Biplane question
09-06-2006 | 03:36 PM
#1
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From: , QC,
Biplane question
I have a general idea for a design vaguely reminiscent of a staggerwing beech... same chord and lenght on both wings , retractable landing gear , .91 (4s)
my questions
#negative stagger: 50% ( more? less?)
#motor ,wing ,stab incidence : all at 0 degrees ( comments?)
#where do I put cg ? I read midway point of line between 23% chord of wings (comments )?
#distance between two wings?
#stab on motor center line ( comments ?)
# how high over the bottom wing do I put the motor center line (trust line ) ?
SO ... your 2cents are welcome
aviador
my questions
#negative stagger: 50% ( more? less?)
#motor ,wing ,stab incidence : all at 0 degrees ( comments?)
#where do I put cg ? I read midway point of line between 23% chord of wings (comments )?
#distance between two wings?
#stab on motor center line ( comments ?)
# how high over the bottom wing do I put the motor center line (trust line ) ?
SO ... your 2cents are welcome
aviador
09-06-2006 | 10:18 PM
#2
RE: Biplane question
#negative stagger: 50% ( more? less?)
That seems like a lot to me but if you like the look of it then go for it. I believe the original Beech stagger was more like 20%.
#motor ,wing ,stab incidence : all at 0 degrees ( comments?)
If you're looking for a very neutral handling model then sure, why not. For more of a general sport model that will spend more time upright than inverted then go for zero on the engine and stab and +1 to +2 degrees on the wings.
#where do I put cg ? I read midway point of line between 23% chord of wings (comments )?
This "trick" will work for two equal sized and identical layout wings but it's not really the "right" way. But use it since it works in this case. But for a 0-0-0 or even the 0-1-0 layout this is FAR too far forward and you'll find yourself adding a HEAP of up trim. With a close to neutral engine-wing-stab setup shoot for starting at 30% and be prepared to sneak it back a bit more than that even.
#distance between two wings?
Biplanes generally need between 0.7C to 1.5C between the wings. The greater the gap the less drag and lost lift due to interferance. A nice compromise range is typically reported to be 0.9 to 1.2C.
#stab on motor center line ( comments ?)
Anywhere close is fine. Unless you're shooting for a TOC contender in which case you'll have to experiment or pick someone elses brain.
# how high over the bottom wing do I put the motor center line (trust line ) ?
Again, anywhere close to center to slightly low. TOC contender option? See above.
Other than that make it look nice.... the sky LIKES nice planes so they fly better....
That seems like a lot to me but if you like the look of it then go for it. I believe the original Beech stagger was more like 20%.
#motor ,wing ,stab incidence : all at 0 degrees ( comments?)
If you're looking for a very neutral handling model then sure, why not. For more of a general sport model that will spend more time upright than inverted then go for zero on the engine and stab and +1 to +2 degrees on the wings.
#where do I put cg ? I read midway point of line between 23% chord of wings (comments )?
This "trick" will work for two equal sized and identical layout wings but it's not really the "right" way. But use it since it works in this case. But for a 0-0-0 or even the 0-1-0 layout this is FAR too far forward and you'll find yourself adding a HEAP of up trim. With a close to neutral engine-wing-stab setup shoot for starting at 30% and be prepared to sneak it back a bit more than that even.
#distance between two wings?
Biplanes generally need between 0.7C to 1.5C between the wings. The greater the gap the less drag and lost lift due to interferance. A nice compromise range is typically reported to be 0.9 to 1.2C.
#stab on motor center line ( comments ?)
Anywhere close is fine. Unless you're shooting for a TOC contender in which case you'll have to experiment or pick someone elses brain.
# how high over the bottom wing do I put the motor center line (trust line ) ?
Again, anywhere close to center to slightly low. TOC contender option? See above.
Other than that make it look nice.... the sky LIKES nice planes so they fly better....
