HL-2 (oz15851)

About this Plan

HL-2. Radio control scale model for electric power with geared 400 motor. Wingspan 44.5 in.

Quote: "Free Plan. HL-2, by Peter Rake. A very simple sport scale model intended for a geared 400 motor and three function control. Prototype model built and test flown by Istvan Noszvai from Germany.

For those of you wondering how a model designed by an Englishman came to be test built by a Hungarian engineer living in Germany, the answer is very simple. I posted a list of the designs I intended to draw up for this year an the E-Zone electric flight website. At the same time, I said that should anyone wish to try any of them out they would be most welcome. Istvan (Steve), helpful chap that he is, was kind enough to volunteer for one of the 400 size models, the HL-2 was what he ended up with.

In case you have never heard of the HL-2, she is a Polish aircraft designed in the nineteen twenties (l think). i can't be more precise than that because at the time of writing I've managed to misplace my reference material. What I do know is that she wasn't actually that successful because the originally intended engine wasn't available and she was forced to use a smaller one. She did fly, and quite well really, but was underpowered. However, her simple, but attractive lines do mean that she will make an ideal introduction to the ioys of electric powered scale models. Although her lightweight structure means that she isn't an ideal first model, she would make a very acceptable second model, once you have learned the basics of flying on one of the many cheap foam models available. Whilst her structure is all very basic and straight forward, it is possible to add enough scale detail to make for an interesting little model.

Equipment and installation: I always like to start with this section of the construction article because it becomes so much easier to build the model if you already have all the equipment to hand.

Because of the shape of the nose on this model, I assumed that the only really viable motor type is one with an in line gearbox fitted, Istvan has proven me wrong by fitting a 2.33:1, off set gearbox. However a cheaper, though less scale-like, solution would be to leave the bottom of the nose block open and use the excellent GWS 300C motor unit.

For the purposes of this article, and because it is what I planned to be used, we'll only focus on the in-line set up. Any in-line (planetary) gearbox of between 3:1 and 4:1 may be used in conjunction with a 6 volt 400 motor, and this is fitted to a rolled ply tube through F1. Power should come from a 7 or 8-cell pack of 500AR or 600AE Ni-Cads, or an 8 cell pack of 800 mAh NiMHs. Istvan powers his model with a 7-cell pack of 500 AR cells, but higher ratio gearboxes may require the extra cell. Once the weight of the pack has been used to help balance the model, it should either be permanently fixed with a small amount of silicone sealer, or as Istvan has done, make it a tight fit into a battery box.

Control functions for our model are provided by either a mini or micro receiver, a 15-20 amp rated speed controller and two mini servos. Whilst the receiver and ESC should be fitted to the sheet fuselage sides with servo tape, the servos are screwed to spruce rails in the usual manner. Linkages are via pushrods, which may be nothing more than 1/8 in dowel with 20 swg wire ends bound and glued in place. A simple Z-bend at each end allows for simple, lightweight connection to both servo and control horn.

Wings: Since the wings are one of the simplest parts of the model, except for cutting out the ribs, that seems as good a place as any to begin building. Once you have all the ribs cut, noting that the end ribs (root and tip) are 3/16 balsa, trim the root ribs to suit the cut out at the centre section. Pin down, over the plan, the leading edge, spar and trailing edge and add the piece of block balsa at the cut out. Glue all ribs in position, with the root ribs angled in slightly to allow for dihedral. All remaining ribs are upright. Add the 1/8 x 3/8 pieces into which the strut ends will fit, and allow to dry thoroughly. Repeat for the opposite wing panel.

NOTE, if bass is not available in your area, spruce may be used. It will however be heavier.

Trim the block balsa to follow the line of the wing ribs, trim and sand the panels overall and notch the positions into which the centre section struts will be glued. It is important to do this now, do not wait until after the wings are joined because it is virtually impossible to drill into a glue joint accurately - the drill will run off into the softer balsa rib. Cut the slots for the ply dihedral braces and join the wing panels, taking care NOT to fill those notches with glue. The braces are just simple rectangles of ply, all excess material being trimmed and sanded away after the wings are joined..."

Direct submission to Outerzone.

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