I met a customer at work last week who needs some custom welding done. He owns a C-47 and wants to convert it to a float plane. Boss wants me to be the lead welder on the project and design and fabricate the floats. Here’s a few pics of what he wants to do.
John (the customer) is down in Texas so I’ll be using my modeling skils to build these floats. I’m going to have to use known dimensions on the C-47 to figure out what size the floats are. We figure they’re made out of aluminum, so it’s going to be a lot of TIG welding to get this project to completion. Then we’ll ship the floats to Texas and they’ll be installed on the plane.
If all goes well on the C-47 Johns next project is the restoration of a B-17 that will also be a float plane. In early 1942 Boeing equipped several B-17’s with floats as a trial for the US Navy to have strategic bombing capability. It looked good on paper but didn’t work quite right so the project was cancelled.
Just as I was getting bored with this job and looking for another one a cool project falls in my lap. Fun!
Thought you aircraft modelers might enjoy these pics.
I gotta admit, never new they did that to a plane that large that wasnt designed for it. Pretty cool.
I also must admit, I’m curious to see how a B-17 with floats would look. But I’d MUCH rather see a model of one built as opposed to a real B-17. I’d really hate to see an airworthy B-17 airframe wasted in a crash (not to mention any loss of life) considering how few of them exist. To each his own, especially when there is deep pockets but I’m not for possibly wasting a valuable piece of history on either of these aircraft.
I may have to look around for sources a bit, but I think that the float-equipped C-47s were the largest float-planes ever built. The only other plane that could fit that title would be the Zeppelin Staakens built in WWI that had floats. When the term “largest” was used, it may have been by weight, though, which is what gave the C-47s the edge.
Neat photos Dew. But there is a really really huge problem,. The successful seaplanes, which is what this really is since each float is bigger than a Curtiss Seagull or a Vought Kingfisher, have high wings, and even then often have their engines mounted higher still. I’ve wracked my brain and cannot find a single example of a large low winged monoplane seaplane design, with multiple engines, that worked.
Something like a Cessna thats been converted to a floatplane, or an Otter, has an engine that is relatively high off of the water compared to the length of takeoff, and can survive a little of the wet stuff. A C-47 or God help us a B-17 has oil cooler intakes under the cowl, leading edge radiators etc. that are going to get drenched on a long takeoff. And obviously both have to have their COG shifted forward, or at least compensated for so that they sit level on the water. And the Fortress has those superchargers under the nacelle, oh my.
The B-17 is a few years down the road at least. The one he has hasn’t flown since 1951 and is a total project. He found it at an airplane salvage yard in southern California. For the last 2 years he’s been researching the project and doing the FAA red tape dance to find out what’s required in getting it recertified when the time comes. John said it would cost roughly $3.5 million to restore the aircraft to a flyable B-17 floatplane with U.S. Navy markings.
The C-47 is going to be redone in U.S. Army markings and is also getting a complete restoration. Budget on that is $1.8 million.
Figure our shop will have 1,500 hours at least in (I think it may run much higher than that) fabricating the floats from scratch. Our fabricating rate is $135/hour plus the cost of materials.
It must be nice to be a history buff with money to spare. He also has a P-38 and P-51 in the final stages of restoration. Farther down the road he also wants to do a PBY Catalina.
It’s like modeling I guess. Except Johns stash is bigger and much more expensive.
I’m excited about doing my own little part. Harry (my boss) never turns down work. Which is funny considering we mainly work on single engine general aviation. Nothing commercial or very big. This is going to push our capabilities to the max. If it’s cool with John I can post pics of the floats as I build them. Have to ask though, it’s his dime and he may not want pics of his birds all over the internet. He does have some on his MySpace page and I will ask if I can link to it here for your viewing pleasure.
I don’t usually throw my weight around, but trust me, this is not even a remotely good idea! Given my experience in the industry and my education, I wouldn’t touch this problem with a 10’ pole on a real warbird. If it was on a bird that was a dime a dozen, maybe…but nothing old. No way. Forgetting for a moment all the layout issues that others have mentioned, you have real issues with the hydrodynamics of the step on that big of a float. Unless you have access to whatever plans Boeing and Douglas drew up and used for their respective midwar wackjob ideas, don’t even think about trying to reverse engineer one from pictures. Especially if you expect it to work and not just be for static display.
However, there have been examples of large, multi-engined seaplanes with a low-mounted monoplane:
The Cant Z.511:
I’d love to find and build the O’Neil vacuform kit.
The Ha 139
One day, I’ll tackle the Mach 2 kit of this baby…
We got a bunch of scale drawings of a C-47 on Thursday. I’ve spent the last 5 days trying to draw out what I see in the pictures on the drawings. It’s tough but I’m getting closer. Now I’m at the stage where I’m tweaking it and it’s almost right. By Wednesday I should have a decent set of scale drawings that we can FedEx to John for his approval. I may have 50 hours in this before I even cut one piece of aluminum or stitch one weld. The mechanics have been scratching their heads over the retractable landing gear. We have technical manuals scattered all over the shop too. I’m taking a few aeronautics classes this semester so I can ask my professors to take a look at the figures. It’s definetely a challenge for our little shop. We think we’re working on a big plane when a Cessna Caravan shows up! Mike has some experiece working on amphibs, about 15 years ago in Alaska!
Harry, bless his heart, just can’t say no to work. It would be nice if he wasn’t so enthusiastic. Were skilled mechanics and fabricators, but we’re not exactly “WW2 airframe specialists”. Heck the only thing from that era I’ve seen come through our shop was a P51 landing gear strut. Anyway. So it’s up to the welding department (me, myself, and I) and the mechanics (Mike and Fred) to deliver. At least Fred can weld a little, that will be nice when it comes time to build the frame and skin it. Fred, Mike and I already said Harry can have the job of crating and shipping the damn things.
There’s probably a reason John called dozens of shops before Harry said “Sure! No Problem!”.
Have some faith Herr Hammer. If she crashes it won’t be because of our floats! I’m definetely doing my homework. It’s very fortuitous that I’m taking some aeronautics classes this semester.
One thing that does puzzle me is that I figure these floats will add roughly 2,145lbs to the weight of the C-47. Thats a very rough figure. I haven’t factored in the aerodynamic drag but it should be significant. I’ll have to have a professor or grad student go over the plans and help me figure it out. So I’m curious as to how much cargo/passengers it would be able to carry in this configuration. I’d suspect not much. They will also seriously affect top speed, I imagine.
I’ll put it in context… Back when the CAF discovered the B-29, “Fifi” at China Lake Naval Weapons Test Center, the restoration crew spent about 4 months in the desert getting her ready to fly out of there. The Navy wouldn’t allow any test flights though, so when they they did the first test flight, it was going to one way, non-stop, all the way to to Harlingen, Texas. During the ensuing week of the flight, “Fifi” (not her name at the time) was crammed with every spare B-29 part the crew could fit into her, and the flight crew boarded and fired her up. While they were doing that, the Navy sent a crew out to film it. The rest was history. Fifi took off, circled the range once, and headed East to Texas.
Some weeks later, the 16mm film the Navy shot that day was presented to CAF Colonel Lloyd Nolan, the Founder of the CAF, in Harlingen. After watching it with the Navy guys, Lloyd remarked that he didn’t know that the Navy had wanted to film the take-off. The Navy Officer replied, “We didn’t come out there to film the take-off, we came out there to film the crash…”
[:D]
I always liked that story, and made a habit of retelling it to the folks that we took on-board “Fifi” during pre-airshow (I was on her Flight Crew for two years, Scanner/APU Operator) media flights…
That’s one heck of a project! Good luck on it, and please do have your plans and calculations reviewed by the experts: not just aeronautical engineers, but material-strength engineers too. The latter may actually offer the most important and relevant input.
A quick google serach turned up this page about the early military trials. More recently, it says that there has been a C-47 floatplane making flights since 1990.
A few of the highlights from this link:
… 1-ton floats, (the largest floats ever built)
… Each float also had a 325 gallon fuel tank.
… The floats had retractable wheels and could land on water, snow or land.
… Pilots found the C-47C difficult to launch in rough water, and performed like a pogo stick when landing on anything but a mirror smooth body of water
My Thought exactly!!! As a Landscape architect I don’t do anything without consulting the apporpriate professionals and most importantly the structural engineer. I wouldn’t trust this to professors or grad students, only certified registered professionals. Of particular importance is the lives of the people who will be flying in this thing. That is not a responsibility to be taken lightly. PLEASE, have your plans reviewed and signed off by a registered engineer. Your employer will thank you for doing so if this thing does crash and somebody is looking for someone to sue! Sorry for the rant but this is not to be taken lightly.
There’s been a few multi-engined low-wing monoplanes that have been successfully adapted for use on floats - the example that leaps out at me is the Beech 18. The engines aren’t any lower to the water than they would be on, say, a single-engine Cessna, and the carb intakes are still tucked inside the lower part of the cowl. I’ve also seen Piper Azteks on floats.
On the C-47 the struts betweent the plane and the floats are going to have to be quite large, so engine clearance shouldn’t be a problem - they’ll end up sitting about as high off the water as they would with the bird on her wheels, I bet.
I wonder if this owner contacted Wipline and/or Edo (makers of aircraft floats) and they told him to take a hike.
My question is - Why? Why spend $1.8M converting a C-47 for use on the water, when a well-outfitted, airworthy Grumman Albatross goes for $400-600K? I would leave that grand old lady on her wheels, where she’s comfortable. For what this guy’s spending, you could buy both a C-47 and an Albatross, and still have plenty left over for restoration and upkeep on both aircraft.
The insurance on that thing is going to be rediculous, too. I really don’t see the point. [%-)]
Great idea **MD…**and I admire your guts…so many variables in question. Can you guys build a model for wind tunnel testing? You can’t afford to guess where the floats and tail stabes might be located.
…and then there is the idea of your great pics…none of which were in the water.
Years ago I remember one of those puppys flying in for the local airshow (back when Manchester airport…now Manchester-Boston regional…actually HOSTED airshows) and thought it was pretty cool. But then I saw her flying. Boy, talk about slower than a dead snail stuck in glue! [:D] I think hot air baloons were passing it [;)]
I spent the afternoon wandering around the airport. There are 3 amphibs here. Got some ideas, took some pictures, made a few stencils. I think I can pull this off.
We don’t have the resources/ability to build a scale model and wind tunnel test it. So we’re going to use science, math, and fabricating sense to build it.
The intitial plans go off to John tomorrow. Basically I’m going to use aluminum tube (DOM) to build a framework and then skin it. I’m thinking 12 gauge aluminum on the bottom since that has to take the impact of the plane hitting the water. The sides I’ll likely skin in 16 gauge aluminum and the top will be 22 gauge. This should keep the weight down to a manageable level. I hope. For mounts for hydraulics I will likely use 1/2" aluminum plate triangulated into the frame.
Right now the big debate is rivets versus TIG’ing the skins. Fred says TIG welding wasn’t invented until the 1960’s so the skins on the floats would have been riveted or gas welded. I’d like to TIG everything possible because I know it will be stronger and more watertight than riveting. Even though it won’t be period correct. My contention is it will be safer, stronger, and lighter than riveting.
The rudders are another source of debate. I think the best way to do the rudders on the floats would be an electric over hydraulic system. Have a hydraulic system in each float electrically controlled from the cockpit. Fred wants to tie it in to the planes hydraulic system.
The landing gear hydraulics are a real ball buster. I’m not an aircraft mechanic so I’ll have to leve that up to Mike and Fred. Apparently to get the front struts to swing out and down requires custom pieces. Mike thinks he can modify something off a Piper to work but isn’t sure it can take the weight. If not we’ll be spending some serious time in the machine shop.
It’s not a walk in the park, but I think we’ll be able to work through it. Thanks for posting that link. I had no idea one of these aircraft was still around. I must try to look at it personally.
