Heinkel He 18 (oz8840)

About this Plan

Heinkel HE 18. Free flight scale model for electric power.

Quote: "Designed for the HiLine Mini-6 geared electric motor running on three 100-mAh batteries, this clean-lined, all-wood Scale rendition of the between-the-wars Heinkel is simple enough to tempt the moderately experienced builder, yet so stable in the air that seasoned fliers may want one, too. Heinkel HE 18, by Hurst Bowers.

IN 1924, only six years after the 'war to end all wars,' there were rumblings within Germany to circumvent the sanctions imposed by the allies. These sanctions precluded the recreation of an aircraft industry.

One of the prime players in the rebirth of German aviation was Dr Ernst Heinkel, a brilliant professor and engineer. Heinkel developed a light, instructional plane which showed much promise by winning the Gothenburg competition in 1923. This was the basis for development of a much improved version, which emerged in 1924 as the Heinkel Model HE 18.

The innovations that were incorporated into the new model were truly awesome. They included full-span ailerons which could be deflected downward equally to serve as flaps while still maintaining full lateral control. The engine mount was hinged so as to pivot 90° to the left, fully exposing the accessory section for ease of maintenance.

The wings and tail folded, reducing the width to only six feet, for easy storage and transportability. The wings were fabric-covered spruce and the fuselage was of welded steel tubing, also fabric covered. An all-wood fuselage was available as an option if the customer desired it.

The 36 ft 5 in span, low-wing airplane was powered by a 75-hp Siemens engine which enabled it to cruise for three hours at 84 mph. The plane was capable of climbing to approximately 3,100 ft in six minutes. This was most satisfactory performance for a light, two-place, open-cockpit monoplane of the period. It was also capable of very efficient operations off water as a twin float airplane.

The very simple, yet clean lines of the HE 18 have held my attention for many years as a possible modeling subject. After having considerable success with several other small scale models using electric power, I decided to build it for the fine little HiLine Models' Mini-6 geared motor powered by three 100 mAh batteries. I had developed the drawings for rubber power, so it was a simple matter to convert the model to electric.

It flew right off the board, as they say, and it flew very well, indeed, demonstrating phenomenal stability. With a good one-minute charge, I consistently got flights of about 30 seconds. On one daring flight over a beautiful North Carolina sod farm, with a three-minute charge, the model climbed to well over 150 feet, hung a thermal and remained airborne for approximately 4-1/2 minutes. It was recovered intact and is currently still flying - though it needs new batteries and a bit of cosmetic attention.

Construction Highlights: Construction of the HE 18 is straightforward, entirely conventional, and very simple, so I will address construction highlights only.

The fuselage consists of two basic sides constructed of balsa strips. Notice that when the sides are joined, the top longerons are spaced closer together and there is a side stringer as well as the rounded turtle deck. I covered the forward top section with 1/16 balsa because it is easy to work with, and sanded it to approximately 1/32 thick before cutting the cockpit openings.

I built the tailplane members on my model as one piece, though the plan shows separation of fin and rudder, stabilizer and elevator joined by soft wire hinges. Floral wire is excellent for this, and it can simplify trimming the model. Each method is merely an option open to the builder.

The wings are built as two panels, joined at the roots by the balsa- and ply-spar doublers. These also serve as mounting points where the landing gear wire will be laced. The 1-1/8 in dihedral shown on the plan proved entirely adequate.

Although l show mounting for the HiLine motor, this may be modified by the builder. I would recommend locating a box for the batteries under the center of gravity. This will allow minor adjustments..."

Heinkel HE18, Model Aviation, November 1991.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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