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

Skillless

New member
I positioned the tubes for the pushrods so that they can't fold further inwards. You can see the white pushrod is completely gone and in the orange tube when lowered. Theoretically they could fold outwards when you apply a great enough force on them. I tried to do this on purpose an they seem to be pretty sturdy. It's possible to wiggle them around a little because there's a bit of slack in the servo linkages but I think this may even be helpful to prevent serious damge in case of a harder impact.

To be clear: I have no idea how well they will hold up. I think I will see as soon as I am ready to maiden it. I will let you know.


Oh by the way, I only plan on using them when landing on water. On grass I will try bellylanding it without the floats.

As to the maiden: Do you think it's a good idea to maiden it of the water or should I try handlaunching it first?
 

localfiend

I like 3D printers...
Mentor
I positioned the tubes for the pushrods so that they can't fold further inwards. You can see the white pushrod is completely gone and in the orange tube when lowered. Theoretically they could fold outwards when you apply a great enough force on them. I tried to do this on purpose an they seem to be pretty sturdy. It's possible to wiggle them around a little because there's a bit of slack in the servo linkages but I think this may even be helpful to prevent serious damge in case of a harder impact.

To be clear: I have no idea how well they will hold up. I think I will see as soon as I am ready to maiden it. I will let you know.


Oh by the way, I only plan on using them when landing on water. On grass I will try bellylanding it without the floats.

As to the maiden: Do you think it's a good idea to maiden it of the water or should I try handlaunching it first?

Guess we'll have to see if you run into any servo issues, as it could strip out without being locked from moving in both directions. I've been playing with a couple different locking methods that could be 3d printed but nothing is close. Your way is simple, and a stripped servo isn't a big deal when you've got an access hatch.

You'll be able to belly land without them no problem. You can even take off but it's a bit trickier. Having the floats for ground takeoffs eliminates the need to use ailerons to keep level.

As for the maiden, I've done quite a few maidens off the water, but I'm a bit crazy. :D The PBY is really easy to hand launch though, so that might be a good idea for the first attempt. Water takeoffs for a PBY are a bit tricky with just about every model I've found on the internet. Not to mention the full size ones. :D I'm excited to see how the new hull manages water. Hopefully it's self stabilizing and the wingtip floats will just help in the turns.
 

Skillless

New member
Okay, last weekend I had the chance to get flying twice and, first things first, this plane is amazing. It flies nice and easy and it looks absolutely stunning in the air. Concerning my float mechanism, there are a few things I learned and I had to improve.

On my first attempts on starting out of the water, I had a lot of water splashing into the props and also I perfomed a lot of funny pirouettes, very much like in one of the first videos localfiend uploaded. I took me a bit but I was able to get it off the water anyway. Then I "landished" quite hard and destroyed one of the floats. Turns out the weekspot was the hinges glued to the paper, which delaminated from the foam when wet. Back home I tried some tweaks, which happen do work perfectly.

First I adjusted the CG. From my new won experience it is absolutely critical for nice takeoffs to have the CG PERFECTLY centered. Mine was off just a tiny bit to the right, not enough to feel it in the air but the difference on the water was huge. Next I reinforced the glue points for the hinges with a bit of wood, which also made the floats a tiny bit longer.
When the plane now sits on one of them in the water, the other float ALMOST touches the surface but its still possible to see if it sits on the left or right float at the moment.

IMG_20170315_164313162a.jpg

The last thing I did, was makeing some splashguards so the bow wave doesn't hit the props anymore. They are a bit bigger then scale, but I think they don't look to bad and they work perfectly. So now I think at this point, everthing that goes wrong on lift of or landing is my fault as a newbie pilot, no more excuses.;)

IMG_20170315_234031789.jpg IMG_20170315_234048016.jpg

One more thing I have to mention on the floats design. Although they work really nice now I could observe how they sunk deeper into the water with increasing speed, which I think is the reason that eventually leads to these pirouettes. I can remember that in the FT episode on the Sea Duck they mentioned something about a low pressure pocket forming beneath floats with a realistic design, so they went for the ones with the flat bottom that look more like skids than floats. Is this because of the same physical principles some of you mentioned ealier in this thread when it was about the hull design? And do you think it would be beneficial to swap the floats for some Sea Duck-like ones, if one is looking for a easier build that doesn't require that much precision? Let me know what you think.

Oh, and if you haven't, build this plane. It is great. And from my perspective I can say it works well as a first twin-engine plane for a newbie.

So long! Have a nice day.
 

localfiend

I like 3D printers...
Mentor
Very cool man, thanks for the flight report, I really appreciate it.

Okay, last weekend I had the chance to get flying twice and, first things first, this plane is amazing. It flies nice and easy and it looks absolutely stunning in the air. Concerning my float mechanism, there are a few things I learned and I had to improve.

On my first attempts on starting out of the water, I had a lot of water splashing into the props and also I perfomed a lot of funny pirouettes, very much like in one of the first videos localfiend uploaded. I took me a bit but I was able to get it off the water anyway. Then I "landished" quite hard and destroyed one of the floats. Turns out the weekspot was the hinges glued to the paper, which delaminated from the foam when wet. Back home I tried some tweaks, which happen do work perfectly.

First I adjusted the CG. From my new won experience it is absolutely critical for nice takeoffs to have the CG PERFECTLY centered. Mine was off just a tiny bit to the right, not enough to feel it in the air but the difference on the water was huge. Next I reinforced the glue points for the hinges with a bit of wood, which also made the floats a tiny bit longer.
When the plane now sits on one of them in the water, the other float ALMOST touches the surface but its still possible to see if it sits on the left or right float at the moment.

The last thing I did, was makeing some splashguards so the bow wave doesn't hit the props anymore. They are a bit bigger then scale, but I think they don't look to bad and they work perfectly. So now I think at this point, everthing that goes wrong on lift of or landing is my fault as a newbie pilot, no more excuses.;)


What size are your props? I didn't notice any splash back at all on mine, but I was using 6" props that didn't look nearly as nice as the bigger 3 blade ones you've got. The splash guards are a good idea. I've got a bunch of 3d printable parts I want to make for this plane, splash guards would be an excellent addition to the list.

Good point on the left vs right CG needing to be balanced, that's not something I ever checked on mine. I'd bet that mine was probably a bit off in one direction as well.


One more thing I have to mention on the floats design. Although they work really nice now I could observe how they sunk deeper into the water with increasing speed, which I think is the reason that eventually leads to these pirouettes. I can remember that in the FT episode on the Sea Duck they mentioned something about a low pressure pocket forming beneath floats with a realistic design, so they went for the ones with the flat bottom that look more like skids than floats. Is this because of the same physical principles some of you mentioned ealier in this thread when it was about the hull design? And do you think it would be beneficial to swap the floats for some Sea Duck-like ones, if one is looking for a easier build that doesn't require that much precision? Let me know what you think.

Flat bottom wing tip floats would certainly work better at RC scale, and as the FT Sea Duck is essentially the same size. I bet those floats would pretty much be a direct swap. Another option would be increasing the float angle for the current set.

I really need to do some testing, as I imagine there might be an optimal angle that could make the scale looking floats work well, but flat bottom is certainly easier to mess with.
 

Skillless

New member
What size are your props? I didn't notice any splash back at all on mine, but I was using 6" props that didn't look nearly as nice as the bigger 3 blade ones you've got.

Those are 6040 3-blade props. I've been using them on my other Mighty Minis too, mainly because I think they do look a lot better then 2-blade props on this kind of planes. I basically used F-Pack equivalent electronics and I think with these props the 12 amp escs wouldn't handle full throttle for a very long (measured roughly 16 - 18 amps) but on the other hand they are capable of maintaining cruising speed at about 40% throttle, which I think is incredible.

I think the reason I had problems with the splashing was that the plane was a bit nose heavy at first and also I think my build is a bit on the heavy side with it's three layers of paint, the retracts and the 2200 3-cell I used. Also the CG is pretty high up which caused the plane to pitch down when throttling up on the water and also kept the hull from being self stabilizing on the water, which I think would make for the most scale appearance. Maybe I will perform a few experiments on my own with some ballast far down in the hull...:rolleyes:

Concerning the floats I think flat bottom ones would really be nice to try for fixed floats but were ineligible for the retracts. I think lowered the non-scale appearance wouldn't bother me that much but when raised they would look rather funny as they form the wingtips. Also even the quite slim looking ones from your plans create a remarkable amount of drag, so the plane pitches up pretty violently when retracting them (I had do mix in a lot of elevator trim). With presumeably bulkier flat bottom floats this would be even worse I think.

I've got a bunch of 3d printable parts I want to make for this plane, splash guards would be an excellent addition to the list.

I really like the idea of enhancing foam planes with 3D printed accessories. These kind of details would keep them simple but add a whole new dimension of possibilities for looks and functionality at the same time. Really looking forward to yours and the ones the FT guys mentioned not to long ago, although I am far from owning a 3D printer.
 
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localfiend

I like 3D printers...
Mentor
Those are 6040 3-blade props. I've been using them on my other Mighty Minis too, mainly because I think they do look a lot better then 2-blade props on this kind of planes. I basically used F-Pack equivalent electronics and I think with these props the 12 amp escs wouldn't handle full throttle for a very long (measured roughly 16 - 18 amps) but on the other hand they are capable of maintaining cruising speed at about 40% throttle, which I think is incredible.

I think the reason I had problems with the splashing was that the plane was a bit nose heavy at first and also I think my build is a bit on the heavy side with it's three layers of paint, the retracts and the 2200 3-cell I used. Also the CG is pretty high up which caused the plane to pitch down when throttling up on the water and also kept the hull from being self stabilizing on the water, which I think would make for the most scale appearance. Maybe I will perform a few experiments on my own with some ballast far down in the hull...:rolleyes:

Guess they just look bigger. They're certainly very nice looking. Where'd you get them? Were they painted on the tips to start with or did you do that?

I think the PBY can take quite a bit of extra weight, it certainly flies with very little throttle. When I build my next one I plan to make the battery container go all the way down to the lowest point of the hull. I might even make it continue back further so that I can double up on battery power. A whole nother 2200 would provide a lot of ballast and extra flight time.

Concerning the floats I think flat bottom ones would really be nice to try for fixed floats but were ineligible for the retracts. I think lowered the non-scale appearance wouldn't bother me that much but when raised they would look rather funny as they form the wingtips. Also even the quite slim looking ones from your plans create a remarkable amount of drag, so the plane pitches up pretty violently when retracting them (I had do mix in a lot of elevator trim). With presumeably bulkier flat bottom floats this would be even worse I think.

Does the pitch disruption go away after they're in place? I'm curious if it's drag, or the tips adding more lift to the wing. How fast are you having things retract? Typical servo speed or have you slowed things down? I've only either flown with fixed tips either in the down or up position. Didn't notice any difference in flight with the ones attached to the wings, but that was on the bigger PBY and it was incredibly smooth do to size.

I really like the idea of enhancing foam planes with 3D printed accessories. These kind of details would keep them simple but add a whole new dimension of possibilities for looks and functionality at the same time. Really looking forward to yours and the ones the FT guys mentioned not to long ago, although I am far from owning a 3D printer.

Don't need to own one, just find someone who has one. I bet they'd be willing to print you parts.
 

Skillless

New member
beautiful man! What motor/ESC combo are yu useing?

I used RHD 2204 2300 kv motors with 12 amp Emax Simon Series ESCs.

Guess they just look bigger. They're certainly very nice looking. Where'd you get them? Were they painted on the tips to start with or did you do that?

These are Gemfan props. I got them from Ebay because i couldn't find any 3-blade props this small at my local hobbyshop. I painted the tips myself. Just taped the tips to get straight lines, dipped them into painted and carefully blew on them to make the excess paint drip off. Then I hung them painted tip down until dried and repeated one at a time. If they need to be balanced afterwards you can use some solvent to remove a bit of paint from the backside of the heavier blades. Takes a bit of time but I think it's a nice little detail.


I think the PBY can take quite a bit of extra weight, it certainly flies with very little throttle. When I build my next one I plan to make the battery container go all the way down to the lowest point of the hull. I might even make it continue back further so that I can double up on battery power. A whole nother 2200 would provide a lot of ballast and extra flight time.

That would be awesome. From what I've seen so far it would handle the weight of an extra 2200 without any problems. Would be interesting to see how it changes the characteristics on the water, though.


Does the pitch disruption go away after they're in place? I'm curious if it's drag, or the tips adding more lift to the wing. How fast are you having things retract? Typical servo speed or have you slowed things down?

Yes, they are slowed down. I got one of these servo delay modules because my Tx isn't able to do this. I thought it would look and also fly better and also think it reduces the stress on the moving parts such as hinges and servo.
On my first flight I went for neutral trim with the floats lowered. When I retracted them the plane constantly pitched up until I lowered them or trimmed it with the floats up. I think this is because the floats add a lot of drag pretty low relative to the CG, which is quite high as I mentioned as there's a lot of weight in the wing. (Or is it the "center of drag" in this case? I don't know...)
I didn't think about the wingtips adding extra lift until now, rather the other way round, because with the floats lowered at least part of the wingtip is undercambered, which it is not when the floats are in place. But that was just a total guess as I have virtually no experience in aerodynamics. I'm just trying to understand these things with logic thinking, which can go totally wrong anytime.:confused:

I may have to consult an aeronautic engineering-friend of mine on this one...:p
 
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the-mailman

New member
Oh no, I just got time to finally cut all the foam board and start putting it together, and when I checked the forum to see the build photos they're all gone. I hope I can figure out all these parts. Can they be reinstated?
 

localfiend

I like 3D printers...
Mentor
I was random searching and i came across these pics. should be able to get it built with them. im gonna at least attempt it.


http://s59.photobucket.com/user/localfiend/library/RC%20Stuff/Mighty%20Mini%20PBY-5a%20Catalina?sort=3&page=1

That should be all the pictures. Photobucket exploded and got rid of all their free accounts. It'l be a big mess for me to match up pictures to what they should be again, and might be easier to just build another one and start a new build log.

Would be awesome if the forum software could be fixed so we can upload more than one picture at a time to the website.
 

rockyboy

Skill Collector
Mentor
Would be awesome if the forum software could be fixed so we can upload more than one picture at a time to the website.

When editing / creating a post, go into "Advanced Mode" and look for the button "Manage Attachments". The upload function from that page can upload more than one picture at a time, but you still have to select them individually - can't just upload a directory or do multi-select anymore... :(
 

miraspen

Member
no way!

thats google extension is awesome man. Localfeind howd you make the canopies(design/draw)? id like to use this technique for other planes, i think the spitfire would be my next.
 

localfiend

I like 3D printers...
Mentor
thats google extension is awesome man. Localfeind howd you make the canopies(design/draw)? id like to use this technique for other planes, i think the spitfire would be my next.

I came up with the shape of the canopy by looking at different 3 views and a ton of pictures found online, in this case, the PBY canopy shape is pretty simple.

For the windows and such, I just traced over the outlines from a 3 view inside Doublecad XT. You could do the same thing with a spitfire canopy.

you said you got the parts done? does that mean you had plans? if so, i would love to build it! are they free?

Plans are free and linked on the first post of this thread.