Lazy Slat causing unstable approach

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Lazy Slat causing unstable approach

Postby BDA » Thu Apr 08, 2021 2:33 am

Since my first flight I have had the left side inboard slat not come out when the others do.

So the slats on the right come out, and that wing goes up, the left wing does not, so I correct w aileron and the left slat then comes out, and causes over correct.

The first time it happened I was short final 100’ off the ground and thought I was a gonner. Drop a wing when slow ... not good.

So nobody seemed to have any helpful advice (I was told that propwash kept it in) either way, it sucks.

I thought VGs could help, so I put 4 VGs on the outboard end of the lazy slat at 60 mm spacing 5/8” from leading edge.

And just like that - no more lazy slat, it acts just like the other slats now.

Lucky guess works for me!!
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
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Re: Lazy Slat causing unstable approach

Postby Clark in AZ » Thu Apr 08, 2021 10:06 am

Interesting. So, you only have vgs over that slat?

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Re: Lazy Slat causing unstable approach

Postby BDA » Thu Apr 08, 2021 12:27 pm

Yes, and only 4
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
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Re: Lazy Slat causing unstable approach

Postby dkshow » Thu Apr 08, 2021 7:27 pm

Sounds strange, like that one is sticky. My slats come out whenever they want, usually the right first then left but it's never made any noticeable difference or dropped a wing ever. I've got VGs on the outboard half of my wings in front of my ailerons, I may add more this summer.
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Anchorage, Alaska Superstol N445K
Built in NC with Rob Pedersen, Plane Fun Aircraft
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Re: Lazy Slat causing unstable approach

Postby BDA » Thu Apr 08, 2021 11:43 pm

Ya I have checked it for “sticky” about 1,000 times now. Whatever it is, it is def aerodynamic.
I think the wing drop was more overcorrection with the spoiler coming up killing lift then oposite wing slat finally comming out.

They operate normally now. Easy in and out, and deploy at the same time on final.

I just put the covers on my strut attach points, maybe the airflow was weird around those open holes.

You def need VGs in front of the flaps.

When you gonna get that thing out for summer Kieth??
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
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Re: Lazy Slat causing unstable approach

Postby dkshow » Fri Apr 09, 2021 5:26 pm

I'm hoping to get back in the air next week. I've got a couple of little things I want to do like replace my turtle deck. Mine has lasted 5 years and it's time for a fresh one.
Keith Showalter
More Photos at www.keithshowalter.com
Anchorage, Alaska Superstol N445K
Built in NC with Rob Pedersen, Plane Fun Aircraft
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Re: Lazy Slat causing unstable approach

Postby BDA » Sat Apr 10, 2021 2:08 am

You can use my brake if you need
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
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Re: Lazy Slat causing unstable approach

Postby Clark in AZ » Sat Apr 10, 2021 5:55 pm

dkshow wrote:I'm hoping to get back in the air next week. I've got a couple of little things I want to do like replace my turtle deck. Mine has lasted 5 years and it's time for a fresh one.


What's wrong with your turtle deck? Scratches, weathering, or something else? Anything you would do differently on the next one?
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Re: Lazy Slat causing unstable approach

Postby BucF16 » Sun Apr 11, 2021 7:32 am

Hi Clark, Keith's turtle deck is 100% Lexan that he put on a brake for the sides. My Guess is it is crazing after 5 years.
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Re: Lazy Slat causing unstable approach

Postby Clark in AZ » Sun Apr 11, 2021 11:48 am

Ah, that makes sense. Thanks for the response.
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