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30% (3 meter wingspan) Paulistinha P-56 ARF (asembly)

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30% (3 meter wingspan) Paulistinha P-56 ARF (asembly)

Old 01-08-2015, 05:53 AM
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abufletcher
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Default 30% (3 meter wingspan) Paulistinha P-56 ARF (asembly)

I've been posting odds and ends queries regarding my 30% P-56 over on the Scale Forum, but a one thread here (with all my questions) might be more appropriate. I'll start off with a couple photos of the box and its contents. I've got the smaller 80" wingspan version and it flies like a dream, so this seemed like a natural choice. It's designed with a 50cc engine in mind, but my intention is to mount my Seidel/UMS 770 radial, primarily because I need to get some experience in the air with this engine (before I move it to a more serious WWI scale model).

First impressions? It's BIG. REALLY BIG!!!

Second impression? All the parts seem really top quality.
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Old 01-08-2015, 06:02 AM
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Assembly so far has been pretty much a matter of just following the manual. Everything fits and everything is included. I did make one significant change, however. The tail section comes separate from the main body of the fuselage in the shipping box. These two parts are supposed to be epoxied together. But the combined length of the full fuselage, rudder, and engine would make storing this beast almost impossible. So i chose to make the tail unit removable. This mod was fairly straight forward since the rudder and elevator servos are located in the tail and there was already a good tongue-in-groove type connection between the two parts. I beefed that up with some light ply on the inside (with four T-nuts on each side, each epoxied in place) and a 1.5mm ply "washer plate" on the outside. This seems to do the job but I might beef it up a bit more on the top and bottom. We'll see.
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Old 01-08-2015, 06:31 AM
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Next it was time to put in the servos and radio get so I could do an initial manual adjustment of the surface alignments. I always like to get that a close as possible without the radio. As I was doing this, I realized that I didn't actually know how to set a model up for dual elevator servos. Thanks to the kind assistance of the guys over on the Scale Forum, I now have that figured out on my Airtronics RDS8000 (Switch D-EL to active, plug the left aileron lead into ch1 and the right lead into ch7).

I've also set up dual ailerons (naturally) with one plugged into ch2 and the other into ch6) to allow for aileron differential. I'm also planning to use a dual battery/dual switch setup. I started a thread on that on the Scale Forum and it lead to some quite heated (yet still informative) debate regarding whether such systems were truly redundant and the possibly utility of powerboxes and the SmartFly devices. But I'm going with a KISS approach of connecting both switches directly to the Rx.
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Old 01-08-2015, 06:34 AM
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So that's where I am now. The next stage is mounting the engine. Since it's a radial it needs to be mounted a bit lower than the pre-marked cross-hatches on the firewall. And then I'm going to have to figure out where to place the throttle servo and how to do the linkage since it would be blocked by the fuel tank.

Anyone have a clever idea for getting around this problem?
Old 01-08-2015, 06:36 AM
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Oh, and here's my Seidel UMS in action.

https://www.youtube.com/watch?v=II1A3hNj9kc Obviously, I won't be using the kit's fiberglass cowl. In fact, I plan to make my own round cowl from an aluminum pot.

Last edited by abufletcher; 01-08-2015 at 06:43 AM.
Old 01-09-2015, 03:36 AM
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The question I'm asking myself at the moment is should the radial engine be centered on the firewall (which seems aesthetically most pleasing) or whether it should be mounted as high up as possible (to allow for more ground clearance for either a 22" or 24" prop). The difference between these two positions is only about 3/4" so maybe it's not that important.

*****

OK. Made that decision: Centered vertically on the firewall (with zero right thrust). I drilled the holes for the 8mm T-nuts and have them temporarily in place. I'll test mount the engine and if everything is properly aligned I'll add a few dabs of epoxy to the back of the T-nuts to make sure they don't go anywhere.

Last edited by abufletcher; 01-09-2015 at 06:39 AM.
Old 01-09-2015, 08:58 AM
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Here we go!
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Old 01-10-2015, 02:11 AM
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This is its little brother. It's from the same company and has an 80" wingspan.
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Old 01-10-2015, 08:19 AM
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A quick, tentative balancing suggests it's already nose-heavy. I'm now even wondering about putting the Rx and batteries in the tail!
Old 01-15-2015, 04:19 AM
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Small, steady progress. Since the last post, I've worked out the linkage for the throttle servo (which involved fashioning an extension for the carb throttle level), drilled the holes or the metal throttle pushrod, mounted the throttle servo, and most importantly turned a 26cm aluminum pot into a cowl. I still need to come up with a way to mount it. It looks a bit odd, but it gives the ARF an old-timey look while at the same time providing some protection for the rocker heads and rods.

I'm considering painting is red to match the stripes on the fuselage.
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Old 01-19-2015, 06:00 AM
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I've been testing possible spray paints for the cowl. In the first photo below you can see standard auto paint (upper left), 2-part urethane (upper right), high-zinc paint (lower left), and a kind of exterior paint of unknown type (all the labels are written in Japanese). My previous fuel tests with all of these were a failure. But I think the problem was not with the paints but with the amount of curing time I was allowing before testing. So this time I'm going to let these samples cure for a week and then test part of it. If that fails, I'll wait another week and test again. I actually like the look of the 2-part urethene best (very smooth, high gloss). It would be simplest to do the whole cowl in one color. Probably red. The black also looks good (just not in the glare of this photo). I'm testing the zinc for another scale model.

The second photo shows the temporary installation locations for the Rx, twin batteries/switches, glow system and its associated LiPo. This is all just to see how it might fit and to see what problems remain (for example how to route the glow system plugs around the fuel tank and where to install the switches. In the final installation the batteries will be held in with velcro straps so they can be removed for charging.
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Old 01-29-2015, 05:06 AM
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It's taken me quite a while to work out a mounting method for the cowl. In the end, the solution was to bolt the cowl on from behind. The last photo shows an extension for the throttle arm.
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Old 01-30-2015, 06:22 AM
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The next task is to run the 8 wires for the on-board glow system (7 glow and 1 ground). The trick here is getting them around the fuel tank. I've drilled three 1/4" holes in the firewall (2 on top between the brackets and 1 on the bottom below the mount). All the wires will fit through these three holes. The wires on the bottom are no problem as they will run below the tank. The ones on the top, however, will have to be routed through the "instrument panel" area (above the tank). No problem on this ARF.

After that I need to mount a tube that can be used to prime the Seidel 770 before starting. I've already made a tight bend in a 4mm brass tube, cut that off short, and added a length of silicon fuel tubing. This will sit in the 'throat" of the carb. At least that's the plan.

Then, I'll need to add the "plumbing" (3-line system) and finally be able to install the tank and do a final mounting of the engine.

*****

Oops! I forgot I also need to make an extension for the needle valve.
Old 02-03-2015, 04:45 AM
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Grafting the 770 onto this ARF is an matter of solving one problem after another. Current problem to be worked through: The wires for the glow system aren't long enough to reach the Microsens controller and that can't be moved forward because the tanks in the way.

*****

The solution, of course, is to solder up a whole new, longer set of connecting wires. An advantage of the wires is that they hold the tank in place.
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Old 02-12-2015, 05:56 AM
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OK. The fuel priming tube is installed. And that's it for the engine installation! Wahoo!!!
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Old 02-12-2015, 07:53 AM
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It's getting kind of lonely on this thread.
Old 02-12-2015, 11:42 AM
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Keep going, I'm following you.

Bruce
Old 02-16-2015, 09:01 PM
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Good to know I'm not alone in the world. Today I was mounting the engine, hoping it would be the last time, with the throttle linkage, tank and all tubing in place, when I realized there is still one more problem to solve: Access to the needle valve. I had been thinking this would be a matter of an easy-peasy extension but just now notice that the the needle valve is directly in line with the ring exhaust. In other words, the ring blocks a direct line to the needle valve.

This is going to take some thinking.
Old 02-18-2015, 05:05 AM
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Three possible solutions.
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Old 02-19-2015, 05:39 AM
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Here's the needle valve with its finished, flexible extension. i also added a bracket to support it so it's not bouncing around while the engine is running.
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Old 02-19-2015, 08:46 PM
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The radio gear is now neatly tucked in place. This includes the Rx, dual (heavy duty) switches, dual Rx batteries (6V 2000mAh NiMh), Microsens on-board glow system with Microsens glow balancer (which provides even power to each of the 7 glow plugs), and its associated 3.7V 6000mAh LiPo battery.

The fuselage seems in rough balance but I may have to shift things around for the final balancing.

Now back to the easy ARF stuff, like gluing in the windows and applying the decals.
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Old 02-20-2015, 09:00 AM
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Several little, but necessary, things accomplished today...and found the next problem. Seems like there's always a next problem. It's the inflatable tires. Specifically they won't inflate with the needle provided. In fact, the needle doesn't seem to go into the valve on the tires.

So unless I can figure out how this works, I'm going to have to order another set of wheels.
Old 02-23-2015, 09:52 AM
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I've ordered solid wheels (foam interior with rubber outside) in both 5" and 6" diameters to replace the 4 1/2" "inflatable" tires that come with the ARF (which don't inflate).

http://www.kkhobby.com/SHOP/PT186.html

Today I epoxied the main windscreen in place. Actually, I both glued and screwed it in place using smaller servo screws. The windscreen fits fairly well but not perfectly. Tomorrow I'll get put in the side windows.

Given the size and probable weight of this model I've also started exploring better ways of doing the balancing, namely using a "weight and measurement" method similar to what's used on full-scale aircraft. I've ordered a digital scale from Harbor Freight that will do the job.

http://www.harborfreight.com/70-lb-3...ale-95069.html

Let's see, what else? Well, about a week ago I finally painted the aluminum cowl (made from a 26cm cooking pot) using a 2-part urethane spray (red). I also prepared and painted a balsa "shelf" that sits over the radio gear. I'm not sure what the point of it is since it doesn't look at all scale but I painted it grey so at least it doesn't stand out that much. Mostly, it's just a place to put the pilot bust.

At this point the only "parts" left are the windows, some small latches for the door, and the decals. It's certainly starting to seem finished!

Last edited by abufletcher; 02-23-2015 at 09:56 AM.
Old 02-24-2015, 07:19 AM
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The wheels I ordered arrive. Unfortunately, they are rock hard. I fly off a grassy field so maybe that's not too bad. Also after assembling and reassembling the inflatable tires (that came with the ARF) several times and trying several suggestions, I finally found a way to inflate them. First, I needed to wrap a bit of tape around the end of the needle so that it fit snugly in the valve. Second, I had to duct tape the needle onto the end of my compressed air gun. A hand pump just doesn't provide the pressure to force air through the silicon tubing on the inside of the valve.

So now I have a set of 4 1/2" wheels that are a bit soft and a set of 5" wheels that are hard as plastic.

Last edited by abufletcher; 02-25-2015 at 12:58 AM.
Old 02-25-2015, 05:02 AM
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Anybody out there...who is interested in a replacement cowl for their P-56? Since I made my own round cowl from an aluminum pot, I didn't use the kit's cowl. Send me a PM if you're interested.

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