Pontoons
05-25-2011, 06:43 AM
#1
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Pontoons
I would like to find out some info on pontoons. I recently aquired a set of pontoons and I have a alfa 40 trainer that has been grounded for about a year and I thought what better way for me to use it. My question is how far forward should the pontoons sit in front of the prop and/or where is center of gravity?
I have an os 40 on it what will I need to get it out of the water?
now for the tricky question, since I have knowone to walk me threw this what is the best way to control it fo a sucessful flight?
thanks for the help.
I have an os 40 on it what will I need to get it out of the water?
now for the tricky question, since I have knowone to walk me threw this what is the best way to control it fo a sucessful flight?
thanks for the help.
05-25-2011, 07:59 AM
#2
RE: Pontoons
The pontoons should be about 3/4 the length of the fuse.
The step on the bottom should be about 1/2" behind the plane's natural CG
With the top of the floats level, you should have about 2 - 21/2 degrees positive incidence in the wing.
Only one way to find out if that engine is enough - Fly it
As for controlling it, you're on your own
The step on the bottom should be about 1/2" behind the plane's natural CG
With the top of the floats level, you should have about 2 - 21/2 degrees positive incidence in the wing.
Only one way to find out if that engine is enough - Fly it
As for controlling it, you're on your own
05-25-2011, 01:31 PM
#3
RE: Pontoons
I am in agreement with MinnFlyer. I just like the step slightly closer to the Aircrafts CG with that size airplane, that is the step about a quarter inch behind the CG.
Concerning that CG though. The CG should not change when on floats. In otherwords you should fly it at the same CG that it flys well at when on wheels.
This can frequently be accomplished on a typical installation by adding any ballast required to the bows of the floats (since this is what most often is required) bring the CG back to the same spot it ballanced at with the wheels.
This is the one time I reccommend not shifting components in the airplane but using lead in the floats.
The reason for this is you will now not have to rebalance the airplane now when changing between wheels and floats.
How Long are your Floats?
Concerning that CG though. The CG should not change when on floats. In otherwords you should fly it at the same CG that it flys well at when on wheels.
This can frequently be accomplished on a typical installation by adding any ballast required to the bows of the floats (since this is what most often is required) bring the CG back to the same spot it ballanced at with the wheels.
This is the one time I reccommend not shifting components in the airplane but using lead in the floats.
The reason for this is you will now not have to rebalance the airplane now when changing between wheels and floats.
How Long are your Floats?
05-31-2011, 06:38 AM
#7
RE: Pontoons
Floats. Bridges and party patio boats use pontoons. Aircraft use floats. ;-)
Note that the 4" measurement for flost tip to prop thrust washer given on the drawing will only work with .40 size models. The important measurement is to get the step 1/2" or so behind the C.G. The float tip to prop is what it is.
Note that the 4" measurement for flost tip to prop thrust washer given on the drawing will only work with .40 size models. The important measurement is to get the step 1/2" or so behind the C.G. The float tip to prop is what it is.
