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Old Aug 10, 2010, 08:21 PM
Electric Coolhunter
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United States, TX, Fort Worth
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I might also try the Rain-X treatment to reduce the surface tension on the hull...it seems to really help the sub micro Drake flying boat models with the surface tension effects on those 17 gram models....
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Last edited by Thomas B; Aug 10, 2010 at 08:35 PM.
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Old Aug 10, 2010, 10:35 PM
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I have 10 float planes , large underpowered ones , small overpowered ones and some in between , all ROW .

The "surface tension" thing is way overrated , if there is a dead calm , do a couple of circles to produce some ripples , then go for it .
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Old Aug 10, 2010, 10:41 PM
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Old Aug 12, 2010, 09:06 AM
Excellence thru mistakes
Sanibel Island. FL
Joined Sep 2002
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When I was in the Navy many, many years ago a fellow officer had flown the Martin Mars. It had the same "sticking" problem. In that case Martin's mod was a standpipe just forward of the step to allow air in to break the suction.

Another method was related to me by a Hellcat pilot who bluffed his way into taking a Catalina out when he was temporarily in San Diego. He needed the hours to get his flight skins, though he had ZERO experience in seaplanes. Anyway he encountered the same problem and couldn't get enough airpeed to break loose. He kept yanking back at full power and settling back down until he finally got it off. Experienced Catalina pilots probably used flap settings to generate enough lift.
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Old Aug 12, 2010, 10:57 AM
Parkcityflier
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Park City, UT, USA
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No flaps on a Catalina, at least not on the one that I flew.
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Old Aug 12, 2010, 12:02 PM
Electric Coolhunter
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United States, TX, Fort Worth
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Venting the step was done on many of the full scale Berievs, and lots of other seaplanes as well.

That is on my list to try, if all else fails.
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Old Aug 12, 2010, 12:05 PM
Electric Coolhunter
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United States, TX, Fort Worth
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Venting the step was done on many of the full scale Berievs, and lots of other seaplanes as well.

That is on my list to try, if all else fails. Was discussing a postiive pressure system for venting the step with a local modeller, Joe Jopling, last week, but he thinks, correctly, that all that is needed is the vent at the step, connected via tube to a vent on top of the model somewhere.
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Old Aug 22, 2010, 12:27 AM
Excellence thru mistakes
Sanibel Island. FL
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Thomas B

Two more thoughts on the stickiness problem.

The sharpness of the aft end of the step is critical. Any radius adds significant drag. A quick and dirty test is to take some thin stiff plastic (smooth surface ABS would be good)and temporarily attach it with contact adhesive with a slight overhang aft of the step. Scotch tape the leading edge of the plastic so the water pressure doesn't peel it off.

The other is to add a wedge to increase the angle of the step for a short distance. The idea is to reduce wetted surface when the plane is taking off.

If all else fails, more power is often the answer.
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Old Aug 22, 2010, 01:46 AM
Electric Coolhunter
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United States, TX, Fort Worth
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Quote:
Originally Posted by Corky Boyd View Post
Thomas B

Two more thoughts on the stickiness problem.

The sharpness of the aft end of the step is critical. Any radius adds significant drag. A quick and dirty test is to take some thin stiff plastic (smooth surface ABS would be good)and temporarily attach it with contact adhesive with a slight overhang aft of the step. Scotch tape the leading edge of the plastic so the water pressure doesn't peel it off.

The other is to add a wedge to increase the angle of the step for a short distance. The idea is to reduce wetted surface when the plane is taking off.

If all else fails, more power is often the answer.
Well aware that the step must be sharp and mine is. One of the water trials has bee done with a 2" long and 1/4" deep step addition, all sharp edged.

I am running the EDF 40s about as hard as is practical, so no real way to add any power. Part of the fun of getting this to work is the restriction/power limit of the small EDF units.

Will be trying some other things and have two more float fly events coming up...will report back.
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