Hushabye (oz8769)

About this Plan

Hushabye. Radio control model for electric power.

Quote: "Everybody's talking about trying electric power to solve the noise problem. John Fletcher brings you this neat sport design: 51in wingspan for Cyclone-15 motor and 3 function radio.

THE seemingly inevitable noise, mess and running expenses that accompany the average power model have had a considerable influence on my modelling career, and have resulted in my becoming a confirmed glider man. Therefore, when a model emerged from my workshop with a propeller on the front, my family regarded it with horror, and as yet another sign of my rapidly advancing senility! After they had experienced for themselves, however, the pleasures of electric power, the new model rapidly became accepted and, after the choosing of a suitable name (does anyone with a family ever get away without naming a model, by the way?), it has become just another of Daddy's models.

Background: When I decided to try my hand at electric powered flight, there were two early decisions to be made.

1. What approach to take? A powered glider with a geared-down motor, a la Mosquito (oz8460), or a direct drive motor in a normal 'power plane' layout.
2. Which power unit to use?

The recent introducticn of a range of power units onto the market gives a fairly wide choice and I decided to use one of the Ripmax 'Cyclone-x 5' outfits. Any electric motor of approximately the same size (35mm dia) could be used however, and the battery compartment will take either a 600mA or 1200mA power packs.

With a total power unit weight of 21 oz and a typical radio installation, using 3 servos and 225 nicad, weighing about 9 oz, it rapidly became obvious that, if I didn't want to end up with an excessively high wing loading, the airframe weight should not exceed about 1 lb and, with this firmly in my mind, Hushabye took shape.

A couple of ounces could be saved on the radio installation by dispensing with the motor on/off control but, in view of the damage which can be caused to the battery cells by over-discharging, I would recommend that the third servo is used. It also makes landing much easier!

With a wing area of 2.7 sq ft, the design wing loading was 16 to 17 oz/ sq ft and this, with the flat-bottom wing section used, has proved quite
acceptable. The structure, whilst being as light as possible, is quite strong enough and will stand the occasional bump on landing - and you must admit that it does look prettier than some other electric-powered models you may have seen!

CONSTRUCTION This is conventional, but keep an eye on wood weight to ensure reasonable performance.

Wings: Start by making the ribs by the sandwich method, using the root and tip sections shown, then build up the spars, ribs, leading edge and trailing edge fiat on the plan. Fit the spar webs from W2 outwards and, when dry, remove from the board and shape the leading edge ready to receive the sheeting. Pin the structure back onto the board and fit the sheeting to the leading edge and wing root. Leave it on the board for a good 12 hours before removing, to fit and shape the wingtip blocks and undersurface sheeting..."

Hushabye, Radio Modeller, February 1976.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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