I just re-read this whole thread. Lots of good thoughts here.
One thing nobody has noted yet is that you cannot generalize about this stuff. I've flown stock wing 150 Cubs that were dogs, and others that just sang to me. I've flown the proverbial "piggish" 180 hp cubs and a couple that flew pretty nice.
Second, you cannot legitimately compare weights of O-320s to weights of O-360s unless you specify the specific engine. There are O-360s that are real close to the weight of O-320s, and there are heavy ones. Bear in mind that these cited weights are without accessories, so lightweight accessories really make more difference than any base weights. If your cub has a generator, stock oil cooler, stock starter and a ton of battery back aft, you can take about 45 pounds off the basic weight with the lightweight mods and Odyssey battery. As Crash noted, the biggest issue with the O-360 is propeller weight, and that hangs waaaay out front.
Which brings me to experimental vs certified. Unless you're talking about an experimental airplane, comparisons of engines running super low fuel flows are kind of irrelevant......I'd love to be able to run Electronic ignition, but so far, at least, that doesn't happen.
To me, there are three primary issues to consider: Weight, Gross Weight, and wing mods when talking seaplane cubs.
Frankly, there aren't many cubs that have a low enough empty weight on floats to LEGALLY carry two people and a decent load of fuel with the stock 1760 pound GW. If I were looking for a float cub, the Wip 2000 pound GW kit would be a must. I sold my Super Cub years ago because I wanted to instruct on floats, and about a third to half of the customers couldn't LEGALLY do a checkride in the airplane due to their weight plus the examiners weight.
So, to me, the Wip 2000 pound GW kit is far more important than which engine to choose, on floats.
Empty weight is also critical. While that 2000 pound kit is essential AT TIMES, I'm NOT suggesting that you have to operate at 2000 pounds ALL the time. A LIGHT Cub flies better and performs better, no matter the engine.
And, if I were buying a SC today, if it didn't have a fairly recent ACTUAL weight, I'd have it weighed prior to purchase. Not because of legalities, but to find out what it ACTUALLY weighs, and where the CG is. There are a lot of Cubs flying around out there with "fairy tale" empty weights. Again, I'm not suggesting this for legalities, but rather for you to know what you are actually buying.
Wings: Again, you can't generalize. For eight years, I worked a 160 hp Cub in Kodiak that had the "original" extended wing mod, ie: the wings were extended two bays, with Demer tips (drooped and extend the wing even further) but with stock ailerons and flaps. Flying that Cub in Kodiak, where there's usually a "little" turbulence, you quickly realized that the ailerons were pretty useless. Rudder was a much better roll control than aileron. Frankly, that cub taught me many things, largely the importance of rudder use, but, it wasn't the nicest flying cub I've been in.
A friend bought a newly rebuilt Cub that had the same length wings, but had the flaps extended and the ailerons moved out to the tips, and "Hoerner style" tips. He let me fly it, and holy cats, was that plane a dream to fly, compared to my work plane. Roll was still a little sluggish, but you still had solid control authority.
AND, both these airplanes got off the water much quicker than a stock wing Cub. Wing surface area is an important consideration in a float cub. On wheels, I would definitely stick with a stock wing or a squared off stock length wing, but on floats, those big wings really make a difference in getting on step and off the water.
BUT, extended wings add weight.....see my earlier comment on empty weight. Everything is a compromise.
There is no doubt that MANY O-360 powered airplanes will takeoff shorter and climb better than MANY O-320 powered Cubs. And on floats, that difference is more noticeable than on wheels. Power, weight and wing area are all key components in a seaplane. But weight is more important to me than the difference between a 160 and a 180 powered cub, in many ways, not the least of which is the "feel" and flight characteristics of the plane. Bear in mind that a very tiny percentage of your flight time is takeoff and climb. How often do you REALLY need that extra power? But every minute you're flying that plane the "feel" and flight characteristics are going to be banging you up side the head.
But, my primary point here is that you really cannot legitimately generalize about this stuff if you're shopping for an airplane. You really need to look at EACH particular airplane, its empty weight, whether it has the 2000 pound GW kit, the wing mods, and finally (and lastly in my opinion) the engine.
Oh yeah, and then there are the floats.....simple: if you can run straight floats, get a set of EDO 2000s. The Aerocets are nice, but all that extra $$$$ for a set of those will buy a LOT of gas, and you won't see much better performance, if any. Nothing else is even close.
And, if you REALLY need to operate on Amphibs, buy a nice Cessna 180 or 185.
MTV
