MikeEast
Posts: 3226
Joined: 10/18/2003
From: Nederland,
TX, USA
Status: offline
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There are a few issues you are probably dealing with.
1. Inexperience. Once you get accustomed to hovering you can bring most any airplane right down and touch the tail if you choose to do so.
2. You MIGHT be a little bit nose heavy. If you roll the plane inverted and do not hold up elevator the plane should very slowly lose altitude. You should need just the slighest breath of down elevator to hold level inverted flight. If you dont need any elevator or the plane climbs without elevator while inverted you are tail heavy enough. I personally would not want to setup my airplane for hands off inverted JUST so its easier to hover. It will wreck all of the other important flight characteristics. Again, level flight with just a breath of down elevator to hold level flight. If it take a lot of down elevator you are nose heavy, if it takes no down elevator its too tailheavy.
3. Hovering is like balancing a pencil in your fingertip.. Its a very delicate balance that is EASILY upset. Backing an airplane down for a tail touch takes a lot of skill and practice... There are TONS of guys that have put in the hours and make it look easy to back a plane down, but looks are deceiving, its HARD . It only looks easy because they have practiced and practiced and practiced and practiced some more. Descending vertically tail first is not something that an airplane wants to do and its going to fight you all the way until you learn how to work with it. One key element is throttle control, you need good throttle servo resolution so that you can make very fine throttle adjustments. ESPECIALLY while you are learning. If you resolution is too tight like 60/60 ATV(endpoints) or unbalanced like 80/120 ATV(endpoints) then the throttle response is going to be too fast in places and too slow in others. Ideally you want a short servo arm and long throttle arm so that you can maximize servo resolution like 120/120 ATV(Endpoints) That is, every click of the throttle makes the smallest move possible, If your resolution is too low 60/60 or even 80/80,, then each click makes too big of a change in the throttle and you end up climbing with one click up and falling with 1 click down on the throttle stick.. You need the throttle to be very soft so that you can move the stick 1 click at a time and very slowly EEEEASE the airplane back down to the ground to touch the tail. If you are overdoing the throttle and trying to horse the plane down to the ground its going to be really hard for you to learn. Big throttle movements bring erratic engine torque into the equation and that torque is going to be jerking the airplane around and you are going to have to fight that much more with the other controls. Once you get nice high throttle resolution and you can make nice small changes on the throttle stick to very gently increase the vertical ascent or descent in a hover its going to be a lot easier to touch the tail.
Another thing is learning how torque and your prop comes into play at all times in a hover. Again, that is why you need a good throttle setup. A lot of times you may notice your plane start to want to torque roll a little so you add aileron, then more aileron and its still wanting to torque roll. SO you bump the throttle, which increases prop wash to make the ailerons more effective but now you are going UP again!!! UGH!. So whats the solution? Is your props wash not effective enough? Do you not have enough aileron throw? Is your throttle too sensitive? Well, that is why you need to eliminate problems before you ever fly the first flight. Get the throttle resolution optimized, then make sure you have the right prop for 3D on your plane, then its just a matter of getting the aileron throw and expo setup so that the plane responds like you want it to when you add aileron. If you dont have enough throw or too much expo, then the airplane will not stop torque rolling like you think it should, so increase throw or reduce expo. But be aware of the consequences of increase in roll rate during other maneuvers where you use high rates. If the ailerons are too sensitive, reduce throw or expo until it does what you want it to do.. I have even switched to hovering on low aileron rates on planes that have very effective ailerons like my Extreme Flight Yak. A good rule of thumb is to set your rates so that you only have the throw you absolutely need for your most demanding maneuver, anything more is just going to make things jerky.
Now, dont confuse this with #3,,, people who have become very proficient at hovering CAN horse the plane down right in front of them because they have become VERY good at balancing that pencil on their fingertip. They can do it with a poorly set up plane that in the hands of a human would fall out of the sky. Watching Kyle Woyshnis or Mark Leseburg chop the throttle and letting the plane fall 6-10 feet in a chunk as they back it down to the ground looks GREAT and they make it look easy.. It is easy ONCE YOU LEARN TO DO IT... But until you do, the best place to start getting a plane down on the deck is with good throttle management as I mentioned above.
4. A waterfall takes not only a slightly tailheavy plane it takes a LOT of elevator throw and probably the most overlooked necessity is POWER. You need a good strong engine that is a stump puller for an aiplane of your size. You need to be able to get the momentum going to pull the plane back over the top of the waterfall. Also you should be in and out of the throttle to get the waterfall going. Hard on the power when the nose is from about 10 o clock to 2 o clock out of the power as the plane flips over then back in... Its sort of like a slingshot effect. IF you leave the power in its just easier to get out of line.. 1 more thing, you have to learn to use the rudder in a waterfall to keep the plane upright. Once it winds up it does not take much, but you may have to really work the rudder until the speed of rotation really winds up, then momentum takes over.
< Message edited by MikeEast -- 7/30/2007 3:27:46 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 - 
. I just recently ordered a 
ive been trying to move on to harriers and to do one right do you all ways have full elavator in or is every plane a little different because i add in a little trottle just enough to keep from sinking and i cant seem to keep her from going in to a hover or flipin on over