HOW TO MAKE REVELL 1/72ND SCALE FLOWER CLASS CORVETTE RADIO CONTROLLED
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Let me preface these descriptions with a quick outline of my experience with this kit. I have built and converted to R/C operation at least six (6) of these kits over the last 25 years or so and they run great with only a few minor modifications. I have one that I have run continuously, every summer, for 20 years. It is a very good model that is well worth the efforts to modify. With that said, let’s look at what I did.
First, it is important to keep as much of the weight as low as possible in the Hull. The model appears to run best with a 40 mm 3-blade prop spinning about 4000 to 5000 RPM. The Rivabo and Raboesch Props work well and the Robbe are not too bad. The Graupner Props are not good and I would avoid them. As for a motor, I would use the Dumas/Pittman General Purpose 6 volt motor ( we can provide a very high quality clone to this motor) or our 545-12, as both motors have good torque at the desired RPM so there is no need for gearing. An eight (8) cell pack of 2400 MaH batteries (Nicad or NIMH) will give at least two (2) hours run time and if placed in the forward section of the hull will balance the running hardware in the back. This will provide a very robust and efficient driveline for this model. To get the power from the motor to the prop without creating a leak, you need a good quality Prop Shaft and stuffing box. You can purchase the Raboesch 300-01 which includes Prop Shaft, stuffing box and hard bronze bearings, or you can make one yourself. If you want to make one, I recommend a 1/8” or 4mm diameter stainless steel prop shaft. Use a piece of brass tubing with a 1/8” or 4mm bore about 1” long for the bushings and slide these into a piece of the next size larger brass tubing. Glue these bushings into the outer tube with a drop of medium superglue. This way, if you need to replace the bushings, the glue bond can be broken with a hot soldering iron (we can make this unit up for you if you don’t have the time or tools). The outer tube should support the prop shaft to just short of the universal. Don’t forget to install an oil tube so that the shaft can be properly lubricated. When installing the shaft/tube, motor and universal, keep everything straight and as perfectly lined up as possible. Any misalignment will waste power and shorten the life of all parts of the driveline.
The final part of the driveline to work on is the rudder. I have always replaced the kit supplied plastic part with a brass one. This is really quite easy. The hardest part is to attach the brass rudder blade to the brass rudder post. I like to use 5/32 diameter brass rod with a 1/32” slot cut into the end. This slot can be carefully cut with a small hobby hacksaw or with an abrasive cut off wheel in a Dremel. It is slow and tedious work but it can be done. For those without the tools or patience, we can supply pre-slotted rods. Once this slot is cut, I make the rudder blade out of 1/32” thick brass plate. To give the model better handling, I usually make the rudder just slightly bigger than the one in the kit. Once the rudder blade is cut, slide it into the slot in the rudder post and position it in the proper orientation. Once lined up, solder the blade to the post. As an alternative to the slotting, you could file away ˝ of the thickness of the rudder post and solder the blade to the resultant flat. In this case I would use a 3/16” diameter shaft. Whichever way you decide to go, the rudder post needs a tube to ride in. This will provide support for the whole assembly and create a water tight seal at the same time (provided that you remember to oil the shaft). The tubing should have an ID the same size as the rudder shaft. Cut the tubing long enough so that when it is installed in the hull the top is just above the waterline. This will help keep it water tight.
Now that all of the Drive and Steering components are upgraded, we need to control the model. A basic two (2) channel radio is just fine. No need for any special features, just a good name brand, basic two (2) channel radio. Same goes for the Speed Control. A good, basic unit rated to 12 volts and 8 amps or so and totally electronic is all that is required. I have been using our Eco-Marine Speed Control. It has all of these features plus it has a simple to use one (1) touch set up and it is waterproof, (also has a 15 amp rating). Once set up I usually stick the speed control upside down underneath the front deck using double sided tape. This keeps the speed control waterproof and away from the motor. Also, while speaking of the motor and speed control, don’t forget to install the noise suppression capacitors on the motor. I also twist the wires to the motor and speed control to keep interference down. Additionally, I try to keep the servo behind the motor and as close to the rudder post as possible while still maintaining easy access to the rear hatch.
The shorter the steering linkage, the less chance there is for flexing and the more accurate the steering response. I like to use ball links at both ends of the push rod to minimize the play in the system. For the rudder steering arm, I use one of the nylon types that the airplane guys use for their steerable nose wheels. They are good, heavy duty units for around $1.50. You will probably have to mount the ball link upside down on the under surface of the rudder arm for proper clearance. I usually set up the throw on the rudder to produce about a 40 degree movement to either side of center.
Now let’s take a look at the receiver and antenna. It is important to keep the receiver off the bottom of the hull in case you take on water. It is also important to keep the receiver wiring away from the motor wiring and power wiring. This will help to eliminate noise interference from the motor. In an effort to satisfy all of these requirements, I mounted the receiver on a shelf installed in the coaming of the aft opening. This places the receiver next to the rudder servo and high enough to keep it out of any water. As a side benefit, it allows the connection from the speed control to have a straight run to the receiver and be far enough from the motor to avoid interference. I usually place the battery and motor wiring along the bottom of the hull and the radio wiring up high in the hull. This creates plenty of separation between all of the noise producing wires and makes the setup virtually glitch proof.
The final piece of the wiring puzzle is the antenna. For the longest possible control range the antenna needs to be stretched out to its full length and mounted vertically if possible. As this is nearly impossible with the flexible piece of wire that the receiver uses for an antenna I used a piece of spring steel music wire for an antenna. The length of the antenna is critical as it tunes the receiver so I had to make sure that the overall length didn’t change. I ran the provided antenna to the base of the funnel and cut it off there. To the cut end I soldered a short piece of 1/32” ID brass tubing. I then cut a piece of 1/32” music wire to the same length as the piece of antenna I cut off of the receiver. I then threaded the music wire down through a hole in the funnel cap and plugged it into the brass tubing “socket” on the end of the receiver antenna. This provides fantastic radio range and the whip antenna can easily be removed when the model is on display so that the overall appearance is not ruined. Before I forget, we have to mount the receiver on/off switch somewhere. The beauty of electronic speed controls is that they don’t draw any power from the motor battery when the radio is off. Therefore, the switch to turn the receiver on and off is the only switch needed to control the whole model. I mounted this switch under the skylight in the aft cabin. This way I can turn everything on and off by reaching under the skylight. There is no need to lift the aft cabin and the less handling the better as this is when parts are broken off.
As far as access to the interior of the hull is concerned, most everything you need to get to can be reached through the opening under the aft structure. To install the main battery I needed an access point through the forward deck in a place that would remain watertight and also not destroy the appearance. The solution I came up with is to enter underneath the funnel. I made the structure that the funnel sits on removable from the deck. It is held in place with magnets. One is mounted on the deck centered under this structure and the other is mounted in the housing proper. To make sure that the magnets are close enough to do their job I had to place a spacer block under the funnel. The thickness of this spacer was adjusted so that when everything is in place the 2 magnets just touch each other. With this done I traced the outline of this housing onto the main deck and then another about 3/16” inside the first outline. I then cut through the main deck along this smaller inside pattern. Once this is done, take some scrap strip plastic and glue it underneath this opening to provide a ledge. Nothing fancy, just enough to provide a lip for the deck piece that you removed to set on. With the deck piece removed the opening is large enough to slide the main battery in and out. When everything is in place, smear a very thin layer of silicone bathtub caulk on this lip and install the cut out deck piece. Once the caulk is dry you now have a watertight seal. When the time comes that you need to replace the battery you can slip a sharp Xacto blade between the lip and deck piece and cut through the silicone seal. The deck piece can now be pulled free and you have access to the main battery. Once your work is done you simply replace the deck piece with a new silicone seal as you did the first time around.
I believe I have covered everything I usually do when converting this kit. I am sure I probably forgot something or didn’t explain it the best way possible. If you have any questions or are unsure of anything please do not hesitate to contact me. I will so the best I can to answer your questions. I can be reached at email@example.com