KJ_Lesnick
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Is it my imagination or does the Su-27 and Su-30 have relatively low roll-rates compared to planes like the F-15?
KJ
KJ
The Flanker has a pretty decent roll-rate per se (270°/s), but due to its dense engines being spaced widely apart it has a high moment of inertia so the rotation takes quite long to build up. Single engine aircraft (F-16, Mirage2000) are most impressive in this regard.
Note that the initial roll rate is always higher, for example the falcon has a 392°/sec initial roll rate but drops (and is controlled by the FBWS) at 270°/sec.
Well, whether it's needed or not, the Su-37 and Su-35BM can indeed use TVC for roll control. The widely-spaced engines would actually add to the torque induced by differential pitching of the nozzles.flateric said:differential TVC is not needed and even could things worse in case of roll maneuver
The control surface layout is generally very similar to the Falcon, with large inboard flaperons (but no ailerons outboard) and differential tail plane movement (tailerons) for roll control.
Neither fighter has ailerons in the strictest sense. Both have large inboard trailing edge devices which perform the functions of both ailerons and flaps (hence "flaperons") while the outboard part of the trailing edge is fixed. As I said, the Falcon and Flanker are based on essentially the same approach in this regard.
Trident said:The T-38 can *theoretically* achieve 720°/s (I think), but only if you keep on rolling long enough, which incidentally provides another good example that the final roll rate may not tell the whole story.
Most airliners use spoilers to kill lift on the wings after landing. In all the times I've flown in commercial jets, I've only seen spoilers deployed after touchdown. I think only a few business aircraft used it as well, the Mitsubishi MU-2 twin turboprop being one example.cosmicpop said:Hi
I don't think the answers to your questions about spoilers are that simple.
Spoilers tend to be used on high-aspect radio wings such as airliners and combat aircraft with low wing-sweep/speed. For example, I think most jet airlines use spoilers wholly or partially for roll control, and combat aircraft such as the Tornado and F-111 during low sweep angles. The SEPECAT Jaguar also uses roll-control spoilers. The thing that most of these aircraft have in common is the use of full-span flaps for lift augmentation so leaving little or no space for ailerons.
As for your third question, I'm sure the designers of those aircraft chose two-third span ailerons/flaps for a number of reasons. Mechanical simplicity (and weight) being one. No need for high-lift double or triple-slotted flaps being another. Also - the most acrobatic aircraft in the world (such as the Su-26, Yak-55 and Extra 300) all use full-span ailerons so there must be something good about it!
James