The Highlanders

Above, the HIGHLANDER XXL on it's floats after a brief session flying form new snow on 12-31-2021. Note the float mount gear, which has the 'spreader' cross-brace wires installed. It is handling nicely in challenging wind conditions. With the enlarged vertical stabilizer and longer tail moment of this XXL version, it has the tail group authority to handle (= stabilize) the added forward side area of these floats with no problems.


3 scratch-built Highlander variant bush plane fuselages, 3 different KFm3 variant wings

One fuselage and one wing built from Depron foam sheets in 6mm and 3mm thickness

Two fuselages and two wings built from DOW Bluecor P/P EPS Foam in 6mm Thickness

This Page Last Updated on January 22nd, 2022; Thanks For Visiting

Most Recent Major Update: Float building and setup for the Highlander XXL   last updated on 12-24-2021

This page was updated with completion of the HIGHLANDER XXL Fuselage Build and Revised Plans With Floats on December 20th, 2021

This page was updated with the HIGHLANDER XL stretched fuselage build details and photos on November 14th, 2021

This page was updated with a new 44" span KFm3p Shaped Airfoil wing build for the HIGHLANDER XL fuselage on Nov 27, 2021

This page was updated with wing incidence reduction modification and landing gear stiffening details for the first fuselage on October 2nd, 2021 - thanks for visiting!

Above: my January 2021 build of the 'Just Aircraft' HIGHLANDER, a variant inspired by Thomas B's plans for the Buschtrottel which were published in the German 'Modelflug' magazine

My build features a shaped airfoil KFm3 variant wing, full wing tip plates, Slats on the wing's leading edge, horizontal stabilizer tip plates, and airflow fences on the separating line between the flaps and ailerons. The removable wing has four 5 gram servos to control the ailerons and flaps. The elevator and rudder are controlled with 9 gram servos.

Above: this is a view of the "Viking Highlander" build before the wing's leading edge slats were added; it sits high on 4" diameter tundra tires.

This is one of the more recent custom builds of the LSA Highlander sold as a kit by Just Aircraft; it features wing tip plates, horizontal stabilizer tip plates, and the airflow fences on the upper wing surface.

Plans with some english labels are available in the Buschtrottel thread on RC Groups; CLICK HERE


Wingspan: 35 5/8"
Wing Chord:8 3/4"
Wing Area: 310 square inches = 2.15 square feet
Overall length: 31"
6mm White and Black Depron and 3mm black Depron used in this build
Motors Used : Grayson Hobbies GH2212-10 (52g, 180 watts)   or Emax CF2812 (39g, 140 watts))
Propellers used: APC Slow Flyer 9"x3.8", 8"x3.8"
Battery : 3S LiPo 1000mAH preferred; 3S 1300mAH optional
ESC: 18 Amp to 20 Amp
Radio Receiver: 6 channel
Wheels : [Banggood] 4.00 inch @ 32 grams each; [Hobby King] 3" foam wheels @ 13 grams each; or hand-crafted 4" light foam wheels
Optional: 1/32" 3 ply Birch Aircraft ply skis 2.5" x 8", 16 grams each
Landing Gear: .062" music wire with 2mm CF rod doublers, heat shrink covered & CyA glue bonded
Flying Weight as built with 3S 1300mAH battery, on 4" wheels: 19-3/4 ounces; Wing loading of 9.2 Oz / Sq Ft


KFm3 Variant Shaped Airfoil Wing Building

I cut wing, fuselage, and tail group panels as laid out on Thomas B's plans. From there, I added internal wing structure as shown below, adding the black 3mm depron panel which forms the secondary step, and adding a 1/2" wide 6mm thick strip at 30% of chord to support the high point of the forward airfoil's curvature. The upper panel was rolled on a 3.3" O.D. cardboard shipping tube to get the desired curvature. It was then tape hinged in place to the leading edge. 6 minute epoxy was applied to the three contact areas, and the wing was folded closed into the airfoil shape and weighted down thoroughly with many 1/2 pound lead weights to keep it in shape while the epoxy set.

Below is an end view of the wing structure after glueing.

Below is a top view of the wing structure; full length ailerons / flaperons had been cut and tape-hinged before the glueing was done.

BELOW is a sheet of the templates I made and used to complete this build; it is 8.5" x 11"at 300 DPI. If you right click on it, select "save as", and then print it out, you'll have what I developed & worked with. No, it's not a fancy cad document, it's a full size scan. I hope you find this useful.
The wing top surface airflow fence template matches the curvature of the top surface of my KFm3 wing build; adjust to fit your build.

Below: wing tip plates now epoxied in place, leading edge shaped, sanded, heat-formed. I then ironed on a 3" wide piece of 1.7 mil clear document laminating film wrapping over the wing's leading
edge; about 2" on top and 1" on the underside of the shaped leading edge. I also decided to set up the wing for separate flaps (9" long) and ailerons (7" long).

Below is a view of the underside oh the wing, showing the control horns , 5 gram servos, and linkages. servos were inset into the wing structure where the aileron servo extension
wires could be routed internally just behind the wing's high point internal spacer. A cutout on center allows the wires to be brought out to go to the radio receiver which mounts inside the fuselage just under the wing. The two aileron servos' wires  were combined into a single plug, soldered & heat shrink covered. servo wires from the two flap servos were also combined into a single plug.

I added .080 Carbon Fiber rods to the leading and trailing edges of the wing where the rubber bands would hold down the wing; the leading edge piece is 7" long. These were added before the laminating film was ironed over the leading edge. I then also ironed on laminatine film in the trailing edge area from the secondary KF step back, wrapping the entire area top and  bottom to further strengthen this area of the wing.

I added extra structure inside the fuselage at the leading and trailing edges of the fuselage to facilitate adding the wing mounts. 1/32" 3 ply birch aircraft plywood in then glued to the outsides of the fuselage, and .1" diameter bamboo dowels are passed through drilled holes. This allows mounting the removable wing with four #32 rubber bands. An additional former was also added inside the fuselage to support the rear end of the battery carrying tray /  plate.

Below: Gluing the tail group in place after verifying that is everything is aligned correctly.

The Buschtrottel plans by Thomas B show two pieces of 1/16" diameter music wire, so I cut them , then bent the legs of the second piece to join the main gear legs as shown. I then wrapped these joints with kevlar fly tying thread and coated the wraps with thin CyA glue. I then cut a piece of 6mm black Depron to fit the inside of the wire, and glued it solidly in place with hot melt glue . I then decided in a gear location; I wanted the landing gear legs directly below the leading edge of the wing. I then added in another white 6mm Depron vertical support for the landing gear's front edge location.

Below is a view of the underside of the fuselage; the 6mm black depron was glued in place, and a section of velcro was added for the landing gear mounting.The motor is mounted, waiting to be connected. I chose an APC 9x3.8 slow flyer propeller for early flights.

BELOW: The elevator has a section of .080" solod CF rod as the center joiner; this was installed before bevel cutting and tape-hinging the elevator to the horizontal stabilizer. The rudder was also bevel-cut and tape hinged to the vertical stabilizer before the tail group members were assembled to the rear end of the fuselage.

9 gram servos are used for the elevator and rudder control, cut into the rear fuselage top deck as seen in the photo below. control horns are made from 1/32" 3 ply birch aircraft ply. I prefer to use EZ-connectors on the control horns. since servo horn holes match .040 music wire, the ends of the .080 CF control rods are made from that size music wire; the metal ends are then wrapped in place with kevlar thread, with the wraps then being coated with thin CyA glue.

Below is a view of the rudder control rod and horn installation.

I did the window & door graphics with hand-cut colored (2.2 mil?) packaging tape. Since tape doesn't bond very well to bare Depron, I used 1.7 mil iron-on CP document laminating film to overlay a clear base surface to which the colored tape could bond solidly. I ironed on the clear film from the from edges of the nose of the fuselage back to the wing's leading edge on the upper surface, back on both sides to about 2" behind the doors, and back on the bottom surface to the landing gear velcro mount area. (This bottom skin provided a tough surface to which the ESC could be mounted with a bit of hot melt glue.)

I save the backing sheets from other letter-size adhesive laminating film as a working surface; on one full ~9" x 12" sheet, I covered it with the blue colored tape with fairly narrow overlaps; this gave me a solid blue sheet of the blue tape from which to cut the doors & front window using the templates. Once the window & doors were applied to the fuselage, I laid out the black tape on another backing sheet, and cut the narrow strips to create all of the black outlining.

 4" wheels are held on the axles with short sections of wire insulation.

Below; The area for the ESC mounting was first overlaid with laminating film; then the wiring was completed, and the ESC mounted in place with hot melt glue.

Below is the view of the Battery access door, which was bevel-cut in the side of the fuselage, and tape-hinged; a 3S 1300mAH battery is shown in it's mounting position.

Below: Airflow fences were added to the upper wing surface aligned with the flap/aileron junction.

HIGHLANDER with skis mounted.

Below is z\a closer look at the ski mounting details. To keep them in place with a slightly nose-up attitude during normal flight, torque rods are used. Start with !/6" plated brass wheel collars; drill a .040 hole, cut and bend a piece of .040 music wire to suit you build, and solder the music wire into the wheel collar using 2% silver solder.

  I pulled out a set of lightweight skis with a fair amount of surface area and mounted them in place of the tundra tires. Each ski weighs 1/2 ounce less than the tire it replaces.

I make lightweight skis from 1/32" 3 ply birch plywood.These skis are 8" long by 2-1/2" wide; once cut to shape, the nose end is submerged in boiling water; depth of water is only enough for the area you want to bend. It doesn't take long for 1/32" birch aircraft ply to become flexible, so do one ski at a time, testing the flex until it's pliable enough to curve nicely, then get it out of the water. weight down the main flat ski body withe a HEAVY weight with the ski's tip blocked up to the desired height, and let it dry thoroughly.
The lengthwise spine is cut from 1/8" 3 ply poplar 'lite ply' .
 Laminating film is ironed on the bottom surface for slickness; a bamboo toothpick, flattened on one side, is glued on as a tracking keel strip.

BELOW: The slats have been cut and rolled, then heat formed into shape. They were then covered with laminating film before mounting. I made spacers for iether end, and also added a support at the front end of the airflow fences. These slats are permanently installed witth hot melt glue.

BELOW: In mid-January of 2022, I re-installed the slats on my first ~35" span Depron wing. they now extend forward and down below the leading edge of the wing about 1/8",

and the spacing between the slat and the wing surface narrows towards the trailing edge of the slat.


Flap deflection while in-flight results in a nose-up movement; without using FLAP > ELEVATOR mixing, this makes the aircraft close to unmanageable!
I've now set my 1/2 flap switch position result in a drop of 15/16". I temporarily have full down flaps set at 1-3/8". My mixing setting is presently at -79% on my Airtronics RD8000 transmitter.

(Note: UPDATE:  later changes to the wing's flap setup, as seen in the last photo above, with the fixed center panel between the inboard ends of the flaps require far less Flap > Elavator mixing.)


Is too much + wing incidence hurting the power off glide?

Quote: Originally Posted by bisco

 " I gave up on the motor i was using and put two latex tube rings on. that worked well and i had a good flight, but this bird is very twitchy from side to side. i have the ailerons down to very small movement, and even with a large amount of expo, the smallest input makes her want to roll.

  "I don't know if it's the build or the pilot. i can fly her fast no problem, but when i ease up on the throttle, she drops like a rock, even with half or full flaps. nothing like thomas b."

Getting the Buschtrottel to do a clean and stable power off glide to landing is challenging- even more so in the 71% air density up here in Colorado's South Park. I've taken a closer look at this characteristic recently, and there's one detail that stands out which may deserve some attention and modification.

My build , done carefully from the plans in 6mm Depron, has 4.7 degrees of positive wing incidence for the wing's bottom surface relative to the horizontal stabilizer. (That's having the L.E. of the wing's bottom surface at 1/2" high, relative to the trailing edge, compared to the horizontal stabilizer's datum line..... With the airfoil- shaping of the leading edge of a KFm2 or KFm3 wing, the effective positive incidence of the wing is likely more than that. The difference between full-power-on level flight trim, and the power off trim required for gliding a wing with that much positive incidence is very substantial.

Based on my development & test flying of the early DANCER KFm2 wings, as well as tuning work on hand launch gliders as well as a wide variety of balsa and foamie aircraft- powered & non-powered slope ships, etc.- over the last ~38 years, I'm beginning to suspect that this aircraft will perform far more predictably in a power-off glide landing approach if it is built with a LOT less positive wing incidence.

(For reference, the Dancer I with it's KFm2 wing glided best in power-off mode when the wing incidence was in the +1.3 to +1.5 degree incidence range, relative to the horizontal stabilizer. Best flight performance was achieved with the balance at roughly 41% of chord- KFm2 upper layer's back edge was at 50% of chord. PHOTOS of this design example below. )

So my experimental approach will be to begin to block up the wing's trailing edge by about 3/8" to remove a lot of the extra positive incidence, then go test fly it in South Park's thin air.

You're possibly thinking, "what about the drag moment of those monstrous wheels, producing a nose-down pitching moment that needs to be counteracted?" Good Thought! So I'll also fly it with medium width 3" wheels to start while playing with the wing incidence, and then test fly it with some narrow 2.5" wheels, and with wide 100mm wheels, and thereby try to get an answer on the magnitude of that possible pitching drag factor...

Reduction of positive wing incidence helps flight performance

Before doing the wing incidence test flying, I stripped the LE Slats from my wing and installed new airflow fences between the flaps and ailerons, as seen in the photos below.

I next installed a 3/8" thick shim block under the trailing edge of my (removable) wing as shown in the photos, and went out to test fly the Highlander variant this afternoon. I also mounted narrow 2.5" wheels for the first test flights. ( Balance was set at about 40.2% of chord; this is 3.5" back on this 8.7" chord wing.)

The first thing was to get the power-off, no flaps elevator trim set for a good no-power glide to landing approach. Once that trim setting was set, I added in Throttle > Elevator mixing so that the aircraft would climb modestly but would not balloon when using higher throttle settings. This particular shaped airfoil KFm3 variant wing needed a fair amount of this mixing to maintain fairly level flight throughout the throttle range. My interpretation was that the wing incidence angle was still too much to the positive.

Next, I added first one more 1/16" shim under the wing's trailing edge, test fly, and then a added a second one, ending up with 1/2" of balsa shim under the wing's trailing edge. This was enough to remove most of the 4.7 degrees of positive wing incidence as mentioned in the previous post. (My wing build's shaped KFm3 airfoil still has effective dynamic positive incidence even with the wing's bottom surface now set parallel to the horizontal stabilizer)

Above: Added black depron wedges to close the air gap. I ended up with a 1/2" square balsa block under the wing's trailing edge. The result shown in test flying after the increased shimming was that substantially less throttle > elevator trim was needed to fly the full throttle range from full power to power-off glide. ( For my particular wing's airfoil, an additional 1/16" of shim might further reduce the throttle > elevator mixing setting to even closer to zero.)

With this much established, I started test flying with the flaps added in. My initial observation was that less flap>elevator mixing was required to fly with flaps deployed , and the aircraft behaved far better on a full flaps, no power glide approach to landing.

Changing from the 2.5" wheels back to the 4" wheels, and re-balancing to the ~40% of chord again, showed that the aircraft continued to have far better no-power glide to landing characteristics with the reduced wing incidence; there's not much as far as any noticeable drag affects when flying with the larger wheels, so that's a very minor issue.

I hope this test report helps some of you- I know that my aircraft now handles more predictably, with a good no-power glide. I'll be continuing to play with the flaps & their mixing settings to further fine-tune the performance.

UPDATE: This is still an ongoing experiment at this time. I'll likely leave off the slats; on my build, and flying in the 71% density air here in South Park CO, the wing seems to respond to control input more cleanly without them...


Landing Gear Stiffeners

When I built my Highlander variant of the Buschtrottel, I used 1/16" music wire or my landing gear- didn't have any 5/64" or 2mm on hand. I find that this wire gear is not as stiff as I would like for this weight of aircraft.

Rather than totally replacing the landing gear, I decided to add some 3mm CF rod as doublers / stiffeners, added to the existing gear legs. I used two sizes of heat shrink tubing, some a bit larger for over the lower gear joint, and the smaller size for the main section of each gear leg. The CF rods extend from the aircraft's belly out to where the bend to the wheel axle section. (Photo below.) After the heat shrink tubing was shrunk in place, I wicked in several drops of thin CyA glue to bond the assembly internally. I then added some hot melt glue on the ends touching the aircraft's belly.

The result is much stiffer gear legs; these should do nicely!

I'm flying at 17-1/4 ounces with a 3S 1000 battery and the lighter weight 3" foam wheels.


Testing Another Wing on the Highlander: Reduced Wing Loading

The air is thinner up here at 10,000 ft. ASL in South Park; it's only 71% of the density of air close to sea level.

The wing loading on my KFm3 variant build of the Highlander is at 9.2 ounces per square foot. In order for an aircraft to fly at a slower airspeed, the wing loading has to be reduced.

My slowest flying conventional layout aircraft are built light, with single surface under-camber wings.

On my WOODSTOK float plane, I'd designed & flew an under-cambered single surface flat-built wing with ailerons; that wing was quite light weight, and performed very well.

So I decided to design a new wing that would mount on the Highlander fuselage, with more wing area and less weight. The photos below show the result.

This wing is made from DOW Bluecor P/P; span is 39.5", chord including ailerons is 10.5" for 2.85 square feet of wing area. Wingtip plates are made from black 3mm thick Depron, covered with 1.7 mil Doculam CP iron-on laminating film. There is a .080 diameter solid CF rod along the entire leading edge of the wing. A 17" long piece of the same material is also inset along the upper trailing edge.
One HXT900 9 gram servo is built in at the center of the wing, with .040 music wire control rods going out to the EZ-conectors on the aileron control horns (which are made from 1/32" 3 ply birch aircraft plywood.)

This wing has a span of 39.5", and a total averaged chord of 10.5", including the 2" wide ailerons, for 2.85 square feet of wing area; and it's 2 ounces lighter than the KFm3 variant wing.

By switching from the 32 gram 4" wheels to a set of 13 gram 3" wheels, I dropped another 38 grams of weight. Then I installed a 1/2 ounce lighter 3S 1000mAH battery.

With the wing area increase and the flying weight dropped down to 16 ounces, I've ended up with a wing loading that dropped from 9.2 ounces per square foot down to 5.6 ounces per square foot... the difference in slow flight capability in this thin air up here should be fairly dramatic!

Winds are gusting somewhere in the twenties today- a better building day than flying day. When I get a chance to get back to test flying, I'll fine-tune the wing incidence; I already have the wing's trailing edge raised 6mm, and for this type of airfoil, it may need to have it's trailing edge raised even more [compared to the Buschtrottel plans' stock wing incidence for the flat built KFm2 wing.]

1-31-2021 Update: Winds died down during the night, and it warmed up to about 17 F by 10:30 AM, so I headed to my test flight spot- the Helipad.

I pulled out a 3S 950mAH Nano-Tech battery which is lighter weight yet ( at 2.55 ounces), bringing the flying weight down to 15-3/8 ounces for a wing loading of 5.34 Oz. per square foot.

SEE PHOTO ABOVE: With the 6mm thick Depron shim added under the wing's trailing edge (to lower the wing incidence relative to the horizontal stabilizer), this under-cambered wing is happier with the wing incidence. (The shim structure is tack-glued to the T.E. of this wing itself, making swaps between the two wings simple & quick.) Further experimentation is called for; this setup does nor handle well at high power levels. [Further wing incidence modification may be called for.]

It took off nicely, and flew well. Being under-cambered, this wing wants to fly right-side-up; it's not designed for aerobatics, but turns well with the ailerons. Mixing aileron into rudder should optimize the turning capabilities. It flat spins nicely in a tight gradual downward spiral, loops well, but really isn't meant for inverted flight.

A cool breeze came up; coming in low & slow into this modest breeze, the aircraft slows down to walking speed or below, and is still responsive to the control inputs. It was almost slowed down on forward ground speed to doing a helicopter touchdown- (no flaps needed on this wing). This under-cambered wing really is capable of very slow landings, yet still handles higher speed flight fairly well. For windier conditions & more aerobatic flight, I'll just swap back to the KFm3 wing. (I may fly the lighter battery & lighter wheels more of the time.)


Highlander XL Fuselage design & Build Nov. 2021

I decided to design a new Highlander Fuselage, incorporating several changes from the previous build. Later models of Just Aircraft's Super STOL XL featured a stretched aft fuselage; I decided to incorporate this into the new design, designating it the Highlander XL. With the horizontal stabilizer mounted as shown, The tail moment is extended 1-3/8"; further lengthening can be done if desired.


Longer Fuselage = ~28" long fuselage side panels, 2-3/4" wide fuselage : 34" overall length as built out. ( I used DOW BLUECOR P/P for this build, which is 1/4" thick)

Lighter weight 39 gram 140 watt motor;

An EMAX CF2812 motor is turning an APC 8x3.8 slow flyer prop with a 3S 1000 mAH battery.

Designed for removable / Interchangeable wings; wing mount area at zero degrees incidence to the horizontal stabilizer

Landing Gear mount plate in fuselage belly and added cross-members; new landing gear with screws to mount it & ultralight foam 4" wheels

 Redesigned counter-balanced elevator, horizontal stabilizer ends with added airflow fences

4 servo wing is built with a KFm3 variant shaped airfoil profile; Flying weight with this wing is at 16 ounces

Hand cut tape trim  and separated wing and aileron end plates as seen below were completed on 11-13-2021

Below is a photo of the HIGHLANDER XL with the 2.85 square foot under-cambered slow flyer wing mounted; 14-3/8 ounces flying weight for 5.04 ounces per sq. ft. wing loading

The wheels were made from very light weight "Aqua-rider" foam, with 1/32" birch ply plates glued on either side where the 1/16" axle passes through. They are retained on the axles with pieces of wire insulation which is a snug fit.

The rectangular fuselage formers at the wing's leading and trailing edges are 2-1/4" wide by 5-1/4" and 4-1/4" high, with a 1-5/8" wide cutout in their centers where the battery support  deck passes through. The plan below was a rough working plan for the side panels; the landing gear mount area on the fuselage belly ended up being made from a single layer of 1/8" balsa overlaid with a panel of 1/8" poplar lite ply. The motor mount bulkhead is a 1-5/8" square piece of 1/8" thick birch aircraft plywood with a foam backer panel

Below: Rudder and Vertical Stabilizer plan drawn on 1/4" grid graph paper

Below is a plan for the counter-balanced elevator; note gaps for the airflow fences on the ends of the horizontal stabilizer

Below: the left fuselage side panel has the battery access door cut away, then hinged in place at the front edge with clear tape. It will be held closed with tape too. The area where the closure tape is used has been overlaid with clear document laminating film to keep the tape solidly attached without damaging the foam's surface.

Below also is the horizontal stabilizer and elevator. A 3mm CF rod joiner / stiffener is inset across the elevator. two pieces of 1mm x 4mm CF flat strip are inset in the foam 3/8" in from the outer edges of the elevator's counter-balance panels to reinforce and stiffen them. Slots for the airflow fences to attach to the outer ends of the horizontal stabilizer are cut; the elevator is tape-hinged to the stabilizer.
(BELOW: This the first XL cutout and  build, with only 1-3/8" stretch to the tail moment; the plans above give 2" of tail moment stretch.)

Below is a view of the interior formers from the bottom of the fuselage, with the battery support deck in place; the other three foam lower cross-members were cut to fit and glued in place. The 2-3/4" wide landing gear mounting plate runs from the former at the wing's leading edge , back 1-5/8".

3/32" bamboo dowels are used for wing hold downs for use with #32 rubber bands; they are glued to the formers and fuselage side panels

Below- gluing the rear lower fuelage belly panel in place; I used 6 minute epoxy. A 1/4" thick foam temporary spacer is clamped between the aft ends of the fuselage side panels during this gluing step to provide a place for the lower extension piece of the vertical stabilizer to be inserted and glued later.

The horizontal stabilizer mounting area has a triangular cross-member glued in place; surface has been 'wood-peckered' with a pin to allow the 6 minute epoxy to penetrate through the thin plastic surface film of the Bluecor foam for a stronger bond.

Below: the vertical stabilizer and rudder are tape- hinged together; a temporary 1/4" spacer was used to set the spacing for hinging the lower rudder support section in place.  This piece which inserts between the aft ends of the fuselage side panels was later shortened so that it extends in 1/2" between the aft ends of the fuselage side panels

Below- horizontal stabilizer being epoxied in place

Below: next step, to glue the vertical stabilizer with it's attached rudder in place; note the lower support piece is trimmed to final shape

Below: vertical stabilizer epoxied in place, with 90 degree alignment support temporarily taped in place while the epoxy sets

Below: view of the completed fuselage's under-side. The panel just in front of the landing gear mounting deck extending about half way to the nose is removable, taped in place; the motor's ESC will mount on it's surface in the airflow. I use 1/4" x 1/2" balsa cross pieces as hard points under the motor mount area at the fuselage, and at the trailing edge of the wing. The wing's aft hold down dowel is located just behind the former at the art edge of the wing mount area. glued solidly to the former and to the fuselage side panels on the interior of the fuselage.

Below: ESC attached in place to the removable hatch panel with wiring routed inside.

The landing gear is formed from 1/16" music wire; before the final bends at the inner ends of the axle sections, I add a 3mm CF rod doubler / stiffener to each of the down leg sections, which are covered with heat shrink tubing. once the tubing is shrunk snugly in place and the final bends are made, I wick in thin CyA glue to bond the wire legs and the CF stiffener rods together. The mounting section of the landing gear is mounted to the lite ply gear mount plate with small flanged head servo mount screws, placed as shown. when all screws are snugged down, I wick in thin CyA glue along the wire gear and at each screw to lock the screws in the poplar plywood. This strengthens the landing gear installation nicely, with a minimum of weight. This gear with the 4" light foam wheels weighs a total of only 20 grams as installed.

Below: HXT900 9 gram servos for the elevator and rudder are mounted as shown below. I use 2mm CF rods with 1/32" music wire ends for control rods, with mini EZ connectors at the control surface horns. I make my control horns from 1/32" birch aircraft plywood.

Below : this is the battery mounting position for this build, easily accessible through the access door.

Above: The 4 servo KFm3 variant shaped airfoil wing mounted on the Highlander XL fuselage; flying weight at 16 ounces


A new 44" Span wing for the HIGHLANDER XL

Many years ago, while optimizing the wing design for the 84" span NITEOWL with it's flaps, I discovered that if the flaps were positioned farther out on the wings, out of the high speed rotating airflow from the tractor prop, that the deployment of those flaps would not cause the aircraft pitch changes ant where near to the degree that would be experienced if the flaps were positioned starting in close to the sides of the fuselage, within the prop's airflow. Leaving the trailing edge of the wing's center section un-flapped for the width of the prop was found to work so well, that the NITEOWL could make landings with its flaps in the full 90 degree down 'drag brake' deflection mode without destabilizing that giant scale aircraft... great for really slow landings.

That's why there is a stationary 9" wide section of this wing's trailing edge built into this aircraft- to see if the same minimal pitch disturbance upon flap deployment could also be incorporated into this HIGHLANDER XL.

(Note that the NITEOWL had a longer proportional tail moment and very generously proportioned tail group members; an even longer XXL version fuselage has been drawn up which will stretch the tail moment even farther back, but for now, I'll next test fly this new wing on this fuselage.

The airfoil is more carefully shaped on this particular wing build with carefully sized spacer spars to get close to the MH32's contours; a similarly built wing on the DANCER 5 has performed superbly in both clean wind penetration and low-drag glide performance.

SPAN : 44"  CHORD 8.8"  MATERIAL : 6mm FFF EPS foam, DOW Bluecor P/P  and 3mm black Depron EPS
Upper surface extends back to 50% of chord
Lower surface panel cut, control surfaces cut and tape bottom-hinged, then shaping spars added
 Upper panel cut, rolled to desired curvature, front edge angle-cut

Below; both spacer spars in place; Main spar at 30% of chord is formed from a 1/4" spruce full length spar with a 1/16" balsa filler spacer added on top; rear balsa spar spacer is 1/8 balsa with a 1/16" balsa filler cap strip
4 HXT900 9g servos laid out; Aileron servos are Y connected together to a single radio Rx connector.
Two flap servos also are  Y connected to a single radio Rx connector.
(I cut and splice wires, adding wire length where needed, soldering connections, then I use heat shrink tubing on all solder joints.)

Below: Wing's top surface panel is tape-hinged in place ( hanging down out of the way) ready for gluing; I use 6 minute epoxy for this gluing step.

Below, with epoxy applied, top wing surface is in place & held down with lead weights while the epoxy sets.

Below, the 2" wide  " 3p" aft top surface 3mm depron panel is glued in place & weighted to hold it while the glue dries; I use BEACON Fabri-Tac glue for this job.

Below- a look at the end of the wing panel structure before the wing tip plates are hot melt glued in place.

Servo linkages and control horns were added next.

Ready to fly at 17-7/8 ounces


MINIMIZING how flaps affect the Buschtrottel's pitch & stability

UPDATE 11-30-2021 : The high wind pattern of the last couple weeks finally let up this morning, so I had a chance to get out to do some test flying of The HIGHLANDER XL with the new 44" wing. This new design is handling very smoothly with great stability from full throttle to no-power glide, without and with full flaps.

With the balance set at 40% of chord and 4 degrees down-thrust on the motor, I now use only 1% Throttle>Elevator mixing to have a very modest climb under full power, and a smooth efficient hands-off glide attitude. This shaped airfoil KFm3p variant build handles full throttle power well.

Above: Closeup showing how much of the high speed propeller airflow going towards the elevator is affected by flap deflection; 8" prop for reference

Below: Closeup of the HIGHLANDER XL's wing center section trailing edge showing that the flaps start outboard from the prop's high speed airflow, so the Horizontal Stabilizer and elevator are affected far less when flaps are deployed;

requires minimal mixing of FLAP > ELEVATOR for very stable flight with full flaps

FLAP>ELEVATOR interaction was a major issue with the original Buschtrottel variant build ( It's flap chord was at 32% of the total wing chord); on my RD8000 transmitter, I had to program in -91% TH>EL mixing to eliminate the severe ballooning / nose-up pitching moment created when flaps were deployed.

With the HIGHLANDER XL's wing's stationary trailing edge panel, (and the flap chord at 23% of total wing chord) that ballooning / pitching up on flap deployment is greatly minimized; I'm only using a FLAP > ELEVATOR mixing setting of -5% on this design.

The result is an aircraft that handles smoothly & predictably, from full throttle, full flaps, to no throttle full flap landing approaches. The no power, no flap glide approach to landing is also smooth and predictable; it's just gliding in at a little faster pace. (The 3mm steps on this KFm3p variant shaped airfoil contribute to minimizing drag, for a more efficient glide.)

With 33% ailerons and 67% flaps, this aircraft still has great roll response for fun-flying; inside & outside loops, rolls, & flat spins are all done nicely. But it's optimized for slow flight and slow landings, and with a wing loading of only 6.7 ounces per square foot, it's light enough to really slow down nicely- even in this 71% density air up here in South Park.



Below: I decided to do an experiment on my first Highlander's wing, as shown in the photo below. I cut away the original flaps, then trimmed them down to 6-1/2" long by 2" wide these were cut from the original flaps, leaving the control horns and their EZ connectors in place. I then made a new pair of fixed replacement panels , hinged the flaps to them, and glued those panels into the wing. I used iron on laminating film over the glue joints to further reinforce the glue joint areas.

Flap servos were left in their original positions; new .032" music wire linkages were made to inter-connect the servos and control horns. I will report on the test flight results soon.



After a lot of takeoffs and landings, it became apparent that the light landing gear I'd made for my HIGHLANDER XL from 1/16" music wire wasn't getting the job done.... lightness is nice in an airframe, but on a bush plane, the landing gear has to be able to handle lots of takeoffs & landings on rough terrain.

So after returning from flying this morning, I removed the light landing gear and built up and installed some heavier-duty gear. This is a double-leg gear, with the main gear leg & axles made from 3/32" music wire. The rear brace legs are formed from 1/16" music wire.

The main leg was bent, then mounted loosely in place with nylon landing gear mounting fittings. The rear brace piece was then bent to match and mounted with four flange-head servo screws, The joining areas were then wrapped with kevlar fly tying thread, which was then coated with thin CyA glue. Last, I applied BEACON Fabri-Tac glue to all of the contact points so that nothing would be able to move out of place.

The result is shown in these photos.

The HIGHLANDER XL gained 1/2 ounce with this upgrade of the landing gear. With 2.69 square feet of wing area at 20-7/8 ounces flying weight, the wing loading is at 7.76 ounces per square foot. It glides very smoothly with power off with a fairly decent shallow glide angle, handles full throttle effortlessly, and performs aerobatics nicely, with a fine flat spin capability. It handles full flaps at full throttle smoothly (once the mixing of FLAPS>ELEVATOR is optimized.) It can also glide in at full flaps, no power, to a slow controlled landing; just don't flare into a stall too soon- timing is everything when doing no power full flap landings. [Having all of the trims and mixing fine-tuned makes flying this aircraft a real joy! ]



Below is the revised plan for the Highlander XXL fuselage with the floats; Rev. 12-20-2021

Below: the Highlander XXL on the right with the 44" span Kfm3p wing on the right; To the left is the Highlander XL with the deeply under-cambered slow flyer wing


Below: bending guide for the float mount gear

Below: rear float mounting gear leg mounted to it's fuselage plate; all axles are 1-1/2" long,

so they will pass through the floats' mount blocks with 3/8" extended out where wheel collars will be installed.

(I may add a .042" diameter music wire 'spreader' to the rear gear leg; I may also add top front to bottom rear .042" diagonal brace wires to keep the gear from deforming during landings;
they may not be needed on this lightweight aircraft.)

Below: four float side panels cut and marked for where the formers are glued in place

Below: formers glued in place on one float side panel. I use 1/8" thick firm balsa for the formers which tie the gear loads at the gear mount blocks into the float structure.

Some extra balsa triangle stock blocking will also be added under the mount blocks. Two other foam formers will also be added, not shown in this photo.

Below: float's second side panel glued and pinned in place

Bottom hull forward from step is made from 1/32" thick 3 ply birch plywood; the aft hull bottom behind the stem is made from 3 ply 1/64" thick birch plywood.

These panels are lightweight, yet very strong, and hold very clean edges for great handling on the water (or snow).

Note that 2 extra foam formers and balsa blocking under the mount plate area have been added to the interiors of the float.

Below; lead weights hold the hull bottom panels tightly in place while the glue dries.

I'm using BEACON Fabri-Tac glue for most of the float assembly- it dries totally waterproof, but does require some drying time.

The forward hull bottoms have the ply grain running cross-wise on the hulls; since the sheet it is cut from is only 12" wide,

a second piece needed to be added close to the nose. An extra balsa former supports this joint on the inside of the float.

Below: completed floats mounted on the HIGHLANDER XXL Fuselage

101 grams for the set (before covering with a waterproofing layer of iron-on laminating film.)

For reference, the two 4" tundra tires weigh 64 grams for the set

Below: a 9" x .040 music wire 'spreader wire' was added to the rear float mounting gear leg; added weight of only 1.4 grams

Below: Floats waterproofed with 1.5 mil and 3 mil iron-on laminating film, which brought up the weight of each float to only 2 ounces.

BELOW is the Highlander XXL on it's floats sitting on 5.1" of fresh 'champagne powder' snow

CLICK TO Go to Bruce Stenulson's main RC Flight page

Web sight designed and maintained by Bruce Stenulson, Fairplay, Colorado. (c) 2021; All Rights Reserved.