Easymax vertical stabilizer breaks on every landing

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  • #35074
    sebastian.popp
    Participant

    Hello together,
    I built an Easymax and it’s flying well but on every landing no matter how soft it is the vertical stabilizer breaks between the end of the carbon tube and the start of the horizontal stabilizers. The geometry of the innner tube doesn’t allow an insertion of the carbon tube beyond this point.

    Any ideas from other Easymax pilots? I’m flying on normal grass fields, not perfect short 5cm airfield grass but I think it should withstand that.

    #35506
    Bernd1000
    Participant

    Post a pic of the structure of stabilizer or the stl file.

    #36020
    sebastian.popp
    Participant

    Sorry for the late answer, I was on holiday.

    I attached the section cut using Meshmixer. As you can see, there is no connecting structure between the vertical tube where the carbon pipe is inserted and the outer shell where the loads are introduced. So I added ribs, see the screenshot with the green arrow. There are 4 of them around the tube, forming an “X” when lokked from back to front. And they continue between the end of the carbon pipe and the first ~1cm of the horizontal stabilizer, to minimize the force peake in this area.

    The part is printed, the next days will show if it’s enough.

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    #53959
    sebastian.popp
    Participant

    I guess not many people are flying an Easymax in the “wild” (=grass), I would expect that topic to be much more poplar otherwise?
    The modified vertical stabilizer worked much better, but broke again today during landing. Again sraight at the small gap between the carbon pipe and the horizontal stabilizers.

    I spent the evening redesigning the pipe section, so it overlaps 1cm or so with the hor. stabilizers. This should finaly solve the problem.

    #55507
    mi_go
    Participant

    Did you solve this? I have broken my tail on soft landings as well. If you have the redesigned part that would be awesome!

    Mike

    #56467
    sebastian.popp
    Participant

    Sorry for late answer, it’s a shame the forum doesn’t support mail notification.. Hope you still read this nevertheless.
    The latest design I mentioned above was finished when the winter was comming, so it doesn’t have a lot of flights on it. But the single digit landing count is promising, no broken tail so far.
    I have no idea how we can share it legaly, as nobody from 3DLab seems to be reading inside here maybe I will mail them when it has a proven strength next spring.

    Maybe also helpful: I had a very hard time landing the Easymax where I wanted it to come down as it glides quite good and I don’t like turns in <2m height. I solved that by switching my throttle stick to air brake movement when I flick a switch to landing mode. Full air brakes equals ailerons up all the way the wires allow without coliding with the wing. Be aware you have to 0 the differencial movement, so the airlerons don’t move even more up of you use them for turns or it will brake the linkage or the wing!

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