[Courtesy of Pete Young, December 1998 - as published Pete's RCM Soaring Column]
Like just about everyone else reading this article, I am addicted, in a bad way. Even though my fiberglass fuselage Alycone flies great (modified with six servos) and is an excellent contest airplane, as an addicted modeler, I am always looking for the next "breakthrough" sailplane.
Last February, within minutes of each other, I received phone calls from several of my flying buddies. They all said the same thing. There was a new add for an airplane called the "Genesis" advertised in the AMA Magazine that satisfied all this criteria I was looking for. I called the people at R & R Products to verify the specifications and the introductory price. It took me less than a week to make up my mind and order the new kit.
The Genesis is an all new airplane from R & R Products. Unlike their prior efforts, the Genesis is designed from the ground up for thermal duration events. Like most of their other products, the wings are molded. (hollow) The molding of the kit is first class. At the appropriate locations in the finish are recesses the depth and thickness of the tape or whatever accessory needs to be glued in place. The resulting wing in terms of smoothness and airfoil cross section is rather amazing.
The Genesis is available from R & R Products, located at 1120 Wrigley Way, Milpitas, CA 95035, or you can call them at (408) Wings-51. Although the aircraft was originally introduced at $395, the price has recently gone up to $489.
The kit came carefully packaged in a large sturdy box containing all the parts necessary for assembly. The wings, stab, fuselage (with fin), and rudder are already molded. In other words, there are very few pieces to the airplane. A small plastic bag containing several pieces of hardware, such as carbon fiber joiner rods, hinge seal and gap tape, preassembled control rods, clevises and ball links, wing bolt and T-nut connector, etc., were also provided.
All the essential hardware was provided. The only additional materials needed to complete the kit was epoxy and C.A. glue, various grades of sandpaper, a razor saw, rattail file, iron, Dremel tool, countersink, and various drill bits. All surfaces of the model are pre-finished and no painting or covering is required. The kit includes an instruction manual 20 pages long. Because the vast majority of the pieces are already built, there are no "plans". The instruction manual consists of 8-pages of written instructions and 12-pages of photographs and diagrams. The instructions were sufficient, but lacked detail in some areas. Overall quality was very high.
The wing arrives in three separate pieces. The center panel and the two plug in wing tips. R & R provides rectangular carbon fiber joiner rods for the wing tip panels. The wing section is the SD-7037, and with a computer radio is designed for full trailing edge camber changing, both for thermal and tight maneuvers.
It appears the wing is molded from tip to tip in one piece. The joiner boxes and spar assemblies are already molded in place. The fiberglass work was as fine as any I've seen. It appears that the manufacture simply cuts the wing tips off in the proper location and supplies the bent joiner rod to provide a slight amount of polyhedral at the wing tips. When joined, this results in a tight fit at the highest point on the upper surface of the wing. However, there is a large gap along the entire bottom of the wing. You can leave it this way and simply cover the joint with the provided tape. However, I elected to sand the proper angle at the joiner location for a smoother fit. Personally, I think it was well worth the effort.
The wing root sanded relatively easily with 200 grit sandpaper on a two-foot sanding bar. I placed a couple layers of tape over the bottom edge so that I wouldn't accidentally sand in the wrong location.
I also constructed a straight joiner rod out of hard balsa so I could sand a matching leading and trailingedge. The leading and trailing edges of all the wing sections contain a "flash" overhang anywhere between a 1/16 and 3/16 of an inch deep. This is easily sanded off. However, by assembling the wings with a straight joiner rod, I was able to sand a matching leading and trailing edge at the joint.
I like knife edge sharp trailing edges. That's possible with this kit. However, at the trailing edge, I would recommend leaving 1/16 inch of the flash material. Now when you sand the top and bottom to get that knife trailing edge, there is a little additional material to work with.
This is when the mentally difficult but physically easy part begins. You've just spent almost $500 for this perfectly molded wing. Now the instructions tell you to get out an exacto blade and a razor saw and start cutting holes in it. For a couple of hours, I kept finding something else to do. Finally, when I ran out of other things to do I was left with no choice but to begin cutting into the wing itself.
Although I found this portion a little nerve wracking, it was extremely easy to accomplish. The plans call for the use of a razor saw to cut out the ailerons and flap in locations that are marked on the wings. The markings on the wings are very easy to follow. R & R Products has actually placed a recess in the surface (formed in the mold) of the wing where all cuts are to be made. You simply follow the line. A note of caution, other modelers assembling this kit and the Synergy 91 went a little too far with the razor saw and actually cut all the way through the bottom side of the aileron. On the ailerons, you only cut the top surface. The lower surface becomes a "living hinge", which results in an extremely streamlined wing suction. The location of the flap hinge is different on the top and the bottom so you can't cut through both surfaces at one time. The flaps are hinged on the bottom with what appears to be mylar tape that is extremely high quality stuff. Additional hinge tape is available separately from R & R.
Once the flaps have been cut from the center section, you then glue a curved plastic flap gap seal on the top leading edge of each flap. It provides an extremely smooth transition between the upper surface of the wing and the flap when the flap is mixed with aileron. However, when the flap is extended past 45 degrees or so, a gap does open.
The ailerons are gap sealed with a white electrical tape. Again, the leading edge of the aileron surface is recessed half the width and the thickness of the tape. When properly applied, the tape gap seal smoothly flows into the surface of the wing.
Servo hatches are cut in the bottom of the wing by cutting the hatches on three sides leaving the front side as a flexible hinge. The servos are then installed, and the hatches are taped closed with some of the mylar hinge tape provided in the kit. Make sure that you apply the tape to the hatch cover firmly before pushing the servo hatch into place.
The wings are already pre-wired. The wiring runs from a location immediately above the wing saddle to each servo location.
The kit provides a 15-pin connector for use when connecting the receiver to the wing servos. However, this connector weighed nearly 7/10's of an ounce and I elected to replace it with an 8-pin deans connector. I then glued the female connector permanently into the wing. The 8-pin connector works extremely well, and has practically no weight.
Some of you might ask, "How do you connect all four servos and their 12 wires to an 8-pin connector?" Its really quite simple. All your servos are powered by the same power supply. Connect all the positive terminals to two of the pins, connect all the negative wires to another two pins, and that leaves each signal wire with its own separate pin.
You now have to install flap and aileron horns and the servo linkage. Typically, I undersize all my exit holes and then go back and carefully file them larger so that they are only as large as necessary. On this particular model, the size of the openings is of more concern than usual because all of the aileron and flap linkages exit the top of the wing.
I was concerned with the installation method of the servos. They are glued in place using a thick mixture of epoxy and microballoons. As someone who has suffered through a multitude of servo gear failures in the last year, this was a relatively nervy experience. I elected to use a combination of RCD Apollo 24 and High-Tech MH 80 micro servos both in the wing and the fuselage. In all areas except for the rudder, the gear sets are metal. There appears to be more than sufficient power and authority to move the control surfaces. The servos can be removed by pushing on the top surface of the wing and "popping" them out.
Several other Genesis have been constructed in the area prior to mine. They all had the same complaint. Not enough aileron throw. To increase the throw, continue to cut the end of the aileron approximately 1/4 inch ahead of the aileron. This eliminated binding of the aileron when traveling in the up direction. Further, I elected to overhand the gap on the upper side of the aileron using a piece of folded 220 grit sandpaper and sanding a gap approximately 1/16 of an inch. I was able to obtain about 1/3 more aileron throw and am pleased with the overall response of the model. R & R recommends that you mix 25% flaps to ailerons increase role rate.
With the servos in place and using the mixing features of my JR. 347 radio, I was able to obtain a 50% flap to aileron ratio. This improved the roll rate significantly.
In the Pacific Northwest, we often have days of low overcast and no lift. It is important to build an airplane as light as possible. (You can always add ballast if you want to.) The wings didn't leave much, if any, opportunity for weight reduction, so I was hoping that I could find some in the fuselage.
The control mechanism for the tail feathers is all solid wire, push/pull. The stabilizer is fiberglass over rochelle foam reinforced with carbon fiber. The rudder is also a built up piece of hollow fiberglass.
In an effort to reduce tail weight, I elected to construct a built-up rudder and to replace the rudder control system with pull/pull cable. The gross weight of the rudder and control system supplied in the kit was 1.7 oz. The gross weight of the built up rudder with the pull/pull cable was .3 oz. Not only did this result in significant reduction in tail weight, but also results in a reduced amount of counter balance nose weight. I use waxed sail repair thread for my rudder pull-pull cable. I strongly recommend using twisted rather than braided cable. This will greatly simplify your tension adjustments. Simple adjustments to the tension can be made by twisting or untwisting the cable!
Simplify the pull-pull cable system by using one continuous cable for the entire setup. Drill a hole through the leading edge of the rudder perpendicular to the direction of flight. Reinforce the hole with this CA or install a small brass tube. (make sure that there are no sharp corners that may cut the cable) Connect a clevis (or other method of connection) to one end of the cable. Snake the loose end down the fuselage to the rudder. Run the cable through the hole in the rudder, wrap it around the leading edge and back through the hole in the rudder. Now snake the cable back down the fuselage to the rudder servo. Connect the second clevis to the end of the cable (cut to the right length) and connect to the servo. If the cable length is close, just twist or untwist until you have the desired tension. Finally, the distance between the two holes in the servo arm should be exactly the same as the length of the hole (or tube) in the rudder.
I also elected to go with micro servos in the fuselage. I was able to place both micro servos at the very front of the molded servo tray by angling them at a 45 degree angle. The pull/pull cables cross in the center, and travel directly from the servo to the rudder without interference anywhere in the fuselage. Also, the fin is wide enough at the location of the connection of the pull/pull cables to the rudder that all of the cabling is internal and cannot be seen from the outside of the airplane unless you have full rudder throw one way or another. (Note: the rudder supplied with the kit also uses an internal wire guide so that there is no visible rudder horn from the outside of the kit).
The servo tray is molded into the fuselage. This is a very nice feature. The cutting of openings in the tray is necessary and a Dremel tool with the sanding wheel is mighty helpful. The trailing edge of the slip-off nose cone needs to be sanded to fit. The joint between the slip-off nose cone and the fuselage is not as good as one you can make yourself, but the results are certainly acceptable.
The receiver was then slid up underneath the built-in servo tray against the last servo. Finally, the recommended 800 MA battery pack was replaced with a 1200 MA battery pack.
Photographs and the parts list identified a carbon fiber bellcrank. However, the bellcrank that I received looks like it was stamped out of 26 gauge aluminum. Although it appears to work well, I'm not sure if its lighter or heavier then the carbon fiber bellcrank. (Earlier kits received by several of my friends included the carbon fiber bellcranks.)
The bellcrank system and the rocker assembly for the T-tail are very simple to install. I got lucky. I simply drilled holes in locations stamped on the side of the fin and the T-tail lined up perfectly. If you're having problem obtaining alignment, I would recommend aligning the stabilizer pivot tube differently then that recommended in the plans. The plans simply recommend using a triangle to obtain a 90-degree angle between the fin and the stabilizer. However, neither the fin sides nor the stabilizer bottom provide a clean 90-degree angle. Try the following instead.
Leave the alignment of the T-tail rocker arm for one of the very last things you do. Assemble the center section of the wing on the fuselage. Enlarge the hole on one side of the T-tail pivot tube so that it can be properly aligned.
Place a piece of graph paper on a flat workbench, and then turn the entire model upside down. Place a couple of foam blocks under the wings so that the fuselage is fairly parallel to the work surface while the T-tail is resting (upside down) on the work surface. Now align the trailing edge of the wing with the grid lines on the graph paper. If your foam blocks are exactly the same height, the T-tail will now be level with the wing. You then move the trailing edge of the stabilizer back and forth until it also matches the same grid as the wing. Tack the joiner tube in place with C. A. glue, hit it with some kicker, turn it over, and then jam fit the remaining area around the pivot tube with epoxy glue. This will result in a perfectly aligned T-tail with minimum amount of fuss
The method of attachment of the T-tail and its related rocker arm assembly is all internal and extremely well streamlined.
The fuselage wing saddle is not as accurate as I would have expected. So I mixed up some epoxy with microballoons and a little bit of chopped carbonfiber and created my own. I was hoping this would reduce the amount of oil canning of the fuselage in the area where you grip it prior to launch. However, that was not the result. Be careful when gripping the fuselage when launching with a winch, or more importantly, when pulling back a very stiff high start. Several of the Genesis' out here have resulted in surface cracking around the area of the wing saddle, which we believe is from gripping the sides of the fuselage too tightly. There are no formers for bulkhead in this area of the fuselage. If you've got a heavy hand, you might need to install some.
The wing saddle sits above the fuselage on a pylon. If you've ever seen a WWII PBY CATALINA Flying Boat the concept is similar but not as drastic. Free flighters have been using the Pylon to increase stability and reduce parasitic drag at the wing to fuselage connection for years. The pylon also allows the flaps to clear the ground by more than 3/4" in the full down position. I like the pylon wing mount. However, without actual wind tunnel testing its difficult to tell if it actually increases the efficiency of the model.
At the time I ordered my Genesis, I couldn't choose a color. I had to accept the color provided. All four of the Genesis' received in this area have white tops and red bottoms. I'm not sure if this is going to cause any confusion down the road. The finish on my kit was very good. The white tops and fuselages were solid with no fish eyes or swirls. Same is true for the red bottoms. However, this is not necessarily true for some of the other kits received by my buddies. One of the kits received had very little white paint on the upper surfaces or the fuselages. This resulted in a dishwater white with many swirls and color bleeding through. Another kit was somewhere between the one just described, and the one I received, which had no color faults at all. Also, the word ROCHELLE could clearly be read through the red bottom paint on the stabilizer received by one of the other modelers. Because the letters are an inch and a half high, it shows through the paint quite clearly. (He's been joking about changing his name).
The only significantly disturbing finish detail that was in every one of the kits inspected was a very apparent and visible parting seam in the fuselage. I didn't want to add anymore weight to the model so I didn't paint it. One of the other modelers came up with the idea of using automotive trim tape to cover the parting seam. His idea works pretty darn well.
I balanced the model with the C.G. approximately a pencil's width behind the location indicated in the instructions. This required an addition of 2.6 oz. of nose weight. Once I got to the field, I was disappointed with pitch control, the model porposed whenever it flew into the wind, and severely failed the dive test. After a morning of flying, I removed 2.4 oz. of the nose weight. I'm left with .2 of an oz., and I'm considering taking that out.
The first winch launch was down wind. Although I wasn't satisfied with pitch trim, the plane flew surprisingly well and the first flight lasted about 12 minutes.
More elevator compensation was necessary then indicated in the instruction for pitch control with full flaps. Probably the most amazing thing about this airplane is how well it slows down. I thought my Alycone (at 63 oz.) slowed down awful well. The Genesis slows down even better. I haven't had a chance yet to practice spot landings, but I'm impressed with the ability of the airplane to resist rolling from cross winds on approach. The zooming ability of this airplane on launch is truly amazing. The wings simply do not flex. With a slightly heavier wing loading than what I'm used to flying, it just seems to climb forever during the zoom. I've only got a dozen or so flights on the aircraft so far. Many of these were for the purposes of setting up control throw or compensation mixes. But, I'm impressed so far. More later.
I entered the Genesis in a one-day club competition with only 13 flights under my belt. I was leading after the first 4 rounds, and was impressed with the survivability of the airplane. I didn't have the elevator compensation for full-flap fully dialed in, resulting in some deep lawn dart type landings. On two occasions, I buried the airplane up to the end of the nose cone. There was no damage.
The fifth flight was a 3-minute precision. I was able to nail the flight time, but I also nailed my leg on landing. I had made some changes to the elevator compensation with full-flap, and I over-flared at the last minute. The right plug-in wing tip hit my leg so hard it drew blood. After contact, I limped for the next 20 minutes.
I had been adjusting the elevator compensation and went a little bit too far. This time, instead of landing, the airplane flared and flew right into my leg. Although the contact was out of the plug-in wing tip, damage was v ery light. A balsa wood block is used to hold the wing skins apart right before the flap and aileron. This balsa wood piece fractured down the center, but was easily glued back in the field with thick C.A. The 2-56 thread rod used between the servos and the flap linkage was bent almost 25-degrees, but the mylar flap hinge tape was undamaged. A couple of cracks appeared in the fuselage around the wing pylon, but nothing major. None of the servos came loose. Oh well, maybe in the next competition.
I have removed all of the lead weight used to trim the model. Once properly trimmed, the model has an amazing speed range. It slows down to a crawl. The instructions locate the C.G. 5 7/8 inches back from the nosecone/fuselage joint. Final trim located the C.G. 6 5/8 inch back from the nosecone/fuselage joint. I'm used to flying airplanes with lower wing loading and learning to fly at a higher speeds has been more difficult than I thought. Later the tow hook was moved back the same amount and the resulting launch is almost vertical.
After removing the nose weight, and building the model with a built-up rudder, the final flying weight of the model is 64.6 oz. If another 5 oz. of weight could be lost, this would be a truly phenomenal airplane.
I used metal gear high-tech HS80's on all control surfaces except the rudder. (I didn't think metal gears there were necessary so they weren't used). The servos have taken an incredible beating and none have stripped. However, the metal gears don't allow very accurate centering and I'll probably be replacing them in the future. I'll either replace the elevator servo with a dual-ball bearing servo or replace the elevator and both the flap servos with JR-341s
Even though the model flew great, I was still dissatisfied with neutral elevator settings. Stalls were still too frequent and consistent thermal turns in turbulent air were still to difficult. I was just about to change the elevator servo to dual ball bearing under the belief that I had a centering problem. After reading about turbulators on the bottom of the elevator of a ASW-24 I decided to try it on the Genesis first.
I turbulated the bottom of the elevator with two layers of automotive trim tape at approximately 30% of chord. I was truly flabbergasted by the change in flight characteristics. The model required four clicks of down trim to compensate for the turbulator. The dead spot at neutral elevator completely disappeared. Pitch control smoothed out considerably. I would highly recommend a little experemention.
This is an extremely well-priced kit. Although I spent approximately 35 hours of construction time, it could have been done in as little as fifteen. It has exceptionally good flight characteristics and thermals very well. A computer radio is necessary. If you can mix elevator to trailing edge camber and increase camber approximately 1/8 of an inch with full-up elevator, it does amazing things with the flight performance.
This is a great airplane. After approximately 60 flights and turbulating the elevator, I've become very familiar with this aircraft.. Many people at the flying field have asked me if it flies better than the Alycone. It doesn't fly any better, it just flies different. The Alycone is a slower flying airplane, and can thermal better than any plane I own. It will stay up in air warming up off the grass and is the most spiral-stable airplane in my inventory. The Genesis has a much higher speed range and will out climb the Alycone in strong thermal conditions. It is very very resistant to cross wind induced roll which has resulted in higher landing scores.
For the price, this airplane is hard to beat. It thermals great, flies great and lands slow. You'd be happy with this airplane, and I strongly recommend it.
Sherman Knight is a member of the Seattle Area Soaring Society and flies out of the 60-Acres flying field in Redmond, Washington.