# Introduction

Set 10261 is a roller coaster. It has 4123 parts which is respectable but not the highest number in available sets. There are a few new parts in it such as the red coaster rails (though some occur in older sets) and the cars.

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Set 10261 is a roller coaster. It has 4123 parts which is respectable but not the highest number in available sets. There are a few new parts in it such as the red coaster rails (though some occur in older sets) and the cars.

The support pilons are connected with bracing struts on four levels.

Mostly the braces are horizontal and along the knob axes, but some are at angles, and hence must be hypothenusae of Pythagorean triangles.

To the designers' credit, all these are indeed correct and employ no special parts.

There are 9 different cases of those. Using the page numbers of the Lego building guides [1] and [2]:

(occurs eight times — [1] pages 37, 39, 71, 73, 104, 106, 129, 131)

Its effective length is 14.5 units (14.5×8=116mm) and it connects a ball on one side to a pilon cylinder, using a hinge brick, on the other side. The effective points are 10.5 and 10 units apart.

(occurs twice — [1] page 93)

(occurse twice — [1] page 137)

Its effective length is 15 studs so we suspect a 3-4-5 case expressed as 9-12-15 and indeed horizontally there are 9 studs and vertically there are 3 round plates and 9 round bricks or 10×9.6/8 = 12 stud lengths.

(occurs once — [1] page 152)

This consists of two hypotenuses of length 10 with no vertical struts and no horizontal brace.

It is a double case of 3-4-5 expressed as 6-8-10.

(occurs once — page [2] 154)

(occurs twice — page [2] 169)

(occurs twice — [2] pages 180, 182)

(occurs once — [2] page 197)

(occurs three times — [2] page 199)

For me this is the most ingenious one: it has an additional middle support!

Only the relevant parts are shown, the actual struts are thicker, if only to keep the parts linked. The unit in this diagram is the 8mm stud space.

Note how in two cases the actual horizontal connections occur at a height different from the sides of the triangles by insertion of a few layers of plates.

The carriage drives at the top aft has a double universal joint axle at 45º

The main drive on the ground has a doulbe universal joint axle page [2] 118.

the handrails on the steps are at …?

The chain drive has length …?

supports strange? p. 168