Laurent Fabre’s design ideas

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cluttonfred

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Laurent Fabre is a French light aviation enthusiast who likes to explore ideas for LSA/microlight/ultralight aircraft through models and full-scale mock-ups. None of these have been developed into buildable designs but they are food for thought.

You can visit his blog here (some of the titles are in French but the posts are in English). I am sure he would welcome feedback in English or French.


Latest concept (electric power):

9C148816-B2F2-4645-90A8-D9DC1701FC4E.png

Experiments in wing folding:

5E71B592-5072-47D1-B1EC-064F269D05FC.png

Earlier iteration full-scale mock-up:

 
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He posted a number of things to a Facebook group I'm a part of. I found his wing-folding mechanism terrifying, and a number of more knowledgeable people pointed out to him its flaws. He was unfazed, and seemed not to have considered that structures respond differently in shear, tension, and compression. But yes, he is enthusiastic.
 

cluttonfred

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Well, “terrifying” seems a bit melodramatic. These are mock-ups to work out geometry and layout, not anything actually intended to fly. I thought his earlier design with the wings folding straight back and the triple tail was quite appealing, though I would prefer a separate trailer over a bolt-on trailer hitch.
 
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Well, “terrifying” seems a bit melodramatic.
It was not clear from the Facebook presentation that what we were seeing was a mockup. In that context, I don't see anything melodramatic in "terrifying". If it was a mockup, that's a lot better, but it's still concerning that he's mocking up structures that go beyond TLAR to "that don't make no sense."
 

cluttonfred

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It was not clear from the Facebook presentation that what we were seeing was a mockup. In that context, I don't see anything melodramatic in "terrifying". If it was a mockup, that's a lot better, but it's still concerning that he's mocking up structures that go beyond TLAR to "that don't make no sense."

Wow, I don’t know what FB group you’re talking about, but if that’s the reception an enthusiastic older guy got when he shared his ideas, no wonder he didn’t take up my invitation to join this forum.
 

cluttonfred

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The challenge with something like this is getting enough wing area in a package small enough to fold up easily. I usually shoot for a 20’ ISO shipping container which translates to about 18’ L x 7’ W x 7’ H once you consider door clearance. That’s pretty tight for enough wing area for Part 103 (though a biplane with a high lift airfoil might work) but absolutely doable for LSA or microlight limits.
 
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Wow, I don’t know what FB group you’re talking about, but if that’s the reception an enthusiastic older guy got when he shared his ideas, no wonder he didn’t take up my invitation to join this forum.
Could it be that I'm thinking of someone else? The guy I'm thinking of came in trying to sell the concept and what he had constructed, if I recall correctly, and I would have sworn it's the same design and URL; it was something about ailes repliables in the url. Maybe I misunderstood what he was trying to accomplish, but I wasn't the only one, if so.

Now I'm concerned that I participated in a big misunderstanding.
 

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I’m not big on how the tail boom seems to be attached but if that cabin structure is strong enough get a load of how big the entry door can be!
1656813302528.png

Just imagine if it was controlled with a side stick on the right and you get in on the left by just sitting down and swinging your legs in. It’s so much more civilized than pretty well anything that’s come before it. It may seem like a minor detail but I think those kind of quality-of-experience items can make a big impact on light aviation.
 

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Could it be that I'm thinking of someone else? The guy I'm thinking of came in trying to sell the concept and what he had constructed, if I recall correctly, and I would have sworn it's the same design and URL; it was something about ailes repliables in the url. Maybe I misunderstood what he was trying to accomplish, but I wasn't the only one, if so.

Now I'm concerned that I participated in a big misunderstanding.
Of course I dreamed of building a real airplane and flying it, and you were right to warn me and point out all what was wrong. But first I wanted to show how my folding system worked and the interest it presented and no one convinced me that this system was not viable. See my last article:
 
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Of course I dreamed of building a real airplane and flying it, and you were right to warn me and point out all what was wrong. But first I wanted to show how my folding system worked and the interest it presented and no one convinced me that this system was not viable. See my last article:
Yes, Matthew has pointed out to me that I misunderstood your intentions, and mistook your mockup for an airframe you not only intended to fly but to sell. I'm glad to hear I was wrong, and hope you continue your explorations and listen to the advice of people more knowledgeable than I.
 

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Yes, Matthew has pointed out to me that I misunderstood your intentions, and mistook your mockup for an airframe you not only intended to fly but to sell. I'm glad to hear I was wrong, and hope you continue your explorations and listen to the advice of people more knowledgeable than I.

What I wanted to sell is my invention. I wanted Mr. (or Mrs.) Cessna or Piper to offer me 1 million dollars to have the right to use it. The worst is that I did really hoped that!
 

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I’m not big on how the tail boom seems to be attached but if that cabin structure is strong enough get a load of how big the entry door can be!
View attachment 127301

Just imagine if it was controlled with a side stick on the right and you get in on the left by just sitting down and swinging your legs in. It’s so much more civilized than pretty well anything that’s come before it. It may seem like a minor detail but I think those kind of quality-of-experience items can make a big impact on light aviation.
I'm not sure the cabin I designed is stiff enough. It will probably be necessary to reinforce it and then perhaps the access will be less easy? It needs to be seen by someone competent
 

jedi

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Well, “terrifying” seems a bit melodramatic. These are mock-ups to work out geometry and layout, not anything actually intended to fly. I thought his earlier design with the wings folding straight back and the triple tail was quite appealing, though I would prefer a separate trailer over a bolt-on trailer hitch.
The trailer versus tow on the landing gear is a common issue and the result is a strong function of how far and on what roads the towing is intended.

I would like to hear comments on a middle solution that I have not heard discussed before.

Keep the trailer hitch on the aircraft tail. Build a stub trailer to mount to the airframe landing gear for road transport only, similar to the two wheel rental trailer for automobile towing where the front wheels of the towed vehicle are driven up on the short trailer and the rear wheels of the towed vehicle follow behind on the road surface.

In this case the entire aircraft would be supported on the two wheel stub trailer with the aircraft structure connecting the trailer tongue with the wheel unit. The tongue would fasten directly to the wheel unit for towed transport without the aircraft and provide compact storage of the road vehicle components when not a part of the aircraft storage. The stub trailer would also allow a lower overall height as compared with the typical aircraft on a boat trailer to allow for storage in a single car garrage or in a reduced hangar space.

The two wheel stub trailer would have highway wheels and suspension suitable for typical highway speed road transport on typical road surfaces.
 

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I designed this landing gear so that the plane is suspended when it is on the road but without much variation in track, to maintain good stability. It's not made to drive 1000 km at 130 kmh behind a car but to go from its garage to the airfield at 80 kmh maxi speed. For longer journey your solution would be better
 
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