[Courtesy of Pete Young, December 1998 - as published Pete's RCM Soaring Column]
The Model Electronics Corporation Minimax-700X is a two meter span (78.6") radio controlled sailplane designed for first time builders as well as expert glider fliers. It's a high lift, slow flying plane with lightweight construction and with all parts machine-cut to extremely close tolerances. Our kit arrived neatly packaged in its 39"x6"x2" box with all parts bundled together and neatly marked for its intended usages. The kit supplies an unusually complete set of hardware - nylon tube-within-tube linkages, ball-links, control horns, c/a hinges, servo linkages, etc. This sure beats running out for some miscellaneous item to complete the model, that's for sure!
From a design point of view, the Minimax features a modified Gottingen 385 airfoil; the resulting airfoil is flat bottom with approximately 10.4% max thickness at the 32% chord point. The one-piece wing is assembled in three sections - a flat center section and two tip panels - and the -700X option includes the pre-fabbed parts to bolt the wing to the fuselage with 2 1/4" nylon bolts. The wing layout uses 1/32" balsa sheet for top and bottom sheeting from the leading edge back to the spars, with 1/32" balsa top & bottom cap strips from the spars to the trailing edge. Tail surfaces are conventional balsa truss construction and the fuselage is all balsa sheet with stringers in the corners.
CONSTRUCTION: Our kit assembly started with the wings and we were immediately impressed by the extensively detailed building instructions. The 32 page instruction manual is printed on double-sided 11" x 17" sheets and includes 184 photos and drawings of excellent quality, accompanied by extensive step-by-step instructions, 174 steps in all. The written and illustrated instructions are very very complete and really do a superior job guiding builders through the building processes - 52 individual photos and steps are devoted to the wing assembly alone!
During the actual wing construction itself, we were also impressed by the absolute precision of the machine cut ribs and the supplied balsa and spruce stock - all pieces were highest quality and fit together with uncanny tolerances. We happen to have assembled quite a few airplane kits over the years, and the fits and tolerances of this kit put it in the "best ever" category for this reviewer - there are some laser-cut kits currently being produced not as good as this one!
Our construction of the wing went along quite smoothly, aided significantly by the dead-on tolerances, the detailed instructions, and the clearly illustrated rolled plans. We had some initial concerns that the 1/32" balsa wing sheeting could present handling problems but found this not to be the case - just be sure that everything fits tightly since you won't be able to "sand away" any mis-assembled fits! For adhesives, we rely on Satellite City "Hot Stuff" c/a products which we have used and trusted for over 25 years of model building.
Construction of the horizontal and vertical stabilizers is very straightforward and should not present any problems for first time builders - just to be sure, the illustrated instructions provides 36 individual photos detailing the building, covering, and hinging of the tail feathers!
The fuselage is straightforward to assemble and the resulting structure is light and strong. I did deviate slightly from the instructions which call for the fuselage sides to be cut halfway through, top to bottom, then glued to give a slight taper to the forward fuselage; I simply bent the fuselage sides together once the main fuselage formers had been bonded to the fuselage sides. By the way, I never did figure where to install former F2A which is supplied but not called out in the instructions or shown on the plans - I guess I didn't really need this piece after all!
The bolt-on wing option provides 2 sets of pre-drilled and tapped balsa blocks which fit into the wing and to the fuselage sides. Just to insure that the fuselage blocks would not loosen in shear, I ran short sections of hardwood dowel sideways into those blocks through the fuselage sides.
FINISHING: I used Top Flite Monokote to cover the flying surfaces with a combination of black on the undersides for visibility, and yellow and orange on top for contrast and visiblity; as per our usual practice, we used Coverite's Balsarite to prepare the flying surfaces for the iron-on covering. The very striking vinyl graphics were supplied by Comp-U-Cut Vinyl Products (976 W. Foothill Blvd., #328, Claremont CA 91711, (909) 624-2906). Don McColgan has an extensive supply of custom fonts, styles, and unusual highlight effects, all at extremely reasonable prices.
The fuselage was finished by first sealing the grain with two thin coats of nitrate dope, followed by Century 21's spray primer and Gloss White paint, for a light and durable finish. To help protect the nose underside, I attached a tough polyethylene plastic "shark's tooth" skid from Tim McCann (P.O. Box 2091, Harrison ARK 72602). Tim sells a variety of glider skids and skegs which are easy to install and virtually unbreakable.
EQUIPMENT: Standard radio equipment fits easily into the fuselage, so I decided to install a new Hitec Focus 6 radio system into this plane, installing two Hitec standard servos into the forward fuselage. The plans and instructions show the pushrods connecting to the servos close to the fuselage centerline, with the nylon tube linkages making a series of fairly long unsupported runs to the rear of the fuselage. This could pose problems with tubes buckling under load, so I instead fastened the exterior tubes directly to the fuselage sides, spacing the servos so that they latched directly to the wall-mounted linkage tubes.
With a 450 mah battery pack in the nose, I thought initially that I wouldn't need any nose weight at all - flight tests showed the need for an ounce of nose weight, so my final flying weight came in at 29 ounces for a 5.6 ounces/sq ft wing loading, a pretty light weight for those 720 square inches of wing to carry around. I imagine that with micro radio gear and a smaller battery pack, I could have come close to the kit's suggested 19 ounce flying weight, but instead preferred the extra robustness of standard sized radio equipment. It's the builder's choice, either way will work!
FLYING: After several consecutive weekends of rainy and windy weather, a Saturday morning dawned clear and sunny, a trifle chilly but pretty fair for a New England late fall day. First glides at the local flying field showed the need for a ounce of nose weight, as noted above. First flights were on a fairly short high start intended for smaller gliders. These launches released at fairly low altitudes so were not very conclusive. I switched to a heavy duty high start that I routinely use to launch 120" Open class gliders - now that really made a difference! The Minimax's D-tubed wing stood up to the increased launch velocities with no problems whatsoever - and the extra altitude gained really paid off with longer flights in light thermal conditions. I was very pleased by the plane's handling qualities and gliding performance which were totally pleasurable to experience. The plane turns easily into thermals, rides them well, and has excellent penetration into moderate breezes.
After I had completed a dozen or so flights, a jogger came over who expressed an interest in this remote controlled model airplane. I launched the Minimax-700X, trimmed it for "hands off" stable flight, then turned the controls over to this totally "zero time" flier with just a few words of instructions. It may have been beginner's luck but the soaring conditions over the field just happened to go "excellent" during this flight, and a 3 1/2 minute flight resulted. The jogger/flier said that the plane was so easy to fly that it flew itself most of the time and he had no problems controlling, despite never having flown an R/C glider before. We exchanged addresses and I believe I may have created a new R/C glider flier that morning. All in all, this was the perfect ending to a very nice construction and flying evaluation.
SUMMARY: The Minimax-700X is probably one of the highest quality glider kits that I have come across, in terms of instruction quality, materials, and flying performance. Built and flown carefully, it should provide the builder with many hours of fine soaring performance and I recommend it highly for pleasurable two-function flying. Buy it, build it, and experience the fun for yourself!