ORIGINAL: Rendegade
ORIGINAL: flyncajun
When I started designing Pattern Aircraft
I was told the Stab had to be lowered to keep the airplane from pitching to the belly on Rudder( wrong)
I was told SSS was Causing the airplane to pitch to the Belly on left rudder, But right rudder ,,Not so much (wrong)
I was told down thrust was how you kept an airplane from pulling to the canopy in a verical up line (wrong)
I was told you can`t get the mix out of a airplane because the SSS put unequal pressures on the surfaces,you just have to live with it (wrong)
I was told Wide tall fuses would fly terribe in the wind(wrong)
I was told a heavy airplane flew better in the wind (wrong)
I was told the airplane had to be built with wing, stab set to zero (wrong)
I was told there is no way to perform a Knife edge loop with no Mix purley on rudder command (wrong)
I was told anhedral stabs countered too much dihedral in the wing (wrong)
I was told you had to run the C/G back around 35 % so the airplane used just a little down elevator (wrong)
I was told you need minimun of 2 degrees right thrust (wrong)
I was told to start out with 1.5 deg down thrust (wrong)
I was told a forward canopy rolled better (wrong)
I was told fixed gear were less drag than retracts (wrong)
I was told there had to be a left rudder mix at low throttle (wrong )
I was told you cannot use Sharp leading edges on your wings and stabs the airplanes would be pitchy in flight (wrong)
I was told you cannot use counter balances on ailerons (wrong)
I was told you had to run deferential on ailerons to roll axially (wrong)
I WAS TOLD ALL BIPES HAD TO HAVE THE WINGS AT DIFFERENT INC. NEG ON TOP POS ON BOTTOM (WRONG)
I WAS TOLD TO USE UP THRUST ON THE BIPE( WRONG)
I WAS TOLD TO GIVE UP ON THE BIPE (WRONG)
the guy who told be that went back to it after seeing mine HAHA
i WAS TOLD BIPES WERE TO COMPLICATED TO HAVE NO MIX (WRONG)
I WAS TOLD TO BE COMPETITIVE TODAY I HAD TO GO TO ELECTRIC (WRONG) had to throw that one in LOL
Bryan, I thought I'd just put this over in another thread before it degenerates any further.
Can you tell us how you've come up with these, and more importantly how you've overcome some of these issues? This isn't meant to be an attack, I'm seriously interested, as I'm sure are quite a few other modellers.
Speaking for myself, If you played around in this game long enough, you've heard and/or read every one of these "fixes, dosand don'ts", several times over. There are others as well....
From personal experience I can say that a rearward CG makes the plane work okay in inverted flight but makes it uncertain in pitch when upright. Throw in anhedral stab with a rear CG and cross wind flying creates a whole nother set of problems.
I've found that stab anhedral does detractsome wing dihedral. Flatten the stab and yaw response is different, all other things equal. I've found that a small amount of down thrust does correct a pitch to canopy in the full power upline. But it can create other issues so I use the technique sparringly. A slight positive in the stab helps correct both an upline and inverted flight when CG is forward, between 25% and 30% MAC
No way anyone will convince me that a heavy model flies better than the exact same design does10-15% lighter. On CG, I tend not to useCG as a trimming criterion. I tend to calculate it'sideal position based on areas, area distributionand moments, and add 15% static margin. There is nothing magic about 15% static margin, it is something that I've settled on with experience.
I love the flightenvelope ofsmall LE radii. Occasionally I used larger radius on the wing LE in particular and have always been disappointed, Add to the list that thick wings create more lift than thin wings. Baloney! Thick wings are sluggish in pattern apps, plain and simple....
I don't subscribe to the tiny wing syndrome that has invaded patterndom. Properly designed, large wings have all the attributes we want plus they reduce loading, which enlarges a model's flight envelope. I don't subscribe to flared rudders or thick TE's. I don't subscribe to canalizers. Dorsals and ventrals, definitely, and not just on fuselages....
I don't think I've ever wound up with a model set at zeros all around. Tried to tweek the model's angles based on need rather than preconceived notions, particularly over the past 20 years as trim technique has been learned and refined. I think that's where Bryan is coming from too
Have never used aileron differential on a pattern model, only trainers with rectangular wings.
I use and recommend high taper ratios in wings, at least 3:1 root to tip. My current design sports 3.4:1. This enables a significant increase in wing area with no down sides in roll response. It also produces greater capability in cross wind.
I use and recommend low TVC (tail volume coefficient). I use TVC in pattern models around 0.6 and it has served great over a couple decades. Some, very few, commercially available models are getting down close to this at present. Most still play in the 0.8 TVC region.Stated simply,lower TVC produces more spritely performance which is super duper in todays schedules
I've found that, in every case where a single prop was turning CCW (front view), for a given and identical amount of aileron deflection, right roll has always been faster than left roll. I've always had to increase left roll deflections to compensate. Having flown Dave L's contra Bravo, I saw and felt that problem go away. This seems to imply that SSS is the culprit
Regards SSS, Bryan and I differ in our opinions a bit; But I'm not sure whether Bryanis actually sayingthat it doesn't exist. I think he believes it does but that he simply doesn't care since his trimming reduces it's effects to negligible levels. I believe that roll response difference is directly attributable to SSS. This could be proven far easier in an E set-up where motor can be set-up to run in either direction. I would love to hear results from someone with an E-plane that is willing to try the experiment.....