Help! select an airfoil with high lift for low speeds

[Look74482]

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I am a student and I am trying to make an Rc airplane about a competition in my country. Well, I am thinking for a fixed wing rc plane and I am doing different aerodynamic analysis(XFLR5) in order to select an airfoil with high lift for low speeds(cruise speed 10 m/s) (low Reynolds Number).
So, I would like your opinion about, does an airfoil play an important role for such a small Uav( approx. Total mass 1kg, wingspan 1.5m, chord 0.25m) and if yes do you suggest any airfoil that will maximise my plane performance.

Thank you!

 

[quorneng]

Look74482
The aerofoil section does play a part but a very low Reynolds numbers it is not the most important factor but wing loading usually is. Wing loading is area/weight the planes weight also has a big effect on the minimum fight speed.
To get the full benefit of any wing section it has to accurately maintained over the entire wing. This in practise means that for a given size wing you have to make a judgment between the accuracy of the wing section and the structural weight needed to create it. At very low Reynolds numbers the bias of this judgment moves towards achieving the best structural efficiency. This in turn means selecting the best component material(s) for the load they have to carry. Understanding the load each component of an airframe has to carry is complex to say the least.
One further point. The power required to fly is directly proportional to the plane's mass. If the plane is electric then the battery weight and expected flight duration is significant too. You mentioned a plane mass of 1kg. Is this a competition requirement or an estimate on your part?
1kg for a plane with a 1.5m x 0.25 chord wing is not a light weight but it does depend on what the plane has to do.

As you can see it is not as simple a just selecting the aerofoil but includes a whole range of other parameters for which there are no simple mathematical formulae to give you the ideal solution. In the RC model plane world much is down to experience derived from trial and error.

If you posted the rules & objectives of your competition it would help the expertise on this forum to suggest the most likely route to achieve success.

 

[Look74482]

Look74482
The aerofoil section does play a part but a very low Reynolds numbers it is not the most important factor but wing loading usually is. Wing loading is area/weight the planes weight also has a big effect on the minimum fight speed.
To get the full benefit of any wing section it has to accurately maintained over the entire wing. This in practise means that for a given size wing you have to make a judgment between the accuracy of the wing section and the structural weight needed to create it. At very low Reynolds numbers the bias of this judgment moves towards achieving the best structural efficiency. This in turn means selecting the best component material(s) for the load they have to carry. Understanding the load each component of an airframe has to carry is complex to say the least.
One further point. The power required to fly is directly proportional to the plane's mass. If the plane is electric then the battery weight and expected flight duration is significant too. You mentioned a plane mass of 1kg. Is this a competition requirement or an estimate on your part?
1kg for a plane with a 1.5m x 0.25 chord wing is not a light weight but it does depend on what the plane has to do.

As you can see it is not as simple a just selecting the aerofoil but includes a whole range of other parameters for which there are no simple mathematical formulae to give you the ideal solution. In the RC model plane world much is down to experience derived from trial and error.

If you posted the rules & objectives of your competition it would help the expertise on this forum to suggest the most likely route to achieve success.

Hello sir and thank you for your answer,
well the rules are the total mass less than 1 kg, max altitute 30m, the design of the rc plane is flexible, the values that I gave for chord and plane is approximate an astimation due XFLR5 analysis for a specific airfoils. ex. MH113 and s1223.. but also I checked other airfoils with the same charecteristics in 3D analysis but I was wondering if there is any airfoil which can maximize the performance of my RC without considering battery,propeller etc

 

[Merv]

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... does an airfoil play an important role for such a small Uav... if yes do you suggest any airfoil that will maximise my plane performance...

Yes, airfoil is important. But not as important as the pilot and build quality. In other words, a well build tiny trainer in the hands of a skilled pilot can out preform the best airfoil that is poorly built & flown by a novice. Your choice of airfoil may change the performance by 10-20%, your piloting skill's and build quality can easily exceed that.

Regarding airfoils, the Clark Y is simple and easy & has good performance. The more advanced NACA 2412, 4094 & 4412, are popular in sail planes.
Here are some other resources that may help.

Help! - Airfoil for a glider

Hi, im building a 2,6 meter scale glider pretty heavy. The wings will be cut out off styrofoam and covered with fiberglass. Its my first time cutting wing, and trying to fly a rc plane. It should be a pretty thick airfoil because i have to fit a 10 mm carbon rod inside. and the cord is about 15...

forum.flitetest.com

Glider airfoil

Hi guys, I made need your help on this one. We are running for a competition and need to build our own glider. What airfoil type would you recommend for a max. wingspan of 1m and max. weight of 200g? The glider will be hand launched from a height of 2.5m to an open field and the longest...

forum.flitetest.com

UIUC Airfoil Data Site

 

[quorneng]

Hi
You need to consider what you mean by "performance".
Is there a minimum flying speed, duration or a specific motor that must be used?
Without this sort of limitation the design of the plane is very open. There are commercially available designs or even ready to fly planes that could meet the limited criteria you have set out.
In practise almost any aerofoil, even a flat plate, can achieve the sort of low flying speed you mention if the wing loading is low enough.

As an example I developed the design of this plane over quite a period. It is 95% constructed out of thin sheet foam. Its wing is close to your dimensions.

It uses a Clark Y wing section as with a flat bottom it is easy to construct and has 'gentle' flight characteristics but the most important factor is its weight at 436g. Note close 40% of that figure is due to the battery!
It can fly at quite a bit less than 10m/s and can do so under power non stop for nearly 4 hours.
You can see what I am getting at.
Unless you are planning to glide for the maximum possible distance (L/D ratio) the wing section is not as critical as the planes size to mass ratio or put another way the airframe structural efficiency.
The parameters of the competition or those that you set yourself will have a big influence on the "best" design.