Ya, this is kinda the symptoms i'm getting on my Eagle 50. I throttle up, and it begins to shake violently at that sweet spot. I do not throttle past it because i am afraid it will tear itself apart.

As far as I have researched, ground resonance has no effect on 2 bladed rotors because of the see-saw effect, so i can't figure out why it's happening to my heli???I don't think the flybar counts as an exta blade????the 3+ blade rotors on mostrc helis,are built withlead- lag hinges which speedup or slow down the rotoron its path around the mastto compensate for the change in center of gravity after a vibration is encountered.Most helis also employ the use of landing gear or skid dampeners to mitigate the possibiliy of the initial inciting of the vibrations.

The post by rafael shows a heli getting shredded probably because (and this is just a hunch) it is a 3+ blade heli (the real Hughes 500 is a 5 blade), and he might have had a problem with his lead-lags. also, keep in mind the chinhook has two 3 blade rotors. Soooooo, I don't know quite yet if it is possible for a 2 blade to get ground resonance.....yet I am getting the symptoms(either that or it is a bent shaft) of ground resonance even when my heliis not strapped to the ground and is ready to takeoff. When I check my blade tracking, iusually just put a couple bricks on the skids to weigh it down and that worked fine.........no resonance. Then I made a booboo flying one dayand crashed and now I can't get my heli to stop shaking, therefore leading me to doubt ground resonance as a possible cause of vibration.

Feel free to critique me, as you can see by my post #thati am still learning.i try to pay attention to the high-numbered veterans ofRCU.

Last comment: I recommend all of the guys on this forum discussing the ground resonance theory move the discussion to a main post on the beginners forum instead of going uder this guy's blade tracking title. Ifwe start a new postcalled something like "ground resonance" we could probably get a little more outsideadvice from other people searching theforums. Just a thought.

Also heard that Rafael.....you are an engineering major with a math minor......could you give a high school senior some advice in this field. Iam going to Florida State University this fall after I get my instrument rating at my local airport. I am going into engineering (still don't know what kind...I'm leaning toward elecrical??) and want to get a double minor, one in math and one in business. Just want to know how that field looks like. Thanks for the help.

Negative ghost rider...........the pattern is full.

Adios