ORIGINAL: cmoulder
ORIGINAL: Gungadin
I was hoping to run my SAP 180 this week end, but we got hit with 6 more inches of snow with a couple more inches due Saturday, so I can only look at my engine. But I hope to get started on my Focus II this week end. About the fuel draw problem, was it only when you were starting the engine ? And what was the cure ?
Thanks, Dan
Dan, glad to hear your Focus assembly can get underway, even if the engine running will be delayed a bit. Oh boy, doncha just wanna crank up that little jewel??!! We also got about 1.5 feet of new snow... sloppy, wet stuff. At least crappy weather encourages us to stay indoors and build.
Speaking of which, my best advice on the Focus II is to place the fuse on a very flat work surface and insert the wing tube, then cross your fingers that the fuse is fairly straight and that the wing tube socket is square with the fuse. I had no such luck with either the Focus Sport or the Focus II, but along the way I figured out a sequence of assembly to ensure that at least the fin, stab and wings come out square/perpendicular to each other, and a quick fix for a crooked wing tube socket. If you are super-anal about having a straight fuse, you'll need a combination Medieval rack/Japanese steam bath to straighten that puppy. I decided just to cheat a little.
Maybe everything will be straight and this will all be moot.
I don't want to stray too far because this isn't a Focus II thread, so if you wish, PM me after you've laid out the pieces and figured out what the heck you're up against. But when actual work begins, you want to do the engine mount and pipe tunnel first. And then the STAB. More on that later.
Just keep thinking all the while, there is a damn nice flying model at the end of the process, and it's okay to cuss while you work.[sm=what_smile.gif]
Nothing wrong with a little building advice. FWIW- I always set the stab to fin relationship first....it's as important a relationship as building flat surfaces. This needs to be as square as possible...even a slight misalignment of a couple degrees will affect flight precision. A simple way to do this is to make a large isosceles right triangle template from 1/16" lexan sheet. Scribe cross-hair from the right angle to the hypotenuse and also scribe a series of parallel lines to the hypotenuse. Make the cross hair as accurate as possible, not to belabor the obvious. Anhedral stab? No problem with the template
Then carefully drill 1/32" holes on the lines such that the template may be pinned onto the fin. The stab needs to align with the hypotenuse parallel lines. I prefer the template because things are held in place while the glue dries. Also, the template should be large enough to serve to prop up the fuse on the work bench while the glue dries. Always a good idea to check fin and stab CL's with a cross laser, making final adjustments as necessary.
The wing socket in the fuse often has to be adjusted to square everything. One should never assume that the factory placements were correct. My current design on the building board started out as a Brio fuse. Once the stab was set, the wing socket in the fuse had to be adjusted 3/32" to get the stab and wing parallel. Unfortunately, factory installation of wing adjsters and all the holes cut for servo wires and such all had to be filled and redone.
I've had to do these adjstments on all composite fuses I've build so far from, cheap to expensive, from Piedomont models to ZN Line.
Matt