nose heavy
04-15-2013, 04:35 PM
#26
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RE: nose heavy
Speedracer: My rails aren't straight, they are cut to the wing's shape. It's a mid wing so both the the canopy and fuse are cut to fit the wing. I routed through my work shop and dusted off the old incidence meter.
Should I get the stab at 0 degrees and compare the wing to the stab and the down and thrust angles with the stab at 0?
Tom
Should I get the stab at 0 degrees and compare the wing to the stab and the down and thrust angles with the stab at 0?
Tom
04-19-2013, 03:53 PM
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RE: nose heavy
Speedracer:
Sorry for the delay but my fingers and my lawn mower's muffler had an issue. Two well blistered fingers later I got to work on the Edge.
Ok, with the stab @ 0 Degrees the wing is at 0 and the engine has 1 degree of Up thrust.
I adjusted the engine to 0 thrust (one washer behind the upper engine mounts) and shimmed UP the front of the wing 1/64" to get it to +.5 incidence.
The weather here may not be conducive to flying the next couple of days.
When I do get the Edge up, what is my task?
Tom
BTW: I centered the elevator and the trim on my radio to neutral.
Sorry for the delay but my fingers and my lawn mower's muffler had an issue. Two well blistered fingers later I got to work on the Edge.
Ok, with the stab @ 0 Degrees the wing is at 0 and the engine has 1 degree of Up thrust.
I adjusted the engine to 0 thrust (one washer behind the upper engine mounts) and shimmed UP the front of the wing 1/64" to get it to +.5 incidence.
The weather here may not be conducive to flying the next couple of days.
When I do get the Edge up, what is my task?
Tom
BTW: I centered the elevator and the trim on my radio to neutral.
04-19-2013, 05:41 PM
#29
RE: nose heavy
Tom, then next thing is to go fly the airplane. in the sequence of trimming and airplane for aerobatics getting the CG right is step 1 as it influences everything else. Everything is a compromise. Some things that will improve some flight aspects can take from others.
On the next flight take note on what elevator trim you need. If you only need a couple clicks of up that would be OK. Anything more and you would be nose heavy. The positive wing incidence should eliminate the need for any up trim if the CG is spot on. This also allows the fuse and engine to fly at zero. This will show up later on verticals and knife edge. Once the CG is nailed down you can pull some verticals to check the right thrust. use a little right rudder when rounding the corner once vertical ease off and see what she does. What you are looking for is a strait vertical for about 150 feet and then a slight drift to the left as airspeed slows.
Once you have these down we will talk about radio setup.
On the next flight take note on what elevator trim you need. If you only need a couple clicks of up that would be OK. Anything more and you would be nose heavy. The positive wing incidence should eliminate the need for any up trim if the CG is spot on. This also allows the fuse and engine to fly at zero. This will show up later on verticals and knife edge. Once the CG is nailed down you can pull some verticals to check the right thrust. use a little right rudder when rounding the corner once vertical ease off and see what she does. What you are looking for is a strait vertical for about 150 feet and then a slight drift to the left as airspeed slows.
Once you have these down we will talk about radio setup.
04-22-2013, 05:49 AM
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RE: nose heavy
Speedracer:
First off let me thank you for your help. It's guys like you that make RCU great.
So, I took her up yesterday. Take offs are quicker (shorter take off roll). Once to about 100 ft I leveled her out and added 6 clicks of up trim. O clicks of aileron or rudder trim.
I did a couple of circuits and then pulled up in a 45 and rolled inverted. With no input and at 75% throttle she stayed on line for about 100 feet or so then slightly tucked toward the canopy.
Once I turned around I flew her away from me pulled her up adding a touch of right rudder. I then eased off the rudder and let her go vertical. As you said, she pulled slightly to the left when losing speed.
Loops on low rate are big and slow. On high rate they are quite tighter without any tendency to snap.
Rolls on low are axial and smooth. On high the are twice as fast and still very axial.
Immelman turns are very smooth (I have to practice them more)
I did notice the rudder is very sensitive. I tried to Knife Edge and the rudder has way too much throw. It's not something I have done much of.
Snaps on low rate don't happen. On high rate she snaps quickly and violently.
Tom
First off let me thank you for your help. It's guys like you that make RCU great.
So, I took her up yesterday. Take offs are quicker (shorter take off roll). Once to about 100 ft I leveled her out and added 6 clicks of up trim. O clicks of aileron or rudder trim.
I did a couple of circuits and then pulled up in a 45 and rolled inverted. With no input and at 75% throttle she stayed on line for about 100 feet or so then slightly tucked toward the canopy.
Once I turned around I flew her away from me pulled her up adding a touch of right rudder. I then eased off the rudder and let her go vertical. As you said, she pulled slightly to the left when losing speed.
Loops on low rate are big and slow. On high rate they are quite tighter without any tendency to snap.
Rolls on low are axial and smooth. On high the are twice as fast and still very axial.
Immelman turns are very smooth (I have to practice them more)
I did notice the rudder is very sensitive. I tried to Knife Edge and the rudder has way too much throw. It's not something I have done much of.
Snaps on low rate don't happen. On high rate she snaps quickly and violently.
Tom
04-22-2013, 01:48 PM
#31
RE: nose heavy
Tom, sounds like you are off to a good start. As far as rudder throw goes I would usually set mine so that at 2/3 to 3/4 throttle I could maintain altitude at knife edge on low rate and about 20% more at high. These type of airplanes need lots of aileron to get clean crisp snaps thats why I have a seperate flight mode for snaps that adds 15 drgrees more then normal mode.
The next step if you havent done so already is to check what I call the 4 quadrents of ailerons. What this means is to check to make sure you have exactly the same aileron deflection up and down right and left. If you bring up your ATV menue and you have everything set to the same percentage odds are your ailerons are not traveling the same. The actual amount is not important right now because once the travels are balanced then they are adjusted in unison with the aileron dual rate. Once you have them all set the same, go into the differential menue and adjust so that the ailerons travel 1/16" to 3/32" up more then down. This will make the rolls especially the vertical rolls easier.
Expo is a very personal setting. I have seen good pilots run very little and I have seen good pilots run alot. I start with about 30% and adjust just to the point where corrections are not quite obvious. This may feel soft to some so will take a little getting used to.
Play with your throttle curve some. The idea is to make mid stick your cruise throttle setting. Power output will be closer to 2/3 or 5/8. The curve allows you to dial it a little softer around the center so that slight throttle changes won't upset the flight path.
Advanced flying means flying the airplane with all 4 control functions at a time. The hurtle with this is getting used to using your left hand. Go out and practice a strait line back and forth 100 ft high and 150 ft out. Use turn around manuvers such as half cuban, humpty bump or hammerhead. Use the rudder, you will find yourself drifting in or out, steer the airplane with the rudder. I often have to hold rudder during most of the flight to keep the box depth the same pass after pass. Practice this until you can do the strait passes and turn arounds and maintain 150 ft box depth.
The next step if you havent done so already is to check what I call the 4 quadrents of ailerons. What this means is to check to make sure you have exactly the same aileron deflection up and down right and left. If you bring up your ATV menue and you have everything set to the same percentage odds are your ailerons are not traveling the same. The actual amount is not important right now because once the travels are balanced then they are adjusted in unison with the aileron dual rate. Once you have them all set the same, go into the differential menue and adjust so that the ailerons travel 1/16" to 3/32" up more then down. This will make the rolls especially the vertical rolls easier.
Expo is a very personal setting. I have seen good pilots run very little and I have seen good pilots run alot. I start with about 30% and adjust just to the point where corrections are not quite obvious. This may feel soft to some so will take a little getting used to.
Play with your throttle curve some. The idea is to make mid stick your cruise throttle setting. Power output will be closer to 2/3 or 5/8. The curve allows you to dial it a little softer around the center so that slight throttle changes won't upset the flight path.
Advanced flying means flying the airplane with all 4 control functions at a time. The hurtle with this is getting used to using your left hand. Go out and practice a strait line back and forth 100 ft high and 150 ft out. Use turn around manuvers such as half cuban, humpty bump or hammerhead. Use the rudder, you will find yourself drifting in or out, steer the airplane with the rudder. I often have to hold rudder during most of the flight to keep the box depth the same pass after pass. Practice this until you can do the strait passes and turn arounds and maintain 150 ft box depth.
04-22-2013, 02:59 PM
#32
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RE: nose heavy
Speedracer:
One thing I do on most of my planes is set differential on my ailerons with the servo arms. It's an old school technique I use by having the arm closer to the surface in one direction and further the other direction giving it more up then down about 1/8".
Yeah I'm guilty of not using the rudder but I do use the left stick quite a bit for throttle management through loops and vertical maneuvers.
This may sound like a dumb question but is it better to correct with rudder to keep consecutive loops on the same line or use ailerons? It kinda hit me in the head like a lead weight when you had me correct the upline for a stall turn with right rudder. What I'm saying is when I enter and at the top of a loop I use right rudder to keep the loop on line without it wanting to drift off course?
I do have 30% Expo on elevator and ailerons but none on rudder. I think I should add 30% Expo to rudder as well.
Although this is quite out of my comfort zone I find it a lot more fun then just doing circuits and a couple of loops and rolls.
Are you saying I should keep 150 ft out from the flight line? How small is this "box"?
Tom
One thing I do on most of my planes is set differential on my ailerons with the servo arms. It's an old school technique I use by having the arm closer to the surface in one direction and further the other direction giving it more up then down about 1/8".
Yeah I'm guilty of not using the rudder but I do use the left stick quite a bit for throttle management through loops and vertical maneuvers.
This may sound like a dumb question but is it better to correct with rudder to keep consecutive loops on the same line or use ailerons? It kinda hit me in the head like a lead weight when you had me correct the upline for a stall turn with right rudder. What I'm saying is when I enter and at the top of a loop I use right rudder to keep the loop on line without it wanting to drift off course?
I do have 30% Expo on elevator and ailerons but none on rudder. I think I should add 30% Expo to rudder as well.
Although this is quite out of my comfort zone I find it a lot more fun then just doing circuits and a couple of loops and rolls.
Are you saying I should keep 150 ft out from the flight line? How small is this "box"?
Tom
04-22-2013, 04:27 PM
#33
RE: nose heavy
Tom, I do remember the days of setting the differential with offset arms. I also remember that I could never get it quite rite. Using the radio to adjust gives you finer increments of adjustment. Take the airplane up as high as you are comfortable and put it into a strait dive with full aileron ( approx 1 roll per second ). it should roll as if there is an axle through the nose and out the tail. If it does not this would be a differential adjustment.
All heading changes should be done with rudder. Of course this is from the perspective of aerobatics competition. Using right rudder to keep your loops from cork screwing would be the correct technique. If you are being blown in or out by the wind you should rudder into the wind some so your airplane stays the same depth in the box or distance from the flight line. Do a hammerhead at one end of the field and watch how the downline drifts. This will give you a good indication of how much rudder is needed to maintain box depth.
Ok " The Box " IMAC no longer uses a box but has an airspace ulilization score. Pattern still uses the box. If you were to draw two lines at opposite 60 degree angles from your pilot station that would be the sides of the box. If you look at a 60 degree angle up that would be the top of the box. The box obviously gets bigger in all dimentions the further out you fly. Flying further out gives you more time to present your manuver to the judges but too far out will be difficult to see.
All heading changes should be done with rudder. Of course this is from the perspective of aerobatics competition. Using right rudder to keep your loops from cork screwing would be the correct technique. If you are being blown in or out by the wind you should rudder into the wind some so your airplane stays the same depth in the box or distance from the flight line. Do a hammerhead at one end of the field and watch how the downline drifts. This will give you a good indication of how much rudder is needed to maintain box depth.
Ok " The Box " IMAC no longer uses a box but has an airspace ulilization score. Pattern still uses the box. If you were to draw two lines at opposite 60 degree angles from your pilot station that would be the sides of the box. If you look at a 60 degree angle up that would be the top of the box. The box obviously gets bigger in all dimentions the further out you fly. Flying further out gives you more time to present your manuver to the judges but too far out will be difficult to see.
04-23-2013, 01:51 AM
#34
Senior Member
RE: nose heavy
ORIGINAL: jaka
Hi!
And remember! When moving the C of G rearward you can reduce elevator throw!
Hi!
And remember! When moving the C of G rearward you can reduce elevator throw!
The elevator is much more effective as it doesn't have to deal with the nose weight. The wing loading is reduced as well so the plane also flies better (less AOI needed etc) So most people discover that they want to reduce elevator throw in order to keep that "safe feeling" (sluggish response) they had before.
Some people increase the exponential to keep the slower response. Some reduce throws. Some need to do both. You've been flying the plane sometimes with a much less efficient elevator up until now. You really should expect the throw will need some adjustment.
The same things will happen with rudder during knife edge. In knife edge, the rudder has much the same job the elevator has in level flight and that job is increased by that "safe" nose heavy CG you got used to.
04-23-2013, 01:36 PM
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RE: nose heavy
Da Rock: Yes, the plane seems "lighter" on the sticks. I may have to add more Expo but since I'm "soft" on the sticks I may not need more Expo but less overall throw. Only time will tell.
Speedracer: You mean I should INTENTIONALLY send a perfectly good airplane in a straight DIVE? I will double check my aileron differential. While I'm at it I'll add more Expo to the rudder since it seems to throw the tail around quite a bit.
It's quite satisfying when little changes make such a large improvement on how a model plane flies.
Tom
Speedracer: You mean I should INTENTIONALLY send a perfectly good airplane in a straight DIVE? I will double check my aileron differential. While I'm at it I'll add more Expo to the rudder since it seems to throw the tail around quite a bit.
It's quite satisfying when little changes make such a large improvement on how a model plane flies.
Tom
04-28-2013, 04:42 AM
#36
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RE: nose heavy
Speedracer:
I had the Edge out yesterday and had the best flying experience EVER.
After dialing in 15% differential the plane rolls true.
I had the only IMAC experienced flyer in my club check it's CG and knife edge flying. With him taking it up at a 45 and rolling inverted she stayed online then dove slightly to level. Knife edge showed no coupling and rolls are now very true. Even slow rolls need very little correction when inverted.
It's amazing how much easier the plane flies when set up correctly.
Half cubans stay online as well as hammerheads. Vertical uplines need a tad of rudder to keep it straight.
The plane really makes me look like a better pilot.
I'm still keeping it up high when doing maneuvers until I'm comfortable.
I can actually fly slower and stay closer now that the plane doesn't need so many corrections.
Thanks so much for your help. I really want to fly more now and set up other planes in my hangar to fly as well as the edge.
Tom
I had the Edge out yesterday and had the best flying experience EVER.
After dialing in 15% differential the plane rolls true.
I had the only IMAC experienced flyer in my club check it's CG and knife edge flying. With him taking it up at a 45 and rolling inverted she stayed online then dove slightly to level. Knife edge showed no coupling and rolls are now very true. Even slow rolls need very little correction when inverted.
It's amazing how much easier the plane flies when set up correctly.
Half cubans stay online as well as hammerheads. Vertical uplines need a tad of rudder to keep it straight.
The plane really makes me look like a better pilot.
I'm still keeping it up high when doing maneuvers until I'm comfortable.
I can actually fly slower and stay closer now that the plane doesn't need so many corrections.
Thanks so much for your help. I really want to fly more now and set up other planes in my hangar to fly as well as the edge.
Tom
04-28-2013, 08:01 AM
#37
RE: nose heavy
Tom, Im glad I was able to help. When I started aerobatics set up knowledge was mainly trial and error. With RCU and other venues I attempt to shorten the path for those who will accept and try my teachings. Thank you for posting an accounting of your success as it has made my weekend just all that much better.
