Since Flying K Enterprises’ Sky Raider arrived on the scene 4 years ago, the ultralight design has achieved excellent success in the market selling more than 140 kits (not including the 65 or so fuselages shipped to SkyStar Aircraft which they use for their Kitfox Lite). However, the company behind the Sky Raider design has suffered in nontechnical ways.
Original Flying K principals brothers Ken and Stace Schraeder split up and started separate companies making ultralights. Then, only months after the split, Ken Schraeder was killed while flying a Sky Raider (see “Flightlines – Kenny Schraeder Killed in Crash,” April ’00 Ultralight Flying! magazine).
Despite these setbacks, the Sky Raider flies onward. In fact, Flying K Enterprises seems to be healthy and energetic despite the twin losses.
When the company shows their Sky Raider floatplane model and an example of their coming 2-seater, crowds often flock around the ultralights. I was full of anticipation to see how the floatplane would fly.
Making a Splash
During the April heat of central Florida, a floatplane evaluation sounded like a doctor’s prescription. Lake fly-ins, or “splash-ins” as they’re often called, don’t seem to attract the same huge crowd as land-based fly-ins. In truth, seaplanes of all shapes and sizes represent another of aviation’s many niches. The fascinating aspect of seaplane gatherings, though, is how they span the spectrum of aviation. At Florida’s Lake Parker, aircraft weren’t pigeonholed into ultralights and trikes, general aviation floatplanes, dedicated amphibians, or twin-engine seaplane-based transport planes. All those types were present but they gather as, well, seaplanes. And from my view on several occasions, seaplane pilots have a ball.
Much of a splash-in is the same as a fly-in. Lots of time is spent on the ground ogling or examining everyone else’s floatplane. New, old, even antique… big, small, heavy, light… high wing, low wing, floats, boathull seaplanes and more I probably missed.
In the air on approach with several other seaplane types, or along the shoreline with lots of other floatplanes, the Flying K Sky Raider on its silvery aluminum floats drew admiring stares. A snappy paint job helped, but I think it was mostly that the little single-place Raider looks like fun even when pulled up on the shore.
Grant Rappe was my check pilot, instructor, and ultralight facilitator. Helping Flying K at the splash-in was easy for Rappe as he has his own float Raider. Combined with his friendly, helpful attitude, Rappe was an asset for Flying K.
In one display, I saw him win the grudging admiration of many general aviation floatplane pilots as he approached a crowded pier and shoreline to bring the plane to a dock for me and my camera.
In the busy docking area general aviation planes shut down 100 feet out – you can’t bring a seaplane to a complete halt without shutting down the engine and you can’t have it creeping along with other planes close by. A small boat ran out to tow planes in for a beaching.
Rappe simply hopped out of his float Raider, whipped a plastic paddle from behind his seat, and began paddling himself right to the dock. He made it look easy and light winds were cooperative. (The plastic paddle breaks down into two pieces, handy for use in any seaplane.)
I had no real way to measure the length of my takeoff runs. Being intimate with the float Raider, Rappe says he is able to break water in only 4 seconds. Flying K expects to move the floats back a few inches and think they can cut the water time to 2 seconds. Even without figures, I can confirm it lifted from the water exceedingly swiftly. The Sky Raider made repeated water takeoffs and landings a thrilling and enjoyable experience.
With the float package in unpainted aluminum and with less paint and few options, Sky Raider representatives say you can build a Part 103 ultralight floatplane from their kit.
Though lots of Ultralight Flying! readers have pilots licenses, too, it’s still best for many ultralight buyers if the object of their desire can be flown under the rule of Part 103. Let’s look at this from the ultralight floatplane perspective.
For those checking out regulations governing floats (or ballistic parachutes), Part 103 needs clarification. At least that’s what FAA thought after releasing their simple ultralight rule back in 1982. One of the documents they created to help understand Part 103 was AC-103-7
Advisory Circulars (ACs) are partly intended for FAA field officials, in this case to use in determining whether a certain ultralight vehicle meets the definition. The vagueness in Part 103 is some of its beauty; what isn’t prohibited may therefore possibly be allowed, better than having endless rules that tell what you can and can’t do. However, vague references need to be interpreted at times and the ACs give FAA personnel guidance in making such interpretations.
The relevant section of Part 103 – Subpart A 103.1(e)(1) – says an ultralight vehicle must weigh no more than 254 pounds empty “excluding floats and safety devices…” What kind of floats? How many floats? How much can they weigh? You must turn to AC 103-7 for clarification.
If you have “floats used for landings on water” then you may increase the empty weight by “only the weight of floats and any integral external attachment points” (I put the emphasis on external). All other hardware used to assure the airframe can handle the floats is included in the vehicle’s empty weight. Fortunately, extra reinforcements are minimal as ultralights leave the water so quickly that they transmit little strain to the fuselage. Contrarily, a float-equipped Cessna uses extra steel supports at strategic points inside the fuselage.
Given the language of 103-7, can floats have any weight the designer wants? No more language in this circular regards straight floats, that is, ones with no wheels for use on land. Amphibious floats do come with further language and oftentimes this language is used to set the weight of straight floats.
In AC-103-7, item 18.a.(2)(b) states that an amphibious fuselage (boathull design) can add 30 pounds to the basic empty weight and that another 10 pounds may be added for each “outrigger float and pylon.” With this definition, the boathull, dual-outrigger Aventura can weigh up to 304 pounds (254 + 30 + 10 + 10), or up to 328 pounds if it also has a parachute (up to another 24 pounds allowed).
As a further condition, the extra weight is allowed only if the ultralight will be used for “repeated water takeoffs and landings.” Operators may be required to demonstrate the water capability in order to receive the allowance for added weight.
FAA’s way out of any doubt is to say that float provisions not discussed in 103-7 should be reviewed with FAA personnel.
Referring to boathull amphibians, AC-103-7 also states that 30 pounds is “the average weight of a single float,” it is often interpreted that this means you can have up to 60 pounds additional for straight floats, such as used on our test Sky Raider. However, this figure is not specifically stated, and based on the words that are presented I would argue that the floats can weigh whatever they do right up to the point where they connect to the basic airframe. Of course, light is always good on all aircraft, but the language of 103-7 does not prohibit heavier, more sturdily-built floats.
Assuming an allowance of 60 pounds for the floats (30 each), the float Raider total can be 314 pounds empty or 338 with a ballistic parachute system. If you’d like an amphib gear system for the Sky Raider should one become available, FAA will allow no more weight for the extra mechanisms involved.
Sky Raider floats are built in the Czech Republic and are based on a Chris Heinz design. They weigh 28 pounds each. Rappe referred to them as Zenair floats, and reports the Czech company bought the rights from Heinz.
Part 103, But How Does It Fly?
Although the 26-hp Rotax 277-powered Sky Raider I flew 3 years ago did respectably well, the twin cylinder 40-hp Rotax 447 makes for smoother operations, especially at lower power settings. You can do all you want in the air while running the engine at 50 or 60% power. Less vibration is present and therefore the airframe is less subjected to this ongoing form of damage.
The Rotax 447 float Raider is so sprightly that the only reason I can see for the 50-hp Rotax 503 is if you love that engine (or already own one perhaps). Maybe if you live in a high elevation or if you are particularly large, the bigger Rotax is needed but the 447 was certainly sufficient for me (average FAA weight) on a hot, humid day in Florida (roughly sea level). Nonetheless, many buyers pick the Rotax 503, so well-regarded is this engine. Should you make this decision, Flying K will insist you buy the larger elevator option for $150.
Sky Raider’s entire fuselage comes prewelded and I’d select the quick-build wings for $400. “The ribs and false ribs are already glued to the spars,” reports builder Bert Croy. You can also select the Wings Set to Fuselage option for another $400.
The 277-powered Sky Raider I flew weighed only 237 pounds. You’d have to add a lot of stuff to exceed the 254-pound weight limit when built that lightly. This suggests keeping a float Raider with a Rotax 447 inside the 314-pound limit isn’t unreasonable.
After Rappe got me secured inside the cockpit, I was ready to head out onto the open water of Lake Parker. It’s a big lake that I’ve flown several times. The day was mild and inviting and I couldn’t wait.
Duty called first, though, and I was required to make several passes before Ultralight Flying!’s editor in chief Scott Wilcox’s camera. We’d arranged to do this where the lighting was good, but that meant I had to maneuver in a narrower portion of the lake before I could see how she would fly. This proved a good lesson as you’ll see.
On the Sky Raider a pull starter was located under the control panel, hanging off the firewall. This isn’t a handy spot should the engine die out on the water but it was accessible and I was able to do starts on the water while strapped into the seat.
A more convenient handle operates the flaps. Closely placed just to your left as you sit looking forward, clear detents are also easy to find (though I must admit I found the lever a tad awkward to position). Flying K has addressed this with an optional push-button flap hand for $175. After a few landings, I got the detents down pat and don’t believe I’d order the option.
The floats ($2,800) are new to Flying K and it showed in the lack of water rudder. Taxiing on floats is an interesting experience. If you face directly into the wind or up to about 45° cross, the aerodynamic rudder works well. Downwind you use a little prop blast to keep it going. I used 4,000 rpm for downwind taxi. Slightly more than that seemed to offer good authority.
Once I’d worked my way back into the narrow passageway off Lake Parker to position the Sky Raider for the Nikon’s lens, I needed to turn from downwind to upwind. I mistakenly added power and only propelled myself quicker toward the shore. Then, I remembered. In this situation, back off the power and let the aircraft weathervane into the wind. You only need power to swing her away from the wind. Going upwind again, Mother Nature takes over. Sure enough, as soon as I reduced to idle thrust, the float Raider swung cooperatively into the wind and posed nicely for the camera. About this time I saw Rappe signaling me that I’d figured it out (to his relief, I’m sure).
Water rudders can change this whole equation and make the ultralight more maneuverable in tighter conditions or when the wind is blowing uncooperatively.
Float Raider’s aerodynamic rudder is still the same as the original but Flying K is adding one that is 11 inches taller to bring more control for float operations, probably offsetting the common floatplane need for a ventral fin. I doubt this will eliminate the need for the water rudders, though.
After a few repetitions that went smoothly, Wilcox waved me off, indicating he had the photos he needed. Now, we fly.
Good to Go
The first takeoff was gentle, with one notch of flaps to help break water, and a steady, slow increase in power. I’d checked traffic through the overhead skylight and I was in the clear for several minutes at least. Because I went slowly, the Raider and I didn’t get off as quickly as subsequent trials but the effort was simple.
Getting up on step was easily identified and the float Raider zipped up to liftoff speed quickly.
Rappe recommended one notch of flaps for takeoff. I experimented later with none and he’s right to advise some extra curvature. It got off the water noticeably faster.
Two flap positions are possible; one is 10°, the second is 35°. They work quite effectively on this genuine ultralight, and I observed that Sky Raider can fly approaches at 40 mph using flaps.
The flaps were good aerodynamic surfaces, steepening the approach path correctly but also helping slightly, I believe, to help break the surface quicker. My only gripe about the flaps is that even when I slowed to 45 mph, the flap handle took considerable muscular effort to fully deploy.
Flying K offers a wing tip kit that extends the wings 21.5 inches to a span of 28 feet. The area increases 10% to 107 square feet from 98 square feet. I believe I’d order this for $200 as it should produce lower takeoff and landing speeds – and shorter water runs as well, I expect – plus it will tend to fly a bit more slowly. It might detract from the snappy handling somewhat but Sky Raider is so good in this respect that a few percent loss would hardly be missed.
Visibility on approach is quite good in the little Sky Raider and with the overhead skylight, your upward vision is also excellent. Skylights seem one of the “bright” ideas in ultralights, especially when flown in other traffic like the crowded conditions at the Lake Parker Splash-In. However, good as it is up and down, lateral vision help from the skylight doesn’t start until you’re banked over 30°.
With your raised position inside the cockpit, you can clearly see the wing folding pins are in position. Some folks want to cover up the parts of an airplane interior, but here’s an argument for openness when it provides reassuring feedback.
Speaking of open, Sky Raider’s instrument panel was what you might call “Randy Schlitter-type panel” in that there’s no top to it. Pilots who don’t like to see the guts can surely create a lightweight cover for the instrument panel.
Almost as soon as you leave the water, float Raider’s cooperative handling makes itself obvious.
High points are deserved for the Sky Raider’s handling. Again, I recalled my flights in the earlier Sky Raider, two Kitfox models, and SkyStar Vixen. All offered very snappy aileron response, and generally light forces overall. So does the float Raider.
My tape-recorded notes reminded me that coordination was certainly adequate but the aileron forces were lighter than the rudder, again just like the Kitfox.
Excitement in the Air
At full power at approximately ground effect height, the ASI showed 65-70 mph, suggesting the design may not be held back by the float drag. However, I must add my usual refrain about the ASI accuracy not necessarily being good.
I had a similar problem with climb measurements on the float Raider. Flying K used a small 2-inch face altimeter. On such a small gauge and without three needles to help precise reading, I could not rate climb speed very well. Less than half an inch of needle movement covers 1,000 feet. Despite this equipment problem, climb seemed to be in the range of 500-600 fpm with the Rotax 447. Flying K reports it should be more than 1,000 fpm in the wheeled version, so either the floats cut climb performance notably, or the day’s density altitude was very high, or my technique was poor.
Rappe’s personal Sky Raider has a 35-hp Rotax 377 and he says it does fine, plus he reports a float Raider is flying well with a Rotax 277.
In all the stalls I practiced, I found none with unusual reactions. Most were downright dull, a great characteristic for any ultralight.
I imagined the snappy roll response would translate to a high level of adverse yaw, but in fact it’s only in the medium range. Beginning pilots should have no trouble making coordinated turns. Experienced pilots will love the float Raider’s handling qualities, I think.
Sky Raider’s standard kit price has only kept pace with inflation since it was introduced in late 1996. Today’s complete airframe kit costs $8,500, which includes: cowling, motor mount, airspeed indicator, wheels and brakes, fabric with adhesive and reinforcement tapes. This is a pretty complete package at a competitive price and you get your choice of color for the powder-coated steel. You could shop for a used Rotax 447 and get in the air for under $10,000. But if you opt for new or if you go for the Rotax 503, you’ll spend $12,000 or more.
Add the Czech floats and a couple simple options and you’ll reach $15,000. For a float plane, that’s a good value. If you build lightly and keep it under 314 pounds, you’ll also have a Part 103-compliant float Raider.
Flying K has a long list of optional extras you can use to get rid of all the pesky extra money you have. Or you can stick with the plain version that has all the important parts any ultralight seaplane should have.
Either way, I recommend you speak to the Flying K factory or a closer representative and go check out a float-equipped Sky Raider. Great as it was as a ground-based single-seater, on floats, it’s simply a dreamboat.
|Empty weight||309 pounds (including floats)|
|Gross weight||550 pounds|
|Wing area||98 square feet 1|
|Wing loading||5.6 pounds per square foot|
|Kit type||Construction with quick-build options|
|Build time||250-350 hours|
|Notes:||1With wing tip, area increases to 107 square feet. Created to facilitate sale into Canada.|
|Standard engine||Rotax 447|
|Power||40 hp at 6,500 rpm|
|Power loading||13.8 pounds per hp|
|Cruise speed||(75% power) 65 mph|
|Never exceed speed||100 mph|
|Rate of climb at gross||1,000 feet per minute2|
|Takeoff distance at gross||200 feet 3|
|Landing distance at gross||50 feet 3|
|Notes:||2Performance without floats; not accurately measured with floats.
3Estimated performance on water (no measurements taken); factory states land performance is 75 feet, takeoff or landing.
|Standard Features||Fully enclosed cockpit, folding wing setup, slotted flaps and ailerons, brakes, steerable tailwheel, fiberglass cowling, engine mount hardware, choice of tail shapes, all fabric and adhesives.|
|Options||Rotax 503 engines, electric trim, prop, bungie cord suspension, floats, skis, ballistic parachute, tundra tires, baggage holder, quick-build kit, and many more items.|
|Construction||Welded steel fuselage, wood and aluminum wings, fiberglass cowling, dope-and-fabric wing coverings. U.S.-owned company.|
Cosmetic appearance, structural integrity, achievement of design goals, effectiveness of aerodynamics, ergonomics.
Pros – Single-seat ultralight has proven very popular since first debuted 4 years ago. Though company has gone through some difficult times the design survives very well. Float-equipped Sky Raider can qualify as an ultralight under Part 103 if builder is careful (given the extra weight described in AC-103-7). Steel structure with wood-in-wing construction plus fast-build options make for a reasonable effort.
Cons – Though sales have been good, single-seater may attract fewer buyers on resale. Choice of Rotax 447 or Rotax 503 is better for float operations but will add to challenge of remaining within Part 103 definitions. If used continuously in water operations, wood used in wings may require closer inspections (than metal) as design ages.
Subsystems available to pilot such as: Flaps; Fuel sources; Electric start; In-air restart; Brakes; Engine controls; Navigations; Radio; (items covered may be optional).
Pros – Flaps worked well and aided landing approach well; simple, easily-found control lever. Pull starter worked acceptably well from the cockpit. Floats were simple straight models with no gear retract weight or complexity. Like all simple planes, you have less to go wrong – a good fact for ultralight newcomers to remember.
Cons – No aerodynamic trim. Flaps resist deployment at higher speeds. Cowl must be removed to work on engine; inspection is more difficult. Pull starter handle hangs off firewall where it could prove to be a challenge to find during an in-flight emergency. Fueling on the water insists you put the correct wing over a dock.
Instrumentation; Ergonomics of controls; Creature comforts; (items covered may be optional).
Pros – Entry is simple, leading with your rear then swinging legs; most pilots will think it’s easy. Panel large enough for all the instruments you want and still have room for a radio. Four-way seat belt system installed. Cargo container is optional if weight and balance will permit. Seat was well padded; good on longer flights.
Cons – Seat does not adjust for different sized pilots. Low seat back provides less support. Fuel routes through cabin from wing.
Taxi visibility; Steering; Turn radius; Shock absorption; Stance/Stability; Braking.
Pros – 0verhead skylight is excellent to observe conflicting incoming traffic; extremely useful in water ops where pilots can land anyplace. Authoritative ailerons allowed good control while taxiing up- and downwind. Floats drafted little and seemed positioned well (though they’ll be moved aft a couple inches).
Cons – Water rudders were not yet fitted, making water taxiing much more uncertain (though it went fine with good technique); turn radius can be quite large. In-wing fuel source will mandate one wing is hanging over dock; otherwise you’ll stand on a slippery float to accomplish this.
Qualities; Efficiency; Ease; Comparative values.
Pros – Sky Raider launches have the features any ultralight seaplane should: very short water run, powerful control, good initial climb. Landings also went well: good visibility, slow approaches – you can arrive below 40 mph even with float drag. Flaps are helpful to speed liftoff and to slow approach speeds.
Cons – Landings with no water rudders mean you should plan your approach better so as to allow adequate space for maneuvering. Slow water operations may prove challenging for newcomers until water rudders are added (they’re coming, says factory). Floats offer little standing area for paddle operations. One notch flaps needed for best operations.
Quality and quantity for: Coordination; Authority; Pressures; Response; and Coupling.
Pros – Rapid roll control and response; I loved it though some new pilots may find roll rate too fast. Dutch rolls and precision turns were delightful. Controls were very light in touch and very predictable. Floats seemed not to affect control responsiveness. Flaps were quite useful on approaches and to help break water surface earlier.
Cons – Harmony isn’t perfect; roll was faster-acting than the rudder. Responsiveness of controls will require a less experienced pilot to pay closer attention (though this is an easier adaptation than stiff controls). Flap handle proved to offer considerable resistance at speeds above 45-50 mph. Generally hard to fault this well-evolved control system.
Climb; Glide; Sink; Cruise/stall/max speeds; Endurance; Range; Maneuverability.
Pros – With 40-hp Rotax 447 or 50-hp Rotax 503, Sky Raider is an enthusiastic performer (503 can climb up to 1,600 fpm without floats). Left water quickly, which helps preserve a seaplane. Sink rate appeared quite low despite added weight from floats. Overall package makes single-place float flying simple, yet fun and energetic. If floats held back Sky Raider’s speed, I couldn’t tell it. Low-over-the-water flying is absolutely joyful.
Cons – Engine must work a little harder to carry the 28-pound floats (each). Land version fuel consumption is listed by factory at 2.5 gph but seemed to go faster in seaplane operations that included extra power for water maneuvering. Range on 5 gallons will be limited.
Stall recovery and characteristics; Dampening; Spiral stability; Adverse yaw qualities.
Pros – Nose broke in stalls but not steeply. Longitudinal stability seemed good with few oscillations before level recovery. Adverse yaw less than expected. Power response was correct, that is, nose up on power up. Good stick range throughout maneuvers even with extra float weight.
Cons – Stalls were a bit less modest than I recall on land version with 26-hp Rotax 277 engine, perhaps due to extra weight and possibly added drag below center of gravity. Speed builds up rather swiftly on sharp nose-over.
Addresses the questions: “Will a buyer get what he/she expects to buy, and did the designer/builder achieve the chosen goal?”
Pros – The Sky Raider has proven itself successful in the marketplace with agile handling, good performance, popular looks and low price ($8,500 for base kit; about $15,000 as tested with floats). With 40-hp 447 engine, you must build carefully to stay within Part 103 but you get robust performance. Comfortable cabin with full enclosure option. Vast list of options helps you make Sky Raider your very own.
Cons – Potent Rotax 503 engine, fancy paint, and many accessories will force you to N-number your aircraft; will also bid price up significantly. Floats don’t have a lot of history to suggest how they’ll last over time.