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Has anyone weighed their counterweignts after balancing? It would seem that this should be a known weight that would not vary builder to builder if the flaparon was built per plan. There may be a difference on the inboard and outboard flaparons. Your input appreciated.
Interesting question David. I was not aware anyone was balancing flight control surfaces on any Zenith aircraft.
Sorry I didn't specify. I am building a Zenith 750 Cruzer.
Well, there are options such as paint or wrap that might require an ounce or two of adjustment. Or perhaps someone used larger rivets than they had to use. Just tossin' out ideas here...
Carl is correct. Everyone will build a little differently. Most of the difference will be the weight of the covering; I.e., how many coats of paint, how thick the paint coats are, or the thickness of any vinyl wrap.
Commercial aircraft have these factors down to a science but, of course, a home-built has much wider variances of finished weight. Best to just hang it on a fulcrum and do it from scratch.
So the Cruzer drawings or build instructions call out flight control surface balance criteria? There are none for the 701.
I read somewhere that the counter-weights are called for on the Cruzer because it is a Single Strut Wing and has different requirements for flutter control/testing. I think the regulations give the designer/manufacturer/builder the option of conducting high-speed dive testing to prove flutter does not occur or you can balance the control surfaces. Balancing is probably the safer and more consistent method when dealing with the variables of home-built aircraft.
I copied someone's idea from this forum where you cut a section out of the middle of the counter weight, drill and tap as needed to add a screw to hold things in place, and replace cut out section with fender washers, as needed. Balanced the flaperons and painted the weights bright orange in the vain hope that I would not hit my head on them if I could see them. They look very good and can easily be adjusted as paint or vinyl is added to the flaperons. I had a local metal fab shop do the cutting and tapping of mine. Somewhere on this forum someone posted pictures of the process and explained sizes of washers and screws needed to make it all work. Much, much better idea than grinding the weights down.
it sounds like a very 'tight' solution which allows for future adjustments if details are changed or added later. i briefly searched for past posts... i would love a photo or link. thanks for this info. geo.
Search in 750 Cruzer Forum. Use "counter weight" as search term. Lyndon has a written description and photos. I found using washers made balancing flaperons very simple. If you use this method, make certain that the section you cutout is beyond the rounded nose area. It is fun to read and look at pictures of the creative and impressive methods folks have used to improve the looks of the counter weights.
Hi Dave, first of all it is essential that you add the counterweights to your Cruzer so that the flaperons are balanced on their attachment points. I bought and built and now fly a 2015 edition I Cruzer. In my kit the counterweights were grossly overweight so I took them to a local machinist and had them bored out so that I obtained a drilled hole 3” deep and 2.5 inches in diameter (most of the metal!). In my case the resulting hole required no lead shot and I simply filled in the holes with 5 minute epoxy after devising a cone on top of the bored hole so that the cured epoxy actually is higher than the original tip. After the epoxy cured I simply sanded the front of the weight to reestablish the rounded shape. These are safety crucial counterweights because your Cruzer will definitely cruise above the 100mph range, thus the FAA recommends that the elevator and flaperons be balanced to prevent inflight control surface flutter which can kill you. Love flying my Cruzer (I am at 30 hours in phase 1 flight) and have no issues with the control surfaces. Furthermore instead of placing the bungee cord on one of the elevator cables from the side which others have reported causes too much side pressure on the stick, I attached the bungee directly below the cable thus eliminating that issue. I also covered the empennage portion of that cable with polypropylene brake line tubing so that any cable to cable rubbing grinds on this relatively hard plastic. This has proven to work quite well in my Cruzer and I don’t have to fight any stick deflection (the plane flies hands off this was). Hope this helps but you MUST mount the counterweights and they MUST be drilled or bored out so that you achieve a balanced flaperon. Sincerely, John Minatelli