C/LCombat G
etting F2D planes ready for Speed Limit Combat. I’ve seen quite a few guys try this. It is not as easy as it looks. As usual, the veteran
pilots can make almost anything work. Re- designing the plane on the fly and getting it to fly well does take a bit of time. The first approach is to set up a plain bearing 25 on mounts that fit the F2D ship. Since most of the F2D engines have a closer mounting bolt spacing than the usual 25 LA, 25 FP, or Thunder Tiger 25, new engine mounts are needed. Metal mounts can be cut out of ¼ × ½-inch aluminum strip with a hack saw, file, and drill press. The key is taking care that the mounting bolt holes are nice and square and mounting faces are square on the engine block. An easier alternative is to buy ready made mounts from one of the suppliers on the Combat circuit for $15 or so. For most F2D planes the mounts will need a shim about 0.1 inch thick to mate up the wider crankcase spacing with the small engine block in the plane (usually 1.04–1.1 inches) Thin strips of aluminun, steel, or fiberglass printed circuit board all work well. With a little care you can even sand a strip of 1⁄8- inch ply down and saturate it with epoxy. Using metal mounts can be tricky. For everything to work right the parts have to be square and pulled down evenly. Start by dry fitting the mounts to the engine and lightly tightening the screws. Then fit it, with the shims in place, on the plane. Take a close look to make sure the mounts look like they are flat on the engine block. Light- ly tighten the bolts on the plane. Then take the engine off the mounts and double check that it sets evenly back in place. If all looks good bolt it back in place and gradually
by phil cartier You can reach Phil Cartierat 34 Sweet Arrow Dr, Hummelstown, Pennsylvania 17036, or via e-mail at
philcartier@earthlink.net
PHOTOGRAPHY: PHIL CARTIER
Speed Limit from the 2007 Nats (L to R). Ashley Wilk was the best Sportsman flyer with an old Slow plane. Her dad, Steve, took second with a modified F2D, Phil Cartier was first with a modified F2D, and Pat Zerfoss came in third with another modified F2D with a big stab and heavy spinner nut.
tighten all the screws to pull them down evenly. When the mounting bolts to the plane are good and snug remove the engine again and check that it still easily fits flat on both mounts. It it does you can tighten it down for good. If you simply can’t get everything to seat squarely you’ll have to bed the mounts in epoxy. Glue any shims together with a few drops of CyA glue. Makes ’em easier to han-
dle. Put some epoxy on a 2-inch wide strip of polyethylene cut from something like a Ziploc® bag. Nothing sticks permanently to polyethylene. Bolt the mounts lightly to the engine. Put the plastic sheet in place with the glue down, add the shim, and slide the engine in place. Lightly tighten the mounting screws in
the plane. Then crank down hard on the en- gine mounting bolts and back off on the plane mounting screws and tighten them just enough to squeeze the glue a bit. We’re using the engine to square up the mounts on the plane and the glue to take up any slack. Once the glue hardens the faces of the mount should be square enough to use reli- ably without twisting the case of the engine. Planes come with different types of engine
blocks. Some use blocks cut from ply and saturated with epoxy and glassed. Others use four short mounting bolts screwing into threaded inserts in a wooden block. Some use an aluminum insert all the way through the block, and some use just a plain, epoxy- sealed block of a moderately hard wood like bass or poplar. Be careful with this style mount block. Once the bolts are tightened down evenly it will be okay. But because the wood is fairly soft it can take a set if the plane sits for a day or two. The bolts need to be loosened after every
Dan Reedy, with his OS 32 powered 500+ square inch plane, leads Louis Lopez, with his 440 square inch Hobart Special and modified 25 FP. It’s kind of a shame OS quit making the FP, or at least didn’t keep the same light case when they went to the LA series. Big engines need big planes. The combo can be very competitive, especially on .018 lines.
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flying session and tightened every time you go to the field, or else the pressure from the bolts will keep squeezing the block thinner and you’ll have to start adding shims to keep the engine square. The other types of block either don’t squeeze the wood, or like the ply mounts, they have enough vertical grain that it is as stiff as aluminum and won’t take
JUNE 2012
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