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The G force challenge!

#1
Much like the speed challenge, contestants must design or build off of some plane that already have to make it cope with its environment. It isn't just brute force like the speed challenge, because you also have to think about how much lifting surface your plane will have when pitching up and initiating the high g turn. Obviously, the plane which can take the most g force without breaking into two, smaller planes, wins.
 

SteevyT

Senior Member
#6
How would you measure the amount of Gs being applied?
Cheap multirotor flight controller with datalogging enabled would be how I would do it. Put the logs in Excel, and make a new column with =sqrt(xaxis^2 + yaxis^2 + zaxis^2) and whoever has the highest value in that column wins.
 

IFlyRCstuff

Flyer Of Many Things
#7
I would set it up so both participants must do a routine that should (in theory) destroy their plane, of course the problem of different speeds comes up, but...
 

IFlyRCstuff

Flyer Of Many Things
#9
At least reasonably close, then use a data logger of sorts to find out max gs before spliting in two. There may be rules such as no reinforcement other than glue tape and foam
 

Cyberdactyl

Misfit Multirotor Monkey
#10
Cheap multirotor flight controller with datalogging enabled would be how I would do it. Put the logs in Excel, and make a new column with =sqrt(xaxis^2 + yaxis^2 + zaxis^2) and whoever has the highest value in that column wins.
Good idea.

And are multirotors allowed in the challenge?
 
#11
Anyone have a clue what max G loads a typical flight controller can measure?
An ultralight light nimble plane might be able to exceed its capabilities easily, we're probably talking 10's of G's here and I doubt naze's and the like have that range.

So two suggestions:
1) require a minimum AUW. A heavier plane will be much harder to build to sustain high G forces. Obviously ban composite materials, allow only foam and perhaps balsa.
2) look in to loggers used by rocket enthousiasts. Something like this:
https://www.apogeerockets.com/Elect...Metrum?zenid=2cb2561126c63496933d607f1c383704

(that one can handle 70g in one axis)
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#12
Most FCB's these days use the MPU-6050 (haven't seen a newer latest-hotness IMU implemented yet on a FCB).

According to their datasheets (pdf), they are software configurable between ±2g and ±16g on binary steps. I'd expect it's set to the higher side by most FCB's, but haven't dug into any code yet to see the configuration sent. Shock tolerance is 10,000g for 0.2ms -- a pretty hard hit, and any vibe isolation should cut that out.

So no, a standard FCB won't be up to the task of logging the G-forces on a strongly aerobatic craft, but they're not designed for that -- Trying to control "level" on a multirotor at +20g with an IMU means you've got bigger problems on your hands.