Canadair CL-415 Super Scooper Firefighting Seaplane with Plans and Video - RC Groups
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Nov 23, 2014, 05:49 PM
Letís eschew obfuscation.
scott swanson's Avatar
Build Log

Canadair CL-415 Super Scooper Firefighting Seaplane with Plans and Video


I’ve been working on a scale CL-415 and have recently completed some flights. It flies very well! The Super Scooper has a 56” wingspan, removable wing, twin engines, is built of pink FFF, and can scoop and dump water.

I was hoping for a more colorful title for this thread, but Warhead_71’s “Big Pink Beaver” just seemed to be more tasteful than “Big Pink Super Scooper”.

The CL-415 is a standout modeling subject for several reasons:
1. It has almost no compound curves, making it a perfect project for foam.
2. It has awesome winglets all over.
3. It comes in lots of bright color schemes, most using fire engine red and cub yellow.
4. Speaking of fire engines, it has flashing red lights.
5. It can scoop up water and dump it on forest fires (or the neighbor’s dog, whichever is more appropriate).

415’s have been a popular modeling subject. There are several commercial versions on the market, and at least two have been built in foam and described here in RCG: Sopwith Mike’s 48" 215 at https://www.rcgroups.com/forums/show....php?t=1158175 and Nibbio’s 50" 415 at https://www.rcgroups.com/forums/showthread.php?t=356484.

Specs:

Wing Span: 56 in.
Wing Area: 380 sq. in.
Flying Weight: 28 oz. without water (but I haven’t painted it yet)
Water Load: 19 oz. by weight
Battery: 2200mA 3S LiPo
Motor: 2 Turnigy Aerodrive SK3 - 2822-1275
Speed Control: 2 Turnigy Plush 18 amp
Prop: 2 APC 8 x 4.7 SF
BEC: Turnigy 3A UBEC
Servos: 6 Futaba S3114
Receiver: Orange RX 8 channel (and it uses all 8 of ‘em)
CG: 2.25” behind LE

Flight report:

There is no water rudder, but slow speed taxi is easy with differential throttle mixed with the rudder. On my first flights high speed taxi always ended with a pontoon catching the water and causing the aircraft to spin around, but I soon learned that keeping the nose up with up elevator during taxi fixed that problem. I have not flown from grass yet.

Takeoffs and landings are easy. When empty the wing loading is light and it lifts off at a very slow speed. Control response in flight is good. It does good scalelike loops and rolls.

Instead of separate flaps I used full length ailerons set up as flaperons. While they are effective as flaps, the ailerons produce a lot of adverse yaw when the flaps are down.

The scoop function works well. I occasionally get debris stuck on the scoop, but it hasn’t caused any problems. The tank fills in about 10 seconds, and water can be seen coming out of the overflow holes.

Dumping also works well. My initial concern was of water leaking out of the tank through the hatches, but water leaking in through the hatches is more of an issue. I modified my original hatch design to be hinged at the front which mostly fixed this, and the occasional cycling of the hatch while airborne takes care of the rest. If you intend to do extended flying without using the dump function, the hatch could be temporarily sealed with tape.

I initially thought it was overpowered for a scale plane. Then I lowered the scoop and filled up with water. Now it needs all that power and flies like a pig! But this was planned from the beginning, and I suspect is very prototypical. What do you expect when you put 19 ounces of water in a 28 ounce plane? The contrast keeps it interesting.

Flight times are about 15 minutes with some reserve.

Edit 1/4/15: See post #57 for more flight report info.

Non-prototypical liberties & simplifications:


I traced one of the small-scale 3-views found on the internet into my CAD program with as few mods as possible. Edit 1/4/15: The highest resolution 3-view I have seen is http://www.seawings.co.uk/CL-415Plansgal.htm, but of course I didn’t find this one ‘till I was all done.
Some mods I made are listed here:
I originally had the hatches hinged at the upper edge like the prototype, but I couldn’t get them to close tightly enough and they would force themselves open during fast taxi when the scoop was down. The hatches are now hinged at the front.
I could not cut a hatch with rounded ends and make it hold water, so my hatch is rectangular.
Most 415’s have 4 hatches, but some have only two, so two is OK.
The prototype has two scoops, and they swivel down and forward.
Most of the tail and all control surfaces are flat instead of airfoiled. The “REFERENCE ONLY NACA4417” airfoil section on the plans is a reference if you want to modify it for airfoiled ailerons.
I used flaperons instead of separate flaps to avoid two more servos.
The flaperons required shortening the rear of the nacelle to clear the ailerons in the up position.
The nacelles were squared off a bit.
The front of the nacelles is larger than prototype to accommodate the motors I used.
I left off the little triangular fairing between the outer nacelle side and the wing leading edge.

Still to come:

The time-intensive thing left to do is sanding to final shape and painting.
There was some flutter in the tail at high speed, which I fixed temporarily with a piece of fiberglass strapping tape on each side of the upper vertical tail. I’ll make this more permanent with some CF strips and glue.
The front of my access hatch is now held on with tape, but that will be changed to either a rubber band or magnets.
Most of my battery tray is not used and will probably be removed.
In the scale detail department, I’ll add some wheels in the retracted position (which are not on the plans); and the wing fences, nacelle air scoops, and exhaust outlets have not been added yet.
I plan to build a removable undercarriage to fly off our club field. This will probably be a wire and plywood affair with a nonsteerable nose wheel, held on by tape.

I don’t like posting a build log of a new design until I know it works, but I took plenty of construction photos and will post them here like a build log / construction how-to if there is interest.

The plans are posted below. For part templates you can take your choice of 2 big sheets or 31 letter size sheets. While the letter size is lots of sheets, I managed to get almost all the parts on single sheets, so there are only 12 edges to tape together for the larger parts.

I don’t have any in-flight still pictures yet, but I made a video.

Scott

CL415 (3 min 3 sec)
Last edited by scott swanson; Jan 04, 2015 at 08:17 PM.
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Nov 23, 2014, 06:47 PM
ski bum in training
addictedtoplanes's Avatar
Yesss!!! Finally someone makes a CL415 with usable plans!! (Nibbo's were great, but I couldn't make head or tail of them) And it dumps water!! Any pics of construction?
Nov 23, 2014, 08:35 PM
Registered User
Squall's Avatar
Fantastic plane Scott! Thank you for sharing. I just got a box of MPF and happen to have a couple Suppo 2208's and 18 Amp ESCs available.
Nov 23, 2014, 08:47 PM
Letís eschew obfuscation.
scott swanson's Avatar
Quote:
Originally Posted by addictedtoplanes
Any pics of construction?
Addicted,

I plan on posting annotated construction pictures as a build guide, but keep those cards and letters coming so I know someone is listening.

Thanks for the encouragement,
Scott
Nov 23, 2014, 10:35 PM
TonyS
Very, very nice! Thanks for sharing!!

TonyS
Nov 24, 2014, 12:13 AM
Registered User
Scott awesome looking plane. I love the scoop and dumping function it is awesome! Forgive my nooby question but what do you use for waterproofing thr foam? I would also love to see a build log when your ready to post it. Great work on this plane!
Nov 24, 2014, 02:35 AM
skumgummi dave
Scott:

Beautiful drawings! Very much enjoyed your video. Uber cool!

Dave-
Nov 24, 2014, 04:16 AM
Warbirds Lover
Dreamcatcher's Avatar
Hi !

Thanks a lot for sharing and congratulations for the beautiful bird
Nov 24, 2014, 05:30 AM
Allways the hard way!
georgy's Avatar
Verrry Purdy!
Nov 24, 2014, 06:39 PM
Letís eschew obfuscation.
scott swanson's Avatar
Guys,
Thanks for the positive feedback. As those of you who have done it know, building detailed plans is as much work as building the plane. I am glad they are appreciated.

Fluffybunny,
The foam is waterproof all by itself. If you use waterproof glue, you are good to go. I prefer seaplanes built of foam (vs. balsa & covering) just for that reason.

Some general notes on the build:

This is not a beginner-friendly plane, either for building or flying. So the build notes here are assuming you have foam building experience. If you are less experienced, we are glad to have you read along and ask questions.

I use white Gorilla Glue on all stressed joints. To keep it watertight, make sure the glue bead is continuous. I just let the glue foam out and break off the extra glue after it dries.

The control hinges are Blenderm tape.

Pushrods are .031” stainless steel music wire (P/N 240-2222 from use-enco.com). I use Z-bends on the servo end and Dubro Mini E/Z Connectors on the control horn end. The tail pushrods are Dubro 30” Micro Pushrod System.

I waterproof the pushrod exits with a short piece of heat-shrink tubing shrunk over the pushrod. If it shrinks too tight, it can be loosened by rolling it between two hard surfaces with the pushrod still inside. After the pushrod exit is glued in place, add grease or Vaseline to the pushrod.

The wing servos will be hard to replace later so use good ones. If you need to conserve cash, do it on the servos which are easier to get at.

Step one is print out the parts patterns. Check the ruler printed on some of the sheets to verify that you are printing full size. Note the alignment marks in the corners of the sheets; I use a window as a light table to make these easier to see for taping together the multi-sheet patterns.

Edit 12/24/14: Keep these in mind when totaling your foam quantities: The parts patterns only show one copy of the Wing and Aileron. Also the Wing, the Lower Vertical Tail, and the Pontoon Struts are shown as double thickness, folded at the fold line. And note the top and bottom Wing skins are not the same width.
Last edited by scott swanson; Dec 24, 2014 at 03:02 PM. Reason: clarity
Nov 24, 2014, 09:51 PM
Registered User
Wow! Thanks for sharing this model and plans. It looks like a really gentle flyer and realistic looking
Nov 24, 2014, 11:04 PM
Registered User
numb_thumbs's Avatar
Wow Gorgeous!

I hope you post more pics of the build. I am very interested in seeing how it went/goes together!
Nov 25, 2014, 10:26 AM
Retired CAD guy
birdofplay's Avatar
I've written to Scott re this model.
I have plans arranged on Std Depron sheeting and will be making one
for myself regardless.

On my similarly sized and overbuilt The Twins I used and liked these motors..
http://www.hobbyking.com/hobbyking/s...trSearch=l3010

No problems with hauling the freight :-)
But these may be a bit too much for some.

I have my layout for CNC cutting almost done too.

I've been bored with my The Twins for some time now so THIS will be my next twin ! :-)

C U L8r

Bob
Hoosier Cutout Service
Last edited by birdofplay; Nov 26, 2014 at 07:23 AM.
Nov 25, 2014, 02:11 PM
Letís eschew obfuscation.
scott swanson's Avatar
I built the wing first.

The wing leading edge is made from the fanfold fold. Edit 11/27/14: For those folding a leading edge from flat sheet Depron, experienced guys recommend placing packing tape on the outside of the LE before attempting to bend to prevent cracking.

Sand the inboard end of each wing square and glue the left and right wings together. The curved area of the top skin was scored on the inside of the bend with a fork for the length of the wing. (Thanks Lockey for this tip.) There arenít enough ribs to really hold the wing to shape, so bend the foam till it mostly wants to follow the rib shape.

Sand a taper on the inside of the upper and lower skin at the trailing edge so the TE thickness matches the aileron thickness.

The 8mm CF tube I had for the spar was only 1m long. I extended each end by epoxying a smaller diameter tube into the 8mm tube. I put a short piece of aluminum tubing over the joint as reinforcement, and used paper shims soaked with epoxy to make the fit better. The spar should be short enough that it doesnít get snagged when the wing ends are trimmed to shape. Iím not sure these extensions are necessaryóif someone has experience with a wing spar shorter than the wing, I would be interested in hearing about it. Edit 12/5/14: Nuteman's answer to this question https://www.rcgroups.com/forums/show....php?t=2297316 would suggest that a 1m spar is long enough.

Sand a shallow groove for the spar to locate it and give it more glue area. Glue the spar to the bottom wing skin.

Glue the wing saddle to the bottom of the wing with the wide end toward the front and the rear extending .25Ē past the TE. Sand grooves for 1/8Ē x 5.875Ē CF wing holddown rods for more glue area. Glue the CF rods to the wing saddle with equal overhang on each end; place the fore and aft plywood wing holddowns over the rod ends to maintain the rod spacing while the glue is drying, but you donít want the plywood glued on.

Poke holes through the foam to thread line through, and tie the CF holddown rods to the wing spar with strong line. Otherwise the weight of the plane is hanging by just the glue joint holding the CF rods on. My CF rods are actually tubes, but I filled the ends of the tubes with dowels and chamfered them to make the wing easier to fit into the wing holddowns.

Scott
Last edited by scott swanson; Dec 05, 2014 at 08:24 PM. Reason: add spar length info
Nov 25, 2014, 04:57 PM
Ken's CAD Models
dz1sfb's Avatar
Really great work Scott!

Yeah, the build documentation is as much if not more work than building.

Ken
Latest blog entry: Ken's CAD Models new web site


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