I have read the following:
I would only like to provide a counter opinion in your thread because of your comment “You may find some flaws and your comments are welcome.”
There a several practical reasons why the Langstroth design has the entrance at the bottom. Dead bees and debris removal is one of them (that is addressed in the top link). Removal of dead bees and debris is critical to the health of the hive, and making the bees work against gravity to extract these elements seems counter productive. If you are having issues with dead bees blocking lower entrances, your lower entrances aren’t large enough.
If pests are using the brood box for nesting you can place coarse mesh on the lower entries to stop intrusion. The entire hive itself should also be lifted off the ground to prevent interference from grass/weeds and to deter other pests that attack bees (eg. cane toads in Australia). In Australia, having the hive too low to the ground can also encourage snakes to nest under the box because of the generated heat.
The primary argument I have against this approach is that the Langstroth hive is designed to ‘trap’ heat. The vertically stacked configuration results in excess heat from the brood box being trapped in the super and under the lid which assists in maintaining the hive temperature. It is for this reason that opening hives on cold days is discouraged (due to heat loss when the lid is removed). This is also one of the reasons that Warre beekeepers go to so much effort to keep boxes together when nadiring their hives. Adding a top entry this high up is going to result in hot air rising and rapidly exiting the hive through the ‘entrance’ causing more work for the bees to generate heat to keep the hive warm (this additional heat generation will cost honey).
You will notice on many hive designs that top ventilation (if/when provided), is done so in such a way that the bees are able to regulate the escape of hot air using propolis to block the ventilation ports. With an opening this size, the bees have no way of regulating the escape of hot air out the top of the hive.
You may not be able to ‘see’ the impact of heat loss by visually ‘inspecting’ the hive, so I strongly encourage anyone running this form of top entrance to capture an image of the thermal profile of the hive, especially in winter, using a FLIR or similar technology.
If there is still a need for a higher entrance, I would suggest placing it between the brood box(es) and the super(s). There are excluder designs that incorporate an additional entrance above the excluder, or in your case where you aren’t running an excluder, there are entrances that fit as a ‘shim’ between the boxes to create an additional (or primary) entrance. (here is a commercial product for exactly this purpose)