What are the disadvantages of a tailless ultralight design?
When we designed the SB-13, we also thought that it's not so much different from a regular layout. Boy, were we wrong.

It starts with ground handling: Regular aircraft have some distance between front and main wheels, and even more between main wheels and tail skid in taildraggers. This makes them fairly stable in pitch on uneven surfaces. When both wheels are close together because there is little of a fuselage to space them apart, every bump on a grass field translates into heavy pitching. This is annoying.

It gets worse once you lift off: The little pitch damping (now I am talking of the aerodynamic sort) means that every gust makes the tailless aircraft enter into a noticeable short-period mode. This is normally so much damped that the pilot doesn't even notice. In a tailless plane the damping is just enough to stop the motion once a considerable change in pitch has happened. Of course, the pilot will try to steer against it, but with the unavoidable delay of a human in the control loop. That means the counter action will now make the aircraft pitch against the initial motion just when natural stability does the same, so an overshoot follows. Either the pilot suppresses the learned reflex of actively stopping the pitch motion or a pilot induced oscillation follows. This is even more annoying.

So much for the annoying stuff. The outright dangerous would be:


coupling between fast period mode and wing bending. Flutter at low speed is the consequence.
Nasty stall characteristics once the combination of sweepback and aspect ratio surpasses a certain threshold. For 20° sweep this would be an aspect ratio bigger than 7.


You are right about the larger wing area, but this actually helps to make the spar lighter since there is more height to place it in. Unless you need to stiffen the spar in order to shift its bending eigenfrequency above that of the fast period mode in your allowed speed range (plus 20% safety margin).