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Thread: PA18A Differences?

  1. #1

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    PA18A Differences?

    Does 'A' stand for Agricultural? Excuse my ignorance but I couldn't find any info on the modifications that were made to the PA18 to make it an 'A'.
    Could anyone detail the differences between the PA18 and the 'A'?

  2. #2
    Torch's Avatar
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    This is taken from a model aircraft site on the web.

    The PA-18A was designed initially as a specialized agricultural duster/sprayer airplane introduced in 1952; it incorporated as standard a chemical hopper and spray/dusting gear, but was easily convertible for general-purpose use, and when production of the airplane ended a total of 2,650 Super Cubs had been built. The PA-18-150 Super Cub was powered by a 150-hp Avco Lycoming 0-320 flat-four piston engine, giving the airplane a maximum speed of 130 mph, service ceiling of 19,000 feet, and a range with maximum payload of 460 miles.

    The TORCH is a PA-18/A.


    Torch

  3. #3

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    Thanks for the info. BTW Torch is a nice looking SC
    Now can anyone describe diffferences to the fuse & or wings etc. that were implemented?
    The reason for my interest is that some of these planes were widened and fitted with side by side seating by someone and I'd like to get a handle on what was required to do it. If I can get some pictures I'll try to post them.

  4. #4

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    nocubyet

    See http://www.supercub.org/phpBB2/viewt...?p=30536#30536

    I've never seen or heard of one being widened to allow side by side seating nor am I aware of any STC that would allow that, but... anything is possible.

  5. #5

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    Thanks for the info.
    Apparently the fuses were modified for training. Approx 6 planes were done and all for Aero Clubs circa 1960. In those days I don't know if the STC rules were enforced all that tightly here but the job may well have been done by the airline workshops or even military. I will attempt to find out some more and post what I can find. I take it from your surprise none of these mods showed up in the US? We have managed to get away with lots of aircraft modifications in this country that I'm sure would not have been allowed elsewhere!

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    FlipFlop's Avatar
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    Quote Originally Posted by NoCubYet
    Thanks for the info.
    Apparently the fuses were modified for training. Approx 6 planes were done and all for Aero Clubs circa 1960. In those days I don't know if the STC rules were enforced all that tightly here but the job may well have been done by the airline workshops or even military. I will attempt to find out some more and post what I can find. I take it from your surprise none of these mods showed up in the US? We have managed to get away with lots of aircraft modifications in this country that I'm sure would not have been allowed elsewhere!
    What country?...
    ô¿ô Ladies And Gentlemen, Cuby (et al) Has Left The Hangar...

  7. #7
    jk's Avatar
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    Torch forgot to mention that on most "A" models, they were built with heavy longerons and certified from Piper at special purpose Gross load of 1777 lbs.

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    cubdrvr's Avatar
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    I thought it was 2050#.
    "Sometimes a Cigar is just a Cigar"

  9. #9
    SuperCub MD's Avatar
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    2070#

    Torch, did your's leave the factory with floats? It could be a rare PA18AS?

    dg's explaination hit the big stuff, plus the rudder deflection is increased to 25 degrees.

    I think I remember that there is a STC for widening a PA18 to 4 seats on the books, don't remember who has it.
    Thanks jayb thanked for this post

  10. #10
    55-PA18A's Avatar
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    The original log book for my 1955 "A" model shows 1,950 pounds for gross weight.

    More questions:
    Is the gross weight difference between the Ag model and the standard PA-18 (at 1,750 pounds) because the 18A is (was ?) under a different category (Utility or Restricted?), and the standard 18 under Normal category? If so, why is there a difference? Anyone out there still operating an 18A under the higher gross weight category? (There's a 1959 entry in my log book stating "Aircraft flown with 850# in hopper and found to operate satisfactorily and be safely controllable" )

    Does anyone know the story behind the 18A originally having the "flat" back?

    "55"

  11. #11

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    I believe the higher gross weight was applicable only when the airplane was operated in the restricted category. The flat back is due to the shape of the hatch frame and cover and the matching turtle deck. If you view this photo at it largest size and look closely you can see the A model superstructure and turtle deck. http://www.supercub.org/gallery/view...album03&id=aaq
    Likes dstr59 liked this post

  12. #12
    CubCouper's Avatar
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    I don't know much of the story on the flat back cubs but there is a bit of explanation and footage on the DVD sold on this site:

    http://www.hvpvideo.com/NEW%20PRODUCTS.htm

    The documentors suggested that the flat back was to give the guy dumping the chems into the hopper a place to stand, thereby speeding up the loading process. Their footage obviously proves that it was used that way.

  13. #13
    mvivion's Avatar
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    The higher gross weight for the A model was based on operation in the restricted category.

    If you want to go there, you need to read carefully the "restrictions" and understand the certification standards in that category for the Cub, which basically put the limit load factor very low. In other words, at that weight, the factory said all bets are off regarding structural integrity.

    This is pretty common in the restricted category.

    Wipair sells an STC to up the gross weight of your cub to 2000. It's a lot better deal, even though it costs something.

    I believe that A model airplanes also had no rear controls, as in the torque tube was very different. The top of the airplane was flat to accomodate the top hatch, to facilitate loading the hopper. It was hinged at the front.

    As to float certification, very few Cubs were actually built as PA-18 S models, which was the seaplane version, but for all practical purposes, they are virtually all convertable easily to floats, and the FAA has been willing to approve them pretty universally.

    I suspect that almost all A's have been conformed to the basic PA-18 configuration by now, for practical purposes.

    MTV

  14. #14
    Torch's Avatar
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    Quote Originally Posted by SuperCub MD
    2070#

    Torch, did your's leave the factory with floats? It could be a rare PA18AS?

    dg's explaination hit the big stuff, plus the rudder deflection is increased to 25 degrees.

    I think I remember that there is a STC for widening a PA18 to 4 seats on the books, don't remember who has it.
    Yes it did. I still have all the paperwork. I will have to look closer for the PA-18AS. I just went through all the log books. Torch is a PA-18AS. Came from the factory on floats. Still have the paperwork. How rare is the aircraft?

    Torch/Don

  15. #15
    SuperCub MD's Avatar
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    Torch, I just had a feeling....

    "A" models did NOT just mean sprayers. It had more to do with the fuselage structure. The A model could also be had in a cargo configuration. This meant it would have a fully removeable rear seat back and bottom, rear controls, and full length floor boards with cargo straps. This means that when the rear seat was removed there was a baggage area from the back of the front seat all the way to the back of the cabin with the floorboards laying down on the lower longerons. These A model cargo Cubs make use of the area below the rear seat and standard baggage area that the standard Cub wastes.

    If the Torch is a true AS, the original purchaser must have been looking for a true hard working float plane, and knew what to buy. I don't know how truely rare it is, but I have no doubt that it is a great airplane.

    Just so there is no confusion, when these planes are operated in the standard category, they gross at 1750 like the others, the 2070 is restricted cat only.

  16. #16

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    Some where around here I’ve got a picture of my uncles crop duster a 1956 pa18a it had flat back and no rear controls and yes the flat back was convenient (as could be for this style but a joke compared to Pawnee) I never remember weighing anything back in the day but I do remember him yelling at us if we loaded the hopper to much toward the back something about him having to lock his elbow to hold the stick forward till he got off the first few passes. (Wow those were crazy days). Corrosion was so bad after all the dry fertilizer we replaced almost every tube in that thing. Great plane he sold it in 1978 for $3500 I’ve regretted that day ever since. But, that’s why I got into aviation.
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  17. #17

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    Quick question involving the PA-18A, is it hard to convert it to the classic turtledeck? Looks like a few tubes removed and a few added. Ha anyone here done that? Cheers

  18. #18
    phdigger123's Avatar
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    Quote Originally Posted by mstocker1983 View Post
    Quick question involving the PA-18A, is it hard to convert it to the classic turtledeck? Looks like a few tubes removed and a few added. Ha anyone here done that? Cheers
    I guess I might be partial to the A models, but why would you change it to look like a regular Super Cub? The A models draw a little bit more attention, I understand they are slightly faster, the flat back look is becoming harder to find due to fuselage replacements, and they look better imho.

  19. #19

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    Thank you for the input. I am just throwing around ideals. The plane has some pretty serious fuselage issues and it might be worth it to build a new fuselage. This thing has seen some ****. Anyone have any drawings for the PA-18A? It seems like all the other drawings are pretty easy to get. The A is another story. Cheers

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