mass balance

[Gil Kinzie]

Josh, I am painting my plane and will soon be done. Have the rudder and stabs done. The ails won't come off as the hinge pins are frozen in place and BFI*  wouldn't budge them.  The question is    how do I mass balance the control surfaces? after carefully removing all the mills of paints and gels down to the glass, and respraying careful even coats, do really I need to?  There was no appearant use of coatings to balance them prior to my stripping them.  If this is too big a question for this forum perhaps you know of a link or?
Thanks,
Gil  15133

* brute force and ignorance

[Korey Curtis]

Hey Dust-Boy,

Off the subject of Mass Balance....
If you look at the vertical stablizier section without the piece your trying to balance, is there any way a person could fit a antenna in a void back there and fish a coax up to the front? I believe getting the cable there isnt a problem, its just where I might be able to safely stash the antenna... Thoughts?

PS
Put a hole in the front panel to fix the airflow cover. My hinge was rusted away. Need to find another hinge tonight.... ideas? Also, I was thinking of making that panel accessable for the future... what did you do? :unsure:

[Gil Kinzie]

well the hinge to your vent  isn't really critical  so I would look at home depot,  they have a million types of hinges,  that's what is in my gear doors.

Now  I get your point, you are wondering about the void between the rudder and vert fin,  I thought you meant inside the vert fin.  You know,  depending on where you put the BNC connector ( there are ribs in the rudder flange) it may fit,  but if it ever worked loose it is very tight in there and the connector or wire might be able to cause a jam of some sort, hey engineer   figure it out, but  yea I get your concept and it might work,  I havent measured but I bet that vertical void is almost 40 inches long.  You would have to run you coax all the way forward and it would need to be tied down  to withstand 6G or more or it will rattle.

Tail feathers done and boy do they sparkle, one wing done(not wet sanded), one the bottom serface is ground and sanded.  I can be ready by end of March  but my fuse won't be done yet.

I won't be hurrying to move the tow hook, John at Eastern says it is a "MF" and not something to tackle when under time constraints.

Dust boy

[Joshy]

The ails are blocked by rivets.
You must first drill the rivets, put some oil in,
( in worst case for days or weeks to loosen the rust )
and then pull out the bolts.

The ails are to be mass balanced.
To prevent them from fluttering.
VERY IMPORTENT!!!
Fluttering can explosive damage your glider.

First mass them, then take some hinges and mass the tracking force.
This has to be in the limits acc. the hand book.
If not either sand it or rebalance with weights.

Best Regards,

Joshy

[Korey Curtis]

Hey Dust Boy,

I found out that a single 1/4 wave mono-pole antenna wont have DC continuity through the antenna but a 1/2 wave dipole antenna will have DC continuity. I'm hoping that there was a change between the A models and the B models, otherwise I will be back to looking at purchashing an antenna. I will know all the answers tonight since my radio will be delivered today.

Thanks for you testing and help my freind!   :rolleyes:

Eyes to the sky,
KCfly

[Gil Kinzie]

As I indicated,  my hinge pins do not come out.  Call it rust or weld or whatever.  I have removed the rivets and these pins are siezed,  all five of them.  My book does not mention mass balancing so i have no info to go from

[Joshy]

I see. Also no information in my book.
I would do following:
Call Schleicher they give you the right masses.
++49 6658 / 8912  
English is spoken when you call this number.
Or try: info@alexander-schleicher.de

How to make it?
It´s a little bit complicated when you can´t remove the ails.
Because you habe to weight them one by one.
Then you must hinge them on 2 hinges, take a spirit level and
plumb them longitudinal and transverse until they are at 0.
In this condition you have to weight at the end rail.
This numerical value you multiplicate with the distance betwenn hinge and end rail.
The torque has to be in a limit and all is good.
It may be they give you only the rest mass.
It´s a little bit diffrend from manufacturer to manufacturer.
Fact is: If you have too much rest mass it becomes more probably to get flattering.

Best Regards,

Joshy

Post edited by: Joshy, at: 2005/03/16 11:09

[Gil Kinzie]

Thanks for the info, I will call them,  I have seen the results of flutter and do not want to play.

[Gil Kinzie]

in retrospect, I only left rustfighter in my pins (rivets out) for about a day,  but none out of five would budge in the slightest.  I may try again to remove,leaving penetrating in there for a longer period.

Is anyone aware of a 15  experiencing flutter in the past?  Did it blow up?
Kamakinzie  13133

[Joshy]

No 15 in the past, but some others.

My next tip to get out the bolts:

The problem is:
The wing works like a spring and sometimes remains of rivets block.
You get not enough force on the bolts.
I hammerd on 2 stations:
On the end of the bolts with a punch.
And in the hole from the rivet also with a puch.

Warm the hinges with a flame but be aware not to burn the gelcoat.
Take ice spray ( to get in technical markets ) and ice the bolts.
Than take a punch and give it to them.
It´s tricky and you have very short time.
But often it works.

Got out some rusty bolts out with this.
But never tried at an aileron a hinge.
For info: I worked 15 years as plane mechanic.

Best Regards,

Joshy

[Gil Kinzie]

Well I really appreciate the info  but I am the type who would be looking at the melting glass around my hinge were I to try that and one is already in paint.
My plan at present is to call AS to see if there is a way with them on, or try the more penetrator and time idea. I am delivering plenty of hit to the pins and do not want to damage an ail or the wing hinges.  And  where can I get metric  mini pop rivits, the standard ones I reinstalled had heads too thick  and shafts too small.

[Joshy]

The rivets you get by Schleicher.
Normally they sent them to you by free.
It´s too expensive to write an invoice for this.
( I was told by Mr. Schulze some years ago... ;-) )

Best Regards,

Joshy