Strake aerodynamics

[nadt770]

Are the strakes just fuel tanks? I've read that the inboard wing and strakes on these aircraft do very little lifting. What happens aerodynamically if the strakes are removed? Assuming that room for fuselage tanks could be found would the reduction in parasitic drag from removal of the strakes be worth it?

[TMann]

And put what there?

The strakes are wing area that are (as in most planes) used to store fuel.

The most inboard area is accessable from the interior of the fuselage and is used for baggage, elbow room etc.

 

We've had discussion in the past about the aerodynamic qualities of the strakes and the fact that the flat surfaces don't appear to be optimal in this respect. The bottom line is that any effort to try to improve this area would be a waste of time. The strakes are in the wake of the canard.

 

For a reference check out this discussion thread.

[chasingmars]

Are the strakes just fuel tanks? I've read that the inboard wing and strakes on these aircraft do very little lifting. What happens aerodynamically if the strakes are removed? Assuming that room for fuselage tanks could be found would the reduction in parasitic drag from removal of the strakes be worth it?

If you model them as flat plates, which isn't entirely accurate, it generates very little lift *at zero angle of attack*, as angle of attack increases, so does lift. Eliminating the strakes removes a fairly large *roughly* flat plate lifting surface forward of the M.A.C., moving the centre of lift back, and I'd make an educated guess that this would have quite a significant effect on the aerodynamics of the aircraft at high angle of attack (i.e. approaching stall). But because of interactions with the rest of the wing, it's not clear on the extent and details.

 

similar aerodynamic concerns arise if you make them lifting surfaces, moreover if you do make them full foils, you don't gain as much as you might think as you exacerbate an existing problem of the canard design, that being poor span load distribution, reducing the lifting efficiency of the wing, ironically, a poor foil inboard means the reduced inboard lifting effectiveness in cruise can actually increase the aircraft's overall efficiency factor (all else equal which isn't the case, the parasitic drag here makes this a losing game)

[michaelj]

I am a by no means an expert on aerodynamics but I do have some knowledge of engineering principles. I feel safe to save that an attempt to remove the strakes would seriously compromise the ability of the center spar and wings to resist tearing itself off the fuselage in flight. When I fly loaded down for a few days I would prefer to have more baggage space. The Cozy Girrls made their strakes bigger.

[Wayne Hicks]

Yall are missing the other point -- structural. The center section spar is a noodle without the strakes. (Think triangles.) Even if you located the fuel bay(s) elsewhere in the fuselage, you'd still need to stiffen the spar. My understanding from Nat who got it from Burt is that the strakes on the RAF designs and derivatives are flat to make them easier to build. There was very little aerodynamics fore-thought or after-thought.

[michaelj]

Exactly my point. In addition, if you attempt to make the strakes more efficient lift generators disaster could be the result. The center of lift would change throwing off the canard/wing balance. "If it's not broken, don't fix it."