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Sep 03, 2018, 05:51 PM
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RC fixed wings design


Hello everyone,
I am designing a foam-balsa-CF mixed plane. Could someone comment on my plan?
Plan:
  • Power data:
    Thrust: 870g, Mass: 1kg MAX, Wing Load: 35g/dm^2
  • Wing:
    Wing Span: 1200mm; Chord Length: 240mm; Airfoil: Clark Y11.1%; Aileron Size: 450mmX48mm; Wing on Top; Dihedral angle: up 3 degrees; CoM: 65mm after the front of the wing; Considering adding slats
  • Fuselage:
    Total Length: 840mm; Head Length: 180mm; Width: 100mm; Height(Highest): 100mm
  • Stabilizer:
    Horizontal: Size: 168mmX392mm; Elevator Size: 34mmX392mm
    Vertical: Size: (170mm+200mm)X155mm; Rudder Size: 47mmX155mm
  • Structure Build:
    Using 3mm balsa wood as frames, 3mm thick EPE foam as cover, CFs as the structural strengthen, Glass Fiber Epoxy as the strengthen of the surface.
    Using magnets, screws and rubber band as the method of fix the wing.
    Using clear foam glue (HobbyKing) and CA glue to bond materials.
Welcome to comment on my design.
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Sep 03, 2018, 06:30 PM
yank and bank!!
Actual specs in a design.... well done!!!!


You just joined..... I don't know if you have experience flying rc planes, but starting out with a relatively underpowered scratch built plane as your first plane is a bad idea.... ask me how I know.
Sep 03, 2018, 07:00 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
There's an RC Groups forum for builders :
https://www.rcgroups.com/the-builders-workshop-131/

Will you be using this plane to teach yourself first time RC flying ( unassisted by an experienced RC flyer ) ?
Sep 04, 2018, 04:14 AM
An itch?. Scratch build.
eflightray's Avatar
Quote:
Using magnets, screws and rubber band as the method of fix the wing.
.


The third picture has me puzzled ? it looks rather like a 'V' tail.

.
Sep 04, 2018, 04:57 AM
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Thread OP
Quote:
Originally Posted by failboat
Actual specs in a design.... well done!!!!


You just joined..... I don't know if you have experience flying rc planes, but starting out with a relatively underpowered scratch built plane as your first plane is a bad idea.... ask me how I know.
Thanks for your reply. I have only flown planes in RC simulator several years ago.
As for underweight... I found a data from experience that: the thrust:weight ratio of the normal plane is from 0.8 to 1 (3D is over 1 and glider is about 0.5). There will be an upward force carried by wings. So why mine is a bad idea?
(Actually, I ordered the whole power system for a light plane., but I suddenly found that the plane on the original plan is a 3D trainer foamie plane... Therefore, I have to design a basic trainer to fit the power system. Because I am going to use EPE foam -- it is lightweight, high tear-proof, waterproof, high-grain, good force absorption etc, but it is very soft, I have to strengthen it, which means weight.)

Quote:
Originally Posted by balsa or carbon
There's an RC Groups forum for builders :
https://www.rcgroups.com/the-builders-workshop-131/

Will you be using this plane to teach yourself first time RC flying ( unassisted by an experienced RC flyer ) ?

Thanks for your link. I just don't know what is the kind of discussion of my plan so I start a thread here.
And... yes, this will be my first RC plane in reality to fly, but I will find a club in my area to fly with.

Quote:
Originally Posted by eflightray
.


The third picture has me puzzled ? it looks rather like a 'V' tail.

.

This idea comes from a patent I found. It is to use magnets mainly to fix, the screw to find the place. I add rubber band to make it not going to fall apart.
You can search "CN 202538350 U" on google patents for details.
Last edited by AndySmiot; Sep 04, 2018 at 12:40 PM. Reason: To reply more people and further description
Sep 04, 2018, 09:24 AM
Registered User
Thread OP
Quote:
Originally Posted by balsa or carbon
There's an RC Groups forum for builders :
https://www.rcgroups.com/the-builders-workshop-131/

Will you be using this plane to teach yourself first time RC flying ( unassisted by an experienced RC flyer ) ?
I have seen your post here: https://www.rcgroups.com/forums/show...-CRASHING%21#2
This is very similar to my original plan... Mainly using EPE foam; and massive of paulownia, balsa and CF as the strengthening.
Do you think it is good to go for beginners?
Sep 04, 2018, 01:15 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by AndySmiot
Thanks for your link. I just don't know what is the kind of discussion of my plan so I start a thread here.
And... yes, this will be my first RC plane in reality to fly, but I will find a club in my area to fly with.
For flying your plane : if you will have the assistance of an experienced RC flyer at a club .... you will have a good chance for success .

For building a plane : if this is your first time building a plane .... I recommend starting with a simple , proven design . Like almost everything in life , it's best to first learn to crawl , then learn to walk , then learn to run .

Please let us know how this turns out !
Sep 04, 2018, 01:31 PM
An itch?. Scratch build.
eflightray's Avatar
The -- Foamies (Scratchbuilt) forum -- has some 'Sticky' threads at the top listing loads of existing plans.

Also the 'experienced RC flyer at a club' should, I hope, have enough knowledge to explain what is right or wrong with your design.

As 'b or c' posted, starting with a proven design is the best way to gain experience prior to designing your own.

.
Sep 04, 2018, 06:57 PM
Registered User
Thread OP
Quote:
Originally Posted by balsa or carbon
For flying your plane : if you will have the assistance of an experienced RC flyer at a club .... you will have a good chance for success .

For building a plane : if this is your first time building a plane .... I recommend starting with a simple , proven design . Like almost everything in life , it's best to first learn to crawl , then learn to walk , then learn to run .

Please let us know how this turns out !
Actually, I have got tons of great plans... Most of them are for balsa... If I have got the ability and assistance, I will really like to do one or two of the plans -- those are for two different levels of beginners (Basic and 3D). You are right, I tried to run before learning to crawl. There are lots of great proven plans that I can do. I am thinking to convert a plan with balsa to foam, or to adjust a little bit to the plans in this forum to fit my power system.

Quote:
Originally Posted by eflightray
The -- Foamies (Scratchbuilt) forum -- has some 'Sticky' threads at the top listing loads of existing plans.

Also the 'experienced RC flyer at a club' should, I hope, have enough knowledge to explain what is right or wrong with your design.

As 'b or c' posted, starting with a proven design is the best way to gain experience prior to designing your own.

.
Thanks for your suggestion, it really helps. I have found a plan in consideration. (Oshkosh) Or to adjust one of my plans.
Sep 04, 2018, 09:17 PM
Registered User
E-Challenged's Avatar
For a first own-design build, I'd recommend a basic high wing monoplane similar to a Piper Cub or Cessna with standard two wheel landing gear and a steerable tail wheel. You will need to provide for a sturdy motor mount, landing gear mounting, battery compartment and servo mountings in fuselage and wing as well as pushrod linkage from servos to control surfaces all with concern for balance of the model without need for adding heavy nose ballast. There are a number of other details to be concerned with. That's why it's best to buy a simple high wing foam trainer, learn to fly it safely with an instructor and then try to design and fly your own design. A high wing trainer with two wheel landing gear and steerable tail wheel is best way to
eventually graduate to warbird and high performance models with that type of landing gear.
Sep 05, 2018, 12:10 PM
Registered User
Thread OP
Quote:
Originally Posted by E-Challenged
For a first own-design build, I'd recommend a basic high wing monoplane similar to a Piper Cub or Cessna with standard two wheel landing gear and a steerable tail wheel. You will need to provide for a sturdy motor mount, landing gear mounting, battery compartment and servo mountings in fuselage and wing as well as pushrod linkage from servos to control surfaces all with concern for balance of the model without need for adding heavy nose ballast. There are a number of other details to be concerned with. That's why it's best to buy a simple high wing foam trainer, learn to fly it safely with an instructor and then try to design and fly your own design. A high wing trainer with two wheel landing gear and steerable tail wheel is best way to
eventually graduate to warbird and high performance models with that type of landing gear.

Thanks for your suggestion, I will build a plane that can fit my power system (Thrust: 870g). I have never made a foam plane, so I have no idea how much the weight of the plane is as the result.
Your other suggestions are helpful. I am gonna to take those in consideration for my build.

Quote:
Originally Posted by JureZ
AndySmiot
see attached a few reference files for more or less standard designs

Thanks, really appreciated. I will take deep in look at the Notes.
Roughly read it. Found there is no description on the thrust, mass and wing load; only many useful aerodynamic rules for aircraft design. Despite this, this guides my design to a more theoretic way rather than experience.
I found that normally the wing load is around 36g/dm^2 (For scale RC, it seems to be much greater, and that's why they will be a bit easier to stall; and for gliders, it seems to be much less).
The data in the first pdf is for convenience(from experience), sometimes it doesn't apply. The data you provided between engine displacement and wing area is not relevant to electric I am afraid, or some conversion equation for that.
Now I am carefully reading the second pdf, think it will help.
Sep 05, 2018, 03:42 PM
Registered User
Thread OP
Quote:
Originally Posted by JureZ
AndySmiot
see attached a few reference files for more or less standard designs
The Lab note is enough for the beginning design process, still lack something like:
1. Lift and Drag force for power calculation and structure strength approximation (further design).
2. appropriate AR, ARh, ARv ratio.
3. a proper bank angle, etc.
Also, the shape and strength of the fuselage are the points.
Anyway, thanks for your note, really helps.
Sep 05, 2018, 07:49 PM
Sokol
JureZ's Avatar
Quote:
Originally Posted by AndySmiot
Anyway, thanks for your note, really helps.

you are most welcome !
Sep 06, 2018, 02:55 AM
Sokol
JureZ's Avatar

Charts for the scratch builder.


see also the attachments here :
Charts for the scratch builder.
https://www.rcgroups.com/forums/show...r#post17179115

book
https://www.scribd.com/doc/242566034...rodynamics-pdf
Last edited by JureZ; Sep 06, 2018 at 03:05 AM.


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