Balance

Brent Colvin · #1 03-18-2010, 07:11 AM

I am in the process of painting my 7. Is anybody out there rebalancing their flight controls after painting? Looks like I do not need to, but A&P helping me thought we should. Any ideas? Thanks

RV7Guy · #2 03-18-2010, 07:57 AM

Hi Brent,

Before painting my 7, the counter balances on the elevators were hanging 1/4" down. After painting, that distance was slightly less, maybe 3/16" or less. I did not do anything else.

Definitely check them. If is near where they were, leave them alone.

Guy Prevost · #3 03-18-2010, 07:58 AM

I did re-balance mine. I installed AN3 nutplates behind one of the tooling holes in the balance arms so that I could bolt on weights after painting.

My elevators took a stack of washers on one side and a small square of 1/4" steel on the other. My method probably won't help you much, but it may help those that are still building. I'm really glad I installed those nutplates.

Bavafa · #4 03-18-2010, 09:33 AM

I setup mine to have as much front side heavy to account for the paint. After painting (I used two stage paint) I was about 5.5 ounce trailing edge heavy. I was quit surprised to see how much of a change there was in the balance. To remedy that, I mixed buck shots with epoxy (total of 5.5 ounce) and pure it thru the tooling hole in the elevator where the weight is. It came out balanced perfectly.

Brent Colvin · #5 03-18-2010, 02:43 PM

Thanks for the replys guys. We will rebalance.

Maxrate · #6 03-30-2010, 07:36 PM

Quote:

Originally Posted by Bavafa

I setup mine to have as much front side heavy to account for the paint. After painting (I used two stage paint) I was about 5.5 ounce trailing edge heavy. I was quit surprised to see how much of a change there was in the balance. To remedy that, I mixed buck shots with epoxy (total of 5.5 ounce) and pure it thru the tooling hole in the elevator where the weight is. It came out balanced perfectly.

I recently completed the empenage and decided to prime the whole tail for storage as I live on the coast. After putting the tail together Im concerned about the elevators being to heavy on the trailing edge. After blocking all the sides with foam and epoxy it seems that I may have to resort to the above remedy. Has anyone else run into this situation. It is an awsome feeling to finally have a section of the plane complete!!

Brent Colvin · #7 03-31-2010, 03:32 AM

Looks good Mark. Second that, it does feel good to complete a milestone!

Maxrate · #8 04-02-2010, 03:08 PM

All, I found a thread on the VAF that has some good ideas on how to fix a trailing edge heavy elevator after paint. I don't know what percent of guys end up with this situation but I imagine if you use a 2K urethane primer and a base coat clear coat for top coating it could easily cause a situation where additional material would throw you out of ballance. Here is the URL. http://www.vansairforce.com/communit...hlight=flutter

Thanks Doug for a great forum!!

Brent Colvin · #9 04-13-2010, 02:05 PM

Anybody know how much Van's recomends that your control surfaces can be out of balance? I know Beech and Cessna have + or - listed that you can live with.

Maxrate · #10 04-17-2010, 09:56 AM

Brent,

Great question. The construction manual says that a properly ballanced elevator will remain "in trail". I called and spoke with Ken at Vans the other day about it and he said that like most GA aircraft the surfaces are mass ballanced and that it is not very critical to get it absolutely perfectly in trail. If anything it can remain slightly leading edge heavy rather than trailing edge heavy. Again this is not a jet fighter and not that critical.

I have seen another post where one builder installed plate nuts for #10 screws to the inside of the elevator horn to add weight if the painted surface caused the elevator to ballance trail heavy. I incorporated this into my project, "just in case". I plan on using a base coat clear coat paint which adds several MILS over straight urethane.

Good luck with the project!