Airplane Weight

When I read of an aerobatic model with a weight of 40 ounces, for example, is that the weight with the engine, fueled up and ready to launch? Or is stated weights just the airframe?

Michael

That is completed "dry" weight, with engine(s), prop(s), spinner, wheels, tank, etc. but not fueled up yet.

Generally the weight is stated as the total weight of the airplane as it comes to rest after the landing. Thus it includes the engine and accessories necessary for flight including tip weight, but not the weight of the lines on the other end or the weight of the fuel which is consumed. Take-off weight would, of course, be higher with the weight of the fuel on board, but the pattern is such, that the most crucial maneuvers, where weight would make the most difference, are at the end of the pattern when most of the fuel has already been burned off.

Interestingly, many flyers tend to understate the weight of their airplanes much as we all like to understate our own weight on our drivers' license. At the FAI trials all planes are weighed at the appointed hour, and it is rather humorous to watch as the other competitors gather round to see just how much each person has understated the "real" weight of his airplane. Of course, some cheating has been known to go on, too, when people will take out the tip weight, the fuel tank, and one even the insides of his engine to get the official weight down to an "acceptable" level.

>Interestingly, many flyers tend to understate
>the weight of their airplanes
>much as we all like
>to understate our own weight
>on our drivers' license.
>At the FAI trials all
>planes are weighed at the
>appointed hour, and it is
>rather humorous to watch as
>the other competitors gather round
>to see just how much
>each person has understated the
>"real" weight of his airplane.

It's amazing how closely the weights of most of the airplanes compare. The vast majority of team-trials quality models are between 62 and 64, with a few outliers on either side. Most are within a couple of oz of what people were claiming. It was kind of fun; some people seem to really care how much their airplane weighs, no matter how well it flies. I would point out that I told everybody mine weighed 61.5, and it measured 61, which is well within measurement error. But then again, I don't care much.

> Of course, some cheating
>has been known to go
>on, too, when people will
>take out the tip weight,
>the fuel tank, and one
>even the insides of his
>engine to get the official
>weight down to an "acceptable"
>level.
>

That 60 lb pull test at 72 oz and above is a strong motivating factor.

Geez, I was just gonna say "No fuel". But when it comes to scales, don't forget that even certified scales have tolerances. Otherwise, you'd trash can 98% of them or more. If you need to get a reasonably accurate weight on your model, you can sneak it into the lobby of the postoffice in the wee hours. My fishing scales are checked annually by the bass club, and are pretty accurate. Some are not. Catch & Release, Steve