TOP FLITE DOUGLAS DC-3
by Mark Coombs
[Note: Reviewer incorrectly calls the DC-3 a Great Planes kit.]
I've built several of Great Planes' kits before, and being extremely pleased with them, I was immediately interested in their new kit of the DC-3. I'd had my eye on a scale twin for some time and the combination of good previous experience with this manufacturer and a liking for the 'Dak' meant that I didn't have to think too hard when I was offered this kit for review!
The kit was extremely well packed with not an inch to spare - a credit to the packaging designer. The contents revealed an extensive wood pack, most of which comprised the pre-cut parts which were all clearly and individually stamped. All the hardware parts were contained in two bags with the adjustable engine mounts. ABS plastic parts contained those hard-to-shape sections and there were three great decal sheets for an optional military or civil finish. Finally, three huge sheets of plans and an extremely clear and well illustrated instruction book. One excellent feature is the addition of a small scale plan which you can remove from the instructions and use as a reference. With a model of this size, it's a real chore to pour over such large plans to find the required bit of information. Top marks for this idea! Before I start to describe the construction I would like to thank Great Planes for supplying the set of Robart scale undercarriage legs to fit the DC-3. A great looking product, well fabricated in a flat grey finish that will, without doubt, complement this kit perfectly. We will look at these a little more later in the review. I read through the instruction book which covers every conceivable aspect of the model. From tools to test flights, it's all there. I noted that the fuel tanks were positioned in the wing centre section with long lengths of fuel tubing supplying each engine. This seemed a little odd at the time, but it certainly worked in practice.
Plans in place, let's build the tail surfaces
The first job was to build the tail surface skins. In order to make the stabs, two sheets of 1/16" x 3" x 30" balsa were laid together with masking tape on to a flat board. Glue was ran into the seams which were then left to dry. With the skin patterns clearly drawn on the plans to use as templates you can't go wrong. Next, I built the stabilizer. Building over the plans you will find that all the ribs have jig tabs for a flat build. Described in the plans was the use of rib jigs to hold the ribs in position, square, and aligned. The wood needed for this job comes with the kit. No hunting around for leftover scraps of wood. I hate to think how many ribs in the past have split and broken from pins pushed awkwardly into them. Such a simple but thoughtful way of doing this job. It's great when you can build a kit and get useful hints and tips which you can use on other models. The skins fitted precisely and if the instructions are followed to the letter, there's no problems.
Moving on to the fin and rudder, I was given two building options, conventional or scale. Despite being the slower building option due to the complex shape of the fin and rudder, I really wanted this model to be as good as I could make so I opted for the scale version. This was not as difficult as I thought and was far more satisfying to make than the 'easy' version. Once again this section is built over the plans using the jigs to hold the ribs in place. I found my children's notice board pins with their large heads very useful for this job. If you've never made a built up flying surface before, you would have nothing to worry about because the instructions don't just tell you what to do, they tell you how to do it. With the skins in place and a light sanding applied, the hinges were located by using a piece of 16swg wire as a hinge pin. This created the desired movement for the rudder hinge and looked very good.
It was now time to clear some space and tape the plans together in order to view the complete length of the fuselage which is built up in two halves, top and bottom. Construction is from liteply formers with balsa stringers which is very strong and lightweight. I found the job of fixing the stabilizer and fin slightly time-consuming in order to obtain complete accuracy. The instructions recommend weighting down the stabilizer with bags of lead shot whilst checking the alignment. Lacking lead shot I found the next best thing was bags of loose change from the pennies jar! Once this is permanently in place, the next job was to add the sheeting. The builder has all the skin shapes drawn on the plans ready to cut. These are used as templates and is another excellent time saving feature of this kit. Before sheeting the top half, the rudder and elevator rods need to be fitted. These comprise a length of piano wire running through an inner tube which are then fed into an outer tube at 5 mm intervals. This creates a very strong design and positive movement.
At this point it is also recommended that you fit your rudder/elevator servos in place. The bottom half of the fuselage is made in a similar manner and this incorporates the tail wheel assembly. Even the method for silver soldering is included so there's no chance of you having the linkage fail. By the time the bottom skins were in place, the model was really starting to take shape- even if it did look like an airship from some angles! It was certainly light enough. I was now ready to cut, fit and join the first of many plastic pieces. This is a job which I never meet with great enthusiasm, however once completed I could relax and move onto the filling and rough sanding which starts to give me a glimpse of how the completed fuselage will look.
The wing is built in three sections starting with the centre section. I found this to be a relatively quick build taking approximately 1-1/2 hours. Here there is a choice of using retracts or fixed gear so the build will vary according to your choice. The required slots are punched out of each rib and the complete section slotted together. I was then able to place this over the plan, square it up and cyano together. The nacelles are made from liteply that interlocks and automatically gives the correct side and down thrust for the engines - neat. There's a fuel tank for each engine and they are located side-by-side in the centre section of the wing with 18" lengths of fuel tubing running to each one. There's a further 18" run for the tank pressure lines. The fuselage ends up very light with only two servos fitted however, the wings have everything else mounted on them including throttle, flaps and aileron servos plus the engines, tanks and retract systems. When holding the wing only, you feel that it will never fly, but once the assembled aeroplane is handled it seems quite light.
The outer panels are built in exactly the same way as the centre section with pre-cut ribs positioned over the plans and jigging tabs used to form the correct washout. I particularly liked the way the flap and throttle servo are mounted next to each other in each wing. This means that only one access panel is required for each side. Each flap servo drives the end of the centre flap. This flap in turn drives the outer flaps by means of a 1/16" wire running in a brass tube. This is a very strong and safe method. The aileron servos are mounted in each outer panel.
With these completed it was tidy up time to make space for a large enough work surface to join all three sections together. All servo wires and retracts pipework had to be secured before sheeting the entire wing and installing the engines and retracts.
When fitting the retracts it is essential that a perfect fit is obtained so great care should be taken at this stage when fitting the legs. In my impatience to see the overall look of the Robart product I have to admit forging ahead and fitting the complete system in order to operate the impressive air supply control. Robart call this the Air Fill Valve, (part No. 168.) This item allows the builder to adjust the speed of each leg individually and gives such a realistic effect. Fixed gear can be fitted and the pre-bent wire is included in the kit. In either instance, the gear is mounted on hardwood blocks and it's just a matter of following the instructions. At this point I am itching to see them perform on the finished model.
To help me in my engine selection for the DC-3 I decided to contact 'Just Engines' to discuss my requirements. Their advice was greatly appreciated and after a number of phone calls and faxed plans, came to a decision that the MVVS 40 with Pitts exhaust silencer would be the perfect choice. It's good to know the personal touch still exists. With only a small portion of the head visible these engines would fit snugly into the cowl and therefore improve the scale appearance of the model. Three blade propellers have to be used due to the proximity of the fuselage to the nacelles and I chose Graupner 9 x 7 which were a good choice. I have not experimented with any others at the -time of writing. Once the engines were fitted, the nacelles were built up and sheeted. With some more ABS cutting and joining to create the cowls, the excitement was mounting. I can definitely say that the runway was in sight.
Final Construction and Finishing
The wing mounting was a non-event as the wing fitted perfectly on the fuselage. With the alignment checked and double-checked, the wing bolt holes were drilled and captive nuts fitted. The pre-cut ply wing fillet bases were glued in place before fitting the ABS wing fillets themselves.
These huge pieces were glued in place with plastic cyano and all the joints filled and sanded smooth. Finally, the fitting of the remainder of the radio gear, fuel tanks and retracts left me with a completed DC-3 ready for covering. I chose to cover the model with silver Solarfilm and finish it in the civil airliner scheme as shown on the box top. The military option was a version that I'd like to have pursued but the silver and blue scheme made a change from camouflage and the decal set was easy to apply. I originally applied panel lines with a black felt pen but these looked too harsh against the silver. I removed them with a rag dipped in thinners and the finished effect dulled the lines but left some of the effect intact.
There is comprehensive advice in the instructions for flying techniques with twins. There is no feeling that 'you're on your own' and my usual feelings about test flying were noticeably absent. Having put several tanks of fuel through the engines we were ready to go and a bright but cold day was chosen at my local field which boasts both concrete and grass runways. Although I thought I had the engines set up perfectly they still needed some attention and with them both on song I handed the transmitter to my friend Adam Loveday to do the honours. As the wind was quite strong we opted for the concrete runway which gave us more length. We needn't have bothered as the DC-3 leapt into the air after a roll of about 10ft! Adam added a little down trim and the wheels were retracted. They looked fantastic as they slowly moved up into the nacelles. The model was very stable but flying very fast so the throttles were reduced to about half power. Rudder is definitely required in the turns to produce a realistic flight performance. The elevator was set as per the instructions but this created a very over sensitive control and was reduced by half for the second flight. A landing was called and the gear selected to the down position. No flap was used due to high wind speed and with the engines just above idle, the DC-3 made a perfect landing. To me, it was clear that the DC-3 could easily fly on two .25 or.32 engines and still have power to spare. On full power, the Dakota flew around like a pylon racer in a very unscale-like manner.
Much less power was used for the second flight's take-off and a more progressive and scale-like ascent resulted. With reduced elevator movement, the DC-3 flew much more smoothly and as the landing pattern was being entered one of the engines stopped. With half power on the other engine, you couldn't tell that the model was on one engine, except the lovely twin sound had now changed. On the approach the other engine stopped and the DC-3 glided easily onto the runway. This performance impressed everyone and made me feel very safe about operating the Dakota.
The Top Flite Douglas DC-3 is an excellent kit in both presentation and build. I would recommend this as a good scale model for those interested in a twin that really requires minimal building. The end product was a great looking model and superbly complemented by investing in the Robart retracts. The instruction manual guided in great detail with visual assembly photographs and hot tips to help you through. There was also information on the full size DC-3 to obtain exact details. I particularly liked the opportunity to build it as a scale or sport scale model and this flexibility offered by Great Planes meant that the builder doesn't have to attempt anything he's not happy to try. It's the little things that impress really, like having a three foot ruler printed along the base of each plan sheet or having the scale rib positions marked on the rudder, ailerons and elevators. This kit fulfils all my expectations and more. I'm looking forward to many flights with the 'Dak' and I can't wait to see if Great Planes will release another twin. How about a B-25?
Reprinted with permission.
May/June 1999 R/C Scale International Magazine