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Mini Sea Duck

Boberticus

Active member
#1
50% Sea Duck here, because i have far too many projects going and I need another!!!

doing this to get something built for the Aprils showers challenge, and have always wanted a half sized Sea duck. This sucker should just be able to fit 6 inch props, with a 28 inch wingspan, aiming for a AUW of 400-500 grams, but I'm going to be pulling the paper off the inside of most surfaces, and not using hot glue, so maybe ill get it under 350. full sized one weighed 1100 grams, so a third the weight on a half sized plane would be sweet.

I resized all the slots to fit just the same as the large version, and I've tried to make it so that you can simply follow the full size build video,the only difference is that i elected to leave the wing whole and have the motor pods simply clamp on the outside lined up with the reference marks, and i combined the pontoons into one piece.

Planning on using some Racerstar 2306s, with some 30 amp ESCs and a 1500 4s battery, but any combo capable of spinning a 5 inch blade should do, not sure what that is in power packs. the full size doesn't seem to have a problem with power, and withe the average 2204 motor is capable of 500 grams thrust, i expect to be able to use this for hovering/3d acrobatics as well.

I originally meant to try and fit it to micro 110x motors, but they would complain with 5 inch props... I wonder how a 14 inch wingspan micro version would fly with a pair of 1407 motors and 3 inch props? that would easily fall under the 250 gram limit. Oh well, I've already invest a few hours into these plans, the least i could do is build one halfway through before losing interest and starting another project :)

im sorta posting this cause i cant find my Flash drive, and i need a way to get it printed off up at work. files are meant to be printed full sized, with a .05in overlap that gets cut off one side...

Version 1.3 with changes from the beta builders here:
 

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w1lp33

Active member
#4
The horizontal stabilizer is buried inside the wing :)

Otherwise looks good. I never got around to finishing shrinking the Sea Duck plans, so I'm eager to give this a shot. I'll post up how it goes when I get this cut out. Thanks for posting!
 

Boberticus

Active member
#5
a TYPO!!!!!! AAARRRRRRGGGGGGGGH!!!!!!!!!!!!!

dang it im at work not printing this right now!!!!

man i wish i had checked this before leaving,

tomorrow.
 

w1lp33

Active member
#6
Uhoh, gonna make it worse.... So I've printed it out, and had to make a few minor modifications/corrections. I list them here just so you're aware of them, not to nitpick or be a jerk:

1) No servo cutouts in the wings or spars
2) cutout in the bottom of section of the wing, that is there to do a C-Fold on the trailing edge isn't wide enough. It's one width of foam wide, should be two
3) Pontoons rear section, the piece that comes up the back and forms around the top of the pontoon, either the cutout size is in the wrong spot, or the foam section is a little too big, I had to trim it for the back of the pontoon to meet up correctly. I can post a picture if I'm (definitely) not explaining this well
4) Gonna need custom firewalls, the power pods at 50% are too small for the standard mini firewalls. That's not really an error, it's just the way it is at 50% :)
5) Cutout's for the vertical stabilizers to slot into on the horizontal stab are too small, will need to be opened up.
6)Hole will need to be cut into the wing and spar for esc wires to pass through booms into the fuselage, but those can be custom cut when building.

I think that's all I found. All minor little things, overall you did a really nice job. I've got all the pieces cut out, when I start getting it together I'll post some pictures. Thanks again for posting the plans :)

EDIT: One more I just remembered, no cg marks on the wings. But I suppose the CG may change a little anyways once shrunk down so that's not a massive issue.
 

Boberticus

Active member
#7
ah crapola, all of those things are simple mistakes, i didnt think someone would be building this so quickly... awesome feedback all duly noted,

the two matching wierd jagged things on the top left side of the "top section" page right beside the top fuselage part are meant to be power pods that slip into the fuselage tubes and sit flush on top of the wings, and flush with the front of the fuselage tubes

was planning on cutting a normalish sized firewall to cover the entire front of both the pod and the fuselage tube, attach the motor, and then glue that onto the motor pod and letting it dry, then slipping it into the fuselage tube and gluing that whole monstristy in place. then adding a NACA duck for airflow over the ESCs, with the wires roughting in behind the wing spar.

ill update the rest of that stuff tonight and have it on the plans as soon as possible
 

w1lp33

Active member
#8
Update as I started building. The slot in the pontoon that the leg goes into needs to be widened. The length is fine but the thickness is too narrow. It also needs to be widened where the leg slots into the wing. I cut a hole in the wing for the servo, and split the spar in two and trimmed it so it basically goes spar-servo-spar.

I’ve uploaded a picture of the piece on the pontoon that needs to be trimmed (this is post trimming)

Probably done for tonight, I’ll keep this thread updated as I build :)
 

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Boberticus

Active member
#9
ah i got everything fixed but that back/bottom section of that pontoon that i couldnt figure out flat, and the servo in the spar,

is it just almost a c fold so it needs to be wider? or is the gap in the wrong place entirely?

i think ill hafta build a pontoon to wrap my head around how to change it.
 

w1lp33

Active member
#10
Either the first gap is too wide, or the second gap is too far away. Basically the first square of foam that covers the bacj of the pontoon is too long and sticks up past the sides, so needs to be trimmed back.
 

w1lp33

Active member
#14
Update:

Got most of it together. Lookin good, thought the top fuselage portion that slides over the wing is gonna need some custom cutting and opening up of the wing channels, its a very tight fit with not a lot of "meat" left around the wing.

Pieces I had to mod slightly: The notch at the back of the booms that the horizontal stabilizer sits on had to be widened for the stab to sit flush, and the slots in the vertical stabilizers needed to be enlarged as well. Also the motor pods are not sized correctly, A-folded or B-folded they don't fit properly inside the front of the booms.

Got my aileron servo holes ready to go, pontoons installed, bottom of the fuse finished... Have to stop here for a bit till I get motors/esc before I can finish this build, cause they all gotta be installed before closing up the fuselage.
 

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#15
this is awesome man im at work right now but once i get home ill get the plans updated.

i think i had already fixed the vertical stab slots when you pointed out the horozontal stabilizer slots, if this is still the same first version print i think i got those but ill double-check, that back section of the booms is a easy fix, yet another simple mistake, and i thought i was being clever with the placement of that wing cutout, thinking it folded the other way, ill move them down a single width of foam so it sits flush with the inside of the roof like i intended. just getting to print this out today, hopefully will be joining you in the build shortly, maybe tonight :)

seriously though, thank you so much for the updates, You rock.
 

w1lp33

Active member
#16
this is awesome man im at work right now but once i get home ill get the plans updated.

i think i had already fixed the vertical stab slots when you pointed out the horozontal stabilizer slots, if this is still the same first version print i think i got those but ill double-check, that back section of the booms is a easy fix, yet another simple mistake, and i thought i was being clever with the placement of that wing cutout, thinking it folded the other way, ill move them down a single width of foam so it sits flush with the inside of the roof like i intended. just getting to print this out today, hopefully will be joining you in the build shortly, maybe tonight :)

seriously though, thank you so much for the updates, You rock.
Happy to help. This is my first go at beta testing a build ;-) Got my motors and stuff in today, so hopefully I'll have it finished in the next day or so. I figured the motor pods was just an issue of mixing an A for a B fold on the boom... Easy mistake to make, and an easy one for me to fix. Just gonna trace out the motor pods on a piece of foam and move the score lines to fit.
 

w1lp33

Active member
#17
Update: Got all servos installed. I settled on the elevator inside the fuselage for the elevator, as it's too big to fit in the boom like on the full size Duck. Seems to work good. I've noticed you don't actually need the motor pods at all, the front of the booms are basically already the exact size as an FT mini firewall, which is perfect. A 6" prop is definitely too big, but a 5" prop will work just fine.

Things I had to modify this time around: The bottom boom skins need to be cut. Because the booms don't go into the wing anymore, but sit on top, the part of the skin that goes under the wing doesn't meet up and is no longer necessary. So I cut it off and just kept the portion of the skin that covers the open bit of the boom. Again, see pictures :)

I forget if I mentioned in one of the earlier posts, that the tab at the top of the pontoon leg that slots into the bottom of the wing needs to be shortened. Currently it'll hit the spar, you need to trim a width of foam off the top for it to fit nice.

Basically I need a receiver and to do the pushrods for the ailerons and I can attach the bottom of the fuselage and my build will be finished. I'd call this a success, tho the fuselage is not gonna be pretty under the wing. But I'll make it work :)

Fingers crossed the cg will balance properly with a 2s or 3s battery!
 

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#19
i know right? i pulled the brains out of my 5 inch quad for a sub 250g racer build, but i didn't even realize that the plane would be perfect for 5 inch props untill the plans were done and i was looking around my workshop/bedroom taking stock on what i had that this would fly on.

funny enough, I have that exact firewall as a Stl file, i use that all the time, its probaly sitting like 3 feet from my computer, that's super convenient, I'll change the booms to just perfectly fit that, and keep a regular firewall on the plans for some plywood and a link to the printable one.

that servo placement for the elevator is clever, ill add a reference mark, a hole, and a note in the first post.

do you think pontoon arm tab needs shortened, or a second hole cut in the spar for a extra strong section of spar/pontoon? probably easier to just cut it short like you said and add a dab of glue on the end...

I'm most concerned on clearance between the battery tray and the bottom of the wing, do you think that s enough space to slip in a battery once its closed up, or does that tray need to be dropped?, I don't think the height of it matters too much, and I didn't think about how much smaller the compartment would be when i just shrunk it and forgot about it. give it a look before you glue it together and let me know if that part needs to be deeper.
 

w1lp33

Active member
#20
I was able to slide in a 3s 850mah battery in after assembly.

Definitely need to change the aileron servos. Need to cut a chunk of spar out and lay the servo flat, with the servo as shown in the pictures, the angle of the pushrod is terrible.

Also, not a critique but a suggestion: the paper border on the upper portion of the fuselage that covers the seam with the bottom fuselage, is make it longer. It’s very thin and hard to work with when merging the fuselage.

The booms as is fit that firewall perfectly, no need to change anything, just disregard the motor pod pieces entirely

Plane seems to balance good with a 2s 650mah-3s 850mah. The 3s seems kind of on the nose heavy side, but it’ll have more than enough power on 2s with 5” props.