Sig Riser 100

Willie Findlay

Having lost my Algebra and crashed my Sigma in quick succession I was left looking for a replacement sailplane that I could use off slope and winch and after much trawling of the net I decided to go for the Riser 100 kit. This Sig kit was drawn to me by its specification, cost, but more importantly its claim to be easy to build.

Once it arrived a delve into the box revealed full size plans on two sheets, various shapes and sizes of balsa wood, CNC cut lite ply fuselage parts, a hardware pack and a very comprehensive step by step build book with pictures. A parts list is at the back of the book and is well worth visiting at the outset to identify and mark all pieces as some parts are almost identical, but wrong placement causes problems later on as you will find out.

There are two decisions that need to be made in the build, namely whether to include wing spoilers and whether to go for a bolt on or rubber band wing fixing, although you have some time to think about this as you proceed. I decided to include the spoilers and bolt on my wings.

Starting with the fus, the CNC lite ply parts need popping out and deburring before being dry fit and bound with rubber bands ready for application of some CA to the joints. I used a combination of medium and thin CA for most of the build. I attached the nose block and cover with Titebond wood glue which I have found to be quite strong.

The wings are polyhedral and built in four sections combined into two halves. The two inboard wing root ribs are lite ply whilst the others are balsa. Leading edge is a spruce dowel and the trailing edge is preshaped balsa. Having prepared the ribs, the spruce spars are secured to them with CA. A dihedral gauge is used to ensure the root ribs are set at the correct angle before gluing. The outboard wing sections are constructed in the same manner but the polyhedral gauge is us to set the root rib angle here. The wing tip is a solid balsa block for which I again used the Titebond glue.

In the case of wingtips and nose block I sketched the desired outline on the block before rough shaping in the band saw and finishing with razor plane and sandpaper.

Before joining the wing sections together, the inboard sections were prepared for the spoilers cutting out the centre ribs and putting in the reinforcement and tubes for the Dacron chord. The wings are then epoxied together keeping the angles in place by whatever means. A brass tube is inserted in the inboard section to locate the steel wing joiner.

The tail feathers are open lattice design and control surfaces are attached with cyano hinges with epoxy used to attach to the fus. The wing bolt seatings in the wing require beefing up as you might expect and the supplied snakes are fitted into the fuselage and expoxied strategically.

Covering is not supplied in the kit and I used three rolls of Solarspan to complete this task. The fact I only had three rolls dictated my final colour scheme if you can call it that.

Three standard servos were installed for rudder, elevator and spoilers and 6oz of lead placed in beside the battery in the nose to achieve the correct CG.

The maiden flight took place on the Cairn in a 10mph wind and the Riser proved to live up to its name quickly gaining height. Minimal trimming was required and it was gentle in the turn. It looped safely and spun comfortably even though it still appeared to be going up!

Off the winch I was a bit apprehensive about the wings staying put, but even on the windy day of the BBQ, it went up okay and came down okay albeit it struggled to penetrate the wind once off the line.

From start to finish the Riser took two weeks of stop start building to complete and was relatively straightforward. A mistake I made related to the lite play wing ribs which are very similar in appearance but do not have any identifying markings on them. A hole is bored through them at a certain angle to house the brass tube for the wing joiner and maintain the dihedral. As I managed to put them in any old order messing up the angles, I needed to oversize the holes and pack around the tube to get the correct dihedral.

The book suggests trimming the outer snake flush with the fus, but this leaves a long distance to the control horn and the inner snake is liable to flex. I used a cable clip to prevent this. Either extend the outer snake length or use a small portion to glue to the tail plane.

I'm very pleased with the end result as you can see and look forward to flying it on the warm thermally days. My early experience with the model is that it is a Riser by name, Riser by nature. Roll on next summer.