tail heavy, wing loading?
03-27-2007 | 03:13 PM
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From: kansas City,
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tail heavy, wing loading?
I am just about done restoring and modifying an old Thunder Tiger Skylark 40 size trainer. Since I can't track down the original plans, I'm using this calculator to find a COG range,
http://adamone.rchomepage.com/cg_cal...&result10=0.68
I think I may be tail-heavy. Right now my wing loading is 17.5 oz./sq.ft. (with empty tank). If I need to add nose weight, how much wing loading is too much for a trainer? It has a well broken-in Magnum 40. A previous owner already epoxied in several bars of lead behind the firewall which are still there. But I think my mods may have added some tail weight (metal pushrods, larger elevator and rudder).
The receiver is as far forward as possible, and the battery is built in under the tank, assuming it as forward as possible. Is lead behind the firewall the only/best way to add to add nose weight?
http://adamone.rchomepage.com/cg_cal...&result10=0.68
I think I may be tail-heavy. Right now my wing loading is 17.5 oz./sq.ft. (with empty tank). If I need to add nose weight, how much wing loading is too much for a trainer? It has a well broken-in Magnum 40. A previous owner already epoxied in several bars of lead behind the firewall which are still there. But I think my mods may have added some tail weight (metal pushrods, larger elevator and rudder).
The receiver is as far forward as possible, and the battery is built in under the tank, assuming it as forward as possible. Is lead behind the firewall the only/best way to add to add nose weight?
03-27-2007 | 03:27 PM
#2
RE: tail heavy, wing loading?
trainers can handle a higher wing loading due to the high lift airfoil an old guide would be one pound weight per 100 square inches of wing area.you could try using a heavier spinner or nose wheel or even a weighted prop nut,weight needs to be as far forward as possible.hope you reduce the throws on the larger control surfaces as things could git touchy ,that and a rear cg is a disaster waiting to happen.most trainners will balance on the main spar which should be the thickest part of the wing.
03-27-2007 | 08:56 PM
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RE: tail heavy, wing loading?
I think I'm good! My CG is right on the main spar with tank empty, my CG (or finger balance point) is within the limits according to the calculator with or without the ailerons included in the wing chord. I will have an instructor take it up and trim it for me just to make sure because I am a newbie. The throws are toward the low end.
Aerowoof, one more question: Wing loading w/empty tank is about 18. With my wing area at 780 sq. in. are you telling me by your rule of thumb this plane could handle 7.8 lbs. without being a tank? Right now it wieghs in at abt. 6 lb. Doesn't engine size also factor in?
And what about prop size and pitch? I'm wanting it to be a "gentle" trainer at this point. (Maybe this should be in the aerodynamics forum). It has a 10 X 6 prop now. Help a newbie get his head around thrust etc. Thanks.
Aerowoof, one more question: Wing loading w/empty tank is about 18. With my wing area at 780 sq. in. are you telling me by your rule of thumb this plane could handle 7.8 lbs. without being a tank? Right now it wieghs in at abt. 6 lb. Doesn't engine size also factor in?
And what about prop size and pitch? I'm wanting it to be a "gentle" trainer at this point. (Maybe this should be in the aerodynamics forum). It has a 10 X 6 prop now. Help a newbie get his head around thrust etc. Thanks.
03-28-2007 | 12:47 AM
#4
RE: tail heavy, wing loading?
ORIGINAL: mbilar1
I think I'm good! My CG is right on the main spar with tank empty, my CG (or finger balance point) is within the limits according to the calculator with or without the ailerons included in the wing chord. I will have an instructor take it up and trim it for me just to make sure because I am a newbie. The throws are toward the low end.
Aerowoof, one more question: Wing loading w/empty tank is about 18. With my wing area at 780 sq. in. are you telling me by your rule of thumb this plane could handle 7.8 lbs. without being a tank? Right now it wieghs in at abt. 6 lb. Doesn't engine size also factor in?
And what about prop size and pitch? I'm wanting it to be a "gentle" trainer at this point. (Maybe this should be in the aerodynamics forum). It has a 10 X 6 prop now. Help a newbie get his head around thrust etc. Thanks.
I think I'm good! My CG is right on the main spar with tank empty, my CG (or finger balance point) is within the limits according to the calculator with or without the ailerons included in the wing chord. I will have an instructor take it up and trim it for me just to make sure because I am a newbie. The throws are toward the low end.
Aerowoof, one more question: Wing loading w/empty tank is about 18. With my wing area at 780 sq. in. are you telling me by your rule of thumb this plane could handle 7.8 lbs. without being a tank? Right now it wieghs in at abt. 6 lb. Doesn't engine size also factor in?
And what about prop size and pitch? I'm wanting it to be a "gentle" trainer at this point. (Maybe this should be in the aerodynamics forum). It has a 10 X 6 prop now. Help a newbie get his head around thrust etc. Thanks.
