"Tarver Engineering" wrote...

Ed did not address the use of spoiler flap as used to cancel adverse Yaw,
produced by roll steering. Ed's description of the spoiler is refers only
to a spolier flap in a speedbrake configuration and while textbook in
nature, has been false for airliners since the 707; except twins. (engine
out regulations for twins require a tall tail, so the mechinisation of a
spoiler flap carrys too large a weight penalty to be practical)

I don't think any of us have ever seen any documentation in any book or
technical publication that refers to a "spoiler flap" -- so far, the term
appears to have been created by Tarver, here in the newsgroup. OTOH, through
the years I have seen several just-as-ridiculous descriptions of aeronautical
equipment and their [alleged] functions in the popular press (newspapers and
non-technical magazines, apparently written by people not familiar with
airplanes.

The statement "a spoiler flap in a speedbrake configuration and while textbook
in nature, has been false for airliners since the 707; except twins" sounds like
a new Tarverism, worthy of archiving. Its actual meaning escapes me, though the
misinterpretations and misinformation that could easily be drawn from it by
people looking for information are numerous. Just a few examples:

I have never read about "a spoiler flap in a speedbrake configuration" in
any textbook. Anyone else?

From "false for airliners since the 707; except twins" it is possible to
infer that the L-1011, DC-10, MD-11, 747, and other 3- and 4-engine airliners do
not have spoilers or speedbrakes. Of course, we all know that is false.

The statement that "engine out regulations for twins require a tall tail" is
clearly false in the general case, as evidenced by the DC-9, MD-80, and B-717,
as well as numerous business jets with fuselage-mounted engines.

And finally, "...require a tall tail, so the mechinisation of a spoiler flap
carrys too large a weight penalty to be practical" makes no sense whatsoever,
because: (1) we don't yet know what a "spoiler flap" is; (2) spoilers
"mechani[zed]" as speedbrakes are in fact used on virtually every modern
airliner; and (3) the height of an airplane's tail has no bearing on whether or
not spoilers "mechani[zed]" as speedbrakes are practical -- they are apparent on
both tall-tail (e.g., 777) and short-tail (e.g., MD-80) airliners.