written by Jack Stockford

The Zugvogel IIIa, which first flew in 1957, was developed via the Zugvogel II from the Zugvogel I, Rudolph Kaiser’s fifth design. The design was developed from the Zugvogel I by Egon Scheibe, with the elimination of the forward sweep on the wings and the inclusion of a fixed main wheel, replacing the droppable dolly. The name Zugvogel is German for migratory-bird, an apt name for any high performance, ‘open-class’ sailplane.

Span 17m
Length 7.1m
Height 1.7m
Fuselage width 0.6m
Wing Area 14.5m
Aspect Ratio 20
Dihedral 2.5º
Wing profile NACA 632-616/614
Empty weight 245kg
Max. Load 120kg
All up weight 365kg
Wing loading 25.2kg/m2
Stress Group 8

Best Glide Angle

1:35 at 43 knots

Min. Sink 0.62m/s at 37 knots
Min. Speed 31 knots

Max. Speeds:

Still air
108 knots
Rough air
76 knots
76 knots
54 knots

The technical description included on this page gives a good over-view of the Zugvogel IIIa glider. The same detail will not be repeated again.

The Zugvogel IIIa was developed further into the developed the Zugvogel IIIb, one of the primary differences being a lowering of the wing on the fuselage, reducing the cross section of the fuselage. This in turn lead to the standard class SF-27 or Zugvogel V.

Additional information regarding the Zugvogel series of gliders may be found in Martin Simon’s books “Sailplanes 1945 – 1965” (Zugvogels I – IIIb) and “Sailplanes 1965 – 2000” (Zugvogel V or SF-27m).

G-EEBS “Schwarzhornfalke”

Zugvogel IIIa Wk. Nr. 1054, registered ‘D-8363’ was initially purchased for club use by the Fliegergruppe Waldstetten in late 1960. The name “Schwarzhornfalke” (directly translated as black-peak-falcon but more poetically as Black Mountain Hawk) was given to the glider at that time, being at least the second glider based at the club to have had the name. (The English tongue unfortunately struggles with both Zugvogel and Schwarzhornfalke, the glider having acquired the nick-name cornflake later in it’s life!) From Germany the glider then moved to the Luxembourg club “CLVV” (Cercle Luxembourgeois de Vol à Voile) in 1975 where it was registered as ‘LX-CAF’ before purchased by a member of the Kent Gliding Club in 1979 and given the tri-graph ‘EBS’. The glider was flown at Challock for many years until purchased by the author and taken to the North Wales Gliding Club (via the 2010 International Rally) where it is now based. Whilst at Challock the aircraft was recovered to a very high standard in a near identical scheme to the original. As luck would have it, Volkswagen Brilliant Orange is a good match for touching up any scuff marks!

“Schwarzhornfalke in the early days at Waldstetten”. Source: TBD

Notes from the cockpit

Before getting into the glider it must first be rigged. With a two-piece, 17m wingspan the individual wings are not light. Rigging is definitely a three person affair. The glider rigs easily though despite the weight and the wing controls connect similarly to all Kaiser designed aircraft of that era. The elevator connection is made through a small, hand-sized hatch on the port side of the fuselage below the tailplane and requires balancing the elevator on one’s head and a good sense of touch.

Climbing into the Zugvogel for the first time it’s noticeable how deep the cockpit is compared to, say, an ASK-18. At 6’4¾“ tall I am above average height but even so only my head appears above the large GRP moulded forward fuselage shell. The cockpit is generously sized however (similar to the oft recognised large cockpit equipped Skylark series) and there’s plenty of room to stretch out and get comfortable. The controls are of a very conventional layout for a glider of this era and despite the relatively small, removable canopy the instruments are fully visible.

Winch launching is straight forward and the glider does seem to launch higher on its standard blue Tost weak-link on any given day than most other gliders of this type. Perhaps this is pole bending on my behalf, perhaps just warped perceptions. At 17m span, the wooden wings do tend to bend a fair amount “on the wire” especially with the stick in your lap.

“Schwarzhornfalke early on a winch launch”. Source: Unknown (WWW)

Once airbourne the Zugvogel IIIa is a very well behaved glider with nothing extraordinary in the way that it feels or handles. The performance is good for a glider of this vintage, being directly comparable in the cruise at circa 45 knots to the aforementioned ASK-18, which of course is some 10 years its junior. Cockpit noise is naturally aircraft dependant but with the smooth glass nose fairing and faired canopy, every effort was made at the design stage to reduce the sources of drag that create the noise. The predominant source seems to be the rectangular cut-outs in the fuselage just aft of the main spar locations: the noise from these locations being easily got rid of with tape.

One area where the glider blots its copy book is perhaps when turning where directionally it seems not quite as steady as, say, the ASK-18. This seems to manifest itself in a gentle yawing once in the turn, most noticeable when thermalling. I was embarrassed by this to begin with but after speaking to other Zugvogel pilots it seems that it’s a relatively normal quirk of the glider and not down to pilot aptitude. It doesn’t happen to me in a K-18. Honest.

Landing is, once again, straight forward. The airbrakes are effective enough to be satisfactory despite the dive-bomber style holes in them (presumably to reduce turbulent airflow over the tailplane) and the forward visibility is good.

“Two Migratory Birds, resting”. Source: J Stockford

“Schwarhornfalke formating on a T-21. Note the liberal amount of air-brake required”. Source: A. Gilles.