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Is this really called an "inverted wing", I've always heard such configurations referred to as "forward swept wings". For reference, see the Russian Su-47. ht

Is this really called an "inverted wing", I've always heard such configurations referred to as "forward swept wings". For reference, see the Russian Su-47. https://en.m.wikipedia.org/wiki/Sukhoi_Su-47 https://en.m.wikipedia.org/wiki/Sukhoi_Su-47 https://en.m.wikipedia.org/wiki/Forward-swept_wing https://en.m.wikipedia.org/wiki/Forward-swept_wing

sandworm101 7y ago
Ya, inverted wing means something else, a wing tuned for inverted flight... at which point it becomes just a normal plane with the pilots seat upside down.
- onion2k 7y ago
  Is that actually a thing? Landings would be terrifying.
  - Stevvo 7y ago
    It's not a thing, however acrobatic aircraft often have symmetrical airfoils, such that they can fly inverted.
    - brandmeyer 7y ago
      > such that they can fly inverted. Make that, such that inverted flight has the same stall margins as normal flight.
      - Stevvo 7y ago
        Right, even a Cub with its flat-bottomed USA-35B will fly inverted, but in terms of angle-of-attack you would have no room for error, and the gravity-fed fuel system is going to cause you some problems too.
Someone 7y ago
FTA, second sentence after the title: ”Its astonishing forward-swept wings were just one of its many bold innovations.” I count 8 occurrences of “forward-swept”, and 4 of “inverted wing”. I think they used ‘inverted wing’ as a synonym to prevent repetition of a fairly long term. It also is quite possible that the editor, not the writer of the article, chose the article’s title, picking the shorter and, arguably, ‘easier’ term.
djsumdog 7y ago
I guess there's not much information on the Su47 since it was military, USSR, etc. The X-29 required several flight computers to make micro adjustments to keep the plane stable. I wonder if the Russians had to design something similar with the X-29 .. and if not, how did they keep it stable?
- baybal2 7y ago
  > how did they keep it stable? I don't see anything unstable there. It's surely very long, and the wing is way behind the centre of mass, so the centre of aerodynamic forces will be behind it too. Cannards look to be put way ahead of centre of mass too.
  - nwallin 7y ago
    They're fairly unstable. The trouble is that at the wingtips, if the wing twists up, aerodynamics forces tend to push it more up. So there's a positive feedback loop. Another problem is that if you yaw slightly, the yawed backward wing gets more straight on airflow, and the forward wing gets less, causing a stronger yaw force. Again, positive feedback loop.
    - Bendingo 7y ago
      > Another problem is that if you yaw slightly, the yawed backward wing gets more straight on airflow, and the forward wing gets less, causing a stronger yaw force According to geometry, this problem must also occur with conventional backward swept wings.
      - p_l 7y ago
        The geometry makes forward swept wing destabilize further, while classic design self-stabilizes (or oscillates). That said, slight forward swept had been used for years in many planes, it's the more extreme angles that get the fun mentions.
sdinsn 7y ago
The Su-47 is discussed in the article.

sandworm101 7y ago

Ya, inverted wing means something else, a wing tuned for inverted flight... at which point it becomes just a normal plane with the pilots seat upside down.

onion2k 7y ago
Is that actually a thing? Landings would be terrifying.
- Stevvo 7y ago
  It's not a thing, however acrobatic aircraft often have symmetrical airfoils, such that they can fly inverted.
  - brandmeyer 7y ago
    > such that they can fly inverted. Make that, such that inverted flight has the same stall margins as normal flight.
    - Stevvo 7y ago
      Right, even a Cub with its flat-bottomed USA-35B will fly inverted, but in terms of angle-of-attack you would have no room for error, and the gravity-fed fuel system is going to cause you some problems too.

Someone 7y ago

FTA, second sentence after the title: ”Its astonishing forward-swept wings were just one of its many bold innovations.” I count 8 occurrences of “forward-swept”, and 4 of “inverted wing”. I think they used ‘inverted wing’ as a synonym to prevent repetition of a fairly long term. It also is quite possible that the editor, not the writer of the article, chose the article’s title, picking the shorter and, arguably, ‘easier’ term.

djsumdog 7y ago

I guess there's not much information on the Su47 since it was military, USSR, etc. The X-29 required several flight computers to make micro adjustments to keep the plane stable. I wonder if the Russians had to design something similar with the X-29 .. and if not, how did they keep it stable?

baybal2 7y ago
> how did they keep it stable? I don't see anything unstable there. It's surely very long, and the wing is way behind the centre of mass, so the centre of aerodynamic forces will be behind it too. Cannards look to be put way ahead of centre of mass too.
- nwallin 7y ago
  They're fairly unstable. The trouble is that at the wingtips, if the wing twists up, aerodynamics forces tend to push it more up. So there's a positive feedback loop. Another problem is that if you yaw slightly, the yawed backward wing gets more straight on airflow, and the forward wing gets less, causing a stronger yaw force. Again, positive feedback loop.
  - Bendingo 7y ago
    > Another problem is that if you yaw slightly, the yawed backward wing gets more straight on airflow, and the forward wing gets less, causing a stronger yaw force According to geometry, this problem must also occur with conventional backward swept wings.
    - p_l 7y ago
      The geometry makes forward swept wing destabilize further, while classic design self-stabilizes (or oscillates). That said, slight forward swept had been used for years in many planes, it's the more extreme angles that get the fun mentions.

sdinsn 7y ago

The Su-47 is discussed in the article.