THE BUILDING SEASON IS UPON US!
POWERING A GIANT RAZORBACK WITH ELECTRONS
As the seasons of the year move from “flying” to “building or assembling,” my mind starts to wander through potential subjects for a new model. When that happens, I usually read a history book or two about the air war in WW II for inspiration. This time around, I settled in with P-47 Thunderbolt Aces of the Ninth and Fifteenth Air Forces by Jerry Scutts. It’s a history of some of the lesser-known squadrons and pilots in the war, and I really enjoyed it.
One of the planes I noticed in the book was a Razorback P-47D from the 325th Fighter Group (FG), which had been flown by the commanding officer, Lt. Col. Robert Baseler. The reason that plane stood out to me was because I had built an RC P-40 way back in the early 1990s and painted it in a color scheme Baseler had used on his P-40F. The trim was a striking black with red, and it had a brightyellow-and-black checkerboard design on the tail, which was the identifier for the 325th FG, “The Checkertail Clan.” Bearing the moniker “Stud” and an ace of spades poker card on the nose, it was a distinctive model. When the 325th transitioned to the P-47, Baseler kept the same nose art but called the plane “Big Stud” since the Razorback was bigger than the P-40. It was a fairly easy decision to do a big P-47 in that livery.
EASY CONVERSION
In the May 2016 Ultimate Electrics column, I detailed the process that I went through to figure out how to convert a Top Flite Giant-Scale Corsair to electric power. I used the Corsair’s projected weight, wing area, and a power guideline of 100 to 150 watts per pound to do the calculations and choose a power system. I had to modify the fuselage and construct a battery hatch and battery deck in the model since it was designed for gas power, and I had to come up with a way to mount the motor. After it was all said and done, the big Corsair flies beautifully—just as predicted—and it has been one of my favorite planes to fly for the last two seasons.
In thinking about a big P-47, I knew that Top Flite offers a nice ARF that’s well built and lightweight, and flies nicely since one of my club mates flies one regularly. The newer version is a Razorback in an olive drab and gray finish that works with my color-scheme plans, and it has the additional advantage of being engineered, from the start, with provisions for electric power. It has a nice hatch built into the fuselage just waiting to be cut out, and the parts for a battery deck are included. Another advantage is that there are no decals or other markings applied at the factory other than a white band on the nose of the cowl.
GO WITH WHAT WORKS
As I looked at the specifications, I realized it was like déjà vu all over again. The P-47 is very similar to the Corsair. The wing area is slightly smaller—1,329 sq. in. instead of 1,376—but not enough difference to really matter. It’s lighter by about 3.5 pounds, which works in my favor because the wing loading will go down, making it easier to fly. I checked the math quickly and confirmed that I can use the same power system and propeller as I did in the Corsair and end up with a higher power loading due to the lighter weight.
I like using the same power system over, and it’s something I’ve done a lot in the past. When brushless motors were first being developed, I figured out that a MaxCim MaxN 32-13Y motor and gearbox combination on 25 Ni-Cd cells would be perfect for a 9-pound model with about a 1,200-sq.-in. wing area, as I planned for a Senior Telemaster I wanted to build. It worked out well, and the next year, I bought another MaxCim and put the same power system in a Sig 4
Star 120. The following year, yet another identical system went into an 82-inch-span Tiger Moth. I’d probably still be buying those motors if they were available. In addition to the calculation-free aspect of this reuse, parts redundancy and familiarity weigh in as additional advantages.
CHANGES
When the big Top Flite box arrived, I started planning the changes I wanted to make. Fortunately, most of them are cosmetic and fairly easy. The checkerboard pattern on the tail is the most obvious and easiest to do before any assembly is done, so I went into the shop to check my covering-film stock. I planned to cut 2-inch black squares, apply them to a yellow background, and then apply it to the tail feathers. Of course, I didn’t have enough of those colors, so I ran to the local hobby shop. I grabbed a roll of each of the two colors and turned to check out. Lo and behold, what did I see? A roll of UltraCote film with perfect 2-inch squares of black and yellow preprinted on it. I had no idea that product even existed, but it made me really happy to know that I wouldn’t need to go through the tedious process of making my own.
Stripping the olive drab covering from the tail parts went well. I had to use heat from a covering iron in some of the more difficult spots, but that’s to be expected. Except for getting the checkered material aligned properly and matching up the squares on the different parts, the UltraCote went on easily. I think the finished parts look a lot better than if I had made the pattern myself, so I’m still really pleased that I noticed that roll of covering in the shop rack.
Next, I decided to paint the cowl with the red and yellow nose colors of “Big Stud.” I thought the factory-applied white band would be a good background for yellow paint, which doesn’t cover other colors well, so I decided just to paint over it. I wiped it down with alcohol, masked off the green and gray behind the white band, and airbrushed a mist coat of Model Master Acrylic yellow. I applied another heavier coat of paint when that dried, and I figured it would be OK to mask off a thin strip before painting the red. The next day I did just that, but before I sprayed the red, I decided to check and see what happened when I lifted the masking tape. Of course, the yellow didn’t adhere to the white factory paint and pulled right up with the tape. I wasn’t happy, but it was good that I didn’t find out later after painting the red color.
I ended up cleaning off the yellow acrylic with mineral spirits, priming with gray automotive primer, then applied a white undercoat followed by the yellow. This time, it worked as expected, and I masked a thin yellow line and airbrushed Insignia Red over the rest. After curing for a while, the masks came off beautifully, and the cowl looks pretty good.
I started the assembly process next, cutting the factory-installed hatch free. The hatch is held in place by wooden dowels in the front and a couple of strong magnets in the rear. It’s well built and should hold up well. I didn’t do a great job of cutting it out, so I’ll need to repair the edges and re-cover the forward top of the fuselage. I really appreciate the designers putting in the nice hatch. It will make it a lot easier getting this plane ready to fly with electric power.
FINAL THOUGHTS
Sometimes taking the easy way out is just fine. Having done electricpower calculations for a model of a given size and type, there’s really no reason to go through it all again for a second similar model.