Specifications Wingspan: 59 in. / 1.5 Meter Wing Chord: 7.5" / 190mm at root, tapering to 3.75" / 95mm at the tips. Wing Area: 358 in2 / 23.1 dm2 Wing Airfoil: AG45, AG46, AG47 Fuselage Length: 41.5" Weight: 10.7 oz. as tested. Wing Loadng: 4.3 oz./ft2 as tested. Radio: FMA M-5 receiver, Hitec Eclipse 7 transmitter. Servos: 2 JR-241 (Ailerons), 2 HS-50 (rudder, elevator) Available From: Oleg Golovidov

Introduction

This past fall I had the pleasure of meeting Mark Drela at one of the Charles River Radio Controllers club events. Mark offered to take a look at a built-up balsa side-arm launch glider that I'm designing and give me some suggestions on how to improve it. While flying with Mark I saw his SuperGee discus-launch glider (DLG) in action and was very impressed. Since I don't have vacuum-bagging equipment, building a SuperGee from scratch was beyond my ability, so I asked Mark to recommend a composite DLG to me. The Taboo XL was one of the DLGs that Mark recommended and seemed to be the best fit for my needs specifically because it seemd to come the most fully prefabricated. I contacted Oleg Golovidov by e-mail and after a few exchanges, I settled on the two-servo (flapperon) wing version. Since each plane is custom-made by Oleg, I ordered my wing customized with my name and AMA number and choose to have mine come with a detachable stabilizer and ballast holes pre-cut in addition to the wing markings. All of these options were very reasonably priced.

Kit Contents

The kit arrived in about 5 weeks, which was right in the middle of Oleg's estimated 4-6 week delivery time -- very reasonable for a custom-built kit with several options added to my specifications. The shipping carton was heavy cardboard and the parts inside were well protected. The Kevlar-skinned wings were shipped taped up in the original foam beds that they were cut out of. My plane arrived with no damage.

The level of prefabrication on this kit is very high. My kit shipped with the carbon fiber pushrods installed in sleeves in the boom and the control horns were installed on the tailfeathers. There is a nylon sleeve installed in the boom for the receiver antenna. The tail group was mounted and hinged, although the removable stabilizer was, of course, shipped removed. Even the nylon screws that hold the stabilizer on were trimmed to the proper length. The finish on the composite parts was very good, and the ailerons came pre-cut with the "live" hinges being made from the Kevlar skin.

Main parts. Tail group detail.

The accessory package is quite complete, including fiberglass cloth for reinforcing the wing joint, a wiring harness and servo wire for the wing servos, carbon fiber rod, shrink tubing, aileron control horns, and the wing hold-down bolt.

By recommendation from Mark Drela, I chose JR-241 servos for the ailerons. Since the ailerons are full span and are used both for control and for flap function, the additional torque of the JR-241 servos made them a good choice and they fit perfectly in the wing without protruding. For the rudder and elevator, I used HS-50 servos that I had. If I didn't have these in my spares box, I probably would have opted for HS-55s. I made the radio battery by cannibalizing a spare parkflyer battery pack. I chose to make a four-cell 280 mAh NiMh pack. Since room in the nose is limited, the pack was made with a stick of three cells end to end with the fourth attached parallel. It's an unusual configuration but fits in the nose of the glider perfectly. To finish up the power for the model I wired up a charging jack. The Yankee in me got the best of me so instead of buying a purpose-built glider charging jack, I manufactured my harness out of parts from the local Radio Shack. Since the jacks from Radio Shack are not shielded, I used several pieces of shrink-wrap to protect the jack from shorting.

I chose to use the FMA M-5 receiver because of it's extreme light weight. With only 5 channels, there is some trade-off in functionality with my transmitter, but I felt it was worth the sacrifices to save the weight. For starters I chose not to install a gyro, but I am definitely considering getting one to try later.

Accessory bag. Equipment.

Assembly

I began the assembly by creating the servo wells by carefully cutting through the Kevlar skin and removing the foam. I marked the position of the servos with low-tack masking tape to both protect the wing skin and to accurately mark the location and shape of the cutout. To protect the topside of the wing,I placed it in the matching foam bed for support while I worked on the cutouts. I'm a conservative builder, so after making the cutouts I lined them with two-ounce fiberglass cloth wet down with foam safe CA for additional support.

Before I joined the wing halves, the exit point for the servo leads were marked on the underside of the wing. The wing needs a hardpoint for the hold down bolt, so I carved a cavity from the foam to accept some micro-balloon filled epoxy. Once these two steps were done, I taped the wing on one side with masking tape, and applied microbaloon epoxy, making sure the hardpoint was filled and the wing was propped up to the proper dihedral to cure. The dihedral angles come pre-sanded and my wing came out to the 19 centimeters of dihedral specified in the manual without any adjustment necessary on my part.

After the epoxy cured, I reinforced the dihedral joint with the provided fiberglass cloth. I chose to wet it with foam safe CA glue. This worked fine but fogged up the fiberglass a little, where epoxy would have given me a nicer looking joint. Once the fiberglass reinforcement cured, I marked, drilled and epoxied the wing mounting pins in place. The foam inside the wing bunched up a bit, probably because I didn't drill carefully enough. I chose to fill the void with epoxy when I glued in the pins since the void was small. I also could have used microballoon filled epoxy. I drilled out the hardpoint for the hold down bolt after dry-fitting. At this point I also did the final shaping of the top canopy cover to make it fit to the top of the wing nicely.

Mouting pins - note marked location of servo lead exits. Hold down bolt and canopy fit.

In order to connect the servos to the receiver in the pod, I modified them by soldering the provided extension wire to them. It's necessary to stagger the splices so the wires will fit in the channel that comes premade in the wing. I also chose to modify the servos by cutting off the mounting lugs and drilling a hole in the servo bottom to allow the wires to exit the bottom of the servo instead of the side. This allowed me to make the servo bays smaller and more snug. It was fairly easy to feed the extension wires through the channels since there were no connectors on them at this point. Once I pulled each extension through the channel in the wing, the provided connector was soldered to the leads. I chose to use all six pins on the connector, even though both servos could have shared the ground and power leads. My thoughts were that this would reduce the possibillty of a catastrophic failure of one servo or radio channel affecting the other. On the mating connector for the servos, I re-attached the plugs I cut off of the servos. As shown in the photo my leads were a bit too short to reach the receiver so I used a pair of 6-inch extensions. This was necessary because I didn't think ahead -- the kit comes with enough extension wire if you cut the leads off of the servo closer to the servo body than I did. This is a great place to apply the "measure twice and cut once" theory.

JR-241 servo modifications. Servo connector block.

Once the servo leads were finished, I centered the servos using the transmitter and receiver. I installed matching servo and taped the servos into their bays with fiberglass-reinforced tape. I prefer this tape because it has good adhesive and doesn't stretch much with changes in temperature. To install the control horns in the ailerons I hollowed out an area of foam and filled it with microballoon-filled epoxy. After the epoxy hardened, I drilled out the hardpoints and glued in the provided control horns with foam-safe thick CA. I installed the carbon fiber pushrods, but because I chose different servos than those recommended, I chose to use plastic clevises on the servo end of the pushrods. The arms on the JR-241 servos have larger holes than the recommended servos. The plastic clevises provided me with a nice slop-free fit to the servo arm.

On the other end of the pushrod I made the connection as described in the manual. I used a L-bend in a piece of piano wire with the long end of the L doubled back on itself to act as a keeper. I attached this to the pushrod with the provided heat shrink tubing. I shrunk the tubing with the pushrod off of the model to prevent the heat gun from melting the foam in the wing. I permanently fixed the tubing to the piano wire and the carbon fiber rod with a drop of thin CA wicked into the shrink-tubing. I've used this technique on parkflyers and indoor flyers before, and even with the larger pushrod and wire it also worked well here. This completed the wing assembly.

Hardpoint cutout. Installed servo, pushrod and control arm.

Next I started loading the equipment into the pod, starting with the nose and working my way back. I installed the battery with several pieces of double-sided foam tape and mounted the charging jack through a hole in the side of the pod. I chose to put this on the left side so the charging jack, which doubles as an off switch when not plugged into the charger, would be plainly visible should I try to do something silly like launch the glider with it still in. To reinforce this idea I put a 1-foot red nylon ribbon on the charge jack. Following the jack I mounted the receiver, which was modified by removing most of the flexible antenna wire and replacing it with the same length of very fine piano wire soldered to the pigtail left on the receiver. I inserted this piano wire into the pre-installed nylon sleeve in the glider's boom. The receiver was secured with double sided tape after the antenna was run. The last items to be mounted in the pod were the rudder and elevator servos. Mounting all of the equipment forward like this prevented me from having to add noseweight to get the model to balance and left ample room for a gyro to be added later.

To mount the servos in the pod, I covered both of them with clear shrink tubing, centered using the receiver and transmitter and then epoxied them in place. The pre-installed carbon fiber pushrods were attached to the servo arms using the same piano wire and shrink tubing method as on the ailerons, only with the ample length of the pushrod. I was able to just use a plain L-bend in the wire and use the pushrod as the keeper. This process was repeated on the control surface end of the pushrods, and once I was satisfied with the positioning both ends of each pushrod were fixed with thin CA.

I completed the final steps to finish up the pod. I ran the leads of the wing servo connector block to the receiver and taped the hatch onto the pod with clear tape. The hatch is sealed along its entire perimeter to provide additional torsional strength to the nose of the pod. It's not designed to be hinged.

Equipment layout in the pod. Tail pushrod detail.

The instructions leave the best step for last, and that's installing the throwing peg. Since I'm right-handed, I installed my peg in the left wingtip. I chose to put my peg right through the carbon fiber reinforcing spar for additional strength. I covered the wing with low-tack masking tape and started with a smaller drill bit to make a pilot hole. This also gave me a chance to double check my alignment. I drilled the final hole to match the peg and I glued in the peg with 30-minute epoxy. Per the instructions I made sure there was a little additional epoxy around the peg to make a fillet between the peg and the wing skin. This completed the build; next step was the radio setup.

Throwing peg installed. Completed Taboo XL.

Radio Setup
I chose the FMA M-5 receiver for its extremely light weight and compact size. I also have been impressed with the reliability of this and other FMA receivers, which was a requirement when considering the significant investment I had in this glider. There always are tradeoffs, and in this case to use the smaller receiver had limitations regarding which mixes were available to me in my Hitec Eclipse 7 receiver. Had I used a receiver with six or more channels, I would not have had these limitations. With five channels I can't use the transmitters preset flight condition switches to adjust the flapperon camber; instead I must use the throttle stick. Luckily could adjust the rates on this channel so each click of the stick corresponds to 1 millimeter of throw on the flapperons. With the throttle stick all the way up I'm in launch camber, two clicks down for search camber, and four clicks down for thermal camber. This leaves me with the rest of the stick's throw for control of the flaps on landing approach. I don't think the amount of control this gives will be much of a problem, but it may take a while to get used to using the rudder without accidentally changing the camber.

The rest of the radio setups were straightforward. The instruction manual provided good detail on control throws, recommended exponential, suggestions on starting elevator to flap mixing as well as center of gravity location in a concise table. I set up my dual rates to give me full throws on one setting and 80% of the recommended full throw on another. The reduced throws were mainly setup to ease the learning curve while the plane was new.

Flying

Even though I started building my Taboo XL in the fall, winter came early here in New England, and overstayed its welcome. I had to wait five months before the snow finally cleared and my flying field was dry enough for a maiden flight. After checking my transmitter setups one last time I began with a few trimming tosses with overhand throws. The initial trimming flights were uneventful. I needed a couple clicks of elevator trim and a click of aileron trim. Once I was confident that the plane was properly trimmed, it was time to take the plunge and give discus launching a try. I started out with some moderately light discus launches, but I quickly moved up to full strength throws. Even without any rudder gyro, the Taboo XL launched straight as an arrow. I found that it was not necessary to release with the nose pointed upward, as the plane would climb nicely on its own after the launch. All that was needed once I had both hands on the transmitter was to nose the glider over at the top. Although this was my first composite DLG, I found the transition from side-arm launching to discus launching easy. My launches quickly eclipsed and then doubled the heights I was used to obtaining with my side-arm gliders. The wind on this first day was unpredictable and gusty, and even my 2-meter powered glider was having trouble. Rather than push my luck, I headed for home after about a dozen successful launches.

Downloads
Type Name Size Launch closeup 679.0 KB Same video, different codec for those whose pc cannot view the previous video. 417.1 KB Launch. 946.4 KB Same video, different codec. 923.6 KB

Since I needed some flight photos and movies for this review, I enlisted help from a friend for my second flying session. Unfortunately before my friend arrived I managed to strip out the rudder servo on a launch. I used an HS-50 for the rudder servo, which is a smaller servo than is recommended. The HS-50 was obviously not up to the stress that the launch put on the rudder. Back in my workshop I removed the stripped servo and replaced it with a GWS Naro-HP servo. While I had the pod open I went ahead and replaced the FMA M-5 receiver with a Hitec Electron 6-channel receiver, which allows me to use my flight condition switches on my transmitter for camber control. With these changes I had my Taboo XL in it's final configuration and I was ready to head back to the field to get the in flight photos and movies for this review.

Downloads
Type Name Size Short Flight. 3.87 MB Short flight, different codec. 3.82 MB Soaring 1.93 MB Soaring, different codec. 2.44 MB

A few days later the weather cooperated with a nice warm day with winds between 10 and 12 mph. After a few trimming flights I was able to start putting the Taboo through its paces. The new rudder servo held up well to even my hardest launches. I also found using the flight condition switches to control the wing's camber much easier than trying to keep track of clicks on the throttle stick. Since this session was during my lunch hour I was actually able to hook up with some marginal lift and get some nice long flights. The performance of the Taboo in light lift conditions is truely incredible. The movies that were taken are limited to 45 seconds because that's the longest my digital camera can take. To get the "Short Flight" video I actually had to use flaps liberally to get the model back down within that time limit. I will expect that in good conditions, speccing out the Taboo will be very easy to achieve and maximum flight times in competition will be frequent.

Downloads
Type Name Size Aerobatics 2.03 MB Same video, different codec. 2.38 MB Glide 2.99 MB Glide, different codec. 2.61 MB Flaps Catch 397.8 KB Same video, different codec. 249.9 KB

In flight photos.

Conclusion

The Taboo XL is a highly prefabricated competition-class DLG. The workmanship and performance of this glider is first class. The manufacturer, Oleg Golovidov, was both friendly and very helpful with any questions that I had. Even though I was new to composite discus-launch gliders, I found the Taboo XL to be easy to fly and forgiving to a beginner discus launcher. I look forward to my skill level growing into this planes full-performance potential. I would highly recommended this glider to anyone committed to stepping up to the top level of hand-launch gliders.