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Discussion in 'Hangar Flying' started by Speedboat100, Aug 20, 2019.
=KASPERwings have STATIC stability and controll,
i.e. it can "fly" with ZERO forvard speed !
Henryk, i really do not know.
More info on bkb-1, from https://www.j2mcl-planeurs.net/dbj2...iles/The_Worlds_Sailplanes_2_(OSTIV_1963).pdf
Plus this one..
Yes the wing tip brakes seem a bit odd...and might be a menace to a beginner.
3 meters more span ( 20 % ) gives glide ratio from 30 => 45 !
Difference between BKB and Bekas-N.
23:1 glide ratio. Self launch capable.
20:1 as a e-version: https://en.wikipedia.org/wiki/Electric_Aircraft_Corporation_ElectraFlyer-ULS
11.2 m span: https://en.wikipedia.org/wiki/Airsport_Song
LAK-17 has 45:1 glideratio..but weighs 245 kg empty : https://en.wikipedia.org/wiki/LAK-17
Sorry..it must be this ( E342 )...I have to check it.
http://airfoiltools.com/airfoil/details?airfoil=e342-il or http://airfoiltools.com/airfoil/details?airfoil=e341-il
I may try to see if Eppler 335 could be used: http://airfoiltools.com/airfoil/details?airfoil=e335-il
Looks like to be one of moment zero foils from E34x series. So bottom, right diagram.
And quote from journal about bkb-1, and problem of other flying wings in gusty condition..
I will try to get in touch with them, they are using carbon rods tech, from Jim.
But - twin boom configuration has beauty in placing wheels on boom, safer prop (there was incidents then prop have not deployed in time). Easier to make and smaller molds - especially, with improved untapered wing by Strojnik .. Almost same as building two gliders in place of one.
Ps. my idea of using same airfoil for tail was wrong, and no one fixed it..
Will try to play with moldless wings, i do have cnc foam cutter..
And post me to gallery of composite wing/ wingtips connectors..
In my virtual experiments I have been using the e337.
That is awesome too: http://airfoiltools.com/airfoil/details?airfoil=e337-il
I was wandering if a 14,2 m ( max 3 seater ) spanning all electric flying wing could have a FBW system...and an autopilot...it might give more customers.
This ought to fly 1 hr at 10 kg/m2 wing loading. It has Eppler 548 ....a 0 moment foil.
How about electrifying Pelican ?
Me not. Have to nice childs.
To narrow cg range, to tricky to fly...
PIOS tendency increased ?
A zero moment isn't essential. In fact you can use just about any airfoil, but low moment is highly beneficial. You are going to need some kind of nonlinear twist to ensure that the stall starts at about 30-40% of the half span. The AoA will then automatically adjust itself for zero moment.
(A bit more complex than that, but want to avoid thread drift again)
I was thinking about twisting just the end piece of the wing..last 20%.
You should have the largest amount of twist at 30-40% of the half-span. That is where the stall will start, leaving the ailerons still effective.
Look up Al Bowers paper on the PRANDTL-D. Why reinvent the wheel---I mean wing? He has already figured it out! The important thing is the general shape of the twist distribution, not the absolute amount of twist.
Out of curiosity, I was just looking at some 20kw-30kw motors.
Have any of you considered that they use liquid cooling? At least the ones I have looked at. That means a radiator, pump, and coolant, which in turn means more weight.
Another thought. If you use "5 gallon size" battery pack that weighs about 100 pounds, you can distribute the batteries to get the desired mass distribution. The motors I was looking at weight about 35 pounds, without cooling system. This is one advantage over a 95 pound IC motor, and you don't have to worry about the CG changing as the batteries are drained.
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