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Extreme Squirreltail 300 Coming at you

Wildthing

Well-known member
#41
Dude as Josh said in a flight test video one time, on a Model our scale it's just not that critical but when you get it just right there's a difference it's like engine with a bad spark plug wire or a bad sensor it still runs pretty good but when everything is right it's golden! Seriously check out the two airfoils I suggested and read up on airfoil data for RC models if you want I have a paper I can email to you.
My airfoil is very close to the E474 one.
 

L Edge

Well-known member
#45
Point in question. When hovering(worst case having no forward airflow), your ailerons need good prop generated airflow across it. If there is not enough airflow, your plane will rotate when hovering and won't stop. Allow enough blank width for construction, but if you start 3-5" out from fuse, it might become a dog, most likely.

How far is your's? You should also decide what dia prop you are using. Add's to the equation when you don't know fuse width. Isn't this fun!!!
 

SquirrelTail

Well-known member
#46
Point in question. When hovering(worst case having no forward airflow), your ailerons need good prop generated airflow across it. If there is not enough airflow, your plane will rotate when hovering and won't stop. Allow enough blank width for construction, but if you start 3-5" out from fuse, it might become a dog, most likely.

How far is your's? You should also decide what dia prop you are using. Add's to the equation when you don't know fuse width. Isn't this fun!!!
These are words of wisdom!!! Lol. I have big planes that have the ailerons that go full length, and hovering is 100 times easier to do than with my 50cces with a 3" trailing edge piece at the fuse
 

L Edge

Well-known member
#47
These are words of wisdom!!! Lol. I have big planes that have the ailerons that go full length, and hovering is 100 times easier to do than with my 50cces with a 3" trailing edge piece at the fuse
Prop dia(+ other things) is also a big influence on size and how you shape of your rudder that must handle hovering as well as forward flight. If it causes too much interaction in the other axis, it doesn't meet standards. Weight is also a factor in performing.
I have a 50 cc fiber composite bird that weighs 12lbs and 2 oz. that is usually 3-5 lbs lighter than competator's. It even has kevlar hinges making it a sharp bird to fly. Where you put it, it stays there, just like a pattern plane.
 

Wildthing

Well-known member
#48
I appreciate all the info , I am trying to keep this as scale as possible to a proven plane so I am hoping it will be somewhat decent. Weight I have no system to even gauge what it will be until I am done. The blank width I have here is about 40mm, wing span will be aprox 1200.
 

BATTLEAXE

Well-known member
#50

AkimboGlueGuns

Biplane Guy
Mentor
#55
On the topic of airfoils, especially symmetrical ones...

Turbulence isn't the term you're looking for, its drag. The thicker the airfoil you select, the more induced drag you'll have to deal with. Great for low speeds, but performance suffers at higher speeds. In general terms, thinner airfoils are more suited to high energy maneuvers as they're generally easier to stall (important for maneuvers like snaps, spins, blenders, pop tops, etc...) and thicker ones handle low speed maneuvers better as they have a larger boundary layer (this is the area of attached airflow which will depart the wing in a stall) and improve control authority at high angles of attack. The only "turbulence" you're really going to be worried about on a model that can be designed out is wake vortexes, which are a byproduct of lift. Wing fences can help with this, BUT on a 3D plane you're better off going with side force generators, which help the aircraft track straighter, gives it more authority in knife edge, and helps to reduce wake vortexes. The vortexes increase parasitic drag, which will become more apparent as speed increases.
 
#56
Look for tips in the 3D build FT did. Lots of great techniques. And reasons why they are done. Wing fences are great but not a cure all like mentioned above. And you said your Airfoil design was close to the eppler, close doesn't count in Airfoils... Sorry. you can download almost any Airfoil in dwg format and extrude it to your wing shape. Check out https://www.airfoiltools.com and this site https://www.mh-aerotools.de/airfoils/index.htm ... Tons of great info especially on RC aircraft and how our airfoils are different as well as recommendation. I am using the sd8052 for a project that I'm drawing and specing out. Good luck and do some research... It's out there.there are some great papers and wind tunnel testing results on Airfoils just for RC planes.
 
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Wildthing

Well-known member
#58
Look for tips in the 3D build FT did. Lots of great techniques. And reasons why they are done. Wing fences are great but not a cure all like mentioned above. And you said your Airfoil design was close to the eppler, close doesn't count in Airfoils... Sorry. you can download almost any Airfoil in dwg format and extrude it to your wing shape. Check out https://www.airfoiltools.com and this site https://www.mh-aerotools.de/airfoils/index.htm ... Tons of great info especially on RC aircraft and how our airfoils are different as well as recommendation. I am using the sd8052 for a project that I'm drawing and specing out. Good luck and do some research... It's out there.there are some great papers and wind tunnel testing results on Airfoils just for RC planes.
I need to see some of these perfect airfoils made out of FB :unsure::unsure::unsure:
 

BATTLEAXE

Well-known member
#59
I need to see some of these perfect airfoils made out of FB :unsure::unsure::unsure:
The airfoils that FT and EA have created are good range to play with. There can be variations of them but really so many people have used them and they are prove to work. If anyone can take a flat sheet and build a Nutball and get that to fly it just proves that the airfoil design isn't that critical. If you have a trust to weight ration of 0.2/1 then I could see it, but then that sucks all the fun out of it
 

Wildthing

Well-known member
#60
The airfoils that FT and EA have created are good range to play with. There can be variations of them but really so many people have used them and they are prove to work. If anyone can take a flat sheet and build a Nutball and get that to fly it just proves that the airfoil design isn't that critical. If you have a trust to weight ration of 0.2/1 then I could see it, but then that sucks all the fun out of it
Well those pictures above, that is my airfoil and I am sticking with it. :D :D

I have spent most of the day getting proper meshes so between Cura, Rhino and Tinker Cad I think I have finally won. Simple stupid pieces and Cura when slicing a model it would actually detach some parts . I had a test piece the end lifted off the board so lets add a adhesion brim to it , well it put 4 spots underneath the model actually lifting it off the bed. For some reason it also wanted to put supports in a straight up and down tube and then cap the top. I could go on and on, days like this I really hate technoligy .