MP 12 (oz13752)

About this Plan

MP 12. Free flight A/2 competition glider model. Wingspan 85-1/2 in.

Direct submission to Outerzone.

Quote: "Dear Mary, Attached is a scan of the Max Hacklinger M.P.12 Nordic A2 glider which I do not think is as yet in your wonderful collection of plans. It came from a rather ratty old dyeline print, but is quite usable 'as is' I think [Fixed now, done cleanup. See supplement raw scan for comparison]. Thank you both as ever for all the great work. Best Wishes,"

Update 11/4/2022: Added article, thanks to RFJ.

Quote: "An aristocrat among A/2 sailplanes, this design scored a five-maximum total to win first place in the 1954 German Team Trials. MP.12, by Max Hacklinger.

MP.12 is a Nordic Glider specifically developed for contest work, but not for fine weather flying only. Our experience with this type of model leads to the conclusion that it is entirely suitable for typical British weather, for its performance does not deterioriate with strong horizontal and vertical gusts. To achieve this, smaller aspect ratio and dihedralled wing-tips were preferred to Max's former still-air design, and particularly the tail moment arm was shortened, as this improves thermal longitudinal stability.

The still-air duration of MP.12 (still air obtained in a hall) is 27.5 ± 0.5 cm/sec or 180 to 185 seconds from a height of 50 metres, providing the wing is unwarped.

At first glance, the construction may seem complicated because it is unconventional. However, by carefully following the building sequence, the model can be built in quite a short time without trouble.

One point should be carefully noted. Stability in flight improves if we concentrate the whole weight around the centre of gravity, especially in relation to the distance from the lateral axis. 0.1 oz spared at the tail is far more valuable than 1 oz spared at the c/section!

The stick type fuselage consists of three hard balsa sheets glued together corner-wise with a hard drying cement. Pin sheets into position, and fill the open corners with cement until the illustrated section is achieved. This is most important, as these cement 'longerons' take up most of the torsion.

The wing tongue is steam bent into shape, taking hold of the tongue so that only the centre area is free, and the upswept parts are exactly flat. Dry the bent tongue over heat until set. Glue the tongue carefully into place on the fuselage seating block, adding root ribs and fairing later, when the complete wing can be offered up on the tongue.

Fin is slotted to take the tailplane tongue, this being excavated with a fine file as on the original, an alternative scheme being bent to laminate with a 1/16 centre core and two outer 3/32 layers. When all parts of the fuselage are installed, and not before, sand to shape.

Tailplane ribs are formed by block method, using root and tip rib templates. Build in two halves, slotting ribs into trailing edge, then adding leading edge. Remove from board and fit the main spar, finishing with top spar. T/E camber is bent in about five minutes after doping, ,when the balsa is softened. Note 3/32 in washout at the tips when laying in the diagonals..."

Supplementary file notes

Article.
Raw scan.

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