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Hotwire airfoil vs foamboard airfoil ( old technique style and master style )

#1
Hotwire airfoil , getting very close to the desired airfoil . The old flight test technique ( on ft storch, mig 3 , etc ), effective but not a precise airfoil. And the new master series airfoil

how theese airfoil building techniques compare with eachother ?
 

Merv

Well-known member
#2
From my experience the flat plate wing is the very inefficient wing. Adding a KF air foil to a flat plate wing is a great improvement. Going to a faceted FT wing is another step up from the KF. The next step up is a folded Armin wing, which is a slight improvement from the facets of a FT wing. An improvement for both the FT wing and the Armin wing is the tapered aft portion of the wing like Andrew Newton depron wing. I have incorporated Newton's taper & Ed's kissing tape into the FT wing. The result my Versa will glide forever. With catching a few thermals, I've had flights over 30 minutes.


 
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Pieliker96

Well-known member
#3
Standard old-fashioned spar & ribs & skin construction can be done with foamboard as well as long as the planform doesn't have complex taper and there isn't any wing twist.

20190802_115108.jpg 20190803_141913.jpg
 

wilmracer

I build things that fly (sometimes)
Mentor
#4
All have their advantages and disadvantages. IMHO It is tough to beat hotwire airfoils for the combination of ease and accuracy, and if you're willing to use some composites along with the foam cores you can get incredibly slick, precise wings relatively quickly. It isn't as easy as the traditional FT fold over, and is still probably harder than the master series (haven't built one), but the results are there.

I'd be asking what type of aircraft, what type of flying, are you trying to squeeze every bit of efficiency out of the airframe, and how much effort are you willing to put in.
 

bracesport

Well-known member
#5
My DLG wings use two sheets of foam (de-papered) either with sanded or hot wire cut internal surfaces that are then laminated together to make a foil - works well! :D
 
#6
I'd be asking what type of aircraft, what type of flying, are you trying to squeeze every bit of efficiency out of the airframe, and how much effort are you willing to put in.
I plan on building a 100 km/h jet attacker ( EDF ) , 1m length. Main focus is on the design and analysis of the plane , so I want an airfoil that behaves close to the airfoil of the plans ( NACA 2414 , or something simmilar )
 

Piotrsko

Well-known member
#7
You can easily get to a 64a012 profile in dtfb which is real close to the 2414 but 2% less thickness and some less undercamber so its flatbottom. Notice that it is a 40% laminar with a hairy COP. You will need to make tapered balsa trailing edges. Anything more exotic and thicker needs the interior paper removed and rib profiles added then sand the leading and trailing edges to taper them properly.

However this is model scale and in my experiences, shoe profiles work just as good
 

wilmracer

I build things that fly (sometimes)
Mentor
#8
I plan on building a 100 km/h jet attacker ( EDF ) , 1m length. Main focus is on the design and analysis of the plane , so I want an airfoil that behaves close to the airfoil of the plans ( NACA 2414 , or something simmilar )
So I guess the next question is what is the purpose of the analysis of the airframe. There is no reason you couldn't easily hotwire, sheet, and glass wings with that exact profile (use this for template http://airfoiltools.com/airfoil/details?airfoil=n2414-il ), but at this scale the analysis likely wouldn't translate to a larger airframe.

TBH, just pick the method you're most comfortable with unless you want to practice with new techniques.
 
#10
So I guess the next question is what is the purpose of the analysis of the airframe. There is no reason you couldn't easily hotwire, sheet, and glass wings with that exact profile (use this for template http://airfoiltools.com/airfoil/details?airfoil=n2414-il ), but at this scale the analysis likely wouldn't translate to a larger airframe.

TBH, just pick the method you're most comfortable with unless you want to practice with new techniques.
I know , diferent sizes will behave differently. The purpose of the analysis is just to challenge myself to get better at cfd , get some numbers , and to try and go through the design phase more realistically.
 

wilmracer

I build things that fly (sometimes)
Mentor
#11
I know , diferent sizes will behave differently. The purpose of the analysis is just to challenge myself to get better at cfd , get some numbers , and to try and go through the design phase more realistically.
Cool! My vote would be hotwire for accuracy, resulting in more consistent and repeatable performance. And of course you get to work on a new skill (assuming you haven't done it before). Have fun!