Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

propeller balance?

Matronics Email Lists Forum Index -> Kolb-List

View previous topic :: View next topic

Author Message

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Sat Jul 14, 2007 10:38 am Post subject: propeller balance?

Hi,

    I am trying to get Possum's video camera to the  point that I can use it, but vibration is killing me. Due to the enclosure I  have to hard mount it to the frame up by the nose cone. I have it as solid as I  can and braced as well. Even with the camera stabilization there is noticeable  vibration. John H and John W helped me set my blade angle when they were here,  but I painted the tip to get it ready for its Air worthy inspection. I suspected  that I got a bit more paint on one tip than the other, so I rigged up this set  up to balance it. Spraying paint on what appeared to be the lightest tip until  it balanced out. Every thing was level as well. If my methods are correct then  the vibration (still more there than I would like) is not going to go away.  Blades were rechecked and are still right on for angle. The blades were set in  varying positions and did not move from setting.

 Larry C

 [img]cid:002301c7c645(at)usermj5tjr71vq[/img][img]cid:002401c7c645(at)usermj5tjr71vq[/img]

P7140220.JPG

Description:

Filesize:

72.2 KB

Viewed:

219 Time(s)

P7140221.JPG

Description:

Filesize:

74.73 KB

Viewed:

223 Time(s)

Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Sat Jul 14, 2007 11:48 am Post subject: propeller balance?

I got some good movies from my Kolb, but used a non-solid mounting  method. If I remember right, you have a Firestar? So maybe you can use this? If  not, it was free...

 If you have the hoop skid for underneath the nose cone like the MKIII does,  you can use that, because that is what I used. I hose clamped about a  3' length of aluminum tubing to the nose hoop, kinda close to the fuselage,  extending toward the front beyond the hoop. The hose clamps were twisted  up, but it was still good and solid.

 Then you take another slightly shorter piece of tubing and suspend it  just below the first tube, ahead of the hoop, by hose clamping short lengths of  bungee cord to each tube, so that the second is parallel to the first and just  below it, supported by the bungees. Now you attach whatever you are using for a  camera bracket to the lower tube. The camera is now vibration-free and hanging  just ahead of the hoop. You want the tubes long enough to stabilize the camera  so that it can't wig-wag or twist in the wind. I had to add a bit of nose  up trim, but not bad.

 It looks like the pits but it works. Just don't nose over on  landing...

  

 Richard Pike

 MKIII N420P (420ldPoops)

 [quote]   ---

P7140220.JPG

Description:

Filesize:

72.2 KB

Viewed:

224 Time(s)

P7140221.JPG

Description:

Filesize:

74.73 KB

Viewed:

223 Time(s)

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Sat Jul 14, 2007 12:44 pm Post subject: propeller balance?

Thanks for the tip Mr Pike, but I don't have a hoop. Here is  how I have it mounted on the plane. I think that without having it shock mounted  I am going to get this vibration. Perhaps a three blade would be smoother, but I  guess I will never know.

 Larry

 [img]cid:003901c7c657$82297d40(at)usermj5tjr71vq[/img]

P7140223.JPG

Description:

Filesize:

53.64 KB

Viewed:

242 Time(s)

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sat Jul 14, 2007 3:27 pm Post subject: Re: propeller balance?

I've had very good vibration free video by mounting the camera on a wing strut with 1" thick (before compression) foam rubber separating the mount and the strut. There are countless ways of doing the mounting but making the mount shock absorbing is the key.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

JRatcli256(at)aol.com
Guest

Posted: Sat Jul 14, 2007 5:30 pm Post subject: propeller balance?

Gents,

  

 Is it a requirement to paint the prop tips or just a safe thing to do?

  

 John Ratcliffe



Get a sneak peak of the all-new AOL.com.

  [quote][b]

ElleryWeld(at)aol.com
Guest

Posted: Sun Jul 15, 2007 3:44 am Post subject: propeller balance?

I have another design of a Prop balancer I built that is easy to build and works great I will get a pic of it and post it asap

 

  Ellery N447EB

 

 do not archive

**************************************

 Get a sneak peak of the all-new AOL at http://discover.aol.com/memed/aolcom30tour  [quote][b]

possums(at)bellsouth.net
Guest

Posted: Sun Jul 15, 2007 5:40 pm Post subject: propeller balance?

At 02:36 PM 7/14/2007, you wrote:

  	  Quote: 	
		  Hi,

    I am trying to get Possum's video camera to the point that I can use it, but vibration is killing me. Due to the enclosure I have to hard mount it to the frame up by the nose cone. I have it as solid as I can and braced as well. Even with the camera stabilization there is noticeable vibration. 	


 I always had the same problem when I hard mounted it to the frame.

 You could always duck tape it to your head or I've found - most of the

 vibration goes away when you turn you engine off, albeit for a short while.

     [quote][b]

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Sun Jul 15, 2007 8:25 pm Post subject: propeller balance?

I have tried putting a bit of stiff foam under the  camera, wind has been blowing too hard to make it fun, so I am biding my time  waiting for a bit of calm. I have a Sony High 8 camera, so I had a lot of  batterys that fit the camera. Most of them will last the Sony for as much as  four hours. Man that thing eats batteries like candy. I had hoped that I would  be able to smooth the plane out with balancing the prop. It is balanced but  there is still enough vibration that it over powers the stabilization feature. I  stuck the camera to the side of my headset, and got a great view of the hinge in  the windscreen and the heater tube. I am a bit afraid that the duct tape would  pull out my whiskers when I took it off.  Not only that, I find that I am a  good pilot in that my head any eyes are scanning all over the place and I get a  bit seasick when trying to watch the video.

 Larry 

    [quote][b]

jbhart(at)onlyinternet.ne
Guest

Posted: Mon Jul 16, 2007 3:25 am Post subject: propeller balance?

From: "Larry Cottrell" <lcottrell(at)fmtcblue.com>



...........I had hoped that I would be able to smooth the plane out with 

balancing the prop. It is balanced but there is still enough vibration that 

it over powers the stabilization feature. 

.........



Larry,



What you are seeing is the effect of torsional firing impulse on the air 

frame.  As the propeller moment of inertia increases it becomes more 

difficult to speed or slow the propeller.  The causes the firing impulse to 

be transmitted back to the crank shaft, to the crank case, mounts and 

finally to the air frame.  If you wish to see less vibration, mount a 

lighter lower inertia propeller.



You may be able to fool the camera by changing vibration frequency. Reduce 

engine speed and at some speed the stabilizer should be able to keep up.  

Just hope that it is a sustainable flight engine speed.



Jack B. Hart FF004

Winchester, IN

by0ung(at)brigham.net
Guest

Posted: Mon Jul 16, 2007 1:16 pm Post subject: propeller balance?

I had a friend that was going to build a model helo blade balancer…..   it was to consist of an accelerometer and a processor that would take all the guess work out of balancing the prop….  I found when balancing a helo blade….  You could static balance it like you did in the photo….  But when it was spinning up to speed it still needed some fine tuning…     I used a wrap of electrical tape at the mid blade ( the cg of the blade)   and tried it to see if it was worse or better….  Then adjusted it from there…  either more or less tape on that blade or the other….   I will try and see if my friend built something he could market or sell me and find out how much $$$  

   

   

Boyd   

       [quote][b]

Display posts from previous:

	Matronics Email Lists Forum Index -> Kolb-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum