Corvair power?

[rampilot]

New to the group. Just got back from OSH with a head full of ideas. Eager to get the OK for the CEO (wife) to begin in earnest... I think having her try on the trike - in the left seat! - at the Kitfox booth may have sealed the deal! She liked it waaay better than her C150.

Most anyone here knows more about Kifoxes than I, so... Does anyone have any ideas/thoughts/experiences/wisdom regarding a Corvair conversion on a Super Sport? Too heavy?


Any insight is appreciated,
ram

[RandyL]

I suspect a Corvair would be too heavy. Also, the firewall forward kit from Kitfox is configured with everything you need for a Rotax. If you use another engine you'll need to engineer many of the systems yourself. Imagine having to design and build your own cowl for example.

General rule of thumb for any customizations you make when building a kit aircraft: multiply the time required for that area by 10x. That said, they are "experimental" aircraft and we all get to pursue the path we prefer.

[rampilot]

Randy - Good point. So it got me to wondering if one could use the KF supplied cowl and modify the baffle, but - if my mm to inches conversion is correct - the Corvair may also be too wide at ~28 inches. Keep researchin'...

Another question - you ordered the QB wing. The KF web site isn't too clear as to what's included over a standard wing?

BTW - Good job on the mykitfox.com site!

ram

[RandyL]

You raise another issue... baffling. the Rotax FWF kit doesn't have any baffling since it has water cooled heads. With a Corvair, or any other air cooled engine, you'd need to come up with baffling to control the cooling airflow. That's a whole black art unto itself!

On the QB wing, it comes with the skeleton fully assembled, all other tasks still need to be done by the builder. Still, there's lots of ribs that would normally need to be glued in place. Perhaps others can comment on how much time it saves.

[Mark]

Hi Ram,

If there was only one QB item to purchase from all options available, I would recommend the QB Wing. Imagine building a wing to tolerance on sawhorses vs. someone who has built hundreds of them on a factory jig. The amount of time and headaches saved is well worth the reasonable price.

You will install your tanks, lift strut brackets, and some other associated hardware which is pretty straightforward.

[crazyivan]

ram, I like the idea of hanging a Corvair on the front of the SS. I've been thinking about it for a while and believe it would be a good combination.

Caveat...most of my opinions about the Corvair engine in an airplane come from William Wynne at www.flycorvair.com. I have spent a lot of time thinking about risk management regarding the Corvair and have some academic opinions but no real experience, except for that '66 Monza I owned several years back. This is the way I see the installation:

It is lighter than a Lycoming O-235 or O-200 and about 40 lbs heavier than a Rotax 912S. But since the SS can go up to 1550 gross then this is not a problem. It will actually help the cg if you intend on hauling a lot of stuff in the cargo area. If you want to go for an LSA certification then you might want to look at the rotax or Jabiru.

It is less than half the cost of a Rotax installation.

William Wynne has engineered a lot of parts to do the coversion. It is not a plug-and-play installation like the Rotax, but it is not starting from scratch either. Things you need to engineer are cooling baffling (which I think you would be able to use the stock cowl), exhaust, intake manifold, mount, and some of the fuel lines. The good thing is that WW has the beginnings of these systems for sale.

As for the risks involved, the Corvair has suffered several crankshaft breaks in-flight. Simply put, the front crank bearing is not big enough and the crank is not strong enough to absorb the gyroscopic and torsional loads of aerobatic flight, a heavy prop, or a high-horsepower motor. Right now I believe the only proper way to operate a Corvair on a plane is with a light prop, no aerobatics, and limited to 100hp.

I want to build my Corvair engine with the big bore (3100cc) and get about 125 hp. There are a few options that I need to explore. First, I am waiting for the results of WW's "fifth bearing" design which adds a larger bearing surface. Second, there are a few people that make billett crankshafts, but these might cost-prohibitive.

My only other reservation is the future of gasoline. If the ignorance of our legislature continues to mandate higher blends of crap-ethanol gasoline then it will not be a viable fuel for aircraft. Will a whole new line of engines that run on flex fuel or heavy fuel (diesel/Jet-A) be available in the future.

How about a big rubberband? It's easy, cheap, and no problems with ethanol.

[tleed]

Looks like I'm going to be something of a pioneer here. I'm planning to hang a Corvair on the front of my Model IV-1200. I did a lot of talking and reading before I went with that combination.

I've been to one of William Wynne's "Corvair Colleges". The info stream there was way too deep to drink all at once. Suffice it to say there is a large support system there. I wound up opting for one of the fifth bearing set-ups with a nitrided crank. I'm not a daredevil.

As to weight, apparently Subie's are pretty heavy and there are a significant number of them that have been hung on the front of a Model IV.

William Wynne has also done a lot in regard to cowling, baffling, engine mounts, intake/exhaust, etc. In fact, I'm carting my frame down to SC in a couple of weeks to have him help me work out the engine mount and an upcoming Corvair College.

Thomas

[Dead Roman]

William has posted on his site thet he feels the model IV and up would be more than satisfactory for corvair use. I plan to build his 3100cc motor rated at 120hp. Its also the lightest model. Throw in the fact that im gonna build it up as hand prop only any you drop even more weight.

[Slyfox]

hand prop, why on earth would you want to go threw that garbage for?

[Dead Roman]

Whats wrong with hand prop? People been doing it for years.