By Nathan Maat ModelTech P-47D Thunderbolt ARF

Transcription

1 By Nathan Maat ModelTech P-47D Thunderbolt ARF HISTORY Affectionately nicknamed "Jug," the P-47 was one of the most famous AAF fighter planes of WW II. Although originally conceived as a lightweight interceptor, the P-47 developed as a heavyweight fighter and made its first flight on May 6, The first production model was delivered to the AAF in March 1942, and in April 1943 the Thunderbolt flew its first combat mission--a sweep over Western Europe. Used as both a high-altitude escort fighter and a low-level fighter-bomber, the P-47 quickly gained a reputation for ruggedness. Its sturdy construction and air-cooled radial engine enabled the Thunderbolt to absorb severe battle damage and keep flying. During WW II, the P-47 served in almost every active war theater and in the forces of several Allied nations. By the end of WW II, more than 15,600 Thunderbolts had been built. Production P-47B, -C, early -D and -G series aircraft were built with metal-framed "greenhouse" type cockpit canopies. Late -D series (dash 25 and later) aircraft--such as the P-47D-40-RA on display--and all -M and -N series production aircraft were given clear "bubble" canopies, which gave the pilot improved rearward vision. SPECIFICATIONS: Span: 40 ft. 9 in. Length: 36 ft. 2 in. Height: 14 ft. 8 in. Weight: 17,500 lbs. max. Armament: Six or eight.50 cal. machine guns and either ten rockets or 2,500 lb. of bombs Engine: One Pratt & Whitney R of 2,430 hp. Crew: One Cost: $85,000 PERFORMANCE: Maximum speed: 433 mph. Cruising speed: 350 mph. Range: 1,030 miles Service Ceiling: 42,000 ft. INTRODUCTION "It's big and truly beautiful, and just one close-up look at this "Jug" will ignite the fires of flying passion in even the most blasé R/C'er! In World War II, the Republic P-47 Thunderbolt opposed Germany's toughest fighters as it guarded American bombers flying over Europe and it prevailed. That same indomitable spirit lives on in this 1/7-scale reproduction made of balsa, hardwood, fiberglass and plastic. We've spent countless hours in research and development to present you this beautiful ARF. We've given it true-toscale features like an elliptical wing, airfoil shaped, fully sheeted stabilizers, open structure elevator and rudder surfaces, retractable landing gear, factory painted, molded fiberglass cowling, and even a beautiful aluminum spinner hub that's custom made for this aircraft. For those with four-channel radios, we've included the equipment to make the landing gear fixed. When it came time to flight test this warbird, we pushed it to the limit. Oversized engines, forced dead-stick landings, rough fields, and windy days through it all, the "Jug" remained a joy to fly. And a great starting place for those who want to customize and detail the model into something well worth entering into a club level ARF scale contest."

2 Now that sounds like something to get excited about, right? In the next few paragraphs I'm going to explore their claims for this airplane from a modelers perspective to see if what they profess is an accurate representation of the P-47D Thunderbolt ARF. ORDERING AND SHIPMENT: I tend to get a bit nervous when ordering a new airplane, despite what good others have said about it. I read ModelTech's praises, looked at the pictures in the catalog and online, and came to the conclusion this would be a nice introduction to warbirds. I've yet to have experience with a ModelTech ARF, and really didn't know what to expect. It came shipped in a double box as many airplanes do these days, which was nice. However, the P-47 wasn't packaged in the best possible way inside it's own box. When I received mine, it was in fact undamaged and as flawless as when it left the distributor. For that I was pleased, but I would like to see them package this beautiful airplane just a little better. The shipping box did include paper protection to keep things from moving around, but I removed it to take the first picture seen below. CONSTRUCTION INSTRUCTION MANUAL: Instructions for final assembly have been neatly put together in 67 pages. Sounds like a lot doesn't it? Well it is, but they are also a very thorough and complete set of instructions. Detailed in all the right areas, with actual construction pictures. The first few pages consist of recommendations, additional items needed, tools and supplies required, and a kit contents inventory page. There are replacement parts numbers, and a metric conversion chart as well. This is an instruction set that most any builder will be able to follow with ease. WING ASSEMBLY: After assembling the wing, marking and drilling holes for the wing mounting bolts was the next step. It was necessary to trim the tab on the leading edge so it fit snug with the fuselage, but there was still a bit of a gap between the fuselage and the wing. With the wing bolts in place it will be fine. The instructions suggest using masking tape to hold the wing firmly in place while drilling the holes, but I found a second pair of hands to be even more beneficial. My wife [yes, I did say my wife] held the wing in place while I drilled the two holes into the wing, and into the mounting block in the fuselage. Also, instead of setting the fuselage upside down on an airplane stand as suggested, I set it nose down on the bench. This method allowed my wife to apply the suggested pressure to assure a snug fit with the fuselage, as well as making it easier to maintain alignment while I drilled the holes. The instructions state tapping the mounting block is easier than installing blind nuts and is more accurate. I personally disagree, and feel more comfortable with blind nuts, so I used the ones included in the kit. If you're careful when drilling your pilot holes for the wing bolts, using blind nuts should be no problem at all. I also suggest switching to socket cap head screws instead of the machine screws that come with the kit. I've found them in the past to be easier to deal with than a screwdriver and a Phillips head screw. The tail assembly has no surprises. In fact, it was downright simple. Just a little bit of sanding made everything line up very well. After the first setting of epoxy cured, a second was applied to any gaps for additional strength. When that had cured, a little strip of covering on the seem hides everything very well, and cleans up the looks of the airplane. I then installed the ailerons, rudder, and elevator. The covering lined up perfectly, and there were no issues with the fit. On a side note... it sure would be nice when an ARF manufacturer builds their airplanes, if they would simply put and extra couple feet of covering with the kit to allow for trimming the airplane, or accidents to the covering either while building or flying.

3 BELLY PAN: Next I fitted the belly pan to the bottom of the wing. The instructions suggest cutting out the back of the belly pan to allow room for you to install and retrieve the wing bolts from the wing. In my case, I actually cut away the fiberglass, and built a support for the area that attaches to the wing for a little extra gluing area. I also decided to cover it for a cleaner appearance. It also explains how to drill holes in the belly pan for access to the wing bolts. Mine had already been drilled out, so I was able to skip this step. Getting the belly pan flush with the wing for gluing took a bit more time than I would have liked. I did manage to get it to sit nicely, but it did take a bit more sanding and fitting to get it just right. To help any gaps you may have disappear, a little silver covering does nicely to hide the seems. I prepared the surface of the fuselage and wing for gluing the belly pan, by carefully placing wax paper and tape in the appropriate spots. The wax paper keeps the model from getting glue on it where it's not suppose to be, and the tape secures the belly pan from moving. Some 5 minute epoxy, and my two hands to make sure everything was where I wanted it to end up worked great. LANDING GEAR: First was the installation of the tail wheel. I can't imagine a simpler setup for a steerable tail wheel. There's also plenty of room for a retract should you decide. Next is the main gear installation. The kit comes fully equipped with either fixed gear or mechanical retracts. Since I prefer a more scale-like appearance I chose to go with the retracts. I'm finding there are a number of ways to improve the standard setup included with the kit for a more scale-like appearance. The retract installation could be done in multiple ways if you just use your imagination. For the purposes of this review I wanted to try the stock setup, but have some pretty neat ideas for a little customizing of the retracts. Stay tuned, as I'll update this review when I'm done. If you decide to setup the retracts per instructions I would recommend two things. First, while screwing in the servo to the rails, one of them actually separated from where it was secured. A little 30 minute epoxy solved the problem quickly. Second, I personally don't care for the servo connectors included in the kit, so I opted to install clevises instead. I feel there's fewer chances for slop and accidental disconnections using clevises. Other than that, follow the few simple directions and you shouldn't have much of a problem at all. This model really is going together quite nicely, and the opportunities for customization are proving more evident as I get further in the assembly process. I've made a few changes to this point based on personal preference, but I've yet to see a reason why the stock setup wouldn't work just fine. That in and of itself I find unusual and refreshing for an ARF. ENGINE: The kit comes with engine mount beams, which I don't really care for. I think they create more work than is necessary, so I went to my local hobby shop and purchased a Dave Brown one piece mount. It comes pre-marked horizontally and vertically so there's no guess work involved. The firewall of the P-47 was pre-marked despite the directions saying otherwise, which was a nice surprise. I simply lined up the marks on the engine mount to the pre-marked lines on the firewall, and it was perfect. A couple of drops of CA to secure the mount to the firewall provided a secure alignment while I made punch hole marks for drilling. I took a little CA Debonder to remove the CA from the mount and firewall, and began drilling the engine mounting holes. Mount the engine 5-5/8" away from the firewall and you're ready for the next step. NOTE: I did have to make some changes to the carburetor to compensate for the inverted mounting. If I would have left it as it would have impractical to hookup the throttle servo. Fortunately Magnum engines provide an escape for just such a dilemma in that with the removal of two screws the carburetor can be turned around. This solved the problem perfectly.

4 SERVOS & PUSHRODS: After the engine installation is complete the servo's, pushrods, and control horns are installed next. ModelTech created a clever way to install the pushrods which allows for dual elevator horns, and little to no slop. They also used the same idea to connect the tail wheel and rudder to one servo. Nice idea. When installing the servos to the mounts, I noticed the mounts were a little weak. Just like I added additional strength to the retract servo rails, I did the same thing to the aileron servo mounts. One broke free when inserting the screw into the predrilled hole. A little 5 minute epoxy should do the trick. Note, I did install the servo tray backwards. This seemed to allow the pushrods the straightest shot to the servo arm, which I preferred. WING FAIRINGS: The wing fairings were next. I wasn't excited about the instructed method of mounting the fairings so I enlisted the help of a fellow modeler for some ideas. ModelTech's P-47 instructs you to mount the fairings to the wing, then shaping wood blocks for gluing. With a little bit of thought and discussion, it was determined we were going to ignore the instructions and mount them to the fuselage instead. If following the instructions you would shape the wood blocks to the fairings and sand them to fit the wing properly. Once complete you would then mount them to the wing, glue them in place, and secure them for drying with masking tape. The things I didn't care for with this is the time and trouble of getting that tight fit to both the fuselage and wing. It was also determined that it could be cumbersome to mount the wing to the fuselage this way, and still maintain that tight fit. While the directions are very thorough, and it would be an effective way to mount them, It was just more work than I felt was necessary. To mount the fairings to the fuselage instead of the wing, the first thing we did was trim the fairings at the molding lines. With the wing mounted to the fuselage we lined up the fairings as tight to both the wing and fuselage as possible without distorting the fairing too much. This would mean that when the wing is secured to the fuselage it will actually push up the fairings a bit, providing a very tight fit. Once satisfied with the alignment, we made a vertical pencil marks on both the fairing and fuselage for a reference point when gluing. We also traced the outline of the fairing on the fuselage to determine where the covering should be removed. With the wing removed we pulled away the necessary amount of covering from the fuselage for gluing, lined the fairing up with the vertical marks we previously made, and worked our way from the front to the back with thick CA. After the CA had dried, covering was applied for a neater appearance, and a few pieces of tri stock were secured for a little added strength and piece of mind. The time saved, and mistakes prevented by mounting it this way sure did make a difference to this modeler, not to mention it looks great! MAGNUM.91 XL RFS My impression of Magnum 4 strokes from past experience is a favorable one. Myself, and others in my club, have had excellent results with quick starts, smooth idling performance, strong acceleration, and reliability. Therefore, I was pretty excited when I received the XL.91RFS to power the P-47. I've always followed manufacturer recommendations for break-in, and did the same with this engine. This Magnum started easy right out of the box and with a little adjusting was idling great. After I finished about 45 minutes break-in procedure on the ground I decided to test it in the air. I set the mixture just rich enough to see a white tail of smoke from the muffler. Even with this rich setting, transitions are smooth, idling is strong, and my confidence is solid. I look forward to a strong, solid running engine for quite some time out of this Magnum.

5 FLIGHT CHARACTERISTICS Assembly was a breeze, and done very quickly. Let's see how it fly's. Despite popular belief, pre flight pictures have not been a curse to me or my airplanes so I will continue to break the stigma yet again with the P-47. As you can see in the pictures, the P-47 looks as authentic and scale as what many experienced modelers could build. Taxiing did prove a little difficult on the grass runway, but was accomplished due to the fact the grass was very short, and the ground was hard from the cold weather. If the grass were any thicker, the smaller wheels would have a difficult time for sure. TAKEOFF: The P-47 is undemanding and a pleasure to take off. Once you bring the throttle up to full and release the elevator to neutral, the tail comes up as smooth as you'd expect. Very little rudder correction is needed to keep the model straight. Climb out is smooth and predictable. LANDING: Landings need to be flown right down to the runway, but are pretty undemanding. Set up your final approach and come in with about 1/4 throttle. Cut the throttle to idle when the airplane is in line with the runway. Gently let it settle to the ground as you continue to apply up elevator, maintaining level flight with the ailerons. When the airplane settles just off the ground continue flaring ever so slightly until it settles on the main gear. Once on the ground, apply full up elevator to keep it from nosing over, and let it roll out. Larger diameter wheels would definitely be an asset to this airplane, and the winter building months will provide me with the time to make the necessary adjustments. FLIGHT PERFORMANCE: Set up with the instructed control throws, the P-47 is dull to control inputs. For my style of flying, I preferred to use the high rate recommendations for my low rate settings. I also added 30% exponential on the ailerons and elevator. Stalls are gentle, with no real big surprises. It did dip a wing a bit, but regaining lift was rather easy. The Magnum.91 suits this airplane very nicely. It's not a blistering fast airplane, nor a highly aerobatic airplane, but I guess that would not be the point would it? Never having actually seen a full scale P-47 fly, my reading and research leads me to believe this p-47 fly's quite scale like. I've found it to be a very relaxing and docile airplane to fly as you do slow flyby's or high speed passes down the runway. CONCLUSION: The minimal time you'll spend assembling this model, coupled with its high quality and docile flight characteristics, make this P-47 a true joy to own and fly. SUMMARY In some cases assembling an ARF can lead to more frustration for me than had I actually built a kit, and I really do not enjoy building from a kit. I've found so much of this airplane's construction and assembly to be very well thought out, which makes assembly enjoyable for me instead of a chore. The time spent on this model is minimal... under 10 hours in my case. With a few additional hours, and a little imagination, this airplane could really be a show stopper. Overall, I would say the claims in their ad are representative of this airplane. "It's big and truly beautiful, and just one close-up look at this "Jug" will ignite the fires of flying passion in even the most blasé R/C'er! I agree completely. The Jug is in fact a joy to fly! It's a shame the winter weather is arriving so quickly, as I'm itching to get more flights with the P-47. The building season is truly here for this r/c'er, and some of this time will be spent customizing the P-47 to include even more scale like appearances. I plan to apply the decals, paint a WWII pilot, paint the canopy olive drab, install larger wheels on the retracts, and more. Bookmark this review for continued updates to this great American warbird! NOVEMBER, 2002