Stall Strip Location

[Lrn2Fly]

Did a transition training flight for a very nice guy who just bought a '76 "F" model, and I ran into something that grabbed my attention. This plane had a few non-typical Mooney items such as quadrant controls and plenty of additional unmarked switches.  However, the stall strips on his plane (one/side) are located halfway out the wing on the leading edge, not in the traditional location near the root.  I've flown every type of Mooney, but I have never seen this configuration before.  Is this something the factory did that year, and if so, is there any documentation out there on it?

The stall series I put him through did not reveal anything abnormal for a typical Mooney, but the stall strip being so far away from the root really caught my eye.

[Bryan]

I think the stall strips were installed at the factory custom to every Mooney that came off the line. I have also heard of planes where the strips were removed and and not installed back in the same spot after paint which caused the plane to stall differently than before.

[DonMuncy]

It is my understanding that the plane is test flown with the stall strips taped on the wing. Then dependent on its stall characteristics, they move the stall strips around until it stalls straight ahead. The stall strips are then fixed in the proper place. Since that involves screw holes, I have a hard time believing a paint shop could or would install them in a different place.

[ArtVandelay]

Mine are definitely not at the root, on the pilot side, it’s about halfway between stall vane and pitot tube.


Tom

[Hank]

Ditto on stall strip location, they are attached after test flights with tape to determine proper location. Many Mooneys have quadrant controls, up through 1977 or 78 Js; not sure when in the 60s that started.

[Marauder]

My stall strips are outside of the landing gear. 1975 F






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[MooneyMitch]

Stall strip location is indeed located per test flights at factory.  This is discussed by Bill Wheat while filming Boots On The Ground.

Also another very interesting topic recorded in the movie, is Bill’s description of how the inner wing wedge to fuselage came to be !!  Educational and funny!

Both entertaining and educational in the movie, is Bill’s story regarding the what’s and why’s of the famous Mooney empennage! It’s not really on backwards   Thank you Mr Terrible!! 

[Shadrach]

6 hours ago, Lrn2Fly said:

Did a transition training flight for a very nice guy who just bought a '76 "F" model, and I ran into something that grabbed my attention. This plane had a few non-typical Mooney items such as quadrant controls and plenty of additional unmarked switches.  However, the stall strips on his plane (one/side) are located halfway out the wing on the leading edge, not in the traditional location near the root.  I've flown every type of Mooney, but I have never seen this configuration before.  Is this something the factory did that year, and if so, is there any documentation out there on it?

The stall series I put him through did not reveal anything abnormal for a typical Mooney, but the stall strip being so far away from the root really caught my eye.

The strips on my plane are not near the root.

[Yetti]

75F about a third of the way out on the wing from the root.

[75M20F]

75F outside the second seam on the wing


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[M20F]

Mine are about same as Maurader’s but 67F with the twisted wing.  You definitely wanted want them away from the root to lessen the severity of the stall. 

[PT20J]

Purpose of the strips is to minimize rolling moment. They have to be outboard far enough to have a useable moment arm, but not so far as to affect aileron effectiveness. 

[Hank]

2 hours ago, PT20J said:

Purpose of the strips is to minimize rolling moment. They have to be outboard far enough to have a useable moment arm, but not so far as to affect aileron effectiveness. 

And here I thought it was to guarantee that the wing in front of the horizontal stabilizer stalled deeply while the ailerons were still flying, so that the turbulent air would hit the tail and make the yoke vibrate while the wing was still producing lots of lift.

[PT20J]

7 hours ago, Hank said:

And here I thought it was to guarantee that the wing in front of the horizontal stabilizer stalled deeply while the ailerons were still flying, so that the turbulent air would hit the tail and make the yoke vibrate while the wing was still producing lots of lift.

A wing with good stall characteristics stalls first at the root to allow continued aileron effectiveness, minimizes the roll off during the stall, and provides aerodynamic warning of the stall (buffeting). A rectangular wing planform naturally stalls at the roots first. Tapered wings as on a Mooney tend to stall at the tips first. Three common methods for correcting this are twisting the wing (washout) so that the tips fly at a lower angle of attack, using different airfoil shapes and thicknesses at the root and tip to achieve the same effect, and stall strips to force the root to stall first. Mooney uses a combination of airfoil changes and stall strips. 

The strips work by causing flow separation at high angles of attack which stalls the wing section behind the strip. This has the added benefit of creating turbulence over that portion of the wing, and the abrupt ends of the strips create vortices that may impact the tail. Both effects provide the desirable aerodynamic warning of the impending stall.

My comment about the roll control purpose of the strips was based in conversations with Rob McDonnell, VP of Engineering, in 1991. But, it also makes sense based on the the location of the strips along the wing. If the purpose of the strips was solely to get the root to stall first - or create turbulence over the tail - the strips would be located closer to the root of the wing as is more commonly done.

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[Hank]

It's a little hard to see, but for the OP, my stall strips are just outside the landing gear on both wings.

[MB65E]

On 3/7/2019 at 10:53 AM, 75M20F said:

75F outside the second seam on the wing


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Nice OSH stickers!!!

-Matt