REFLECTOR: Aileron Rigging (Reflexing)

Peter Braswell peter.braswell at gmail.com
Thu Apr 26 14:16:49 CDT 2012


I'm familiar with reflexing the ailerons from my days flying composite high
performance R/C gliders.  The idea is that you change the under camber of
the wing, reducing drag at higher speed making the plane more efficient.
 The tradeoff was stability and stall speed.  SS went up.

With model airplanes, reflex is pretty easy to achieve as the control
surfaces are individually controlled by servos … effectively fly by wire.

I couldn't imagine the mechanical linkages that you'd have to come up with
to pull reflex off in a Velocity, though I'm not terribly mechanically
inclined so I may just lack imagination.

>From a practical perspective though, the added complexity / weight for the
theoretical increase in top-end speed (in my opinion) has negligible value.

-Peter

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On Thu, Apr 26, 2012 at 2:51 PM, John Dibble <aminetech at bluefrog.com> wrote:

>  I think decreasing the main wing lift will cause the main wing to sink
> relative to the canard, increasing the AOA and require the elevator be
> further up to keep flying level.  For my plane that would mean more drag
> since my elevator is up at cruise anyway.
>
> John
>
> On 4/26/2012 10:57 AM, Lawrence Epstein wrote:
>
> I am not convinced that the concept of reflexed ailerons reducing *total *drag
> applies to canard aircraft.
>
> Part of the drag reduction is, as previously mentioned, decreasing the AOA
> of the wing, therefore decreasing lift and therefore drag. The difference
> is, in a conventional (aft tail/elevators) this would require *less *lift
> from the elevators (pushing the tail down to compensate for decreased lift)
> and *decreasing *the drag for the elevator/rear "wing" as well. This is
> the same reason conventional airplanes fly faster with aft CG.
>
> In a canard aircraft, decreasing the overall lift of the main wing would
> require deflecting the elevators *down*, thereby *increasing *the lift of
> the canard and increasing the drag created by the *forward *wing.
>
> I'm not saying that the net wouldn't be less drag, just that it would need
> to be determined (experimentally or if someone knows how to do the
> calculations).
>
> Larry Epstein
>
>  On Thu, Apr 26, 2012 at 11:40 AM, John Dibble <aminetech at bluefrog.com>wrote:
>
>  Without knowing it, I think I've already done the testing for you.  When
> I bought my plane the ailerons were 1/4" up.  I flew that way several years
> with no problems.  However I had nothing to compare with.  Then after the
> discussion several months ago, I changed mine to 1/16" up.  That resulted
> in a more sluggish response, but more stable tracking.  I think I picked up
> a few knots, which is contrary to what your article is saying.  I think
> Larry Coen's comments that a neutral position (when in flight) will give
> the least drag is the best explanation.  I see no concerns if you want to
> experiment  and position the ailerons up.  It's more responsive, which I
> like .  However I prefer the stability (and greater speed?) more.
>
> John
>
> On 4/26/2012 9:58 AM, Ron VelocityXLFG wrote:
>
>   http://www.angelfire.com/on/dragonflyaircraft/reflexing.html
>
> I know there are people with way more understanding of this than me . I
> only entertain the idea
> because the web sit speaks of gaining 10- 60 knots in theory . Reflexing
> the ailerons
> would be a fairly easy  modification .  If you could gain this kind of
> speed with the same HP
> and set the system up so as to remove the reflex of the ailerons as the
> plane slows down why not
> give it a try.
>
> Yes deep stall is very possible and maybe the whole reason not to  do this
> but what if you could
> rig the system to remove the reflex in the system quickly and would also
> automatically removed
> the reflex  if the plane is under some predetermined speed. With a gain of
> 10 knots with the same
> HP sounds real enticing.
>
> No I am not trying this just entertaining the idea. I do not own a
> Parachute so I will only entertain the idea
> for now. Has any one looked into this and would like to share.
>
> Ron
>
>
>
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