Vibration simulator

[Goldenhour]

I am working on a few vibration mitigation systems for video. They are taken from prior art off the internet. That being said.
What kind of household device do you think would be a good vibration simulator.
Yeah, I already thought of that, might work.

If I could get any to work I'll glady share the results. As I said, prior art.

[halcyon32]

Originally Posted by Goldenhour

I am working on a few vibration mitigation systems for video. They are taken from prior art off the internet. That being said.
What kind of household device do you think would be a good vibration simulator.
Yeah, I already thought of that, might work.

If I could get any to work I'll glady share the results. As I said, prior art.

I have used a hammer drill with an off center round weight. Seems to work well. Hell with enough weight you could take down a house.

[s_linste]

I have been thinking about your vibration issues and I remember you saying one of your problems was vibes under cyclic input. I wonder if that is a necessary evil for helicopter rotors in general? I mean, I have a Nikon D3100 completely free of jello for most manouvers on my T-Rex 700E. But, I can induce some jello with a less-than-smooth cyclic input and I see it quite often when I'm just trying to turn the heli around for a pass (stuff that i know will be edited out). One has to wonder, even if we were in a vacuum with no aerodynamic forces, what sort of vibes could we expect from a rotor during a transient state (like a cyclic input). If everything was perfectly balanced and infinitely rigid, the inertial forces of the blades pitching up and down as they move around the disk would likely cancel each other out -- but wouldn't that only be at steady-state and perhaps not in transition from hover to the desired cyclic input position?

[R_Lefebvre]

Originally Posted by Goldenhour

I am working on a few vibration mitigation systems for video. They are taken from prior art off the internet. That being said.
What kind of household device do you think would be a good vibration simulator.
Yeah, I already thought of that, might work.

If I could get any to work I'll glady share the results. As I said, prior art.

I'm not quite sure what you trying to do, but in the past I have used an orbital sander to try and test the vibration tolerance of the Arducopter program.

[paulGT3]

Have you asked your wife?

[vteknical]

Go pro on the showerhead.

[s_linste]

I wanted to revive this one since even though I am not sure if my new jello is an artifact of the cold weather or not -- I am seeing jello on the DSLR's video feed in Live View mode while the heli is in position hold.

I DO remember seeing it in hard cyclic manoeuvres when shooting video (i.e. turnging around quickly to execute another pass -- video would have been edited out) , but now I get it even under hovering load.

As per my last post above, I am wondering about a fundamental question: can the vibes associated with loading up a two-blade rotor really be "balanced out"? I mean isn't there a degree of pulsing that has to exist even if the rotor is in perfect mechanical balance?

After all, the noise of a rotor is a pulsing one and sound is basically a pressure wave. Shouldn't the sound of a rotor imply a necessary vibration at that same frequency, perhaps increasing in amplitude with increasing collective?

[Goldenhour]

You are probably correct. I remember doing some still shots last summer solstice sunrise. I started when it was still dark.
I forgot what the math answer was but....
At a shutter speed of 1/30 sec.(12,800iso) I could see 8 peaks of light(vibration) in the picture where a utility light was on the picture. At 1/1200sec. later that day I saw no vibration.
My set up at the time was 1800rpm head speed. 164/12, scorpion 4025-740 10s

[R_Lefebvre]

I think you're correct to some degree. You will have waves so downwash pressure hitting the boom in the back, and the camera in the front. Now, is the force enough to create a noticeable vibration? That's a tough question.

[yeehaanow]

Originally Posted by s_linste

As per my last post above, I am wondering about a fundamental question: can the vibes associated with loading up a two-blade rotor really be "balanced out"? I mean isn't there a degree of pulsing that has to exist even if the rotor is in perfect mechanical balance?

After all, the noise of a rotor is a pulsing one and sound is basically a pressure wave. Shouldn't the sound of a rotor imply a necessary vibration at that same frequency, perhaps increasing in amplitude with increasing collective?

It seems that way because the pressure waves reach your ears mostly from one blade position, hence the 'beating' sound you hear, but if you listen from a mic placed on the heli, it sounds much more homogenous and smooth. Think of yourself holding a blade out and spinning around. There is no 'start' and 'stop' point. It's just whooosh, through the air, (until you fall down from dizziness )

Most heli parts that are intended for 3D/ sport flying are just not straight, not round, and don't mesh well when you need a smooth running heli for AP.

My problems were almost always having to do with the tail drive. A lot of the pros switched to direct drive tail for this and other reasons. Of course, now, most are flying multirotors because they're comparatively EASY to get smooth video from. I have a 700 SMR as a backup but hope I never have to use it!

EDIT-
To answer the original question, a voice coil actuator, or speaker could playback any frequency or combination of frequencies from about 20 hz to 15k hz. and vibrate the heli, BUT, mostly in one plane. Vibration on a heli can propagate in all three planes and at different frequencies. Pretty much impossible to simulate, IMO.

[Goldenhour]

Originally Posted by yeehaanow

It seems that way because the pressure waves reach your ears mostly from one blade position, hence the 'beating' sound you hear, but if you listen from a mic placed on the heli, it sounds much more homogenous and smooth. Think of yourself holding a blade out and spinning around. There is no 'start' and 'stop' point. It's just whooosh, through the air, (until you fall down from dizziness )

Most heli parts that are intended for 3D/ sport flying are just not straight, not round, and don't mesh well when you need a smooth running heli for AP.

My problems were almost always having to do with the tail drive. A lot of the pros switched to direct drive tail for this and other reasons. Of course, now, most are flying multirotors because they're comparatively EASY to get smooth video from. I have a 700 SMR as a backup but hope I never have to use it!

EDIT-
To answer the original question, a voice coil actuator, or speaker could playback any frequency or combination of frequencies from about 20 hz to 15k hz. and vibrate the heli, BUT, mostly in one plane. Vibration on a heli can propagate in all three planes and at different frequencies. Pretty much impossible to simulate, IMO.

I'll be anteing up here soon on a multirotor. It's the way of the future.

[R_Lefebvre]

Originally Posted by Goldenhour

I'll be anteing up here soon on a multirotor. It's the way of the future.

Yes, and not. It depends on what you want to do.

Multirotors have a lot of advantages. But they still cannot touch a heli's ability to lift a load, fly fast, handle wind, fly for a long time, etc.

I don't know that it will always be that way, but it is right now, and I really can't see any way out of it.

A multirotor that can lift what a 600stretch can lift is very, very expensive, very large and heavy to transport.

But yeah, I have several of each machine. I use the helis for flying, and the MR's for hovering. That's about what it comes down to.