Do i need a bigger engine on floats?
09-20-2003, 02:28 AM
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Do i need a bigger engine on floats?
I have a Goldberg Eagle 2,and i am building floats to it.
This will be my first plane on floats.
It flies great with a os 46 la,but do i need a bigger engine when i put floats on it?
Thanks
Ketil
This will be my first plane on floats.
It flies great with a os 46 la,but do i need a bigger engine when i put floats on it?
Thanks
Ketil
09-20-2003, 03:08 AM
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RE: Do i need a bigger engine on floats?
Depending on what type of floats, but you can probably fly with the engine you have. You may want to go down 1 in pitch on the propellor to get off quicker. Normally if you are not underpowered float flying with the same engine is OK.
09-20-2003, 10:22 AM
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RE: Do i need a bigger engine on floats?
you should be fine with the engine you have. The Eagle was designed for a 40, so you are already up a notch in the power dept anyways.....
09-20-2003, 04:25 PM
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RE: Do i need a bigger engine on floats?
People who have trouble flying floatplanes with the same power that works for them with wheels have bad float setups. Floats are more streamlined than wheels, and even though they have more frontal area it does not mean they make all that much more drag.
THe step of the float should be under the 40% point of the wing chord, or just behind the balance point. THe floats should be mounted so that with the tops of the floats level, the wings have some positive incidence...3 or 4 degrees at least. Floats should be mounted rigidly....flexible landing gear is for grass runways.
The floats should be at least 75% as long as the length from the propeller drive washer to the rudder hinge. And that should be long enoug so that the floats stick out in fron of the prop by 1/3 of the prop diameter. If your plane's size is such that the 75% rule is halfway between 2 sizes of floats, go for the larger size.
Water Rudders should stick down no farther than 1/2" lower than the transom of the float. You do NOT want the drag of the water rudder while you are trying to take off. Water rudders are only for taxiing, and they should not touch the water after the plane is "on-step"
Plywood floats tend to be heavy. Fiberglass floats tend to cost a lot. Blow-molded plastic floats tend to make high-speed boats out of airplanes. All the above are hollow, and make a good place to store water which, at 62.4 pounds per cubic foot, is contrary to getting airborne. Especially when they are partially filled and a big slug of water sloshes to the rear of the float, carrying the center of gravity aft with it. This makes for a particularly short but spectacular flight, followed by a boat ride to retrieve the pieces.
Foam floats are leakproof, efficient, light, and durable.
THe step of the float should be under the 40% point of the wing chord, or just behind the balance point. THe floats should be mounted so that with the tops of the floats level, the wings have some positive incidence...3 or 4 degrees at least. Floats should be mounted rigidly....flexible landing gear is for grass runways.
The floats should be at least 75% as long as the length from the propeller drive washer to the rudder hinge. And that should be long enoug so that the floats stick out in fron of the prop by 1/3 of the prop diameter. If your plane's size is such that the 75% rule is halfway between 2 sizes of floats, go for the larger size.
Water Rudders should stick down no farther than 1/2" lower than the transom of the float. You do NOT want the drag of the water rudder while you are trying to take off. Water rudders are only for taxiing, and they should not touch the water after the plane is "on-step"
Plywood floats tend to be heavy. Fiberglass floats tend to cost a lot. Blow-molded plastic floats tend to make high-speed boats out of airplanes. All the above are hollow, and make a good place to store water which, at 62.4 pounds per cubic foot, is contrary to getting airborne. Especially when they are partially filled and a big slug of water sloshes to the rear of the float, carrying the center of gravity aft with it. This makes for a particularly short but spectacular flight, followed by a boat ride to retrieve the pieces.
Foam floats are leakproof, efficient, light, and durable.
09-21-2003, 09:19 AM
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RE: Do i need a bigger engine on floats?
Thanks fore the input,this will help me a lot.
after all, it was a little bit more than put the floats under the plane ,which i taught.
I am so looking forward to my first take off on water ,and with yours help i think this will go fine.
Thanks fore the help
Ketil
after all, it was a little bit more than put the floats under the plane ,which i taught.
I am so looking forward to my first take off on water ,and with yours help i think this will go fine.
Thanks fore the help
Ketil
09-21-2003, 07:48 PM
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RE: Do i need a bigger engine on floats?
I added floats to my Great Planes Easy Sport 40. It was underpowered and overweight(lots of epoxy from repairs)with a LA.46. After trying a couple different size Saito's, I finally stayed with the OSFX91 I mounted. This plane is now overpowered and it screams at full throttle! It get's up on step quickly and is airborne immediatly. I'm at a very high altitude (over 6000ft.) so the extra power is nice to have.
