Concept Fleet Product Test, R/C Report 1989
PRODUCT TEST REPORT
By Dick Pettit
Model
1930 Fleet, Model 2
Type
...
..Scale Biplane
Manufacturer
Concept Models 2906 Grandview Blvd. Madison, WI 53713
Suggested Retail Price
..$197.95 (1989 Prices)
Wing Span
84"
Wing Area
.2100 sq / in.
Airfoil
..Semi-Symmetrical
Fuselage Length
.64"
Rec. Controls
4 (El, Rud, Throt, Ail)
Rec. Engine
..1.20 4C, 2 cid gas, or equivalent.
Rec. Weight
18 - 22 lbs.
Basic Materials
Balsa, Plywood, Hardwood.
Instructions
.16 page booklet (see text).
Plans
...2 rolled sheets (36 sq. ft.!)
Hardware Included
...Formed wire gear, cabanes, all screws, bolts, control horns, and cowl mount brackets.
Items needed to complete
..
.propeller, engine, engine mounting hardware, radio, fuel tank/filter/line, wheels, wheel collars (3/16"), control
surface linkages, tailwheel and mount, hinges, adhesives, finishing and covering materials, and dummy engine cylinders.
COMPLETED MODEL
Finished weight
19 lbs. 4 oz. (308 oz.)
Wing loading
21.12 oz/sq/ft
Engine used
Zenoah G-38 (71 oz.)
Propshaft to ground
15-1/4" held level.
Fuel tank used
Kraft 24 oz.
Radio used
.
...Challenger 550 PCM w/6 servos
Covering
.
..Solartex (two 5 meter rolls)
Trim
...........KRYLON Spray Paint and 'Contact' brand adhesive shelf paper. Special items Fiberglass cowl (see text), 6 DuBro Big Wheels, two Ace Noise Traps, CB Heavy Duty leaf spring tail wheel assembly, DuBro 1-1/2 tailwheel, home-made dummy engine cylinders.
CHEERS - Quality and quantity of precision cut wood parts; plans; scale details in instructions; precision fit of parts; dummy engine cylinders construction details.
JEERS - parts bag was open - all the hardware was distributed throughout the box; several screws missing (minor); aileron and elevator -structure appears weak; some rigging details not on plans; questionable method of securing wings to fuselage.
Everyone likes biplanes. You've all heard the line, "Real planes have two wings and round engines". I hadn't built a biplane for several years, so the decision to build another one came at a good time. I recently sold my Aeronca.C-3 and had room for something else. The decision was made to build a big biplane with a gas engine, since most planes of that size need the power of a chain saw powerplant to allow more-than-scale performance.
The next task was to decide exactly which one to get. I got a good deal on a Zenoah G-38 engine from a friend, so that set the engine size for me. After leafing through many, many magazines and catalogs, I decided on the Concept Models Big Fleet. It had the look I wanted and was big enough for the G-38. Construction was stated as being similar to the original aircraft, meaning rib spacing, fuselage stringers, tail group, etc., would all be scale-like. It sounded like a good deal, so I ordered one.
The "Airplane Truck" (my wife's name for UPS) showed up with a relatively large box. I quickly opened it to see what I had gotten myself into, and discovered that I not only got a small lumberyard in wood parts, but had a large assortment of screws, bolts, fittings, etc., floating around inside the box. I suppose the zip-top parts bag had un-zipped itself. Luckily, no damage was done to any of the wood, but it took a while to collect up all the hardware with a magnet.
The rolled plans contained well-inked drawings of all major components, but. also contained many details and comments on such things as servo mounting, cabane construction, engine mounts, etc. Sectional views also made it easy to visualize how things were supposed to look when completed. The instructions booklet contained six pages of actual construction directions, a photo of the completed model before covering, two pages on Kinner K-5 engine details, construction notes for a good-looking dummy engine from plywood and spruce, a parts list showing measurements and material, and several pages of full-size Fleet details including instruments, 3-views, and flight performance data. In all, I think it was quite complete.
Next was the inspection of the wood parts. Boy, did I get a surprise! There was not one die-cut part in the whole kit. Every part, excepting strip wood, was bandsawed and sanded to size. The plywood parts needed a bit of fitting, but everything went together perfectly, with a minimum of sanding pieces to fit. Even the 1/32 plywood cockpit covers fit exactly, requiring only the cockpit holes to be cut out after installation.
THEN THERE WERE THE RIBS! There were several stacks of rib parts rubberbanded together in the box, each one looked smooth and ready to install. But there were so many of them! A rough guess estimated that the four wing panels contained over 250 parts to complete, most of which were already cut to size. I don't mind a kit with lots of parts at all, as long as they fit well.
The instructions plainly state that since most joints in the kit were plywood or spruce to balsa, they do not recommend the use of "super glues", since that type of adhesive does not soak down well into the pores of the wood. Since the model was to use a gas engine, most of which vibrate a lot, I decided to use Elmer's Carpenter's Wood Glue, the yellow stuff you can get at the hardware store at a reasonable price. Concept Fleet also described "double gluing", where you put glue on both surfaces, wait a bit for the glue to sink in, then add a bit more to the surfaces before joining the parts, clamping if necessary. This results in very durable joints. I didn't mind the time necessary to wait for the glue to dry. Most joints could be handled within an hour, but full cure took overnight. Several joints on the fuselage were reglued to strengthen them even more.
The wing panels were built first, starting with eight box spars made of ply and spruce. THEN CAME ALL THOSE RIBS! Each rib was made from three parts; front, middle, and rear, glued to the spars using the wing jigs included in the kit. Half ribs were added on the leading edge. This is what Concept Fleet means by "scale-like construction"; every part is duplicated in the kit, from the same number of ribs and scale spacing to the simulated drag struts running diagonally inside the ribs. The center section construction was essentially the same. Ailerons were built separately, which I reinforced for extra strength. Wing joiners are 3 / 16" ply tongues, each 8" long, held in place by hidden screws under each wing.
Tail surfaces were next, also following scale-like construction, with laminated leading edges for strength. They seemed to be a bit weak, so some 1/8 x l" triangular balsa gussets were added to the structure.
Fuselage construction consists of spruce longerons, balsa diagonals, ply doublers, and balsa stringers. Epoxy was used to construct the motor mount box and to connect it to the front of the fuselage. Epoxy was also used to install the wing boxes and gear mount plates, along with the necessary bracing. Several pre-cut balsa blocks were added to the nose for both shaping and vibration dampening - a nice touch.
My only major deviation from the instructions was in using a fiberglass cowl instead of the balsa block cowl parts included in the kit. I am sure the balsa would have done a fine job, since it was cut to size, needing only gluing and shaping. The instructions state that the model was designed to fit into a compact car (!), since the wing panels, center section, landing gear, and tail group all are removable. Also, since the horizontal stab is bolted on, it is ground-adjustable for flight trim another nice touch.
Rigging a biplane never was a fun-type job, but because of the precision of the parts in this kit, incidences and measurements proved to be exactly what was called for on the plans. I added flying and landing wires, for both strength and scale fidelity. These were made from clevises and 40 lb. fishing leader, clipped to small aluminum brackets fastened to hard-points on the fuselage and wings. Also, tail brace wires were made from clevises and rods, mostly to strengthen the tail group. These additions were not part of the supplied plans, but were built using the supplied documentation. They seemed to give the structure more apparent strength and certainly looks nicer too. I had noticed that the small wood screws used to secure the ply wing joiners looked weak and found the wings could actually move fore and aft with these screws installed. I replaced the screws with 4-40 pushrod wires inserted in holes drilled through each box spar and the wing joiner. This made for a much stronger installation.
There is only one section of the entire airframe which is sheeted, that being the cockpit covering. When it came time to sand the plane, I realized that each and every rib stringer and former needed a good surface on which to stick the covering. Actually, it didn't take too long to complete the sanding operation, beginning with 60 grit and ending with 220 on most parts. Also, since the covering was to be a fabric material which hides a multitude of sins, I didn't bother to get a mirror-like shine on every part. My theory about building an aircraft is: 1. Cut to size, 2. File to fit and 3. Paint to hide.
After, a thorough: coating of Henry Haffke's Magic Elixer (aka, Balsarite) we began the seemingly tedious job of cutting out pieces of covering and fitting them to the framework. The covering of choice was Solartex, purchased from Balsa USA. I got two 5-meter rolls which was more than enough to complete job. This was the first time I had used a low temperature fabric and it really worked well. The most difficult part was trying to cover the fuselage with one piece of material. Actually, I had to use one on the bottom and a big piece wrapped the top. The covering was stuck down on the perimeter with a sealing iron and shrunk with a heat gun.
N-struts, landing gear fillers and cabanes being wooden parts which would suck up paint like a sponge -- were sealed with two coats of clear epoxy paint. This also gave them a look of metal rather than wood.
In order to make the plane look more realistic, dummy cylinders were constructed just as described in the instructions. Believe me, this is a labor intensive operation, mainly because the materials cost less than $5.00 but took over eight hours to complete. The cylinders are made from 1/16" and 1/32" ply disks (150 of them!) stacked on a quarter-inch dowel. Cylinder heads and rocker boxes are cut from basswood blocks. I sealed the assemblies with clear epoxy paint prior to painting
The Zenoah G-38 chosen to power the Fleet was test run prior to installation in the model. Since this was my first gasoline-ignition engine, I had to learn the correct method of starting. This consists of choking until gas is seen in the carb (with the ignition cut off), then at LOW throttle, give it a sharp flip. If it doesn't try to start or POP, it needs to be choked again. I don't want to start a controversy, but I feel that kill switches are necessary for ignition engines. For those not familiar with A kill switch, it is an electrical switch that shorts the magneto primary to ground on an ignition engine. The engine cannot be started and will stop if running. It prevents the engine from being accidentally started by someone nonchalantly turning the prop. 'Nuff said. I added both a manual and a radio-actuated kill switch (over-kill?).
The engine was mounted to the firewall using 1/4-28 hardened bolts and safety nuts. The factory stock muffler was used since the model has an exhaust duct behind the muffler to allow heat and exhaust to dissipate. This area was lined with thin aluminum per the instructions to protect the wood beneath. A Kraft 24 oz. tank with appropriate gasoline tubing was mounted inside the cavernous fuselage. Throttle and remote kill servos were mounted out of the way, but accessible. The receiver and battery were wrapped in foam and secured with rubber bands. A large hatch serves to provide access to all these components.
Prior to painting, I decided to construct all the control rods and servo wire routing. Rudder and elevator servos, being located under the horizontal stabilizer, were easily connected to their respective control surfaces by 6" 4-40 rods and links with keepers. The servo leads were lengthened and an Ace Electronics Noise Trap was added due to the long lead length. Aileron servos were connected similarly using a Y-type noise trap with Deans-type connectors between wing and fuselage. Throttle and kill-switch servos were connected using tube-in-tube linkage to eliminate noise transmission through a metal rod. A 1200 mah battery pack was placed next to the foam rubber wrapped receiver. All servos and electronic equipment are accessible by well-placed hatches in the wing, tail and lower fuselage.
I swore up and down that I had painted my last model several years ago. I had gotten used to many of the pre-finished plastic and fabric coverings and they performed well for me. In making the decision to cover the Fleet with SOLARTEX, I had to search for a better way to put a scale-like finish on the plane without the mess and time of a full epoxy paint job. Then I read an article in High Flight, the quarterly magazine of the IMAA, in which Bob Godfrey described a quick method of painting giant-scale planes at low cost. His procedure is to cover the model with a heat-shrink fabric with adhesive backing, such as SOLARTEX. Then, since most big birds are powered by gas-burners, he simply sprays a coat of KRYLON paint, right out of the can, on the fabric. No priming, no sanding, and best of all, at very low price. I think I paid less than $2.00 a can for the paint, and used six cans. It is applied very lightly for the first coat, followed by a second, heavier coat ten minutes later. This produces a finish which resists gasoline fuels, is very tough, and maintains the fabric look. You can also spray a coat of clear polyurethane paint - flat or satin finish is best - over the KRYLON, and VIOLA!, you have a glow-fuelproof finish. It's something to consider for our next big model.
The color scheme chosen for the Fleet was matte silver for the wings and horizontal stabilizer and bright red for the fuselage, vertical stabilizer, landing gear, N-struts, and cabanes. Flat black Krylon was used on the dummy engine cylinders. I sprayed sticky-backed shelf paper with aluminum KRYLON to be used for some of the markings, such as the FLEET insignia on the rudder. Coaxial cable insulation was split lengthwise and fastened around the cockpits to simulate coaming.
Giving the paint barely enough time to dry, I proceeded to assemble all of the individual parts into something resembling a Fleet. The flight surfaces were hinged using Sig Super Hinges, five on each aileron, three on each elevator half, and three on the rudder. All of the control rods were installed with lock nuts and safety keepers. Final trim details, such as the two wind screens, dummy engine cylinders, and decorative striping, were added last.
FLYING: I decided to go to the flying field one evening after work with a flying buddy to help me. Weather conditions were perfect: low 80's, low humidity for this time of year, and very little wind. The radio gear was range checked with engine off and with engine running at various speeds. No problems were found with the engine, radio, or the aircraft.
It was time. The plane was aimed right down the center line of the grass strip, the throttle was slowly advanced, and some right rudder was added as the planes tail lifted. More throttle and more right rudder kept things in line. After only 50 feet or so, the plane lifted and was flying. I don't think the throttle was past the half-way point, but the plane continued to climb out under full control, and only very slight trim changes were needed to maintain level flight.
After gaining sufficient altitude, stalls were tried to see what would happen. Actually nothing happened, because I could not get it to stall! Low power and full up elevator and the beast just hung in there. So far, so good. I tried a few basic maneuvers; loops were big and round, rolls were very barrel-ish, and stall-turns were a thing of beauty. Slow flight was just that - very slow. High speed flight was only a little faster. Don't get in a hurry when flying this plane. It's solid at all speeds - just not very fast - my kind of airplane!
After about 10 minutes in the air, it was time to set up for landing. I found that at low: throttle the plane would sink a bit, so the descent rate should be controlled with power, not elevator. Aimed at the runway, the Fleet slowly approached the end of the field where power was reduced to minimum, elevator was added to flair and the Fleet settled down to a nice 3-pointer. Flight one complete!
During the course of that evening, I flew the Fleet four times, each flight having equally great results. The Fleet would do almost everything I tried, including spins, snap rolls, and skidding turns - my favorite. Fuel consumption was minimal. I used an estimated 20 oz. of fuel for 35 minutes of flying, At about $1.50 a gallon for the gas and oil mixture, that figures to be less than 25c for fuel. Try that with, a glow engine!
SUMMARY: This project was my first venture into gas/ignition engines, but it will not be my last. Concept Fleet should be congratulated for this model and all the good features the kit includes. I feel it could be as good as any giant scale biplane when flown like the real plane.
Incidentally, this was also the first time I kept records of how much the project cost. Boy, was I in for a shock.! With everything added in; kit, engine, covering, glue, razor blades, pins, paint, radio equipment... everything. Total cost? Just over $700.00. But you know what? Because of the way my Fleet flies, it was worth every penny of it!
Dick Pettit
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Page by: Steve Jones 1/23/2001