Thread: Build Log F-35 wood kit build.
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Old Oct 06, 2012, 03:03 PM
Ed Waldrep is offline
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The F-35 and F-22 have a lot of flat surfaces or surfaces with simple curves. I scratchbuilt an F-22 ( pics in the thread here http://www.rcgroups.com/forums/showthread.php?t=311420 )and the only place I really had to use strip planking because of the compound curves was on the engine humps in the back and the upper forward fuselage from the leading edge of the wing forward to the nose. Everything else on the fuselage was 3/32 sheet balsa. I had to wet it with water (or ammonia) in a few areas to get it to bend enough but it worked. I've seen some modelers strip plank on flat surfaces or simple curves and it's not totally necessary. It does solve one problem on a simple curve (like a cylinder), and that is it can prevent the "starved horse" look. When you wet balsa with water, it expands. You wet a flat sheet to help get it to bend around bulkheads to make a curved fuselage (think of the front bottom fuselage of an F-18). When it dries it shrinks, and sometimes I forget that between builds and what happens is you get a dip between the bulkheads. Sometimes it's worse than others, it depends on how tight you make the sheeting. It can be sanded away a bit but sometimes the dip is 1/16 of an inch so there's not enough material to work with. Preventing it is a challenge, more bulkheads spaced closely together helps, but that's more parts to cut and more weight. Strip planking prevents this, but you have to worry about getting glue on all of the joints and then filling the gaps and it's a lot of sanding and filling. All for a simple curve like a cylinder. Sheet is easier! Keep in mind, I'm talking about a simple curve. For a compound curve like a lot of jets have in the nose or rear end or the whole fuselage, strip planking is the only way to get a nice, gradual curve. Think of the F-105 like boogie showed, or the F-100, F-86, etc.

The inlet ducting in that oakdale F-35 really needs work, that first or second bulkhead behind the inlet lets the cross sectional area almost double, that makes for drag and reduced performance.

I tried to fly one of these a few years ago for a guy, it had the glow Toki .18 in it, it was way underpowered and the glow fan installation was poorly done, the hatch behind the fan was not sheeted above the fan so there was air hitting a bulkhead, no wonder it only rotated when the runway edge let the main gear go down, it only gained a few feet before it rolled off to the side and damaged the fuselage.

At least Mshay you aren't going the glow route with that fan, waste of time, not enough power! Good luck!

Oh, and how long is your bird and what fan will you use? The normal size is 50 inches I think? So about 62 inches long for yours at 125%. That should be big enough to carry the weight of a 120mm fan setup at around 10 to 11 lbs. The one build you linked to was 50" long and 10 lbs. Damn, that's heavy and the wing loading must have been really high! Not a very forginving bird I bet. I built a 63" long version of my F-22 with a Turbax 120mm class fan and it weighs 10 1/2 lbs and uses 10S 5000 mah and 4500 watts. It's a LOT more fun to fly that one than the tiny 46" long twin MF 480 original!
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Last edited by Ed Waldrep; Oct 06, 2012 at 03:18 PM. Reason: I built the small F-22 7 years ago, forgot how I did some of it!
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