X8 flying wing

looks like a lovely thing, but...

...from what I casually read about it's smaller brother (the Falcon EPO) it suffers from some interesting flight dynamics at the edge of it's flight envelope. (http://www.rcgroups.com/forums/showthread.php?t=1288385). People are reporting that it quickly drops into a potentially unrecoverable spin when it stalls.

Interestingly, these are similar flight dynamics that I discovered when I was X-Planing with my HDwing concept (which, sadly is still a concept at this stage), so I think they are characteristics of flying wings generally and perhaps poorly designed ones in particular. Be careful with this beast before you load it up with all your expensive autopilots and FPV gear!

There are several things I have done to help mitigate these characteristics on my X-Plane model. Firstly I was trying to make it work as a glider, but abandoned it because adding a motor and propellor increases the rigidity in pitch without having to have extreme wing washout,

I have also gone to wide-chord tip flaperons as opposed to full-span flaperons that are popular on flying wings. I guess this is because it makes them easy to control and to locate the servos - I haven't made mine yet!. This revision is to increase the efficiency of the wing by, in effect, having variable wash-out

Additionally, I have increased the wing sweep. The wing tips of a flying wing are analogous to the tailplane of a conventional aircraft - the tips are pushing down to counteract the forward CoG and to give positive pitch stability. By increasing the sweep angle, you increase the moment arm that the tips are working with, so you can get away with less washout and, in theory, end up with a more efficient wing.

Just a tuppence or two from my work, FWIW.

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Comments

Jason Wise December 14, 2011 at 10:25pm

Andrew, this isnt your bird, so dont get the point of your post(or attempted thread jack) about what you have done as this X8 is no throw together and will be amazing value for money

http://www.bevrc.com/ has had the X5 or a while now and its flys fine
Moderator

Robert Krogh (hooks) December 14, 2011 at 10:23pm
Andrew Rabbitt December 14, 2011 at 7:53pm

PS: when I mean rigidity in pitch, I'm refering to gyroscopic rigidity that the spinning propellor/motor adds.
Andrew Rabbitt December 14, 2011 at 7:51pm

looks like a lovely thing, but...

...from what I casually read about it's smaller brother (the Falcon EPO) it suffers from some interesting flight dynamics at the edge of it's flight envelope. (http://www.rcgroups.com/forums/showthread.php?t=1288385). People are reporting that it quickly drops into a potentially unrecoverable spin when it stalls.

Interestingly, these are similar flight dynamics that I discovered when I was X-Planing with my HDwing concept (which, sadly is still a concept at this stage), so I think they are characteristics of flying wings generally and perhaps poorly designed ones in particular. Be careful with this beast before you load it up with all your expensive autopilots and FPV gear!

There are several things I have done to help mitigate these characteristics on my X-Plane model. Firstly I was trying to make it work as a glider, but abandoned it because adding a motor and propellor increases the rigidity in pitch without having to have extreme wing washout,

I have also gone to wide-chord tip flaperons as opposed to full-span flaperons that are popular on flying wings. I guess this is because it makes them easy to control and to locate the servos - I haven't made mine yet!. This revision is to increase the efficiency of the wing by, in effect, having variable wash-out

Additionally, I have increased the wing sweep. The wing tips of a flying wing are analogous to the tailplane of a conventional aircraft - the tips are pushing down to counteract the forward CoG and to give positive pitch stability. By increasing the sweep angle, you increase the moment arm that the tips are working with, so you can get away with less washout and, in theory, end up with a more efficient wing.

Just a tuppence or two from my work, FWIW.
T3

Rory Paul December 14, 2011 at 5:56pm

Nice...I want one too! But then again there is a lot of stuff I want at the moment...
Jeffrey Torella December 14, 2011 at 2:49pm

thank you
Amit December 14, 2011 at 11:50am

When and where can i buy?
Moderator

Robert Krogh (hooks) December 14, 2011 at 10:23am

About price, I'm sure the price would be within hobby level. I Will try get more details and pictures.
Moderator

Gary Mortimer December 14, 2011 at 9:45am

Now we are talking! Very nice.
tycinis December 14, 2011 at 5:21am

@jasin Wise : Thanks for the link , very nice wing !

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