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  1. #1
    AgCat1982's Avatar
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    GWS PT-17 Stearman

    I would appreciate help from someone who has the GWS PT-17. I have mine completed, ready to test fly using a 400F outrunner brushless motor. The only problem is the CG. The instructions are not clear about it. They say 0mm + 10 from the leading edge of the wing. Not which wing. The photo does indicate the lower wing, but, not what 0mm + 10 means. 0mm + in which direction?

    Also, where do you hold a bi-wing when balancing? It's tail heavy and I need to correct it. I just don't want to add more weight than necessary. With the Kokam 1500 11v battery all the way forward and setting on the edge of the mock radial, it still appears to be tail heavy. That is with the wad of clay, too.

    It seems I may not be checking in the correct place and I don't want to wipe out on the maiden flight.


    Thanks
    Sticks,
    My home RC video\'s: www.weflyelectric.com
    My planes and projects are in my profile.

  2. #2

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    RE: GWS PT-17 Stearman

    you have to hold the plane upside down and balance from the bottom wing. i have my cg as close the the leading edge. this plane is really tail heavy so push your battery as far foward as you can. i had to use quite a bit of clay to get it balanced.

  3. #3
    AgCat1982's Avatar
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    RE: GWS PT-17 Stearman

    Thanks, that is what I did. I had to cut out a hatch in front so the Li-Po would set almost on the motor. Still need the clay and it seems to balance where you suggest. The brushless is about an ounce lighter than the supplied motor is why I am having to move so far forward without adding unwanted weight. The hatch still looks good the way I cut it.

    Ready for maiden. I hope. I have lots of time on others, just no bi-planes.
    Sticks,
    My home RC video\'s: www.weflyelectric.com
    My planes and projects are in my profile.

  4. #4
    AgCat1982's Avatar
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    RE: GWS PT-17 Stearman

    O.K. It flies. Now another question about bi-wings. This plane seems to be balanced correctly. However, both flights I have made have started out with it climbing almost straight up requiring a tremendous amount of down trim to try to level off. Then when it was just about to level, it nose dived requiring me to hold a lot of up elevator. No matter how I tried to get trimmed level flight, it would not. Either hard up or hard down.

    I have checked the controls. there is NO slack in the elevator connect rods. It does not try to hang in one spot. I have digital trim so I am applying it in small steps.

    I have seen this in other planes of mine, but, it turned out to be warped elevators, due to moisture from starting to rain and elevator being uncovered balsa sheet, which caused it to "pop" across the center point. This planes elevator is straight and has no catch points.

    Still balanced wrong? Just this plane? Any help would be appreciated.

    Thanks
    Sticks,
    My home RC video\'s: www.weflyelectric.com
    My planes and projects are in my profile.

  5. #5

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    RE: GWS PT-17 Stearman

    Hello there,

    Just a thought, theres nothing lose sliding around in the plane is there?

    Joseph

  6. #6
    AgCat1982's Avatar
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    RE: GWS PT-17 Stearman

    Thanks for trying.

    Checked that. At first I was sure the battery was sliding back and forth. Secured it and did not help. Nothing else moves.
    Has anyone noticed if badly tail heavy will cause this?
    Sticks,
    My home RC video\'s: www.weflyelectric.com
    My planes and projects are in my profile.

  7. #7

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    RE: GWS PT-17 Stearman

    Sounds like you might still be a little tail heavy. Also, limit the elevator throws - the Stearman is pretty pitch sensitive and acts a little like the low wing warbirds in that respect.

    More Stearman info on this site

    http://www.novellahub.com/

  8. #8
    AgCat1982's Avatar
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    RE: GWS PT-17 Stearman

    Thanks Wolfewind, however, I think it's the other way around. I was so afraid it would be so sensitive that I set the throws to be not very sensitive on my transmitter. Way too much. I flew again today and I think I see what it may be. I am use to touchy controls and when the plane was pointing straight up, I was applying just a little down elev and it was not nearly enough. Then when I would finally get it to go down and try to add a little up elev, I wasn't adding fast enough and it would go into a dive. I have set it back to the normal way I fly, but, the temp was 30deg's and I did not have gloves.[&:] I will have to try it later. Another perfect landing!

    I do believe you are right about the tail heavy. I hate having to make a plane balance with dead weight.[>:] I love the power I have with this thing. It will climb straight up to about 75ft and just hang there until I pitch it over! If I could get rid of the clay, I think it would climb instead of hanging.

    Thanks for the web site.
    Sticks,
    My home RC video\'s: www.weflyelectric.com
    My planes and projects are in my profile.

  9. #9
    CorsairJock's Avatar
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    RE: GWS PT-17 Stearman

    OK, now I have another question:
    Which wing struts go where?
    The instructions really suck on all GWS planes, but experienced builders can usually figure things out. But in this case, we are dealing with a bi-plane, which involves getting the wing incidences correct (or you will have a really bad flying plane, maybe that's the problem with the one that agcatsbest has).
    There are a total of 10 wing struts: 4 relatively short "B" ones and 6 relatively long "A" ones. The 4 "B" ones are in 2 different lengths, and the "A" ones are 3 different lengths. The instructions have a drawing which depicts the struts before they are detached from the plastic sheet, but this drawing is not only had to decipher, it is also incorrect/ not an accuarate representation of the actual sheet.
    Obviously, the "A" struts go to the wing to wing attachment points and the "B" one for the fuselage to upper wing, but asside from that: which ones go where? It would have been helpful if the instuctions listed the actual lengths of the struts, but they didn't.
    So, HELP! If no-one knows the answer, does anyone know if top wing should be positive to bottom wing, same incidence, or otherwise?

    BTW, I have geared brushless motor/ 3 cell Li-Poly, and am hoping for 3D performance
    Avatar: Electric Powered, Highly Modified Hangar 9 Corsair
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  10. #10

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    RE: GWS PT-17 Stearman

    I had to add 75 grams (OUCH!!!) to get mine to balance. I used a BIG washer glued to the front of the fake motor and I still think it needs a little more weight. Mine flys the same way, either climb or dives. If you really throttle it back it will fly level for a while, then it will stall. Thanx Scott
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  11. #11
    CorsairJock's Avatar
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    RE: GWS PT-17 Stearman

    Flew mine today for the 1st time, WOO HOO!
    Came out weighing an even 18 oz with HiMax 2015/ 4100 geared (6.3:1) brushless, spinning APC 11 x 4.7 and driven by 3 cell, 1450 mAh Li-Poly. With battery compartment enlarged and battery ALL the way forward, no weight needed for balance (about 5mm behind lower wing leading edge).
    Needed slight amount of down trim. Loops from level flight with no effort, very tight. Did barrel rolls, snaps, and tried hover: it will hover but only at near full power. No reserve for pulling it out (up). I could go to a 11 x 7 APC, which would get me an addional 6 ~ 8 oz thrust, but Castle Creations 10 amp speed controller keeps cutting out when I use that prop. Motor is good for it, I need to find a speed controller with a little higher amp rating.
    Only flew it for about 5 minutes: a little on the windy side (about 8 mph according to weather burea), so I cut it short.
    This thing looks like it will be a blast to fly on a calmer day.
    Avatar: Electric Powered, Highly Modified Hangar 9 Corsair
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  12. #12

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    RE: GWS PT-17 Stearman

    Hello,

    I also have this crate. It flies extremely nimble, and is, tailheavy with the stock setup, and battery.

    here is a good solution that will help balance it out. Get a bigger (heavier) battery. You said you use a 1500? get the 2100 3s1p from thunder power, or the 2200 3s1p from Polyquest. Either one slips in with little or no cutting, and helps a great deal in balancing. Also you get longer flight times

    Another way to balance it out: get a bigger motor. I have successfully flown with near vertical performance, a johnson s600, 2200 3cell lipo, and a 10x5 prop. It was truely ammazing for 5-6min. Then my esc locked up my controls!!! it porpoised, and dove at 45 to the ground snapping her in half! more epoxy.
    Once I can afford a 30amp esc the johnson goes back in I think a s480 would be almost perfect, it would eliminate any "dead" weight. You would gain some thrust, and balance out correctly.

    Another trick? Use a gas prop...they do not break in a crash, and help the cg. I use these gas props a lot for testing. they will not break...the shaft bends first...You can straighten the shaft right back, at the field, with your hands!

    Just some solutions to a common problem.
    "these are my humble opinions after throwing too much money into crashing."

    theHarpmanDan

    p.s. I flunked spelling. If you have some pet peave about spelling than tough titty....lmao.

  13. #13

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    RE: GWS PT-17 Stearman

    doh! Look at the wing loading of this crate!

    I forgot to mention how much room there is to play with wing loading wise. Dont be afraid to add some weight and try this plane in the wind...

    It is the light wingloading that makes hard to fly in the wind. The day I tried the s600 in it, it was blowing over 10mph, with gusts up to 20. It had no problem with the wind whatsoever. It went from twitchy (s400) to on rails(s600). If you want it to track like on rails put the cg in line with the leading edge (lowerwing). I was amazed how well it tracks.

    I will give more info on this crates limits as I learn more.

    theharpmandan

    PS tape the wings if you do add much weight, I almost folded it in half!

  14. #14
    jrotor's Avatar
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    RE: GWS PT-17 Stearman

    Hi,
    I'm looking at a brushless motor that has a 28oz of thrust, do u think it'll be enough power for this PT-17 ?
    Thanks.


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