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Thread: Super 20 Dakota Cub Slotted Wing Pacer

  1. #1
    Steve Pierce's Avatar
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    Super 20 Dakota Cub Slotted Wing Pacer

    I have recently been playing with Dakota Cub's new slotted wing Pacer. This is an experimental research and development project to see if this is a viable modification to pursue. The wing has almost the same wingspan as a stock winged Pacer but squared off and with the wing tips it is actually 2" longer. The ailerons were moved outboard to the tip and lengthened to 74" vs. 72" and the flaps were lengthened from 52" to 74". The aileron moved out to the tip gives the Pacer the much needed aileron authority in a crosswind and with 42% more flap you can really slow her down without a terrible sink rate. The leading edge slot that Piper originally used on the L14 and that is certified via STC on the Super Cub and on the Type Certified Super 18 is really amazing to me in several flight regimes.



    Take-off is very quick using one notch of flaps, then pulling full flaps when she is ready to fly and once in the air dumping them and climbing out at a very high angle of attack. This was kind of un-nerving at first until I went up high and flew the airplane at these attitudes. Pulling the power of at nose high attitudes simply made the nose come level and the airplane descended about 500 fpm in a level attitude with full control. I left the right rudder in that I was using to keep her straight when I had full power and didn't understand at first why I was rotating to the right in a flat attitude. I finally realized it and let off the rudder pedal and the nose stayed straight. The high angle of attack and climb really shines for getting over an obstacle in short order. With some 17 kt. winds last weekend I climbed to 1000' in about a 1000' of runway and actually ended up flying backwards. It was pretty amazing to me.



    My landings have been as short or shorter than my landings were in Bill Tracy's 39Y the previous day however I had 10 kts. more wind the day I flew the Super 20. I am not flying a real steep approach but keeping her pretty flat and allowing my rate of decent to put air through the slot. A burst of power works real well right before touch down to arrest the rate of decent and land really short. I tried this with the Sensenich 7458 prop but it did not work as well as the 8243 Borer I borrowed from Bill. The Sensenich gives 115-120 mph cruise and respectable short field take-offs the Borer gives 102-105 mph cruise and some really short field take-offs and landings. Will be testing with an 8244 next week to see what kind of short field and cruise I get.

    I have really had a lot of fun with this project and though the Pacer is not near as fun to fly as a Super Cub it does have an 800 lb or more useful load and a decent cruise speed with lots of room for people and stuff and is a lot more in my budget than a Super Cub right now. I have uploaded several videos to YouTube http://www.youtube.com/my_videos?feature=mhw4 and there is a long discussion with some good data from Dakota Cub on the history and performance of the slot as well as some comparison between the slot and VGs on http://www.shortwingpipers.org/forum...Super-20-Flies if anyone wants to know more about the Super 20. Cathy and I will continue to do some performance testing here and will have the airplane at Sun & Fun in a few weeks as well.

    Steve Pierce

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  2. #2
    fabricfan's Avatar
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    Awesome Plane

    That is a seriously handsome plane Steve. I just read "In the Shadow of Eagles" by Rudy Billberg and he had a 'flying backwards' story that I found fascinating, so I bet it was a unique experience. Cool deal.

  3. #3
    Iflylower's Avatar
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    Super cool

    Pacer Ron here in Memphis had lunch today with your dad and was excited as a school boy about the plane and new wing and told me all about it. He was only a little disappointed when I told him I knew about it. He can't wait to see it.

    I'm sure Ron will hunt you down at Sun N Fun. I'm looking forward to seeing you guys and the plane too.

    Sounds like a hot performer. Needs Bushwheels maybe???!! I know where there are some....

  4. #4
    FdxLou's Avatar
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    Cal

    What days will you be at SnF?

    Lou

  5. #5
    Bugs66's Avatar
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    Better link to Steve's YouTube videos:
    http://www.youtube.com/user/stevepierce

  6. #6
    Iflylower's Avatar
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    12 and 13.

    It's a short one.

    Of course I'm hitch-hiking with my 195 buddy. His baby is due on the 25th and he was only given a 2 day hall pass. I don't care, cause I'll be back to the project faster. Gotta keep pushing.

    See you there? I'll look for you if you're around.

    Oh, and pacers are cool. I can't wait to see Pierces fly. I think it's my favorite pacer so far. It looks really, really good on 29's.

  7. #7

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    One question...

    How much do the slotted wings slow your cruise speed?

    Mike

  8. #8
    Gunny's Avatar
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    Re: One question...

    Quote Originally Posted by CptKelly
    How much do the slotted wings slow your cruise speed? Mike
    The slotted wing does not slow or improve your cruise at all.
    "You are the Gray Rider who would not make peace with the Blue Coats, you may go in Peace." - Ten Bears

    Gunny

  9. #9
    Steve Pierce's Avatar
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    The flight test engineer on the Super 18 told me you might loose 1 mph. I can't tell a difference in cruise between this Pacer and others I have flown but I do know it gets in and out better than any Pacer I have ever flown.
    Steve Pierce

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    Will Rogers

  10. #10

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    I think the cruise speed loss in question comes from the "extended" part of the extended slotted wing and not the slot. More leading edge equals more drag. Not much affect a short wing.

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    Nice looking plane. Did you achive that cruise speed with 26" goodyear tires?

    Cub_Driver

  12. #12
    Steve Pierce's Avatar
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    Quote Originally Posted by cub_driver
    Nice looking plane. Did you achive that cruise speed with 26" goodyear tires?

    Cub_Driver
    Yes. Supposed to get the 8244 Borer today so it will be interesting to see.

    Groundloop, I didn't think of that. Makes sense.
    Steve Pierce

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  13. #13
    skywagon8a's Avatar
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    Quote Originally Posted by ground loop
    I think the cruise speed loss in question comes from the "extended" part of the extended slotted wing and not the slot. More leading edge equals more drag. Not much affect a short wing.
    Yes but--- increased aspect ratio = less induced drag and better low speed performance. IE: gliders with long (high aspect ratio) skinny wings = excellent low speed performance. The slot shines at high angles of attack. A well designed slat/slot should disappear aerodynamically at cruise speeds.
    N1PA

  14. #14
    Gunny's Avatar
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    Quote Originally Posted by ground loop
    I think the cruise speed loss in question comes from the "extended" part of the extended slotted wing and not the slot. More leading edge equals more drag. Not much affect a short wing.
    But that part of the wing is now flying on the squared off wing - i.e. creating lift where the stock rounded wing tip was just looking good - now the airfoil extends all the way to the tip cap as opposed to ending where the bow tip starts on the stock wing. That's about 1.5-2.0 feet more of airfoil and lift.
    "You are the Gray Rider who would not make peace with the Blue Coats, you may go in Peace." - Ten Bears

    Gunny

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    I buy the 1 mph reduction - there has to be some disturbance due to the slot. This one sounds like a winner - what I want to know is why hasn't Dakota also included the Clipper style controls in the cockpit? Heel brakes would be a safety thing, and that stick is so much more comfortable than a steering wheel. Opinion, of course.

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    If lift is the more important factor than drag for airspeed, then a PA-18 should be much faster than a 12 or 14. With the 18 it isn't ony about leading edge for drag it also about the angle of incidence plowing air, so more surface area is also more drag.

    I lost about 1/2 -1 mph with the extended wing and gained it back and then some when I switched from Edo's to Aerocets.

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    super 20

    what a great looking aircraft. I need a set of those wings for my clipper.
    life is not a dress rehearsal do it up right the first time

  18. #18
    Bushwhacker Air's Avatar
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    I learned to fly in a Tri-Pacer - don't ever remember the ground falling away that fast!!! Great vids - amazing -20!

  19. #19

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    Did you post the stall speeds or did I miss it?

    Cub_Driver

  20. #20
    Steve Pierce's Avatar
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    It won't stall so to speak. I flew it at 6 mph going backwards but the wind was really blowing. When the tail starts shaking and back pressure is retained the nose will fall to a level attitude and she will fall 500 fpm with full control. Just got an 8244 prop and plan to do some more testing. Wish the wind would let up a bit to make testing a little easier.
    Steve Pierce

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    Is this all being done with a 150, 160, or 180hp?

  22. #22
    Steve Pierce's Avatar
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    160 hp O-320 narrow deck.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
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    Keep us posted on your test results. I don't know why but I have always liked those tuff ugly little pacers. Are you flying with stock tail feathers?

  24. #24

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    I see a possible weakness of the slotted Pacer is that the aileron is not far enough out to be effective at the slow speeds when the slot is fully engaged. Crosswind take-offs may be an issue.

  25. #25
    Steve Pierce's Avatar
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    Running PA18 elevators and stabilizers.

    Ailerons are actually great on this Pacer. 2" longer and moved all the way out to the tip to make up for the flap is 74" long vs. the 52" stock flap. Flying in 24 kt gusting to 30 crosswinds and I had full control. A stock Pacer I would have piled up because of the lack of aileron control with the short aileron especially when people add 2 more rib bays of wing outboard of the end of the aileron.
    Steve Pierce

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    Will Rogers

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    Steve,

    Thanks for the resposnse. I was thinking that a cub extended wing has a aileron that is about 100 inches starting about 192 inches out from the fuselage and the pacer you have has a 72 inch aileron starting about 144 inches from the fuselage. It gives the cub about 40 inches of aileron WAY out there where it is more effective and 30 more overall inches of aileron.

    When I spoke to a guide who had the non-extended slotted wing on a cub he said the circumstance I previously mentioned is where he got himself in trouble. I was thinking that your pacer may have the same issues. Could you explain and help me understand how this pacer is overcoming this apparent defecit?

  27. #27
    Steve Pierce's Avatar
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    Not sure of the defect other than having a shorter wing at 154". Much better than a stock Pacer for sure. There is a PDF file here with both stock and slotted Pacer wings and dimensions. http://www.shortwingpipers.org/forum...Super-20-Flies It still doesn't have near the wing area of a Super Cub but more than the stock Pacer. There is also a lot more dihedral in the Pacer wing than a SC. Not sure what that does to the whole thing.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

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