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View Full Version : Shakes while weighted down

Tag1260
09-23-2008, 10:20 AM
I have been setting up my heli (HDX450 ) and it wants to vibrate while weighted down for testing. Is this a problem or is it a common occurrence when weighted down? I have a bar over the skids and two weights on either side to keep it from lifting off.

Thanks
JEEPWORLD2002
09-23-2008, 10:35 AM
never a good idea to do what u are doing :( just hover the heli to check for blade tracking. And yes 2 answer ur ? yes making a heli act as a fan will make it viberate.
Pinecone
09-24-2008, 08:46 AM
It is called ground resonance and it can DESTROY your heli.
sd0
09-25-2008, 09:12 AM
It is called ground resonance and it can DESTROY your heli.


Here is a cool video to prove it:

-LFLV47VAbI
Geese Howard
09-25-2008, 01:31 PM
Why would they keep it running if it was shaking that bad.... :dontknow
Skiddz
09-25-2008, 01:47 PM
That was done for demonstration purposes..
Geese Howard
09-25-2008, 02:00 PM
I wish I had that much money that I can destroy a helicopter just to be like "Yeah, don't do that."
jaywhy
09-25-2008, 02:04 PM
I'm guessing if you live in the states you helped pay for that one! :)

Wow, I hadn't seen the back view of that `test` - freakin' awesome. Reminds me there is a new show starting called something like `Destroyed in Seconds`. Nothing but stuff getting destroyed.
Leaf Blower
09-28-2008, 12:35 AM
I'm sure that they waste much more money that that! I'm sure that they squander that amount of money in the same time that it takes to write this sentence. And of course- they don't stop there - they will keep going and going and going .....
Pinecone
09-28-2008, 08:52 AM
Well, they can do a test like this. And vidoe and gather lots of good data about exactly what happens. Or they can wait until it happens in real life, and have no video, and kill a few crew members at the same time.

Makes sense to me.
Tag1260
09-28-2008, 10:27 AM
Thanks for the info. I guess I won't be doing that anymore!!! LOL
Thanks again
Tag
Dr. Memory
10-01-2008, 03:58 PM
Here is a cool video to prove it:

-LFLV47VAbI

For us RC hobbyists, this one's even better:

fln6I2bhk6I

That was the poor schlub's first flight with the heli. I know how he feels, although my first flight crash was due to pilot idiocy, not ground resonance.
Tag1260
10-01-2008, 04:16 PM
Would coming off the throttle have saved it?
driftless
10-01-2008, 05:02 PM
OK...I was under the impression that it only occurs on 3-bladed+ designs and has to have a fully or semi-articulated design.

I understand the lead-lag hinge problem in these designs.

With our RC helis having the mount point like a lead lag hinge will it still affect us?

I have yet to hear about a 2-bladed heli having ground resonance problems.