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  1. #1
    Nodd's Avatar
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    Tip-stall prone Cub

    I'd been flying this Piper Cub (from Nitroplanes) for eight months now. She entered a spin around 60 feet up, this was the result...



    She was a nice looking plane, lots of scale detail, fair quality parts. She always felt a little on the heavy side though, flew like she had a moderate wing-loading, not very Cub like IMO. She also had a real nasty tendency to tip stall. I played around with the CG, that didn't help. Looking at the wings, there appeared to be zero washout built into the wingtips. That combined with the weight & a short coupled tail meant she was a real handful if stalled. Probably didn't help that I botched a stall turn (hammer head) at around 60', sent her into a nasty spin. As expected at that altitude there wasn't enough room to recover. Also didn't help that I nailed the throttle in hopes of powering out... CRUNCH... right into the dirt.

    Oh well. I probably could repair her but I think I'm going to lay her to rest. If she was a nicer flying plane maybe I'd break out the glue but I think I'll salvage the parts & use them in another project.

    ...and another one bites the dust

  2. #2
    Live Wire's Avatar
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    RE: Tip-stall prone Cub

    Rebuild it , it will fly better than it ever has You may find out it was just how the engine was mounted, angle of attack. my SIG was worse than that and I flew it straight in (Dumb Thumb) fly's great after rebild.
    Larry K
    Sig Brotherhood # 1 Sig Kadet Brotherhood # 4 WACO Brotherhood #34 Cub Brotherhood 14

  3. #3

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    RE: Tip-stall prone Cub

    Just build it up again.

    Never try to stop a spin with more power. Use the rudder.
    If the plane spins to the right use left rudder to stop the spin, if it spins to the left use right rudder. After the spin stops you can apply a bit of power and pull out.

    regards
    Knut I. Skattebo

  4. #4

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    RE: Tip-stall prone Cub

    Your Cub is a clipped wing version and more aerobatic than a standard cub. You are right however in that many Cubs will tip stall and some easily. I've both a Goldberg Anniversary Cub and a World Models. The builder of the Goldberg added washout to the wing and it is very forgiving, while the World Models is not so much. After a tip stall and rebuild of the World Models, effort was made to tame it a bit with a few changes.

    Ailerons were given some differential and up trim at lower throttle to simulate washout. Some rudder mix was added. The up trim works fairly well with barn door ailerons and would work on your model or you could try to introduce some washout by twisting the wings and shrinking the wrinkles.

  5. #5
    Nodd's Avatar
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    RE: Tip-stall prone Cub

    From what I can tell, mine was not a clipped wing Cub. Its wing was 155% of its fuselage length. After taking measurements from various clipped wing Cubs they seem to have wings ranging from 125-147% fuselage length. Mine cirtainly wasn't very aerobatic either.

    That's good advice about using the rudder to stop a spin, I'll have to practice that. Truth be told, I doubt there was much of anything I could have done to save her though... just too low.

    I would have loved to twist in some washout but not sure if that's possible with a foam wing. I assume applying heat, much the way you do with a built up covered wing, might work? Sounds a bit iffy for foam though.

    I really like the throttle to aileron mixing idea (ailerons move up a little at low throttle), that's brilliant! I'll have to give that a try on my Spacewalker & see how she handles.

    Anyway I have no plans to rebuild her, already tossed the airframe in the bin (although I did keep the electronics & the wing). I think my next Cub will be a nice built-up from Sig or Great Planes or if I'm going to do another foamie, the Fun Cub flies nice. Interestingly it looks like Nitroplanes may have discontinued the model I had. Not a big surprise there.

  6. #6

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    RE: Tip-stall prone Cub

    Yeah... no twisting a foam cored wing. I could be wrong about it being clipped... just looked that way in pic to me.

  7. #7

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    RE: Tip-stall prone Cub

    It is possible to twist a sheeted foam wing. But the method is not for the timid!

    You have to slice though the sheeting on the underside of the wing, on a diagonal direction, from the leading edge at the root to the trailing edge at the tip (this is the direction to add wash-out). Twist the amount and glue with lightweight glass cloth across the seam. Since this takes time, you need to jig up the wing to hold the twist in while the epoxy sets.
    - Supplementary insipid innocuous inane vacuous proclamation

  8. #8
    KitBuilder's Avatar
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    RE: Tip-stall prone Cub

    that looks clipped... short wing..
    Mike -
    I was born a pilot... 100 years to late.

  9. #9
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    RE: Tip-stall prone Cub

    that looks clipped... short wing.
    I have a GP 40 size cub I built thats worse than that and I'm going to fix her up.. go for it... wont take long.
    Mike -
    I was born a pilot... 100 years to late.

  10. #10
    Nodd's Avatar
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    RE: Tip-stall prone Cub

    As I posted earlier it was not a clipped wing Cub (measured & confirmed). As I also stated, the airframe was already tossed out, so no I'll not be fixing her up.

    At some point I'd like to get another Cub, its just one of those must have planes. How's the Great Planes Cub, flies nice?

  11. #11

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    RE: Tip-stall prone Cub

    It's a shame that it is too late for a rebuild.........I have rebuilt often and have a lot of fun flying a plane that has already been crashed....I become more bold and try to do things that I wouldn't try with a nice new shiny plane.....what the heck, it has already had its' day and if it crashes (not my fault..of course) no big deal.

  12. #12
    Nodd's Avatar
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    RE: Tip-stall prone Cub

    I have plenty of old beat up planes already *smile*. I know what you mean about carefree "old beater" flying.

    Yeah IMO the Cub was too far gone, the foam would have been an easy fix but the plastic cabin / wing support area was completely shattered, not an easy fix. If she'd been a better flying plane maybe I'd have taken the time to fix her. Better to move on & fly something nicer. I did keep the wings, might reuse those in some Frankenstein project down the road.

  13. #13
    Nodd's Avatar
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    RE: Tip-stall prone Cub

    All is not lost! I've decided to make a new plane from the remaining parts. You can read about that project here...

    Piper Cub Sailplane

  14. #14
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    RE: Tip-stall prone Cub

    Apologize.. didnt read the full post about not rebuilding..

    My GP Cub kit build was an easy build, flew excellent and nicely aerobatic. The kit is very sport scale so I added some scale "looking" landing gear and Jury struts to finish it off. Going to start the rebuild very soon. Covered in White solartexa and blue ultracote. Got a little carried away with the checks. Going with a wood prop whch will really set if off next time it handles that sweetly once I get the rebuilt maident out of the way.
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    Mike -
    I was born a pilot... 100 years to late.

  15. #15
    Nodd's Avatar
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    RE: Tip-stall prone Cub

    Oh yeah now that's a Cub. I can tell at a glance that thing is quality, puts my old foamy Cub to shame. I love what you did with the graphics. At some point I'll put another Cub together for sure, definitely liking the GP Cub.



    In the mean-time I've successfully built a goofy little sailplane from my old Cub's wings & tail. I'm quite pleased with that project...

    Cub Sailplane - Build Log

    Cub Sailplane - Flight Footage

  16. #16

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    RE: Tip-stall prone Cub

    Thanks for the link... to an enjoyable read of your fun with the surplus wings. Very well presented.

  17. #17

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    RE: Tip-stall prone Cub

    Why a cub ,real planes have the wing on the bottom......he he he


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