PDA

View Full Version : Aleron balancers finished



Michael Az
10-10-2005, 09:23 PM
A couple weeks ago I was asking about the functioning of these tools as I needed to make a couple. Somebody wanted to know how it went and here are photos of them. I used power hacksaw blades and made them adjustable for extending in and out. Added some fingergroves to help with lifting them, they must weigh 40 lbs apeice. They look better in real life.
Michael
http://myweb.cableone.net/michaelaz/balancer1.jpg
http://myweb.cableone.net/michaelaz/balancer2.jpg

torker
10-10-2005, 10:38 PM
I have no idea what they are for but they look pretty darn good in the pics too.

david_r
10-11-2005, 03:25 AM
Michael,
Are those knife edges for balancing shafts?
Nice job.

Your Old Dog
10-11-2005, 06:19 AM
Michael, thanks for the pics! Looks like some serious aluminum you're working with. Any idea how these are used? I'm having trouble figuring what role the aluminum blocks play in this tooling. Or is it a case of overkill because the aluminum was the customers and that's how he wanted it?

C9
10-11-2005, 09:32 AM
I think what Michael is talking about here is also known as a mass balance.

When an aerodynamic control - aileron, elevator etc. - is deflected a low pressure area is created on the cambered side which attempts to pull the aileron back into alignment with the wing.
Since the aileron has mass and momentum and CG is behind the hinge it tends to overshoot the neutral point and go into flutter.

Flutter is very bad and it doesn't take long until the control surface rips away from the aircraft resulting in loss of control.

The mass balance is connected to the control surface and the weight is forward of the hinge point and damps flutter because the aileron is now balanced with the CG ending up at the hinge.

If you've ever visited a model airplane flying field, U-control or RC, more than likely you've heard a buzzing sound from one of the models.
The buzz indicates flutter and if the pilot doesn't slow the aircraft down it doesn't take long until the fluttering control surface takes leave of the aircraft and the results that follow can be spectacular.

Most times flutter on model aircraft is caused by too big a gap between the control
surface and flight surface - IE: aileron and wing etc.

The gap area on full size aircraft is well sealed in most cases and quite small in the others so it's strictly a CG vs aerodynamic loading problem which the mass balance cures.

A good example of a mass balance is seen on the elevator of a P-38 fighter plane.
The mass balancer is the streamlined teardrop device you see that is above and below the horizontal stabilizer and elevator.
It's located forward of the hinge C/L in the middle and front of the elevator.

[This message has been edited by C9 (edited 10-11-2005).]

[This message has been edited by C9 (edited 10-11-2005).]

Michael Az
10-11-2005, 11:14 AM
Thanks for the compliments and yes David, those are knife edges for the shafts of the ailerons.
YOD, they are all steel, no aluminum. Customer wanted them heavy, some of the ailerons are pretty heavy.
Michael