Why doesn't the Super Hornet have canards?

[Henry J Cobb]

Why does the Super Hornet have leading edge root extensions (LERXs) instead of
adjustable canards?

Is it an area-rule thing or did they worry about changing the shape too much
to get past Congress?

-HJC

[Thomas Schoene]

Henry J Cobb wrote:
> Why does the Super Hornet have leading edge root extensions (LERXs)
> instead of adjustable canards?
>
> Is it an area-rule thing or did they worry about changing the shape
> too much to get past Congress?

It's just a matter of finding the optimium location for the canards. The
standard US position is that their ideal position is on someone else's
aircraft.

Simply, the Super Hornet has no need of canards. They would just complicate
the design without offering any obvious advantage. They certianly woudl
have driven up development costs and complicated the RCS reduction effort
(more moving fins means more hard to conceal flat surfaces).

--
Tom Schoene Replace "invalid" with "net" to e-mail
"Our country, right or wrong. When right, to be kept right, when
wrong to be put right." - Senator Carl Schurz, 1872

[WaltBJ]

It is my understanding that the LEX on the 16 and the 18 contribute
vertex-enhanced lift. I dimly remember reading about the many hours of
wind-tunnel testing to determine the optimum shape for the 16. Also,
powered canards need a power source and more plumbing.
Walt BJ

[WaltBJ]

AAARRGGH! In previous message read vOrtex for vertex. Sorry - too
quick on the 'post' button. (Magneto-enhanced lift? I'll have to think
about that . . .)
Walt BJ

[Henry J Cobb]

Thomas Schoene wrote:
> Simply, the Super Hornet has no need of canards. They would just complicate
> the design without offering any obvious advantage. They certianly woudl
> have driven up development costs and complicated the RCS reduction effort
> (more moving fins means more hard to conceal flat surfaces).

Finally found a good reference for this.

http://www.aerospaceweb.org/question/planes/q0176.shtml
> The benefits of these vortices can be appreciated when one realizes that
> nearly all current military aircraft designs incorporate leading edge
> extensions and/or canards that perform much the same function.
....
> Instead of fences, the F-18E/F makes use of vents located near the junction
> of the LEX and main wing. These vents automatically open at high angle of
> attack allowing air to flow over the inner wing. This additional air flow
> interacts with the LEX vortex to delay vortex bursting in much the same
> manner as the fence did.

So it has LEX vents instead of adjustable canards to deal with high AoAs.

-HJC

[Woody Beal]

On 6/29/04 22:02, in article , "Henry J Cobb"
> wrote:

> Thomas Schoene wrote:
>> Simply, the Super Hornet has no need of canards. They would just complicate
>> the design without offering any obvious advantage. They certianly woudl
>> have driven up development costs and complicated the RCS reduction effort
>> (more moving fins means more hard to conceal flat surfaces).
>
> Finally found a good reference for this.
>
> http://www.aerospaceweb.org/question/planes/q0176.shtml
>> The benefits of these vortices can be appreciated when one realizes that
>> nearly all current military aircraft designs incorporate leading edge
>> extensions and/or canards that perform much the same function.
> ...
>> Instead of fences, the F-18E/F makes use of vents located near the junction
>> of the LEX and main wing. These vents automatically open at high angle of
>> attack allowing air to flow over the inner wing. This additional air flow
>> interacts with the LEX vortex to delay vortex bursting in much the same
>> manner as the fence did.
>
> So it has LEX vents instead of adjustable canards to deal with high AoAs.
>
> -HJC

Not really. The LEX vents on the E/F are there to perform the function that
the fences perform on the A/B/C/D--i.e. Reducing LEX vortex buffet that puts
undue stress on the tail.

Tom's initial response was to say that the high AOA capability of the Hornet
(especially with some of the latest flight control software upgrades) was
sufficient so as not to require canards on the E/F.

--Woody