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Thread: Norm's Flying Boat UL Flight Test Progress

  1. #141
    Norman Langlois's Avatar
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    This is a copy of a email I sent to a yacht designer.


    I have an update for you and another request for your opinion.
    I did rework the rear floats. they came out well. Before I took the plane for testing I did a weigh in. the plane had become extremely over weight. to continue to fly would be a violation.
    I decided to go forward with a new hull to attempt a severe reduction of weight. I need to get down from the original main hull weight of 45lb or 20.5 kg to 20 lb or 9.5 kg
    That is only to show you how much my options are now minimized.
    I n review of the last takeoffs I notice the plane uses only the same area for planing as it does at static that equates to 12.5 sq Ft or 1.161 Sq M
    Only the angle of attack changes and the resulting lift generated at 22 MPH or 19.1 knots this is the speed at which the plane reaches lift to gross weight.With me as the pilot that the gross ,equates to 474LB or 215 kg at the max allowed US FAR. 103 -7 under which I must fly max empty weight is 304lbs. or 138.1kg. this does not have to include pilot weight. At 24 knots the plane reaches a gross lift of 560 lbs or 254 kg
    24 knots is also a requirement this is the required power off stall not to exceed limit.

    The area required to float is 7.5 cubic ft or .20105 cu m the area in square presented for planning is12.5 sq ft since the total displacement is shared with the rear system only the forward area is used to get lift to plane.
    Is there an optimum area for a given weight that you know of . Or a table for calculating?
    I'm forced to use the smallest area and use a shape that offers structure. I am considering a simple wedge with tunnel tri hull like some of the first tunnel three hull pickle forks.

    I am a bit stuck for ideas on this. The imposed limits choice. A simple hydro plane has not enough structural shape. I think I need the tri hull for structure?
    Any input will be appreciated. the project is stalled
    regards Norm

  2. #142
    Norman Langlois's Avatar
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    The above is for info . It does not cover all the most pertinent . Here a some pictures to contemplate the previous solutions taken and the desired result achieved.
    Name:  hulljig1 025.jpg
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Size:  95.7 KB This the original bottom later modified in 3 separate attempts to achieve a satisfactory hydro dynamic behavior. A hump at the forward incline was producing severe bow drag. After removal flying was easier, but still elusive ,without a head wind. These conditions were before the elevator control limit was discovered. So many discussions and suggested solutions before this was found out. Name:  127_0207.jpg
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Size:  95.7 KB Still searching ,I cut away the most important bottom feature the slight down curve at the stern. Name:  IMG_0164.jpg
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Size:  92.6 KB This cut made getting on plane impossible with the limited elevator still not discovered. I next raised the rear floats also a disaster. This resulted in no balanced control and a ripped up wing. Then I put the rear floats back approximately.where they were. and added back an enhanced , stern curve. Name:  127_0210.jpg
Views: 84
Size:  95.8 KB With this added back on there was no more problem getting up on plane. It now could fly with any reasonable run but still liked a slight head wind. I gave myself a long think tank . Muddling over all the history, remembered a better time getting off the water . the suggestion that I did not have enough elevator authority . made me look into that linkage . I had made a second connector that was actually,longer. I removed and the short one and installed the long. All the take off problems were gone flight in any condition even down wind.

  3. #143
    Norman Langlois's Avatar
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    Now with good take off behavior . One thing kept creeping back into my mind,why did the plane have increased take off difficulty each time on the same day of use. I suspected a few things ,weight gain,or engine temp. It may have been both or just the one, water weight gain.

    So now I must make a new hull . What have I proven to all my skeptics if only one thing an Ultra light does not share the same needs of general aviation. No step required, it flies off . It definitely could use a better shaped hull , maybe not anything like I was thinking. why not a simple planning hull like a hydro plane . these aircraft are not meant for use in rough water or windy conditions that create rough water. displacement required is 7.5 cu. ft min. a surface equal or better than the existing 12.5 sq ft presented before and running on at planning to lift off.

    The final requirement is this must not weigh more than 20 lbs. I need a few lbs for adjustments to redistribute the weight to obtain balance of the CG. expect to move any hull forward 16 inches and like wise the pilot. those 10 lb ruder pedals will have to become hinged foot pedal with pulley.

  4. #144
    Norman Langlois's Avatar
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    Sorry for the long story. Anyone considering should remember the plane has a very thick USA 35 modified airfoil. This wing produces lift from the get go unlike many thinner wing designs that reach flying speed before rotation . This plane becomes lighter as each MPH is achieved. and reaches balance of 510 lbs with a 180 lb pilot and 30 lbs of fuel at or about 22 mph.

    This to point out that the hydro dynamic drag is not linear. With the surface area rapidly reducing.
    As the latest video shows that very poor hull bottom still gets the job done, in 6 seconds. That's time after planning is achieved. The first 6 seconds can be improved with design . That is now the great big problem to do it with the least amount of weight the better.

    Lastly any improved hull will be a 58 lb or more reduction from what that last video showed the plane do
    Last edited by Norman Langlois; 07-05-2018 at 05:17 PM.

  5. #145

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    Flat bottom floats have the least hydrodynamic drag. Your hull is almost flat bottom, so should be fine on calm water.
    The early homebuilts from the 30’S had flat bottoms.
    A guy in my RC model club built some flat bottom floats after watching mine fly off so well. His worked fine and then he wanted to experiment and carved a tunnel hull. It wouldn't lift off with the deep tunnel hull. It just adds water drag with no water lift.
    Several float design articles in the Flying and Glider pamphlets from EAA.
    Last edited by Bill Berson; 07-05-2018 at 08:41 PM.

  6. #146

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    Norm, see if this link to Pietenpol Floats.
    Edit, doesn't link.
    Maybe someone has a copy of Pietenpol Floats article to put here?
    Last edited by Bill Berson; 07-05-2018 at 09:42 PM.

  7. #147
    Norman Langlois's Avatar
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    adding more photos to define this subject. Name:  127_0214.jpg
Views: 77
Size:  97.3 KB notice the hump removal defined here and the respective influence of that stern plate addition. That item is not understood by me . However it is very important to how this hull flew off the water. this next photo is trying to show the required thickness of the hull as a whole . In reference to the static photo (previous posts) draw a line through from the blue paint line to the bow this is the needed area I determined at 12.5 sq ft. the depth and cubic of same to be 7.5 cu ft for displacement. Name:  127_0211.jpg
Views: 73
Size:  94.7 KB

    Now The whole plane float design change would represent a much bigger problem of balance . Such as twin floats. With no rear rear system. I personally do not wish to fly a float plane with its high center of gravity and potential for a flip over. Though it does have a higher weight allowance. Twin floats would be very difficult to support and build with only 60 lb allowance.
    My existing air frame is also to heavy to add structure.
    The shortest route and simple fix is to just create a new main float. This could be done.Yet balance is still a problem . The shorter lighter hull is not enough to balance the aircraft. The pilot must move forward also.
    That will put more importance on the planning surface required in the high speed taxi.( watch one of the last take off videos the one that starts from the beach) Take notice of the hull at fast taxi . Much of the forward hull is not needed its just splash protection .A slight up curved surf board would do as well.
    A tunnel hull shape is not required a V hull is not required . In my humbled opinion not much change other than to do a better transition from static to fast taxi planing surface. And remove any potential bow drag shape. Maybe a flattened spoon bow transition to a narrow flat bottom stern with that stern plate or just a slight down curve . The down curve ( because it seemed to play an important part for getting up on plane) the plate because this helps with separation and fly off.

    One other desire would be a shape that also reduces the initial bow wave. Would a flat forward hull ,not unlike very early hydro planes do. I do mean early designs, before the forward sponson jet boats.
    Last edited by Norman Langlois; 07-06-2018 at 08:30 AM.

  8. #148
    Norman Langlois's Avatar
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    I got my hands on a rel big foam block. 15X48X192 . So I have been at work making templates and carved out a rough core for a new hull. this core weighs in at 15.4 # still and needs more removed. Name:  20180715_153629.jpg
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Size:  80.4 KBName:  127_0220.jpg
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Size:  90.1 KBName:  127_0223.jpg
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    Compare this profile to the static photo and you can see where im going with this.
    With the low density foam I wish to keep a thicker forward hull , while eliminating any upper cockpit and keep it open . I'm not sure I can afford to. I currently have a 32# total and need to have some other aluminum structure added for moving weight forward.
    Last edited by Norman Langlois; 07-15-2018 at 03:50 PM.

  9. #149
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    After some carving I have the weight down to 12.4 still in rough needs some more.Name:  20180720_144438.jpg
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Size:  97.3 KB I'm not sure if many out there want to see how I get the foam cutting done. Its sometimes very difficult ,I have to make tools . There are some out there one can buy. The ones I saw would just not do. Even for this one I had to borrow a real hot wire power supply. Because of a few of my tools being made from 1/16 S/S tig wire my power supplier just burned up. It was just a fan dimmer switch, couldn't handle this one. Even with the real thing the cording needs to be heavy duty. Or time outs are required. these two tools are what I needed to go deep and cut cavities. The 1/16 S/S wire will hold a shape allowing contouring . Name:  20180720_125836.jpg
Views: 49
Size:  80.1 KBName:  20180720_125825.jpg
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  10. #150
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    Today's work. the tool I used to cut the concave. Name:  20180721_110019.jpg
Views: 44
Size:  87.7 KB the results Name:  20180721_112315.jpg
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Size:  94.3 KB After some sanding and blending Name:  20180721_142712.jpg
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Size:  88.5 KB lastly I made cuts to the bottom . I hope I have made a good choice. Name:  20180721_153332.jpg
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Size:  90.6 KB When finished, I see this having a behavior that is positive. Water first push up a forward bow wave, the center having a slight cutting hull . The rest would act like a chine. Water pushing up and as the hull rises the after portion is riding on the center portion where it transitions to flat ,not unlike my first hull. The contour should enhance the otherwise week foam hull. This is much lighter than the old hull. It is thicker , wider and actually has more displacement. the core now weighs 11 lbs.
    Last edited by Norman Langlois; 07-21-2018 at 02:26 PM.

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