Sport Cub floatplane

[alaska cub]

I just put BB on 1500 Baumanns'. Exchange weight resulted in a 100# EW increase for a total of 972 on floats. I have flown it just two times and thus any information provided is subject to change as I get more familiar with the plane. With the 50" cartridge in the Sensenich, and the HC pistons and 4 into none exhaust it has a static RPM of 2550 and is nearly at 2650 at lift off. I estimated the shortest takeoff using one notch of flaps, to be around 6 seconds with just me (240#) and full fuel(24 gal). Climb out is very impressive and at 2500 RPMs cruise speed was 108 MPH indicated. This from Lake Hood at 58 degrees no wind and at 1000 msl in cruise. The HC cyls seem to be quite fuel efficient burning right at 5 GPH at altitude at 2500 RPM. This computed after almost 25 hours flying it on wheels from Yakima to Anchorage. Oil consumption is around one in 8 hours and seeming to get even better. Cyls have approx 30 hrs total. I have owned several 150 cubs on floats and can say that this set up would clearly out perform any of them in avery way. It is not even close. Remember the 150 cubs had only a 1750# gross from the factory and on floats most only had around 400 useful. The horsepower to weight ratio with nearly 120 HP is much better than a 150 cub and right in there and maybe slightly better than a 180 cub and the wing loading is far better than either, so it is no surprise that it takes off and climbs better. Of course it will not haul the load that a cub will with gross weight increases and my guess is that at increasing heavier loads that the 180 cubs will surpass it at some point. Having to burn only 5 GPH helps in keeping the weight down as I believe that the 24 useable will take me further than 36 in either a 150 or 180 cub. I am going to put in a 48 cartridge in hopes of getting a little over 2600 static and see how it performs off the water. The floats came with the dorsal fin which with hardware weighed almast 7 #. I did not install it and wondered about fishtailing without it. I did not notice anything. and when I tried flat turns the plane had a tendency to go back to neutral. I think that the stiff float steering springs help in that regard. BB may be one of very few Sport Cubs on straight floats and certainly the only one in Alaska. People are always coming up to me and asking questions and remarking about how nice it appears. Plane is certified XLSA More to come.

[randylervold]

Don't forget your gross weight with floats installed is now 1430. If your "exchange weight" was 100 lbs. then you gained 10 lbs of useful load in the increase from 1320. Very glad you're enjoying your new Sport Cub!!

BTW, please consider installing your ventral fin. We did extensive flight testing with the floats, including spins, and the ventral fin is there for a reason.