Horsa II (oz10073)

About this Plan

Horsa II. Free flight pylon contest power model. Originally powered with Ohlsson 23.

Quote: "AFTER a season's competition flying in 1947 1 decided in 1948 to design a pylon competition job of my own. Experience showed that such a model must be capable of a ratio of at least 10:1 and I am happy to say that this was achieved as subsequent test flights and competition successes proved. The model was only entered in two Rallies and obtained first and second places respectively in these; furthermore, in neither case was there any thermal catching.

The design was centred around an Ohlsson 23, a powerful and very reliable power unit and a cowling scheme inspired by a fellow clubman, Geoff Dunmore, was used. To obtain the performance in mind, weight had necessarily to be kept to a minimum in order to give a high power loading which in conjunction with generous wing area would give a low wing loading. No apology is given for adhering to the standard American pylon layout as it is obvious that this type offers the best angle of climb combined with maximum stability. The usual angularities of this type of design have however been smoothed out and an effort has been made to smooth out contours, consistent with good engine cooling and low frontal area. Although the original used an Ohlsson 23 with spark ignition, any 19 Glowplug engine or 2 - 3 cc diesel engine, providing it runs inverted, would be suitable.

Fuselage construction is based on Schulman's well known method using a sheet outline with sheet cemented to its sides at right angles. This is a simple yet sturdy method and a time saver in building.

Wing construction is also straight forward, the only special feature being the dural wing tubes. These should be filled with sand before bending to the required angle. (Empty out sand afterwards, of course!)

Trimming and flying follow the usual long established principles. Model should balance at the point indicated on the drawing, if not weight either at nose or tail until it is correct. First flights should be made on reduced power and the rudder adjusted to give a gentle left-hand circle. Any stalling or diving tendencies should be corrected by adjustment of the tailplane incidence. Maximum power should be approached very gradually through a number of flights, care being taken to avoid excess banking..."

Scan from DBHL, cleanup by theshadow.

ref DBHL-7576.

Direct submission to Outerzone.

Update 22/05/2018: added article, thanks to RFJ.

Supplementary file notes

Article.

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