Trim Chart
03-19-2005 | 12:41 AM
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From: Maple Ridge,
BC, CANADA
Trim Chart
Im new to C/L. Having huge fun flying and destroying junk. I have a couple of kits built and more to build next winter. I would like to know more about setting up C/L for the first flight. Is there a trim chart available so the first flight wont be a disaster? For example where do the lines lead out from the wing tip and why? How much tip weight is required? Is the engine offset or not? Thank for any help.
Kiwipaul
Kiwipaul
03-19-2005 | 01:15 AM
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From: SHARPSBURG,
KY
RE: Trim Chart
Hello KP
glad to have you join us. I'm a sorta rookie at this too, but I have been getting a lot of good answers to my questions here. If you will look thru the second post down, ADJUSTABLE FLAP AND ELEVATOR, there is a lot of good info there that I have been getting from others. I haven't asked about the tip weight yet. kd posted a trim chart yesterday and I really like it, but it is after the first flight, I think, and which way to go from there. The first thing everyone said is to put adjustable leadouts on your build. Here is my block for the leadouts and then installed. More to come.
glad to have you join us. I'm a sorta rookie at this too, but I have been getting a lot of good answers to my questions here. If you will look thru the second post down, ADJUSTABLE FLAP AND ELEVATOR, there is a lot of good info there that I have been getting from others. I haven't asked about the tip weight yet. kd posted a trim chart yesterday and I really like it, but it is after the first flight, I think, and which way to go from there. The first thing everyone said is to put adjustable leadouts on your build. Here is my block for the leadouts and then installed. More to come.
03-19-2005 | 01:34 AM
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From: SHARPSBURG,
KY
RE: Trim Chart
Okay kp,
I'm at work and have to run off from time to time to check on things but I'll try to pass on what I know, which isn't much. I'm a retread, flew CL many years ago and now I'm back. Still fly RC.
As for engine offset, most don't use it, just mount the engine straight to the planks. Maybe put a thin plate under it first to keep the flanges fron sinking into the wood.
I have just finished my first CL in a long time and am waiting for the weather to get good enough to fly, maybe this weekend.
I'm not exactly sure about how much tip weight, I built a weight box in my outer wing tip and right now the plane will laterally balance slightly heavy on the outer wing, and I will probably add from that point about 1 ounce. Maybe somebody else will jump in here and give some more suggestions.
I'm at work and have to run off from time to time to check on things but I'll try to pass on what I know, which isn't much. I'm a retread, flew CL many years ago and now I'm back. Still fly RC.
As for engine offset, most don't use it, just mount the engine straight to the planks. Maybe put a thin plate under it first to keep the flanges fron sinking into the wood.
I have just finished my first CL in a long time and am waiting for the weather to get good enough to fly, maybe this weekend.
I'm not exactly sure about how much tip weight, I built a weight box in my outer wing tip and right now the plane will laterally balance slightly heavy on the outer wing, and I will probably add from that point about 1 ounce. Maybe somebody else will jump in here and give some more suggestions.
03-19-2005 | 04:18 PM
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From: Northampton, UNITED KINGDOM
RE: Trim Chart
Try NO tip weight. Stopped using it years ago. You might need a bit more area on the inboard wing, but I think the most important trim adjustment (along with CG) is the correct leadout rake. Tip weight is dead weight.
03-19-2005 | 06:32 PM
#5
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RE: Trim Chart
Actually, tip weight is still an important component in the trim process, one of the first things you do. The first test of the trim on a new ship is whether it flies wings level, upright and inverted. That is adjusted by tip weight and tweeking the flaps for roll adjustment. A stunter that rolls in or out in manuevers is a scary thing to fly.
The jury is still out on unequal wing panels. I think from my study of the subject, that most newer designs have equal panels, or if they are offset, it is only a little, maybe 3/8 inch.
Have a look at 2bflyinging's thread on adjustable flaps and elevators for a link to the Paul Walker trim flow chart. Paul won the Nationals in CLPA 5 times running, plus one World Champs, so he's likely a pretty good resource. RW and I have been having a running conversation on this very subject. Welcome aboard!
Kelvin
The jury is still out on unequal wing panels. I think from my study of the subject, that most newer designs have equal panels, or if they are offset, it is only a little, maybe 3/8 inch.
Have a look at 2bflyinging's thread on adjustable flaps and elevators for a link to the Paul Walker trim flow chart. Paul won the Nationals in CLPA 5 times running, plus one World Champs, so he's likely a pretty good resource. RW and I have been having a running conversation on this very subject. Welcome aboard!
Kelvin
03-19-2005 | 07:26 PM
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From: Northampton, UNITED KINGDOM
RE: Trim Chart
I agree on the wing panel size and also that it's an alarming prospect to have a full-on stunter trying to roll up the lines at you. If it loses tension during either inside or outside manouvres, then it's more likely due to building inaccuracies. If it rolls in on both then it could be dealt with by increasing offsets (engine, rudder and/or leadouts) or perhaps by increasing inboard aileron area or movement (assymetric throws - I've seen assymetric throws work very effectively).
For a tip weight to work effectively it needs to pivot around a centre of mass. For a free flying RC model, small tip weights are very effective in straightening out loops since they act, more or less, on the centre-line of the model. For a control line model the effective centre of mass (and centre of pressure) laterally is more dynamic regardless of tip weights and is likely to be somewhere along the inboard wing, considering line mass and drag. In fact, tip weights are more likely to have adverse effects during square manouvres when there may be abrupt loss of air speed. In this case the tip weight momentum would yaw the model into the circle. Not, I suppose, what is required.
In practice I guess these effects are very small, but its been a long time since I have used tip weights in a stunter. Although perhaps a little different, years ago we experimented with tip weights in combat wings when they were usually shown on the plans. They seemed to fly better without weights and they certainly were none the worse by their absence.
I think tip weights add one deficiency to compensate another. I feel there are better ways to trim a C/L model without adding tip weight (or any weight for that matter).
Cheers,
For a tip weight to work effectively it needs to pivot around a centre of mass. For a free flying RC model, small tip weights are very effective in straightening out loops since they act, more or less, on the centre-line of the model. For a control line model the effective centre of mass (and centre of pressure) laterally is more dynamic regardless of tip weights and is likely to be somewhere along the inboard wing, considering line mass and drag. In fact, tip weights are more likely to have adverse effects during square manouvres when there may be abrupt loss of air speed. In this case the tip weight momentum would yaw the model into the circle. Not, I suppose, what is required.
In practice I guess these effects are very small, but its been a long time since I have used tip weights in a stunter. Although perhaps a little different, years ago we experimented with tip weights in combat wings when they were usually shown on the plans. They seemed to fly better without weights and they certainly were none the worse by their absence.
I think tip weights add one deficiency to compensate another. I feel there are better ways to trim a C/L model without adding tip weight (or any weight for that matter).
Cheers,
03-20-2005 | 07:47 PM
#7
Senior Member
RE: Trim Chart
Hmm, Mick, you're making me think....I've seen tip weight cause hinging (rolling) in square corners. My last-years Pathfinder hinged with a half ounce of tip weight. But as you noted, it flies fine with no weight. I have always thought that tip weight worked to counteract the overshoot of the lines as they change direction going into a square corner. A stunter can hinge to the inside or outside.
You are certainly right on that a tethered airplane doing maneuvers is a very dynamic animal. Especially the CP and it's effects on stability. I'm trying to visualize how tip weight would cause yaw, though.
You are certainly right on that a tethered airplane doing maneuvers is a very dynamic animal. Especially the CP and it's effects on stability. I'm trying to visualize how tip weight would cause yaw, though.
03-20-2005 | 07:52 PM
#8
Senior Member
RE: Trim Chart
Here is what I was thinking of:
>Got a chance to do a little flying today and am slowly
>working through getting the engine and trim on my Legacy
>somewhere in the ballpark. Present problem is it looses line
>tension on insides and I can see the top of the outboard
>wing all the way through an inside loop. I really can't tell
>but think it does the opposite on outsides.
>
>Wings seem to be level both upright and inverted. Rudder is
>adjustable and slightly offset, engine just enough to be
>sure it isn't pointed in. Seems to be flying tangent to the
>circle as the wheels are lined up in level flight. Have
>about an ounce of tip weight plus all the heavier wood in
>the outboard wing. Any thoughts on how to proceed to get
>this solved?
More tipweight is the simple answer. The "wing level" in upright and inverted flight is a *very* insensitive measurement. Put tip weight in until it stops rolling in at you, then see how it looks in level flight.
I might guess that you have too much rudder offset/leadout rake, but you can't really tell until you get enough tip weight in.
Brett
This is from a post by Brett Buck over at Stuka Stunt.
>Got a chance to do a little flying today and am slowly
>working through getting the engine and trim on my Legacy
>somewhere in the ballpark. Present problem is it looses line
>tension on insides and I can see the top of the outboard
>wing all the way through an inside loop. I really can't tell
>but think it does the opposite on outsides.
>
>Wings seem to be level both upright and inverted. Rudder is
>adjustable and slightly offset, engine just enough to be
>sure it isn't pointed in. Seems to be flying tangent to the
>circle as the wheels are lined up in level flight. Have
>about an ounce of tip weight plus all the heavier wood in
>the outboard wing. Any thoughts on how to proceed to get
>this solved?
More tipweight is the simple answer. The "wing level" in upright and inverted flight is a *very* insensitive measurement. Put tip weight in until it stops rolling in at you, then see how it looks in level flight.
I might guess that you have too much rudder offset/leadout rake, but you can't really tell until you get enough tip weight in.
Brett
This is from a post by Brett Buck over at Stuka Stunt.
03-20-2005 | 09:43 PM
#9
RE: Trim Chart
First flights are always a bit of a worry because you never know what's going to happen so there's a couple of things to check. First is that it balances no further back than what the plans call for. If it's got flaps then sight along them from behind the elevator and make sure they're dead even with each other. I move the elevator until I can just barely see either the top or bottom surface of one flap then look at the other flap (don't move your head, just flick your eyes across).
Now the bits you're wondering about. Hold the model by the spinner or prop nut and under the tail and the outboard wingtip should drop. If it needs half to one ounce of weight on the inboard tip to balance then it should be about right for a first flight. Now hold it by both leadouts so that the controls are roughly neutral and let it dangle. The fuselage should be pointing slightly down at the nose which means the mid point of the leadouts is slightly behind the CG. I like to have my leadouts as close as possible to each other, about 3/8", so there's the least variation between full up and full down. But with them this close they have to be staggered in length so the connections can never foul.
For the "why's" of doing this, the tip weight basically is to balance the weight of the lines but later it becomes a fine tuning trim. Having the leadouts exit slightly behind the CG balances the drag of the lines which tries to yaw the nose inwards. I don't think there's much point in having any engine offset but if a few degrees gives you peace of mind then it won't hurt.
For what it's worth regarding tip weight and fine tuning, half an ounce extra on one of my models totally transformed the way it flew. Before adding it, the turn up into a wingover was almost impossible to do straight and the top turn in an hourglass was free flight, literally!! The problem being that the model was rolling slightly (outboard tip up) which reduced line tension to something less than zero. That 1/2 ounce extra during a 20G turn becomes a lot of weight at the tip.
Now the bits you're wondering about. Hold the model by the spinner or prop nut and under the tail and the outboard wingtip should drop. If it needs half to one ounce of weight on the inboard tip to balance then it should be about right for a first flight. Now hold it by both leadouts so that the controls are roughly neutral and let it dangle. The fuselage should be pointing slightly down at the nose which means the mid point of the leadouts is slightly behind the CG. I like to have my leadouts as close as possible to each other, about 3/8", so there's the least variation between full up and full down. But with them this close they have to be staggered in length so the connections can never foul.
For the "why's" of doing this, the tip weight basically is to balance the weight of the lines but later it becomes a fine tuning trim. Having the leadouts exit slightly behind the CG balances the drag of the lines which tries to yaw the nose inwards. I don't think there's much point in having any engine offset but if a few degrees gives you peace of mind then it won't hurt.
For what it's worth regarding tip weight and fine tuning, half an ounce extra on one of my models totally transformed the way it flew. Before adding it, the turn up into a wingover was almost impossible to do straight and the top turn in an hourglass was free flight, literally!! The problem being that the model was rolling slightly (outboard tip up) which reduced line tension to something less than zero. That 1/2 ounce extra during a 20G turn becomes a lot of weight at the tip.
03-21-2005 | 09:17 PM
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From: SHARPSBURG,
KY
RE: Trim Chart
hello again kd
You said the plane is rolling in at you on insides. Now remember, it's been awhile since I have flown CL but I don't remember any of my planes rolling in on me whether upright or inverted. I made sure that the outboard wing was slightly heavier than the inboard with the leadouts, and I figured that would be a good starting point. So if I get the plane wanting to roll the outside wing in at me during any maneuvers I might need to add some tip weight, right?
But will it work the same on an inside loop as it will if you are inverted and do an outside loop? Let me make sure I get this right. An inside loop is anytime the elevator goes up and the plane does a 360 degree turn and ends up the way it was going. If you are inverted about 6 feet off the ground, giving down elevator does a loop also but this is an outside loop, although it is really an inside loop that is started in the inverted position. I'm really confused now.
I had the plane outside Sat morn. getting ready to fire it up for an engine run and it started raining. Packed it all back in. Too windy Sun. so I just watched the NASCAR race. I spent 13 years building engines for Dash series and Busch series cars for the number 27 team, A.W. Kirby driving. But he got killed in a motorcycle wreck about 3 years ago and I retired from that. Haven't been to a race since, but I still like to watch.
My next question was gonna' be about tip weight, but you pretty well answered that. I'll fly with what I have now and try adding if it's needed. I know I'm not too heavy on the outboard.
You said the plane is rolling in at you on insides. Now remember, it's been awhile since I have flown CL but I don't remember any of my planes rolling in on me whether upright or inverted. I made sure that the outboard wing was slightly heavier than the inboard with the leadouts, and I figured that would be a good starting point. So if I get the plane wanting to roll the outside wing in at me during any maneuvers I might need to add some tip weight, right?
But will it work the same on an inside loop as it will if you are inverted and do an outside loop? Let me make sure I get this right. An inside loop is anytime the elevator goes up and the plane does a 360 degree turn and ends up the way it was going. If you are inverted about 6 feet off the ground, giving down elevator does a loop also but this is an outside loop, although it is really an inside loop that is started in the inverted position. I'm really confused now.
I had the plane outside Sat morn. getting ready to fire it up for an engine run and it started raining. Packed it all back in. Too windy Sun. so I just watched the NASCAR race. I spent 13 years building engines for Dash series and Busch series cars for the number 27 team, A.W. Kirby driving. But he got killed in a motorcycle wreck about 3 years ago and I retired from that. Haven't been to a race since, but I still like to watch.
My next question was gonna' be about tip weight, but you pretty well answered that. I'll fly with what I have now and try adding if it's needed. I know I'm not too heavy on the outboard.
03-22-2005 | 08:15 PM
#11
Senior Member
RE: Trim Chart
ORIGINAL: 2BFlying
hello again kd
You said the plane is rolling in at you on insides. Now remember, it's been awhile since I have flown CL but I don't remember any of my planes rolling in on me whether upright or inverted. I made sure that the outboard wing was slightly heavier than the inboard with the leadouts, and I figured that would be a good starting point. So if I get the plane wanting to roll the outside wing in at me during any maneuvers I might need to add some tip weight, right?
Yep, like kp described above, the outboard tip should drop a little if you hold the plane by the tailpost and the spinner. You might not see any roll in loops that are done gently. (This rolling motion is called "hinging" in the hobby.) But if you start doing square corners-the square loops and eights, reverse wingover, the hourglass-then you may see hinging start to show up in the hard turns.
One thing that's happening is that the lines are having to change direction at the same time as the airplane. The lines sag from the G loads, pulling down on the inboard tip. The ship rolls or hinges. The outboard tip may be visible over the fuselage. If there is too much tip weight, then the outboard tip will go down. So the weight gets adjusted 1/4 ounce or so at a time until the hinging is gone. You can add weight until the tip hinges down and then back off a little.
If the plane rolls in regular round loops, it's probably a warp rather than tip weight at fault.
But will it work the same on an inside loop as it will if you are inverted and do an outside loop? Let me make sure I get this right. An inside loop is anytime the elevator goes up and the plane does a 360 degree turn and ends up the way it was going. If you are inverted about 6 feet off the ground, giving down elevator does a loop also but this is an outside loop, although it is really an inside loop that is started in the inverted position. I'm really confused now.
Think about being in the cockpit of the model. It flies a loop. If your head is pointed into the loop, it's an inside manuever. If your head is pointed out, it's an outside. A figure eight, for instance, has an inside and an outside half. The effects of weight are the same either way. Too much tip weight will always pull toward the outside of the loop or in the direction of the G loads.
Remember, on a new plane, the first step is to make sure that it flies with the wing parallel to the ground, both upright and inverted. It helps to have someone outside the circle watching for this. The usual cause is a warp. Steam and twist, or twist and reheat the covering if it's covered in film. Sometimes guys add a samll trim tab to the outboard wing. Get it flying level, then look at the landing wheels while in flight. If you can see both, then it may be flying yawed. Move the leadout guide until the plane's tangent to the circle. Then you can bang some hard corners and see how the tip weight is doing.
I had the plane outside Sat morn. getting ready to fire it up for an engine run and it started raining. Packed it all back in. Too windy Sun. so I just watched the NASCAR race. I spent 13 years building engines for Dash series and Busch series cars for the number 27 team, A.W. Kirby driving. But he got killed in a motorcycle wreck about 3 years ago and I retired from that. Haven't been to a race since, but I still like to watch.
That's neat that you built engines. I have some old buddies who dirt race in Texas, but no one who aspires to NASCAR. I remember Kirby-but didn't know about his wreck. I'm sorry to hear about that. I still like stock car racing, too. But I'm getting a little fed up the with the TV coverage. It is slowly sounding more like World Wild Wrestling or something. Somtimes I wish they would just shut up and show the race.
Our 20.2 inches of snow are melting pretty quickly. Some day soon it'll be warm....See you later.
Kelvin
My next question was gonna' be about tip weight, but you pretty well answered that. I'll fly with what I have now and try adding if it's needed. I know I'm not too heavy on the outboard.
hello again kd
You said the plane is rolling in at you on insides. Now remember, it's been awhile since I have flown CL but I don't remember any of my planes rolling in on me whether upright or inverted. I made sure that the outboard wing was slightly heavier than the inboard with the leadouts, and I figured that would be a good starting point. So if I get the plane wanting to roll the outside wing in at me during any maneuvers I might need to add some tip weight, right?
Yep, like kp described above, the outboard tip should drop a little if you hold the plane by the tailpost and the spinner. You might not see any roll in loops that are done gently. (This rolling motion is called "hinging" in the hobby.) But if you start doing square corners-the square loops and eights, reverse wingover, the hourglass-then you may see hinging start to show up in the hard turns.
One thing that's happening is that the lines are having to change direction at the same time as the airplane. The lines sag from the G loads, pulling down on the inboard tip. The ship rolls or hinges. The outboard tip may be visible over the fuselage. If there is too much tip weight, then the outboard tip will go down. So the weight gets adjusted 1/4 ounce or so at a time until the hinging is gone. You can add weight until the tip hinges down and then back off a little.
If the plane rolls in regular round loops, it's probably a warp rather than tip weight at fault.
But will it work the same on an inside loop as it will if you are inverted and do an outside loop? Let me make sure I get this right. An inside loop is anytime the elevator goes up and the plane does a 360 degree turn and ends up the way it was going. If you are inverted about 6 feet off the ground, giving down elevator does a loop also but this is an outside loop, although it is really an inside loop that is started in the inverted position. I'm really confused now.
Think about being in the cockpit of the model. It flies a loop. If your head is pointed into the loop, it's an inside manuever. If your head is pointed out, it's an outside. A figure eight, for instance, has an inside and an outside half. The effects of weight are the same either way. Too much tip weight will always pull toward the outside of the loop or in the direction of the G loads.
Remember, on a new plane, the first step is to make sure that it flies with the wing parallel to the ground, both upright and inverted. It helps to have someone outside the circle watching for this. The usual cause is a warp. Steam and twist, or twist and reheat the covering if it's covered in film. Sometimes guys add a samll trim tab to the outboard wing. Get it flying level, then look at the landing wheels while in flight. If you can see both, then it may be flying yawed. Move the leadout guide until the plane's tangent to the circle. Then you can bang some hard corners and see how the tip weight is doing.
I had the plane outside Sat morn. getting ready to fire it up for an engine run and it started raining. Packed it all back in. Too windy Sun. so I just watched the NASCAR race. I spent 13 years building engines for Dash series and Busch series cars for the number 27 team, A.W. Kirby driving. But he got killed in a motorcycle wreck about 3 years ago and I retired from that. Haven't been to a race since, but I still like to watch.
That's neat that you built engines. I have some old buddies who dirt race in Texas, but no one who aspires to NASCAR. I remember Kirby-but didn't know about his wreck. I'm sorry to hear about that. I still like stock car racing, too. But I'm getting a little fed up the with the TV coverage. It is slowly sounding more like World Wild Wrestling or something. Somtimes I wish they would just shut up and show the race.
Our 20.2 inches of snow are melting pretty quickly. Some day soon it'll be warm....See you later.
Kelvin
My next question was gonna' be about tip weight, but you pretty well answered that. I'll fly with what I have now and try adding if it's needed. I know I'm not too heavy on the outboard.
03-23-2005 | 02:42 AM
#12
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From: Maple Ridge,
BC, CANADA
RE: Trim Chart
Gentelmen thank you for your help. 
I will study hard and make notes.[:-] I promise to be a good student and not bust any more balsa. 
Kiwipaul
I will study hard and make notes.[:-] I promise to be a good student and not bust any more balsa. Kiwipaul
