Please be patient while all of the large photos load- I wanted to offer everyone a good look at this design, and a few more photos of the plane in the air at the KING and LOOKOUT POINT slope flying sites. I hope you enjoy all of them!
The photos and information below offer a good look at an incredible flying aircraft!
Wingspan : 60" EPP foam, .230 tubular Carbon Fiber spar on top surface
Wing Chord : 10.25" center, tapered to 8.25" at wing tips
Wing Area : 555 square inches = 3.85 square feet
Wing Layout" 3" Dihedral at one wing tip, with other half of wing horizontal; Full Strip Ailerons 1.5" wide
Fuselage Overall Length : 38"
Controls: Ailerons and Elevator; Dual Aileron servos allow Spoileron deployment for landing
Flying Weight , E-Powered: 48-3/8 Ounces with 05 Cobalt brushed motor, 7 cell GP 2200 NiMH battery pack installed; (up to 53-1/2 ounces when flying with the 7 cell Sub-C battery pack.)
Minimum Flying Weight, Sloper configuration: 32 Ounces, when built with 3 each HS-81 servos
Wing Loading : 12.5 to 13.9 ounces per square foot (E-powered) , depending upon battery pack used
Sloper Configuration minimum wing loading: 8.33 Ounces per square foot; ballast can be added in the battery compatrment. In heavier winds on the slopes, it flies well at 12.5 Oz./Sq. Ft., in the E-powered configuration with the large battery installed
Motor : 05 sized Cobalt (Brushed) motor, 6 turn : MAXX PRODUCTS / MPI 0506 (No longer available; everything is going to brushless these days!!)
Propeller : Graupner CAM 9x5 folding prop, or Freudenthaller 9.5x5 prob blades in vented spinner (as flown at 10,000 feet ASL) from HOBBY LOBBY
Battery: Favorite = 7 cell GP 4/5 Sub-C 2200mAH NiMH pack @ 11-7/8 ounces; I also fly two other pack sizes: 7 cell GP 3300 mAH NiMH @ ~16 Ounces; and 7 cell GP 3700 mAH NiMH @ 17 Ounces. The newer GP 2200 4/5 Sub-C cells are definitely an ideal compromize in weight and capacity / duration.] The GP cells are available as loose cells or custom built battery packs from CheapBatteryPacks.com (Other newer Sub-C NiMH cells of even higher capacity and better performance under load are now available from them.)
Speed Control : in January 2006, I'm now flying my VIKING 60 with a Castle Creations PEGASUS 35 ESC mounted on the under side of the motor mount, inside the nose cowling in the airflow for good cooling. (About $43.00 from various sources)
Radio System used: Airtronics RD8000 Super Transmitter; GWS 8 Channel Dual Conversion Receiver; three Hitec HS-81 MG servos
Since it's built entirely of the very resilient EPP foam with Coroplast tail members, it can fly and land *Anywhere* without sustaining noticeable damage, even with rough landing conditions at rocky or sage brush covered sites. The propeller and spinner are the most vulnerable aspect of this design, and when set up with a folding prop, it should hold up very well in most reasonable landing conditions. A folding prop is definitely appropriate! It's likely most suceptible to taking some damage when engaged in 'Powered Slope Soaring", when landing on rocky landing sites. We fly some of those up here in the Colorado Rockies!
The wing on this one is detachable, mounted to the fuselage with 4 #8 pan head sheet metal screws running through 1/32" ply plates & balsa filler blocks in the wing, which then fasten into 1/8" birch ply plates that are epoxied into the EPP foam. Nylon filament tape wraps the fuselage to complete the securing of the wing mount plates. (In building my own EPP aircraft, I prefer to work with epoxy, which outgasses less volatiles, as I am personally sensitive to solvent based glues; others use GOOP and a variety of other adhesives.)
I'v worked on many E-powered designs over the past 20 years. One of the details that can be elusive is to get the motor incidence "just right", so that there is no trim change between full power on, and power off / glide modes. I've managed to get it as close to perfect as I expect is possible on the VIKING 60! - no playing with the trims when cutting the power and working the wind!
Glide? You bet! The SD6060 is an ideal airfoil for this design; it's one of the top slope soaring airfoils in use, and is very suitable as well for E-Powered aerobatic flight. It is the one I chose for the desired performance envelope of the VIKING 60. It's definitely performing to & beyond the best of my expectations. And besides handling smoothly in heavy and gusty winds, the glide in light air is great, too.
Bad Habits? Well, we haven't noticed any so far- and the test flying to date flying the E-power configuration and the sloper configuration, has been in a variety of conditions, including slope winds gusting to 45 MPH on the Dwyer wind speed meter. It's definitely what I'd hoped to accomplish, and more.
A few more details: I cut the wing cores for the VIKING 60 from 1.3 pound density EPP foam, using the SD6060 airfoil for this wing. I used a band saw to do the 1.3 pound density EPP foam fuselage's major shaping, before going to the fillet knife & sanding blocks to complete the final shaping.
The 4 cell 1500 NiCad (A sized cells) Panasonic receiver pack in the sloper nose contributes some substantial weight, just where it's needed, well forward in this nose section. There's presently 4-1/8 ounces of balancing weight, in the form of ten sheets of 1/16" thick lead, in a compartment just behind the battery in this sloper nose. Flying weight (sloper configuration) is at a minimum of 32 ounces- a good weight for slope soaring with this size aircraft in light winds, giving it a wing loading of 8-1/3 Ounces per square foot for this 3.85 square foot wing. Ballast weight for flying heavier winds is quickly and easily velcroed in place under the canopy in the battery carrrying compartment (which is located over the CG for easy balance adjustment.)
For flying with the 05 Cobalt motor, the sloper nose comes off, and the motor mount attaches quickly to the firewall with 4 screws. (I'm now using a Dave Brown 2025L motor mount, which weighs about 1 ounce.) Performance with this motor / battery setup is quite impressive at the 48-3/8 ounce flying weight.
The firewall is made form 1/8" birch aircraft plywood which is epoxied in place, then 'pinned' with 6 each 1/8" hardwood dowels which are epoxied 2" into the EPP foam behind the firewall on the top and bottom. This is a good way to anchor the firewall deeply into the EPP foam. [Tech note: there is a 4 degree motor downthrust angle used on the Viking 60; cutting the foam to this angle before mounting the ply motor mount firewall is my preferred method of achieving this angle.]
The black EPP foam cockpit canopy hinges forward, giving access to the place for the 7 cell battery, or for ballast weight when slope flying. (The canopy is vented to offer a bit of battery cooling when flying powered aerobatics; the rear end simply tapes down in place.)
Flying weight for the E-powered version ranges from about 48 ounces when flying with the lighter 7 cell GP 2200 MaH NiMH battery pack, to 53-1/2 ounces with the large 7 cell GP 3700 mAH NiMH battery installed , for an available power loading of up to about 100 watts per pound- plenty (depending upon prop chosen) for aggressive aerobatic capability!
I built this VIKING 60 with 3 of the HITEC HS-81 MG servos, and one of the GWS 8 channel dual conversion receivers; one servo for the elevator, and two used for the ailerons, so that they could be deployed as "spoilerons' to dramaticly slow down this sleek plane for landing in smaller areas. This has already worked very well on the Viento. The aileron servos are buried in the wing, covered mostly by the fuselage, with the linkages running closel along the sides of the fuselage, where they are least vulnerable to damage in slope combat action.
I installed the Coroplast vertical and horizontal stabilizers with 6 minute epoxy, as well as the carbon fiber tubular spars in the wing. The Horizontal stabilizer has a !/8" O.D. carbon fiber tube stiffener slid into the coroplast just in front of the hinge line (Epoxy bonds well to the EPP foam, sets / cures quickly, and stops out-gassing quickly- something I prefer to use rather than GOOP, etc.) I did spray down the EPP foam with 3M Super 77 spray before covering with the colored packaging tape.
The "VIKING 72" is a larger version of the VIKING 60, with 705 square inches of flying wing surface area, with a minimum flying weight (for this one as set up) at 46 Ounces. This results in a minimum wing loading of 9.4 Ounces per square foot for light lift days. There is a ballast compartment centered just over the wing spar that can hold over 32 ounces of ballast weight if desired, to bring the wing loading up above 15 ounces per square foot on the high wind days.
It is set up to fly with a standard sized Airtronics 7 channel radio receiver, and a full sized Dymond Metal Gear servo for the elevator. Both of these are installed in the forwward fuselage, not far behind the battery pack. I used a Sullivan Carbon Fiber control rod for the elevator in a straight-line run. It's installed with the control horn on top of the elevator, so the servo is *pulling* to bring the plane up out of a high speed dive. Two HITEC HS81 Metal Gear servos are instaled in the wing for the ailerons. This sloper is also being flown on an Airtronics "RD8000 Super" transmitter, with Spoileron control setup on the two aileron servos in order to slow the aircraft for landings.
Considering that this long sailplane would need a fair amount of weight up front to counterbalance the long tail, I built a 4 Sub-C cell Panasonic 1500mAH NiCad receiver battery pack to install in the nose, then used about 5 ounces of lead to arrive at the correct balance.
The leading edge and underside of the VIKING 72 wing are covered with Flourescent Orange for high visibility and good definition in the air.
Kits are not available for the VIKING 72)
Above is Mark Stewart flying his VIKING 60 on the slope at LOOKOUT POINT on May 31st, 2004. He flew his first flights on KING the day before, and emailed me the following brief comments on the following morning:
"Yesterday the wind was ripping. New viking is a treat. Great plane. Well done Bruce! [Mark Stewart]
Color Photo illustrated instruction booklet, including instructions for completing the E-Power setup.
Precision Cut EPP Foam Wing cores
Tubular Carbon Fiber Spars with Aluminum Joiners
Band Saw Cut EPP Foam Fuselage; Slotted for Horizontal & Vertical Stabilizers, with the rear fuselage sides pre- tapered
2mm (Optional 4mm) COROPLAST Vertical & Horizontal Tail Surface Material, with extra material for radio system hatch covers
5 feet of 1/8" diameter clear plastic tubing, optionally used to smooth the leading edges of the 4mm Coroplast tail surfaces; simply tape in place
Triangular Sub-Trailing edge material & selected 1/4" x 1-1/2" Balsa Aileron stock; makes top-surface aileron hinging with tape quick & easy!
All wood materials included to complete the detachable wing version construction
WHAT YOU NEED TO SUPPLY TO COMPLETE:
Your Hand tools for cutting, drilling, shaping, and sanding, plus these materials:
Radio System with 3 servos; HS81 MG servos recommended as minimum, or equivalent. Transmitter with Spoileron activation capability highly recommended!
Your choice of elevator control rod, aileron control linkages, and control horns; (everyone has their own preferences for these items!)
(I will report that, from my testing, the Du-Bro Lazer Rods seem to shrink / stretch less with temperature variations than the other plastic control rods which I tested.)
Nylon Filament Tape, 3M 77 spray adhesive, your choice of covering material, and either 6 Minute Epoxy, or your preferred choice of EPP Foam- compatible adhesive, (such as GOOP)
Scotch 3/4" wide "Multi-Purpose' tape for aileron hinging
You can cover the VIKING 60 using a low temperature iron-on covering material such as Ultracote or Oracover; keep in mind that the Nylon filament tape on the fuselage is what gives the Viking 60 it's major strength and durability for slope combat flying- make sure you apply a complete layer of it to the entire fuselage!!
You can check on the availability of a VIKING 60 kit on this page; if I post a notice that kits are once again available, please check stock by first emailing firstname.lastname@example.org or calling 719-836-2489 to check the current availability status, then mailing a check or money order to Bruce Stenulson, P.O. Box 69, Fairplay, CO 80440. (I'm not set up to accept credit cards or Paypal payments funded from credit cards, but if you have a PayPal account funded from your bank account, you can make a payment to me that way. (For shipping costs, please check this page, or email me for a quote; prices have increased dramaticly from what was once possible.)