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Newbie Joined: Jun 15, 2007 Posts: 12 Status: Offline

Welcome

I'm here new and I'd like to say "hello" to everybody Smile

(well my English isn't as good as I want it to be Smile

).

I would like you to explain me why the forward sweept wing use to be (well I hope so) better option for very sharp turns. I've read that at high AoAs the wing's controll surfaces (like ailerons) remain still effective. I found this picture, which demonstrates the airflow at sweept wing and forward-sweept wing:

Can someone explain me why ailerons are still efective ?? is it somehow connected with the reverse airflow ?? (and the direction of lift drop)

And my second question Smile

- what's going on with Su 47 - is it going to be produced ?? ever
I would be grateful if you could answer my questions

Regards

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Hey man. Good question. I found some info on http://www.flymig.com/aircraft/Su-47/ and http://en.wikipedia.org/wiki/Sukhoi_Su-47 (tho i am not sure on this as a refence). Here is what the first one says about the ford-sweept wings..

Quote:

The aircraft makes use of forward-swept wings allowing superb maneuverability and operation at angles of attack up to 45° or more. The advantages of forward sweep have long been known as such wings offer lower wave drag, reduced bending moments, and delayed stall when compared to more traditional wing shapes.
Unfortunately, forward sweep also induces significant wing twist that would shear most wings off the aircraft. To solve this problem, the Su-47 makes use of composite materials carefully tailored to resist twisting while still allowing the wing to bend for improved aerodynamic behavior.

And from wikipedia..
[/quote]The forward-swept midwing gives the unconventional (and characteristic) appearance of the Su-47. A substantial part of the lift generated by the forward-swept wing occurs at the inner portion of the wingspan. The lift is not restricted by wingtip stall. The ailerons - the wing's control surfaces - remain effective at the highest angles of attack, and controllability of the aircraft is retained even in the event of airflow separating from the remainder of the wings' surface.

The wing panels are constructed of nearly 90% composites. The forward-swept midwing has a high aspect ratio, which contributes to long-range performance. The leading-edge root extensions blend smoothly to the wing panels, which are fitted with deflectable slats on the leading edge; flaps and ailerons on the trailing edge. The all-moving and small-area trapezoidal canards are connected to the leading-edge root extensions.

The downside of such a wing design is that it produces strong rotational forces that try to twist the wings off, especially at high speeds. This twisting necessitates the use of a large amount of composites in order to increase the strength and durability of the wing. Despite this, the plane was initially limited to Mach 1.6. Recent engineering modifications have raised this limit, but the new limit has not been specified.
[/quote]

Hope this helps ya.

Elite 1K Joined: Aug 19, 2004 Posts: 1092

The picture on the right show the ailerons on the main wing getting lots of airflow and hence lots of control power. The one of the left shows the elevators getting lots of airflow and hence lots of control power as well. That's the idea behind the two pictures. I'm not exactly up on the FSW concept, so I won't comment any further.

Enthusiast Joined: Jun 28, 2007 Posts: 26 Status: Offline

The forward swept wing gives better handling at lower speeds as far as I know with a lower stall speed, but it's a lot more strenuous on the plane as a whole.

Enthusiast Joined: Aug 18, 2007 Posts: 97 Status: Offline

Forward swept wings also add high-subsonic drag as you approach the sound barrier (one of the reasons the U.S. abandoned the concept after the X-29). Though their low speed handling and dogfight qualities are excellent. A variable sweep wing could solve that.

See this concept - http://www.area51zone.com/aircraft/switchblade.shtml
This is LOOSELY based on a concept that Northrup-Grumman put a patent out on, so take it with a grain of salt (still the idea is interesting)!

Enthusiast Joined: Aug 18, 2007 Posts: 97 Status: Offline

You also might want to check out a slightly more credible (and more in depth) web site on the Northrup-Grumman switchblade here http://www.air-attack.com/page.php?pid=9
It also covers a little bit about your original question about the ailerons (although I'm not sure if it will answer it to your satisfaction) Sad

And I seriously doubt if the Su-47 will be developed further, other Su-27 derivatives seem much more likely.

One thing that is not frequently mentioned, is that the computer simulations closely match the actual performance parameters of the finish product. The inability of the computer simulations to match actual performance, is the main reason the T-10/Su-27 took so long to put into operational status. The instability problems of the T-10/Su-27 caused four crashes and the lives of two test pilots. A second driving force was to increase the knowledge base on carbon fiber composits. This was necessary for a lightweight fully functional forward swept wings.
This is considerable debate on what sort of battle damage forward swept wings could tolerate compared to rearward swept wings.
I also doubt that this aircraft will go beyond an experimental phase. At a MTOW of over 77,000 pounds, this goes completely against Russian aircraft philosophies on fighter design.
West Germany produced the business jet, the "Hansa 320" jet. It boasted all the usual things about forward swept wings but was not continued or duplicated.

FlightDreamz wrote:

this concept -
http://www.area51zone.com/aircraft/switchblade.shtml
This is LOOSELY based on a concept that Northrup-Grumman put a patent out on, so take it with a grain of salt (still the idea is interesting)!

Maybe to keep Revell or Mattel from duplicating it!

Adrian

Some intresting reading on FSW aircraft to include some photos/drawings of different FSW concepts.

http://www.strange-mecha.com/aircraft/FSW/US-FSW.htm

http://oea.larc.nasa.gov/PAIS/Partners/X_29.html

Two Cents

There are many major German WWII aviation innovations that are used in the modern world, but FSW aircraft are not zooming around the skies on a regular basis... There must not be enough checks in the "pros" column versus the "cons" column... Yet... Wink

Senior member Joined: Jul 01, 2007 Posts: 368

Looks like a zippy little personal jet.

Elite 1K Joined: May 26, 2005 Posts: 1152

I can see the family resemblance in the inlet and tail to the X-31. Rockwell gets involved in some weird projects.

All the big $$ is in R&D. Think of it....

Lots of $$ and you only have to build 2 or 3 aircraft!? If they don't work Congress won't bat an eye because they were "experimental" Wink

Then it's on again to the next project...

Enthusiast Joined: Aug 18, 2007 Posts: 97 Status: Offline

Did anyone catch "Future Dogfights" on the History Channel this past friday (May 9th)? The program showed some "interesting" computer animation of stealthy Su-47 derivatives battling F-22 Raptors.

Enthusiast Joined: Aug 10, 2008 Posts: 66 Status: Offline

This is a really old topic, but since it's still fairly high up on the first page, there can't be much harm in posting a reply.

You know, the Su-47 Firkin seems like it would be better than the Flanker line up in combat potential if properly developed. I've read that it's RCS is on the order of 0.3 square meters, which is significantly smaller than that of any Flanker model. The forward swept wing does provide advantages in maneuverability, which is what the Flanker is known for. Adding 3-D thrust vectoring to the Firkin would help, too. Put the Irbis-E radar in there and you're good to go. I don't know how much the Su-47 costs to build and mantain, but if it's much more than the Flankers then I could see why it wouldn't be developed further.

The T-50 would presumably be better than either the Flankers or the Firkin, though.

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