Light Touring Amphibian - LTA-9

Discussion in 'Bush / Float flying' started by Woodenwings, May 12, 2019.

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  1. May 17, 2019 #21

    Woodenwings

    Woodenwings

    Woodenwings

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    BjC:

    Reliability: I am confident that the electrical propulsion systems are more reliable mechanically. This is just a byproduct of electric. The cost of these systems is low..Ishmael and will probably get cheaper in time whereas petrol power, while being beautifully well understood and made by so many...is complex and prone to many kinds of possible failure modes. I also see the cost climbing...and while it does the public will gradually point "enviro-fingers" at even the classic warbirds who kept us safe in the past. I'm going to give electric a try...but hedge by bets with a radial.

    I may want to make very long flights. Time will tell. A radial is a perfect a compact attractive choice...except for low rpm vibration. The mount will have to be more substantial than electric. Infact...I have considered making the entire wing swappable (electric and gas). All gas related controls like throttle and mixture and carb heat...and fuel quantity could be electronically controlled/monitored in the cockpit. It's more a conversation of could over should. Weight would be comparable electric or gas...except gas gets lighter as you fly.


    Riggerrob
    CG for flouting with wings folded.
    I think the wings will have to be extended..or at least one wing. I think trying to add buoyancy for stable folded wing water use is a little too much of a challenge if the wings folded over the top it might be possible...and upright at 90 deg. may turn into a "sail-plane"...is that name already in use???

    Wing sweep like an f14 would keep cg in place while swept...???
     
  2. May 17, 2019 #22

    Riggerrob

    Riggerrob

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    Wing-sweep - like a Grumman F-14 Tomcat would keep the roll centre of gravity the same, but shift the C. of G. towards the tail, requiring increased reserve buoyancy (in the aft fuselage) to prevent the tail from sinking.

    As for roll stability - while folded - we were hoping that your sponsons would have sufficient span (e.g. 8 feet) and sufficient reserve buoyancy to prevent rolling over.
    Wide sponsons also provide wide main wheel span for landing in cross-winds.
    Yes, we understand that you primarily want wheels as beaching gear.

    The ultimate reserve (roll) buoyancy is the Australian-build, Catalina ultralight with a hull that resembles a Zodiac (inflatable boat) with a V-shaped centre hull. The hull is all rigid plastic, but it resembles an inflated rubber boat.

    Warning!
    Thread drift!

    Some of us have speculated about installing inflatable hulls on our fantasy flying boats. Only helicopters have succeeded, but their rapid-inflate floats are strictly for emergency ditching in the ocean after engine failure.

    Other speculation allowed reducing width (to the 8 feet needed for trailering) by deflating a 10 foot wide boat.
     
  3. May 17, 2019 #23

    Woodenwings

    Woodenwings

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    Of course you are correct with aft wing CG movement. Sponsors may be 8nder the wing and offer some stability. I imagine wing folding taking place near the point where wheels will no longer hold up the machine. An inflatable skirt like an airmatress. Low pressure high volume could work. If a small electric pump or fan (like a Christmas lawn ornament) was able to be inflated and then sucked back into a stowage location it would be cool. Problem is weight. I feel like there is enough inherent complexity already.

    Folding on the trailer is probably the way to go. I may have to figure it out in good time.
     
  4. May 19, 2019 #24

    Woodenwings

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  5. May 19, 2019 #25

    Woodenwings

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  6. May 19, 2019 #26

    BJC

    BJC

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    Help me understand the purpose of the folding wings.

    Here in Florida, you will need a special permit to transport the plane, will have to pay, will be severely restricted as to when you can transport it, and likely will need an escort.


    BJC
     
  7. May 19, 2019 #27

    Woodenwings

    Woodenwings

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    In canada you trailer what you like as long as it isn't more than 3.7 meters wide and 25 meters long..mass for a plane is less than the trailer. My space at the side of the house is less than 3.7M or 145". So the common method in Ontario is to tilt the thing on its side until it fits. I can probably squeeze about 3 feet out of the width and tilt it like the boats do without a problem. If the props get too close I will relocate them. Struts can be detached etc. My problem...no one else's!
     
  8. May 19, 2019 #28

    Woodenwings

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    I I'll have to get more clever to get it to about 6 to 10 feet folded. The last set of drawings just showed the grumman style fold. It was just to see what geometry needs to happen. 45deg x 30deg as it turns out. Props may need to move to pusher config. Aka piaggio propeller location and folding joint may need to occur close to the fuselage.

    Will get around to exploring that later.
     
  9. May 20, 2019 #29

    Riggerrob

    Riggerrob

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    Which raises the question of whether electric motors are light enough to fold along with outer wing panels??????

    The distance between crankshafts will probably be in the 80" range (based upon the 65 to 72" diameter propellers installed on Rotax 912 engines) .... meaning 90 or 100" total span across the engine nacelles.

    Have you considered hiding fold mechanisms inside engine nacelles?
    This would allow longer hinges .... reducing point-loading on hinge components. It would also allow you to separate flight loads from trailering loads .... meaning that you could have detachable spars ..... and carry trailer loads on hockey pucks (rubber cushions). This reduces the risk of pot holes cracking spars. Glider pilots warn us that pot holes can do more damage than flight loads.

    Finally, have you considered pivoting the entire wing plank to lay along the fuselage centre-line?
    This would confine fold mechanisms to cabane struts and simplify wing structure.
     
  10. May 20, 2019 #30

    Dillpickle

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    As if a Pby and Air-cam had a rebellious teenage baby...
     
  11. May 20, 2019 #31

    Dillpickle

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    ...works on project for ten years...gonna take another ten..has no time, lol
     
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  12. Jun 10, 2019 #32

    Vlad

    Vlad

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    Dear Woodenwings, I have been into light aircraft design for about 8 years (well, on and off). All this time I was looking for like minded people/friends from the area. I am also working on an amphibian plane of my own design and the fact that I found a person who designs his own plane from scratch, (not building it from a kit) and on top of that his plane is also an amphibia, is a miracle! Countless attempts to find someone like you by attending all kinds of homebuilt aircraft clubs were unsuccessful. The stuff you are doing and have done so far is amazing! Unfortunately I am not at that point yet, but have done a lot too (performance calcs, aero/hydrodynamics, surface modeling, CFD etc.). Is there any chance we could make a contact please? I don't find it very convenient to exchange information right here. Please reply and I am sure we could share a great deal of knowledge and ideas. My e-mail: ishi4Nee@hotmail.com

    With hope

    Vlad.
     

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