Someone made mention of the Brett Buck/Dirty Dan mods to a Sig Skyray.
Since I have a Skyray with a 20FP, I kind of perked up and took note.
So -- what are the mods? The airframe is complete (it's built bone stock, and miraculously well given the level of mechanical aptitude of the guy who put it together). It's a nice mild trainerish thing as-is, so mostly I'm wondering if it's worth ripping into for more performance, or if I just want to hang on to it in case someone needs training.
So what needs done?
Virtually nothing. The only performance modifications are to remove the rudder offset and replace the single-wheel gear with a two-wheel gear. I also currently have an enlarged elevator (extra 1/2") but that's a pretty dubious improvement.
I later "modified" mine further after it got completely destroyed at a stunt clinic. The wing shattered into confetti after the first hard crash. I rebuilt it with 3/32 balsa at every station (no half ribs), 1/8 x 3/8 balsa spars, and decent wood for the LE and trailing edges. That lost about 6 ounces out of the wing. It didn't significantly improve the performance but it has proven MUCH more durable than the stock arrangement. All the spruce and plywood did was make it so heavy that the wings just evaporated when it hit. The current airplane has crashed straight in (on grass/dirt) at least 20 times with no consequential damage to the airframe. But even dropping the all-up weight by 20% made nearly no difference in the performance.
But the key to the whole thing is the engine. I did a lot of experiments using small (15-25 sized) engines as replacements for the Fox 35 and similar, uh, "vintage" style motors. The intent was to get at least equal performance but far better likelihood of success with an inexpensive and easily available engine that ran better on a profile. That worked out great - essentially any of the engines I tried provided equal performance to a Fox (even the 15FP) and most of them were tremendously better. The best of the bunch be far was the 20FP ABC, BONE STOCK out the box with the STOCK muffler, as in no modifications AT ALL, as described at extraordinary length in about 100 SSW posts. With a Fox it "flew like a trainer" and was a challenge, at times, to get through a respectable stunt pattern. With any of the alternates, spinning a variety of 3-4" pitch props just like the big boys, it became a pretty competitive system that could win any Advanced contest in the world. I won't belabor it, go to either the Stunthangar or SSW search box and type in "Brett Skyray 20FP" and you will get far more than you ever wanted to know about it.
The key to running other similar engines it to follow the same process I did, largely as described in the SuperTigre G34 thread in the engine section.
If you are going to use a, uh, "vintage" motor, don't spend any time with modifications, it's not going to fly particularly well no matter what you do.
Brett
Topic: Sig Skyray Mods? (Read 6561 times)