Hey Brad,
Congratulations on the maiden flights! It held up a lot better than I expected from Depron wings, especially with the endurance testing provided! That graphics scheme looked even more menacing in the air!
The following is a long winded diatribe about landing any of the Mud Ducks. This is a common "hurdle" that new Duck pilots must make so I wanted to use your video as a learning tool for other Duck builders who haven't flown one yet. Your landing woes were due to a lack of applied power (or too little applied power), too much elevator, and too long of an approach. I don't think the lighter airframe was a factor (besides it slowed down a lot faster when you cut power. If you had been flying on a combustion engine, the effects would likely not have been so dramatic since the engine, even at idle would have been generating some thrust.
As with any of the Ducks flying on electric power, you have to fly them into a landing. Unless you set your throttle trim so you have thrust at the lowest stick setting, the drag from the airframe will slow the plane down extremely fast and two things will happen #1 - you lose control authority & #2 you will drop vertically as fast as your forward flight.
In the video it looks like what might have been happening was you were at what is essentially a stall for the Agri-Duck. Your Duck was essentially making a controlled “fall”. Your elevator was on the edge of ineffective because the plane was "falling" as fast as it was moving forward and the airflow over the elevator was either ineffective or in "dirty" air from the wing (judging by the angle of descent).
The next time you fly the plane to the ground and just cut the power when you’re just off the deck (or on it). One of the most common mistakes for most first time Duck pilots are the landings. After years of flying traditional models with some mass and very little drag it is second nature to most pilots to expect a plane to require a glide path and some amount of runway for roll out. Not so with the Ducks, they will just transfer their forward momentum into vertical momentum if you try to glide them. Your glide path with power off was about 45 degrees (visible when the background came into the shot), and that’s about the best you can expect without power (or stored energy). Just keep in the back of your head this: "Flaring for landing is not needed above 5 feet of altitude and keep the prop turning (some thrust) until the wheels are on the ground".
On your first landing I can see you were almost full up elevator the majority of the time (where it’s visible on the video) from at least the 3:58 minute mark until you touched down at the 4:33 minute mark (31 seconds). When the plane started acting like it was going to tip stall you let off the elevator long enough to become stable again but then you went back into the elevator each time which slowed it down too much.
On the last segment you can see how stable the plane was throughout the approach until about the 5:26 minute mark when you started using a lot of elevator and the prop was only free-wheeling (no motor sound). In the last 8 seconds (at about tree top level) the plane goes into full stall (at least full stall for a Duck) your prop even stopped spinning about 10 feet from the ground.
Since your Duck is much lighter than traditional Ducks, I'm sure there is a whole new aspect to the way it is flying but I’m sure you will benefit greatly from flying it in to a landing with power on. I hope that "crack" wasn't something too bad I heard at the end of the video.
On a related note if you lose power and have to “deadstick” it in for a landing; “dive” (not glide) at about 45 degrees toward the runway and if you can’t make the runway in 45 degrees, then pick out the smoothest patch within that angle and save your elevator and flare until you are literally just off the deck (~10’) and you will have enough energy to control it the whole way.
Greg
Electric Agri-Duck