SkiGull Description & Walter Mitty Plan

| Burt Rutan

My 2011 retirement started with a year not doing any design/build, and questioning if I had the persistence to develop another aircraft.

I then spent 2 years doing preliminary designs of a very special airplane, the SkiGull. The design was recently changed to use a modified version of a certified Rotax engine (turbo, E- fuel injection, flight-adjustable prop, 130 max BHP) and the structural materials changed to be completely compatible with seawater. This is tough, requiring the use of only composites or titanium. It has zero aluminum and many systems, like flight controls and skis are all-composite using iGus plastic bearings. Any saltwater corrosion proofing that cannot be done is limited to LRUs that can be easily replaced while operating remote.

The local DER who is helping me build it is 6-ft 8” tall. He fits nicely in either seat and can even stretch his legs and toes fully forward without restriction. Both forward and aft cockpits are similar to the Long-EZ’s forward cockpit, except they are 6” longer and 10” wider. The huge baggage area handles over-size things like golf clubs, snow skis, fishing poles, etc. A unique new system allows loading the lengthly cockpits and the baggage area extending to the tail without exceeding cg limits.

The most-obvious feature of SkiGull is its retractable ski system. Pneumatically deployed at 15 knots during water takeoff and supporting the weight down to 10 knots during water landing, they provide six-times the shock absorption deflection of a landplane, while all other seaplanes (except the 1950s Sea Dart) have Zero-shock stroke. This allows it to operate in most beach waves, large ocean crests and very rough lake/river water. It can operate from water with the skis retracted, but it then is severely limited to relatively smooth water, like all other seaplanes. The skis have small wheels that protrude only 0.8” out the bottom, allowing it to operate out of snow, grass, hard surfaces – all surfaces can be rough-enough to destroy a conventional aircraft that does not have the large stroke of the SkiGull’s Cf flexible skis. The Tri-Marine hull and retractable skis were tested at full scale on Lake Coeur d’Alene in 2013.

All performance info below is ‘estimated.’ While drag and stability/control has been measured with full-scale hydrodynamic tests, to validate water takeoff performance and safety, the aircraft has not yet flown.

Its docking system is two, 5” diameter electric motors each driving a 27” diameter folding prop. These self-contained units (Off-the-shelf motor, controller, batteries used for giant RC models) mount on each wing. They provide forward or reverse thrust to allow backing up or rotating when docking/beaching in winds. Since the SkiGull has an L/D of 23 (it looks more like a motor glider than other seaplanes/floatplanes), its electric docking system can fly it about 8 miles, which greatly reduces the risk of an engine failure, particularly when operating out of small tree-lined lakes. Every other seaplane has to crash straight forward when an engine fails early in the climb, a SkiGull can fly back to downwind & land on the lake into the wind. The docking system also gives it an extra 150 lb thrust, for that over-gross water takeoff when heading for Hawaii.

SkiGull can loiter up to 35 hours at about 15% power at 1700 RPM making it inaudible when above 400 ft AGL. This allows you to sneak in during daylight with low detection risk.

It now should have the range to make it from Calif to Hawaii without ferry tanks. It retains its STOL capability, and ability to use water/snow/ice/grass/dirt. It can use an airport, but since it uses car/boat gas and stores in a single garage, I will probably rarely go to an airport. To avoid flying in darkness on the Hawaii trip, we will fly during a low sea-state, land and sleep on the ocean in two hammocks stretched from the two wing-fold fittings to the tail.

I know it sounds like Walter Mitty, but if it flies well Tonya and I will explore the world with it, visiting the places you cannot easily get to any other way. Imagine being able to land in large swells near any ocean shoreline, ride the waves to the beach, then hike for lunch and gas. Since it gets 60 mpg you can carry 400 miles of gas in the type of backpack/bladders that cross-country dirt-bike racers use. Imagine also going to snow fields anywhere there is about 400 ft of relatively smooth snow, or to a dirt patch right at Puma Punku, or any part of the Amazon, including the tiny rivers that feed it. Imagine doing a 8 month exploration trip around the world without EVER going to an airport.

I am also working on a method to do the exploration with all of it being in good weather – I need to avoid any severe conditions, especially strong surface winds that can destroy an airplane tied up on a beach or river and unable to find a hangar for shelter. To do this requires a retired crew that is not stuck to a schedule or a planned route. Think about it; a planned route just takes you to the places you know about, and likely to places that other “tourists” go. That is NOT exploration. Instead, you need to be driven by some unknown random function to give you those cool opportunities to discover unknown fantastic places scattered about the boring landscape (or seascape). I have been gathering data every day from this website to validate the crazy idea that by merely staying in large high-pressure systems (or using the 2,400 nm range at 23k ft or half that range at 170 knots to side step to an adjacent high-pressure system), you can do the whole multi-month exploration, all in good weather.

Like the Icon A5, the SkiGull fits in a single-car garage, even though it has a 44-ft wingspan (wings fold and 5-ft wingtip panels are removed). It requires just three, 25-inch components to allow it to self-trailer without needing a conventional boat trailer.

At RAF, I developed 6 airplanes marketed for homebuilders to enjoy. I always immediately started on the Next acft, thus never really got to enjoy those airplanes myself (except for Defiant, where I have most of my flying hours). The SkiGull will be different; it will be the last time I design and build an airplane since I want to enjoy this one for myself.

Burt Rutan

4 Responses to “SkiGull Description & Walter Mitty Plan”

  1. Jaime G Sada

    Have you performed a test or made calculations of how much power is needed to get the skis to the speed for them to be able to plane on the water ? (15 kts)
    Will you be using more than one turbocharger to be able to fly at FL230 ?
    What about the need for oxygen at that altitude ?

    Reply
  2. Tony Accurso

    Hi Burt,

    My daughter and I are so excited to see you designing one final aircraft. Though we miss you here in the High Desert, retirement in Idaho looks fantastic. Thankfully, living north of the Rosamond Airport, we are always watching your designs flyover and just smile thinking of you.

    Best of luck with the SkiGull, we’ll be closely following your progress as information is posted.

    All the best,
    Tony & Evelyn Accurso
    Rosamond, CA

    Reply
  3. mp3juice

    Your style is unique compared to other people I have read stuff from.
    Thanks for posting when you have the opportunity, Guess I’ll just book mark this page.

    Reply

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