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Mar 15, 2016, 02:13 AM
Park Jet Guru
jetset44's Avatar
Funny! Actually, I did originally design this model with flaps but changed my mind late in the design process and eliminated them. I really like having flaps on my models, but I figured that with the light wing loading this model just didn't need them plus I had limited channels on my rx... But lights and a bomb drop, now that would be cool!
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Mar 15, 2016, 01:11 PM
Registered User
That's a beautiful plane, it reminds me a bit of the Martin Mars. I wish I had the skill and patience to build such a detailed plane from scratch.

As for Seattle, we haven't had any snow at all for a couple years except for one or two light dustings. I've lived in this area my whole life and can only remember one serious snow event that stuck around for several weeks. Usually there is a "major" snowstorm about once a decade where we get >1' in some areas that takes about a week to melt away.
Mar 15, 2016, 09:33 PM
Registered User
Fred Sanford's Avatar
Subscribing-just another flying boat fan
Mar 18, 2016, 10:59 AM
Jer. 29:11
jeffsch's Avatar

Builders are Standing By


Ready for plans when they're ready!
Mar 18, 2016, 03:07 PM
Park Jet Guru
jetset44's Avatar
That's great, Jeff! Very cool picture. Glad to hear you're ready to go! Unfortunately I have a few things on my plate at home that I have to finish first (including doing my taxes!) before I can start working on the plans. But I hope to get them done and posted soon, maybe in a couple weeks. I'm definitely eager to see others build this bird!
Mar 18, 2016, 03:18 PM
Park Jet Guru
jetset44's Avatar
Last night I prepped the PB2Y for it's first flight since painting, but got the bad surprise that I had to add an ounce of weight to the nose for balance. In the flight video that I posted the AUW was 38 oz, and the paint job added a total of 3 oz. So I put 41 oz as the AUW in the specs in the first post. However, most of that paint was added aft of the CG, so I had to add nose weight to bring the CG back in line. So the new AUW is 42 oz, still quite light for a model of this size.

Grrrrr, I fight hard to save grams whenever I build a model like this, so adding a full ounce of dead weight is painful. But I'm also flying pretty lightweight batteries (Thunder Power 2100 Pro-Lites, which weigh 6 oz), so the model will still balance fine with a heavier battery pack. I need new battery packs, anyway, so I'll probably just get some slightly larger battery packs for the PB2Y. Better to carry extra flight time than dead weight! The moral of the story is to keep the tail of this bird light if you intend to use lightweight batteries.
Mar 18, 2016, 06:31 PM
Registered User
elewon's Avatar
Yes, one has to be careful adding any weight aft of CG! Good news is you have plenty of room to carry bigger battery and avoid dead weight in the nose.

BTW, don't know how you're doing on 3D WL but with 460 sqin wing area seems like 2D WL is ~12.5-13oz/sqin. I'd have loved to have a simple flat plate wing but don't think that will work. I think WL is heavy enough that one has to be careful about getting the airfoil shape right - one of the issues with building a scale model .
Mar 19, 2016, 02:27 AM
Park Jet Guru
jetset44's Avatar
Yes, a flat plate wing would be pushing it here--but it might be workable if you keep the weight way down and perhaps build a double thickness foam wing and sand it to a semi-airfoil shape. You could go to fixed wing floats, for example, and save maybe 3 or 4 oz (no servos, no retract mechanism). Of course a flat plate wing would really take away from the scale looks, though...

The good news is I was able to get another quick flight in today after work and the model didn't seem to notice the extra weight from the paint job. Flew just the same.
Mar 19, 2016, 06:17 PM
Foam is where the heart is
brett.c's Avatar
Nice build, full of interesting ideas.
Also, always good to see a rare or unusual subject being modeled.
Mar 20, 2016, 07:52 PM
Park Jet Guru
jetset44's Avatar

First water flights


I finally got a chance to fly the PB2Y from water yesterday, and it was a rousing success! The model looks fantastic on water, like it belongs there. Some of my favorite pictures are attached below. I also got some great flight video, but it will take me a couple days to edit the clips into a nice compilation.

The airplane flew beautifully once it was off the water, but the handling on the water was terrible. Slow speed taxiing is quite easy, but once the model speeds up the wing tip floats catch and dig in, causing frequent "water loops" during taxi, takeoff, and landing. Just the slightest bit of wind or wave rolls the model enough for a float to catch. Only about 1 in every 3 or 4 takeoff runs was successful, the rest were rather spectacular failures! I wasn't totally surprised by this, as the PBY Catalina is also known for this since it has a similar float design. But it was still quite frustrating, and makes taking off from water a huge leap of faith. The light wing loading and high thrust-to-weight ratio of this model allows for very quick takeoffs once everything is aligned--you just have to floor the throttle and cross your fingers!
Mar 20, 2016, 08:52 PM
Jer. 29:11
jeffsch's Avatar
She sure is pretty! Really pretty!
Mar 20, 2016, 09:29 PM
Registered User
Wormboy's Avatar
Congrats Steve!
Like you say, she looks very much at home on the water.
Sorry to hear of the water loops, I'm sure the ROW sucess ratio will increase with more flights on the airframe as you figure out its idiosyncrasies (not that you have a lack of experience, far from it. just that every plane is different) Those floats way out on the wingtips certainly make for a long and highly efficient lever when they catch.
Mat
Mar 20, 2016, 11:02 PM
skumgummi dave
Lovely work sir. Thanks for the pics.

Dave-
Mar 21, 2016, 12:28 AM
71% of the world is runway . .
Bart83's Avatar
Very nice Steve. For the next time on the water , try to retract the floats early on the takeoff run. They do this on the ful scale PBY also.
Looking forward to the video , the model looks beautifull on the water.

Cheers,

Bart
Mar 21, 2016, 02:48 PM
Park Jet Guru
jetset44's Avatar
Great tip, Bart! I'll have to try that. The takeoff run at full throttle is only a couple seconds long so it will be tough to retract the floats fast enough, but I'll definitely give that a try.

I think the key problem is that the tip floats just don't have enough buoyancy and can easily become completely submerged, creating tremendous water drag. Interestingly, this is one of the modifications that Consolidated made when they upgraded the PB2Y-3 to the -5 variant--they enlarged the tip floats. I originally designed this model to be a -5, but later changed my mind to do the -3 instead since that's the version my grandfather spent more time in (I actually have his old logbook!). The plans show both versions so future builders of this model can pick either.

The wing tip floats on my model survived at least a dozen high-speed water loops, but the left float did eventually fail from the strain. I intentionally designed in a weak link at the float control horn, since the servo is mounted directly to the main wing spars and the float hinges are mounted to a beefy rib--and those are the LAST things I want to break! The design worked perfectly and snapped right at the control horn, which just left the float dangling freely. I will have to cut into the bottom of the wing to fix it, but it will be relatively simple repair.


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