Design and role of jury struts

[JLS]

I can't figure out completely how jury struts work.

I clearly understand that jury struts can help and suppress buckling
of struts in compression (with spar in tension in negative load).
I've calculated deflexion of spar in compression (at +6G in positive load) and
found it of few inches (with 2.5" OD 0.083" wall 6061T6 tube spar). Although nothing
is wrong with that, I'm quite upset with flaps behind rear spar (my design
is with plain flaps and not junkers avid kitfox style flaps) and would like
to have your opinion about jury struts in this case.

Does it alleviate spar deflexion and how much in this case ? (I can't
imagine that jury struts report all their load and make the struts(in tension)
only bend, but it could be the case (why not?)).
If you can share an article, paper or proper explanation of this (I'd like to
have figures for my design and not only (that would be however welcome)
intuition about the phenomenon), it would be of great help.

A definitive answer would be to test in reality loads of the wing but
it's just at the design stage at this time.

note: I made the deflexion calculus with plain spruce spar and it's
much less, so the problem is only with aluminium round spar. Having
greater inertia (bigger spar) isn't an option for me.

[Dana]

Jury struts won't do anything for spar deflection, unless the strut was stronger (or rather stiffer) than the spar itself.

[Airmutt]

Jury struts have two primary purposes. First they serve to stabilize the struts from resonance or vibration. Second, they aid in preventing the struts from buckling under negative loads. If the struts are sufficiently robust, jury struts are not required case in point the Piper Pacer, Colt, and TriPacer.

[JLS]

Thanks for your answer. How to deal with aluminium spar deflexion and plain flaps
and aileron elasticity ? With aluminium and same modulus of elasticity, it seems
there are no other option. Wood would crack in my opinion.

Example Just aircraft Escapade (outback kit here in France):
9307


I'm not a big fan of replicating an existing design but I'm interested in
foldable wings. Perhaps my choice will go to plain spruce spar and forget
foldable wings.
Have you a clue to get control surfaces elasticity with wood and aluminium round
spar, I'd be interested in ?

[JLS]

In these few weeks reviewing my goals, I finally found it more appealing with a single strut on each wing
forgot foldable wings and aluminium round spar, so no worry about jury struts.

9315