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Lama V3/V4 and Kob E-Sky Lama V3 and V4 and Kob |
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02-04-2008, 09:36 PM | #1 (permalink) |
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Help?!? Proper flybar to blade grip angle on Lama v3? Help!
I have an Esky Lama v3 and I've done several mods. It seems to fly great except that it tends to drop altitude with forward flight and I don't know that I'm getting all of the proper lift because since I did the metal upgrades to it, I'm not sure of the proper angle between the flybar and the blade grip. It was originally close to 90 degrees, but I read an article in RCHeli magazine about coaxials and it discussed the angle to be proper with "an angle of 45 degrees to the leading edge of the blade", not 90 degrees to feather. I guess for all that I am learning about heli flight physics, I'm not thoroughly grasping the relationship that this angle has to flight characteristics. Can someone explain what will realistically happen in both hover and forward flight with the angle of the flybar greater or less and what I can look for to "dial it in"? Also, I'm considering getting a shorter flybar (or an adjustable one to experiment with), but again, I'm not sure what to expect with a shorter/longer flybar in regard to the flight characteristics. Could someone/anyone PLEASE help a newbie? I'm doing all of my experimenting on this cheap model so that I can better understand future adjustments on my Belt CP and future helicopters. Please help..... Thanks
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02-05-2008, 06:07 PM | #2 (permalink) |
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You seem a little unclear on which angle you're talking about. When viewed from above the disk looking down, the angle from the flybar to the leading edge should be about 45deg. as mentioned in the article, this is determined by how the flybar fits in the head and is not adjustable. What you can adjust is the link that connects the flybar to the blade grips. If this is out of adjustment, the result will be a "toilet-bowl" effect from the rotors fighting each other. Basically, the flybar should be level when viewed from the side and the grips should also be level. Once you have this set, hover the heli and see if the upper blades are tracking correctly, if they aren't, make a small adjustment to this link, if it gets worse, go the other way. Do this until the blades are tracking correctly.
As for flybar tuning, a shorter flybar or a flybar w/ lighter weights will make the heli more responsive at the expense of some stability. I tried to adapt an optional flybar for the Hirobo coaxial to my V4 in an attempt to make it fly more agressively. This flybar was much shorter than the original and had small paddles on the end instead of dumbell weights, it made the model almost uncontrollable. |
02-06-2008, 12:47 AM | #3 (permalink) |
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Join Date: Mar 2007
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The flybar is a gyroscope. Newton said an object in motion tends to stay in motion unless acted upon it by an external force(not sure about the exact wording). So if you are moving forward, the flybar will tend to stay in the same orientation while the heli leans for or aft. The connection to the grip from the flybar will buffer out those momentary inconsistancies. The paddle angle(Hiller) will help adjust the flybar to coinside with cyclic inputes. Hence the washout system. So the flybar really is more of an issue with cyclic input rather then weather or not the paddle angles reflect collective input. Just look at the way the flybar can teater freely. It will try to maintane the same disc if the heli rocks forward or back. The paddles aid in changing angle when you introduce say a left aileron input. This changes the angle of the disk thru the washout linkage by way of the airodynamics of the paddles. Thus aiding the stability during a cyclic change. So the flybar really does nothing to change pitch so much as it effects the results from the heli bouncing about as from wind and other atmospheric issues. The ratio of cyclic input to Bell-Hiller(flybar) input will effect how much influence the flybar has. Just make sure you got Zero pitch on your flybar with zero pitch on the main blades. And that all your linkages are horizontal with zero pitch.
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