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Old Nov 07, 2010, 03:14 PM
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Renton WA
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seamaster tip floats revisited

I am in the process of getting an old seamaster back in the air.
I had flown it electric a few years ago, but the orig builder had gone a little heavy, and so it always needed to fly faster and used more power than I really liked for an electric. The other thing he had done was leave off the rounded wing tips, added 2" alerons for a 13" chord, and stepped up the tip floats to 2". This left it with a 55" wing. As most of you know, unlike conventional tip floats, the seamaster uses floats glued directly to the wing. This works fine, but I don't really think it's fair to count that part of the wing as providing lift since it's no longer shaped like a wing, it's more like a little fuse. Maybe there's some winglet benifit, but I just don't know. So (55"-5" fuse - 4" tips X 13" chord = 598 sq inch usable wing and a flying weight of 6.8lb. or 26.2oz per ft of wing. Not unresonable, But I would like a little more wing to make it more floaty.

I decided that since I have a nice flat wing end to bond to, that a set of tip floats that go on the wing end rather than under the wing would be a quick way to increase effective wing area without having to tear into the wing or start over. I am going to make them out of 1.5" blue foam and just cover them with packing tape. This should gain me 52sq in of wing, or almost 10%

What do you think? Trying to figure out how best to attach them.
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Old Nov 07, 2010, 09:25 PM
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The "factory" plan for the tip floats was to attach them with Velcro. Many found this less satisfactory than some other methods.
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Old Nov 07, 2010, 11:32 PM
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Renton WA
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Since I am not planning on anything other than water flying, I think something more perminant would work fine. At least on this one, the joint between the float and the wing was never very smooth, there were always some gaps. My flat wing end will be much easier to get a tight fit, but I will have shear loads too. Maybe Gorilla glue??
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Old Nov 08, 2010, 12:13 AM
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Crossville, TN
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I assembled one of the ARFs for a friend...used double stick tape that the RC car guys use for servo's, etc. No more lost tip floats.
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Old Nov 08, 2010, 09:19 AM
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Gorilla glue is light and fills gaps, but on the off-chance that the plane ever needs to be repaired or re-covered, gorilla glue is a cast-iron B*TCH to remove without destroying those components to which it is bonded.

Art's suggestion of servo tape is a good idea.

I have just taped styrofoam tip floats to the wing with packing tape. If you plan ahead and use kraft-colored trim on your plane it can look pretty good!
Here's my Dover Darlin' I designed 8 years ago. You can see the packing tape. I rationalized that these were "prototype" floats.
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Old Nov 08, 2010, 10:40 AM
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I predict you will not see any real difference by moving the tip float from the lower surface of the outer wing to some offset position below the wingtip. The wing area you gain will likely not be effective wing area, as the tip losses there, especially on a wing with a squared off wing tip, will likely offset any gain.

The tip floats, in spite of taking up some wing area, are likely helping more than hurting. They act as a air dam against the airflow on the bottom of the wing going around the wingtip to the top of the wing.
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Old Nov 08, 2010, 11:53 AM
Garry
Tumble weed country Eastern Washington
Joined Aug 2004
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On my Seamonster the tip floats are about the same as the Seamasters and I just use clear silicone to attach them to the wing, I haven't lost one yet.
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Old Nov 08, 2010, 02:22 PM
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After spotting the thread title, I started reading the first post, and then checked out some pictures of the Seamaster.......

Then continues reading the posts, and.........I ain't the Martin Seamaster after all,
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Old Nov 08, 2010, 07:29 PM
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Canada, ON, Windsor
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The float location as designed helps immeasurably during takeoff and landing due to the fact they force the capture of air beneath the wing, greatly adding to "Ground Effect".

My resurrected Seamaster is flying fine in excess of 7lbs with the stock floats, which are attached by the stock method fore and aft with plastic tabs. This allows for removal for normal "Dirt" ops, but I found I never need to fly without them.

I added small plastic tip tabs to the bottom outboard of each float to prevent scuffing on hard surfaces. So far only flown from grass.

I have the originally installed Fox 50 powering mine, now undergoing mods to adapt a quieter muffler. With your weight a good power option would be the OS 55AX. Just be careful with the prop clearance. I had to run a cut down 11/8 on mine.
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Old Nov 11, 2010, 11:22 PM
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Renton WA
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Wow, 7 lb seems like a lot, but I guess it's just a mater of speed.

here is what I came up with. I was origionally going to just use one piece of 1.5" foam on each side, but I decided to add another 1.5" thickness cut to the airfoil shape. This allowed me to run clear tape around the wing joint in addition to double backed tape on the ends. The end result is 60.5" overall. The floats were wraped with red packing tape. The end result is ~700 sq inches instead of 600, at almost exactly the same weight. I am using a Eflight 32 and a 4cell 3000mah pack. I also have a 3600mah pack for longer flights. The prop is a 12X6 APC thin electric which gives a measured 70oz of thrust static at 40A.

I was surprised how much quicker this is to jump off the water. I am more used to electrics, and lighter wing loaded planes. The seamaster always felt a little heavy in the air, and needed more power and speed than I liked. I enjoy nice slow touch and go's and flying low and slow as well as mild acrobatics. With the new floats, the seamaster can really slow down on landings and take off much slower. The only thing I really miss is the high speed power slides. The origional would do huge drifting figure 8's at pretty high speed. This version will still power slide, but I have to be carefull or it will take off mid slide, or especially in the center part of the 8. Top speed seems about the same, the rear of the float is much more aerodynamic that before, which probably makes up for the slightly longer wing. I tried to get it to stall when landing, and while I'm sure it can be done, I just reach full up with it slowly mushing down into the water. There is no tendancy to drop a tip.

I totally agree that the floats are acting like winglets, catching the air and making the wing more effective, esp close to the ground. My Mariner (RIP) was about 10% lighter than the seamaster, and a lot of fun, but it needed a lot more speed off the water, and didn't float like this one does now.
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Old Nov 12, 2010, 09:12 AM
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Nicely done! Those look to be "cleaner" than the original floats which I am sure explains the unchanged top speed. Also I think the curvature of the inner side redirects your vortex much as the Hoerner tips on a Cessna, capturing the high-pressure air under the wing.
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Old Nov 12, 2010, 12:27 PM
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Renton WA
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Thanks!, here is a very short video of my new floats in action. This is a little lake I live on in Wa. If anyone is in the Renton area and want's to fly on a Sunday, let me know. Due to noise, I only fly electric.

THe landing is a little skippy, it will land slower and cleaner, but my 9yr old camera operator has a limited attention span. it is available in HD too!

Seamaster electric seaplane with new tip floats (1 min 11 sec)
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Old Nov 12, 2010, 10:24 PM
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Watced the vid and it looks like a great flyer. Only thing odd I noticed was the tendency to plow the nose down on take off.
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Old Nov 13, 2010, 12:31 AM
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Renton WA
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Not sure what you mean, at lest with the seamaster and mariner I start with a neutral elevator and then give the barest nudge up as it starts to break free. With a seawind, polaris, or donald, some up is needed to stay stable, then relaxed once in the air. I know some people always take off with a lot of up, but it really isn't needed with the seamaster, at lest in calm conditions. If I give full throttle and up, it will take off in about 45ft, but it really isn't my style on water.
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Old Nov 13, 2010, 07:37 AM
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At approx the 15s mark you watch the tail lift and nose dig down into the water. This has to be a result of the very high thrust line right at the pitch center. Just can't remember seeing it before.

Forgot to mention, one beautiful looking flying location you have there.
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