Half A Twin (oz2905)

About this Plan

Half-A Twin. Twin engined control line model.

Quote: "Harold the Hot Pilot applies asymmetrical stability to the XF5F and comes up with a 2-engine semi-scale stunter that's a cinch to build and a dream to fly. Half A Twin, by Hal DeBolt.

It can be said that at one time or another almost every modeler has had the urge to build and fly a twin engine job - for twins are really different, fun to operate and draw attention the way honey draws flies. For most this desire has never been fulfilled, due to several good reasons; one main one: twin engine operation has been considered expensive, complicated by gadgets and usually involved a complex model if it were to be attractive. Nevertheless, the desire for one is still there.

The Half-A Twin is believed to be the model that will allow even the most skeptical diehard to realize said desire. With this design, we have tried to incorporate the answer to all the objectionable problems which have been present. The answer to the expense problem comes with the use of Half-A engines. Most of us have one or two on hand anyhow, and with the Twin they do not necessarily have to be of the same make or power, allowing even more leeway in powering it. The use of Half-A engines also solves the operation problem as these small jobs are noted for their easy starting and consistent running ability in the air.

In flying the model, it has been noted that you can hardly tell the difference between the effort required to operate the two engines and that required for single engine jobs. Then, too, the performance in the air has been really remarkable; no instance can be remembered when one engine failed without reason. It almost seems that if one engine is operating well it will pull the other through if you should happen to have a false setting!

To provide a bit of attractiveness while maintaining the simplest possible structure so as to keep the construction time down, we incorporated some of the lines of a really sensational airplane of a few years back. Remember the Grumman Skyrocket, the Navy's XF5F fighter? We obtained the simple structure by just following the outline where possible and even changing the looks in one place by doing away with the twin rudders that graced the original. As a result, the profile fuselage, simple pod nacelles and constant chord wing make for one of those satisfying single evening construction jobs.

The best way to describe the flying ability is to say it is a 'sport-stunt' model in performance. That is, if you are a beginner here is a model as easy to handle as any trainer you have ever flown. At the same time, it will perform all of the basic maneuvers with comparative ease. The control response is excellent, and if you are not too - particular about how tight you do your loops, eights, etc, you will find it does a mighty fine job. One of the secrets of its performance is the asymmetrical stability which does away with all wing weights, offsets, etc, which in turn allows for a really lightweight low-drag job of extremely high performance.

When it comes to building, we believe that you will find all the information necessary on the drawings, except perhaps for a few hints as to method. To start, it is best to get the big job out of the way, in this case the wing. Commence by notching the leading and trailing edges and lining them up with the ribs on your bench. After assembly, the bottom sheet covering is added; note that it extends to the naeelles on the lower side only. The controls are installed complete before adding the sheet to the top side.

Next step is to cut out the fuselage profile from quarter-inch sheet and, after shaping, installing it on the wing. The tail can then be added as shown and the controls hooked up to the elevator. They should work very freely.

The nacelles are made from block balsa and require but little carving. First, cut them to rough profile shape and fit them to the wing, making sure that the thrust line is neutral. Next, hollow them out at the front only so that the Darwin No2 style 'B' fuel tanks will slide tightly in place..."

Direct submission to Outerzone.

Quote: "Here is the Half a Twin from Air Trails issue 12-51. This is a cleaned-up, full size, plan scan from the treasure chest. Nice and small, both file size and model size".

Thanks to Fernando for help and the model pic.

Update 11/10/2022: Added article, thanks to RFJ.

Supplementary file notes

Article.

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