MikeEast
Posts: 3222
Joined: 10/18/2003
From: Nederland,
TX, USA
Status: offline
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This is a comment regarding 3D setup that is very relevant and important so I thought I would post it here as well  This is important and could save your plane so please read carefully.
quote:
ORIGINAL: hoveralot
Thanks a lot for the suggestions, tomorrow I´ll try all that, I guess it has something to do with thrust as you mentioned so I´ll see what happens know that it has an ultrathrust muffler (91FX 15x4W APC).
To get more than 45º I´ll get some large servo arms because did some testing in AFPD and there is a real difference between 45º and 60º when doing waterfalls.
I´ll tell you tomorrow
Hoveralot,
Before you do that be sure of what your servo can handle. I am not saying do not do it, just be sure that you won't strip the servo when you do. What happens when you put on a longer servo arm is you lose some mechanical advantage. When you do this you must be sure that the servo has enough mechanical power and physical gear strength to be able to handle the load coming back from the control surface. Remember the servo is pushing the control surface, but in flight the control surface is pushing back! This is due to the winds force on that big old control surface out there while the plane is flying. As you move out on the servo arm it gets more difficult for the servo to handle the force. If the mech advantage is lost and the servo gives you can get a few things happening.
1. If its not a digital servo the control surface will physically push the servo back. and or strip the gears.
2. If it is a digital it may not get pushed back but it can and will strip the servo once you reach the limit on the servo gears, they simply break and the servo strips if they cannot withstand the load. Ask me why I know this. 
That is exactly why 3D folks are going to digital servos with metal gears. You go with a servo that is about 2 times what you really need and with metal gears you are ensured that the servo will hold and the gears will not strip with as long of a servo arm as you want to use. What you give up in mechanical advantage by lengthening the servo arm, you MUST make up for in the physical strength of the servo.
Now, I will tell you why I know this.
I stripped a set of Futaba 9151'sm (plastic geared digital) doing a knife edge loop last year, TWICE. I wanted to get more throw for waterfalls so I went from a 1 1/4" servo arm to a 1 1/2" servo arm. When I did I got what I wanted, BIG throws. 60 degrees plus. But when I would do a knife edge loop, at the bottom in the last quarter where you are pouring the coals to the rudder and correcting with the elevator to maintain course (THWACK) the gears popped on one servo. Sounded like a 22 caliber rifle. Fortunately the elevator half totally stripped and went to neutral and I landed with no problem. But I did not understand the problem, replaced the servo gears and lo and behold a few flights later it happened again. Then the light switch went off. I switched to a 333 in oz Titanium geared servo and that was it, not more problems. Of course this was in a 37% Scale plane, but you need to be sure that you take the appropriate actions for your plane.
< Message edited by MikeEast -- 8/13/2006 3:37:42 AM >
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Mike East
AMA793948
RCU Reviews
Moderator: 3D, IMAC and Pattern Forums.
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All Forums >> RC Airplanes >> 3D Flying! >> RE: HOW-To..3D maneuvers 
RE: HOW-To..3D maneuvers - 
Are you kidding me? That is a TON of planes!!! I gues I cant say much though, I have about the same amount of $$ invested in 2 planes. I think you are the wiser of the 2 of us! 
