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Old May 17, 2012, 10:17 AM
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Question: I assume the ski hull has to be sealed to prevent water from entering. What is the best sealer for this? What do you guys use? Mike
Mike, Note that I made the elevons shorter. They are very responsive as you scale down.
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Old May 17, 2012, 11:43 AM
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I am building a 36 inch sea dart with several mods, like designing in a wing strake and using a k2 KF wing mod, and a 9x5 prop. I'll post pics when I'm done. Mike
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Old May 17, 2012, 11:58 AM
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I'm looking at a 24" wingspan version. Would like to use a 2S lipo (since I've got a lot of them). Do you think that a 1700 KV Blue Wonder motor with an 8" prop be OK ?
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Old May 17, 2012, 02:53 PM
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These planes aren't simple to make. The ski hull is difficult to fab just right and seal. I'll have to test how well it's sealed somehow.
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Old May 17, 2012, 04:00 PM
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Originally Posted by Flyboy Steve View Post
I'm looking at a 24" wingspan version. Would like to use a 2S lipo (since I've got a lot of them). Do you think that a 1700 KV Blue Wonder motor with an 8" prop be OK ?
Will you be able to get an 8" prop in the tail? I would lean more to a 7x5 or 6x5 prop.
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Old May 17, 2012, 04:50 PM
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I have redesigned the tail slightly to accept a 9x5 prop, using my turnigy 3536-1400 motor with the 9/5 will give me 2.9 lbs of thrust and my expected weight all up is 2.25-2.5 lbs. I have also redesigned the fuselage to take a far forward battery to balance it off. So far so good.
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Old May 17, 2012, 09:10 PM
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Originally Posted by Mike St View Post
I have redesigned the tail slightly to accept a 9x5 prop, using my turnigy 3536-1400 motor with the 9/5 will give me 2.9 lbs of thrust and my expected weight all up is 2.25-2.5 lbs. I have also redesigned the fuselage to take a far forward battery to balance it off. So far so good.
Sounds like a winner. Keep us posted on your progress.
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Old May 18, 2012, 02:28 PM
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On my 24" plane, I was thinking about moving the motor up a bit to accomodate an 8" prop. Alternatively, I could use a THREE bladed prop at say 7". Keep the same pitch -- i.e. 7 x 6 ??
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Old May 18, 2012, 06:10 PM
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On my 24" plane, I was thinking about moving the motor up a bit to accomodate an 8" prop. Alternatively, I could use a THREE bladed prop at say 7". Keep the same pitch -- i.e. 7 x 6 ??
I would try to keep the thrust height and angle as close to the plans as possible. 3 blade sounds good.
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Old May 18, 2012, 06:32 PM
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I had to lift the motor a little to increase the prop size, but I also widened the slot substantially so if it turns out a need more down angle, I have enough slot width to install shims to adjust the angle. Hopefully, I'll be close enough to make a minor adjustment. You simply have to be brave enough to experiment to make a better mouse trap.
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Old May 18, 2012, 11:13 PM
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I had to lift the motor a little to increase the prop size, but I also widened the slot substantially so if it turns out a need more down angle, I have enough slot width to install shims to adjust the angle. Hopefully, I'll be close enough to make a minor adjustment. You simply have to be brave enough to experiment to make a better mouse trap.
On my 19" and 43" wingspan I stayed true to location and angle and both fly great.
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Old May 24, 2012, 07:53 PM
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Advanced Sea Dart

Here's my just completed 36 inch Sea Dart, featuring a 9x5 prop, Turnigy 3536-1400KV motor, producing 3.25 lbs with a three blade and 3.0 lbs with a 2 blade. All up weight with 3 S 2200 came out to 2.5 lbs. Also full span elevons, combined air and water rudder, K2 wing mod, and an enlarged slot to totally eliminate slot noise. Also have a modified long fuselage for placing a battery very far foward and a slight strake to the wing. Made from pink HD 1/2 inch foam, coroplast, laminated blue foam (rudder and elevons), and depron K2 airfoil. I call this an advanced Sea Dart. Will fly it this weekend if the weather holds. Servos waterproofed with vaseline. Mike
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Old May 24, 2012, 11:14 PM
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Originally Posted by Mike St View Post
Here's my just completed 36 inch Sea Dart, featuring a 9x5 prop, Turnigy 3536-1400KV motor, producing 3.25 lbs with a three blade and 3.0 lbs with a 2 blade. All up weight with 3 S 2200 came out to 2.5 lbs. Also full span elevons, combined air and water rudder, K2 wing mod, and an enlarged slot to totally eliminate slot noise. Also have a modified long fuselage for placing a battery very far foward and a slight strake to the wing. Made from pink HD 1/2 inch foam, coroplast, laminated blue foam (rudder and elevons), and depron K2 airfoil. I call this an advanced Sea Dart. Will fly it this weekend if the weather holds. Servos waterproofed with vaseline. Mike
Be careful with that rudder. It is 3x the size it needs to be. It will generate a lot of roll. Get to altitude before you try it. The Dart flys well on elevons only. Looks like you could use a little more down thrust vector. You will probably get some pitch down on power application with the present setup.
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Old May 25, 2012, 12:53 AM
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It's hard to tell by the pics, but the motor is pitched per the drawing and if I need more, I'll use a shim to add a couple more degrees. The rudder is also an air rudder. After flying many planes over the years, I prefer a rudder to assist in turning and better overall control, although a jet can operate fine without one as you state. I want to improve slow flight control. After designing many planes, my research has shown that a delta wing flies better slow with a strake or canard.
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Old May 25, 2012, 01:35 AM
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Originally Posted by Mike St View Post
It's hard to tell by the pics, but the motor is pitched per the drawing and if I need more, I'll use a shim to add a couple more degrees. The rudder is also an air rudder. After flying many planes over the years, I prefer a rudder to assist in turning and better overall control, although a jet can operate fine without one as you state. I want to improve slow flight control. After designing many planes, my research has shown that a delta wing flies better slow with a strake or canard.
Great to hear the thrust is per the V2 drawing. I had the same thoughts reference the rudder when I built mine and made mine large like yours. It was too effective at high and low speeds and generates more roll than you can imagine. Just be cautious; that rudder will roll you upside down before you can respond. Will be interested in your flight report. Best.
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