I figure long wings are a must, but how "short" wings could be in theory to get 70+ L/D ?
AR plays a pivotal role too I assume ?
Wingloading and interference drag are inportant too ?
Air speed has gotta be the best too:
What is the definition of "best L/D"?
You are right - L/D optimalization depends on all details like AR, wingloading, drag reduction etc....
I agree with argument that L/D is not the most important parameter.
Of course is nice to have super high L/D, but you have to consider also typical use.
Concordia, ETA... all this super high end projects are pushing limits forward. It is "pure competition gliding".
However now we are in category 200K EUR plus....
What do you really need?
Unless you are competition pilot you need to have fun.
Fun for me =
... no stress with Takeoff. It should be self launch.
... no stress with assembling. Ideally light and simple enough to be assembled by one person.
... easy to fly etc.
In simple words - I need to be independent because when I want to go to the air I should go to airport and fly.
Performance is also important, but we are in category of "reasonable performance".
L/D 70:1 means high end glider - like a flying "rolls-royce".
If you have very low sink ratio at low speed, you can use weak or narrow thermals and quickly get altitude.
But light small glider cannot reach high L/D.... and here is (in my opnion) space for electric "L/D sponsoring".
Argument from glider pilot wil lbe that this is not "pure gliding" anymore....
But it doesn´t mean that this type of flying is not "pure fun"
My "dream goal"?
Take off using electric motor. Use propulsion to first thermal, switch off motor and use lift up to cloud base.
Leave could base and let solar panels to feed electric motor and increase L/D with few kW of solar power.
Maybe can solar power already help during climbing - why not?
My "ultimate dream goal" will be achieved when we "harvest" enough solar energy for horizontal flight....
Actual goal?
Make prototype with electric motor (at the beginning without solar panels) and measure real data.
For example....
- how much energy I need for horizontal flight
- how far can I get with 5-6 kWh battery after 1x takeoff
- how fast can I recharge from "standard" electric plug
- what is temperature of solar panels on direct sun (installed on wing samples)
- how much solar energy I can really get with actually available solar panels
- etc...
....so many usefull informations I cannot get without real tests...
www.secretprojects.co.uk
en.wikipedia.org
www.homebuiltairplanes.com
www.youtube.com
