View Full Version : omei glider "gear"
07-31-2006, 01:42 AM
hi all and thanks for the input from everyone .
i would like to ask the question of anyone that has a omei glider for the best in gear I.E. servos ,batts, etc ....
thanks for any help .
08-01-2006, 12:06 AM
Hi Jimmy, I found a thread on the Omei in the Wattflyer Archives, it's here; http://www.wattflyer.com/forums/archive/index.php/t-2413.html
There are threads on RCG also, many flyers upgrade the motor to a brushless but I've seen them fly with the stock 550 brushed. One of the simplest and least expensive upgrades is to get a Graupner "CAM" folding prop (same diameter and pitch as the supplied one) which will improve the climb. In a glider this large (nearly 2 meters) I'd suggest HiTec HS 81 servos in the wing but you might be able to use smaller ones if they have enough torque. Same for the elevator. For a battery, the stock motor (and most brushed motors, for that matter) will run well on 9.6 volts (8 conventional cells) but if you get over that, like the 11.1 volts from a 3 cell LiPo it shortens motor life considerably. As for ESCs, a good 30a-35a controller should be safe.
I don't have this glider myself but have seen a few flying; They're decent flyers with a stock set up and better-than-average with a brushless motor.
You may want to get some other opinions, if you do a search for "Omei Glider" it will point you to other threads.
08-01-2006, 12:37 AM
Hi Ron , thanks for all your help .
with all my questions . if you remember i'm the same guy with the "ASCENT" problems i did get a few "OK" flights , "OK FLIGHT" code word for "i did not need more glue to fix it after said flight" . i'm still not sure what i'm doing wrong with the "ASCENT" , seems to nose heavy down wind and a bit of a stall upwind ,I.E. i have to reset the trim / motor on / motor off/upwind and down wind . i did add remove weights checked the C.G. e.t.c. but the climb was still slow and it dolphin on the up leg and nose down on the down wind leg .
thanks for all your help and input RON
08-01-2006, 01:23 AM
Hi Jimmy, yes, I remembered our discussion about the Ascent. I may be able to help you with that model now that you've flown it; What you're describing is two different problems and there's a way to fix both of them. First (and this will help you when you fly the Omei or any other powered glider) a little basic aerodynamics, nearly painless, I promise!
Most aircraft, with a few exceptions, have a slight difference of angles between the wing and horizontal stabilizer; That is, if you look at the aircraft from the side, you will see that the wing trailing edge is slightly lower than the leading edge. Same effect as "UP' elevator, except it's fixed, built-in. This difference of angles is called "Decalage" and is designed to allow the wing to fly at the optimum angle to provide lift. Too much angle (L.E. to high) will create to much drag; Not enough angle, not enough lift. OK so far? Gliders, even powered ones, spend 90+ % of their time gliding so the decalage is designed for optimum lift/drag at glide speed. Maybe 10-15 mph. So far, so good.
But now we add power; With power comes speed, increased airspeed to be exact. Twice as much speed, three times as much...what does the decalage do now? Points the nose nearly straight up, much higher than the power (motor) can sustain,...stall. All powered gliders have this happen, some worse than others. The quick fix is to hold "Down" elevator" during the climb. Some designers build in downthrust. Others "mix" (couple) the elevator trim to the throttle, more throttle, more down trim; Motor off, netural trim. If you understand this and expect it, it merely become a trait of powered gliders and you compensate with the elevator. No problem.
That's why the model is pitching up during the climb. But I think it's still nose-heavy. Try this; Use the elevator to hold the nose at about a 30-40 degree climb under power, try to not let it stall but climb as fast as it can. Once it gets pretty high, more than 300 feet, turn it directly into the wind and cut the power. Let it settle down, it may stall at first as it slows down. Once it's at glidespeed (which may seem like it's not even moving if you're used to powered models!) what does it do? Does it flatten out and come down fast, regardless of wind direction? Put in a couple "clicks" of up elevator. Now what? Is is gliding OK? Does it slow down and follow commands smoothly? If so, That's a good "glide" trim. If it still seems too fast and descends quickly, it's still noseheavy.
The Ascent is a good little glider but it needs trimming and a little patience. Hang in there, we'll get you flying!
08-02-2006, 03:43 AM
and thanks again my friend ,funny how life goes ,for the age of 20 - 32 i flew hanggliders for a sport i did study meteorology/micrometorology, and aerodynamics and flew off a few 1,800 foot launch sites from minnesota to tennesee . and when i bought my first R/C plane thought "hell i dove off a cliff this will be easy " as i'm 51 now guess all was a little easy back in the day .ok now to the point , thanks again for your input . i was working on all you said "under no power" from 5 to 10 mph winds to work on the trim issue , later a little power after the sun starts to set .
you have made me think about the "flight" rather than think about the "flying" thanks again ron you are a great help.
08-02-2006, 05:06 AM
Hi Jimmy, you're more than welcome for any help I can provide. I didn't know you had an aeronautical backround, sorry if my post was overly simplistic. I sometimes rattle on and on, but figure if others are reading the reply, it might help somebody!
If you can get the power-on phase of a powered glider trimmed out, the glide is usually the easy part. I've seen the Ascent "speck out" in lift, they will glide once you get them trimmed. Keep me posted on your progress, any other questions or problems, fire away!
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