Boeing 747 LCF Test Program

[smokejumper]

Sorry Smokejumper, I do not agree that range is not important.

An intermediate stop will have an enormous impact on costs and availability. It isnt the one hour re-fuelling time, its letdown, air traffic issues, and take off delays is likely to add 3-4 hours to projected trip time, and that could intoduce crew duty hours issues, and loss of almost one day per week of productivity.

Cheers
Achace

Range is aways an issue, but its importance should not be overrated. A loss of 5 or 6 hours (for letdown, ATC, landing, refueling, take-off, etc.) should not cause any great problems since Boeing undoubtedly will factor this into production schedules.

It would obviously be better to not need an additional refueling, but Boeing would be foolish to apply Just-in-Time delivery (in the literal sense)! True, crew costs could increase and may require an additonal crew, but that would not affect production. What could affect parts delivery (and hence production) would be a situation whereby the extra time required for unplanned refueling would reduce the number of flights the planes can make in a given timeframe.

If I were Boeing, I would be more concerned about the loss of one of the planes (crashes do occur) and whether the remaining 2 Dreamlifters could continue with the schedule, especially if an additional fuel stop is required.

[achace]

Doing the test flying from Edwards obviously suggests some modifications are likely, and it is safer to test from the desert than over a populated area(just in case).

The old saying "If it looks right it will fly right" is pretty accurate.

I will stick my neck out and suggest that we will see the Dreamlifter fitted with a new tail configuration similar to the 747/Space Shuttle with end plates on the horizontal stabilizers.

My suspicion is that yaw control in engine-out conditions is one of the problems, and the additional control of the shuttle 747 configuration could fix it.

Still not sure about the range though.

Cheers
Achace

[smokejumper]

Achace:

I had not thought about a 747/Space Shuttle tail configuration, but that may be a solution. Certainly the large area of the revised fuselage distorts the airflow and may "blank out" the tail surfaces by disrupting airflow.

What mystifies me is that the wind-tunnel tests apparently did not indicate a problem; perhaps the Boeing team misjudged the complexity of the issues under all circumstances.

[Ruscoe]

One of the things that has surprised me about this program, is what seems to be a very short period of time between first flight and entry into service, for such a heavily modified craft.
Even something like the 739ER which has no major changes apart from length, has taken months of testing.

If there is a problem I would expect it to be more along the lines of failing to foresee that the FAA or ? another body might expect some very extensive testing before certification.

Also with regard to a replacement aircraft I don't know if there is one. The 124 fuselage is not high enough, but I do not know about the Beluga or C5.

Boeing have said previously that only 2 LCF's are required, under normal circunstances but a third will provide backup for servicing etc.

I would guess the fall back position would be to transport by sea. This would inevitabley result in initial delays but should eventually be able to catch up.

How long does the slow boat from Japan and Italy take?

Ruscoe

[achace]

Rusco's comment is right on.

The Dreamlifter is not a 747. It is a very significant derivative with totally different aerodynamic and mechanical characteristics such as the winglet induced vibration, and undoubtedly this is part of the problem. Not much feedback from FAA or Boeing on what the problems are, but just maybe the Dreamlifter is a bit of a nightmare!

Remember the BAe Nimrod was originally a Comet airliner, but is barely reckognizable these days, and does not fly like one either.

Sea freight introduces big problems as some assembly sites are well inland.

Interesting times.

Cheers
Achace

[RC20]

I think it depends on what category and approvals they have it flying under.

They have had it moving aircraft sections already, so they have some kind of wavier. Maybe even under experimental category, and maybe some limited approval type even when in service. So, under restrictions, they may be able to use it until problems fully resolved.

I agree they must have run into an issue with the unusual attitudes portion of the tests. It may be the computer models just do not work in that area with a shape they have never been able to baseline and get the errors out of the program.

I doubt any unforeseen FAA requirements, they would have those ironed out before they even started. They have done these conversion types before, and the path I would think would be known.

Its flown well enough so far. The increase tail fin would be a clue that they at least had yaw control issues, and it may not have been enough for some situations.

If it becomes critical, I suspect they will get a waiver while they come up with a fix, then do one at a time. As long as they can keep one going, for now ok with the low rates, and two even at the anticipated initial full rte.

It will be an interesting story when it comes out.

Sea delivery is????? First you would have to modify a ship, then get it form dock to assembly plant. Section 41 is made in Kansas, so that would require a different solution. I don’t think even the C5 or Antonov 124 have that kind of circular section, but not sure if their box is wide enough to insert something like that.

Boeing probably has fallback, but it would not be good.

[DFW]

I once worked for a company that made large filament wound composite fuel tanks for rockets. We looked at the different methods for transporting these composite tanks, which were even wider than the 787 sections. Naturally, a modified 747 was not an option we looked at because of cost. The conclusion was that overland transport was not practical, and we would have to build our composite tanks next to a seaport.

One reason overland transport was deemed not impractical was the following (and it's something that embarrasses me as an American). Do you know what is the leading repair issue for the Goodyear Blimp dirigible? BULLET HOLES. Apparently, every so often someone takes a shot at the Goodyear Blimp just to see what would happen. That's very sick. Since hearing that fact, I've wondered if Boeing has this problem since it transports 737 sections by rail. Anyways, holes in aluminum are easy to plug. Holes in wound barrels are more difficult to repair.

So you can see why the Dreamlifter is vital for the 787 program.

[smokejumper]

My son, who works for Boeing in Wichita, tells me that very little damage is experienced in the 1500 mile (2500 km.) rail trip to Renton. It seems that most damage experienced has been from rail accidents, not vandalism. Once a tree fell toward the tracks and punched a hole in the fuselage of a 737.