Engine thoughts

I haven’t made any decisions about what engine I’ll hang on the front of this thing when I get to that point. In a conversation with Dave Hertner, former owner of Fisher, I recall him saying that the engine weight needed to be at or below 200# — which would limit my choices somewhat. Small Continentals (A65 through C85 or O-200) are obvious choices, though the smaller ones are a bit less power than I’d like and the bigger ones are rather expensive. Of course there’s always a Rotax 912 ULS, or a Verner or Rotec 7-cylinder radial, or Aero Momentum, and so on. Corvair? Maybe, maybe not; I have yet to see a straight answer to the simple question of, “What does a complete Corvair engine weigh?”

While I have flown a lot behind a Rotax and like it, I’m not wild about the idea of building all of that into the plane, and I’d like something that “sounds better” – or more appropriate for a classic looking biplane. The Rotax sounds great on an RV-12, but it’s just not the experience I want for the Celebrity. Ditto Aero Momentum: I like their engines, but don’t really want to use one for this project.

A few days ago I was exchanging messages with a guy on POA. He’s about my size, and flies a Celebrity — with a Lycoming O-235 up front. He says the weight & balance work out fine, and he’s still got 200# of load – though he didn’t specify the conditions there, so maybe it’s full fuel, maybe just him and no fuel, I dunno. I’ve asked what his plane’s empty weight is.

So, I’m adding the O-235 and O-290 to my list of engines to watch for. The O-235 seems to be pretty well supported for parts; the O-290 less so – seems like new cylinders are not available — but they’re available pretty cheaply and weigh about the same as the O-235. And of course either one could be switched to electronic ignition, vacuum pump deleted, lightweight starter, and so on.

Reflections on fuel tanks

I’ve been thinking about fuel tanks for a while now. The Celebrity normally has a 12-13 gallon fuselage tank, located just forward of the front cockpit Cub-style. In fact it may use a Cub tank for all I know, or a Champ tank. It’s enough fuel for flights as long as I suspect I’ll ever really want to make in the plane, but I’m interested in adding some capacity. I can envision a scenario where I fly somewhere and want to fly home without refueling, or fuel simply isn’t available where I land. Dirt strips, busted fuel pumps, whatever. A couple of wing tanks for some extra fuel capacity would be a welcome addition and give me some added flexibility.

Since the sale of Fisher to CKD.aero, I doubt very much I’ll be buying the tank or tanks from them. I got a price for wing tanks — over $400 each. Nah. They’re simple welded aluminum box tanks, which are mounted in the wings by means of some stainless steel straps attached to the main and rear spar caps.

Welding aluminum isn’t really in the cards for me, I don’t think. I considered building the tanks out of sheet AL, riveted and sealed with tank sealant. I have experience building those for the RV-7 and RV-12, but of course I’d need to design and build these from scratch. That option is not off the table yet.

Lately I’ve been thinking more along the lines of fiberglass. I could mock up the tank using cardboard and then foam board, to get the exact size and shape and work out the mounting attachment details as well as the location and details of the fill, drain, and sump. There are several construction methods possible including making a mold, building it over a Styrofoam plug and dissolving the foam once cured, or building a foam or balsa structure and glassing over the inside and outside for a sandwich construction. I could make it all internal or could make the top surface match the top of the wing, include a flange to attach it to the ribs, and either just paint it or cover with fabric.

Once I get back to work on the wings I’ll do some more exploring. Right now Stu’s got some stuff going on in the shop so the wings are still on the rack. Once he’s ready for me to get back to work, I want to accelerate the pace of construction so this thing is done before I die.