RCU Forums - SIG Sun Dancer .50 Bipe

This ARF built beautifully...it was actually enjoyable, the best so far.. I didn't change much except to add the checkerboard and a polished Aluminum spinner. It was a 2-3/4" Hanger 9 Spinner with a Hangar 9 locking nut and spinner screw set.

I took my SIG Sun Dancer 50 Bipe to the field on Saturday and tested it out. It flew okay, but I had a few issues. I had powered it up with a Saito .72 and had used what was recommended as the "Middle" prop, a 12 X 8 Zinger wood. It was dogging around the pattern really hard, and when trimmed the nose was HEAVY...REAL heavy. Inverted I had to pull a LOT to keep it from climbing straight up from level. The motor sounded like it wanted to just poop out. The all-up weight had turned out at just over 7 pounds, about 6-1/2 lbs dry weight. This was as close as any plane had ever turned out to factory specs (listed at 6 pounds on the box), so I thought I was doing well, but it wasn't really happy at that weight, although it did land very nicely. I had added onboard glow to it and that added to that weight and it had its own battery, to make it even worse. The plane performed fine, just had this small laundry list of things to work on. All my planes have them after the first time out, this list was a little longer than most lists I end up with.

Brought it home and the first thing I did was stop by the Hobby Shop and picked up a variety of props to test out. Testing right now shows the Saito .72 really likes the 11 X 7.5 Zinger Wood. I have an 11X 8 in case it turns out to wind out a bit too much at speed in the air. But I think I have it zoned in. Next, I opened it up and tore out both the main and glow battery packs. The main had been a 2700 I’d been working with based on the recommended CG. But since it turned out so nose heavy the first time out I downsized that to an 1100. I tore out the onboard glow and its switch and charger combo, and added a very light and simple remote glow for starting. This Saito .72 seems to be fine without onboard glow, even though it’s inverted. The 1100 mAh battery pack had to be relocated about a third of the way back in the tail to make the new CG work without lead. Since I was trying to keep it light I felt it was worth the surgery. The CG turns out to be a full ¼-inch behind the furthest back recommendation from SIG (where they recommended for full-on aerobatics), but that’s where this Bipe has its center, no doubt about it. So I cut in through the Tail bottom, added a battery tray, and then closed her up and recovered the tail underneath. I’m pleased to say that by the time I was done I had lightened her up nearly a full pound.

I have also taken out the stock tail gear, which performed like ….well, like all the gear that comes with ARFs these days. Sullivan 6-Lb steering gear has been installed on the back, that’s done and it’ll steer perfectly. And I have added an exhaust deflector to keep the plane a tad cleaner, the goo was really piling up on one wheel pant and gear, and some on the wing.

I can’t wait to see how she performs with these upgrades!

~ Jim ~