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  1. #1

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    AT-6 Does Cartwheel - Damage is Light

    With no headwind down the runway, I let it get too slow, it dropped a wing almost 90 degrees catching the ground and doing an almost perfect cartwheel catching the right wing tip, over on the spinner, and then the left wing tip to end up on its feet facing down the runway.

    It is a twelve pound plane and the fueslage didn't get a mark on it other than a little dirt on the very end of the homemade solid aluminum prop nut. Yep... not a scratch to cowl, canopy or tail plane. Each wing tip scuffed slightly with seemingly perhaps a crack or two in wing tip area. The brunt of the force was dissipated by the wing tube bending back perhaps ten degrees where the left wing joins the center section. That caused the trailing edge of the center section of the wing to compress.

    Horizon has the wing tube available but are out of stock on the center section and the repair doesn't look too difficult. Now have the broken stuff removed and ready to begin repair.
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  2. #2

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    RE: AT-6 Does Cartwheel - Damage is Light

    Not to be negative, but there is more "hidden damage" many glue joints are weakened/broken and other wood has splits in the grain.
    Not a huge problem in smaller designs, but feel around for other soft or mushy spots. Do a static wing pressure test before flying.
    Check the firewall with the cowl off, good chance it has a fracture, that may turn into a major problem later.


  3. #3
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    RE: AT-6 Does Cartwheel - Damage is Light

    On mine, the firewall loosened up in midflight. I had the same model, I put the E-Flite retracts on it. I would definitely very carefully examine it. It only has 2 pieces of wood bracing it, on the inside, left and right side. The wood had split on one side, and the glue joint let go on the other side with all the vibration. It had been an excellent flyer.
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    http://www.tailhook.org/AVSLANG.htm
    Sign over Ready Room Door: \"Complacency Kills\" - Thimk

  4. #4

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    RE: AT-6 Does Cartwheel - Damage is Light

    Thanks for the comments.

    Nitro Wing... I agree that there could be unseen damage and have looked it over carefully. Have not opened the wing tips yet so don't know exactly what will be found there. I know there is a balsa split of an inch or so in the cap sheeting near one wing tip but beyond that I don't know. Will check them carefully. The wing tube in the damaged center section seems to remain glued well to the ribs.

    Bingo Field... The cowl did get pulled to inspect the firewall and all looks ok from both within and without. When constructing, it got triangle stock as well as fiberglass cloth reinforcing both inside and outside. The tail surfaces though having no marks were given some stress and showed no looseness. One thing not done yet is to exercise the servos though all their mounts were inspected and remain solid.

    Hinges were looked at and are ok... CA hinges are not used here as I don't trust them on 1.20 size planes.

    It was an unusual ground mishap as I've never before seen such a cartwheel. Usually the down wing takes a very hard crunch and buckles but in this case that wing tip caught and summer saulted the plane in a cartwheel and it was the opposite wing that ended up taking the brunt of it and dissipating momentum via the bent wing tube and buckled aft center section. The wing that hit first, the tube remains perfectly straight. Had it not, it would have required cutting off to pull out of the fairly tight center section tube.

    Mine does not have retracts as our field is generally too rough for successful retract installations.

    Might have time today to start putting it back together.

  5. #5

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    RE: AT-6 Does Cartwheel - Damage is Light

    The broken rib and rear spar have been repaired. Needed is to examine if I've got sheeting that will work. Mixing metric/fraction sized balsa is sometimes a pain. A few hours are needed for drying as I use titebond mostly.

    Note that a couple of temporary positioning stringers are tacked in place to hold the rib end in place while gluing.



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  6. #6
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    RE: AT-6 Does Cartwheel - Damage is Light

    I just had to use sandpaper to fix the sheeting issue. I sanded it before I cut it to fit. I had to open up the area in the wings where the fastener that holds the wing tube went through because it the hole hadn't been put in the right place, and resheet that. Not even close. I ended up cutting about a 2 inch square out to give me plenty of room to see, and when I was finished, after I put the patch on, I made a pseudo access panel out of it by outlining the patch with a .5 mm artists ink pen marker. It's what I used to put panel lines on my P-47 with and it didn't look bad.
    I could fly this thing off the ground quite slowly, and it really looked good when you put the gear up while still over the runway before you bank and turn. I had the zenoa g-26 in mine, way more power than it needed. I really believe you could fly this with a SuperTigre 91, you need the weight in the front to balance it.
    The biggest reason I wouldn't buy another one is the super soft balsa they use, and the unknown wood used for ply. I found any work on it was difficult due to the brittle nature of it, and very little stress would cause it to split. This plane was fairly light, and once assembled, it did fly well until the firewall detached.
    http://www.tailhook.org/AVSLANG.htm
    Sign over Ready Room Door: \"Complacency Kills\" - Thimk

  7. #7

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    RE: AT-6 Does Cartwheel - Damage is Light

    Yep... the wood is very soft. And... it is a good flier.

    My challenge is to remember not to fly the other planes like the Ultra Stick Lite 1.20 primary plane.

  8. #8
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    RE: AT-6 Does Cartwheel - Damage is Light

    I hope the repairs do well for you, mine was just a few splintered pieces of wood held together with strips of ultracote once the trees got done sifting it from the sky. It even bent up the retracts at the mounts. I was somewhat heartbroken, the full scale AT-6's fly above my house, and field, during the early part of July just before the Geneseo airshow. I look forward to that every year, and it is in the best time of year to fly here.
    http://www.tailhook.org/AVSLANG.htm
    Sign over Ready Room Door: \"Complacency Kills\" - Thimk

  9. #9

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    RE: AT-6 Does Cartwheel - Damage is Light

    Tree crashes are often fatal. Our field lies on an old landfill and beyond the landfill area are trees and crashing there almost always means into a tree with many times the plane becoming lodged aloft. Fortunately, we are able to cut the tree to retrieve the plane but that often means more damage.

    My repairs are relatively minor so I'm sure the AT-6 will fly again and hopefully I'll be a bit more careful to keep the air speed up when landing.

    We've a small city owned airport near that is managed by a Viet Nam Era combat pilot who promoted yearly fly ins that included a good many interesting planes. Unfortunately, the city fathers always concerned about PTA, slammed the door on him requiring event insurance, which shut the events down. There were generally 3-4 AT-6s as he owns one of them. The last one they had featured a P-40, which was parked front and center.

    After a while, they tugged it over and refueled it and then parked it down near the taxi way where it sat for a while. Then, I noted a doddering old gent meander out toward the plane and it became obvious quickly he was doing a preflight. Shortly thereafter the PA announcer gave the rundown on the plane and its pilot who had brought the plane in from the Dallas - Ft. Worth area and was a veteran P-40 Flying Tiger in China flying for Chenault. This was two years ago in 2009 and the FT served in 41-42 so that would have been 67 years previous. If he was a young twenty year old pilot then he would have been 87 years old. At any rate, he climbed unassisted into the plane, fired her up and took off bringing it back around and down and low over the runway a few times with a victory roll after the last pass before turning it west towards DFW.

    It was a beautiful thing to see and left a feeling of awe and wonder and knowing that I'd likely never see another Flying Tiger handle a P-40 again.... maybe not ever see another P-40 fly.

  10. #10

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    RE: AT-6 Does Cartwheel - Damage is Light

    Not a lot but some progress in the repair. It has been my experience that if a little can be made at a time, the project does keep going and gets done, compared to what is sometimes seen where a project lies dormant for many years. I've had that happen, probably most of us have.

    As can be seen in the pics, the broken rib and spar have been repaired. Now the sheeting is on the upper side of the wing section and underneath the books drying is the fitted sheeting section for the underside.

    I haven't got into the wing tips yet as I was waiting to finish the center section and get it mounted back to the plane so that the plane can return to its hanger in the garage. It hangs from the ceiling on the wing tube and I need it out of the cradle and back in storage as my work space is limited with the cradle on one of my benches.

    In the middle of this, the tail wheel broke off (music wire snapped when the wheel hit a rock) on the Ultra Stick Lite and bench space was needed for that. The repair was finished in a couple of hours and made much easier because the last time it happened, a single hinge wire was installed making it very easy to pull the rudder. A friend at the field suggested a heavier piece of music wire, but I'm happy the 3/32 wire has failed twice now instead of ripping out some structure. The stick has a lot of hours on it.

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  11. #11

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    RE: AT-6 Does Cartwheel - Damage is Light

    Wing sheeting finished.
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  12. #12

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    RE: AT-6 Does Cartwheel - Damage is Light

    Wing tip damage.
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  13. #13

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    RE: AT-6 Does Cartwheel - Damage is Light

    I got a heads up over on the Seagull AT-6 thread not to move the holes for the wing screws/bolts for the wing tube inboard because that is where the support is built into the wing. Unfortunately the tube I bought from Lowes was 36" and needed was 37". The path I chose was to braze a one inch piece on one end.

    The ends were trued and chamfered in the lathe and held together there during the brazing and then the excess weld turned off. I've had very good luck with aluminum brazing being quite strong and have very little concern about the strength.

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  14. #14

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    RE: AT-6 Does Cartwheel - Damage is Light

    Both wing tips turned out to be simple repairs to the wood, just a matter of prying the broken pieces back into alignment and hitting them with CA. Some lightfill and sanding will prep for recovering of just those areas exposed. I'm not a perfectionist and a repair seam is of no issue to me.

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  15. #15

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    RE: AT-6 Does Cartwheel - Damage is Light

    Concluding the documentation of the repair. Thanks for the heads up about the need to stay with a full length wing tube and to be cautious to look for other damage.

    Repairs come with RC modeling and even seem to offer a segment of the hobby enjoyment. Personally I enjoy the repair documentations and watching a broken bird repaired to take flight again.

    Among other things, a crash is a learning experience. While each has a way of requiring innovation in the repair, it requires retrospect of why it happened. In my case it was the timeless dictum of getting too slow and stalling. One of my repair efforts will be to trim up the ailerons a bit when reducing power to reduce the tip stall character slightly but having gone through the process of a repair in exchange for the neglect... lessons learned the hard way seem to stick more indelibly in the mind.

    May your repairs be minor and thanks for following.

  16. #16
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    RE: AT-6 Does Cartwheel - Damage is Light

    I can certainly agree about the lessons learned the hard way[8D]
    http://www.tailhook.org/AVSLANG.htm
    Sign over Ready Room Door: \"Complacency Kills\" - Thimk

  17. #17

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    RE: AT-6 Does Cartwheel - Damage is Light

    I ran into one other issue with the repair. The stress of the cartwheel elongated slightly the holes in the outer wing sections where the bolts secure the wing sections to the wing tube. It appears that movement was limited but nevertheless enough to cause more end play than desired when bolting the wing ends on.

    My thinking is to install a plastic sleeve into the hole and then flush cutting to the wing surface using masking tape to hold the multi-tool cutter above the surface. This will require clearing out the section through the cardboard tube. That should be possible by one of two methods, filing saw teeth on the end of a tube or heating the end of the tube to melt the section away. My thinking is the saw method would be better.

    Otherwise the filling and sanding are complete and ready for covering, which is planned as the final step after affixing the outer wing sections and drilling holes in new tube.


  18. #18

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    RE: AT-6 Does Cartwheel - Damage is Light

    Well, that was easy. The blue nyrod was a tight fit going through and was left a little long on each side so that CA didn't go into it when gluing. A few drops on each end secured it. Then tape around the rod, and cut off with the multi-tool.

    It took only a few minutes with a triangle file to form a saw on the end of the old tube and a dozen or so turns in each hole to cut the plastic insert. Don't force it, just enough pressure to let it saw. Perfect... simply as pie and now tight holes with no wobble as well as providing a super drill guide for the holes in the wing tube.

    I think heat on the tube would work well too... but the saw method was simple.
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  19. #19

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    RE: AT-6 Does Cartwheel - Damage is Light

    I put blind nut in top of wing instead of running the bolt through with nuts. Many flights, no problems, less parts to assemble. Just an ides for next time. Happy New Year, Dave

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    RE: AT-6 Does Cartwheel - Damage is Light

    Good plan.

    I also drilled and tapped a hole in the center of the tube for a screw from the top side of the center wing section. This keep the tube in place instead of struggling to line up the tube holes for the outer wing sections.

  21. #21

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    RE: AT-6 Does Cartwheel - Damage is Light

    Atother  good  idea !  Thats what reading these is all about. Ideas from fellow builders / flyers. Happy New Year, Dave


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