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Merlin

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Nov 17, 2020
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43
My name is Merlin, i'm 32 and currently designing my first airplane, it is inspired by Milholland's Leagle Eagle but in two seat version.
the idea is to build an airplane for under $3k that won't take me years to finish, it should take around 6 months to build.

I have already completed the welded chassis in SolidWorks and made sure there were no weak points, however i'm having problems chosing the proper wing spars.
Simulation of wood or carbon fiber on Solidworks is neither easy nor particularly accurate considering the properties of the material. Aluminium strenght to weight ratio doesn't seem ideal.

I'm a bit stuck at the time and i would appreciate some advices.

thank you :)
 

mcrae0104

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Oct 27, 2009
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3,647
Hi Merlin, and welcome to HBA. Carbon fiber is above my pay grade, but you can find wood analysis methods in ANC-18, written long before anyone dreamed of simulations and FEA and such. Please consider starting a build log thread, as I'm sure many folks would want to follow your project.
 

Merlin

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Nov 17, 2020
Messages
43
I found some custom size rectengular carbon fiber tubes on Alibaba for a verry decent price but i don't really know if i can trust it.

my second option was using Douglas fir but its allot heavyer then carbon fiber.
 

Turd Ferguson

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Mar 13, 2008
Messages
5,473
Location
Upper midwest in a house
however i'm having problems chosing the proper wing spars.
Simulation of wood or carbon fiber on Solidworks is neither easy nor particularly accurate considering the properties of the material. Aluminium strenght to weight ratio doesn't seem ideal.
Aluminum wins hands down in strength, weight and cost but it may not fit in with your wing design scheme.

Leonard Milholland built a 2-place, side by side version of his airplane.....is yours close to that?
 

Merlin

Active Member
Joined
Nov 17, 2020
Messages
43
Fisher Aircraft, among others, uses plywood and solid spar caps. Light and easy to build.
Where can i find more informations about it?

Aluminum wins hands down in strength, weight and cost but it may not fit in with your wing design scheme.

Leonard Milholland built a 2-place, side by side version of his airplane.....is yours close to that?
Yes, the LSA, its quite a rare airplane.
there are few things that bother me about the his design however.
The tail is right in the prop wash axe that make it more prone to slip stream effect, i want my airplane to be a comfy cruiser easy to fly so i raised the tail higher like for the CH701.
i also wanted a small luggage area and more leg room.
the elevator control is push pull rod instead of cable.
finally, the flaps are the length of the wing (flaperon) so i wont have to run the controle cables on the struts or inside the wing.

there are other few differences, like i said its inspired by it, its not a copy and i don't have Milholland's the plans.
the goal is to build a very simple and cheap airplane that can also be used to cruise long distences
 
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Malcolm C

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May 18, 2020
Messages
41
Hi Merlin and welcome, are you planning on having folding wings,? very desirable feature.......
 

Merlin

Active Member
Joined
Nov 17, 2020
Messages
43
Hi Merlin and welcome, are you planning on having folding wings,? very desirable feature.......
No, but they can be removed relatively easily with proper tools, every part of the airplane should be easily accesble for maintenence
 

akwrencher

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Joined
Oct 16, 2012
Messages
1,314
Location
Gustavus, AK
I'll see if I can get some pics for you.Screenshot_20201126-131252_Drive.jpg

You can see the cross section.
I beam style. Also see MiniMax construction, they use similar but not sloted, looks more like a c channel. Ply glued to the sides of the caps instead of in the middle. Lots of variations. I'm no expert and have not built anything yet.
 
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akwrencher

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Oct 16, 2012
Messages
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Location
Gustavus, AK
Also, check out Dennis Tyson's "1100R MiniMax Vlog" on YouTube for some good wood construction info if you go with a wood wing.
 

Doran Jaffas

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Joined
Jun 25, 2019
Messages
315
My name is Merlin, i'm 32 and currently designing my first airplane, it is inspired by Milholland's Leagle Eagle but in two seat version.
the idea is to build an airplane for under $3k that won't take me years to finish, it should take around 6 months to build.

I have already completed the welded chassis in SolidWorks and made sure there were no weak points, however i'm having problems chosing the proper wing spars.
Simulation of wood or carbon fiber on Solidworks is neither easy nor particularly accurate considering the properties of the material. Aluminium strenght to weight ratio doesn't seem ideal.

I'm a bit stuck at the time and i would appreciate some advices.

thank you :)
I'd very much like to track your progress. I'm looking for a bird like yours to add as a stable mate for my Tailwind W8.
 

David Lewis

Active Member
Joined
Oct 4, 2018
Messages
31
Location
Longwood FL
Please verify with experts but my understanding is wood wing airplanes should be stored in a hangar.

Also, do you have a preliminary 3-view sketch?
 

Lendo

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Joined
Feb 6, 2013
Messages
602
Location
Brisbane
Merlin, Purchase Jim Marske's manual on Carbon Rod Spars. Lightest and easiest to make and he does all the Maths for you in examples and will sell you the Rods as well. Note not all Carbon rods are the same, buy from reputable Aviation suppliers. The US Manufacturer does not sell direct, but Jim is an agent for them and is always available to give advice. There are in his manual also examples on how to Join folding wings etc.
His rod count for caps are correct, but as he doesn't allow for Buckling in the Web, he says he has never experienced buckling in his designs (Gliders) - perhaps double his wraps, however this is just a WAG. I haven't yet worked out how to correctly apply the Cantilever Buckling Formula to his formulas and neither does he by the sound of it.
George
 

Merlin

Active Member
Joined
Nov 17, 2020
Messages
43
Please verify with experts but my understanding is wood wing airplanes should be stored in a hangar.

Also, do you have a preliminary 3-view sketch?
I went strait to Solidworks and used toplogy optimization for ideal weld placement.
 

Merlin

Active Member
Joined
Nov 17, 2020
Messages
43
Merlin, Purchase Jim Marske's manual on Carbon Rod Spars. Lightest and easiest to make and he does all the Maths for you in examples and will sell you the Rods as well. Note not all Carbon rods are the same, buy from reputable Aviation suppliers. The US Manufacturer does not sell direct, but Jim is an agent for them and is always available to give advice. There are in his manual also examples on how to Join folding wings etc.
His rod count for caps are correct, but as he doesn't allow for Buckling in the Web, he says he has never experienced buckling in his designs (Gliders) - perhaps double his wraps, however this is just a WAG. I haven't yet worked out how to correctly apply the Cantilever Buckling Formula to his formulas and neither does he by the sound of it.
George
Will check, thank you.
carbon reenforced wood spar seems like a neat compromize.
 
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