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Old Feb 18, 2012, 11:05 AM
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serjuro's Avatar
Romania, Europe
Joined Aug 2009
278 Posts
Hello to all !
In ROmania also a Twin is born...
Turnigy 2213 1000kv motors, 25A Esc, 3s1600mAh lipo(nanotech) 2 pcs.
Instead of CF spars, I've used 2 double closed beams from 8x4mm spruce.
I maybe should mount some wheels because I have no near pond or lake to fly on water...
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Old Feb 18, 2012, 08:12 PM
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Wormboy's Avatar
Australia, WA, Madeley
Joined Jul 2011
650 Posts
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Originally Posted by mavlo77 View Post
I see. It's looks cool anyway!
I also plan to make ailerons, so I also will minimize the dihedral. Actually I even was thinking of some nice flaps for scale like effect. But I will only do this when it fits and I can make a very light single servo solution for this.
I was thinking about mixing flaperons... Just because I can. Also I am planning to mix in differential thrust to the two motors for on-water turning. I know it doesn't really need it but it's more about the exercise of making it work
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Last edited by Wormboy; Feb 18, 2012 at 10:05 PM.
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Old Feb 18, 2012, 10:08 PM
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Australia, WA, Madeley
Joined Jul 2011
650 Posts
Looks good serjuro!

Reckon you will want to mount some wheels if you're flying from land. I don't know how the bottom of the fuse will hold up to repeated belly landings.

I notice you left off the engine nacelles. Any parturiticular reason? Or you just didn't like them?

Your motors look about right. I went for the turnigy 2830 920 kv. Pretty similar motors but yours will handle slightly more amps and turn slightly faster. Ive had the SK3s before and have found hem to be smooth and quite quiet. Hopefully these are no exception.
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Old Feb 19, 2012, 02:30 AM
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The Netherlands
Joined Oct 2008
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Originally Posted by Wormboy View Post
I was thinking about mixing flaperons... Just because I can. Also I am planning to mix in differential thrust to the two motors for on-water turning. I know it doesn't really need it but it's more about the exercise of making it work
Yes, that's also my challenge: make it work. But only if it's realistic. So if the flaps addition gives a higher stall speed because of the extra weight, I won't do it. Good point about differential thrust. I also will probably add the 2nd motor on a separate channel and use the turning knob on the Tx to control the balance, and use a switch to enable mixing it with the rudder control (for water taxi in wind).
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Old Feb 19, 2012, 05:11 PM
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Australia, WA, Madeley
Joined Jul 2011
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Originally Posted by mavlo77 View Post
Yes, that's also my challenge: make it work. But only if it's realistic. So if the flaps addition gives a higher stall speed because of the extra weight, I won't do it. Good point about differential thrust. I also will probably add the 2nd motor on a separate channel and use the turning knob on the Tx to control the balance, and use a switch to enable mixing it with the rudder control (for water taxi in wind).
I think you will be ok with weight, even if you add the extra weight with flaps. looking at my wing loading so far I think it will be a real floater. Do you think you'll need the turning knob to balance? Iwas planning to just mix it to the rudder for taxi and then to a switch so I can turn it off during flight. Any slight difference in the speed of the motors should be able to be trimmed out with a bit of rudder
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Old Jul 31, 2012, 08:33 PM
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Australia, WA, Madeley
Joined Jul 2011
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PTIIXL finished and ready for maiden tomorrow.
I'll post a piccy up before I fly in case I crash&burn.
I've added fixed tricycle gear initially to get her off the ground (and something to stand her on while I build) but if all goes well I'll take them off, seal her up and fly her off the water as intended.

Any progress on yours Mavolo?
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Old Aug 02, 2012, 04:38 PM
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The SKY MAN's Avatar
uk/england
Joined Jun 2008
341 Posts
Good luck on the maiden
following with intrest


Iain
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Old Aug 03, 2012, 04:35 PM
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ak68's Avatar
Nederland, ZH
Joined Dec 2011
624 Posts
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Originally Posted by Wormboy View Post
PTIIXL finished and ready for maiden tomorrow.
I'll post a piccy up before I fly in case I crash&burn.
I've added fixed tricycle gear initially to get her off the ground (and something to stand her on while I build) but if all goes well I'll take them off, seal her up and fly her off the water as intended.

Any progress on yours Mavolo?
Good luck on your maiden Wormboy! Looking forward to pic's and video as educational material.
I'm glad to see some activity here concerning PT II.
I'm slowly building a light one. The wing is ready and standalone so it can be used for different fuselages. Span 1200mm. Differential throttle. Planned AUW 450 grams.
Mavlo might come up with a bigger PT later this year.

AK68
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Old Aug 06, 2012, 07:45 PM
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Australia, WA, Madeley
Joined Jul 2011
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Thanks for the encouragement folks.
It doesn't matter how many planes I build, maidens always get my adrenaline going and this one was no exception.

A couple of pre-maiden pics, ignore the port-side list, that was just a bit of bent undercarriage and evens out easily:

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OK. The maiden.

first flight went well, no need for nerves at all.
I had a couple of kinks to work out, the CG was a little bit too far aft so she was slightly tail heavy and the port-side motor only throttled up to 50% while the starboard had full range. No matter, they were easy fixed, just moved the battery forward and fixed the programming error in the Futaba's horrible programming mix menu.

Second flight was pretty much spot on. I cruised around for a couple of minutes. She managed solid vertical (not unlimited) and a little inverted. I did notice she was crabbing a bit so I think the port-side motor is still not quite pulling its weight. I was right about her bing a real floater.. she lands very slowly and lightly, even easier than my Polaris believe it or not.

Third flight was not so flash. Buoyed by my previous success I got a bit cocky and stayed up too long. The ESCs hit LVC and she dropped out of the sky rather rapidly. In my other planes I am used to the thrust getting a bit spongy which is a clear signal to get on the ground quick. This time with the twin motors it seemed to be full thrust then.....nothing. Total LVC.

Damage was minimal. I had designed a weak point into the wing mount to allow it to absorb some of the energy in the event of a crash (a wise move as it turns out) . Thankfully a bit of a pushed in nose and a couple of dings in the fuse from the props was the only damage. nothing serious.

She shall fly again this weekend! (as soon as I fix the problem with the portside motor)
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Old Aug 07, 2012, 02:46 PM
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Nederland, ZH
Joined Dec 2011
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Thanks Wormboy for posting the inspiration. Congratulations with the succesfull maiden.
Nice build with 3 bladed props.
Any chance posting a pic of the provisional undercarriage?
Sudden LVC? Are you sure it was not overtemp of the ESC in your third flight? Does PT II need any way of cooling like the polaris does?
Wish you a succesfull and uneventfull weekend!

AK68
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Old Aug 14, 2012, 03:41 PM
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ak68's Avatar
Nederland, ZH
Joined Dec 2011
624 Posts
Another Puddle Twin sees the light:
spec: 6 mm depron.
3 mm carbon strip as spar
2 * turnigy 2204-14T 19 gram motors
2 * HK 12 A Blue Series ESC
1 Orange 6Ch 2.4 GHz Rx
1 Turnigy V-Tail Mixer 200 steps.
4 * HXT500 5 gr servo's
8*4.3 prop and counterprop
span 118 cm.
AUW 530 grams incl 2S1000 batt. Excl extra watersupply after landing
Wing transferrable to other (future?) fuselages.
Some attached pictures of the build.

Still to do: rearrange batt lead to allow a more forward position for the battery.
Make magnetic hatch as front window.
fix wings to prevent sideways (out of center) movement.
protective tape on bottom of hull
decals for visibility

Did kind of a premature maiden yesterdaynight. Partly because the weather was so inviting and partly because there was an experienced spectator available. Thanks Mavlo77 for sharing this maiden.
Thanks R.Merk for sharing your design. Given the design and the maiden results I would expect this thread to be more popular.
Wormboy: Hope your maiden was a positive surprise. Mine was. I'm happy. Keep you updated on the maiden soon.

AK68
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Old Aug 14, 2012, 03:58 PM
Smells like SCIENCE!!!
ibillwilson's Avatar
Canada, ON, Toronto
Joined Jun 2012
341 Posts
Quote:
Originally Posted by ak68 View Post
...
Given the design and the maiden results I would expect this thread to be more popular.
...
I agree. I just discovered this thread recently, and I've been looking at flying boat projects for weeks.

If this thread was under "Foamies (Scratchbuilt)", there'd be a lot more action. Go there and look at the thread for the SeaBB to see what I mean. I ended up building something using the SeaBB plan as a general guide... but I converted it to a twin. I'm happy with what I built, but if I'd seen this thread much earlier, I might have built a Puddle Twin XL instead of hacking the SeaBB like I did.

http://www.rcgroups.com/forums/showthread.php?t=954868
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Old Aug 14, 2012, 04:56 PM
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ak68's Avatar
Nederland, ZH
Joined Dec 2011
624 Posts
Update: Some pics of the result so far. Turning on a dime on water because of differential throttle. The inner wingtip even moves backwards... That is thight. Video to follow somewhere week.
No expo programmed yet on DX6i.

Behaviour:
1/4 throttle: on the step. Sponsoons not dragging at all unless forced into the water with ailerons.
30-40% throttle: flying in ground (water) effect.
50% and onwards: reaching for the sky.
Taxiing went fine. Tracking very well. Getting on the step very easy. Unexpected easy separation when applying slightly more throttle. And then .. oops, you are flying!! gracious turns. Good lift.
It simply did not want to come down unless nearly cutting the throttle. (Needs two clicks of downtrim). So I did cut the throttle and lined up for final. All smooth and (too) slow until some two feet above the water: flaring.... loosing speed ....stall!! Right hand roll and nose in. Pilot error. Other than taking in a pint of water through the open front window there was no damage. After draining tried again with taped front window. Guess what? Managed to do the same again.
In spite of the funny landings: I'm very very pleased with the overall result! Next time I'll try airborne rudder turns, vertical performance, roll, loop, etcetera before I dunk it.


AK68
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Old Aug 15, 2012, 02:33 AM
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serjuro's Avatar
Romania, Europe
Joined Aug 2009
278 Posts
XL from ROmania...

NICEEEEE, makes me try to build a new one for me.........
The pics from the first build are here :
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