Here my 2 cent:
If you really want to discuss efficiency, tailed designs are better. They need less wing area to carry the same weight, and you have an excelent performance with flaps, for short, easier and safer landing and takeoff. Less wing area means less drag, thus more efficiency. The flying wing planforms have an Coeficient of lift no better than 0.8 and tailed designs has more than 1.2. It means tailed designs carry more weight to drag, and are able to fly in a wider speed envelope. No wonder why all pylon racers are tailed. The flying wing Dynamic Soaring speed records are less than the half of the tailed designs. One of the biggest issues with flying wings is that when you pull up elevator, the wing's sections becomes reflexed, thus you lose a lot of your coeficient of lift. When you most need lift, the elevator kills it. Ok, solve it with more wing area. That comes with more drag.
Then, why many people use flying wings? As said before, wings have the folowing advantages, important for UASs:
1 - way easier to transport, with less parts, less volume and less fragile parts (as a tail, for example)
2 - crash resistant - most of the UASs customers don't have good flying skills, if any. Landing an airplane weighting over 3-4 kilograms without a large landing track isn't that easy. It is much easier letting the wing land itself in circles (like the sensefly) over grass or cropfield. If you are to buy a mapping UAS for, let's say, between US$15-70 thousand dollars, you want something that won't be destroyed on a landing or failure on the first month of use. Even so, I've heard many light and safe sense-flys having the motor mount ripped off on landings.
3 - safer to users etc. - the rear-mounting of the motor, and the lack of pinpointing nose means less danger in case of crash, both to people and property. Wings have more impact area, thus less damage to people and property.
I'm a flying wings man, I've built many sweepback (like zagis) designs, small and big, and also planks, as gliders and powered models. A very "clean" flying wing will have very small drag. In my experience, planks carry much more weight, and are much safer on stalls. BUT they require much finer CG adjustment, and are less yaw-stable on slow speeds than zagis.
But for carrying payload, I still prefer tailed designs: lower the flaps 30 degrees, you have a very slow and sweet landing (you must be experienced with rudder control for the aproach, or you may experience tip-stall, and remember that with flaps on, drag skyrockets, then you need more throttle or more descent). This also lets you land in small places, with a shorter and steeper landing aproach, and takeoff and climb in shorter spaces, as well as faster.
There is another advantage of the use of flaps: if you use tension hinges, or top hinges, you can deflect flaps at 80-90 degrees down, working as brakes. Take a look at F3J and F3K ladings with full flaps. On those light designs, I've seen 45-degree down pitch landing aproaches, without speeding up, than hand catching. Ok, with UASs that won't happen, but you can aproach landing in a very steep angle, slowly, than flare. No flying wing will do it, although some swept back wings may have flaps, they are functional only at the center section of the wing, not full span flaperons, like the examples above.
But if I would develop a UAS for non-experienced pilots, I'd definitely go with a flying wing.
I like the looks of Maja, just very expensive to get it in South Africa.
Any airframe with a tailplane, or canard, is going to be easier, and more forgiving than a wing only design.
I've never seen one flying, but it looks easy to fly, stable, crash-resistant and very practical. But... it looks very draggy. I don't have the figures, but I don't think it would be a range winner. I don't think it was designed for it either. The rear engine is a smart choice, but it becomes noisy where it was placed. If it were in front of the fin, would be as protected and more silent.
Dwgsparky, I'd like to talk to you about your X5 setup if you don't mind. I've sent you a request. :)
Look at the X-UAV Talon.
Definitely NOT "Toy-Looking", and a wing extension kit is forthcoming, carry more payload.
I've only flown mine in manual and STAB so far, and have been pleasantly surprised by it's handling and performance.
And by being EPP, easily repaired, well, small dings, in the field.
And being "tailed", one probably could modify it for Flaps.
Just my 2 cents......
First of all, let me introduce myself because this is my first post on this forums. I'm the CEO of Novadrone. We design and create drones for civil applications, with them we provide photogrammetry and remote sensing services for several sectors like civil engineering, forestry or agriculture, mainly in South America.
Secondly, let me thanks to all the open source community, because we have done all our flight tests and systems development with APM:Plane.
On the topic, I would add two points. The first one is about efficiency. Talking about professional or commercial drones it is not so easy to find a commercial drone based in a flying wing most efficient (in Ha surveyed/flight time) than the Aeromapper from Aeromao (very good work Mauricio!) or our Nomad 300 with the same payload. You can use the trimble flight calculator to compare.
This same point is related to security. Statistically, in all the civil aviation history, more than 60% of accidents occured in the take-off or landing stage. If you fly with Trimble you need more flights to survey the same area than with Aeromapper or our Nomad. More flights, more take-off and landings, more risks...
Another point is about the term "rugged". When I think in rugged equipment for professionals, what it come to my mind is a Trimble GPS (it could be falling, you can pull it concrete, water, a hammer... and it will continue running). When I see a glider manufactured in kevlar and carbon fiber, for me it is near to this concept of "rugged" than EPO/EPP flying wings... them are easy to repair, but... are rugged?.
René Hello and thank you to revive this thread.
Compared with all the points mentioned above, an important factor is the price. It is true that UAVs made of carbon or composite are probably strongest, but most UAVs manufactured in EPO / EPP are less expensive in case of crash and still strong enough. The MAJA is a very good UAV for the price, with an endurance of about 1h and easy to repair. At flying height of 120m, it is possible to have about 500ha of survey.
René, you can contact me by private message if you have some interesting options to offer.
If people have news on the development of UAV for surveying or observation, please, continue the discussion. The craze is becoming greater.