SEN 3444

1. Auto Surface B-Electric Challenge
2. Another thought on closed loop control

 

Auto Surface B-Electric Challenge
From: Aram Schlosberg
When I defned B-electric ages ago, auto surfaces were optional in B-electric. Although I have subsequently submitted repeated rule fixes to require auto-surfaces in B-electric, all have been rebuffed. The anomaly is that E36s can be Flown the three events – E36, A and B-electric. (No AMA Flyers Fly F1S.)
To challenge Q fliers and anyone who has an auto-surface electric model with 2 or 3 LiPo batteries at the ’26 Nationals B-electric event ?own on July 20, I’m offering a beautiful small glass trophy to the highest scoring auto-surface B-electric model. There are no Joule ceilings!
(The ’26 AMA electric rules are three flights with a 7-second motor run to a 2-minute max. If clean, then two Flyoff Flights with 5-second motor runs to the same max followed by flyoff
flights with 4 -second motor runs to a 2:30 max.)

Another thought on closed loop control
From: Peter Martin
Hello SEN,

It’s been a while since I commented on open and closed loop control in SEN 3261 and 2682, but wanted to share another thought.

A variable pitch propeller hub is an open loop controller because, although it senses torque it does not control the torque, only blade angle in a fixed relationship.  However, what about the Montreal Stop in that hub?   This device also senses torque and, at a lower threshold, acts to direct the torque against the mechanical stop and cut the propeller rotation.  So it both senses and controls torque, it must be illegal closed-loop feedback, right??

Not quite, because it’s classed as a limit switch that triggers an irreversible event which breaks any loop, it’s an open-loop control.  An opposing example would be a household temperature thermostat – That is also a form of limit switch, but there are actually 2, one to cut the heat and one to turn it back on again.  In this case, it both senses and truly controls temperature, (although not very smoothly as it cycles on and off), so it’s a closed loop controller.

With the open-loop Montreal Stop in mind, this brings us back to Aram Schlosberg’s point about using an electric aircraft energy meter to stop the motor or trigger any other event.  There is an obvious analogy between a rubber model Montreal Stop triggered by low torque and an energy meter prop-stop triggered by low battery energy.  If the second case is banned for some reason, then the Montreal Stop should be banned too.  Or we allow both.

Cheers,
Peter

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