Crusair on Floats
04-30-2008, 12:27 AM
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Crusair on Floats
Here's my latest seaplane. It is a Crusair, designed about thirty years by the late Woody Woodward. Sort of an old time free flight type of plane. 550 inches wing, three channel. We used to race these with K&B 40's. No mufflers, of course. This one has an Astro 19 brushless. I redesigned it for electric by substituting plywood with light ply and using thinner balsa. The struts are 1/16th by 1 aluminum from OSH.
The floats are from BJ. I won them in a raffle a few years ago and couldn't find a use for them till now. I used the same basic design scaled up a bit for my very successful Falcon 56 floatplane.
When I tried it as a land plane it performed better than I recall the glo-powered version did, probably because of the light wing loading. The plane was actually too light at three pounds to fly in the typically windy afternoons. The large amount of dihedral and high lift wing made for problems as it neared the ground. It would just park itself at the end of the runway during an approach until the wind quit and then plopped down and bent the gear up and knocked the motor off. As a floatplane it is 3 and 1/2 pounds. I'm using a 4 cell A123 battery salvaged from an EBay DeWalt pack. This gives me about 84 watts per pound, which should be enough.
I went to the Lake Casitas float fly a week or so ago and saw only 2 planes that weren't ARF's. Hopefully this weekend I'll be able to try this plane at Castaic if it isn't too windy.
What do you think?
John in Kalifornia
The floats are from BJ. I won them in a raffle a few years ago and couldn't find a use for them till now. I used the same basic design scaled up a bit for my very successful Falcon 56 floatplane.
When I tried it as a land plane it performed better than I recall the glo-powered version did, probably because of the light wing loading. The plane was actually too light at three pounds to fly in the typically windy afternoons. The large amount of dihedral and high lift wing made for problems as it neared the ground. It would just park itself at the end of the runway during an approach until the wind quit and then plopped down and bent the gear up and knocked the motor off. As a floatplane it is 3 and 1/2 pounds. I'm using a 4 cell A123 battery salvaged from an EBay DeWalt pack. This gives me about 84 watts per pound, which should be enough.
I went to the Lake Casitas float fly a week or so ago and saw only 2 planes that weren't ARF's. Hopefully this weekend I'll be able to try this plane at Castaic if it isn't too windy.
What do you think?
John in Kalifornia
04-30-2008, 10:18 PM
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RE: Crusair on Floats
Hi Jim,
I did a float test in the bathtub. The bottom of the prop is 5 1/2 inches from the water. The distance from the top of the floats to the prop is 3 1/2 inches. On the Falcon it's only 2 inches. I think I need to shorten the struts. Witn the floats level the stab is 11 1/2 inches off the water and the wingtips would be close to 17 inches. I think it would tip over in any wind at all.
Since it is so light, has a flat bottom wing and with plenty of power it should leap off the ground. The spray rails should keep most of the water from the prop. Ecalc shows close to 3 pounds of thrust on a 9-4.5 prop, and almost that much with an 8-6 if I need more clearance.
More after the test flights.
John in Kalifornia
I did a float test in the bathtub. The bottom of the prop is 5 1/2 inches from the water. The distance from the top of the floats to the prop is 3 1/2 inches. On the Falcon it's only 2 inches. I think I need to shorten the struts. Witn the floats level the stab is 11 1/2 inches off the water and the wingtips would be close to 17 inches. I think it would tip over in any wind at all.
Since it is so light, has a flat bottom wing and with plenty of power it should leap off the ground. The spray rails should keep most of the water from the prop. Ecalc shows close to 3 pounds of thrust on a 9-4.5 prop, and almost that much with an 8-6 if I need more clearance.
More after the test flights.
John in Kalifornia
