FTFC20 - Vought OS2U-3 "Kingfisher" by FoamyDM

[FoamyDM]

Inspiration:
During Family Day Trip to Wilmington, NC with my Mother, Step-Father and Sons, we stopped in to U.S.S. North Carolina. a WWII Battleship. Something I had passed EVERY time I went to Wilmington over the years living in NC. As the morning was cloudy and a bit rainy, it was a perfect way to spend a morning. (with the snake museum - Large collection of Crazy-deadly snakes) during the wet time to follow. I came around the rear gun turret to find to my immense surprise and delight a PLANE!

As I learned all about this craft, I learned it was the Vought OS2U - Kingfisher. A trainer-looking water craft sitting on the end of the rear deck.
(these are personal pictures from the trip.)
This whole thing fascinated me. I needed to know the How's and Why's of it!

Why: It slices, it dices, it juliennes fries
I found out (if you read the plaques) the craft was used for many roles during service. It was used for the mail, communications, AA artillery gun practice (see left of the left wing in the first pic), and most importantly Scouting missions, to see what they were coming onto. There is also a whole discussion on the landing techniques for the craft. the plane would signal in and the battleship would build a wake-runway in the water then swing around to the port for retrieval through a special skid and crane.

Above- Using the retrieval crane to mount the plane onto the Launch catapult.

How: Up, up and away
So now we understand how critical the Kingfisher's role was on the Battleships, The biggest challenge they faced was to safely launch this without a runway.
The short is - they used a powder actuated catapult. The pilots would angle into the wind, rev up the engine. and on "go", would cause a powder charge to explode and send the plane off the short length over the side. 0-70 mph (0-112 kph) in 68 feet (~20m). WOW - So Cool!

After that trip I was looking around, and I found a Sim Model (RF 7.5) and tried it. It Flew SO light and floaty. Just a relaxing joy to buzz around in on the sim. Also fun to practice water landings with! Since that point I've been wanting to design this up, build and fly it.

Historical Plans:

Real Pictures:


Project Goals:

1. Based on some talk here about building a 1:40th scale aircraft Carrier to land and launch planes from, I wanted to build a ~13.5" wingspan, yard-sized bird that would fit on that scale Battleship.
2. I wanted to double it to 30" for a C-pack size, to enjoy the fun I had in the sim in real life.
3. Build a scale sized powder actuated Launch Catapult!

Real - Life Plane Operational Parameters:

General characteristics​

• Crew: Two, pilot and observer
• Length: 33 ft 10 in (10.31 m)
• Wingspan: 35 ft 11 in (10.95 m)
• Height: 15 ft 1.5 in (4.61 m)
• Wing area: 262 ft² (24 m²)
• Empty weight: 4,123 lb (1,870 kg)
• Max. takeoff weight: 6,000 lb (2,721 kg)
• Powerplant: 1 × Pratt & Whitney R-985-AN-2 radial engine, 450 hp (336 kW)

Performance​

• Maximum speed: 164 mph (264 km/h)
• Range: 805 mi (1,296 km)
• Service ceiling: 13,000 ft (3,960 m)

Armament​

• Guns: 2 × .30 in (7.62 mm) M1919 Browning machine guns ( one on flexible mount for observer )
• Bombs: 650 lb (295 kg) of bombs

R/C Operational Parameters:

A-Pack	C/B-Pack
Length: 13.5 in (34.2 cm) Wingspan: 14.4" (36.6 cm) Height: 6 in (16 cm) Wing area: 44 in² (284 cm²) Base weight: 5.3 oz. (150g) Est. AUW: 7oz. (190g) Motor: 1806, 2300kv / 1104, 7500kv (18g/ 6g) Battery: 550 mAh 2S, 7.4V (36g) Propeller: 3023x3 (5g) ESC: 12a / 6A (9g / 5.5g) Servos: - 2-4 5g (20g)	Length: 27.5 in (68 cm) Wingspan: 30" (70 cm) Height: 12 in (32 cm) Wing area: 190 in² (12,258 cm²) Base weight: 7 oz. (200g) Est. AUW: 9.17 oz. (260g) Motor: 2822/09, 900kv (34g) Battery: 1500 mAh 3S, 11.1V (80g) Propeller: 8x4.7 (5g) ESC: 30A (12g) Servos: - 4-6 9g (36-54g)

A-Pack Plans and Build

Alpha Build Plans

Alpha Build without electronics:

C-Pack Beta Plans and Build

Plane Resource link: https://forum.flitetest.com/index.php?resources/vought-os2u-kingfisher-by-foamydm.109/
Build Log: (more details in the post below)

when you're done she'll look like this: (current picture is a progress picture.)

FTFC20 - Classic to Modern by FoamyDM (Plan conversion)


Come and Build one with me and let me know how it goes, as feedback is always a gift!

 

[FoamyDM]

A number of Refinements have yet to be included.
Side note - 5g servos are much more expensive (2.5x) and thereby I have not stocked up. in my mind this is 3- 5g servos, setup like the baby bloody baron.
The plans don't include the Cowl (which they will)
I also have not left holes for the servos, the electronics hatch nor a receiver.
Also it has clearance for a 3" prop or less. I think the gremlin quad 1104 motors or 1106 motors might be best
it doesn't include the rudder on the float either (I plan to make from Gift Card plastic one as part)
I will update as I go

 

[rockyboy]

Something about the front end with the little hole in the windshield makes me think of a cyclops sticking it's tongue out

I know people often have challenges getting planes this small to fly well using DTFB - it tends to be a bit heavy and non-aerodynamic at this scale. I've only had one success but we didn't have 1104 and 1006 quad motors back then - those pack a lot more power at lower weight than what I could find cheaply three years ago

One other thought when working at this scale is to round off the square edge of the tail surfaces so they operate with less turbulence - sanding or squishing with a hot iron could help there.

 

[Arcfyre]

I've always wanted an RC Kingfisher. I'm big on float planes in general, and I've always wanted to try my hand at the single float type. The 13.5" size is a little small for me, as most of my models are 36" or larger. Once you scale it up I'd be happy to build an alpha model. Following.

 

[FoamyDM]

This project has been on hold until i could electrify it. Thanks for the Tip @rockyboy for working with this scale. I planned to skewer the front of the empennage.

I fully intend on scaling this up @Arcfyre.
For the Traditional Park flyer scale, ultimately I was thinking C-pack, with a 10" slow fly prop. keep watching, the scale up will be coming.
As for now, this project is limited to Stupid small.

guess what came in?

come on... Guess.


That's right, 20 - 3.7g micro SERVOS! Micro projects ahoy! I found them for ~$2 (they may end up being worth more with duds. but it means I can experiment.)

 

[FoamyDM]

Right now I enter this into the FTFC contest as a conversion of this 15" plan. <--- @rockyboy

Would anyone like to see this in a 1/12 scale (36" wingspan) or 1/6 (72" Wingspan) scale version? This was always the plan but I see a challenge that this may fit into the FTFC20 - Classic to Modern Challenge. I have wanted to set this to a bigger scale. so I will enter the 36" as a Version of THIS PLAN.

 

[FoamyDM]

come on... Guess.

That's right, 20 - 3.7g micro SERVOS! Micro projects ahoy! I found them for ~$2 (they may end up being worth more with duds. but it means I can experiment.)

Sadly the servo monster came and ate them or buried them in the back yard for later as I couldn't find them when I looked for them.

next shipment and organized shop coming.

 

[FoamyDM]

I started cutting the c/b pack plans.

As I cut this out, I realized the plans need a small amount of work so they line up right. Biggest change are the wing floats.

 

[Qwenther]

This thing looks like heaps of fun. I just might have to build one when you get the beta out.

I noticed on your alpha build you have a cross styled BBQ skewer setup holding the center pontoon. Would double layering some foam over some skewers with a "C" fold provide the needed reinforcement and extra gluing surface making the joint stronger and giving it the scale look of the real bird?

 

[FoamyDM]

according to the Sims, this will fly amazing. I hope to get some building done this weekend.

 

[FoamyDM]

This thing looks like heaps of fun. I just might have to build one when you get the beta out.

I noticed on your alpha build you have a cross styled BBQ skewer setup holding the center pontoon. Would double layering some foam over some skewers with a "C" fold provide the needed reinforcement and extra gluing surface making the joint stronger and giving it the scale look of the real bird?

I'm sure it would. I will be looking at a number of methods. What you described is looking like my favorite (for scale's sake.) But at days end, it needs to be able to take off and land.

I made decent progress Last night. I had to take after-the-fact pictures. I forgot to, while I was embroiled in it.

Put together the wings, and fuselage. and worked at mating them. I had a small amount of carving to fit the wings better. I would like to say that it is on purpose, but that would be to big a fib.

Some details of the tail section. I added alignment tabs (not Visible) to the inside walls of the rear sections. It fit well. a notch or
Empenage - a shoe horn was required. the H. Stab was too wide to fit through the designed slot. I tried my hand at butchering... it's not my chosen profession, and it shows.

Wingtip pontoons: not the smeared glue used as a filler, and waterproofing agent.

Main Pontoon - Missing the step riser piece. I need to add it to the plans.

Canopy build. Some trimming was required for good fitment. I think a Plastic former might help these keep their shape better.
front canopy and the inside. note that not all the paper was removed. There were a few adjustments here too.

Back Canopy. the former would REALLY help here. note the beveled base of both items. I would like this to be two parts and slide. (on a servo).

I missed an all-together shot this morning. but here is a nice 3/4 view shot.

*Post edited 10/10 to add descriptions and for consumption ease*

 

[Qwenther]

That's some amazing progress, I like where this is headed. Keep it up, cause I just added this to my future projects list. And the pontoon mount idea should work, I've tried the concept myself on one my birds and it worked.

 

[FoamyDM]

Based on this modest success I have adjusted the plans to match my notes, and will added it to the first post information

Plan Post Link

 

[FoamyDM]

Canopy fits well, but I will put something to keep it in form.

Mighty mini and the full size one.

I think I like the pontoons for the mighty mini version best, but the plane itself is C-pack construction. Hands down.

Now, time to make it fly.

 

[Qwenther]

This is amazing. yep I really wanna build one, totally added to my project list now. It's beautiful. I am curious, are your gonna waterproof it for launching it off a lake or river?

 

[FoamyDM]

Yes, When I'm done I will figure out a way.

I have this Foolish vision, of Making a 8' long Battleship - and add two micro mini catapult mechanisms on the back with a model of it. I thought... what if the main guns or the AA gunner stations were setup with Air-soft mechanisms and there was an FPV setup and firing controls in each. At events you have non-pilots at events trying to take out pilots who try to "sink" the battleship to simulate a sea battle. the main guns are a potato launcher and they shoot across the field at a Box - or boxes each has a "charge" of powder so when hit by a potato they "explode".

Sadly, my local group just wants to fly. I think i need to find my local Maker group for the rest of my ideas...

anyway... you have the idea. a way to involve the

 

[Qwenther]

Yes, When I'm done I will figure out a way.

I have this Foolish vision, of Making a 8' long Battleship - and add two micro mini catapult mechanisms on the back with a model of it. I thought... what if the main guns or the AA gunner stations were setup with Air-soft mechanisms and there was an FPV setup and firing controls in each. At events you have non-pilots at events trying to take out pilots who try to "sink" the battleship to simulate a sea battle. the main guns are a potato launcher and they shoot across the field at a Box - or boxes each has a "charge" of powder so when hit by a potato they "explode".

Sadly, my local group just wants to fly. I think i need to find my local Maker group for the rest of my ideas...

anyway... you have the idea. a way to involve the

This sounds like a crazy dream I had once of making a 14' aircraft carrier with a similar setup for both launch and retrieval. But instead of BB pellets and co2 I was gonna use the currently in development laser tag system for reduced damage. I also wanted to use planes like the mini corsair and somebody made some zero fighters, also with laser tag(mini version) and ultra-micro retracts(If they existed in a way I could get my hands on them). And yeah, This kind of thing would get the community involved even non-pilots. This would be whole heaps o fun.

 

[FoamyDM]

I eeked out a little bit of time last night to work on this project.
Not of it was building, aligning, and lengthening the vertical posts along the centerline of the pontoon, and attaching them securely

I hope to be done tonight with the build.

 

[K3V0]

This is a cool journey! I hadn’t heard of the plane before, thanks for sharing its history. I love that you just happened upon it. Explosive catapults! Destroyer wake runways! The ingenuity demonstrated in aviation history is constantly impressive, it’s one of the few subjects that makes me feel like a kid again😄

 

[FoamyDM]

This is a cool journey! I hadn’t heard of the plane before, thanks for sharing its history. I love that you just happened upon it. Explosive catapults! Destroyer wake runways! The ingenuity demonstrated in aviation history is constantly impressive, it’s one of the few subjects that makes me feel like a kid again😄

I'm with you.
It brings back that sense of wonder an awe we had far more often as a child. (possibly why I love this hobby's front edge and I read breaking tech, and Whitepapers, SF often thinking to myself, "we figured out WHAT!?")

At first, for me, it was just - build a plane. I didn't care about the plane itself, just desired to build and fly it. And then I took part in one of @rockyboy FliteTest Forum Challenges (FTFC), who's major component was to bring forth the history of the craft you were building, beyond, where's the 3-view. Through this I really started to Learn about our aviation history. and truly build a Catalog of Aircraft. Getting an opportunity to visit the Wright Brother's Monument to flight a Kill Devil Hills, NC was a good start, and meant more armed with the basics I learned through FT and my own aviation journey to that point.
It seems that every time I think, "That's any interesting looking plane, let me build that!" that turns out to be the least interesting part of the model making journey. Digging into and through the histories brings the memories and details of the plane to life. often times helps me understand why this plane is the way it is, and the hardships the designers had to overcome to make that craft a success (or not).
of course seeing this plane in person, in (for me) the most unlikely and surprising locations, set among it's function, and neighbored by the long list of enlisted soldiers who payed the ultimate price in the relatively short journey, made a larger impact with this craft than seeing a picture or article of a built model of it.

The History rabbit hole, makes all the difference.