O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Friedrichshafen 33 Variants

   The FF 33s were undoubtedly the most multifarious of the early German patrol seaplanes. Nevertheless, their many variants could be basically divided into two categories. The 33/33b, 33e, 33j and 33s, which were mostly unarmed reconnaissance patrol seaplanes carrying a small load of bombs, were all of three-bay wing format. The 33f, 33h and 331, on the other hand, were fighters of two-bay wing layout, intended for armed patrols and on occasion for escort to reconnaissance patrol machines.

   The Reconnaissance FFs. Stemming from the FF 33, all variants were of basically similar airframe construction, with differing engine, equipment installations, flotation gear and wingspan, as will be outlined later. The initial FF 33 appeared at the end of 1914 and was a quite orthodox fabric-covered wooden structure in which the pilot sat in the aft cockpit. Like the earlier FF 29, it was powered with a 120 h.p. Mercedes D II engine, and in general differed little except for modification of the float shape. The fuselage was a simple slab-sided braced box-girder structure of spruce longerons and spacers tapering to a vertical knife-edge, and with a slightly rounded top decking. A small amount of sweepback was incorporated in the wings, which were based on two main spars with wooden ribs, the trailing edges of which were linked with a wire member which imparted a scalloped effect to the profile. The ailerons, of inverse taper, were of steel-tube construction, likewise the tail assembly, and of these control surfaces only the rudder was balanced. However, only six aircraft of this type were supplied to the German Navy.
   In the F F 33b, which followed, the positions of the crew were reversed, with the pilot now sitting in the forward position. In the rear cockpit the observer was equipped with a manually operated machine-gun for defence purposes. A more powerful engine, the 160 h.p. Maybach, was fitted and the radiators were sited on the fuselage sides adjacent to the front cockpit. The floats were of two-step design, with flat bottoms forward and vee section aft. As far as is known, only five of this type were built.
   The next variant was the FF 33e, which was still generally similar to its predecessors but differed most noticeably in the float arrangement, the main floats being considerably lengthened and the tail float abandoned. In its place a long underfill was substituted, and this became a characteristic of practically all subsequent Friedrichshafen aircraft. This modification of the float system resulted in the most seaworthy machine to date. Another variation from the earlier machines was the installation of the 150 h.p. Benz Bz. III engine, the reliability of which was superlative for long "over water" patrols. With this engine the radiator system was again revised, the cooler now being located against the leading edge of the top wing. The FF 33e was the first of the series to be equipped with radio-telegraphy equipment, but at this stage only a transmitter was fitted. No defensive armament was installed, as development of protection escort machines was proceeding simultaneously. Some 188 FF 33es were constructed from March 1915 onwards, the final batch supplied from September 1917 to January 1918 being equipped solely as school machines and fitted with dual control.
   A further refinement in the series came with the FF 33j, the most noticeable feature of which was the cleaning up of the nose-entry and the addition of a spinner to the propeller hub. A headrest for both pilot and observer was fitted, and altogether a much more pleasing appearance resulted. Both transmitting and receiving radio equipment was now installed, which made for an all-round improvement in communications. Furthermore, tools, spare parts and sea anchors were carried to facilitate repair in case of forced alighting; also full navigation equipment and signalling gear was installed.
   Doubtless the most famous of all the FF seaplanes was the 33e "841" Wolfchen carried by the German auxiliary cruiser Wolf, whose depredations from November 1916 to February 1918 extended as far as the Indian and Pacific Oceans. Wolfchen was hoisted overboard on a derrick and tackle and proceeded to scout ahead of the cruiser, sending by radio to her parent ship such intelligence as became available. In all, some fifty-six flights were carried out during this period, and between each considerable maintenance was often necessary. This represented a commendable achievement on the part of all concerned, particularly as the aircraft had to be protected as much as possible against the effects of exposure and tropical climates.
   Translated extracts from the Wolfchen log exemplify accomplishment:
   "Pacific Ocean. 2nd June 1917. Orders. Merchant steamer which has been sighted to North of Raoul Island to be stopped and brought to Wolf."
   The ship had suddenly appeared while Wolf was hove-to close to the island, engaged on engine repairs and trimming bunkers. Wolfchen started at 15.30 hours and flew north. On reaching the steamer the FF 33e descended to within 200 feet and dropped the following message in English:
   "Steer south to German cruiser and do not use wireless. If not obeyed you will be bombed."
   The second time the seaplane flew over the steamer it dropped a bomb only 20 yards from her bows. At once she changed course and steered for Wolf, escorted by Wolfchen. After this threat she did not use her wireless. It was the New Zealand ship Wairuna of 3,900 tons, bound for San Francisco from Auckland. The ship and her cargo were worth many hundred thousand pounds.
   "Pacific Ocean. 16th June 1917. Orders. Hold up four-masted schooner sighted in the west and bring to Wolf''
   Wolfchen started at 15.50 hours and flew west. It spiralled down from 500 to 250 feet. Its first two attempts to drop a message on the deck failed owing to the drift of the vessel. Both fell some distance to leeward. At the seaplane's third approach a bomb was dropped from 250 feet close by the bows. The ship at once hauled in sail and displayed the United States flag. Wolfchen ordered the vessel to steer south-east and intimated that she would be bombed if she did not follow. She at once turned in the given direction, and with Wolfchen circling overhead, was led to Wolf. It was the American schooner Winslow of 567 tons, with a cargo of coal, provisions, petrol and timber, from San Francisco. Unfortunately the petrol was useless for aircraft. Owing to bad weather, Wolfchen was again dismantled and stored away on the afternoon of 17th June 1917.
   "Indian Ocean. 25th September 1917. Orders. Investigate patch of smoke which has been sighted and report on vessel, course and distance."
   It proved to be the Japanese ship Hitachi Maru of 6,900 tons. The Wolfchen received a further order to support Wolf in holding up the vessel and to bomb her if she committed any hostile act. At the first shot from Wolf the ship turned to starboard intent upon escape. Thereupon a bomb was dropped about 30 yards ahead of her; about the same time the cruiser again fired, so that Wolfchen was led to believe that the ship was resisting. Wolfchen therefore flew up again and dropped another bomb from about 700 ft., which fell close by the port side. The explosion blew two men overboard and the steamer then hove to. Wolfchen then ceased bombing, but continued to circle round until the prize crew had gone on board.
   The seaplane then alighted close by the vessel and discovered that the nuts on the propeller had loosened, and, in consequence of the lash on the prop-shaft, the engine could not throw true against the cranks.
   The final variant of the reconnaissance FF 33 machines was the 33s, which was simply a 33j equipped with dual control for use solely as a school aircraft.

   The Fighter Patrol FFs. The principal visible difference between the reconnaissance and fighter FFs was in the reduction of overall dimensions and the introduction of two-bay wing format to improve manoeuvrability. The 150 h.p. Benz engine still remained the standard power unit.
   First of these two-seat fighter patrol types was the 33f, introduced in October 1915 and probably the first German naval lighting scout. Armament was a manually operated Parabellum gun for the observer. However, no more than five of these machines had been supplied when the type was superseded by the FF 33h. In this model the nose-entry was improved. Some had a radiator of aerofoil section built into the centre-section of the top wing. The ailerons and floats were also redesigned, all with a view to reducing head resistance. Modification to the float chassis included the introduction of steel-tube load struts between the floats instead of only cables as previously. Some inboard bay bracing cables were duplicated as a precaution against breakage should the gunner decide to shoot between the prop disc and the struts (as he was expected to do if necessary!) and sever one of the wires. Coming into service in January 1916, the 33hrs continued to operate until eventually some forty-five were in service.
   In September 1916 the FF 33l was introduced, and production finally totalled some 135 aircraft. The fuselage length and wingspan were still further reduced, a spinner was fitted to the propeller and, finally, the aircraft achieved a reasonably happy compromise between performance and manoeuvrability - a prerequisite that plagues the design of all naval aeroplanes. For a somewhat cumbersome machine the 33l possessed marked agility, and this enabled the pilot to make use of the fixed forward gun which was now added to the armament. Its degree of seaworthiness was reasonably good, and take-off and landing from open sea in winds up to force 3 could be accomplished. On some machines the forward gun was deleted and a radio transmitter carried in its stead. By and large, the FF 33ls were able to afford a good degree of protection for their unarmed reconnaissance brethren on long patrols over the North Sea.

TECHNICAL DATA
   Description:
   Two-seat reconnaissance patrol twin float seaplane (33e).
   Two-seat fighter patrol escort twin float seaplane (331).
   Manufacturers: Flugzeugbau Friedrichshafen G.m.b.H. Manzell and Warnemunde.
   Power Plant: One 150 h.p. Benz Bz III 6 cylinder in-line water-cooled engine.
   Dimensions: Span, 16.75 m. (54 ft. 11 1/2 in.), 33e; 13.3 m. (43 ft. 7 5/8 in.), 33l. Length, 10.45 m. (34 ft. 3 1/2 in.), 33e; 8.825 m. (28 ft. 11 1/2 in.), 33l. Height, 3.725 m. (12 ft. 2 5/8 in.), 33c; 3.95 m. (12 ft. 10 1/2 in.), 33l. Wing area, 52.7 sq.m. (569.2 sq.ft.), 33c; 40.54 sq.m. (437.8 sq.ft.), 33l.
   Weights: Empty, 1,008 kg. (2,217.6 lb.), 33e; 916 kg. (2,021.8 lb.), 33l. Loaded, 1,635 kg. (3,636.6 lb.), 33e; 1,373 kg. (3,020.6 lb.), 33l.
   Performance: Maximum speed, 119 km.hr. (74.5 m.p.h.), 33e; 136 km.hr. (85 m.p.h.), 33l. Initial climb, 1,000 m. (3,280 ft.) in 17.5 min., 33e; in 8 min., 33l. Duration, approximately 5-6 hr., both types.
   Armament:
   33e - None. (Some aircraft fitted with rear gun.)
   33l - One fixed Spandau machine-gun forward and one manually operated Parabellum machine-gun in rear cockpit.

   N.B. Data is general. Nearly all production machines had detail differences rom batch to batch.

J.Herris Friedrichshafen Aircraft of WWI (A Centennial Perspective on Great War Airplanes 21)

Friedrichshafen FF33 Series

   Of the 854 seaplanes Friedrichshafen provided to the Navy, 427, or half, were from the FF33 family. Friedrichshafen's seaplanes were consistently more robust and reliable than those from competing manufacturers and had good flying and seakeeping qualities, the key reasons Friedrichshafen aircraft dominated the Navy's production orders. While combat aviators greatly appreciate sparkling performance, reliability is even more important, and that is especially true of seaplanes. Survival time in cold northern waters is often measured in minutes if the seaplane lets the crew down, so reliability is a seaplane's most important quality. Friedrichshafen's seaplanes did not have the exceptional high-altitude performance of Rumpler reconnaissance planes nor the remarkable maneuverability of the Fokker Triplane, but they excelled in reliability. That gained them leadership in the competition to provide reconnaissance seaplanes to the German Navy. And Friedrichshafen's FF33 family built that leadership.
   The first orders for Friedrichshafen's FF33 were placed in December 1914, with the first aircraft delivered in April 1915. The final FF33 orders were placed in March 1918, with deliveries completed in November 1918. Given the pace of aircraft development during the war, this longevity of one design was remarkable and a testament to its flying qualities and robust structure.

Reconnaissance & Fighter Variants

   The FF33 series included both 3-bay aircraft designed for reconnaissance or training (FF33, FF33B, FF33E, FF33J, and FF33S) and armed two-bay aircraft intended for fighting (FF33F, FF33H, and FF33L). It is still uncertain why all these designs were called variants of the basic FF33 and what the common design elements were throughout the entire series. Certainly Army aircraft types with smaller differences between them were given different type designations.
   On the other hand, Army aircraft were generally ordered in large batches compared to Navy aircraft, for which a typical production batch was five or ten aircraft. This resulted in significant variations between production batches of naval aircraft of the same type.

FF33 & FF33A

   The initial FF33 order was placed in December 1914 for the variant known as the FF33A. These six aircraft, MN 416-421, were all powered by the 100 hp Mercedes D.I. The FF33 variant, MN 426 and 451-455, were powered by the 120 hp Mercedes D.II. Actually, they were under-powered and subsequent aircraft in the FF33 series had more power.

FF33B & FF33D

   The next members of the FF33 family were the FF33B and FF33D. In an endeavor to provide enough power, these aircraft were powered by the 160 hp Maybach. The FF33B were MN 456-458, class BFT, and the FF33D were MN 459-460, class CB; at this time class CB meant an armed two-seat reconnaissance type. At this early stage of the war Maybach engines were primarily intended for airships and production capacity was insufficient to support naval aircraft requirements in addition; no more FF33 aircraft received Maybach engines.

FF33C

   The next production order for FF33 series aircraft was for the FF33C, MN 471-473. These aircraft were class BFT and received 160 hp Mercedes D.III engines, the first FF33 series aircraft to receive the more powerful Mercedes and also the last until the Roland-built FF33S trainers were ordered in November 1917. Despite their Mercedes engines, these aircraft were the production prototypes for the FF33E aircraft that was powered by the 150 hp Benz Bz.III. In fact, the official Atlas deutscher und auslander Seeflugzeuge designated MN 471-473 as FF33E aircraft (see the SVK table on page 6), but SVK war diary records them as being delivered as FF33C aircraft. MN 471 was delivered to the SVK on April 6, 1915 and was accepted on April 10 pending successful sea-keeping based on the tests to come. Subsequently, FF33C MN 472 arrived at SVK on May 11 and was accepted on May 18, and FF33C MN 473 was delivered on May 22 and accepted on June 19.
   The three FF33C aircraft were intensively tested by the SVK and did so well all three were sent to operational units. MN471 went to Borkum, MN472 went to Zeebrugge, and MN473 flew to Putzig.

FF33E

   With the success of the FF33C aircraft during testing at the SVK, the first FF33E production order soon followed. The main difference between the types was the 150 hp Benz used in the FF33E aircraft, further Mercedes engines being assigned to Army aircraft until late in the war. MN 479 was the first FF33E to reach operational service, arriving at Libau naval air station on August 18, 1915.
   The FF33E was ordered to fulfill a number of duties. Those class B could carry a few light bombs and were used for operations and training. Those class BFT could carry light bombs and a wireless transmitter, and were used for armed reconnaissance. Those class HFT could carry light bombs and a wireless transmitter and receiver, and like their class B siblings were used for armed reconnaissance. Only one FF33E, MN 510, was class C, an armed two-seater.

FF33F

   Essentially, the FF33F was the armed version of the FF33E; the FF33F was class C, an armed two-seater with one flexible gun. Only one small batch of FF33F aircraft, MN 534-538, were built.

FF33H

   The next member of the FF33 series was the FF33H, the FF33G designation apparently not being used for an aircraft actually built. The FF33H aircraft were class C, armed two-seaters with one flexible gun. However, they differed from previous variants in that they were more compact, two-bay aircraft instead of three-bay aircraft. The intention of this design change was to improve their maneuverability and speed during combat, for which they were armed, but without a fixed gun for the pilot. The FF33H was built in a series of small batches interspersed with batches of the FF33E; see the tables for details.

FF33J

   The FF33J was the next production variant of the series. It was a three-bay aircraft, class HFT, and designed for the same roles as the FF33E. Small batches (MN 922-931, MN 1095-1104, MN 1289-1298, and MN 3031-3060) totalling 60 aircraft were built. The FF33J had a more streamlined nose than the FF33E with a propeller spinner the FF33E lacked and also had a streamlined headrest for the observer.

FF33K

   The FF33K was a step toward the FF33L. It was a two-bay, class C2MG aircraft. Only one aircraft, Marine Number 932, was built as the first aircraft of the first FF33L production batch. The FF33K had a larger wingspan than the definitive FF33L and its tail surfaces were similar to the older FF33 series aircraft instead of the more refined surfaces of the FF33L.

FF33L

   The final and best FF33 variant was the FF33L, a two-bay floatplane with a more streamlined nose for better performance. The first order was placed in September 1916, and ordered continued into February 1917. A total of 125 FF33L aircraft were
built, 40 in class C2MG and 85 class CHFT. The FF33L was fairly agile for its size and the class C2MG aircraft, with their fixed gun for the pilot, were particularly suited for escort and offensive use. The FF33L did not possess the maneuverability or speed of the later Brandenburg W.12, but the FF33L was more robust and could operate in higher sea states than the W.12.
   Like many naval aircraft, the FF33L underwent modifications between its relatively small production batches, the most noticeable of which were changes in the vertical tail surfaces. The first change started with batch 1158-1177, which featured a new tail design that eliminated the fin. FF33L #3144 was also tested with new tail surfaces, although these was not adopted for production.

FF33S

   The dual-control FF33S was the dedicated training version of the FF33E. One batch, MN3001-3030 was ordered from Friedrichshafen and two from Roland (789-790 and 6501-6520) for a total of 52 aircraft.


Friedrichshafen FF33 Series Production
Type Marine Numbers Quantity Date Ordered Naval Class & Notes
FF33A 416-420 5 December 1914 100 hp Mercedes D.I
FF33A 421 1 December 1914 B, 100 hp Mercedes D.I
FF33 426 1 November 1914 B, 120 hp Mercedes D.II
FF33 451-455 5 January 1915 B, 120 hp Mercedes D.II
FF33B 456-460 5 January 1915 CB, MN 459-460 were the FF33D
FF33C 471-473 3 March 1915 BFT, 160 hp Mercedes D.III
FF33E 478-483 6 June 1915 BFT
FF33E 491-496 6 June 1915 BFT
FF33E 497-508 12 August 1915 BFT
FF33E 510 1 August 1915 C
FF33E 529-533 5 October 1915 B
FF33F 534-538 5 October 1915 C
FF33E 541-550 10 November 1915 BFT
FF33E 553-562 10 November 1915 BFT
FF33E 591-595 5 January 1916 BFT
FF33H 596-600 5 January 1916 C
FF33E 633-637 5 January 1916 BFT
FF33H 638-642 5 January 1916 C
FF33E 659-663 5 March 1916 BFT
FF33H 664-668 5 March 1916 C
FF33E 680-684 5 April 1916 BFT
FF33H 685-689 5 April 1916 C
FF33E 690-694 5 April 1916 BFT
FF33H 695-699 5 April 1916 C
FF33E 715-724 10 May 1916 BFT
FF33E 725-729 5 May 1916 HFT
FF33H 730-734 5 May 1916 C
FF33E 736-740 5 May 1916 HFT
FF33H 741-745 5 May 1916 C
FF33S 789-790 2 November 1917 S, Roland built, Mercedes D.III
FF33E 802-811 10 May 1916 HFT
FF33H 812-821 10 May 1916 C
FF33E 822-841 20 June 1916 HFT
FF33E 850-859 10 July 1916 HFT
FF33E 860-869 10 July 1916 B
FF33E 870-881 12 August 1916 HFT
FF33E 882-884 3 September 1916 HFT
FF33E 885-889 5 August 1916 B
FF33J 922-929 8 September 1916 HFT
FF33J 930-931 2 September 1916 HFT

Friedrichshafen FF33 Series Production
Type Marine Numbers Quantity Date Ordered Naval Class &, Notes
FF33L 932-941 10 September 1916 C2MG; 932 was the sole FF33K
FF33L 1001-1010 10 November 1916 CHFT
FF33L 1085-1094 10 October 1916 CHFT
FF33J 1095-1104 10 October 1916 HFT
FF33L 1117-1126 10 December 1916 C2MG
FF33L 1158-1177 20 January 1917 CHFT, revised tail
FF33L 1234-1278 45 February 1917 CHFT
FF33L 1279-1288 10 February 1917 C2MG
FF33J 1289-1298 10 February 1917 HFT
FF33E 1577-1596 20 June 1917 C2MG
FF33E 1980-1999 20 September 1917 S
FF33S 3001-3030 30 December 1917 S
FF33J 3031-3060 30 March 1918 HFT
FF33L 3144-3153 10 Late 1918 C2MG
FF33L 3154-3193 40 Late 1918 C2MG,- order cancelled December 1918
FF33S 6501-6520 20 November 1917 S, Roland built, Mercedes D.III
Note: Unless noted otherwise in the tables, all FF33 series aircraft had the 150 hp Benz Bz.III. Some early FF33 aircraft had Mercedes or Maybach engines prior to an agreement between the Army St Navy that reserved Mercedes engines for Army aircraft and allocated some Benz engines to the Navy. Later, when Mercedes production caught up to demand somewhat, a few naval aircraft like the FF33S aircraft built by Roland were given Mercedes engines.

Friedrichshafen FF33 Subtype Specifications
Specification FF33 FF33A FF33B & D FF33E & F
Engine 120 hp Mercedes D.II 100 hp Mercedes D.I 160 hp Maybach Mb.HI 150 hp Benz Bz.III
Span, Upper 16.75 m 16.75 m 16.80 m 16.80 m
Span, Lower - - - 15.15 m
Wing Area - - 60.00 m2 52.70 m2
Length - - 10.20 m 10.27 m
Height - - 3.73 m 3.73 m
Empty Weight 1,000 kg 1,000 kg 1,010 kg 984-1,010 kg
Loaded Weight 1,600 kg 1,600 kg 1,655 kg 1,635-1,675 kg
Max Speed 110 km/h - 100 km/h 119-128 km/h
Cruise Speed - - - 110 km/h
Range - - - 600-700 km
Climb to 500 m - - - 5-7 minutes
Climb to 1,000 m - - - 9.9-15.5 minutes
Climb to 1,500 m - - - 16-28 minutes
Note: FF33E/F weight and performance specifications vary depending on production batches.

Friedrichshafen FF33 Subtype Specifications
Specification FF33H FF33J FF33K FF33L
Engine 150 hp Benz Bz.III 150 hp Benz Bz.III 150 hp Benz Bz.III 150 hp Benz Bz.III
Span, Upper 14.20 m 16.70 m 14.20 m 13.20 m
Span, Lower 12.66 m 15.00 m 12.66 m 11.70 m
Wing Area 43.40 m2 52.50 m2 43.40 m2 40.54 m2
Length 9.60 m 10.30 m 9.60 m 8.95 m
Height 3.75 m 3.72 m - 4.00 m
Empty Weight 948 kg 1,045 kg 948 kg 917 kg
Loaded Weight 1,477 kg 1,585 kg 1,477 kg 1,388 kg
Max Speed 123 km/h 125 km/h 135 km/h 139 km/h
Cruise Speed - 115 km/h - -
Range 615 km 550 km 675 km 450 km
Climb to 500 m 4.5 minutes - 7 minutes -
Climb to 800 m - - 12.5 minutes 6 minutes
Climb to 1,000 m 11 minutes - 16.5 minutes 8 minutes
Climb to 1,500 m 18.5 minutes - - 13.5 minutes

German Naval Aircraft Classes
Class Meaning
B Two-seat aircraft with bombing equipment
BFT Two-seat aircraft with bombing equipment and wireless transmitter
Bu U-boat aircraft (U-Boot Flugzeug]
C Two-seat aircraft with one flexible machine gun
C2MG Two-seat aircraft with one flexible and one fixed machine gun
C3MG Two-seat aircraft with one flexible and two fixed machine guns
CHFT Two-seat aircraft with one flexible machine gun and wireless transmitter and receiver
CK Two-seat aircraft with one flexible cannon and one or two fixed machine guns
E Single-seat flying boat (Einsitzerboot]
ED Single-seat aircraft with twin floats [Einsitzer mit Doppelschwimmer)
ED2MG Single-seat aircraft with twin floats and two machine guns
FL Aircraft for control of wire-guided attack boats (Fernienkflugzeug)
G Twin-engine aircraft [Grossflugzeug)
HFT Two-seat aircraft with bombing equipment and wireless transmitter and receiver.
R Aircraft with three or more engines [Riesenflugzeug)
S Two-seat training aircraft with dual controls [Schulflugzeug)
T Torpedo aircraft [Torpedoflugzeug)
U Practice aircraft (Uebungsflugzeug fur Alleinflieger)
V Test aircraft (Versuchsflugzeug zur Erprobung von Motoren, Propellern, Instruments, usw.)

J.Herris German Seaplane Fighters of WWI (A Centennial Perspective on Great War Airplanes 2)

FF33L - Fighter Forerunner

   The main purpose of fighter aircraft is to attack enemy aircraft. Some early fighters like the Vickers Gunbus and SPAD pulpit fighters had a gunner with flexible gun and no gun for the pilot, but the fighter soon evolved and a fixed gun for the pilot became essential. Thus to be included in this work, a fixed gun for the pilot was a requirement, and the C2MG variant of the Friedrichshafen FF33L qualifies. Of the 145 production FF33Ls, 60 were the C2MG category with fixed gun for the pilot; the other 85 were category CHFT with wireless transmitter and receiver and a flexible gun for the observer, but no gun for the pilot. An additional 40 of the C2MG version of the FF33L were ordered but not built and the order was cancelled in December 1918.
   The FF33 series was built in greater numbers, 491, than any other German naval aircraft and perhaps any WWI floatplane. The early FF33A and FF33B were unarmed reconnaissance seaplanes built in small numbers. The main early production aircraft was the FF33E, also an unarmed reconnaissance floatplane. The FF33H was an armed development of the FF33E with a flexible gun for the observer and smaller span for better maneuverability. The FF33J was a replacement for the FF33E and the FF33S was a trainer.
   The FF33L, the final version of the large FF33 family, was designed for use as an escort and patrol fighter and its C2MG variant was the first German seaplane to mount a fixed gun for the pilot. The FF33L was developed from the FF33H and was somewhat smaller and more streamlined than earlier FF33 floatplanes to increase speed and maneuverability compared to its general-purpose ancestors. For a seaplane of the time the FF33L had good maneuverability and handling and fair speed, and it was an effective escort for its unarmed reconnaissance companions over the North Sea and Baltic.
   While its offensive capabilities were modest, the C2MG valiant of the FF33L was the transitional design to the floatplane fighter and showed the need for more effective aircraft like the faster, more maneuverable Brandenburg W12 that truly warranted being called fighters through their enhanced offensive combat capability.

FF33L Production Orders
Marine Numbers Category Qty Delivery Dates
932-941 C2MG 10 Jan.-Feb./1917
1001-1010 CHFT 10 Mar.-July/1917
1085-1094 CHFT 10 Apr.-June/1917
1117-1126 C2MG 10 Apr.-June/1917
1158-1177 CHFT 20 Apr.-June/1917
1234-1278 CHFT 45 May-Oct./1917
1279-1288 C2MG 10 June/1917
1577-1596 C2MG 20 Aug.-Sep/1917.
3144-3153 C2MG 10 Late 1918
3154-3193 C2MG 40 Cancelled 12/18
Marine #3144 had an experimental tail design.


FF33L Specifications
Engine 150 hp Benz Bz.III
Span 13.3 m
Length 8.825 m
Wing Area 40.54 sq. m.
Empty Wt. 916 kg
Gross Wt. 1,373 kg
Max Speed 136 km/h
Climb to 1,000 m 8 minutes
  

J.Forsgren Swedish Military Aircraft 1911-1926 (A Centennial Perspective on Great War Airplanes 68)

Friedrichshafen FF 33L

  When, in September 1917, the Kriegsamt stated its intention of selling five airplanes to Sweden, the MFV reacted quickly, asking for the delivery of five maritime reconnaissance airplanes. Although funds were forthcoming, it was not until April 17, 1918, that a formal contract for two Friedrichshafen FF 33L’s and three FF 33E’s (see below) was signed. Following inspection in Germany, the two FF 33L’s were delivered in August 1918. No armament was fitted to the airplanes, which were issued with the serial numbers Fb 18 and Fb 19 respectively. Tragically, the former was lost in a fatal crash at Helsingborg on October 4, 1919. The second FF 33L was destroyed by fire on August 5/6, 1921.
  Prior to the last two Thulin G’s being withdrawn from use, it was decided on June 30, 1920 to manufacture two FF 33L’s at the Stockholm naval yard as replacement airplanes. Being completed in 1922, they were issued with the same serial numbers, Fb 18 and Fb 19, as the original two FF 33L’s. Prior to being destroyed, the sole remaining original FF 33L was copied in minute detail. Nevertheless, the flight and handling characteristics of the Swedish-built airplanes were very poor. According to the MFV pilot Albin Ahrenberg: ’’These ... Friedrichshafen planes (were) very beautiful to look at, but incredibly difficult to get a some sort of understanding of while in the air. I wrestled with the first test airplane for almost one year, but hardly managed in improving it. It would make the most absurd things, if I wanted fly in one direction, the plane wanted to go the other way.”
  Both were still in service when Flygvapnet was established on July 1, 1926. Issued with the serial numbers 218 and 219 and the designation Sk 2 {Skolflygplan 2, ie Training Airplane Type 2), they were flown very sparingly before being struck off charge in 1929.

Friedrichshafen FF 33L Technical Data and Performance Characteristics
   Engine: 1 x 150 h.p. Benz
   Length: 8,95 m
   Wingspan: 13,20 m
   Height: 3,70 m
   Wing area: n/a
   Empty weight: n/a
   Maximum weight: 1,115 kg
   Maximum speed: 130 km/h
   Armament: -


Friedrichshafen FF 33E

  Three FF 33E’s were delivered on September 11, 1918, being issued with the serial numbers Fb 20 to Fb 22. Following the loss of serial number Fb 21 on May 20, 1919, it was decided to build at replacement airplane at the Stockholm naval yard. It was decided to construct a ’’more aggressive” airplane by reducing the wing area, as well as redesigning the tail section, wing struts and propeller. The redesigned FF 33E became known as the Type 20-22 Swedish. The replacement FF 33E received the same serial number, Fb 21, as the one lost in a crash. Another two FF 33E’s were built at the Stockholm naval yard in 1924, becoming serial numbers Fb 16 and Fb 17. Apart from maritime reconnaissance, the FF 33E’s were used as basic trainers, being fitted with a double set of controls.
  Two FF 33L’s were written off in quick succession in 1925, May 7 (Fb 17), July 1 (Fb 20) and September 21 (Fb 21) respectively.
  One FF 33E, serial number Fb 22, was fitted with a 180 h.p. Mercedes engine, which improved overall performance.
  Two FF 33E’s remained in service in July 1926, becoming 216 and 222 in Flygvapnet service, being designated Sk 2 {Skolflygplan 2, ie Training Airplane Type 2). They were struck of charge in July 1927 (222) and November 1927 (216) respectively, having seen little use.

Friedrichshafen FF 33E Technical Data and Performance Characteristics
   Engine: 1 x 150 h.p. Benz
   Length: 10,22 m
   Wingspan: 16,60 m
   Height: 3,48 m
   Wing area: 52,00 m2
   Empty weight: 1,160 kg
   Maximum weight: 1,580 kg
   Maximum speed: 112 km/h
   Armament: -

M.Dusing German Aviation Industry in WWI. Volume 2 (A Centennial Perspective on Great War Airplanes 85)

Flugzeugbau Friedrichshafen, Manzell near Friedrichshafen (Fdh)

  On June 25,1912, the company "Flugzeugbau Friedrichshafen" was founded by Dipl.-Ing. Kober as a limited liability company. Count v. Zeppelin was also a shareholder in the company. In addition to the main factory in Friedrichshafen, the company also had a department in Weingarten (Wurttemberg) and a shipyard in Warnemunde.


Aircraft Development:

  As already mentioned, the company was primarily engaged in the construction of seaplanes. Of them, worth mentioning are:
   FF 33 with 150 hp Benz and 160 hp Mercedes engine, 1913/15 for bombing, wireless telegraphy and machine gun;
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  Repeatedly, pilots could be rescued after engine failures, their planes sometimes floating around in capsized condition for days on the North Sea. The bombing flights over London and other cities and installations in England and Belgium also testified to the usefulness of these aircraft.
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А.Александров, Г.Петров Крылатые пленники России

В морской авиации также использовался класс Ц. 20 сентября 1916 г. у берега о-ва Руно, что в Рижском заливе, после вынужденной посадки, случившейся при возвращении с разведывательного полета к Моонзунду и Аренсбургу, в руки русских пилотов попал германский двухпоплавковый биплан "Фридрихсхафен ФФ. 33", модель Фау-8 образца 1916 г. (Friedrichshafen FF 33h, "h" - восьмая буква немецкого алфавита), с мотором "Бенц" 160 л. с. Аппарат потребовал лишь малого ремонта, а затем перелетел в Ревель, где его отрегулировали и зачислили в списки флотской авиации под кодовым номером АБ-1 ("Альбатрос" с "Бенцем"-первый). Новая карьера продлилась недолго: в апреле 1917 г. самолет передали заводу В. А. Лебедева для последующего копирования. Однако заказ на 175 подобных гидроаэропланов не был выполнен, к тому же к осени 1917 г. конструкцию уже считали устаревшей. Сфотографированный во дворике завода Лебедева на Комендантском аэродроме Петрограда (46, а), фюзеляж "Фридрихсхафена" предстает перед нами с закрашенными бортовыми и хвостовыми крестами и номером, с демонтированными крыльями, поплавками и стойками. В его задней кабине оставлена пулеметная турель (46, б), под который заметна шнуровка обшивки и ступенька для подъема и спуска наблюдателя. Некто в шляпе демонстрирует, как легок хвост самолета (46, в), при этом на обеих частях стабилизатора и на рулях глубины видны, по крайней мере, на оригинале, германские морские номера аппарата - 698. На заднем плане заметна часть вывески "Общество воздухоплавания В. А. Лебедева". Что касается компании "Флюгцойгбау Фридрихсхафен", то она была основана в 1913 г.; в конце следующего года появилась модель ФФ.29, спроектированная инженером Теодором Кобером (Flugzeugbau Friedrichshafen GmbH; Theodor Kober) и давшая затем рождение серии аппаратов марки ФФ.33, чья восьмая модификация реализовалась в 45 машинах (производилась с марта 1916 г.).

E.Hauke, W.Schroeder, B.Totschinger Die Flugzeuge der k.u.k. Luftfahrtruppe und Seeflieger 1914-1918

Kampfflugboote
K 149 Type Friedrichshafen FF 33H (Schwimmerflugzeug) Bz 150

Журнал Flight

Flight, October 16, 1919.


SOME FRIEDRICHSHAFEN "MILESTONES"

   PROBABLY no other German aircraft firm can show such a series of seaplanes as that produced by the Friedrichshafen Aircraft Works (Flugzeugbau Friedrichshafen) during the War, and for this reason a brief reference to the various types, illustrated by photographs, may not be without interest to readers of FLIGHT. The illustrations have been published in Flugsport, and the following is a translation of the descriptive matter accompanying the photographs :-
   "The Friedrichshafen Aircraft Works is the oldest German firm which has devoted its energies almost exclusively to the production of seaplanes. The firm was founded in 1912 and has produced a great number of seaplane types, under the efficient leadership of its founder and managing director, Dipl. Ing. Theodor Kober, who has been ably supported by his associates, in close co-operation with the Naval authorities and with various scientific institutions. The main sphere of activity of the firm was the construction, testing, and quantity production of seaworthy single-engined seaplanes of the types used by the German Navy for reconnaissance flights over the North Sea and the Baltic. That the firm was successful in this is proved by the fact that they have been able to supply practically all the requirements of the German Navy, and that a number of other firms have built their machines under licence. Among these may be mentioned the Luftfahrzeug Gesellschaft, the Sablatnig Aircraft Works, the Gothaer Waggonfabrik and the Warnemunde Aircraft Works. As the seaworthiness of a machine depends not only on the right shape of float, but also upon the strength of the floats and undercarriage, on the correct amount of buoyancy and on controllability when alighting, it will be seen what an abundance of experience has to be collected in order to fulfil the specifications for a seaworthy seaplane. A large proportion of the experiments was formed by tests on floats, of which over 100 types were produced. The F.F. machines, which have been well proved during the War, are all of the twin-float type, although before the War single-float machines and flying boats were also tried.
   "One object of the experiments was, among other things, to determine the number and placing of steps which best suited the different types of machines for starting and landing, and what float shape gave the best results for taxying. At the same time the floats should combine small air resistance and great rigidity with small weight, while the most suitable, strongest, and lightest construction of float details also required much work and very many experiments. The following are the most important types of seaplanes produced by the Friedrichshafen Aircraft Works :-

"The F.F. 29
   is a bomber with a 120 h.p. Mercedes engine (Fig. 1). The main floats are comparatively short, and a tail float is therefore fitted under the stern of the fuselage. The radiator is placed above the engine, and the exhaust pipes are passed under the lower plane. The pilot occupies the rear seat, while the observer sits in front, where are also the bomb releases. The petrol gravity tank is hung on the cabane struts.

"The F.F. 33,
   which is shown in Fig. 3, was fitted with a 120 h.p. Mercedes engine. It was a bomber of very similar design to the type F.F. 29, except for the floats, which were of considerably different shape.

"The F.F. 33B
   was designed for reconnaissance and had a 160 h.p. Maybach engine (Fig. 4). It was similar to the 29 and 33 types in general design, but the pilot sat in front, the observer occupying the rear seat where was mounted on a gun ring a machine gun by means of which he could fend off attacks. The radiator is in two halves, mounted on each side of the fuselage. While the floats of the F.F. 31 were provided with a Vee bottom nose, those of the F.F. 33B had a Vee bottom at the heel, and were flat-bottomed in front.

"The F.F. 33E,
   shown in Figs. 5 and 6, was used for bombing and reconnaissance, with and without wireless. In general arrangement it is similar to the 29 and 33 types. While the first machine of this type still retained the tail float (see inset Fig. 5) later machines were found not to require this on account of the long main floats with which they were fitted. The radiator was mounted on the leading edge of the top plane. Generally speaking, the fuselage, wing bracing, wings and ailerons were designed to give good aerodynamic efficiency.

"The F.F. 33F,
   shown in Fig. 7, was a development of the 33. It was, however, designed as a fighter, and was probably the first to be successfully employed by the German Navy in various theatres of war. The wing area was considerably reduced, which resulted in greater manoeuvrability. The pilot sat in front, and the observer, who was provided with a machine gun mounted on a gun ring, occupied the rear seat. In addition to the substitution of the smaller wings, with only two pairs of struts on each side, this machine was altered later on by being fitted with a shorter and better stream line fuselage.

"The F.F. 33H,
   which is shown in Figs. 8 and 9, was a development of the 33F. The fuselage, which was much shorter, was provided with a fin below as well as above, and the ailerons were redesigned to give smaller resistance. The radiator was built in flush with the top plane, which also contained the petrol gravity tank. The floats were also redesigned to give smaller air resistance. A great improvement in this machine was the incorporation of horizontal struts between the floats instead of cable, so that it was possible for the gunner to fire forward, between the inner pair of inter-plane struts and the propeller tips, since any damage accidentally done to the wing bracing in the inner bay was of minor importance as the load would be taken by the float tubes.

"The F.F. 33J.
   "This type was fitted with a 150 h.p. Benz engine, and was used as a reconnaissance machine, fitted with wireless. It has been extremely successful, and has given excellent results during the War. The 33 J (Figs. 10 and 11) is a direct descendant of the 33E. It is particularly seaworthy, is easy to fly, and very reliable, even for long-duration work. This machine is the first seaplane to be used successfully on all the seas of the world, and was used as a ship's 'plane on the Wolf. The main specification of the F.F. 33J is as follows: Weight, empty and without water, 2,300 lbs.; load, 1,185 lbs., total weight, 3,485 lbs.; length overall, 34 ft.; span, 55 ft.; float capacity, 61 cu. ft.; speed, 71-77.5 m.p.h. according to load; speed when taking off, 50 m.p.h.; climb to 4,950 ft. in 25 mins.; duration, 5 hours. This type is, so to speak, unbeaten in any theatre of war, as it was purely for military reasons that the 33J was supplanted by machines of 200 h.p. Owing to its proved capabilities the type was retained as a practice and school machine, in which form it was known as

"the F.F. 33S.
   "During the last years of the War practically all the German seaplane pilots were trained on this type (Fig. 12), and nothing more need, therefore, be said about its utility as a practice and school machine.

"The F.F. 33L.
   "This machine, which is shown in Figs. 13 and 14, is a further development of the 33H. It is fitted with 150 h.p. Benz or Mercedes engines. It formed a very happy compromise between the demands for seaworthiness and for performance. In accordance with its use as a fighter the 33L possesses great manoeuvrability, and is very seaworthy in any sea up to a rougness degree of 3. It is easy and comfortable to fly. Its main characteristics are: Weight, empty and without water, 2,070 lbs.; load, 1,045 lbs.; total weight, 3,115 lbs.; length overall, 30 ft.; span, 43 ft. 6 ins.; float capacity, 49 cu. ft.; horizontal speed, 80 to 86 m.p.h.; climb, 6,600 ft. in 30 mins; duration, 3 1/2 hours. This machine was equipped with one movable and one fixed machine gun, or one movable gun and a wireless outfit.


Flight, October 23, 1919.

SOME FRIEDRICHSHAFEN "MILESTONES"

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   "As a result of the very extensive experience of seaplane construction for War purposes, the Friedrichshafen aircraft works on Lake Constance and its branch factory at Warnemunde are in a position to, and are making every effort to, take up the construction of seaplanes for commercial purposes. As the firm has up till now chiefly devoted its energies to the construction of seaworthy seaplanes, it will be seen that it is in a better position than many other firms to construct seaworthy commercial and sporting seaplanes of all types. Especially suitable for this purpose would be the types which have proved themselves during the war, such as F.F. 49C, 33J(S), 33L, 41A, and 64. The type F.F. 49C is, it will be seen from the particulars given above, especially suitable for commercial work. The useful load of 1,430 lbs. may be divided up in different ways, according to the purpose for which the machine is intended, between crew, fuel passengers and mail. For instance, with sufficient fuel for 3 1/2 hours over 600 lbs. of useful load could be carried. For passenger carrying it would be easy to provide seating accommodation, either open or closed, enabling the machine to carry two or possibly three passengers in addition to the pilot.
   "Seaworthiness means safety. Safety is one of the chief considerations for a commercial aeroplane. Since the seaworthiness of this type has never, in spite of the greatest efforts, been beaten by the machines of any other firm, it would appear that also in post-war competition it will be one of the most suitable types and difficult to beat. Much the same may be said about the lower-powered machines FF. 33J, F.F. 33S and F.F. 64. Especially would the latter machine offer great advantages for commercial work to ship-owners for carrying on board as a ship's 'plane. For instance, it would be possible without going into port, or in other words without any appreciable loss of time, to put ashore or to take on board single passengers or mail. Or, before arriving at the port of destination an officer could be sent ashore in the machine with the ship's papers, thus not only saving time but possibly also making a considerable profit on goods carried through being first in. Also the passenger who is in a hurry can be sent on ahead in the machine, thus shortening his time of crossing by as much as 10 hours. On the other hand, the machine can fetch mail from ashore so that the mail can be on board the ship several hours before she reaches port. The machine can be employed to assist in navigation on approaching the coast in bad weather, and it can also be utilised for flying ahead of the ship, spotting for floating mines. In case of accident it may possibly be used for obtaining assistance quickly. Also from the land, the machine can be used with advantage. For instance, a merchant could be flown out to meet the incoming ship, which is carrying an agent, so that all the business could be transacted by the time the ship arrived in port, thus beating the competitors who have remained ashore. For use by salvage companies it would be possible to use the seaplane for taking an engineer to the place of the stranding in the shortest possible time, where he could photograph the stranded ship and even, if the sea is not too rough, alight and go on board the wrecked ship, so that the salvage contract could be completed before a competitor could arrive by steamer in the ordinary way. F.F. 33L is very suitable for practice flying for young pilots, and would make a good sporting machine. It is light and very comfortable to fly and requires little storage space, while being easy to dismantle and erect. All of which are qualities that make it specially suitable as a sporting machine for the private owner.
   "If it is a question of carrying relatively great loads at lower speeds, a machine similar to the type F.F. 41A or to the type F.F. 33, with two 260 h.p. Mercedes engines, would be suitable."