Or perhaps you should ask if planes with thinner airfoils work better with electric motors than glow?

Thin airfoils will help you keep the speed up, often too much.  They'll generate more lift in the turns before they stall.  It is _possible_ that if you have a thinner airfoil and a big fan in front to keep the speed down that you could do well with electric -- but I'll wait for someone else to try this before I go build a model.

Jim,

It is not electric power that has changed the thickness of our airfoils. It is the change from having almost NO power with the felon fox engines that required thin airfoils and low drag planes to fly the pattern, to when CL got unlimited, useable power with our modern engines like PAs and other engines on pipes and very powerful 4 strokes. Electric is just a more reliable and repeatable version of the above very powerful engine systems.

This abundance of "power" is what allowed the experiments in very high lift, high drag, thick airfoils. These experiments will continue wether the plane has a beautiful, extremely powerful PA .75 on a pipe or an equally powerful Plentenberg motor up front. The fact that one has electric power has very little to do with the airfoil selection.

E power will have an impact on construction (weights in different places, low vibration, no need for fuel proof finish, etc.), and some design issues (barbell, etc.). But it will not have any impact on airfoils.

At our very low speeds (50 to 60 MPH), and low Reynolds #s, our CL planes need to worry about induced drag in our corners, and having low stall speeds. Thick wings work well in this environment, they produce a lot of lift at our low speeds and they have lower stall speeds than a thin wing at similar wing loadings. But thin winged Noblers and other classics still fly real well, in the right hands! :-)

I'm sure you will find some lively discussions on this "thickness" topic over on the design forum. ;-)

We need a take apart plane with plug in wings tat we can change and try different foil thicknesses etc. Then we can evaluate the power consumption variation and if we can fly with smaller batteries. The problem here is the thickness of the airfoil is directly proportional to the weight of the plane. Heavy plane fat airfoil light plane thin airfoil. Fat airfoil needs more power and more battery then thin airfoil needs less power and less battery. But the question here is where is the better balance found? And the test is in the way the ship performs. Maybe someone can calculate these parameters but i see to many variables. Paul has a 2.2in thick and he thinks it could go to a thinner airfoil so it may be a great place to start. My plane has 2.375 but it is thinner at the tip to have more of am elliptical lift distribution.
Good luck

Au contraire.  

I know that it's conventional wisdom that thick stunt wings have lots more drag than thin ones, but I doubt it, particularly if you take into account induced drag from the additional structural weight needed as the wing gets thinner.       

Really?

Are we talking here 18% including the flaps cord?
If that a wing with 10in root cord and a flaps 3in cord it would come up to 2.34in thickness just above what Paul is using today. And he is considering going down on this thickness.

"The problem here is the thickness of the airfoil is directly proportional to the weight of the plane. Heavy plane fat airfoil light plane thin airfoil."

Wrong !  I think I have shown that many many times over, as well as several others


Randy

A year ago I did an experiment with a thin airfoil to see how it would work out. Used a 12% airfoil on en electric to see if we could go that thin to decrease drag and lower the mah draws for pattern. The plane had a 573 sq's and was powered by an axi 2826/12. We had three experienced stunt fliers, evaluate it Performance. Power was fine. Performance suffered. We saw stalls in the corners, both the squares and the triangles. We worked at different air speeds but were not able to solve the issue. Our conclusion was that 12% airfoil while creating less drag did not produce corner performance adequate to the modern stunt pattern's requirements. I just offer this as a data point of what we felt was as thin an airfoil as any of us wanted to try. Your mileage may vary. 

bob branch

It is not the best idea to separate only the drag from equation. Yes, we can use thinner airfoil and still have enough lift for carrying the weight. But if you do so, for example half of the thickness which will do only half of the maximal lift coefficient, we will need twice the area. It will fly well, but what will happen in wind and turbulence? And why you think it will make lower drag? If the drag coefficient will be also half, we will get the same drag because of large area.

This is exactly why we use flaps. It helps to minimize area and thus flyability in wind and turbulence.

Another thing is drag in level and drag in maneuvers. Yes, we can use high wing load with thin wing and will have probably lower drag, but the drag could be higher than drag of thick wing in maneuvers. It will change the speed, and the only solution for that is stronger power train. Exactly what we did not want with that thinner wing.

I use my 18% thick airfoil which has minimized drag at high lift with flap at 30%, while airfoil drag at 0 lift and 0 flaps is relatively high. It gives good chance also with relatively small prop 12x6, also in wind and turbulence and with relatively high wing load. (6 cells of A123)

"Thin airfoils will help you keep the speed up, often too much.  They'll generate more lift in the turns before they stall. "

Hi Tim

It doesn't seem to work that way on my ships , keeping speed up is not any problem and thinner airfoils I have used , and seen,stall in corners before the ones I use that are thicker. Mind you my SV airfoils are not nearly as thick as others but are thicker than typical Nobler type thin foils

I got that second sentence backwards!!  Thick airfoils (to a point) will generate more lift before they stall.

D'oh.  The typing gods were not being kind to me that day.

Igor when you say 18% is it without flap cord or it includes the flap cord?

Yes, it is derived from NACA0018 (LE) with reworked hingeline.

yes yes 

yes, including