Without a doubt the undercarriage has always been ~ quite literally ~ the Achilles heel when it comes to the design, but the one thing we learned from the test-flights back in December at Llanbedr was that cross-bars (or lateral stabilisers) proved to be quite unnecessary. In fact it was they that broke free during one heavy landing and took out all four of the lower props... precisely what they were supposed to be there to prevent.
Short story long however I've gone for a relatively conventional pair of skids and left them aligned with the arms of the drone. There are operational reasons for doing so in so far as it makes carrying the vehicle altogether easier, and looking ahead to a scaled up version, altogether easier to get in and out of whilst providing for the best possible view. At the same time, raising the lower quad has improved the propeller clearance over the previous prototype, which again removes the need for lateral stabilisers.
For the techies out there the diagonal measure between the motor axes is 1.40 metres and the weight including the lower battery set is around 35 kilos or 78 pounds without the dummy onboard ~ he weighing a further four kilos. The accommodation is two feet tall, such that the model is the best part of two-thirds scale.
The lower quad will provide the greater portion of the lift ~ for which Phil already has an Arduino program to suit ~ and the motors are addressed directly by an associated battery-pack. The upper quad will be conventionally wired and you see from the wing-nuts that it is removable such that it can be tested independently as a regular drone that falls within the regulatory weight-limit.
Remains to be seen whether it all works to spec... but it's the taking part that counts.