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Mini Sea Duck

#1
I would like to build a Mini Sea Duck but I've never cut my own foam. I've only build a mini Arrow and a mini Dart and I got the foam pre-cut from Flitetest . I'm guessing that I would get the plans from Flitetest and shrink them down and cut them by hand, right? My problem is that I don't know how to do this so I was wondering if anyone here could give me some pointers. What software applications do you use to shrink plans down? Do you cut the foam by hand or is there an online service that would cut it for me if I sent the the plans? Sorry for the newbie questions. I've never scratch built like this before.
 

Hai-Lee

Old and Bold RC PILOT
#2
I would like to build a Mini Sea Duck but I've never cut my own foam. I've only build a mini Arrow and a mini Dart and I got the foam pre-cut from Flitetest . I'm guessing that I would get the plans from Flitetest and shrink them down and cut them by hand, right? My problem is that I don't know how to do this so I was wondering if anyone here could give me some pointers. What software applications do you use to shrink plans down? Do you cut the foam by hand or is there an online service that would cut it for me if I sent the the plans? Sorry for the newbie questions. I've never scratch built like this before.
You can scale the plans when you print by changing the scale in acrobat reader for the print.

Next you cut out the pieces and score the fold lines. If you have a balsa stripper then you can do the fold channels using the balsa stripper with it set to the material thickness.

It works for me!

Have fun!
 
#3
I was going to start this project but I realized that I have no idea what type of foam to use. I did order from rcfoam.com back in the day but they seem to have gone out of business. Does anyone know where I can get foam that would be suitable for a project like this? Flitetest does sell foamsheets, but the sheets are only 20"x30". The wingspan for this plane is going to be about 1 meter so I would probably need 30"x40" sheets of foam. Would 5 mm foam be too thick? Or would 3mm be more suitable for a project of this size? Where do people get foam for their scratch builds these days?
 

SquirrelTail

Well-known member
#4
I was going to start this project but I realized that I have no idea what type of foam to use. I did order from rcfoam.com back in the day but they seem to have gone out of business. Does anyone know where I can get foam that would be suitable for a project like this? Flitetest does sell foamsheets, but the sheets are only 20"x30". The wingspan for this plane is going to be about 1 meter so I would probably need 30"x40" sheets of foam. Would 5 mm foam be too thick? Or would 3mm be more suitable for a project of this size? Where do people get foam for their scratch builds these days?
The 20x30 foam is fine. The wings were designed to be built in halves, so it works. I get my foam from the dollar store.
 
#5
When you get hoing on it; I for one, would love to see what you come up with. I've got a friend that wants to build the full size from the speed kit. I think it would be hilarious to show up with a scratch built mini-duck (or 3) if they fly ok.
 

Hondo76251

Well-known member
#6
Mini sea duck does sound like a good idea!

I use dollar tree foam board mostly. I've found it at some Walmart's too just watch that you get the lighter foam board stuff and not the heavy kind.

At a dollar a sheet dont be scared to just start cutting away!

A good cutting board helps a lot and I prefer the small (pencil sized) exacto knives with the #11 blade...

Here's a build video I did with a design I just sorta made up as I went... I doubt you'll need the hand shaped airfoil wing or the carbon fiber spars but it should demonstrate that it doesn't take much to build something out if foam board even without a speed build kit!

 
#9
@superhappyfun you ever get a mini sea duck in the air? Curious how it went...
Yes! I did eventually get around to making this. It took a while though. I downloaded the PDF plans and using Adobe Acrobat Reader cropped each section of the plane I wanted to build and shrunk the plans down to 72% and cut the foam using a box cutter, which resulted in a 1054mm wingspan. I'm not very good at scratch building so my cuts were kind of jagged in some cases and I had to cut the hole in the fuselage that the main wing passes through a little wider because scaling the plans down did produce some "fitting issues". I think this was because I used 5mm foam from the Dollar Store, which is a bit thick in my opinion and when you scale down plans but keep the foam the same thickness it can cause these issues. I also reinforced the wings with a balsa wood rod and filled in some of the gaps with Great Stuff expanding foam to keep water from getting in. I reinforced the bottom of the plane with some 1/64 mm plywood I picked up at an arts and craft store and I sealed the seams of the plane with coffee filters and glue (kinda like using paper mache). For electronics I used Emax 4.3 gram servos (ES9051), two EMAX 1806 2280kv motors on 6030 props powered by two Arris Blheli 20amp ESCs. With these props on max throttle I pulled about 12amps per ESC, or 24 amps total. I powered this using a Lumenier 1300 mAh 3S battery, which gave me about 5 minutes of flight time. I used a lemonrx receiver and set my controls up to use flaperons. There is no particular reason why I chose this electronic setup though, I just happened to have these parts lying around, that's all.

For me it flies well, but my opinion on what a good flier is might be different from everyone else. I didn't want this to be a pylon racer or a 3D plane and it's not. The purpose was to recreate a smaller version that I could land on the pond in my neighborhood with docile flight characteristics. My worries were that this wouldn't fly at all because I did a lot of glueing and reinforcing, AND I used thicker foam. In the end, this bird was heavy, the full build weight with all electronics and no battery is 560 grams, which is probably 100 grams over where it should be, but in spite of that the power setup got it into the air just fine. It was a bit of "clumsy flier" though, but this setup gives it plenty of power and a straight up vertical was achievable because at max throttle each engine puts out about 450-480 grams of thrust or 900-960 grams total.

The remaining tasks are to paint it. I'll probably coat with some water based polyurethane on the main fuselage and a final coat of paint using the classic Sea Duck paint scheme. I might skip the motor cowls too, but I'm really not sure. If I get a chance I'll try to post a flight video, but I don't have a great camera setup for this so I don't count on that happening anytime soon, maybe I can coax my wife into coming out to the flying field and getting some footage using a phone camera.

If I had to do it again I would have tried to find thinner foam, probably 3mm would have been better and I might have been more conservative with the glue and not used the coffee filter approach, not that the coffee filters added that much weight, but I think it was a waste of time for something that could have been achieved more easily simply by using hot glue.

Attached are some pics from various parts of the build process. Hope this helps!
 

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#11
I didn't use 3mm, I used Dollar Store foam, which is about 4.5-5mm. I would have used 3mm if I could find it. No one that I know of makes it which is a real shame. There is a video here were a guy explained why we can't get 2-3 mm depron foam anymore and he suggested some alternatives, but I haven't tried them yet.
 
#13
i can remember when i was a kid in the late 90s growing up in rural Kansas, a single sheet of 3mm Depron was like 20 bucks shipped, 30 in the local (within 50 miles of me) hobbyshop, i remember seeing on a newsletter that became RC groups fourm, people building huge depron planes with multiples of relatively cheap 5 euro sheets in Europe, just so disappointed i couldn't afford to even try to participate. I see comments now like its some sort of great foam wasteland in Europe and the Americans have the upper hand with our $1 DTFB Adams Rediboard. Oh how the turn-tables!

Now its a Dollar a sheet and its already paper backed on both sides. For 2 bucks, you can even get some premium board thats waterproof!!! made in the USA!!! frigging game changer. i hate seeing all the other folks have to cut back on their building, but i currently have a stack of foamboard in my closet that would equal my rent if it was in Depron, and I paid like 30 bucks. Way less disappointment in crashing something too, or ruining supplies trying out something weird that costs cents instead of dollars in materials.