Airplanes by Design – Grumman X-29

January 25, 2012 in Airplane with 6 Comments

This X-29 research aircraft at NASA Dryden Flight Research Center allows us to see a very unique wing as we wrap up this month long review of aircraft wing design characteristics with three more: dihedral angle, sweep, and twist.

Grumman X-29 Forward Swept Wing

Dihedral Angle

The angle between the aircraft’s xy-plane (parallel to the horizon when viewed from the front) and the wing is known as the dihedral angle.  However, the position of the wing relative to the vertical center of gravity also results in a dihedral effect. High wing aircraft have a higher effective dihedral than low wing aircraft as a result of the fuselage’s effect on airflow. Dihedral has a significant impact on directional stability.

The X-29 has little or no dihedral angle, but since it’s wings are mounted low on the fuselage this gives it an anhedral (or destabilizing) effect.
Grumman X-29 Forward Swept Wing

 

Wing Sweep

Grumman X-29 Forward Swept Wing

The shadow cast by the aircraft in this photo clearly highlights the unique wing sweep characteristic of the X-29, with its forward swept wing. Some gliders have wings that are swept slightly forward as well.

 

Wing Twist

Grumman X-29 Forward Swept Wing

Close examination of this photo reveals the X-29′s wing twist. The root of the wing angles down, while the wing tip has a more positive angle of incidence.  The X-29 was also uniquely designed with a special composite laminate that affected the twist of the wing caused by aerodynamic forces. The forces would have caused the wing to have a divergent twist, but the composite laminate reduced this.

Click here to read more about this airplane on the NASA Dryden website, or view more NASA photos of the X-29 here.

Airplanes by Design features photographs of aircraft from a test pilot perspective, highlighting aeronautical engineering characteristics and flight test facts. To see all of the these pictures (and many more of this aircraft and it’s unique design characteristics), click here. You will always be able to access any of these pictures by selecting the Flickr icon in the top menu bar.

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  • Jason C

    I have more pics of the a/c at the National Museum of the USAF. Let me know if you want copies.

  • http://www.multiplyleadership.com Mark Jones Jr.

    Do you have a link I could share?

  • Jason C

    Not other than the museum link. These are pics I took walking around the airplane (no barriers)  :)

  • Jason C

    I set up a temp ftp and sent you the login info.

  • Jason C

    Another thought I had, not specifically related to the X-29 but all so-called x-planes, these are not optimized configurations. In the case of the X-29, in terms of airframe and some sub-systems parts come from the F/A-18, F-5 and F-16. 
    Data collected from these airplanes provide an important baseline to develop and test optimized configurations.
    Wanted to know what you thought. 

  • http://www.multiplyleadership.com Mark Jones Jr.

    That’s a fascinating observation.  I do think that we see a lot of commonalities in later aircraft design that originate in these X-planes. For example X-15 and SR-71 look the the nose/fuselage design have a very common ancestry.