AutoMike

Hey fellas, I'm starting the bipe project this weekend. A good friend of mine and I are both building one each from the original Ace kits. We are going to use gas engines instead of glow four strokes, I'll be using a Ryobi 31cc converted with Wacker Engine parts and with CH ignition to keep the weight very close to a glow four stroke. My friend is using a U.S. 25cc stock, but since I hate to add lead to any airplane, I cautioned him that the engines weight might require him to consider a few mods such as moving servos to the tail, moving the firewall back up to 2" or adding a modest amount of lead to the tail and there by increasing the wing loading even more over what his aprox. 4lb engine will add. He seems to think I'm full of it because his kit is a few years newer than mine and the engine recommendation shown on his kit states a range from a 1.20 glow FS up to a G-38 and maybe a G-45. His box has some damage to the label and another engine is listed beyond the G-38 but can't be made out. His way of thinking is that "Doc" is making this statement so no consideration should be given to making any large mods to the airframe so long as an engine within the recommended range is used. Well, he makes a good point in general I tell him, its hard to believe that a 2lb 1.20 FS can be replaced with a 4lb+ gasser and a 1500mah ni-cad flight battery alone can be moved reasonably far enough to provide a correct CG.

I've built a number of Doc's planes over the past 20-25 years and they have always turned out wonderfully when built as he originally intended and I've told my friend that anything more that the 120 is over what his design goal was originally and we are on our own with regard to heavy gas engine installs and any mods to make it work. I've read as many post about the 4-120 as I could find, which wasn't all that many, and only one or two made mention that the plane came out tail heavy, but they didn't qualify that by listing what engine they used or if they used a heavy construction method such as using epoxy perhaps in the tail or an aftermarket tailwheel assembly that might be much heavier that the simple stock unit.

I'm hoping that some of you might offer some incite on your personal experience with this kit or if any of you might have an old mag with the original construction article, circa 1986, or a kit review and might be willing to part with it or make a copy of it for a fair price plus shipping.

Thanks for any help. Mike E.