zkvii

zkvii

Well Known Member
Hi,

We are currently trimming / drilling our counter balance weights.

The LHS is slightly light - added a lead shim (about 13 grams) - looks good now.

The RHS is slightly heavy - about 15 grams is the current estimate.

I'm expecting to fly unpainted for a bit, but those who have painted - how much weight did you have to add afterwards? I don't want to drill and then have to add back later if I can avoid it.

Thanks,

Carl
 
zkvii said:
I'm expecting to fly unpainted for a bit, but those who have painted - how much weight did you have to add afterwards? I don't want to drill and then have to add back later if I can avoid it.
Click to expand...
What I've hear is that having those weights bigger is better than having them too light so leaving them a bit heavy now might be good for flutter resistance. Anyone can confirm this?
 
Pirkka said:
What I've hear is that having those weights bigger is better than having them too light so leaving them a bit heavy now might be good for flutter resistance. Anyone can confirm this?
Click to expand...
Having the weights too heavy probably does add extra margin to flutter. But, the current design has more than enough flutter margin, so we don't need to add any more.

If the weights are too heavy, they will tend to pull the counterweight down when you are pulling g. This will push the elevator trailing edge up, tending to increase the amount of g that is pulled. In other words, if the counterweights are too heavy, the amount of stick force required to pull a given g will be lower. If the stick force per g is reduced, the risk of an inadvertent overstress is increased.

The effect on stick force per g is probably acceptable as long as the amount of extra weight in the counterweight is small. Don't get carried away with adding weight to the counterweight though.
 
Not super critical

Leaving them a bit heavy is not a problem. There has been a fair amount of discussion about this if you want to search the archives. As long as you are close, build on! I don't think many make adjustments after paint - I'm not planning to do so.
 
My elevators on my RV7 go to the stops....

My taildragger RV7 elevator weights go to the stops (too heavy)- What's the down sides to this??

Is this a fine tuning issue or something I should correct ASAP??

She flies better everyday, but I don't have a good feeling how important it is too have the elevators balanced with the horizontal stabilizer.

Any feedback?
 
On my 9A

I had them perfectly balance before painting. After painting I had to add about 6 oz to each. Easy to do, I just drilled a hole in the rib and pored lead shot/expoxy mix through the hole.

Kent
 
6oz per side? That is 170 grams per side.... WOW.

Does this include the control system (push tubes etc) during balancing?

Thanks for the info,

Carl
 
zkvii said:
6oz per side? That is 170 grams per side.... WOW.

Does this include the control system (push tubes etc) during balancing?

Thanks for the info,

Carl
Click to expand...

The push tube was not hooked up, as each side was balance independently. I don't think that the push tube would have much effect.
I placed a paper cup on the counter balance and added lead shot until the elevator was balanced. Paint weighs a lot I guess.

Kent
 
You must log in or register to reply here.