When selecting a model to fly, does the weight that is listed, the dry weight or the flying weight?

The weight that is listed on the box is generally a ready-to-fly weight, less fuel (for glow-powered planes). But they usually are quite optimistic. For example, if a trainer plane says recommended engine is .25 to .40 and should weigh 5 pounds, the plane would maybe weigh 5 pounds if you put a very lightweight .25 engine on it. But if you put the larger .40 engine on it it will weigh more.

I think the weights are just a number someone pulled out of their tailpipe.

I just finished assembly of a Great Planes Big Stik 60 ARF. Advertised weight is 6.5 pounds. My plane weighs 7.5 pounds.

Engine OS 91 Surpass II. Weighs 24.2 compared to 23.6 for a 61FX (OS specs from manual, with muffler)
Converted to tail dragger. Added plywood gear mounting plate and tri-stock, no idea what it weighs. Substiututed tail gear for nose gear, probably saved weight there.
Tru-Turn spinner versus nylon spinner.
4 Hitec HS425BB Servos
1 Hitec HS322 Servo
4 AA cell 1650mah nimh battery pack
Hitec Supreme receiver

I have no idea where it gained the pound.

At the factory is a good bet.

If you choose any engine in the suggested range it's going to weigh about what any other brand of engine weighs. And all the radio/servo stuff isn't going to deviate much by brand. So all the stuff you have brand options on will wind up within the same total ounces and the ARF designers really ought to have that figure in their advertised weight. What's left?

What the factory used that's underneath all that pretty covering.

One ~600 sq-in wing for an ARF I built a couple months back weighed almost 2 lbs with two servo's in it.
One ~600 sq-in wing for a different ARF I just built weighs just over a pound with two servo's in it. Amazing. This lighter wing is for a CAP that I throw around pretty hard. It's strong as ......

The two wings came out of different factories.

There have been a few models that actually do list flying weight but who's to know. The A/C that I am looking at states the weight is 11.5 lbs. I have a YS 1.20 DF that I am thinking of trying but of course the engine range states 1.10 and up. What is one to do? I could put a 1.80 Moki but that is already spoken for on another aircraft that I have which I am repairing. If I use the 1.80 Moki I'm not sure that 1.20 will fly the other aircraft as well as the 1.80 did. All I can do is slap it on and try I guess.

I do appreciate all the help and information.

Pull out your Tower catalog and look up some models that are the weight of yours and that are a similar type. Look at their suggested engine sizes. Eleven pound models seem to mostly have 1.10-1.40 size 2cycle engines recommended for them or 1.20-1.60 4cycles. So your 1.20 engine sounds about right. As for the Moki....

Weigh it and compare the weight to what is listed for the 1.20-1.80 4cycles that're for sale in catalogs that list weights. Reverse engineering is no real problem. I only looked at one or two models in my Tower catalog so you might check it out a bit more thoroughly.

What is your model? That information alone would get you a lot better answers to your problem.

The weight on the box is the lightest weight anyone has ever built the airplane minus a little bit.

Bill

The kits that I have built generally list a weight range. For example, 6 1/2 lbs to 7 1/2 lbs. My goal is generaly to build the model lighter than the bottom number. Sometimes I can. Generally my models land on the bottom number.
I have never seen or built a kit that couldn't be built as light as the specified weight on the box. But then again, I haven't built many new kits. Most of my kits are designs that are 20 or 30 years old.
So, perhaps this is a relatively new trend by kit manufacturers to list optomistic finished weights. I have purchased some modern ARF models that advvertised a flying weight of 4 1/2 lbs, a fantastic number for a 40 size aerobat. When I got the ARF, the box actually listed 5 1/2 lbs. That was a disappointment.