INTERNATIONAL SEAWIND PILOTS ASSOCIATION
Vol.5.No.1 Page 139 January 1998
There has been a great response to my request for a replacement. Over 50% of our membership voted and the response was a clear cut decision in favour of Mike over Paul. Congratulations Mike...sorry Paul. The decisiveness of your choice leaves me very happy. There is nothing worse than a hung jury! The decision as to the length of term was not so clear cut but the majority favoured four years...so there you have it Mike. I would like to thank you all for the kindnesses you have shown the chair and mention that we are all indebted to those listed below who made contributions to the Newsletter over the last four years.
Paul Array Dick Silva Mike Bowes Art Wild
Richard McPhee Tony Irwin Robert Greene Craig Easter
Bud Gustin Doug Karlsen Don Wolf John Kivenko
Berndt Eggert Johan Forrsblad Fred Hamilton Ulrich Esser
As many of you are aware, the freedom to stand up and be heard is not a given in every society whether public or private and it has been my interest to see that those that have had things to say be heard. Vested interests and monopoly control might be good for profits but in a research and development atmosphere they are an anathema to progress. Ideas must be tried and points of view that might seem wrong need testing; that is how we grow. We builders have had to educate ourselves in the construction process. There may be a few naturals among us but I imagine the majority have had their moments including Dick (Silver) no doubt when they felt they were going backwards but we have all matured and grown wiser in the process. I have always felt that had SNA had the luxury of developing their own prototype rather than picking up the pieces from Haliburton that their own product would have been better and our building experience easier. But then we would have had to wait two, or three years and how many of us had the wisdom. It was and still is a "love affair" with the Seawind and like all affairs it sure arouses passion sometimes and of course we must have it now !
For the last four issues I would like to generate some heat on the techniques of flying the Seawind. I am quoting I know from a floatplane expert but if there are any differences in technique you experts get in and say so, otherwise I will read >Water Flying Concepts= from cover to cover once again !
Water Flying Concepts by Dale De Remer
I always ask the applicant for a simulated high density altitude, maximum gross weight takeoff. Normally, much of the training has been done at less than the maximum allowable gross weight conditions. We simulate this by not allowing full power for the take off sequence. I feel that it is a valuable demonstration since all floatplane pilots must, at times, abort a takeoff. They should at some time in their training have had that experience. It is the attitude that every attempt at takeoff must result in becoming safely airborne that causes seaplane pilots to, at times, end up in trees.
In any attempt, the most important thing is to gain takeoff speed. That sounds pretty basic doesn't it, but I have seen good pilots humbled and a little confused when they have failed to reach that flying speed. In each of these cases the pilot failed to attain that necessary item, constant acceleration - that feeling of the body being thrust backward, at times ever so slightly, until flight occurs. Let=s review the other feelings a body can feel. They are 1. Bouncing - this is a water condition, waves etc., felt as an up and down movement on your seat. That can be stopped more or less by forward pressure on the wheel or stick. 2.Porpoise - the front of the floats are being held too low- felt as your head and shoulders move forward and back. That can be stopped by applying back pressure to the wheel or stick. 3.Bow Drag - the bows are being held too low - felt by the whole body as if brakes are being applied, or, as in less severe cases, as all forces stopping - this is overcome by a slight back pressure on the wheel or stick. As the aircraft=s speed increases, the pilot must change its attitude to accommodate the changing forces. The attitude for fastest acceleration is always just slightly nose up from bow drag. This means that in order to get that fastest acceleration, you must, at times, during the takeoff, get just a bit of bow drag so that you know where the least attitude drag is. A takeoff then is one of constantly small corrections until the aircraft is airborne.
Glassy Water Landings
The one thing that we do not want on a glassy water landing is a flare-out to a landing. We cannot flare out because on a glassy water surface, we cannot see where the surface is. With that one goal in mind we must have a procedure that makes the landing possible.
Earlier in these observations, I mentioned that the lake should be at least one mile long. It is important that our procedure fits for that length of lake. I find, quite normally, applicants taking over two miles of lake to get on the water.
We must remember that in order not to have a flare-out, we must have very little attitude change whilst on final. Let=s assume fifty foot banks with fifty foot trees surrounding the lake. In order to have little attitude change on final we will have to be quite close to the tops of the trees as we come over the shoreline - let=s say twenty five feet. This should give us one hundred and twenty five feet to reach the water. Remembering that we don=t want to land on the beach on the far side we have only about 35-45 seconds, once we've passed the shoreline to get the job done.
How can it be done? First, we must know of any errors in our airspeed indicator at stall speeds using a landing configuration of desired flaps. Secondly, we must be aware of any errors in the vertical speed indicator. These are two very important instruments for the glassy water landing.
Let=s start the whole sequence from just after the turn onto final approach until touchdown. At the start one should be about six hundred feet above lake level- this gives one about 475 feet to descend to the shoreline. At an average rate of descent of 350 ft. per minute- at an airspeed of 1.3 times the stall speed for approach configuration - one will need a minimum of one and a half miles final before reaching the shoreline.
Remember, control airspeed using the elevator and the rate of descent with the throttle. When you arrive over the tops of the trees at the shoreline, you should have gradually slowed to 1.2 of your stall speed. From that point, to the water=s surface you must descend about 125 feet within a span of 35-45 seconds. In order to get that job done, with a slow descent of 25-50 feet/min for the last 25 feet of descent to the surface, you will have to increase your rate of descent for a short time after passing the shoreline. When you are at the shoreline, decrease your power for about three seconds to a power setting that would result in a 500 feet per minute descent rate. Note we do not want to attain a 500ft/min descent rate - we want only a power reduction for about three seconds, that would have resulted, if left unchecked, in a 500 ft/min descent rate. At the same time increase your attitude to an airspeed of 1.1 times your stall speed. Then, hold this attitude and increase your power for a rate of descent of 25 to 50 feet/min. Maintain this condition until touchdown. After touchdown, close the throttle. The profile should look as in the figure below.
The Truth & Obfuscation
I would like to take this opportunity to use the Newsletter to pass on to you all the results of the letter which I sent to all ISPA members.
I did expect a few letters to come back to me with comments both good and bad, but quite frankly I was surprised at the number from whom I have had good and very supportive comments. Thanks guys, I am now convinced that many people/builders and potential buyers were appreciative of hearing another angle on this matter, one which I thought and one which was echoed in the replies, showed a more pragmatic and understanding approach to the situation. For those of you who did not write back, I hope you also saw the wisdom in my point of view and that you will act accordingly when you hear more bad (news) coming from the same source.
Now to the Newsletter. Many thanks for your efforts Dick, I for one appreciated them. For those of you who were in the tent at Oshkosh when the idea of a builders letter was discussed you may recall my comments there in reference to the problems an editor would get. Trying for a balanced output would not be easy, I feel I have been proved right.
I have put my vote for the Newsletter management for Mike Bowes, for the same reasons I stated in my letter to members, (in some of the letters I sent out it was not mentioned because they crossed with Dick=s announcement of his retirement). Mike now knows a great deal about the project and can be fairly critical where necessary. Mike has now helped several people to build their own aircraft and has flown several, so, to my mind, he has to have the best knowledge of the pitfalls and promises. With this excellent hands on experience of building and flying he would be able to tell the differences between each aircraft and why they exist. He is also a sound, honest and stable guy. In testimony, witness the lovely aircraft belonging to Walter Baron he supervised in building.
I have thought of adding my say to the ISPA letters in way of showing the truth in the uncontested input to them in an attempt to further counter the surfeit of rubbish which in the past we have been fed with. As I said in my letter, it is not all lies and innuendos, but it is a very cleverly disguised mixture and to that end has been successful in making people listen, but sadly, several have, in the absence of information to the contrary, believed. Again (an example of) the vicarious minority taking over from the normal reality of pragmatic folk.
If I called my input "The Truth Letter" or similar, would that be too strong? It would comprise actions and facts to dispute the one sided version you have received over the last few years (and) I would also reluctantly have to add a bit of hearsay. This I would not relish, as it is not my want to do such, but on the assumption that "where there is smoke there is fire" I would offer to you the many snippets of information that I receive from many third parties in this manner. I would obviously vet them and try to check for their authenticity and veracity where possible. I would make it known that they were from other sources and the people concerned would not be named, they would be anonymous. I quite see and understand that many people do not want to get involved in these matters, but they are happy to tell me this and that where they have witnessed the goings on behind the scenes. As mentioned in my letter I already have many of my own first hand knowledge items which I have not yet disclosed.
Just one little snippet in this entry. We were told that the second turbine had flown approximately fifteen hours with no problems. My Floridian contacts tell me otherwise. How about the elevator connection redesign problem. Bystanders were sure it would end up in a pile! No comment made of this near catastrophe! Two aircraft built at the same place, both had elevator construction problems. One the above, hearsay, but the other I have witnessed first hand. One would think that a professional builder would benefit from his mistakes and take care to learn that he would not repeat his miscalculations. I get the impression that such an input, as the above from me would be advantageous I will go ahead.
Do not forget Oshkosh this year. I hold good on my earlier statement of a ride in the Concorde, where there is a seat available, for the winner of some sort of raffle at the show. I have finally got its charter rate down far enough and Tom Poberenzy has at last given the go ahead for its arrival this year. All the best everyone for 1998.
Mounting the Stabilizer to the vertical fin is one of the more important assembly steps in that it will have a direct influence on how the aircraft flies and trims. I have built four to date; here are some observations. Level the stabilizer to the wings. I use a transit to accomplish this and cross-check with a water level. Set the stabilizer perpendicular to the aircraft centerline. This can be easily determined by stretching a strong string from a forward point on the aircraft centerline back to the leading edge tips of the stabilizer to confirm an equal dimension. Negative 2.5 degrees angle of incidence (for 300 hp Lycoming) is set with a Smart level using the template from the Manual. It is a simple matter to draw the symmetrical chord line on the tip of the stabilizer and check that, too. Check both ends. If there is a slight difference, indicating a twist in the stabilizer, average the readings and set it accordingly.
Check the gaps between the mating surfaces of stabilizer and vertical fin and pad the bolt hole areas with 7781 >glass. I take care to mount the stabilizer with special attention to making the lower surfaces line up as well as possible. This minimizes the overhead work of filling and fairing in the adjacent surfaces. You all know that overhead work is brutal. Keep the grossest mismatch of surfaces ion the topside as much as possible where it is much easier to deal with. I install the four dash six bolts and then I also lay 2 ply of 7781 bid all around the entire seam between the stabilizer and the tail. When faired in and painted, the seam is eliminated, resulting in a beautiful one-piece look. Another obvious benefit is added strength at this crucial joint. Call me if you have questions.
A Lightweight Rudder for the Seawind 3000
The new rudder has been shipped to the sponsor for testing. We will have the results of that just after the first of the year. For now I would like to bring you up to date in the event you have not been following our web site for the updates.
What did we do to make it lighter? Fabricated the rudder from carbon graphite. Used smaller inspection panels. Moved those panels forward one inch closer to the hinge line. Moved the mounting base for the MAC servo forward of the hinge line. Bored holes in the ribs. After the fabric was wetted out we removed any excess resin. All the parts were either press formed or Vacuum bagged and peel plied. Used nut plates instead of nuts. Fabricated a counterweight that more than doubles the moment arm. Used a smaller hinge for the trim tab. Spars and ribs for the trim tab made in the mould (no cutting or bonding). Separate tools for trim tab, ribs, servo mount etc. Heat formed the foam to eliminate any joints.
The result of all this is that the rudder before counterweighing only weighs 14# and to counterweight it 100% only took an additional 7# so that is a total of 21# ready to install. The SNA rudder I have here counterbalanced to 80% weighs 30# Others have told me theirs weighed as much as 34#. Please understand that there are slight variations in any rudder made from composite materials.
What other things did we do to improve rudder design? We made the rudder wider than the vertical fin, which has the same effect as vortex generators by getting the rudder back into energized air. We sealed the top and bottom for safety and aerodynamic reasons.
What comes with the new rudder? It seems to me that people want our parts to be as complete as possible. So the new rudder will come as complete as we can make it without actually installing on your aircraft, right up to filing and priming. The parts, rudder and counterweight, pulleys and brackets, new upper fairing, attaching hardware and installing instructions.
What do I have to do to install it? Replace your existing pivot hinges, install two additional pulleys on the elevator cables, mount your MAC servo, install a new fairing on top of the rudder, mount the rudder and counterweight. The actual instructions will be placed on the web site as they become available.
How much does it cost? The tooling alone to make the first rudder cost more than $4,500, The production units will be priced at $2,800.
What does all this mean for my aircraft The rudder weighs 30% less. The empty weight C. of G. Or your aircraft will shift forward 0.4 inches, or you can take 10# from the nose compartment of your aircraft and have the same C. of G. With 19# more useful load.
What does the new system look like?
Carbon graphite and the future. This seems the material of choice for new designs. Everyone thought that as more people used graphite the price would go down and it has when compared to ten years ago. Recent trends in the market have driven the price up due to the unavailability. So when you find some material the price can be quite high. I feel this will surely affect the cost of our products in the near future.
Finally, what=s next? Fully enclosed main gear doors.
The most rewarding part about building a Seawind is the creative people you meet. For example just look at the variations in the design of the spray rails alone. I think I=ve run across at least eight different designs now. I guess one of those designs is probably the best, but does that make the other designs bad ? I don=t think so ! I recently read the biography of Bert Rutan, one of the great designers of our times and had this concept reconfirmed in my mind. The book told of how one of Rutan=s builders was complaining about all the changes he was making in his design of the longEZ. The builder asked "when are you going to finalise the design?" Rutan=s reply was Never! He said the reason for this was that his goal was to improve the design not finalise the design. One Seawind builder I know puts this into perspective using the automobile as an illustration. What if the Model T Ford had not evolved into what we have today ? The Model T was not a bad design, it was the first.
We as builders must remember that the Seawind is a truly revolutionary aircraft. In fact I would venture to say that its futuristic look is one of the things that appealed to most of us. O.K. the aircraft is heavy and maybe it does no go 200 mph, but let=s look at what it does do. It is still faster than any other four place amphibian around (and you can carry four people - you just have to carry a little less fuel ! The cabin of the Seawind is more spacious than any I=ve seen and we all know those looks are important to us. In conclusion let me say that the way that I would like to look at my products is that they are evolutionary steps in a revolutionary aircraft.
We recently put a set of our Lightweight ailerons on a Avery vocal@ builder=s aircraft. These were the production version of our already proven prototype. We made some small changes which had significant effect. After we made the prototype units we knew what the counterweight requirement were so on the production units the weights were placed in the mold and bonded in place. This allowed the counterweights to have the maximum moment arm. In addition, we knew the exact position we would trim the trailing edge so instead of putting a lot of milled fibre to seal the trailing edge we made the joint very exact and placed only the required amount of adhesive. One builder had reminded me that any weight in the trailing edge must be counterweighted by a factor of eight due to the moment arm. The effect of these two tiny changes reduced the weight of the aileron by 2 pounds as compared to the prototype aileron and 4# as compared to the SNA aileron. Note: all measurement taken from left aileron right should be even better (?)
On the test flight our "very vocal" builder had expressed concerns about the high winds just before takeoff. Myself, being raised in west Texas could not understand what the concern was all about as the hanger walls were not even moving yet ! I could not have picked up a better demo program though. Just as we lifted off we caught a gust on the left side and our "vocal builder" cracked in the usual amount of aileron. The first words out of his mouth was "Whew these things really work !@ I hope we can talk him out of a pilot report in the near future. To see some of his comments see www.seawind.net. The installation took about three days.
Some things I learned from the installation: 1.Corrosion X is an excellent product for lubricating the mixer system. 2. You can make an external stop for the flap actuator from 0.25" aluminum where the front is attached to the forward attach point and the rear has (a) slot where the forward edge is in the "up" position and the rear edge is in the flap "down@ position.3. The bent rods in the mixer are still getting bent due to the rear fork jamming against the forward edge of the flap interconnect arm. Give it some clearance or put on rod ends and move the rods to the outside. 4. The bushings in the slider (are) held in only by friction can still pop out and cause a possible jam. These should be secured with a drive rivet or drilled and taped for a #4 screw or something. Locktite is just not good enough. As these are oil tight bearings and are oil impregnated acting as a release agent.
C-FWFA - A High Performance Aircraft.
We have our Certificate of Airworthiness. at last, but with our climate not much activity is planned for the next four months.
Canadian builders please note. In the course of Certification in Canada it appears that this aircraft must be classified as a High Performance aircraft. In these circumstances the pilot needs a minimum of 200 hours flying time to qualify for the rating. I believe that includes training time but in my case I will need another seventy flying hours.
Jack Ardoyno, 11037 N Robin Lane, Hayward WI 54843 Ph:(715) 634-2984
Fax (715) 634-7246
Roy Elsworth, Box 3,Beaver Island, St. James, MI 49782 Ph:(616) 448-2433
Mark Kennedy , 355 Maxwell St. Sarnia, Ont. N7T 5E1 Ph:(519) 383-7743
R. F. Pete Petersen, 5855 Midnight Pass Rd #307 Ph:(813) 349-3165(H)
Sarasota, FL 34242
J. M. (Mike) Bowes1508 - 18th Avenue Drive East, Ph:(941) 723-0255
Aviation Inc., Palmetto, FL 34221 Fx:(941) 723-0198
THE WATER LOOP
This is a common yaw stability problem and is related to the ground loop on taildraggers. This occurs when their point of rotation on the ground (main wheels) is forward of their centre of gravity. If the flight path is skewed on landing then the main wheels attempt to lead the aircraft in the direction it is pointed but the mass wants to keep going straight down the runway. This results in a couple that makes the tail of the aircraft want to lead the parade! Therein lies the secret of the docility of tricycle gear aircraft (so long as the nosewheel is stable). All that is needed both on land and on water is that the centre of gravity be forward of the centre of rotation!
The seaplanes centre of rotation in the air is its centre of gravity on the water however it is the centre of the wetted undersurface of the hull This is difficult to visualise as it changes with the speed and attitude of the aircraft as it settles on the water. The main thing to remember IS TO KEEP THE CENTRE OF ROTATION AFT OF THE CENTRE OF GRAVITY. Keep it aft, period, until the aircraft has slowed and settled off the step.
To drive home this point I have occasionally told my students that Athe water rudder=s main purpose is to be landed on@. Actually an ideal attitude for landing is to touch the step and the heel of the float simultaneously. When contacting the water in this attitude the centre of gravity is well forward of the centre of rotation so the plane is directionally stable.
If the plane is landed in a nose low attitude (airspeed is too high) the water is contacted forward of the C. Of G.. The water loop starts with a strong yawing moment which on veering rapidly produces centrifugal force which with the increasing but oppositely opposed horizontal component of lift rolls the aircraft. Centrifugal force, momentum and the horizontal component of lift all team up to cause a wingtip to contact the water at a low angle of attack with ultimate stability the end result after a brief ride during which the pilot, passengers and other contents are subjected to abuse something akin to the abuse a rat gets when shaken by a terrier !
This is why glassy water landings, which are done at higher than normal landing speeds, are done with no or minimum flaps. Full flaps produce a more nose down attitude for a given airspeed.
To stop the water loop once started, the pilot must shift the centre of rotation aft, quickly behind the C. Of G.. This is done with up elevator which will raise the nose, which will shift the centre of rotation aft or cause the aircraft to fly again if the airspeed is sufficient.. There just isn't time to add power, unless the aircraft becomes airborne in which case power may be needed. Only a nearly instantaneous elevator input will do the job and then only if the water loop conditions are not too severe. The best management of this risk is prevention. Keep your nose up.
Yaw stability on the water at slower speeds is important, too, especially if there is a brisk wind. Taxiing downwind must be done with nothing more than minimum power so that the turn upwind can be done at the lowest possible speed to avoid burying a sponson. Keep the water rudder down so that the rate of turn can be controlled.
Excerpted from De Remer=s "Water Flying Concepts@ Ch 9 Stability on the Water.
Volume 5 Number 3, May, 1998
Volume 5 Number 4, July, 1998