TGoodwin

I was reading the latest issue of RCJI and noticed in the article on the flight data recorder that the plane pulled 6.5G's out of a dive. Now if my plane weighs 6lbs and it pulls a 6.5G turn then now the plane weight is 39lbs! The question I have is how is that weight distributed? How would I test a prototype to be sure it could withstand such a force on the airframe? Can I block the plane up by the wings and set a 33lb weight on it?

Thanks Ted

greenboot

My Feedback: (1)

The weight would be evenly distributed. For example a 1 lb motor becomes 6 lbs. Battery is 6 times heavier. Same for servos and everything else. The "lift" force which supports this weight must be evenly distributed along the wing.

You can't just pile a bunch of weight on the plane to check it.

Tom

Tall Paul

In full-scale testing, the load is distributed, say along the span.
In the old timey days sand bags were used, with the amount of weight depending on the position on the span.
Nowadays hydraulic cylinders programmed to vary the loads are used.
On models, unless you're designing to the gnat's ass minimum structure, it's not worth the effort to do, as most structures are seriously too strong anyway!
If your previous model built in a particular manner hasn't broken in flight when flown the way you fly, the next one probably won't either.
.
PJB's Seriously Aeronautical Stuff:
http://home.earthlink.net/~pjburke1/aindex.html
Sparky Paul:
http://www.angelfire.com/indie/aerostuff

mulligan

Our models pull many more Gs than full-scales do. Some are designed for G loadings well over 30, but 10 seems like an average number for anything non-trainer. If you want to test your wing center joint or wing to fuse attachment, you can put the total load on the fuse and support the wing below the Mean Aerodynamic Chord (MAC). It is virtually impossible to test the wing or fuse structures completely, because of the need to not only distribute the load, but also the supports along the span of the wing, stab, and fuse.

- George