Mighty "Mini" PBY-5A Catalina - WWII Flying Boat

[localfiend]

Well, making these last few parts work has been a pain. A lot more curves going on here than normal. Got lucky up until this point, most of my first drawing for the fuse just worked. Think I've got them figured out now though and the lower hull section shouldn't be too much harder to put together than any of the other more recent FT fuselage designs.


Ok, so here's the other bottom hull piece. Ignore the massive excess paper. I wanted to try something that really didn't work out. The lightening section you cut out of it also doubles as the angle gauge.



Once you have the angle glued it will slide right into here:





You can see how it's kinda ugly on the sides in the back there. I tried using all that excess paper to cover over everything, but it was too crinkly. So I cut most of the excess paper off and just folded over enough to protect the edge of the plate.



Here's the nose plate of the hull. In the future, this will be attached to the fuse rather than a separate piece to cut out. That will be one less seam and should make it easier to assemble. Note the light beveling on the arrowhead looking section. Not really needed but it makes the fit very clean.



Start by gluing down the main back section:



Then go a little at a time until you're done. No need to be sparing with the glue here. You want this to be sealed.



Fold over the excess paper and glue it down. I like to go back over everything with some tape.





I'm starting the drawings for the tail section now.

 

[mrwis@yahoo.com]

Amazing. What are you thinking for the dual motors? What size and prop size? Very interested to see how this comes out.

 

[localfiend]

Amazing. What are you thinking for the dual motors? What size and prop size? Very interested to see how this comes out.

Two F Pack motors (approx 2204 2300kv). 6 inch prop maximum unless you want to get away from scale and move the motors further apart on the wing. I think a 6x3 prop would give the right amount of thrust without the craziness you get from the HQ 6045 style props. We'll see what happens when it's flyable.

 

[localfiend]

After a bunch of testing last night I've decided to abandon this fuselage section. Having the tail section separate was going to introduce strength issues, and I have a way of making the tail section simpler if the two are combined. Most of the parts will remain as they are, though I have changed a couple lines to make things a bit more scale looking.

The old lower hull/fuse will be used for waterproofing tests. I've put on a coat of Water Based Minwax Polycrylic. I'll spray paint over the top of that this evening sometime then see how it does sitting in a bathtub overnight.

 

[localfiend]

Getting started on cutting parts now. Here's what the new lines look like:



Nose shape has been improved. I reduced the angle of the front center ridge as it was too sharp, and added the extended tail sections. The wing mount drawing is there as well, along with a stronger vertical stab/rudder design.

 

[localfiend]

Well, I got distracted with work stuff and only had about an hour and a half to work this evening. Got the new fuse design mostly done though. It went together very smoothly and is starting to look like a PBY now.

New Fuse Section:



Tail:






Curve along the front side of the nose looks much better now, and it's just as easy to assemble as it was before. I think I've captured most of main lines of the plane, it's very scale. At least for the bottom.






I think this tail design will be quite strong with the angled bottom plate. I'm considering lengthening the bottom section of the vertical stabilizer up further towards the front of the plane. That will make it act like a spar. Might add a couple doublers to either side of the stab as well. Or maybe do some sort of box spar. If I do that, It will be very tough to hurt the tail.

I don't think weight is going to be an issue. Even with all the hot glue I'm using to seal stuff, that entire assembly pictured above only weighs 61 grams!

 

[localfiend]

Paint is dried on the old test fuse section:





I don't think there will be any problems. Should be quite waterproof after a coat of polycrylic and a coat of paint.

Any floatplane experts out there?

I'm wondering about a few things. Can a float plane be too light to be stable on water? Any thoughts on wingtip float heights? Are the wingtip floats just supposed to sorta bounce off the surface of the water if your plane tips to either side? I'd imagine the lighter the plane, the easier it is to catch an edge.

 

[willsonman]

Well, Ideally you should have the aircraft sit at the same height IN the water for better water handling. Not gonna happen here unless you do like some... purposefully put holes in it and have a sump pump to maintain the correct ride line in the water. I can't make this stuff up people... I've seen it done.

The long and short of it is that the tip floats provide stability on the water until you get enough speed to get up on the step of the fuselage. Once there, the tips should not be touching the water... thus the need for correct ride height in the water. Scale water stuff is tricky business.

 

[localfiend]

Well, Ideally you should have the aircraft sit at the same height IN the water for better water handling. Not gonna happen here unless you do like some... purposefully put holes in it and have a sump pump to maintain the correct ride line in the water. I can't make this stuff up people... I've seen it done.

The long and short of it is that the tip floats provide stability on the water until you get enough speed to get up on the step of the fuselage. Once there, the tips should not be touching the water... thus the need for correct ride height in the water. Scale water stuff is tricky business.

Heh. I think i've got some fish tank pumps that might work.... Nah, too complicated for something this small I think. When I first started drawing up the plans for this I started with a 60" wingspan. Maybe after this version gets done I'll go back to huge and can do some more scale stuff.

Ride height is what I was worried about, no way this thing is going to sink into the water as far as a real Catalina.

The current fuse design does still have a steeper main point than scale, and I'm hoping that may work in my favor. That ridge at the least will be deeper than with a flatter bottom and should hopefully add some stability. Think I'm going to go do some reading on boat hull design.

Right now, I'm thinking about just leaving the wingtip float heights at scale. That will leave them further up above the water since my version won't sink as much, but I think that's a good thing. I'd imagine it'd be really easy to spin out if one of those tips hits the water on something so light.

Another thought is that it might be a good idea to add weight for water flying. Maybe just stick another 2200mAh battery in the hatch. We'll see about that after I get the wing attached and start working on CG and electronics placement.

 

[DumbThumbsRC]

Wow. You are doing an amazing job. Looking forward to seeing this one finished and flying.

 

[areford]

This is really looking great LF! I am eagerly awaiting the future posts and i like the idea of a larger version as well!

 

[Elexo]

I need to stop finding awesome planes, I'm running out of room and cash! Maybe some plans once it flies? Subscribed

 

[localfiend]

This is really looking great LF! I am eagerly awaiting the future posts and i like the idea of a larger version as well!

Yeah, I think a big version would be pretty cool. Something built to take 2 C pack motors and the FT simple firewalls would be pretty awesome. But, that's quite a ways off. Got to make sure this one works well first.

I need to stop finding awesome planes, I'm running out of room and cash! Maybe some plans once it flies? Subscribed

I will be releasing plans like I do for all my designs. I constantly update my plans as I build, just part of my process. When I have a plane flying the plans are generally pretty much ready to go.




I seem to have caught the bug that's going around, and have been shivering to badly to hold a razor blade. Did finish the testing on the old fuselage though. Didn't go quite as I hoped.

I stuck the fuse into the bathtub, an hour later everything was still good so I left it. I took a nap and didn't check it for another 5 hours. This was the result:

Apparently, one coat of minwax and one coat of paint is not enough.



Probably pinhole leaks in the minwax and paint covering. All the paper eventually absorbed water. On the bright side, it didn't leak. Kept the water out like a charm, just did bad things to the paper.

The paper got wet all the way to the top. Comes right off though.





So. I think I'm going to abandon the keeping the paper on for a plane designed for water use. I'll pull off the paper off both sides of a sheet of foambard (it's incredibly easy to remove, takes about 10 seconds per side), then coat one side of the foamboard with packing tape. This will give excellent abrasion resistance if you want to do belly landings as well, and should be perfectly waterproof.

 

[Bonards]

So. I think I'm going to abandon the keeping the paper on for a plane designed for water use. I'll pull off the paper off both sides of a sheet of foambard (it's incredibly easy to remove, takes about 10 seconds per side), then coat one side of the foamboard with packing tape. This will give excellent abrasion resistance if you want to do belly landings as well, and should be perfectly waterproof.

I would tell you that, as I already sad, here in Brazil is hard to find this foam board with papers only the simple foam foam-board(does this exist?). So we build the plane and cover with tape, I built a few years ago a SEA-BB, its nice plane for beginners and simple to built.

I have one question to you, what's the program that you use to design the plans and save as PDF? I have a lots of ideas but I just have the Google SketchUp to desing and it's not nice to do those curved parts in this program.

 

[localfiend]

I would tell you that, as I already sad, here in Brazil is hard to find this foam board with papers only the simple foam foam-board(does this exist?). So we build the plane and cover with tape, I built a few years ago a SEA-BB, its nice plane for beginners and simple to built.

I have one question to you, what's the program that you use to design the plans and save as PDF? I have a lots of ideas but I just have the Google SketchUp to desing and it's not nice to do those curved parts in this program.

Yeah, I've had really good luck with packing tape covering. Just had that fuse sitting there, and thought I'd test out the paint and minwax to see what would happen.

I use DoubleCad XT for drawing up and printing my plans. It's free and easy to use. I tried to use SketchUp, but it drove me crazy.

I just posted a thread in the Plans section. I'll be going over how I draw up and print my designs. I plan to make some more videos, but that will have to wait until my voice returns. For now, you can download the template I've posted up and try it out.

http://forum.flitetest.com/showthread.php?25514-FT-Style-CAD-Templates

 

[Bonards]

Yeah, I've had really good luck with packing tape covering. Just had that fuse sitting there, and thought I'd test out the paint and minwax to see what would happen.

I use DoubleCad XT for drawing up and printing my plans. It's free and easy to use. I tried to use SketchUp, but it drove me crazy.

I just posted a thread in the Plans section. I'll be going over how I draw up and print my designs. I plan to make some more videos, but that will have to wait until my voice returns. For now, you can download the template I've posted up and try it out.

http://forum.flitetest.com/showthread.php?25514-FT-Style-CAD-Templates

Nice Licalfiend! I was looking for a program like this, free and easy to use! I'll download the program and try to use it with my experience, as a friend of mine says "experience is everything you learn without manuals!".

I can't wait to see this catalina ready, it's one of my favorite hidroplane.

 

[localfiend]

Still sick, this is a nasty bug, but feeling a bit better today. Decided to get back to work if only to move around a little.

Working on the wing tower now. I think this will be strong enough to support the wing without the side supports, which will allow for a removable wing for those who might want that option.









I still plan on having the 4 external wing supports. They're needed for looks, and will add even more strength if you're going to increase weight or speed. I'm thinking now that 2 F pack motors may even be overkill, and that 2 A pack motors will pull this through the air just fine.

I'm also working on formers for the upper decking. I think for this build I may make 3 different sets of formers available. Since this is going to be all terrain, you'll have your choice of materials for the upper decking.

Posterboard for a build that will never see water, and then formers for 3mm hobbyking foam and 5mm DTF. I think both foam types will work well as upper decking with paper removed from both sides. Once the decking is installed, if you used foam, give it a coat of polycrylic and paint.

 

[dgrigor02]

If you haven't done so already, check out episode 8 - "This One Time At Build Camp" by FliteTest Community Cast.

 

[localfiend]

If you haven't done so already, check out episode 8 - "This One Time At Build Camp" by FliteTest Community Cast.

Uhoh. People with access to microphones know who I am. Time to abandon ship!

I haven't ever listened to them before. Not a lot of downtime when I'm not focused entirely on something else. Sounds like they have some good ideas though. The google meeting stuff is powerful, and using it to answer build questions could be be pretty cool.

 

[m00ndancer]

If you do it as a hangout on Air it will be saved as a youtube video, for later viewing. If you want some suggestion or want to test it out just pm me Localfiend.