TOP FLITE ELDER 40
by Walt Wilson
Aircraft Type: Semi-Scale Sport
Mfg. By: Top Flite Models
Dist. By: Great Planes Model Dist., P.O. Box 9021, Champaign, Illinois 61826; www.top-flite.com
Mfg. Sug. Retail Price: $159.99; Street price $99.99
Available From: Retail Outlets
Wingspan: 65 Inches
Wing Chord: 12.125 Inches
Total Wing Area: 778 Sq. In.
Fuselage Length: 49.5 Inches
Stabilizer Span: 21.25 Inches
Total Stab Area: 172.65 Sq. In.
Mfg. Rec. Engine: .40-.46 2-stroke; .52-.70 4-stroke
Rec. Fuel Tank Size: 10 Oz.
Rec. No. of Channels: 4
Rec. Control Functions: Rud., Elev., Throt., Ail.
Basic Materials Used In Construction
Fuselage: Balsa, Basswood, Plywood
Wing: Balsa, Basswood
Tail Surfaces: Balsa
Building Instructions on Plan Sheets: Yes
Instruction Manual: Yes (40 pages)
Const. Photos: Yes
Radio Used: Futaba 6DA, 4 Servos
Engine Used: O.S. .46 FX
Fuel Tank Used: 10 oz.
Weight, Ready to Fly: 93 oz. (5 lbs. 13 oz.)
Wing Loading: 17.22 oz./sq. ft.
WE LIKED THE: Matching of balsa hardness to application, clean die- and laser-cutting, ease of construction.
WE DIDN'T LIKE THE: Minor errors and omissions in plans and illustrations.
World War I was the venue for the introduction of air warfare. Throughout the war, biplanes and triplanes became the state-of-the-art, incorporating the materials and technology available at the time, but some of the earliest combat planes were monoplanes. The Top Flite Elder 40 isn't a scale model, but an aerobatic sport plane that has the appearance of some of these early fighters. The Elder isn't a new model, but the Gold edition version is a new and improved kit using Top Flite's latest laser and die-cutting technology and CAD (Computer Aided Drafting) drawing techniques.
The kit comes in a colorful 37.75" x 7.38" x 4.5" box, which includes a description, dimensions, and recom-mendations for engines, radio con-figuration, and accessories required to complete the model. Several photos of features on the plane are also included. Opening the kit, I found two rolled 36" x 46" plan sheets and a 40-page instruction manual. There was also an addendum page correcting the location of the wing hold-down blocks as shown on the plans. The wood was rubber-banded together in groups, according to size and type. Upon inspection, all the wood was straight, not warped, but some of the soft balsa sticks were damaged by the rubber bands. Various hardwood blocks and hardware were packaged in plastic bags and a engine mount was included. The fuselage and wing are to be built from plywood, basswood, and balsa. The tail surfaces are built up from balsa sticks and some die-cut pieces. As with most Top Flite kits, some parts must be assembled by laminating thinner die-cut pieces of balsa or plywood, instead of being cut from one piece of thicker stock.
The instruction manual is very well-done and thorough. Construction starts with the stabilizer and elevator. I used Great Planes Pro CA and Pro Epoxy throughout this project. Using thick CA, construction is quick and simple for the stabilizer and it seems to be very sturdy. The basic structure is 1/4" balsa sticks with laminated die-cut tips. Capstrips, top and bottom, support the joints and are shaped to give the stabilizer a "ribbed" look and airfoil section. No problems were encountered. The fin is built the same way.
Tapered trailing edge stock is provided for the ailerons, but the rudder and elevator must be planed and/or sanded to a tapered shape from sheet stock. It would have been nice if they would have provided tapered trailing edge stock for them, too.
The author used the steerable tail wheel option for good ground handling on paved runways. Open structure is finished with Flat Clear LusterKote. The MonoKote was cut away where the stabilizer is epoxied to the fuselage structure.
Wing construction is traditional with no new innovations or mysteries. The wing has basswood main spars, shaped balsa leading and trailing edges, and plywood center joiners. The rest of the structure is balsa. The die-cutting is clean and the density of the balsa seems to have been carefully selected for each application. Where strength is required, the balsa is hard. Where carving or shaping is required, the balsa is softer. It's refreshing to see this in a kit.
Construction appears to be so obvious that, during the wing construction, I made my first mistake on this project. The instructions say to put shear webbing along the front of the main spars. The photo illustrating the shear webbing shows eight pieces going all the way to the center rib (this will be corrected in future kits). I charged ahead and installed eight pieces of shear webbing, like the photo. Upon looking at the photo again, later, I realized that only the outer six were annotated. The plans show the center joiner in front of the spars at the inner two bays, but when working from the back of the wing, one may not notice the difference until it's too late. Later, when it was time to cut away the center ribs and install the 1/16" plywood joiner to the front of the spars, I realized that shear webbing occupied that space.
No problem, the joiner can simply be installed at the back of the main spars. With the shear webbing boxing the spars in front, it's probably stronger anyway! Otherwise, completion of the wing went as instructions directed with no problems. With the 1/16" plywood center joiner and 1/8" joiners on both the leading and trailing edges, the wing is probably strong enough to withstand most maneuvers. Call me cautious, but I also fiberglassed the center joint for additional strength. The end result is a very strong wing.
Sir Reginald is ready to go seek out the Huns! His trusty Vickers machine gun is ready.
Fuselage construction begins with edge-gluing the upper and lower die-cut, rock-hard balsa sides. Doublers are edge-glued together and laminated to the sides. Landing gear support pieces are then laminated to the doublers. The longerons are 1/4" basswood in 36" lengths. The upper longerons are to be spliced together to make the required length. When the upper longerons are glued to the fuselage sides, with the splices in the position shown on the plans, the rear parts of the longerons aren't long enough to overlap the rudder posts. I epoxied the 1/4" rudder posts to the rear of the upper longerons, rather than between the upper and lower longerons as shown on the plans, and was still about 1/8" short of the length shown. The tail moment on this Elder is just going to be 1/8" shorter than the plans show! If you build one of these from an early kit, move the splice aft 1/2" from the location shown on the plans (the plans will be corrected in future kits). The front portions of the spliced longerons are more than long enough to allow this change.
The open framework of the aft fuselage looks frail, but is actually very strong when the basswood structure is reinforced with the laser-cut plywood braces. Fuselage formers are keyed to the sides and all fit beautifully. Except for the open framework, basic con-struction is very straightforward and presented no problems. Throughout the construction process, the instructions keep telling you to use scrap 1/4" x 1/4" basswood for various purposes. They only provide five 36" pieces, and I had to go buy more just to finish the structure of the aft fuselage! Future kits will have six pieces of this stock.
The firewall has 2 degrees right thrust and 5 degrees down thrust. The firewall-to-fuselage joint looked a bit fragile to me, so I reinforced the sides and bottom with fiberglass on the inside of the fuselage.
The O.S. .46 FX is mounted with the cylinder at a 45° angle for muffler clearance and to avoid fouled glow plugs. The landing gear is preformed and goes together nicely.
The firewall has dimples for the drilling locations for the engine mounts, if you're using an inverted O.S. .46 FX or O.S. .52 FS engine. The stock muffler for the .46 FX won't clear the cowl with the engine inverted. I am not fond of inverted engines because of potential plug fouling resulting from oil accumulation in the head. You can always start the plane upside down to clear the plug, but there's a better way. I mounted the O.S. .46 FX with the cylinder at a 45 degrees angle. This serves two purposes. Minor oil accumulation in the head won't foul the glow plug and the stock muffler is under the fuselage, helping to keep the plane cleaner in flight. The muffler is very close to the bottom of the fuselage, but an O.S. muffler extension, Part Number 25425600 will move the muffler another 0.437" away from the fuselage bottom.
I fuelproofed the tank compartment with clear polyurethane and installed the 10-ounce fuel tank before sheeting the top of the fuselage and the cowl area.
Sheeting of the nose section is a trip! The 1/8" soft balsa must be bent into compound curves to transition from the flat fuselage sides, over round formers, to the rounded cowl. I had reservations, but used a lot of water on the outside of the soft balsa sheeting and it worked. Thick CA, with accelerator, helps to glue the ends in place and the center will take care of itself. It was necessary to fill some gaps with slivers of scrap balsa that pulled open in the side seams. When it was dry, Hobbico Hobbylite Filler smoothed out the remaining irregularities very nicely. Addition of a small balsa fairing on top completes construction of the wing.
The wing hold-down block is shown in the wrong location on the plans and a supplemental sheet to correct the problem is included in the kit.
The landing gear is pre-bent from 0.125" music wire. I bound the joints and silver-soldered the wire in accordance with the instructions.
It was time for some bare bones photos and covering!
I picked Flat Cream MonoKote to simulate the natural fabric used in the early days of aviation. This was my first experience with a flat color MonoKote covering. I usually do a good job of covering with MonoKote, but the flat colors seem to work a little differently. It seems to be more difficult to shrink small wrinkles out of the flat colors than with regular MonoKote. Except for the wingtips, which will be discussed later, it was a relatively simple covering job. Nevertheless, it takes a lot of work to remove minor wrinkles that seem to appear here and there.
The oddly shaped wingtips presented unique problems. I first tried to cover a tip with a single piece of MonoKote. Bad idea! There was no way I could get rid of the wrinkles!
Covering each segment of the tip with an individual piece of MonoKote was the next option. This worked a lot better, but still wasn't as good as I would have liked. Another problem, at that point, is that if you only bought two rolls of the basic color MonoKote, you may run low on scraps big enough to cover everything, particularly if you blow something like the wingtips, and have to tear it off and start over. Be conservative with your covering material or you may have to go buy a third roll. Strangely, many of the remaining wrinkles disappeared after the plane sat for a few days!
A thinned-out coat of epoxy was used for fuelproofing the firewall and inside of the cowl. The area was finished with a coat of Flat Black LusterKote. A coat of clear polyurethane was used to fuelproof the wing saddles and other parts of the radio compartment that may be exposed to fuel or oil.
The landing gear comes pre-bent to shape and everything fits nicely. Soft wire is provided for binding and I used silver solder for the joints. The box photos show some kind of simulated wood struts on the landing gear, but there is no mention of them in the instructions or on the plans. Using some 1/4" x 3/8" balsa, I cut grooves for the wire using a Great Planes "Groove Tool." After carving and sanding the outside to an airfoil shape, I epoxied them to the wire landing gear legs and finished the whole assembly with Military Flat Earth LusterKote. Top Flite was due to have 4-3/8" wire wheels for the Elder, but they weren't available at the completion of this review. The instructions call for 3-3/4" wheels, but they look kind of small for the application. I substituted Williams Brothers' 4-3/8" vintage wheels. World War I aircraft generally used large wheels because they had to operate off rough fields much of the time.
I fly from a paved runway, so the fixed tail-skid was replaced with a steerable tail wheel to facilitate ground-handling. Hardware is provided for both installations.
The radio compartment is roomy and the servo tray is pre-cut to fit S3003 servos. The Elder balances perfectly with the battery and receiver between the servo tray and fuel tank.
A Futaba 6DA radio was used for this project. A servo tray is provided with cutouts that match Futaba S3003 servos exactly. Two 1/4" dia. wood dowels and 2-56 threaded rods are provided and the pushrods are easily assembled. As in most kits, plastic clevises are provided. I replaced all of them with Great Planes metal clevises. I finished the wooden dowels with Flat Clear LusterKote. The rest of the radio installation is straightforward and simple. Pushrods are not provided for the ailerons and must be purchased separately. The receiver and battery were wrapped with foam rubber and placed between the servo tray and fuel tank. A piece of 1/8" lite plywood, screwed to two pieces of 1/4" x 1/4" basswood, holds them in place.
Recommended throws are given in the instructions and are easily set up using the transmitter throw adjustment feature. A Robart Incidence Meter was used for checking wingtip and aileron alignment.
Top Flite's new wire wheels give the Elder the "finishing touch." They're lightweight and look great!
King Posts are part of the "scale" look in the photos on the box and in the instructions. No stock is provided and they aren't shown on the plans. They are shown in some of the photos in the instruction book and dimensions are given for cutting the lengths of 1/4" dowel. Beyond that, you're on your own in figuring out the angles and placement. They are purely cosmetic, so whatever looks good and misses the machine gun will work.
I finished them with Flat Clear LusterKote. The instructions recommend elastic thread, available from fabric stores, for the rigging on the wing and rear fuselage. Installation on the wing was no problem. It has no structural value and is cosmetic only. Since the Elder is to be used as an every-day flier, I omitted the rigging on the open framework of the aft fuselage. It would be a potential dirt and oil collector and would be very difficult to keep clean.
The Elder balanced perfectly, fore and aft, with no ballast required! One-half ounce of lead was added to the port wingtip for lateral balance.
My wife, Suzi, painted a 1/6th Williams Brothers' pilot to create "Sir Reginald." A 1/6th Williams Brothers' Vickers machine gun was added to complete the WWI effect. It was time for the static photographs.
To avoid any frustrating surprises at the field, I ran a tank of fuel through the O.S. at home. When trying to fuel up, I found that one of the vent lines was blocked. It turned out to be kinked between the tank and firewall. It was necessary to pull the engine to figure out the problem and correct it, but these things are much less annoying when discovered at home rather than at the field!
I enlisted Spirits of St. Louis R/C Flying Club member Don Fitch to take in-flight photos. The Elder's ground-handling characteristics are great, until the tail lifts. Then it turned to the right. There was a mild crosswind from that direction, which may have contributed to the problem. The tail moment is long and the fin large, which could cause weathervaning. When taking off directly into the wind, it lifts off quickly and climbs out smoothly. It handles like a well-designed trainer. It turns and loops easily. Thanks to the flat-bottomed wing, rolls require correction with the elevator to keep from yawing. It spins slowly and recovers easily. Landings are a piece of cake with some tendency to float. If you try to turn on the ground at too high a speed, it will tip over, thanks to the narrow tread of the wheels. The landing gear is well forward, so the prop is protected when it tips onto a wingtip. Taxiing back is very controllable. The large wheels allow flying in and out of reasonably cut grass fields.
Shortly after the initial Elder flight tests were completed, Top Flite introduced wire wheels for use on it and other similar sized vintage aircraft. They're absolutely beautiful! The hubs, rims, and spokes are chrome-plated and are exact replicas of full-size wire wheels. The tires have ribbed treads and appear to be replaceable. The hubs have 0.156" bores and can be brushed with 5/32" brass or aluminum tubing to fit the 0.125" axles on the Elder. They are 4" in diameter and weigh approximately 3 oz. each, almost exactly the same as the Williams Bros. 4-3/8" vintage wheels. On the pair I have, there is some run-out, but not enough to be a problem.
The Top Flite Elder 40 is a pleasure to build, finish, and fly. It's gentle enough for a novice flier, but is capable of modest aerobatics. The O.S. .46 FX has plenty of power for this application. A .52 to .70 4-stroke would also work well. Take-offs can be a little dicey in the beginning, but can be dealt with once you know what to expect. Addition of the wire wheels make the Elder look even better! Think of it as a trainer with a personality. I plan to use it for relaxing, everyday flying and as a trainer for my grandson, Alex.
Flight Photos by Don Fitch. Reprinted with permission.
May, 2003 R/C Modeler Magazine
Editor: Patricia Crews