Seawind Piloting
The ISPA extends our thanks to Dick Silva and others who have reviewed and provided input for this page.
The intent of this page is to provide information about flying the Seawind. The point is, the Seawind can be flown by any pilot with the proper knowledge and training, even low time pilots, but as with all airplanes, training (by the proper instructor with Seawind specific experience) and practice are essential. The single most critical factor in Seawind Safety is the pilot.
An airplane might disappoint any pilot,
but it'll never surprise a good one.
(Len Morgan)
Introduction & Fundamental Characteristics:
(An Extremely Brief Summary)
Thanks to the efforts of many experienced Seawind pilots, and their willingness to help, there are several low-time pilots with somewhat limited experience now successfully and safely flying their own Seawinds. The advent of the new certified Seawind now promises to make this dream possible for many others.
This wasn't always so. The Seawind is a complex high performance airplane. The need for pilot experience specific to the Seawind just cannot be overstated. This fact was learned by pilots as early as those who flew the Creelman prototypes. As roughly summarized from elsewhere on this site, in early water operations testing of the first prototype, the test pilot struggled with attempted water take-offs. On the last occasion for prototype one, after skimming along the surface of the water for a mile or two without lifting out, the test pilot decided to abort the attempt and dumped the power. Mostly because of the high centerline thrust characteristics (the prop's resistance to the air acting as a brake located at a moment arm above the CG) the abrupt loss of power caused the airplane to pitch-up and launch. It jumped off the water and into the air an estimated 150 feet. It then stalled, slammed into the water, and sank. Luckily, the pilot survived, but the plane is still on the bottom of the lake.
As already learned from the postings on the ISPA discussion board, pilots should not attempt a deep, power off stall in a Seawind. Upcoming certification testing will characterize this more definitively, but it is generally accepted that power is required to recover from a stall/spin situation in a standard Seawind. Without power, the wind milling propeller and fuselage may partially block air flow to the elevator and rudder. There are bound to be dozens of facts like this that each of us needs to know. What are they? Knowing them could be a matter of life and death.
High Thrust Centerline:
Just one piloting characteristic of the Seawind is that it has a high thrust centerline. It is certainly not the only airplane to have this characteristic. A high thrust centerline is created when the centerline of thrust is above the centerline of the airframe center of gravity (CG). This displacement causes the forces being created by the power plant to act through a moment arm about the CG. Simply stated, this results in flight responses that may be opposite those in 'standard' aircraft. The pilot action of adding power results in a reaction that pushes the nose down, not pulling it up. Power reduction pulls the nose up. Of course, there are other effects of high centerline thrust on yaw and roll as well, but in general, they are not as prevalent as the effects on pitch.
Pitch Control of Aircraft With A High Thrust Centerline:
The magnitude of the forces pushing the nose up or down are a function of how rapidly the power changes occur. Pilot induced power changes are usually done in a slow and controlled manner. Also, since the pilot is making these changes, he or she will anticipate their affects. When an engine suddenly loses all power completely, the situation can be quite different. Two things work against the pilot in this situation. First, if the engine suddenly quits while under full power, the magnitude of the nose-up force can be huge (300 HP to 0 HP in a fraction of a second). Second, the pilot's reaction time enters into the picture. Rather than anticipating what is about to happen, before pilot action can begin, the pilot must first assess what has happened.
When the plane is in a climb, this is especially important as the pilot must take proper action to avoid stalling, and if at low altitude, crashing. Trying to simulate this condition can be dangerous, and because of pilot anticipation and other variables, not always accurate. This clearly falls into the category of the following: "The emergencies you train for almost never happen. It's the one you can't train for that kills you" (Ernest K. Gann, advice from the 'old pelican').
About stalling and stall training, ISPA member John Ricciotti, in his post Post #399 in our discussion board (The Hangar) makes several interesting and informative points. Some airplanes can eat up thousands of feet of altitude before the pilot and plane recover from the stall and resume sustained flight.
In general, the CG of an airplane is centered within a small area near the aerodynamic center of the wing. Forces on the airplane cause it to rotate about that CG. For this discussion, in order to visualize how this rotation occurs, imagine taking a model of the Seawind and putting a stiff wire rod right through the center of the wing from tip to tip. Imagine how the nose reacts when the engine is pushed fore and aft with a finger. Bear in mind here that we are only considering forces affecting pitch, there are also forces affecting yaw and roll that further complicate the equation.
In actual operation, the primary forces are those of the engine (prop) and those of the elevator. When the engine is developing thrust, and the prop is higher than the CG, the resulting forces are pulling the plane forward and pushing the nose downward. Lift at the wings is acting to hold the plane up (like the wire rod above). The downward force at the nose must be counteracted by a downward force at the tail in order to keep the plane in level flight (like a seesaw).
The force at the elevator is created by moving the elevator up or down into the air stream flowing over it. On most airplanes, the magnitude of air flow over the tail can be effected by what the prop is doing. This is especially true in the Seawind. Note how the elevator and rudder are in the "air-stream" of the prop.
When the engine quits without warning to the pilot, there is a finite time delay before he realizes it. During this "reaction time," the elevator will remain in the same position, or if back pressure is being applied, may even go up (adding even more tail-down/nose-up force).
In a sudden loss of power, the drop in engine force will occur quickly, ahead of the decrease in elevator force. With the imbalance of up and down forces, the nose will rapidly move up (dubbed pitch-up). A certain upward momentum will have to be overcome before the nose can be lowered. If the plane is climbing, it may even stall. At low altitudes, there may not be enough room to recover.
When the elevator is finally put in the downward position, the forces are roughly as follows: With a stopped or almost stopped prop, the prop creates drag, and the forces are reversed from what they are with the engine producing power. There is a force trying to slow the plane. The drag also induces an upward force, which acts to lift the nose. In order to get back to flying speed, it is necessary to get the nose down. The elevator must produce a force sufficient to counteract the drag of the prop. Not only is the airflow across the elevator reduced by the lack of airspeed, but it is also being blocked by the prop (rather than supplied, i.e., a doubling effect).
When power is reduced by the pilot, things happen at a much different rate. Because the pilot is anticipating the change (even subconsciously) reaction time is not as much of a factor, or even no factor at all. Since the power is being reduced at a slower rate, the imbalance of vertical forces is less. Since the prop is still being turned by the engine (as opposed to removing energy from the air flow) there is considerable wind generated for the elevator, and you do not produce drag due to a wind-milling prop. The elevator is operating in air that is energized by the prop, and there is not a huge nose up force from the prop. In this case it is much easier for the elevator to produce the required upward force to get the nose down and the plane flying again.
Seawind Roll Characteristics:
Roll is another factor that enters into the handling characteristics, particularly stall and potential spin. Like many other airplanes, fuel tanks make up the leading edge of the Seawind wing. The main tanks are inboard and auxiliary tanks are located in the outboard bays. Depending on several variables, the tank venting system, and fuel consumption in the Seawind can sometimes cause an imbalance in fuel from side to side. For this reason, the system includes provision for pumping fuel from side to side to keep the system balanced. This is necessary not only for operation on the water, but when in flight as well.
The fuel system has been designed with check valves, pumps and other design features to accommodate all of these imbalance possibilities. Of course anything is possible, but in certain flight conditions, and if by chance a check valve malfunctions, it is possible for fuel to be forced from the main tanks to the auxiliary tanks and a resulting imbalance. These factors require pilot vigilance and awareness concerning proper fuel balance.
Again, the location of the engine above the CG can become a factor in roll response. Note that as the airplane rolls one way or the other, the mass of the engine will have a sort of "upside-down pendulum" effect on overall CG.
As you can see, a fuel imbalance can become a factor in Seawind stall response. If one wing is heavier than the other, that side will have a tendency to drop during a stall. Seawind pilots have reported several variations of stall response in the Seawind. Most of the time it is reported that the nose drops straight during a stall, but there have also been occurrences when one wing or the other would also have a tendency to drop. As mentioned above, deep power off stalls are not recommended in the Seawind.
Water Operation:
There are as many opinions about flying the Seawind as there are pilots. One almost universal opinion however is the following: Don't attempt to fly your Seawind off of the water until you have many hours of time built up in land operations. Then, get Seawind specific instruction from someone who has flown Seawinds on and off the water.
About Porpoising:
Porpoising is the term used by seaplane pilots to describe an oscillation that can be set up under certain combinations of water conditions and pilot inputs in a seaplane. The seaplane will leap and dive on the surface of the water in a way akin to a porpoise, hence the name. If allowed to continue unchecked, disaster usually results. While it is generally accepted that porpoising is a piloting problem, rather than anything else, it is affected by certain characteristics of individual seaplanes.
When the early turbine powered Seawinds started to fly, the pilots had a tough time learning how to handle porpoising. My own opinion is that the high power available from the turbo-props (some in excess of 550 HP) could easily over-drive the airframe. On a few occasions, the plane was known to get to "bucking" so bad that the prop contacted the mid-deck. As pilots learned the right balance of power application and elevator input, these problems were eventually overcome. In other standard 300 HP piston powered Seawinds, porpoising has occurred that resulted in all degrees of submersion. Some folks have reported burying the canopy in water, but still recovering. Of course, not all have been so lucky. In part, control of porpoising in the Seawind involves the pilot successfully controlling the forces of the high centerline thrust constantly trying to push the nose down. Of course, the magnitude of this force varies with power setting.
This is a highly oversimplified and brief treatment on porpoising. There are dozens of factors that affect the condition, including wave action in the water, air and wind conditions, and just about all airframe characteristics. My purpose here is to make you aware of the condition, advise you that it is not necessarily an airplane thing, but a piloting thing, and prompt you to obtain the appropriate information and training. There are several books about seaplane piloting available. For a good list go to the Seaplane Pilots Association web-site found on our links page. One of the best books I've seen on the subject is Seaplane Operations, by Dale De Remer and Cesare Baj, English addition 1998, ISBN 0-9622159-4-5
Water Take-off:
Not unlike every individual seaplane, the Seawind has some slightly different handling characteristics than other seaplanes. The Seawind's hull is very slick. Some seaplanes require extensive nose-up trim, and a combination of up, and then down-elevator to get on step. The Seawind is different. It usually just requires normal take off trim. Dick Silva advocates leaving the trim exactly where it was for landing. After completing the take-off checklist, the controls are left in the neutral position and power is added. The Seawind will come up on-step by itself. From Dick Silva, "As the bow wave passes [under the fuselage], give it "up" elevator, and then relax the controls. It accelerates rapidly. Once on the step, lower the flaps to 40 degrees and let it fly itself off the water.
You will be flying in ground effect at [about] 54 MPH, with just the keel touching. When it breaks water, it will stay just above the surface for a couple of seconds as it picks up air speed. Then it climbs rapidly." ***
Water Landing:
Don't push the nose down. Don't carry power. With power, the Seawind may re-launch when it contacts the water. With power at idle, the V-cuff in the water creates enough drag to hold the Seawind on the surface of the water. Once the water is contacted, keep the nose at the same angle as it was at touchdown (about six degrees). The Seawind will then plane briefly until it comes off the step, at which point it settles in and decelerates to a stop.
Dick Silva adds the following. "Many times, especially when I am alone, I throttle all the way back to idle power and land on both land and water by simulating an emergency landing, you will be better able to judge when to lower the flaps to glide to the desired target landing point.
Remember, most emergency landing procedures for the seawind on land or water, are with gear up. In an emergency the only time you want to lower the gear is for an airport, highway or a known hard packed turf surface. All other emergency cases call for gear up. You are, in effect, doing a power-off water landing. Why not do that normally? The water procedure applies to soft wet grass, a swamp, a plowed field, a corn field, snow, ice, sand, (you name the rest)." ***
Rough Water:
What is rough water? The maximum wave height that can be handled by a seaplane is a function of, among other things, its length. In general, a hull that is 24 feet long can handle 12 inch waves.
The best and most complete information I have found about rough water operation in the Seawind is from Dick Silva. Rather than trying to paraphrase, I just included his text directly in the following paragraphs. You'll note in the text that Dick also refers to an occurrence described in our Hangar by Len Carlson. From Dick: "I always say, "15 inches you know you are on water, 18 inches you know you should not be there, and anything over that height, look for a lee shore or an airport." Now we know from Len Carlson, that almost anything is possible, but we do not recommend it and I am sure he doesn't either.
Before landing on water, you should make the last inspection pass low and slow to observe the water conditions.
Over the years I have learned (the hard way) that the water is 30% rougher than it looks. If you suspect it is too rough to land, it probably is.
Remember, unless it is an emergency, you do not have to land in bad conditions. There are alternatives. You can look for a lee shore. You can look for an airport. If you must land in rough water, once you have checked for wires, towers, etc., then make the pass to determine where to land. If the wind is strong you will see well defined wind streaks. Now you have to determine which direction the wind is blowing, along the streak line.
The lee shore will be calm and the windward shore will have waves. Now you know the direction to land into the wind. Land near the lee shore, leaving enough distance to take off again should you have to. I like to have at least 2500 feet.
One last caution. If the water is very rough it could impact the flaps in the down position.
Touch down as you normally would with full flaps and the nose up about six degrees at about 64 MPH indicated. If the winds are 20 MPH, you will be touching down at 44 MPH. Once you are on the water and you are sure you will not become airborne again, raise the flaps before coming off the step.
If you have the slightest suspicion that a flap may have struck a wave, stop and take a moment to check that you have not bent something. Simply open the canopy and raise the flaps all the way and visually check to see that they are even with the filler on the hull. If so, you can proceed. That will take you all of thirty seconds. However, if the flaps are not even, you just avoided disaster. NEVER, NEVER, NEVER take off with differential flaps.
You will be surprised how well the Seawind touches down on rough water. Stay Alert! As you slow down you may encounter some bouncing if the nose gets too low. I suspect that it is a result of that "old compromise." The Seawind has a fairly flat nose. I believe that the "V: shape of the center of the hull helps cut the waves. When you slow down, the wave will start to strike the flattened nose area and result in some bouncing.
The next logical question is: Why not make a "V" nose? The answer is, the "V" hull will give more drag and less airspeed.
I have landed on rough water where the waves washed completely over the canopy. I wished I had decided not to land. I was doing a demo for a guy who came all the way from Sweden and I wanted to give him a water landing. FAUX PAS DU MOIS. Do not let the pressures of the moment cloud your good judgment.
All the discussion so-far has been about landing. Making a rough water take-off can be difficult. Those of you who have seen the [SNA] video, "The Seawind Story," should recall a spectacular rough water take off. I had attended the Moosehead Lake Splash-in. I landed on the water on Saturday and came up the ramp at the display area to show the Seawind.
That Saturday night the wind whipped up out of the north, straight down the lake to the Greenville event at the south end. Sunday morning I was greeted by twenty inch white caps.
I did not know that Hank Austin, the originator of the cable TV show, "flight Line," was on the shore line. He video taped the take-off.
The Seawind took the pounding in stride, as it literally danced off the water. It is a spectacular scene, as it clipped a wing tip on the water, then the tail, then the other wind tip and back to the first wing tip. What the video did not show was that my head set fell to the floor.
If you look closely at the scene, you will see that at all times the nose is held up and not allowed to drop. This is where experience and feel comes into play. If you hold the nose too high, you will drag the tail and the drag will keep you from getting airborne. If the nose is too low it can induce porpoising... It won't take long for you to find the sweet spot.
When you start your take-off run, especially on rough water, start with the flaps at zero degree. That will keep the flaps from impacting the waves while giving you full aileron travel and control. Once on the step, lower the flaps full down, they will be clear of the waves.
On very rough water keep that nose steady and up. Be alert for a larger wave that may prematurely get you airborne with a bounce before the aircraft is ready to fly. If it happens, keep the nose up. You may be in for a bounce or two, but nothing more."
Step Taxi:
"Of course we are back to talking about reasonable water conditions. You will not be step taxiing on rough water.
The Seawind has a unique characteristic that makes it very stable during step taxi. First, you do not need full-up elevator trim. I trim it purely by feel when I am landing. When the trim feels right, I leave it where it is. After landing, I leave it where it is. When I am ready to step taxi or take off, I let it come up on to the step by itself. Once on the step, if I step taxi, I set the power to maintain between thirty and forty knots. I then tweak the trim until it is stable. Because of the tremendous ground effect, the wings want to stay level. I will demonstrate the stability by letting go, folding my arms and letting the Seawind step taxi hands off.
The Seawind does not step turn sharply because the wing tip sponsons limit the angle of bank. I have not had one occasion when I had to do a spiral step taxi to a take-off.
I can tighten the turns by dragging a sponson tip while being at the ready with the rudder pedals.
A couple of builders put a skid plate on the sponson tip, ala, Lake. Mike Bowes is one I am anxious to hear from as to whether it has made a difference in step turns and if so, is it worth the drag and speed loss?
There is much more to water flying than taking off and landing. There area many builders with much more experience than I have, with docking, sailing, and river flying.
One might think after reading this article that water flying is harrowing and dangerous. Properly done, it is not. It is always a thrill to slip smoothly onto a lake. Water flying can be very exhilarating and it will allow you to see and visit placed no one else can witness." ***