da Rock
Posts: 6128
Joined: 10/11/2005
From: western,
NC, USA
Status: online
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ORIGINAL: Avaiojet
Da Rock,
Great observations.
Here's why it's difficult to determin weight "before" construction. In construction, with model airplanes, the designer can choose woods and chemicals. No two builders work the same?
The question was what weight. The answer is "strong enough to survive, light enough to want it to survive."
It's actually not hard to make the decisions you mention. Any experienced builder expands his understanding of what wood is needed where and refines as he goes.
I've got a couple of boxes of balsa in my shop. I used to take a Triner scale to the LHSs whenever they got in new shipments of wood. I'd weigh and mark each piece that looked worth buying. Some contest grade is too weak no matter what the weight. Some is too heavy no matter what the strength. One box in the shop has the contest balsa that was outstanding.
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It's the calculated use of these elements that the builder can use to actually keep his weight down. My goal.
One example would be the use of balsa spars VS. hard wood spars, This model should have forward and rear spars. I expect to have D tube construction with one rear spar centered in the rib. Possibly hard wood for this spar but certainly hard balsa.
The design calls for twice as many ribs as needed, just for scale appearence. So, in actuality, I could use soft balsa for half of the ribs and hard balsa for the other half.
If I wanted to take it this far.
Do you?
So what you were really looking for in your original post was a string of answers to all your building choices?
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Each and every area of construction can be dealt with the same way. Built up stab and sheeted VS. solid.
So, with consideration to all these areas, the builder can build a really light model for it's size.
A table could be made from the "results" of other modeling projects. All a modeler has to do is supply the following"
Wingspan, wing area, engine choice and engine weight, and the total weight of the model with the engine in place.
Comparing the results of many models and determining wing loadings, could help me considerably.
Unfortunately, noone has published their notes from all their building jobs. I'm sure my competition stunter notes wouldn't help you much. But if you want to know what designs (foam wing, cored foam wing, foam ribs, D-tube vs I-beam spars, sheet stabs, etc etc) can be built lightly enough for your choice of size and powerplant, all of them can. By a builder who is experienced in the type he chooses. Probably the last category that demanded the very lightest design that had to stand the greatest stress was C/L Precision Aerobatics. Unfortunately, they didn't evolve to your chosen size. But you're just about to mention the perfect answer to your request ->>>>>>
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Dick has a life long histry of building light. His efforts and results has proved this.
His Jungmeister at 17lbs with 1800 SQs. is a fine example. Thing is, will modelers offer this information and will it be accurate?
Charles
It's not exactly your specs, but if you were to use the same construction it'd work. So your next question is probably, "how do I make sure I build it like Dick did?" You don't. But you do what taught Dick what he knows. Build it and see.
Advice on how to wind up as an experienced builder? You're already starting out great. Pick an experienced builder's models to copy. Copy the ones the size you are going to build. If you don't copy the model exactly, then copy the general design. If you've got Dick's old construction articles, what more do you need? If you don't have his articles, use any you have. And try to find any of models that beat Dick's. chuckle...... Not an easy task. But copying other successful model designs is how lots of good modelers found out what to do and how to do it.
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