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Best fuselage construction??

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Old 07-28-2010, 08:43 PM
  #1
gosk8ing
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Default Best fuselage construction??

Hey guys,

I'm currently designing a scale 0.25/0.32 (electric) Chipmunk. Just wondering what the best fuselage construction is.

There are two I'm looking at.
The first one is new to me. I've seen it being used on Brian Taylor and Don Smith plans. It's box shaped with formers attached to the box to give the curvature.
The second one is pretty common. Formers with stringers attached.
I'm looking at planking my fuselage.

What are the pros and cons of both?

Thanks
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Old 07-28-2010, 09:16 PM
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Default RE: Best fuselage construction??

If you are going to plank the fuselage, I would go with the formers and stringers.
Start with a horizontal crutch and add the formers top and bottom.
Bob
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Old 07-28-2010, 10:05 PM
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Chad Veich
 
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Default RE: Best fuselage construction??

I don't know that there is a "best" method as it really depends on the builder's preferences and the airplane being built. I used to prefer the Taylor method simply because it is very easy to build the internal box and get it accurate and straight. The internal box will then provide a rigid structure upon which to add your formers, stringers, and sheeting without much chance of introducing warps. The drawbacks can include unecessary weight and less internal space for things like radio gear and scale cockpit details. These days I prefer to build using the crutch method in most instances and use jigs to keep everything accurate. Just my .02 cents.
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Old 07-28-2010, 11:20 PM
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BMatthews
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Default RE: Best fuselage construction??

If you're planking anyway then the box inside serves no final purpose and just adds weight. The formers and stringers is a better option since it puts the wood out at the skin where it'll do the most good for structural requirements. But again since you're going to plank it there's no need for the stringers themselves or for that matter even the keels. Although a set of either vertical or horizontal keels similar to that used in Guillows models can act as a nice jig to hold the formers in place while you're adding the first planks to the waist and locking everything down. If you use one pair of keels you don't really need the other.

There's an old rubber scale model trick for building full former models with a single pair of keels. It involves glueing a copy of the plans to a flat section of thin but still stiff for the model size plywood. Then you put saw cuts at the former locations. From there pin or tack glue one of the keels in place to the plans on this "comb". Obviously the one furthest in from the cut openings. Then insert all the formers onto that keel and then ease the second keel in and tack glue it down. Clamp or screw the comg to your bench with the formers hanging over the edge and start planking. For the first plank ensure that the formers are all dead vertical. Once that first plank is on things are all locked down and you don't need to worry. Add planks until the exposed side is done. Then flip the comb over and plank most of the other side leaving a good gap to the comb. Reach in and cut away the tack glue spots and slide the almost finished fuselage off the comb and add the final planks to fill in the last gap.
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Old 07-29-2010, 09:08 AM
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WhiteRook
 
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Default RE: Best fuselage construction??

the brian tailor slab sides method is less work . i think the crutch method is lighter.
some use both, the aft of the plane is crutch type and the middle and frontal engine areas are slab sided.
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Old 08-06-2010, 11:32 AM
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Default RE: Best fuselage construction??

If it were 'me' building I'd use the crutch method for this airplane. It is the lightest. Build top and bottom halves separate then join. No worries (as much) about bananas! Erect plenty of formers then plank- no need for separate stringers since planks will be the 'stringers' for an all sheeted fuse. Use narrow planks. Look up ship modelers planking techniques (I build static scale sailing ship models that have to be 'perfect' on the exterior since this is what shows).
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