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This will make your eyes water


Graham

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The "fault" is not the overall dihedral, but the angle of the kink. This will not change with loading. A wing is actually a pretty solid structure, with rigid fittings at major joints such as the fuselage or inner/outer wing joints. Loading will bend the wing, but it will bend it into a curve, not noticeably change the structurally-set angle at a given point. If you think about this, reducing the angle at a given point would require a significant gap opening between panels at the top of the wing, or significant crushing at the bottom.

I gather the Lancaster manual states that this kink is 7 degs, and the the Revell kit is less than this: 5 degs? If this is true, then there is no way that the kit is correct, under any loading condition.

If you are happy with the wing then leave it, but don't change it just to reflect different loading cases. What changes is not the angle at the major joints, but the overall flatness/curve of the wing as seen head-on. This will differ in the flying/static cases. When flying there are upward forces on the wing, with downward forces from gravity acting on the fuselage and to a lesser extent from the engines. On the ground, the upward force comes from the undercarriage fixings, and the downard forces act both inboard and outboard of these. The wing will therefore have different bending modes in these two cases - but the kink will be 7 deg in both. If you wanted to demonstrate an extreme point by putting several tons onto the wingtip then the outer wing would curve downwards (and the fuselage move upwards) - but the kink would remain at 7 degs.

The model - any model - clearly cannot accurately reflect the curve of the wing in all loading cases, and will generally be built to match the manufacturing drawings. It may however match the shape of the aircraft under the loading at which measurements for the model were taken. If so, this will certainly be the static case not the flying! Because of the rigidity of the structure under 1g loads, this will be close to the design case, certainly with light loading.

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The seven degree figure is one I've seen quoted many times, but how is it measured, ie presumably along the main spar, but top or bottom surface, or along a measured central line between the two?

Cheers,

Bill.

Normal aviation engineering practice is to measure and declare dihedral along the centre of the airfoil at the point of maximum chordwise thickness, unless another measure is specified.

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Well I ordered my Hasegawa version for $93 Can, noticed an online retailer from the US charging $155 to $161 for the conversions!!! Yikes!

Ordered & received the CMR York conversion from the same retailer (Canada) and it needs the Hasegawa wings, now I've gone full circle as the B II conversion needs a Hasegawa fuse!!

Gawd I hate wasting Hasegawa kits.

Graham

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The seven degree figure is one I've seen quoted many times, but how is it measured, ie presumably along the main spar, but top or bottom surface, or along a measured central line between the two?

According to the manual it's on the datum line (and it was 7 +/- 15') and the datum point (I have no idea if that's the same thing) is shown as on the rear spar of the main plane, not far from the outer edge of the aileron. There was a second measurement, which was taken on top of the rear spar, which was 5 degrees 19' +/- 15'.

Edgar

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