 2nd-segment). If you are climb limited and have room to spare runway-wise, then increasing speeds will allow you to takeoff at a higher weight, where you would otherwise be limited by climb criteria.


an explanation along these lines would shed some light on my "how do they do that"? question.

thanks!

 

[Bjammin]

If it is too heavy the engines will rip right off the airplane when you spool up for T/O. If you use a reduced thrust it eliminates this possibility.

What!!!??

When at MAX TOW we use MAX thrust most of the time. You reduce power when at light weight to preserve the engine life and it can reduce your VMCG on a wet runway thus reducing your V1.

This second instance is most likely what the guy was talking about.

Make sense?

 

[B-atch]

ok, here is a legitimate question that I have had for a while now and I haven't been able to get an answer for.

I heard that Cathay has a procedure that allows them to increase the max takeoff takeoff weight for a particular takeoff by using reduced (flex) power.
This is intuitively contradictory, but was told by one of their captains during an interview a while back ago that they indeed can do this!

How does reducing power increase the max takeoff weight for a particular takeoff?

Are you sure its MTOW?.... The 747-400 freighter (SOME MODELS), does have a ZFW that can be increased under certain conditions.

 

[B737Dvr]

bjammin

I take it you fly for Cathay. Well one of your 744 Captains told me that during an interview last year but I still can't quite put it together. Your explanation makes sense, but somehow to me at least it isn't relevant. I fly -100/200's. For some repo flights we take off with just enough fuel to get there plus reserves, so that brings us to very light TOW's of around 400-420K. In those cases our V1 does come close to Vmcg and the lowest V1 on the 100 is 113kts, and 115kts for the -200. I don't know about the -400 but I cant imagine it being too far from that. Now at heavy weight takeoff's our V1 speeds are above 150kts. Since Vmcg is dependant on engine thrust and thrust varies with altitude and temperature, I can follow your train of thought on reducing Vmcg and thus allowing for a reduction of V1, however at heavy weight takeoff's there is a huge difference between the two and that is why I don't think the reduction in Vmcg is relevant.

Is this reduction in thrust for takeoff specifically addressed anywhere in your performance section on how it allows for greater TOW's?

thanks!

 

[B737Dvr]

Are you sure its MTOW?.... The 747-400 freighter (SOME MODELS), does have a ZFW that can be increased under certain conditions.

Yeah i am sure it is MTOW, because i was getting grilled on everything affecting max TOW and going over theory on reduced thrust, increased v speed usage and CG shiftage. The only gotcha was relating to this Reduced power/increased TOW factor.....

 

[Bjammin]

B737Dvr,

The aircraft can be Vmcg limited at very low weights on a wet or icy runway. We run into this in ANC going to North America during the winter.

The ACARS does all the calulations for us, but it easy
to see when Vmcg = V1.

I'm sure the 777 runs into this all the time.

I cannot think of a case or even the theory behind reduceing power to increase weight, but sometimes reducing power is the only way you can become legal to takeoff as stated above.

 

[B737Dvr]

Bjammin,
I agree with you on the Vmcg issues at low weights especially on other than dry runways....i have run into that as well. However the other issue still eludes me. I have asked around and have not gotten an answer to that.....oh well the search goes on....

thanks anyways!