UltraCruiser Plus Engine Mounts
For reasons known only to Hummel Aviation, the UltraCruiser Plus plans, while pretty good
in most respects, don't have enough information on the engine mounts to enable you to build them. And the
UC+ uses a different type of mount than most VW powered homebuilts.
This mount is shown in the Hummel 1/2 VW plans. I bought a set and scanned this detail.
Clever, to a point. What really appealed to this design in general, and this form of engine mount in particular,
is that it's easily adaptable to mounting the prop on the clutch end of the crankshaft, the way I feel it should be. But I
started wondering. Things like, what's the epoxy there for?
The consensus, as I read it, is that the epoxy doesn't do much, if anything, and the thing to do is rely on metal to metal contact to
locate the angles and the case relative to one another, I.E. either taper pins or bolts in accurately reamed holes, use Loctite liberally, and a bit of
high temperature silicon if you must to keep the oil in the case.
I have a junk case I use for this sort of trial vivisection. Let's see how it goes. Here is a raw case. Note that the sump is 9 inches
long, as opposed to 6 inches for the cut case 1/2 VW arrangement shown previously.
Not very flat, ehhh? We'll fix that. My tool of choice is a Vixon file.
In my posts, I'd talked about using AN386-2 taper pins to make this connection. But look at the view below. At least on one side, the oil
pickup will prevent running the needed tapered reamer into the side of the case from the inside. It will also make it hard to spot-face the bearing
surface of the bolt heads. I'll enquire with the gurus if there is a reasonably easy way of getting this thing out, and back in again. Notice also there
are 4 "pockets" in the side of the sump. This infers 4 bolts can and probably should be used to secure the angles vice 3 on the 1/2 VW rig.
