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Mitja |
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Joined Nov 2009
3 Posts
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Gyppy BR
Hello everybody, I made the first flight in the guppy this weekend, but could not fly a lot, because the wind was very strong, had some problems, my 9x4 folding prop has not yet arrived, I used a 10X4.7 I use in shock , but found it too torke when accelerate it all loops, not yet know why this is happening, if anyone knows help me, another feature that I did not like and I will review the wings, he is in stall falls sharply the left side, left the CG as stated in the plan, but I think I'll leave it back, I found a little heavy on the nose landing.
Guppy BR TOTAL WEIGHT 550G Engine, e-max 2228 speed pro tower 20th servos, 3 tower pro 9g and 1 dynam 8g corona synthesized receiver zippy battery 1200MA Radio JR 388S |
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Joined Nov 2007
32 Posts
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Hello Guys!
I want to build this plane, but I don't like planning programs, so my question is that somebody have the plans in the size of the balsa sheets, which I can print in a laser printer, and than I can ironing it to the balsa, or use paint thinner to copy it to balsa. This part of the building that I hate so much. So I need a little help to it. Feel free to mail me! Thanks! |
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Joined Nov 2007
32 Posts
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Thanks for the answer. I can print now the plan in laser printer, and my thechnique is working. I cut some parts right now
I think it will be a slow work, because I have no so much time around now, but I hope in the winter I can finish this beautiful plane. I have all the things to do that. I'll share photos with you when I have some. Thanks the plans, the building guide, the pictures. These things helps so much for me.Kazoo |
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Singapore
Joined Nov 2001
793 Posts
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Quote:
An electric sailplane will fly like crap with a big fixed prop on the nose. Furthermore, you must understand how a powered sailplane is being flown in the first place, in order to reap the benefits of the design. Firstly, the sailplane is meant to be flown with no power most of the flight time. The power system is designed to climb the model to thermalling altitude. In competitions, only limited time is given for power on climb. You'll have at the most 50 seconds or a minute to climb as high as you can, and beyond that, points will be deducted. After that, you really want the model to be as aerodynamic clean as possible to stay in the air longer and hopefully, catch some thermals to extend the flight time. As such folder props are almost mandatory for such designs. For such purpose, large folder props are often utilised to give near or at vertical climb. Climb angle at 60 degrees usually gives the fastest climb to height, due to the combination of static thrust from the power system and the lift created by the wings. For the steepest climb, you will want to use the available power from your powerplant to yield the optimum static thrust by sacrificing some prop velocity. For outrunner motors, props with lower pitch will be used and motor/gearbox combination will drive very large prop at much lower rpms. And for this reason, flying with strong wind will be very challenging, as the low prop velocity will make your glider having a hard time penetrating into the wind. In fact, it'll be easier to penetrate into the wind with the motor off and the prop folded. For your case, your big, low-pitch fixed prop will not fold and still stick into the airstream, and is only making things even harder, as it will be, as the matter of fact, being turned into a big airbrake, especially so if it is left windmilling. In such conditions, the model will sink faster than your average sport powered plane, when the motor is cut, not to mention the torque of the big spinning prop doing all the funny things on your model. That could explain why your model lands hard. I'll say, unless you are very sure, do not make too many changes to your model yet, especially the CG positions. Go for a proper folder prop and remember to program motor brake in your ESC. Go fly it and see if it turns out better. You'll still get the upward pitch moment and some left torque roll everytime you bring up the throttle, but try to hold the sticks to correct it until it has climb to good height, then shut the motor and trim the model to fly straight and level with the lowest sink rate. Once done, either you land your model, or let it glide around until it is low enough and send it climbing again with power. This time, remember how much elevator and rudder trim is required to correct the pitch and roll tendencies, to facilitate mix programming in your radio later. Last but not least, powered glider spend most of its flying time gliding without power, or climbing at full or near full power. There's little use for throttle positions in the middle. Hope these help. |
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