A very interesting and thought provoking explanation of why the conventional wisdom of elliptical lift distribution needs rethinking. Interesting for lovers of fixed-wing but also might be applicable for propellers and rotors...?
Watched this twice now amazing, thanks for sharing something to consider over the weekend. I know I like wings but now I like them more.
Food for thought alright. Plenty of the crashtest hobby combat wings do not have vertical fins.
What I would like is someway to relatively easily calculate the twist/sweepback/airfoil combination. I guess they are using low or positive pitching moment airfoils.
Do I understand it correctly you have negative AoA of the tips to reduce the induced tip vortex drag by reversing the lift; and it also solves the adverse yaw problem ???
Can we apply the same principle to improve the induce drag of the law aspect ratio wings???
Ha, finally some else understands that elliptical lift distribution does not work as well for a loaded aircraft. I used a bell curve lift distribution when designing the techpod, although not quite as radically as done on the Prandlt wing in this example.
Brilliant! Thanks for sharing
You seem to be conflating a whole bunch of disparate concepts there Justin. Give us a call back when you've got your thoughts together as clearly as Mr Bowers obviously has.
Yes, it's true that Dr Prandtl wrote his paper in the 30's and some of us have seen it before. There is a lot of received wisdom floating about and Mr Bower's presentation did a sterling job of blowing some of it away.
I don't get your (now deleted) point about flutter and pitch stability w.r.t. the Prandtl lift distribution proposal. Flutter is an aeroelastic phenomenon related more to wing torsional stiffness and aerofoil pitching moment and pitch stability is driven mostly by CoG relative to the NP. I don't see how wing lift distribution affects it in a generic way for all cases although it might be influential in some specific (esoteric?) instance. Care to explain?
Interesting, though I dont see this as that new? It has been covered in detail in various books on aerodynamics from 70's 80's AFAIK
I built a wing using a bell shaped lift distribution and found it performs well.
Tensor V2 article on DiyDronesBUT ....There is one important point that was glossed over though made by the questioners at the end.The efficiency of the bell shape lift distribution is optimised very much for one airspeed.At high airspeeds the bell shaped wings start physically bending down due to the load on the tips and cause high drag.The drag increases very quickly and has to be counteracted by lift at the root, so you run into a brick wall if you try to go fast..With an elliptical lift distribution, though the peak efficiency is less, you have a much wider flight envelopeSo the bell shaped lift distribution is potentially good for airliners or endurance, however, if you need to cover a wide range of airspeeds, then an elliptical lift distribution is better.The info regarding proverse yaw is useful though especially so for stealth aircraft I guess
But the narrow flight envelope is why you dont see it used on general purpose aircraft
Join DIY Drones
Welcome toDIY Drones
Sign Upor Sign In
Or sign in with:
© 2020 Created by Chris Anderson.
Report an Issue |
Terms of Service
Please check your browser settings or contact your system administrator.