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HelicopterAerial Photography and Video › How badly do under heli mounts shake during spool up?
05-01-2004 09:58 PM  13 years agoPost 1
ImRich

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Derry, NH USA

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HI,

Perhaps some of you with the different under heli mounts out there (various brands and self made) can comment on how much the heli and mount shake or oscillate during spool up of the blades.

Most heli's blades are significantly off balance when the heli is spooling up for the first time until the main blades seek their proper lead/lag C/G.

I've tried longer landing gear on a heli in the past and this effect seemed worse than when I had shorter landing gear on.

So I imagine that this effect would be magnified even more with the long legs of an under heli camera mount.

Would you please respond with how much this occurs? Please mention the brand of your camera mount also.

If this does not occur at all, please let me know.

Please no brand bashing, please discuss this in a factual manner

Thanks!

---
Rich

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05-01-2004 10:49 PM  13 years agoPost 2
daggit

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Claremont, MN

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my X-cell gasser will shake on spool up (it's normal) but it doesn't really extend to my camera mount (Airfoil) since it's not directly attached..

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05-02-2004 12:59 AM  13 years agoPost 3
Smithprod

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Oklahoma

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I have an Airfoil mount under a JR gasser and another under a JR electric (Airfoil's). There's always minor shaking when spooling up, but it's never an issue. Are you having problems with it?

Brad

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05-02-2004 03:44 PM  13 years agoPost 4
Polariman

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Annandale, Minnesota

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I've got dual vibration isolation and the camera still shakes on spool up. I first thought everything was going to fly apart. But it is normal for my setup.

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05-02-2004 08:33 PM  13 years agoPost 5
heliraptor

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Colchester, Essex, UK

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Yep

It happens, but once the heads up to speed and the blades find their position its fine.

Lee

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05-03-2004 01:39 AM  13 years agoPost 6
ImRich

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Derry, NH USA

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I've seen some pretty bad shimmying going on. I was worried about shaking apart a camera or a mount.

So a lot of you get this, even with the Airfoils?

Hmm.. maybe some can post a link or two of videos of your shaking that happens on spool up so we can see how bad it is?

Thanks, at least I know I'm not crazy.

---
Rich

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05-03-2004 05:02 PM  13 years agoPost 7
flyboy

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North America

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I have heard of several instances where systems did the funky chicken dance and ended up blowing apart from the spool up/vibrations.

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05-03-2004 05:51 PM  13 years agoPost 8
wwellman

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Marlborough, Ma.

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Heli shake

Hi,

I use a Rotor Craft camera mount with retracts on my x-cell gasser. I have experienced the so called"shakes" when spooling up but more so when spooling and down. I found if you input collective carefully when you shut off the engine it greatly reduced the shakes. Hope this helps

Walter
http://WWW.RPVarialphoto.com

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05-03-2004 08:27 PM  13 years agoPost 9
groundeffect

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Canada

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spool up and shakes!

I have recently took my mount up for the first time ( video and stills coming soon! ), and wondered the same thing about spool up and shakes!

My Airfoil M1 carbon 30 does some shaking on spool up.

It would be interesting to share videos/clips of the shaking on our ships.....

I will try to get one next time I am out ( hopefully tomorrow morning at 6am ).

cheers,
Dean

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05-04-2004 12:38 AM  13 years agoPost 10
ImRich

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Derry, NH USA

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yes.. please post some videos of the funky chicken shakes on spool up!

---
Rich

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05-04-2004 12:56 AM  13 years agoPost 11
daggit

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Claremont, MN

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I found if you input collective carefully when you shut off the engine it greatly reduced the shakes
I'm careful to minimize shakes also, on both spool up and shutdown.

I always spool up enough to straighten the blades, then throttle back for warming up before takeoff. I don't see the too much shake on the shutdown.

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05-04-2004 02:02 AM  13 years agoPost 12
ImRich

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Derry, NH USA

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daggit,

This doesn't make sense to me.

Do you spool up before placing the heli on your camera mount? If so which mount are you using?

There must be a lot of shakes if you are doing this.

Or if you have a different procedure, please video it and show it to us (or video it anyway to show us)

---
Rich

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05-04-2004 02:28 AM  13 years agoPost 13
daggit

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Claremont, MN

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Do you spool up before placing the heli on your camera mount?
No, not really sure what the confusion is.

With a gas motor a preflight warmup on the first flight of the day is regular part of the procedure. I spool up with the camera mount attatched but don't take of until the motor is smooth.

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05-04-2004 09:35 AM  13 years agoPost 14
HeliCamSolutions

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San Antonio, TX

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Here is some video of the startup shakes. The heli is a Z230 gasser with a G26 and a full tank of gas. I say that because the Z230 is like a Mac truck compared to the other lighter gassers. I have never found the "shakes" to be an issue.

Short video 52 sec. (Windows Media 9 player required)

http://www.helicamsolutions.com/Video/HeliStartup.wmv

Jody

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05-05-2004 03:25 AM  13 years agoPost 15
ImRich

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Derry, NH USA

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Hi Jody,

Thanks for the video. But I was thinking of a video with the camera pointing at the heli and camera mount would be more useful.

However from your video, I can see that you do not have much shaking going on.

I fly a G23 gasser.. that audio sure sounds more like a glow powered engine to me. Are you sure that's a G26? I'm surprized at how much is sounds like a glow engine if so.

---
Rich

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05-05-2004 07:17 AM  13 years agoPost 16
FCM

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Surrey, England

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Ground resonance

This is what you are experiencing during spool up/down. Its severity is dependant on quite a few variables which even include what surface you are operating from. It is a well known problem with our full sized cousins and used to be a pretty common occurance on early helicopters. As far as I know it has little or nothing to do with the type of powerplant you are running.

Paul.

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05-05-2004 01:08 PM  13 years agoPost 17
HeliCamSolutions

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San Antonio, TX

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ImRich

The clip you saw was the section I cut out while filming the heli from the ground and air. Here is the short clip of it from the other side. We just flew a couple circuits. The heli is a stock ERGO Z230 with a G26 and stock muffler. Stock wood blades and stock tail blades.

Jody
http://www.helicamsolutions.com/Pro60ht/Pro60ht.wmv

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05-05-2004 05:17 PM  13 years agoPost 18
CKY

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Sunshine Coast, BC, Canada

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I resorted to a much lower profile mount for my camera setup. Original problems were extreme wobble on spoolup especially with earlier flat aluminum landing gear. (use tubing)

My mount now 'stradles' the camera mount gear and gives clearence to the camera without raising the heli too high.

Fairly tight blades straightened as close as possible before spool up will decrease the inevitable shake.

Chris

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05-05-2004 05:54 PM  13 years agoPost 19
HeliCamSolutions

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San Antonio, TX

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Thanks for the compliment John...and Chris, I agree with you about the blade being as straight as possible. I make it habit of straitening the blades before spool up and I use the flybars remaining level as a guide.

Jody

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05-05-2004 09:27 PM  13 years agoPost 20
ImRich

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Derry, NH USA

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Jody,

Wow, that video of yours is too amazing.

I would have guessed that you spooled up your heli first, and then shut it down, and then spooled up again for those videos.

Either I am doing something wrong, or you guys are not showing reality!

Every heli I have gets a little wobble as the blades seek their lead/lag C/G. This is from a .30 size glow machine, to my G231 gasser.

Jody, I still say your G26 sounds more like a glow machine. Call my crazy if you like!

And to the person promoting a turbine, John is on the mark, we are talking about main blade lead/lag here, not engine vibration.

I guess I need to find someone to train me how to setup my heli's. I must have been doing something wrong for last 8 or 9 years. I always let the blade spool up set the lead/lag. Yes, I do try to preset my blades straight by eye first, but nothing is as smooth as after spool up.

I have tried blades too loose and too tight. Even with them loose there is some vibration at spool up, it just doesn't take as long to stabilize. The problem I see with loose blades is they are more prone to boom strike with an imperfect auto landing. After I have learned this lesson, I tend to keep my blades tighter and let them take just a bit longer to find lead/lag c/g.

The usual test is to hold he heli with the blades horizontal (and main shaft horizontal). If the blade bolt is just tight enough to let the blade hold itself horizontal against gravity, most consider this the loosest a blade should be.

The second tighter test is to gently shake the heli and see that the blades will not significantly shift on the bolt while held horizontally. This is significantly tighter than the first test.

Even tighter still should only be done after the blades have been pre-spun up and allowed to seek their naturual lead/lag C/G. But the blades must not be so tight as to not be able to move at all as there is a natural tendancy for the lead/lag to change a little in flight.

How loose are you setting your blades John and Jody?

I find it hard to believe looking at Jody's video that a pre-spin was not done before that video was shot.

---
Rich

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