Are there any glider designs, historic or modern, which do not have a
central stick but instead use a yoke, sidestick, ...?
The Schreder HP-18 sailplane, offered as a kit to homebuilders, was designed with a sidestick. I've seen one "in the flesh". Some have now been converted to a central stick, and some were originally built that way.
One can easily see why a sidestick could be an advantage in a sailplane with a very slender cockpit, with the pilot seated in a prone position-- there would be less of an issue with the pilot's legs limiting the stick travel-- but there are some ergonomic disadvantages as well.
The Applebay Zuni sailplane also featured a sidestick. In this glider, the sidestick's fore-and-aft-motion was accomplished by sliding rather than by pivoting (the same may have been true of the HP-18's sidestick), and
the "breakout" force or static friction that needed to be overcome to move the stick in the pitch direction was rather high. This made it more difficult to control the glider at high airspeed-- the pilot could accidentally impose a high G-load when intending to only make a small input-- which may have contributed to a fatal accident.1
"Shifting gears" a bit, ultralight sailplanes that are designed to be foot launchable are usually equipped with sidesticks. The necessity for the pilots legs to be able to hang out the bottom of the aircraft makes a sidestick much more logical choice than a center stick. Many of these aircraft may also be aerotowed, utilizing wheels rather than the pilots legs, and thus are functionally equivalent to more conventional sailplanes. Motorized self-launching versions of many these aircraft also exist (again utilizing wheels rather than the pilot's legs for landing gear), and retain the sidestick configuration. Examples of foot-launchable ultralight sailplanes include the Aerianne Swift and its Bright Star predecessors, the Bright Star Millenium, and the Ruppert Archaeopteryx.
Another class of gliders that usually have sidesticks are those where the pilot flies from a prone position. Historical examples include the wings of the Horten brothers, several of which were flown in soaring competitions.
A modern example that would fit the description of a "recreational glider" is the ATOS "Cage" ultralight sailplane. The "Cage" evolved from the line of ATOS rigid-wing hang gliders in which the pilot is suspended prone below the wing with his hands on a triangular "control frame". The "Cage" uses wings from the "ATOS" hang glider series, but moves the pilot up into an enclosed fuselage between the wings, while retaining the prone position.
As for control yokes-- in modern high-performance sailplanes, where the pilot is seated in a semi-recumbent position in a slender fuselage, space is at a premium. A control yoke takes up more space than a control stick, and so a control stick is the better design choice.
- Source-- anecdotal information from long-time sailplane pilot familiar with the incident. The accident is is also mentioned-- with no cause offered-- in the last link below.
Article on Schreder HP-18 in National Soaring Museum collection (mentions side-mounted control stick)
Wikipedia entry on Schreder HP-18 sailplane (mentions side-mounted control stick)
Link to a center-stick conversion kit for Schreder HP-18 sailplane
Link to an interesting article about a highly modified HP-18
Wikipedia entry on Applebay Zuni and Zuni 2 sailplanes (mentions side-mounted control stick on Zuni, and notes that it was replaced with a center stick on the Zuni 2 "to remove unwanted roll during high g manoeuvres".
Page on Applebay Zuni and Zuni 2 sailplanes from on-line tour of National Air and Space Museum Garber facility
Wikipedia entry on Aerianne Swift foot-launchable ultralight sailplane
Webpage for Aerianne company (navigate to "Swift Aircrafts")
"Hang Gliding Wings Bible" entry for Bright Star Millenium foot-launchable ultralight sailplane
Webpage for Ruppert Archaeopteryx foot-launchable ultralight sailplane
Wikipedia entry on the Horten brothers
Link to discussion forum (in German) on ATOS "Cage" ultralight sailplane. Some photos are included.