FRCFoamies SBACH 342 Advanced Profile Parkjet

Discussion in 'FRCFoamies Plans' started by F1wanabe, Sep 6, 2015.

  1. Sterling101

    Sterling101 Top Gun

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    Decided to give this a go with a view to it becoming an indoor plane over the winter. Might throw some basic undercarriage together for it too.

    Started this morning and finished this afternoon, just a bit too late to get out and fly though. It might not be the prettiest of builds but it'll do fine to play with anyway.
    It's now got some colour too provided by my good lady and her collection of Sharpies :) It's got black stripes on the underside of the wings and horizontal to aid with orientation.
    I raided the parts drawer and ended up with it running a Turnigy 2200kv motor turning an APC style 8x4 prop, Hobbywing Skywalker 20a ESC, some random clone Tower Hobby 9g servo's and powering it from an 850mah 2S nanotech battery. AUW is 365g so plenty light enough I think.
    Will see if I can get a maiden in tomorrow before the storms hit with high winds and snow but I won't be holding my breath...

    IMG_20181215_004626.jpg
     
    Last edited: Dec 14, 2018
  2. What???? That doesn't look like a 4 foot WS!!!!!
     
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  3. Sterling101

    Sterling101 Top Gun

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    Only a dinky one at 36" - still working on the plans for the next "slight" build at 96" :D
     
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  4. I was counting the floor tiles, usually 1' square. ;)
     
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  5. Sterling101

    Sterling101 Top Gun

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    They are indeed so it's a handy measure to make sure I've built it big enough :D

    Currently enjoying some lovely freezing rain and 15mph ave winds - hibernation is definitely a better option I think at the minute!
     
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  6. F1wanabe

    F1wanabe Administrator

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    Good luck with the maiden, Sterling! That does look like a nice size there. Love the Sbach. Learned how to really use the rudder on that one!
     
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  7. Sterling101

    Sterling101 Top Gun

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    Managed to jump out literally minutes before the light went tonight in totally still air and maiden the SBach.
    Flew right out of my hand no problem at all but felt quite under powered to me which I wasn't expecting and I had to keep quite a bit of throttle on to keep the control surfaces energised. Managed to hover and harrier ok but it was a little worrying doing some of the manoeuvres due to the flexing so I've decided to make a couple of changes...

    I'm going to build the fuselage up into a box to give it some torsional rigidity (first snap roll I did looked like a jump to light speed as the wings turned and then the rear end followed later on!) and change to a 1400kv motor on 3S. Will then build up the wings into a KF4 airfoil which should increase the stiffness and allow it to handle the extra power from the 3S set up.

    Other than that though it felt pretty good, just very very flexible and wobbly :D

    Only bummer was when I brought it in to land I managed to pull the motor mount off so will re-jig that I think but for a maiden of spare parts it went pretty well :)

    No video though as it was just far too dark. In fact I'm surprised I managed to see the thing enough to complete the flight if I'm honest! Hmm, maybe lights for the next flight???? :D
     
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  8. TomMonton

    TomMonton Administrator

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    You mentioned being a little too flexy.

    I didn't care for the extra twist I was experiencing and added some basic ribbing to tighten some of that up.

    That narrow slice of 3mm was then glued over the ribbing.

    This worked well for me. [​IMG]
     
    Last edited: Dec 16, 2018
  9. Sterling101

    Sterling101 Top Gun

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    Now solid as a rock!

    1400kv motor installed and running on a 3S 1000mah.
    AUW with battery is now 465g so it's gained 100g from all that work so not too bad really!

    Will design the KF4 airfoils tomorrow and stick those on and maybe do some tail bracing to keep it a bit more solid but other than that it's ready for another flight.

    IMG_20181216_233212.jpg
     
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  10. Boxermad84

    Boxermad84 Administrator

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    That's awesome, I love it!

    Jay, from www.frcfoamies.com
     
  11. homey666

    homey666 Top Gun

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    Ya! Agree 100% with Jay. Nice.

    Peter
     
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  12. Sterling101

    Sterling101 Top Gun

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    That'll do - KF4's all done and shaped and Tracy let loose with the Sharpies again :)

    Now to play the waiting game for the weather...

    IMG_20181218_230342.jpg
     
  13. What are you at for weight now?
     
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  14. Sterling101

    Sterling101 Top Gun

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    470g (16.4oz) with battery and according to eCalc the prop/motor combo should put about 800g out so should be spirited enough.

    Will see how it manages when the weather dries up and calms down...
     
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  15. Wow, that big and so light.
     
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  16. Sterling101

    Sterling101 Top Gun

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    I know! I've finally built a light plane! And it's only a 3 foot span so not too big
     
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  17. Sterling101

    Sterling101 Top Gun

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    Maidened it this morning in possibly the worst conditions I could have chosen!

    Winds were a steady 12MPH all morning and it started raining just as I arrived at the flying field.
    Wasn't going to go home without a flight though so sent it up anyway and I have to admit it flew ok considering the weather conditions. Found it was blowing it down field quite a lot from all the wind so couldn't harrier or prop hang but it proved the plane will fly and seems to be well balanced. Next step will be some undercarriage I think and maybe a swap to the 8x6 prop over the 8x4 for a bit more bite...

     
  18. Sterling101

    Sterling101 Top Gun

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    Went crazy this afternoon and printed a wire undercarriage mount and bent a bit of wire up with some oversized wheels on it.
    Well, seeing as the grass field is more of a marsh at the minute I figured an SBach Tundra might be fun!

    Tail wheel is on a braced mount on the rudder itself and made of 2mm wire bent with a loop to provide a bit of spring. Have also re-enforced the rudder with some fibreglass cloth and PU varnish.

    The wheels are at a reasonable angle, but the camera made it look much worse when I took the shot. Being a slot mount I can swap the wheels out for something a little less aggressive once the weather calms down and it dries out :D

    All told it's put about 70g onto the weight but that should be offset by either the 8x6 prop or the 8x4x3 I've got kicking about....

    IMG_20181223_195726.jpg

    IMG_20181223_195804.jpg
     
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  19. Tomorrow it will have a edf in it. ;)
     
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  20. Sterling101

    Sterling101 Top Gun

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    Now that's just silly talk - it'll have two :D
     
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