Lateral balance of profiles - your method for checking?
03-15-2006 | 10:12 AM
#26
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From: Merrimack,
NH
RE: Lateral balance of profiles - your method for checking?
'Parachute' maneuver is vertical down with power at idle, then quick pull on elevator to level angle of attack, fully stalled wing, then come down in an 'elevator' maneuver, like a skydiver popping his parachute, then floating down.
03-15-2006 | 03:01 PM
#27
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From: Hagerstown,
IN
RE: Lateral balance of profiles - your method for checking?
ORIGINAL: Spacey
My best suggestion is take a plane with the motor nicely offset like they normally are with some right thrust and balance it your method. Now go back and use Dion's method to balance it and go back home and see where the lateral ended up. Definitely not in the same line. Now also as we know not a single model is built exactly perfectly so the right side of the plane and the left side would hardly ever match up exactly area wise when looking at it from above. Also the deflection of the elevator halves would never be exactly the same in flight unless you have a rock solid control system. That is why I said to use the pick up thing at home to get yourself into the ballpark and then fall back to Dion's method as that'll get you the closest if you can pull up elevator perfectly without putting aileron in. If you can do this and you don't see one wing dropping the whole time but rather the wings taking turns and so on you know you have a well balanced profile laterally.
I hope I made sense.
ORIGINAL: UltimateFlyer12
I have to disagree completely with Spacey and the reason is simple But I'll quote the designer of the Boxxer Jeremy Chinn
"While you are setting the CG, don’t forget the vertical and lateral CG’s. The plane should balance tip to tip (lateral), and should balance top to bottom. The lateral and vertical CG’s of most airplanes is on a line through the crankshaft of the motor, through the wing and the horizontal centerlines."
Funfly profiles are very forgiving. Build it straight and without warps and forget all this other BS!
I have to disagree completely with Spacey and the reason is simple But I'll quote the designer of the Boxxer Jeremy Chinn
"While you are setting the CG, don’t forget the vertical and lateral CG’s. The plane should balance tip to tip (lateral), and should balance top to bottom. The lateral and vertical CG’s of most airplanes is on a line through the crankshaft of the motor, through the wing and the horizontal centerlines."
Funfly profiles are very forgiving. Build it straight and without warps and forget all this other BS!
My best suggestion is take a plane with the motor nicely offset like they normally are with some right thrust and balance it your method. Now go back and use Dion's method to balance it and go back home and see where the lateral ended up. Definitely not in the same line. Now also as we know not a single model is built exactly perfectly so the right side of the plane and the left side would hardly ever match up exactly area wise when looking at it from above. Also the deflection of the elevator halves would never be exactly the same in flight unless you have a rock solid control system. That is why I said to use the pick up thing at home to get yourself into the ballpark and then fall back to Dion's method as that'll get you the closest if you can pull up elevator perfectly without putting aileron in. If you can do this and you don't see one wing dropping the whole time but rather the wings taking turns and so on you know you have a well balanced profile laterally.
I hope I made sense.
03-15-2006 | 07:32 PM
#28
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From: Santa MariaAzores, PORTUGAL
RE: Lateral balance of profiles - your method for checking?
ORIGINAL: majortom-RCU
'Parachute' maneuver is vertical down with power at idle, then quick pull on elevator to level angle of attack, fully stalled wing, then come down in an 'elevator' maneuver, like a skydiver popping his parachute, then floating down.
'Parachute' maneuver is vertical down with power at idle, then quick pull on elevator to level angle of attack, fully stalled wing, then come down in an 'elevator' maneuver, like a skydiver popping his parachute, then floating down.
03-16-2006 | 01:51 AM
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From: Pretoria, SOUTH AFRICA
RE: Lateral balance of profiles - your method for checking?
[/quote]
Spacey What you say makes sense to a point. If I was trying to trim a 2 meter Pattern plane or a large IMAC type plane sure I see your point. With my 4 1/2 lb 3D profile There is a easier way. Jeffro on the first page described how Morris hobbies instructed how to balance your profile. That method is great. My method grabbing the prop (with 2deg right thrust) and lifting the front wheels off the ground and hold the plane stable with the tail wheel and let the wing drop also does the trick. Just a little breese will throw a 40 size profile's wing around.
[/quote]
You know I had a very similar discussion with a guy on a local forum not too long ago where normal CG was discussed and it also came down to this bloke's TLAR method and well my using the proper determining of the mean aerodynamic chord and calculating CG from there. You know on a profile it doesn't make a huge difference sure but using the right or the TLAR method could very well mean either the life or death of the guy that reads this's Spitfire he builds a little later. I'm all for taking shortcuts when we know it's not going to kill the plane just quite possibly make it impossible to harrier (Remember all the old Katana GS threads?) but if a guy askes you how to do something make sure you give him the right/proper way to do it before you give him a shortcut and make sure you underline the dangers of taking the shortcut method on other models if it so applies. And on a side note regarding the 2meter pattern ship comment....you know these planes we fly and the way we fly them in my eyes puts them on exactly the same level of high performance that a F3A pattern ship is on. Setting it up right from the get go really makes a difference in the long run when you start demanding alot from them like I do sometimes when I fly.
Spacey What you say makes sense to a point. If I was trying to trim a 2 meter Pattern plane or a large IMAC type plane sure I see your point. With my 4 1/2 lb 3D profile There is a easier way. Jeffro on the first page described how Morris hobbies instructed how to balance your profile. That method is great. My method grabbing the prop (with 2deg right thrust) and lifting the front wheels off the ground and hold the plane stable with the tail wheel and let the wing drop also does the trick. Just a little breese will throw a 40 size profile's wing around.
[/quote]
You know I had a very similar discussion with a guy on a local forum not too long ago where normal CG was discussed and it also came down to this bloke's TLAR method and well my using the proper determining of the mean aerodynamic chord and calculating CG from there. You know on a profile it doesn't make a huge difference sure but using the right or the TLAR method could very well mean either the life or death of the guy that reads this's Spitfire he builds a little later. I'm all for taking shortcuts when we know it's not going to kill the plane just quite possibly make it impossible to harrier (Remember all the old Katana GS threads?) but if a guy askes you how to do something make sure you give him the right/proper way to do it before you give him a shortcut and make sure you underline the dangers of taking the shortcut method on other models if it so applies. And on a side note regarding the 2meter pattern ship comment....you know these planes we fly and the way we fly them in my eyes puts them on exactly the same level of high performance that a F3A pattern ship is on. Setting it up right from the get go really makes a difference in the long run when you start demanding alot from them like I do sometimes when I fly.
03-17-2006 | 09:54 PM
#30
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From: Port Edwards,
WI
RE: Lateral balance of profiles - your method for checking?
Another thing that could screw up the balance procedure with wall or parachute is if the elevator halves aren't in perfect sync with exact end-points. If this is off, even a bit, it could make things hard to figure out.
03-18-2006 | 06:45 AM
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From: Manhattan,
NY
RE: Lateral balance of profiles - your method for checking?
Another thing that could screw up the balance procedure with wall or parachute is if the elevator halves aren't in perfect sync with exact end-points. If this is off, even a bit, it could make things hard to figure out.
