747 dihedral?

[wombat]

Hi all, I’m still wrestling with the Revell 747-400, in which no two parts join without industrial quantities of filler. Does anyone know the correct dihedral angle of the wings and tail planes? The parts are capable of joining in a wide range of possible angles...

 

thanks all

[neilg]

On Jane's All the World's Aircraft, it gives this figure about the dihedral:

 

Dihedral at rest 7°

 

The full information about the wings is this:

 

Sweepback at quarter-chord 37° 3'; thickness/chord ratio 13.44 per cent inboard, 7.8 per cent at mid-span, 8 per cent outboard; dihedral at rest 7°; incidence 2°; winglets, canted 22° outward and swept 60°

 

http://janes.migavia.com/usa/boeing/boeing-747-400.html

[TheyJammedKenny!]

If I were you, I'd measure the dihedral along the trailing edge of the wing.  If it's like the 707, the 747's wing has constant dihedral on the underside, but expands as it meets the fuselage on the topside, leaving little dihedral along the wing-body join.  

[Space Ranger]

According to Boeing's "747-400 Airplane Characteristics for Airport Planning," dated December 2002, the vertical clearance from ground to the tops of the winglets, based on loading, can range from 22 ft 0 in to 24 ft 0 in. In 1/144 scale this would be a range of 1.833 in to 2.000 in. Clearance from ground to bottom of wingtip can range from 16 ft 9 in to 18 ft 9 in, or 1.395 in to 1.5625 in.

 

Vertical clearance at the tip of the tailplanes can range from 27 ft 6 in to 29 ft 9 in, or 2.292 in to 2.479 in in 1/144 scale.

 

Note: You can download copies of these airport planning documents in PDF format for all of Boeing's jetliners, as well as McDonnell-Douglas jet transports, here: https://www.boeing.com/commercial/airports/plan_manuals.page

These are very handy for assisting with accurate assembly of airliner models.

Edited October 25, 2020 by Space Ranger

[71chally]

I always find the 747 dihedral 'at rest' figure a little hard to quantify.

If you look headlong at a 747 wing while it's on the ground, the wing appears to be one dihedral value from the wing root to say the inner engine, and then a lesser dihedral from there out to the wing tip, even when empty.

I've often wondered if the 7 degs is an average through the whole wing, or the inner wing only when at rest? 

Obviously fuel loads and in flight changes the outer wing dihedral.

 

The other oddity that I've rarely seen mentioned is what happens with the wing extension, just inboard of the winglets. From the front it looks like a natural extension, but from the rear appears as another slight dihedral change, almost like the wing section washes out in the region.