As of any RC model weight is key but particularly with these kinda of planes. You see these airliners in the availiable scale configuration are very susceptible to weight. Well as mentioned anywhere from 1500mm-2000mm wingspan. Someone asked for size weight I had in mind. Yet I was hoping that the gains In lift and slower speed meaning the motors are working at lower RPM's to remain in level flight and the ability to glide to some extent would out way the initial increase In drag. I knew If I were to approach those changes mentioned all of them would incur some increase In drag sadly. My model is a 1500mm wingspan but should I build my own from scratch It will be more towards 1800-2000m Hi again guys firstly thanks for the great info! (It is possible to work out the stall speed of a model in the design stage, if you are interested.) Changing incidences will change the trim speed but not the stall speed. But the angle of attack the model is capable of and hence the stall speed, is set by the max CL and aspect ratio. 'Angle of attack' is actually the angle at which the wing is presented to the airflow, not the wing incidence on the model. You cant have everything sadly! Unless you go for functional flaps, which is what allows full sized airliners to cruise efficiently and yet slow down for landing. The problem with a high lift under cambered airfoil is you will limit the top speed. These airfoils are also more efficient in terms of duration on a given amount of power. Also a simple curved plate is quite effective in small models. Have a look at free flight duration airfoils. So your modification is likely to add drag and not help the speed unless it is a substantially sized model.Īs mentioned an undercambered airfoil generally gives a better max CL as it has the camber without the thickness. In general terms increasing camber will increase the max CL of an airfoil but small models tun into problems with 'Reynolds numbers' - air tends to behave differently around small, slow flying wings.Īt low Reynolds numbers (think indoor models) thick airfoils are a no no - the thickness actually reduces the max CL. Increase the maximum Lift Coefficient that the wing is capable of (improve the airfoil.) This means a wing of the same area can 'work harder' as it were. Reduce the wing loading (increase area for same weight)Ģ. So here's my plan from my tiny mind on paper for now.ĭoes anyone see any sense in this.Or more so see any reason why this wouldn't work or at least help my cause?ġ. I understand why this is great for a real airliner but again for RC models not so much were not reaching high speeds here or trying to cart 300 passengers to there destination as fast and financially possible. ADD MORE WING!!ģ Reducing the swept back wing somewhat. So some things I wish to change to create my own model.Ģ possibly increse wing surface area by way of wing extensions fixed or flaps retractable In a nut shell. So airliners not the smartest choice for RC even so I have to have one! There the planes that most warm my otherwise cold heart :P And so I am saddened to no end by the what I would call poor performance. Making any changes we discussed will no doubt have an effect some will say ruin the scale aspect but I'm not too caught up on that if I'm honest remember Happy medium So heres what is cooking up in my tiny mind. I wish to do something about such problems if only marginally. So anyone who might understand airliners will understand why they are the shape and size and specifications that they are But for RC models It don't really make for a a great Rc plane unless you like flying very fast using colossal amps and landing "At speed" after 4-5 mins because your lipo's are critically low :/ Ok so I own a EDF A380 Airliner EDF's are notoriously inefficient but Lets not get into powerplant/powertrain I wish to focus on airframe only ATM. I believe both camber and angle of attack go hand in hand and is called "coefficient of lift" In my mind Increasing the angle of attack alone would do nothing to reduce stall speed and would just keep my plane looking marginally more level in flight as It approached slow stall speed? I don't hold heaps of knowledge on airfoils and have never made a model of my own so forgive me if I am making assumptions or missing points along the way. Might increasing the angle of attack of said wing give better performance at slower speeds too. But as for camber would adding a few mm,s of camber to the total span of wing have much effect? One could also increase the wing area too right. If you were to increase airfoil camber alone would that help enough? Lets say you wanted to improve flight characteristics at slower speeds and or increase the amount of lift at any given speed. Say the said model liked to fly fast/land fast and didn't generate much lift at slower speeds. Say one had a model any model it doesn't matter.
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