Eggloft Duration must loft an egg (or two), return it safely, and get a really long duration. Typically, very large parachutes are used in Eggloft Duration models.
The contestant’s score is the duration of the best flight (of two possible flights). Longest duration wins.
Egglofters for altitude tend to follow the design which is an egg capsule on a small diameter body tube. Egglofters for duration are usually different. To achieve a long duration, you need a large parachute. To pack a large parachute, you need a large body tube. So egglofters for duration are typically “stocky” designs with a large body tube.
A compromise between a stocky design and an altitude design is the Two Minute Egglofter design by George Gassaway. This model uses a long conical boattail to provide an aerodynamic shape. The cone also provides a large internal volume for storing a reasonably large parachute. Protecting the parachute from the hot gas from the ejection charge can be challenging, but achievable.
One challenge of eggloft duration is to make sure you get the model back. To have a qualified flight, an egglofter must be recovered so that the egg can be checked. If a duration egglofter catches a large thermal and drifts away, the duration of this flight cannot be used.
The Courier egglofter kit by Quest has a fairly large body tube and could be a good candidate for Eggloft Duration.
ARTICLES AND PLANS
See the Eggloft Altitude page for articles and plans about egglofters, some of which might be applied to Eggloft Duration