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I was just curious as to how you would make a glider glide in a circular pattern ( or helical ).

Will there be a large difference when considering a conventional glider vs a delta wing glider?

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Assuming there is no wind, a circular pattern is most easily achieved by flying a constant speed and a constant bank angle. Maintain coordinated flight (no skidding, no slipping). There is no difference in turn dynamics between a conventional glider vs a delta wing glider.

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A conventional 360 turn can be flown the same way in a powered airplane and glider: a gentle bank towards the turn, using rudder to maintain coordinated flight.

However, the purpose of a glider circling is often to catch a thermal (i.e. lifting air). In order to maximize the lifting force, a glider pilot might keep the wings level and use rudder to turn, a technique that is unique to gliders.

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    $\begingroup$ "In order to maximize the lifting force, a glider pilot might keep the wings level and use rudder to turn, a technique that is unique to gliders." – How does that work? Surely your goal in a thermal is to minimize your sink rate, and surely the way to minimize your sink rate is to stay coordinated. Maybe I should post a question about this. $\endgroup$
    – Tanner Swett
    Dec 2, 2019 at 11:38
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    $\begingroup$ In basic glider training, I was taught to remain coordinated when circling in a thermal. I don't know if a different technique is used by experienced pilots, but for me the student, the instructor insisted on the yaw string being aimed at my nose. Circling in a thermal is done pretty close to stall speed, and being uncoordinated would increase the risk of a stall/spin, so it seems like a good idea. $\endgroup$
    – Wayne Conrad
    Dec 2, 2019 at 14:18
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Delta gliders have a unique way of turning amazingly similar to the wing warping technique attempted in the early days of flight, using DRAG differential to yaw the aircraft.

This is the result of the differential of sweep angle with a change in relative wind, between the inside and outside wing. Elevons are used to roll the plane to its bank angle. The resultant sideways motion creates more drag on the inside wing, more than the "adverse yaw" created by the elevon deflection. The plane will turn without a rudder. Examples of rudderless deltas include hang gliders (weight shift) and flying wings (elevons).

Straight winged gliders do not create sufficient yaw drag differential when rolled, in fact, the ailerons will tend to yaw it in the opposite direction, hence the need for rudder input.

Conceptually, the rudder is the inside wing for a delta, and the tail for a straight winged aircraft, with many possibilities, including spoilers, in between, depending on your design style.

The large trailing portion of the delta also contributes to the turn.

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  • $\begingroup$ Yaw from differential drag isn't unique to deltas, btw. It's also done by the spoilers of the B-52. $\endgroup$
    – Camille Goudeseune
    Dec 2, 2019 at 16:24

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