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Old Oct 29, 2005, 03:01 PM
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Grove City PA basement/park
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DC-3 Guillows conversion

Ok, so its not quite scale modeling, but close enough. First, the wingspan was enlarged to 39.75" (from 35.5) to provide 161sq-in wing area. Stock is about 145, a bit small. It does look a bit like a glider, with the extra wing, but should still look good.
Modifications include:
The center wing panel was lengthened 2 inches. The endswingtips were moved out were 1-3/8" each, adding small strips to the front of the wing formers, to make up for the difference. The wing formers are in there original places, with the solid shaped balsa wingtips moved outward. By doing this, the tapered panels now have a new geometry, thus the need to add a bit to the chord depth, by extending the front of the formers to meet with the LE spar. Shims were used in building, for washout. A cf rod runs through the wing formers and is glued in place. The precision holes for the rod ended up being large hogged out areas, filled with glue. Aileron control is Sullivan gold cable.
Used GWS landing gear mounts, mounted on light ply plates, for the lg mount, as I'm not big on gluing the LG wire into balsa. The tailwhell is steerable. The original nacelle frame pieces were used, lined with cf spar, and joined into the wing with cf spar. The engine was mounted using the front screw mount, using the Guillows wheel halves for engine mounts. Couldn't have asked for a better mount. Spruce blocks were glued to the ends of the nacelle forks, for the engine mount screws to thread into. I have a whole bag of Guillows wheels, since I usually use others. The cowls and engines are removable, and the engines have GWS heatsinks.
I'm using a GWS 300-LI esc. Typical GWS uses nice 20 ga silicone on the batt side, and cheap 22 ga on the motor side, while rating at 15A cont, using heatsink. Soldered 20 ga silicone wire (Maxx Prod) for the motor side. May actually be good for near 15A now.
Edit: Was planning on 3-blade props, but they load the speed 300 motors down a bit much. The litte GWS 4520 props work well on the DD setup. Pn a completely unrelated note, heard the dog barking. Dig it, MA just came in the mail!
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Old Oct 29, 2005, 11:00 PM
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Methuen, MA
Joined Sep 2002
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Scratch,

Looking forward to seeing the progress on this one. Two 300 motors on 161 squares is going to push you towards 15-20 oz/sq ft territory. Might fly like an F-104 Starfighter. Wouldn't a pair of IPS or even LPS motors be sufficient? Should be a very pretty plane. Good luck!
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Old Oct 29, 2005, 11:59 PM
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Quote:
Originally Posted by Mike Tully
Scratch,

Looking forward to seeing the progress on this one. Two 300 motors on 161 squares is going to push you towards 15-20 oz/sq ft territory. Might fly like an F-104 Starfighter. Wouldn't a pair of IPS or even LPS motors be sufficient? Should be a very pretty plane. Good luck!
The 300's are free. Leftovers from GWS EDF bl motor swaps. As for avoiding the Starfighter characteristics, that is why it is 39 3/4" span now. A few have mistakenly tried to build planes like the Guillows B-25, with 300s. Now that is an almost flying tank! Actually geared 180s might have done it, but if I can get it around 16oz, it shouldn't be too bad, and should have sufficient power. Do the math, 16oz on 161 squares is LESS than even your 15 oz/sq-ft minimum. It is 14.3oz/sq-ft. I agree that much above loading does not fly well at all on small planes. To use IPS brused motors successfully, it would have to be unreasonably light.
Well I won't be using the 300 LI esc. Burned out the gate driver at 10A, 9.5V. Soldered on another from a scrap esc and burned out again. I'm convinced the FET has a partial gate short. I wanted the 400 esc, but they didn't have it. Will be using an FMA super. GWS escs all seem to require derating by about 30% on cont current. Used GWS receiver packaging high density foam to line the battery compartment just ahead of the wing. Door will be on the bottom. In this photo, the "glider effect" of the stretched wing can be seen.
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Old Oct 30, 2005, 12:22 AM
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Skunk Water, Rhode Island
Joined Jul 2002
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Hi Scratch, I built this plane 7 yrs ago. Elnarged to 47" for two .049's. This was before mt "E" days. I will finish it for two 7V SP-400's one day.. I hope. I did a MAC CG calc on it, and the CG came on the spar. Good luck with yours! The airfoil seems to be a good Clark Y type with a LE entry.

Steve
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Old Oct 30, 2005, 12:26 AM
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On another note: I was the one who asked Tom barker(Guillows VP) to produce the DC-3/C-47. Only I asked for it in a 45" range span. O well.. can't have everything..

Steve
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Old Oct 30, 2005, 01:20 AM
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Quote:
Originally Posted by St. Martin
On another note: I was the one who asked Tom barker(Guillows VP) to produce the DC-3/C-47. Only I asked for it in a 45" range span. O well.. can't have everything..

Steve
I guess they were trying to save balsa material costs, as they use top shelf contest wood (obviously kidding). It must have been a brand new release, when you bought it. I like the sheeted nacelles on your build. They did finally listen, and make the PBY span a bit larger.
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Old Oct 30, 2005, 03:36 AM
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Canada, ON, Kingston
Joined Mar 2004
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Scratch,

I'll follow this thread! Looks good, even with the extensions, but then again the Gooney Bird always had a glidery look to it anyway.

Now that my Hellcat is finally hanging finished from my ceiling, I'm about to start my next project: the Guillow's B-17. I've been dissecting ESB's great thread on his conversion and will try to duplicate his success.

Keep up the posts!

Steve
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Old Oct 30, 2005, 05:00 AM
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The necells are strip planked. I also started my second PBY. Just another thing to finish..

http://www.rcgroups.com/forums/showthread.php?t=315169

Steve
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Old Oct 30, 2005, 10:05 AM
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Quote:
Originally Posted by St. Martin
The necells are strip planked. I also started my second PBY. Just another thing to finish..

http://www.rcgroups.com/forums/showthread.php?t=315169

Steve
Up early today Steve!? I'd like to see the PBY. Understandably, they are a bit of work. Like to see some pics.
Other Steve: The B-17 was featured in (April 2004?) Flying Models. Joe Behshar (AMA Vice Pres) built it, powering the 2 inner engines. Supposedly a good flyer. One of these days I'll have to meet ESB. He lives about 40 miles away, and seems to be into the Guillows thing also.
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Old Oct 30, 2005, 10:44 AM
Big gov never Works
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Skunk Water, Rhode Island
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I purchase 2 PBY's inthe early 90's, when the wood and the dies were good. I built and flew the first one in the early 90's while living in Fla. This second one hung around in the box for about 12 yrs before I decided to start it. Electrics make it possible and safe. Someday I'll finish it. I buit two of the B-17's. The last one had two SP-400's. I have some pics of it in bare bones on a CD. It sits hanging frome a tail gunners ceiling, about a mile from here. Good airfoil on that one too.

Steve
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Old Oct 30, 2005, 01:54 PM
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Canada, ON, Kingston
Joined Mar 2004
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Hey Scratch,

That is one beautiful PBY; I'd be reluctant to fly it! As a matter of fact, I think I've seen an F6F, a P-47 and now a PBY you've built here on the Zone, and they're all museum quality stuff, if the photos do them justice. Personally, I always struggle with how "scale" I want my models to be. I know that if I spent just a little more time, I could make that cockpit REAL, and although I love building stick and tissue, part of me always wishes I planked the whole thing to get that scale look!

As for the B-17, I ordered the plans and vac form bits from Guillows, and I'm still weighing options. I know two motors would be the sensible thing to do, but then I'd build a Mosquito if I wanted a twin! Maybe four LPS motors like someone suggested while ESB was building his, and I wonder if I could get away with sheeting the whole thing? C of G might be a problem, but foam tail feathers might help, and I could always use NiMHs instead of lipos if I needed ballast. Ah, but then my Stahl Fairchild is pouting because I haven't paid it much attention recently; so much to do and so little time...

Steve
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Old Oct 30, 2005, 11:20 PM
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Originally Posted by Steve85
Hey Scratch,

That is one beautiful PBY; I'd be reluctant to fly it! As a matter of fact, I think I've seen an F6F, a P-47 and now a PBY you've built here on the Zone, and they're all museum quality stuff, if the photos do them justice. Personally, I always struggle with how "scale" I want my models to be. I know that if I spent just a little more time, I could make that cockpit REAL, and although I love building stick and tissue, part of me always wishes I planked the whole thing to get that scale look!

As for the B-17, I ordered the plans and vac form bits from Guillows, and I'm still weighing options. I know two motors would be the sensible thing to do, but then I'd build a Mosquito if I wanted a twin! Maybe four LPS motors like someone suggested while ESB was building his, and I wonder if I could get away with sheeting the whole thing? C of G might be a problem, but foam tail feathers might help, and I could always use NiMHs instead of lipos if I needed ballast. Ah, but then my Stahl Fairchild is pouting because I haven't paid it much attention recently; so much to do and so little time...

Steve
I wonder if four 180 DD motors with GWS 4" or 5" props would work. The little rubber push-on spinners keep it real simple also. I flew an FSK Leonardo 30" wingspan, Piper Cub type plane, with this setup. At 7.5oz it flew with excess power. The motors are considerably lighter than 300s, and considerably more powerful than IPS. Also had the same effect on my 5oz 20" Fly Zone ME109. Definitely an underused setup.
As for cg, the motors are obviously not nose mounted, but since there are 4 of them, it may offset tail weight. My DC-3 is balanced on the main spar now, with lipo just ahead of the wing. I though it would have needed to be moved 1 bay farther forward, but did not.
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Old Oct 31, 2005, 05:12 PM
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Oakland, CA
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Cool project. I don't recall seeing anyone post on a guillow's DC-3 conversion before? You do nice work, I am sure that this will turn out great. One question, you sure about the wing area est? 161 sq. inches seems small to me for 39 inch wing? You might have more area than you think.

Good luck.

Alex
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Old Oct 31, 2005, 10:48 PM
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Quote:
Originally Posted by Rekitter
Cool project. I don't recall seeing anyone post on a guillow's DC-3 conversion before? You do nice work, I am sure that this will turn out great. One question, you sure about the wing area est? 161 sq. inches seems small to me for 39 inch wing? You might have more area than you think.

Good luck.

Alex
Absolutel sure of area. Simple calc: 1 center rectangle+
2x[(tip chord before roundoff + root chord)/2 x tapered panel length]

The wing chord is not very deep, something like 5 inches, which does not make for much area. The tapered ends don't provide much area either. I though about increasing the tip chord, to add area. Look at the tips on a DC-3, and you'll see they taper to almost nothing.

Finished covering and hinging the tail surfaces. Always a task that is nice to get out of the way, as it is not my favorite part of building. The photo below shows the wing panel witht the landing gear mounted in GWS mounts. The area around the the landing gear is sheeted, for a surface to iron on the covering. The wing is mounted using a dowel and a GWS plastic wing mount with nut insert in the rear. The rear mount is glued in with cf horsehair for reinforcement. The aileron servo bottom can be seen, about flush with the wing bot. The top side is where the Sullivan gold cable comes through the partially sheeted wing top, and through a pivoting ez link in the servo horn. In the fuse, a bridge can be seen, reconnecting the center spar, above where it was cut out for servo clearance. Don't want to lose strenght of the center spar. All of this was cf reinforced after the photo. The battery door will be hinged on the fuse bottom. The compartment is lined with shock absorbing foam.
The fuse will probably be partially sheeted, to save weight. I don't think it would look good, with covered spars showing directly behind the smooth plastic canopy and nose. The front area is what is noticed most, and looks much better smooth with sheeting.
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Old Nov 01, 2005, 04:40 AM
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Skunk Water, Rhode Island
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Wow.. nice LG!

Steve
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