Henk de Jong's Mustang Ace

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Henk de Jong's name appeared decades ago in “Aeromodeller” magazine thanks to his achievements in international control line stunt competitions. He has remained at the top ever since..

Like many line control experts, Henk not only builds but also designs his own machines. Seeing his basic trainer design fly so well I wanted to build one myself and that is what this web page is about.

It all starts with a working example of the plan, in my case scanned A4-sized segments printed out and stuck together. If you do this, check for accuracy! Ordering 2 copies of the original is the smart method.

Being a recycling enthusiast I often find myself improvising instead of buying. The beech engine bearers had already seen years of service as drawer rails in a IKEA cupboard. Existing holes are lined up with those required on the plan ( to be used for mounting the undercarriage).

Below are an exploded view of the fuselage and how the core comes together. The recycled beech bearers, slightly too thin, are brought up to spec with a plywood shim.

The building instructions recommend slow epoxy for the fuselage assembly. My 30-minute expoxy hardened too quickly because of hot weather and the job became stressful as time ran out. Applying resin to one surface and hardener to the other – the procedure used in laminating sailboat hulls – is probably an option. A simpler solution is white glue or aliphatic, but prepare the clamping carefully to make sure that nothing shifts as pressure is applied.

The picture shows lots of elastic bands meant to hold the lamination together while the epoxy hardens. We hope that the pressure was applied on time...

The wing spars are balsa/pine laminations.

The wing on the building board. It is a very simple assembly but a hell of a lot of wood and adhesives for someone used to building small rubber-powered models.

One of my favorite and most effective tools is the small David plane. Fit a new blade and Bob's your uncle.

The vertical tail is supposed to be sawn out of 2 mm ply but none was at hand and so we improvised again: thinner plywood and two scrap balsa laminations. The result is stiff and even allows for a bit of profile sanding. Sunny weather assusts.

Hidden in the heart of the wing and fuselage is the bellcrank that translates the operator's hand movement into the required up/down elevator change. In addition to that important role, the bellcrank takes the centrifugal force load imposed by the circling model. Any quality issue in it's construction will remain hidden until the time that things have gone wrong. Hinge points that bear loads are all strengthened with brass tubing (epoxied into the dural crank). Music wire leadouts are carefully bent and soldered with brass windings.

Simple control line models have all the mechanics fitted externally, but in the case of this more refined design, the control mechanism is located internally. 1 mm spring wire leadouts run from the bellcrank to the wingtip where the flying wires can be attached. On top of the wing centre section, the pushrod for the elevator emerges.

Tissue is unsuitable for covering heavier models and as I dislike plastic foils, SIG “Koverall” was chosen. This nylon-type woven material handles like tissue but is much stronger. Be aware of the very fine dust that results when cutting the material with scissors! Other than that, a useful product that goes on like paper and can be taughtened simply using a hairdryer or heat gun.

I treated the wooden frame with sanding sealer and dope first and then later brushed thinners through the covering material to stick it to the framework. After the shrinking process 2 thinned layers of dope were brushed on and finally the model sprayed with automotive acrylic lacquer.

The slot in the fuselage where the wing slides in was accomplished carefully and slowly.

Warm and dry weather assisted greatly in meeting the deadline of 13 September. Hours had to be spent on the flying field to get the engine running, but eventually it was Mr. Gerben Wassenaar who understood that you need to flip a Super Tigre G20 diesel's prop backwards in order to get it to run forwards, and that the engine also likes short fuel lines. Oh well, the Mustang Ace flew and now we can relax and make the finishing touches.

Do you want to build a Henk de Jong model? See (Dutch language) info at :


On a windy June day pilot error led to taking off into the wind and completely losing line tension. The model made a circuit in front of me instead of around and cartwheeled into the ground. A few days later the repair work commenced. The severed fuselage sandwiched between two pieces of 2 mm ply.

The joint has now been covered with a “Koverall” patch that in turn has been treated with sanding sealer, dope and lots of sanding. The elevator is held in place with a clamp while new hinges are doped on.

Resprayed with expensive automotive acrylic (the silver) and black and white acrylic sold by Action-stores (very much cheaper). The faded insignia sticker (inkjet printer) was refreshed with Humbrol, The fuselage markings are home made transfers.