Swept vs. unswept landing gear

[Kenneth Blackwell]

Jim,

There are at least two design factors that affect the way an airplane touches down (with/without  bouncing). The most important is the fwd/aft location of where the main wheels touch the ground....relative to the c.g. Many designs have the wheels too far farward and tend to porpoise/bounce....especially on concrete/asphalt. The other is the spring rate of the gear strut. You want the strut to be strong enough to take a reasonable bad landing but still be soft enough to absorb the shock.

In the case of swept gear, the sweep usually makes for a softer spring rate...thereby giving the airplane a little softer touch when landing. Then, depending on the location in the fuselage the swept gear may move the wheel contact point a little further back....toward the c.g.

Airplanes with the wheel placed ahead of the wing leading edge will usually be bouncy....especially on hard surfaces. Of course, you can move it back too far and get an airplane that is tippy...especially on grass. If one is flying mostly off grass they will tend to like gear that is placed in a more forward.location while if you fly mostly off hard surfaces, you would like it a little further aft. It's somewhat a compromise......

Cheers,

Ken Blackwell


----- Original Message ----- 
From: JOddino 
To: discussion at nsrca.org
Sent: 5/3/2004 6:40:54 PM 
Subject: Swept vs. unswept landing gear


Recently I started flying the Alliance with its swept landing gear.  I'm really impressed with the way it lands without bouncing.  I notice the Focus LG is not swept.  What kind of experience are people having with swept vs. unswept or has that got anying to do with how the plane sticks to the runway?  I'd like to hear the theories if there are any.
Jim
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20040503/8e04562c/attachment.html