SU27 Flanker control surfaces?
 

Building one from plans which use traditional aileron/elevator configuration. I want to build a scale version but am confused by how the full size actually works with respect to the 'flaperons'. It uses tailerons, has dual slotted flaps inboard, and what are described as outboard flaps where ailerons would normally be. These facts are according to a book Military Aircraft Anatomy. The question is would flaperons coupled with all moving tail surfaces function on a model? I don't know enough about jet aircraft design to know if this is a unique design, or in fact, if the book is correct. Any help out there? Thanks, Bill S.

RE: SU27 Flanker control surfaces?
 

Looking at a cutaway drawing of the Flanker in "International AIR POWER Review" vol 8, the wing outboard of the flaperons is fixed, not a movable surface. There's no hinge line visible for that part of the wing in the photos.. ( Lots of neat color schemes on that one!)
Flaperons per se are generally used on gliders, where camber changing is used for different flight configurations.
For a jet model, they'd probably be overkill.
Flaps alone might be OK, if tailerons are used for lateral control, otherwise flaperons would make sense on a jet, but on the Su the span of the aileron is less than the span of the horizontal, which would have more authority in roll.
The dual-slotted flaps would be a mechanical problem on a model, and another problem to make the back part into flapeons.
Best to use them as single flaps (erons)..
I note the Su-27KUB (carrier version) does have movable outboard surfaces, probably added to assist the approach speed to the carrier.

RE: SU27 Flanker control surfaces?
 

Not your answer, but...
I assume you've seen Harald Huf's remarkable project? http://www.su27projekt.de/

RE: SU27 Flanker control surfaces?
 

In the book I referred to, they do call the outboard portion a 'flap'. I'm never sure just exactly how accurate these drawings are. There may also have been different configs. As far as dual slotted flaps-wouldn't even attempt it! And,yes, Mike I have been following Harold's SU for some time. Good idea though, I'll email him, with all the drawings,etc. he may have the answer. As agile as that plane is supposed to be, it seems odd-no ailerons. The MIG29 apparently has them. Wish I knew where there was a full size sitting around here in the CONUS.

RE: SU27 Flanker control surfaces?
 

According to Harold-THE MAN-, the tailerons provide the bulk of the roll control with the flaperons acting as ailerons only in 'extreme maneuvers', never, he says, for takeoff or landing. The flaps(erons) and L.E. Flaps in normal down position for TO/landings. Thanks for the input!

RE: SU27 Flanker control surfaces?
 

There is only one control surface mounted on the standard Su-27 wings. (flaperons) The only variants that employ seperate ailerons and flaps is the Su-27K and Su-27KUB. (naval variants)

I'm not sure if you've seen Ken Duffy's Flanker site, but IMO, it is the definitive source for Flanker-related info.

http://www.duffeyk.fsnet.co.uk/su-27_variants.html

Dan

RE: SU27 Flanker control surfaces?
 

I did- and still do- refer to Ken Duffey's site. You are right I think about the configurations on the variants, of which I think there are about 15.