From: "Paul Stowitts" Subject: COZY: Weighing In Date: Sun, 24 Dec 2000 18:48:03 -0800 I had the opportunity to weigh my Cozy this weekend. Needless to say, it did not go as well as expected. I had already leveled and measured the aircraft and everything looked very good. I knew exactly what shims to use to level it when I weighed it. Unfortunately, I underestimated ballast needed and, during our first attempt to roll the plane onto the multipliers, the plane tipped back and clobbered the right lower winglet aft section. Fortunately it just scratched the tips of the prop. The damage was a complete annoyance as I had just thought to myself that I could put the epoxy away for good. That's what I get for thinking. I had borrowed some scales that had "4X multipliers" with them. The idea was to roll the plane onto the multipliers, read the weight and multiply it by four. Each mulitplier has a plate that balances on a bar to keep the load at the correct location. Can you see where this is going? Because of this slippery dust that is all over the place (no idea where it came from), the wheels kept sliding off the balance plate. After many attempts, we finally got the wheels to stay. The next problem seemed to be the scales themselves. They didn't seem very accurate and didn't want to stay calibrated. When my first calculations showed an empty weight of almost 1300 pounds, I knew something was amiss. We made some adjustments and finally got a reasonable empty weight of 1135 pounds. After cursing the stupid accident, I packed up and went home to calculate my CG. As I worked on the numbers, it appeared something else was not right. According to my calculator, my empty CG was at 113.6. From that I determined I could have a maximum of 528 pounds in the front seats and I would need to have a minimum of 59 pounds of ballast to fly solo! I rechecked my figures and they all seemed to be correct. I was going to ask the group what others were getting for an empty CG (Owner's Manual had 110.7 in the example) when it dawned on me that while I had used the multipliers on the mains, I had weighed the front wheel directly on one of the the scales. Since the scale was higher than the multipliers, the plane was higher in the front thereby causing more weight to be registered on the mains. What a dolt! I guess I get to weigh the Cozy again. I am gladly accepting ideas on how to do a better job in weighing my aircraft. And I would appreciate to hear what others have gotten as an empty CG, especially with an 8" prop extension and a 3 blade prop. Thanks. Paul Stowitts Cozy Mark IV N166PT Each time we rolled the plane onto the mul From: "Michael Link" Subject: COZY: Re: Weighing In Date: Mon, 25 Dec 2000 06:41:29 -0600 ----- Original Message ----- From: "Paul Stowitts" To: "Cozy_Builders" Sent: Sunday, December 24, 2000 8:48 PM Subject: COZY: Weighing In > I had the opportunity to weigh my Cozy this weekend. .... The damage was a complete annoyance as I had just thought to > myself that I could put the epoxy away for good. That's what I get for > thinking. >Don't put the epoxy away . You still have to repair the damage from the gear up landing that you will make . Yeah, I know, ......I didn't think that I would either. > What a dolt! I guess I get to weigh the Cozy again. Everyone also usually has this experience early in their canard experience. Consider yourself initiated! > > I am gladly accepting ideas on how to do a better job in weighing my > aircraft. And I would appreciate to hear what others have gotten as an > empty CG, especially with an 8" prop extension and a 3 blade prop. Thanks. > I have a 6" extension and a 2 blade. My C.G. came out +/- .1 of the book value.(I don't remember which way, but with that little a difference, it really does not matter, and is within measurement error tolerances). I borrowed aircraft scales from the FBO where I rent my hangar. I considered wt. & bal. calculations to be a safety of flight item, and I wanted the weighing to be accurate. They let me use their regularily calibrated scales . but I was prepared to pay to have them do the work if necessary. Many EAA chapters own aircraft scales that are available to rent. (By the way, my final weight, with carpeted,vinyl covered interior,was 1134 lbs. Regards, Michael Link Date: Mon, 25 Dec 2000 09:37:35 -0500 From: Carl Denk Subject: Re: COZY: Weighing In As someone else mentioned, I got a local Piper Aerostar repair station to bring over their electronic scales, had bought Lycoming parts, etc. from them at moderately high prices, but the $100 or so extra I spent on parts has paid back numerous times. 3 sharp A&E's for an hour with the scales didn't cost anything. Remember the weighing must be done in a completely close building, even the slightest breeze will cause erroneous readings. Check the phone book yellow pages under scales, many times are able to rent a set for a reasonable price. The aircraft must be level (both ways across the longerons, or other reference points). Crosswise isn't as critical, but fore/aft, just see how much the nose moves up/down from the point where it just balances, to where its an effort to hold it there. The EZ's set fairly high off the gear, and when the nose goes up or down, the C.G. moves fore/aft roughly 1/3 that distance. Note that if your airframe differs more than a little from the plans (weight or geometry wise) this change in C.G. location could cause significant differences in flight characteristics.