Erco Ercoupe


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A kit by Thomas Designs with Comet-roots..

Detailed plans, excellent wood, all parts laser-cut (an amazing first-time experience!)

Going back in time a bit, here is how the fuselage started life...

My nose block differs vastly from the drawing because ballast will be required anyway and if weight is to be added it might as well be made useful. A rubber-powered model's nose takes a lot of punishment during handling (and crashing) and extra strength is welcome. Three bamboo dowels locate in a thin ply former.

Here the various parts of the undercarriage wheels are taken from the balsa sheet with an ease that the builders of Comet models in the 50's could only have dreamed of.

The laser-cut wheel segments are lined up on a aluminium tube, glued and sanded to shape.

Another deviation from the original is the tongue-in-box attachment of the wings - hopefully the weight penalty will be rewarded with less damage to leading edges should they hit obstacles.

The boxes are integrated into the original wing construction.

After an extended interruption in order to do some other builds, the Ercoupe started to get attention again. The timeout helped to decide the canopy construction – I did not choose to mold a one-piece bubble but used the 3 transparent laser-cut segments supplied in the kit. The fit proved to be excellent but the assembly sequence a challenge.

Tissue: where there are lots of corners to take, I like to dampen the tissue before placing it on the structure. Fixing is achieved by running thin wallpaper paste on the structure first but an alternative is to dope the structure in advance and later run thinners through the damp tissue.

Do not attempt to cover large area's with one piece of tissue if there is multiple curvature at large, for example at the wing tips. It is preferable to deal with such areas in smaller segments.

Deviation from the plan (knock-off wings) meant undercarriage changes as well. All three legs have shock-absorbing characteristics that will hopefully save the structure when the going gets tough.

The wing fillets are another laser-cut item in the box. I always argue with fillets and again on this model did not succeed in applying them without using a lot of paper and adhesives.

All the bits shown weigh in at almost 40 grams. That may look rather heavy but the beefed-up nose and tricycle undercarriage will alleviate the need for ballast.



Tail plane (stabilizer) and fin(s) are very important items on rubber-driven model aircraft. Often these items are relatively heavy, necessitating nose ballast as compensation. Light construction, when achieved, is prone to warping and/or damage while making trimming adjustments. In the case of the Ercoupe, traditional construction is maintained for the twin fins, but the stabilizer is made of thin foam with a balsa spar. The foam is lightly sanded and smeared with diluted white glue in order to obtain a smooth finish that can withstand the later spray painting process. More importantly, the foam tail plane will never warp and is easy to adjust by careful bending.


A piece of thinly-sliced ceiling tile foam is prepared by light sanding and the application of thinned white glue.


The Ercoupe is ready for it's paint job which will probably be a silver one, but first the fin mounting will need revision because they break off too easily.


The Ercoupe is prepared for it's initial flight, 4½ years after building commenced. The only adjustment needed to the flying surfaces was “up” elevator.

The kit contains a few small decals and a template for the main registration number. Old-fashioned gummed paper tape was used as a basis for home made transfers. The gummed side of the tape is given a coat of clear dope that is mixed with a few drops of castor oil as a plasticizer, allowed to dry and then followed by paint. The template can be used to cut through or trace with – both methods are depicted below. The black outline is plain patience – I do not know of any tricks here.



Below, the number 6 has just been cut from the tape. It consists of brown paper, a water-soluble glue layer, dope/castor oil layer and a paint layer. Once dipped in water and left to rest a while, the dope/paint layer can be slid off the paper and onto the model.

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One number left to go! Without the castor oil in the dope layer, the transfers would be brittle and almost too delicate to handle – the castor oil additive is the secret to success.

Without the black outline the registration would be rather dull – it was worth the effort.


Interscale 2015.



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