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Mackey Slats installation info

D

dwm

Registered User
Hello guys,
can somebody with Mackey Slats tell me how much the slats should be open in the maximum opening position? as I have to make a hole for the opening limit and I can not find the paper with the instruction. I think it was about 2" or 2.5" open but I am not sure.

Thank you in advance for your help!.
 
If nobody answers first I’ll be home tonight and can take whatever measurements you need. Here are a couple of pics. We modified a couple of stops to allow gust locks at each slat. Highly recommended!
 

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I have been asking this same question for years.

Anecdotal evidence suggests a 7-to-1 intake-to-exit (which comes out to ~2.5" gap between the rear of the slat and the top of the wing), but the placement of the slat in relation to the wing bottom also seems to influence the effectiveness of the slat.

The slat hanger stop looks similar to this, and I believe some generations of the slat hanger did not come with pre drilled holes for the stop bolt:

SlatStop.png

(thanks to Ted for letting me take 1 million detailed photos over the years of my favorite airplane of all time)
 

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Example of a hanger supplied without a stop hole pre-drilled:

HangerNoHole.png
 

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Mike probably drilled mine when I was on a different task. Where the stops are located will be determined by where you locate the slat leading edge relative to bottom of wing.
 
I got the answer from Jane Bryson from Backcountry Super Cubs, the number is 2 7/8”.


Sent from my iPhone using SuperCub.Org
 
The instructions say:

After you have completed screwing all the brackets down, cut a few pieces of wood 2 7/8" (2.875) thick. Place them under the trailing edge of the slat. This will set how much the slats can open.
 
This is from the instructions with the set I installed.

"After you have attached all of your hangers you need to locate the stops. The stops only allow the slat to rotate upward 1 ¾”. This means you will want to cut a few pieces of wood 1 ¾”” thick. Set the wood blocks between the leading edge skin and the trailing edge of the slat. Then you are going to hold the smallest bushing that came with the slats in the stop position as seen in the photos. Using the nylon bushing as a template, drill through the bushing center and through the hanger arm. Install these stops with the screws provided."
 
Interesting. Mine open 2-7/8”. I just measured them.

3-4 years ago a slat kit was $4K from Backcountry Supercubs. No idea what they are these days. Carbon Concepts sells a CF slat kit now, too.
 
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I’d sure like to try my Cub on floats, but there’s a lot more to it than just slats. I’d also like to try a mostly stock Cub with the AOI increased a few degrees on floats. I think that would be better than slats on an otherwise standard wing.
 
Oli, have you ever pinned your slats open to determine how much a non-movable slat impacts your cruise speeds?
 
Colorado-Cub said:
Oli, have you ever pinned your slats open to determine how much a non-movable slat impacts your cruise speeds?
Click to expand...

No. Not in flight yet..

But I tough to pinned them close to see if it fly faster. But after trying to close them by hand in strong wind, I was afraid the mounting brackets would break with only one pin per wing. A guy in Canada used to fly with 1 pin per wing without any issues...
 
I pinned my slats shut in flight but I used bolts at each bracket. Thought it gave me about 2-3 mph. Not enough difference for an hour flight. Like the safety factor more than that.
 
gpepperd said:
I pinned my slats shut in flight but I used bolts at each bracket. Thought it gave me about 2-3 mph. Not enough difference for an hour flight. Like the safety factor more than that.
Click to expand...

That is really interesting. I always assumed that in normal low AoA flight the slats were essentially pinned against the top of the wing (closed position) by the relative wind. If you saw an improvement by pinning closed, something else is going on there.

I can see how a slat pinned open would lead to a decrease in cruise speeds, but not the inverse. Have you ever noticed your slats fluttering at the close-stop a bit during cruise? (which might explain how pinning them closed would lead to a speed increase?)
 
Never noticed any kind of flutter.

My slats fully close only when diving at high speed or momentary close in bumpy air, 2 things I try to avoid...


They are about at 1 inch to be closed when flying at cruise speed.
 
In 100 mph cruise my slats are partially open. Not a lot, but I can see light from under the slat trailing edges. .
 
Olibuilt said:
Never noticed any kind of flutter.

My slats fully close only when diving at high speed or momentary close in bumpy air, 2 things I try to avoid...


They are about at 1 inch to be closed when flying at cruise speed.
Click to expand...

No kidding? I had no idea.

I watched the lower edge of a slat from the backseat of an SQ2 from the lower 48 all the way to AK, but couldn't tell from my angle if the darn thing was floating or not. Super helpful info!
 
Huh. I would estimate mine open up to 1/4”. Probably less than that. But my Cub also cruises with the tail higher than most. I’d think flight attitude would matter. Location of the slats relative to wing LE, too.
 
Definitely position sensitive, the instructions I had were less than vague as to the correct position.

"You will also see that each hanger fits over the leading edge skin and rest best in a certain attitude. When drilling each hanger make sure each one is rotated into the same attitude."
 
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