The primary glider originated in Germany in the early 1920s, when that country was in economic chaos. To most who wanted to be pilots, powered flying schools were far too costly. There were a few two-seat gliders, but they were not cheap. It was found possible to teach beginners ab initio by a careful series of exercises in simple one-seat gliders, and the methods were developed under the auspices of the RRG. Alexander Lippisch designed the Zogling (Pupil), which became the standard primary trainer. It was a monoplane with a rectangular wing spanning 10m. The fuselage, if it could be so called, was an A shaped frame forming a kingpost to carry the wing, with anchorage points for flying and landing wires and a gate-like extension to the tail, which was also wire braced. The seat and controls were mounted on a solid keel. It was common for the open 'primary' to be fitted with a light nacelle around the cockpit which reduced drag slightly and allowed it to be termed a 'secondary'. Slope soaring flights were possible, though when the wind was strong enough to give sufficient lift, the air was also usually too turbulent for the Zogling to be flown safely. Plans were distributed to gliding clubs and manufacturers produced Zoglings, or modified versions, for sale.
A variation of the design was developed at the behest of Wolf Hirth. Instead of the wooden frame aft of the wing, a simpler structure of four steel tubes
carried the tail. Drawings for this type found their way to the USA in 1929, where the National Glider Association (NGA) was establishing itself. When the
EGA was founded later in the same year, copies of these blueprints were sent back across the Atlantic as an act of goodwill by the NGA. The London Gliding
Club obtained a set. R. F. Dagnall, founder of the RFD Company, already well established in building balloons and with experience in airship construction, offered to build a glider for the London Gliding Club, and he was given these German/American plans of the modified Zogling to work with. Dagnall made some detailed changes, altering all measurements from the metric system to the Imperial, and produced what he called the Dagling. The prototype was flown by London Gliding Club members on 16 March 1930 at Guildford, and was taken at once to Aldbury, near Tring in Buckinghamshire, for further operations by the club. About 28 RFD Daglings were produced during the following months, and all similar gliders built in Britain after this were called Daglings, irrespective of their origin. By 1932, however, Dagnall was heavily involved in government contract work, so he handed over the glider business to the British Aircraft Company (BAG), which had its own primary glider design on the market as well as some good intermediate sailplanes and a promising two-seater, the BAG VII. Unfortunately in May 1933 Lowe Wylde, the founder and chief designer, was killed when flying the Pianette, a powered version of the BAG VII. Robert Kronfeld, the famous soaring pilot, left his native Austria and took Lowe Wylde's place, and became interested in developing the Drone powered light aeroplane. Glider building by BAG ceased.
The changed directions of RFD and BAC gave Fred Slingsby an opportunity he was quick to seize. Production of primary gliders virtually identical to the
Dagling began in Scarborough in 1933 and continued after the move to Kirbymoorside. Sixty-seven were built before the outbreak of the Second World War. (A
few more Daglings were built by other companies, some even in post war years.) Slingsby would almost certainly have been unable to continue without the
fairly steady sales of this type and the repair business that resulted. The twin wing spars were solid timber planks set on edge and the ribs, all alike, were threaded over the spars before gluing. The extreme leading edge was covered with a fairing of plywood, the rest with fabric. Torsional resistance was provided by internal diagonal struts and wires. The A frame was made of solid timbers faced with plywood above the wing. The keel, shod with a strip of sheet steel and with no springing whatever, was similar, with strong external longitudinal stiffeners. The seat, a piece of heavy plywood with minimal hip and back support, was rigidly mounted on stout brackets above the keel with space below for the steel torque tube to a bell-crank behind the seat, operating the aileron cables. The tailplane, larger than that of the Zogling, was bolted at the ends directly to the steel tubular supports. The fin, in two separate pieces, was mounted on the centre of the tailplane with more wire bracing to keep it upright. The control surfaces were mounted in the simplest manner, with wide gaps along the hinge lines.
Solo glider training involved a graded series of exercises, closely supervised by an instructor. Fritz Stamer and Lippisch of the RRG outlined the process in lectures and in a book which was published in translation in Britain in 1930. To start, ground slides and low hops would be made. The bungee, a V of rubber rope, was laid out with the steel ring at the apex hooked on to the glider's open hook at the extreme nose. Ropes with large knots at intervals were attached at the ends of the V for the launching crew to hold, and one or more persons would sit under the glider's tail to hold it back. All of the bungee crew would be trainees themselves, and so would learn something from watching others as well as from their own efforts when their turn came.
The instructor, after briefing the pilot, gave the orders: 'Walk.... Run....', and the rubber stretched. The force of the launch was controlled by judging the right
moment to call the final command to the tail crew: 'Let go!' The glider would move forward, the ring falling off the hook as soon as the rubber tension was exhausted.
Depending on the force, the glider would either slide along the ground for a short distance or take-off and glide down the gentle incline that was used for such training. After each attempt, instructor and pupil would confer before the next trial. After perhaps three or four such starts, another pupil would take the seat and the last would go to help with the bungee. Payment, in addition to club membership fees, was in pence. As skill and confidence increased, the launches would be made stronger until hops up to several feet above ground were achieved safely with short, smooth glides and landings, after which the Dagling would be taken to a bigger hill for longer flights until a straight glide of 30sec was achieved for the A certificate. After this, the pilot would learn to make turns in both directions
and keep the glider flying for a minute, to gain the
B certificate. The C certificate, requiring a 5min soaring
flight with a safe landing, could be done in a primary
glider, but the pupil usually moved on to something
better for this.
With the development of winch launching and automobile
towing, a modified system was used. This could
be managed with a veiy small number of people, the
instructor, a winch or car driver and two or three
pupils to handle the 1 glider on the ground. The Dagling
was first given a series of extended ground slides by
being pulled along at less than flying speed. This taught
the use of ailerons and rudder quite well, though not in
a co-ordinated fashion. Some Daglings were modified
for this procedure by ha\ing most of their wing fabric
removed and being fitted with wheels. (The author's
own first 'flying' experience was on such a 'Penguin 1 .)
For the first airborne hops, the tow speed was
increased and it was then largely up to the winch or car
driver to control the situation. With a complete novice
the launch would be very gentle, and power would be
cut almost as soon as the glider left the ground. Once
this kind of hop was managed safely, the launch would
be extended, the glider flying le\-el under tow a few feet
off the ground from one side of the flying ground to the
other. After this, progress would be made by climbing
gently to some height and releasing the cable to glide
down. (By now, releasable couplings as well as the
open bungee hook were fitted to all gliders.) From this
stage it was a matter of doing higher and higher hops
with steeper climbs until turns could be managed. The
requirement of a GOsec flight to complete the 'B' usually
meant that the pupil would take a launch to several
hundred feet above the ground and make a full gliding
circuit, landing close to the take-off point. The experience
of doing a circuit in an open primary was not
easily forgotten.
That was the theory. By 1930 Fritz Stamer was the
most experienced gliding instructor in the world,
running the Wasserkuppe RRG school with an efficient
organisation, professionally staffed, with workshop
facilities and craftsmen on site to repair damaged aircraft.
The pupil was expected to stay for a whole
summer season, flying (and working on the bungee)
eveiy suitable day. According to Stamer, in 1929 there
were 269 such pupils of whom 121 completed the B
tests. The success rate after several months under
expert guidance was 45 per cent. Those presenting
themselves at the school were perhaps not always very
talented, but they were keen enough to dedicate a
season to the enterprise. The C soaring test was
achieved by 30 of the best B pilots who stayed for an
extra month; 11 per cent of the hopeful starters.
In the wholly amateur, part-time gliding clubs in
Britain and most other countries, and indeed in most
small German clubs, the RRG school's modest success
rate was not approached.
The structure of the Dagling was simple, though club
members found it difficult and frustrating to carry out
repairs. Primary gliders were built or bought, broken,
repaired, and broken again. A moderately heavy
landing could cause the landing wires to snap or
stretch, which required careful readjustments. Merely
to rig or re-rig a primary could occupy a group of inexperienced
people the best part of a morning. Overtightening
any of the turnbuckles would cause
misalignment. Worn or broken cables required perfect
splicing, which few could do. Broken spars and struts
and cracked plywood had to be repaired with accurately
made scarf joints. The tubular tail supports of
the Dagling were not often broken, but they could be
bent or torn from their mountings. Selection of materials
and quality of workmanship was no less important
for these flying machines than for any other's.
It is not known how many pupil pilots joined a club,did a few trial slides or hops and left for ever in sheer
frustration. Of the 90 clubs listed as active in Britain in
1930, barely a handful survived for a year. Slingsby s
own initially enthusiastic group at Scarborough got a
mere handful of student pilots to the A certificate and
was in dire straits before 1932. Eventually, amalgamation
with the Bradford club, which had itself absorbed
the Leeds group and seen the demise of several others in
the region, led to the formation of the Yorkshire Gliding
Club. With a first-rate soaring site at Sutton Bank, this
was one of the very few that survived and flourished.
It is also clear that many potentially good glider pilots
were scared off by the solo training system, and some
were seriously injured or killed. This continued even
into the immediate post-Second World War years, when
British clubs persisted with solo training. Despite
careful advice by the instructor, almost anything could
happen once the glider began to move. With the
Dagling's sluggish ailerons and very sensitive elevator, a
nervous trainee could pull up from what should have
been a modest low hop to 20ft or more, stall, drop a wing
and cartwheel, smashing the glider to matchwood.
Trainees airborne for the first time often felt they
had been catapulted far higher than they really were.
They knew only that the control stick should be moved
forward to come down. They often dived back from
10ft to hit the ground hard. The curved keel of the
Dagling was just the right shape to throw the nose up
again on contact, precipitating a series of violent and
very noisy bounces. The unsprung keel and rigid seat
transmitted every bump. A good many people left
gliding sites with aching backs or necks which continued
to give trouble for years afterwards. Shaken and
hurt by such experiences or even by seeing them
happen to someone else, many decided that gliding
was not for them.
More serious and even fatal injuries did happen.
When experiencing 'negative g* for the first time, as
Derek Piggott has described, an automatic reflex
response to the sensation causes some pupil pilots to
push the control stick hard forward. The moment of
transition from climbing fairly steeply on the winch
launch to gliding down in a Dagling, if done rather
clumsily, produced exactly this result. Those watching
never knew why some pupils dived vertically, or even
beyond the vertical, into the ground.
The cheapest possible training method was developed
and applied in Germany under the pressure of
financial disaster. It seems clear that if, instead of following
the RRG system, gliding organisations had
stretched their capital a little more and purchased twoseaters
with dual controls, the gliding and, more
importantly, the soaring movement, even during a
great economic depression, would have done a great
deal better. Satisfactory two-seater sailplanes did
exist, and although they were more costly in the short
term they would have been cheaper as well as more
effective over a slightly longer period. They would
have been less often broken, more pupils would have
remained in the clubs and succeeded. Income from
flying fees would have been greater. Yet, as remarked
above, it is doubtful if Slingsby Sailplanes would have
survived had there not been a steady trade in new
Daglings, Dagling spares and repairs.
A variation of the design was developed at the behest of Wolf Hirth. Instead of the wooden frame aft of the wing, a simpler structure of four steel tubes
carried the tail. Drawings for this type found their way to the USA in 1929, where the National Glider Association (NGA) was establishing itself. When the
EGA was founded later in the same year, copies of these blueprints were sent back across the Atlantic as an act of goodwill by the NGA. The London Gliding
Club obtained a set. R. F. Dagnall, founder of the RFD Company, already well established in building balloons and with experience in airship construction, offered to build a glider for the London Gliding Club, and he was given these German/American plans of the modified Zogling to work with. Dagnall made some detailed changes, altering all measurements from the metric system to the Imperial, and produced what he called the Dagling. The prototype was flown by London Gliding Club members on 16 March 1930 at Guildford, and was taken at once to Aldbury, near Tring in Buckinghamshire, for further operations by the club. About 28 RFD Daglings were produced during the following months, and all similar gliders built in Britain after this were called Daglings, irrespective of their origin. By 1932, however, Dagnall was heavily involved in government contract work, so he handed over the glider business to the British Aircraft Company (BAG), which had its own primary glider design on the market as well as some good intermediate sailplanes and a promising two-seater, the BAG VII. Unfortunately in May 1933 Lowe Wylde, the founder and chief designer, was killed when flying the Pianette, a powered version of the BAG VII. Robert Kronfeld, the famous soaring pilot, left his native Austria and took Lowe Wylde's place, and became interested in developing the Drone powered light aeroplane. Glider building by BAG ceased.
The changed directions of RFD and BAC gave Fred Slingsby an opportunity he was quick to seize. Production of primary gliders virtually identical to the
Dagling began in Scarborough in 1933 and continued after the move to Kirbymoorside. Sixty-seven were built before the outbreak of the Second World War. (A
few more Daglings were built by other companies, some even in post war years.) Slingsby would almost certainly have been unable to continue without the
fairly steady sales of this type and the repair business that resulted. The twin wing spars were solid timber planks set on edge and the ribs, all alike, were threaded over the spars before gluing. The extreme leading edge was covered with a fairing of plywood, the rest with fabric. Torsional resistance was provided by internal diagonal struts and wires. The A frame was made of solid timbers faced with plywood above the wing. The keel, shod with a strip of sheet steel and with no springing whatever, was similar, with strong external longitudinal stiffeners. The seat, a piece of heavy plywood with minimal hip and back support, was rigidly mounted on stout brackets above the keel with space below for the steel torque tube to a bell-crank behind the seat, operating the aileron cables. The tailplane, larger than that of the Zogling, was bolted at the ends directly to the steel tubular supports. The fin, in two separate pieces, was mounted on the centre of the tailplane with more wire bracing to keep it upright. The control surfaces were mounted in the simplest manner, with wide gaps along the hinge lines.
Solo glider training involved a graded series of exercises, closely supervised by an instructor. Fritz Stamer and Lippisch of the RRG outlined the process in lectures and in a book which was published in translation in Britain in 1930. To start, ground slides and low hops would be made. The bungee, a V of rubber rope, was laid out with the steel ring at the apex hooked on to the glider's open hook at the extreme nose. Ropes with large knots at intervals were attached at the ends of the V for the launching crew to hold, and one or more persons would sit under the glider's tail to hold it back. All of the bungee crew would be trainees themselves, and so would learn something from watching others as well as from their own efforts when their turn came.
The instructor, after briefing the pilot, gave the orders: 'Walk.... Run....', and the rubber stretched. The force of the launch was controlled by judging the right
moment to call the final command to the tail crew: 'Let go!' The glider would move forward, the ring falling off the hook as soon as the rubber tension was exhausted.
Depending on the force, the glider would either slide along the ground for a short distance or take-off and glide down the gentle incline that was used for such training. After each attempt, instructor and pupil would confer before the next trial. After perhaps three or four such starts, another pupil would take the seat and the last would go to help with the bungee. Payment, in addition to club membership fees, was in pence. As skill and confidence increased, the launches would be made stronger until hops up to several feet above ground were achieved safely with short, smooth glides and landings, after which the Dagling would be taken to a bigger hill for longer flights until a straight glide of 30sec was achieved for the A certificate. After this, the pilot would learn to make turns in both directions
and keep the glider flying for a minute, to gain the
B certificate. The C certificate, requiring a 5min soaring
flight with a safe landing, could be done in a primary
glider, but the pupil usually moved on to something
better for this.
With the development of winch launching and automobile
towing, a modified system was used. This could
be managed with a veiy small number of people, the
instructor, a winch or car driver and two or three
pupils to handle the 1 glider on the ground. The Dagling
was first given a series of extended ground slides by
being pulled along at less than flying speed. This taught
the use of ailerons and rudder quite well, though not in
a co-ordinated fashion. Some Daglings were modified
for this procedure by ha\ing most of their wing fabric
removed and being fitted with wheels. (The author's
own first 'flying' experience was on such a 'Penguin 1 .)
For the first airborne hops, the tow speed was
increased and it was then largely up to the winch or car
driver to control the situation. With a complete novice
the launch would be very gentle, and power would be
cut almost as soon as the glider left the ground. Once
this kind of hop was managed safely, the launch would
be extended, the glider flying le\-el under tow a few feet
off the ground from one side of the flying ground to the
other. After this, progress would be made by climbing
gently to some height and releasing the cable to glide
down. (By now, releasable couplings as well as the
open bungee hook were fitted to all gliders.) From this
stage it was a matter of doing higher and higher hops
with steeper climbs until turns could be managed. The
requirement of a GOsec flight to complete the 'B' usually
meant that the pupil would take a launch to several
hundred feet above the ground and make a full gliding
circuit, landing close to the take-off point. The experience
of doing a circuit in an open primary was not
easily forgotten.
That was the theory. By 1930 Fritz Stamer was the
most experienced gliding instructor in the world,
running the Wasserkuppe RRG school with an efficient
organisation, professionally staffed, with workshop
facilities and craftsmen on site to repair damaged aircraft.
The pupil was expected to stay for a whole
summer season, flying (and working on the bungee)
eveiy suitable day. According to Stamer, in 1929 there
were 269 such pupils of whom 121 completed the B
tests. The success rate after several months under
expert guidance was 45 per cent. Those presenting
themselves at the school were perhaps not always very
talented, but they were keen enough to dedicate a
season to the enterprise. The C soaring test was
achieved by 30 of the best B pilots who stayed for an
extra month; 11 per cent of the hopeful starters.
In the wholly amateur, part-time gliding clubs in
Britain and most other countries, and indeed in most
small German clubs, the RRG school's modest success
rate was not approached.
The structure of the Dagling was simple, though club
members found it difficult and frustrating to carry out
repairs. Primary gliders were built or bought, broken,
repaired, and broken again. A moderately heavy
landing could cause the landing wires to snap or
stretch, which required careful readjustments. Merely
to rig or re-rig a primary could occupy a group of inexperienced
people the best part of a morning. Overtightening
any of the turnbuckles would cause
misalignment. Worn or broken cables required perfect
splicing, which few could do. Broken spars and struts
and cracked plywood had to be repaired with accurately
made scarf joints. The tubular tail supports of
the Dagling were not often broken, but they could be
bent or torn from their mountings. Selection of materials
and quality of workmanship was no less important
for these flying machines than for any other's.
It is not known how many pupil pilots joined a club,did a few trial slides or hops and left for ever in sheer
frustration. Of the 90 clubs listed as active in Britain in
1930, barely a handful survived for a year. Slingsby s
own initially enthusiastic group at Scarborough got a
mere handful of student pilots to the A certificate and
was in dire straits before 1932. Eventually, amalgamation
with the Bradford club, which had itself absorbed
the Leeds group and seen the demise of several others in
the region, led to the formation of the Yorkshire Gliding
Club. With a first-rate soaring site at Sutton Bank, this
was one of the very few that survived and flourished.
It is also clear that many potentially good glider pilots
were scared off by the solo training system, and some
were seriously injured or killed. This continued even
into the immediate post-Second World War years, when
British clubs persisted with solo training. Despite
careful advice by the instructor, almost anything could
happen once the glider began to move. With the
Dagling's sluggish ailerons and very sensitive elevator, a
nervous trainee could pull up from what should have
been a modest low hop to 20ft or more, stall, drop a wing
and cartwheel, smashing the glider to matchwood.
Trainees airborne for the first time often felt they
had been catapulted far higher than they really were.
They knew only that the control stick should be moved
forward to come down. They often dived back from
10ft to hit the ground hard. The curved keel of the
Dagling was just the right shape to throw the nose up
again on contact, precipitating a series of violent and
very noisy bounces. The unsprung keel and rigid seat
transmitted every bump. A good many people left
gliding sites with aching backs or necks which continued
to give trouble for years afterwards. Shaken and
hurt by such experiences or even by seeing them
happen to someone else, many decided that gliding
was not for them.
More serious and even fatal injuries did happen.
When experiencing 'negative g* for the first time, as
Derek Piggott has described, an automatic reflex
response to the sensation causes some pupil pilots to
push the control stick hard forward. The moment of
transition from climbing fairly steeply on the winch
launch to gliding down in a Dagling, if done rather
clumsily, produced exactly this result. Those watching
never knew why some pupils dived vertically, or even
beyond the vertical, into the ground.
The cheapest possible training method was developed
and applied in Germany under the pressure of
financial disaster. It seems clear that if, instead of following
the RRG system, gliding organisations had
stretched their capital a little more and purchased twoseaters
with dual controls, the gliding and, more
importantly, the soaring movement, even during a
great economic depression, would have done a great
deal better. Satisfactory two-seater sailplanes did
exist, and although they were more costly in the short
term they would have been cheaper as well as more
effective over a slightly longer period. They would
have been less often broken, more pupils would have
remained in the clubs and succeeded. Income from
flying fees would have been greater. Yet, as remarked
above, it is doubtful if Slingsby Sailplanes would have
survived had there not been a steady trade in new
Daglings, Dagling spares and repairs.