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This aircraft is developed from the well-known Gothenburg Siegerrnaschine type H.E. 3 from 1923. The proven basic construction has been retained, but manufacturing improvements have been applied in order to achieve the reduction in price necessary for series production.
The aircraft is designed as a sports or training aircraft and can be flown as a land or water aircraft. The overall structure of the machine corresponds to these purposes in all
parts and is therefore kept particularly clear and simple, so that even non-expert personnel can handle it.
The aircraft is of the low-wing type with wings that are raised on one side. The latest aerodynamic requirements were largely taken into account in the design of the machine
. Using only flat or cylindrical surfaces on the fuselage, fabrication and consequently repairability
are significantly simplified. By eliminating complicated details and simplifying in all parts, series production and thus simplification have been taken into account as far as possible. For this reason, the entire organic structure can be described
as simple and practical: The fuselage of the aircraft is either designed as a tubular steel fuselage with fabric covering or entirely as a wooden fuselage with Fournier planking. To carry out the necessary repairs
in areas where the production of steel pipe material is difficultmade it necessary to use the all-wood version for these purposes. Students and teachers sit behind each other. The school control is designed as a stick control, but handwheel control can also be installed on request. In order to be able to fly the aircraft as a sports aircraft with a passenger, the front control system is set up for removal. The construction is designed in such a way that the removal of the school control system can be carried out without tools by releasing a quick-release fastener. In order to protect pupils and guides in the event of a rollover, a protective bar is attached over the middle of the fuselage from the motor shield to the rear edge of the teacher's seat, which can be easily dismantled.
Normally, the well-known 70-80 hp Siemens Stern engine is used, which
ensures vibration-free operation due to its favorable mass balance. However, the 5-cylinder Siemens Stern engine with 50-60 hp or another equivalent stationary or rotary engine (Le Rhone, Gnöme) can be installed on request. If Siemens Stern motors are installed, an electrical Bosch tempering system can be connected at the same time. In this case, the actuation is done by pressing the contact button on the dashboard and the engine spins and starts automatically.
The fire bulkhead is installed directly behind the engine. Behind it lies the gasoline case container at the top of the fuselage. The ignition torque adjustment is coupled directly to the engine with the throttle linkage in such a way that the ignition is automatically adjusted when the throttle is applied. A special operation of the ignition adjustment is therefore completely eliminated.
This operation of the engine can be done from both seats.
In order to enable an insight into the drive mechanism such as magnets, carburettors, etc., the engine is designed to be folded down and can be rotated around a vertical axis after loosening 2 bolts lying in a plane. There are no lines to loosen, as the fuel supply takes place through a metal hose. Since the oil tank is located directly on the engine, it is not necessary to loosen the oil supply.
The surface is normally executed. Spars and ribs are made of American spruce. Impregnated special material is used as covering. Ailerons are large
in size and are operated by a rigid connection. When it comes to surface construction, particular emphasis is placed on easy accessibility and repairability.
The continuous aileron is operated in the normal way and also has a lateral lever device with a locking device that allows the two ailerons to fold down evenly
. To reduce the landing speed, the lever device is operated, and the landing speed can be reduced by about 12-15% in this way. The arrangement of the mechanism is such that even with the ailerons folded down, it is possible to operate the connection with the control stick completely independently of this.
Due to an ingenious construction (D. R. P. a.) it is possible to fold the aircraft in the shortest possible time in such a way that the simplest transport and
shelter is given. The two wing halves and elevator fins can be dismantled by a single person and folded onto the fuselage. The
operation is as follows:
1. Anklappell of the elevator fins with elevator. The support strut of the elevator fin is raised by lifting aself-locking bolt on the fuselage, whereupon this
is folded up with the elevator, the right and left fins separately, without the control cable having to be loosened, since the connection between
the control stick and the elevator is a rigid one.
2. Folding the wing deck halves.
The two halves of the wing deck are held in place by 2 struts each, which attack it on both sides of the front and rear spars and on a common fitting of the upper hull spar. In order to dismantle the wing deck, the strut that engages the front spar is loosened on the wing deck fitting and folded forward to the fuselage. Then the connection of the wing front spar to the fuselage is uncoupled and the surface is rotated around the rear spar and placed vertically. During these operations, the surface is still held at the center of gravity by a strut and thus relieved in such a way that the assembly can be carried out by one person. In this position, it is swivelled backwards to the fuselage and attached to the fuselage by means of a locking device. In this folded state, the aircraft occupies a space of 7.2 m long, 1.9 m wide and 2.3 m high.
In this assembly, no special solution of the aileron connection tube is necessary, as the intervention is carried out with the mechanism located in the fuselage by means of a
jaw coupling. The assembly is carried out in reverse order. No tools are required for the entire assembly process.
The driving and float frames are interchangeable with each other without special auxiliary devices. The chassis is made of teardrop-profile tubular steel. The suspension
is in 2 suspension pots of the two front struts.
The float frame consists of a front and rear strut piece that engages with hook-shaped fittings of the floats. The two floats, which are separated by individual bulkheads, correspond in shape to those of the well-known and proven ocean-going aircraft. The floats are only stepped once, which makes it easier to sew up and drain in rough seas. The assembly and disassembly of the float and land chassis is also carried out without auxiliary tools using self-locking bolts.
The main data of the aircraft are, taking into account the 70-80 hp Siemens Stern engine: payload 220 kg, full load 620 kg, range of action 3 hours,
speed 145 km/h, climb time 1000 m in 6 min.
In view of the recent production in this country of a two-seater machine fitted with an engine of 60-70 h.p., and intended for school and sporting flying, i.e. the De Havilland " Moth " with " Cirrus " engine, described and illustrated in FLIGHT of March 5, it is of interest to know what other nations are doing in the matter of machines of approximately this power, and we are, therefore, pleased to be able to place before our readers this week details and illustrations of the new German machine which forms the subject of the following article. Owing to the limitations placed upon the size and power of German aircraft by the Versailles treaty, German designers have for the last few years been turning their attention to machines of a power permitted by the Allies, and have in consequence obtained considerable experience with machines of relatively low power. But for the absence of suitable German small engines, it seems likely that more would have been accomplished with really lowpower machines, of the type known in this country as light planes. As it is, most of the German light 'planes have been fitted with British motor-cycle engines. In the lowpower or " not-quite-so-light" plane class, however, the Germans designers have had available for several years engines of suitable type, and most of the German machines are, therefore, fitted with German engines, among which the two types of Siemens radial engines appear to have become most popular.
The Heinkel H.E. 18 shown in the accompanying illustrations was designed by Herr Ernst Heinkel, at one time chief designer to the Caspar works, but now established with his own firm, and constructed by that firm, the Heinkel Flugzeugwerke at Warnemiinde. The machine is the outcome of the Heinkel HE. 3 of 1923, which did so well at Gothenburg, and is very similar to its prototype except in certain minor alterations, made in order to cheapen the machine in quantity production.
Fundamentally the Heinkel H.F.. 18 is a low-wing monoplane with vee bracing struts as on the De Havilland D.H.53. One objection that has been raised against this type, and the only really serious one we have ever heard put forward, is the possible danger to the crew in case of the machine turning over on the ground. In the Heinkel two-seater provision is made against this by fitting a detachable steel tube guard running from the engine plate to the rear of the aft cockpit. In the photographs this guard is not shown in place, but it is stated that it can be fitted very quickly.
The fuselage is made in two distinct types, according to the requirements of the customer. The standard type, which is the one shown in the photographs, is of steel tube construction and covered with fabric. If, however, the machine is to be used under conditions or in localities where repairs to a steel tubular structure cannot easily be effected, an all-wood fuselage, with ply-wood covering, can be supplied instead.
This question of steel tube construction is one that might, we think, with advantage be taken up again now in this country in connection with low-power aeroplanes. The Fokker form of welded steel tube construction of fuselages is probably the cheapest ever devised, and one very great advantage of it is its adaptability. The change from one shape or size of fuselage to another can be very easily and simply made, and thus the risk of premature standardisation does not arise. Theoretically, it is true, the welded form of construction is open to criticism, but practical experience with the Fokker machines seems to show that the fears of the theorists are not well founded. We do not suggest a slavish copying of Fokker's methods, and would avoid the use of welded joints in tension, but much of the method does appear to be very useful, and it would be interesting to have a ruling from the Air Ministry as regards the application to light 'planes.
However, to return to the " H.E. 18," the two cockpits are arranged in the usual way, the pilot or instructor, as the case may be, occupying the rear cockpit and the passenger or pupil the forward one. Dual controls of the usual " stick " type are provided, but that of the pupil can be removed, without the use of tools, in a few moments. The engine, which is, in the type illustrated, a 7-cylinder
radial air-cooled Siemens rated at 70-80 h.p., but which may be a Siemens 5-cylinder radial of 50 h.p., or any other type desired, is mounted on a swivelling engine plate, which allows of inspecting the back of the engine, with carburettor, magneto, etc., without disconnecting any leads. Aft of the engine is a fireproof bulkhead, and the petrol tank is mounted in the deck fairing aft of this bulkhead, where sufficient head is provided to give direct gravity feed.
The monoplane wings are of normal construction, with spruce spars and ribs, and are chiefly remarkable for the arrangement made for folding. The ailerons run the whole length of the wings, and are stated to give very effective lateral control. By means of a special arrangement the ailerons are also used as variable camber flaps for slow landing, the camber variation being effected by means of a lever in the pilot's cockpit, and the aileron action being retained.
Reference has been made to the wing folding arrangement, which is designed to enable the owner-pilot himself to fold the wings without assistance. The operation consists in folding the two halves of the monoplane wing against the sides of the fuselage, the space in the folded position being further reduced by folding the tail plane against the fin and rudder. The wing-bracing struts are not detached from the fuselage, and in fact the rear strut is not disturbed at all.
The front strut is cast off at the front spar attachment and swung forward against the side of the fuselage, where it is held in position by a clip. The quick-release attachment of the front spar to the fuselage is next released, the wing is swung into a vertical position, leading edge uppermost, and folded along the sides. Doing one side at a time, the pilot can easily fold the wings himself without outside assistance, and the machine can then be stowed in a very small space, or trailed after a motor-car or motor-bicycle.
The undercarriage shown in our photographs is of the simple V-type, but in the general arrangement drawings a different form is illustrated, probably with a view to indicate the easy transformation of the machine into a seaplane of the twin-float type. The photograph showing the " H.E.18 " as a seaplane indicates a balanced elevator, so that apparently slightly larger tail surfaces are fitted when the machine is used as a seaplane.
The main dimensions of the Heinkel " H.E.18 " are :
Length, o.a., 7 -20 m. (23 ft. 7 ins.); Span, 11.10 m. (36 ft. 5 ins.) Total Wing Area, including Ailerons, 188 sq. ft. ft. Weight of machine empty 380 KGS. (836 lb.) ; useful load, 220 kgs. (484 lbs.) ; total loaded weight, 600 kgs. (1,320 lbs.) Maximum speed, 150 km./h. (93-7 m.p.h. ; cruising speed, 140 km./h. (87 m.p.h.). Climb to 1,000 m. in 6 minutes.
No figures are available relating to the landing speed, but in view of the relatively high wing loading this is probably fairly high

A Heinkel HE 18 from the Technical University of Braunschweig. The HE 18 was built in only 2 copies, one of which went to the flight science group of the TH Braunschweig (to be read on the tail ). Initially, an old Daimler pre-war engine with 70 hp was installed there, in 1925 the aircraft was converted to a - then - modern Junkers L1 with 80 hp, and in 1929 the aircraft broke down.
The Heinkel HE 18 was a further development of the HE 3, but with seats in tandem arrangement and braced wings, these could be folded