RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Interesting bits in this thread the past week....just reading it for the first time on a rainy Sunday. My single prop Bravo in the foreground first flew in 2009, and immediately had a small vertical strake (about 2" high by 5" long) just behind the canopy. Before the end of 2009, it had the extension on the bottom of the rudder and ventral subfin on the fuse that extended about 8" forward of the rudder hingeline. At about that time, I also tried the fat rudder trailing edge...and immediately junked it....as others have said, there are far more efficient ways to add yaw stability (added side area is minimal drag compared to a fat trailing edge). In early 2011, the large TCan on the canopy was added which provided more knife edge power for the P11 Figure M, but also destabilized the airplane in yaw.....so I extended the subfin forward to the size seen in the picture. My 2nd Bravo was identical to the first until 2011 when I added the Contra. I added the Contra and changed nothing else (save the added 3 oz of the Contra) and the #2 was actually divergent in yaw. After a lot of tinkering, the final configuration of bits that yield the knife edge power and yaw stability I like are what is shown in the picture. Compared to the single prop, ventral fin is longer, stab SFGs added, dorsal extension added. On the Contra, I very much prefer the wing SFGs vs the TCan - while they both yield similar knife edge power, the SFGs have slightly more yaw stability in turbulent air (I have no explanation for this). The Contra Bravo has ZERO mix for knife edge, and needs absolutely none, even in knife edge loops. Both planes have a small bit of downthrust and a tiny bit of down elevator mix at low throttle. Neither have a throttle > rudder mix. Regards,
Posted on: 5/19/2013 2:18 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11516307

RE: Am I the only one who flies pattern with no mixes in their plane ??
"Trimming" happens at many levels. Straight and level hands off is always the starting point. And straight and level is even better when minimal trim and subtrim is used. Does the plane stay straight and level at different airspeeds and power settings - ie, fine adjustments to CG, thrust, and incidence can have a large effect. Trimming also includes finding the ideal CG - the one that is the best balance for control throw authority AND groove in turbulence and promotes good snaps / spins with minimal (if any) mix needed for downlines and KE flight. Trimming of control throws.....getting flying rates, snap rates, and spin rates (stand alone rates, or in Flight modes) tailored to make these maneuvers as easy and consistent as possible. Controls should feel balanced - having the exact same throw and expo alone will not work as it does not compensate for various offsets (right/left thrust, downthrust, torque, etc). Trimming for specific maneuvers/flight regimes......basic loop tracking inside/outside, large loops, square corners - the plane should not deviate in yaw or roll. Vertical lines.....the planes should not deviate in yaw, pitch, or roll. KE flight.....the plane should not roll or pitch with rudder input....even when doing KE loops. The more demanding the maneuvers, the harder it is get a plane to perform them without any electronic mixing (Pmix). Any Pmix that reduces pilot workload is a good Pmix....but.....if the same state of trim can be achieved without using a Pmix, that is preferrable. Regards,
Posted on: 9/8/2012 6:59 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11221663

RE: F3A Results - SPOILER
I'm jumping in late.......took a week off after the NATs, and then spent a week cleaning the shop and lining up experiments and testing for next year....influenced no doubt by the 74K unknowns, which is even more of an influence in strong winds. I'm not smart enough to cut/paste multiple quotes to respond to......but.....couple points I would add - I've flown identical planes side by side on the same day multiple times with the only difference being single prop vs Brenners Contra system. On a radar gun, the top speeds were equal, and when flown through the pattern, the flight times were always within 5 seconds, with the greater influence on time being the pilot, not the powerplant. Without a doubt, 100%, spiral airflow, torque, PFactor, and gyroscopics are real (just like the science says) and ARE AFFECTING our pattern models. I am not suggesting our pattern models can not be designed, trimmed, setup, etc, to greatly minimize the effects, BUT, the effects are real, and do cause trim problems if they are not addressed (and they can not truly be cancelled out), and they are all but eliminated with the Contra system. I say all but eliminated as the relative RPM / torque of each prop on the Contra is not always balanced in transient conditions. Another point on this that I will add.....maneuvers that require rolling left and right, or snapping left and right, or require both positive / negative corners are often among the most challenging....outside of the challenges to the airframes, ergonomics and habits are also factors. The ergonomic factor is simply that our hands are not symmetrical when pushing left aileron vs pulling left aileron (for the Mode 2 flyers), and the habitual factor is that most pilots simply have a preferred direction for rolling, snapping, or a preferred "sight picture" (ie, always show the canopy first when rolling). The Contra very effectively eliminates assymetries in the plane from spiral airflow, torque, etc....but it does not eliminate ergonomic assymetries and pilot preferences. The science behind all of these ideas is easy enough to research, and in my opinion, the only aspect for debate is to what degree it affects our discipline. If an airplane is trimmed to fly straight and level, and exhibits positive stability (in both pitch and yaw), are not the sum of the vector forces such that the net value is "1G" of lift? 1G being the amount of lift needed to overcome gravity. If the geometric configuration (and airspeed) of the plane is not changed, that 1G lift exists no matter what the orientation of the plane is......and that means [i]barring no other changes[/i], the plane will move to the canopy in uplines, downlines, and KE flight. The airplane does not know what attitude or orientation it is flying with, and has zero capacity to turn off the lift being produced. It is very clear to me that minimizing incidences (downthrust, positive in the wing, negative in the stab, etc) and reducing wingloading are effective at minimizing the pull to the canopy caused by 1G......but minimizing incidences and wingloading do not eliminate the pull to the canopy. That said, I have (and have flown other) planes that exhibit zero movement to the canopy in uplines and KE. The zero movement is not the product of the wings being unloaded, or not producing lift in a given attitude, but the product of changes or additions to the vector forces such that the net value of the 1G lift is altered and the new net value is 0G (zero G). In the vertical upline, the change that is introduced is added power......which IF downthrust is part of the setup will impart movement to the belly....and this also assumes constant airspeed as a change in airspeed would alter the lift from the wing as well. In KE flight, the change is the addition of beta (angle of attack in yaw), and now the fuselage is flying with some amount of slip in yaw (which is not present in level flight, uplines, or downlines). I will suggest that a properly designed fuselage in addition to producing lift in yaw also produces a slight amount of lift (-1G, negative 1 G) to the belly resulting in a net 0G trim condition when in KE. It is very easy to alter KE pitching behavior by changing the fuselage shape, or directing airflow on the fuselage......no changes to CG or incidences are required. I have flown planes that went straight down....and they did not have positive stability in pitch.....miserable to fly for pattern. With a tiny bit of down elevator mixed to low throttle, straight downlines are very possible, predictable, and consistent, and this is a product of changing the vector forces such that 0G is present (reducing the AOA of the wing to zero). My last comment on this is that the effects of 1G on a very well trimmed and setup plane can be small enough such that they are not noticeable in anything other than calm air, even with zero mixes. My Contra Bravo exhibits ZERO need for mixing (even on a 74K unknown), save a small amount of down elevator at low throttle. Motor vs engine discussion - the science is 100% on the side of motors having more torque. And that FACT alone doesn't mean all pilots will prefer electric motors as again, ergonomics and preferences come into play - ask 10 pilots to put the throttle stick at 25, 50, and 75% (without looking at the TX), and you are likely to get 10 different answers. And the throttle curve / torque / power feel is different with different prop diameters, prop airfoils, motor design, exhaust tuning, cam timing, gearing, KV, etc. The very nature of electric motors is that they actually govern RPM to an extent.....the motor "wants" to run at a given RPM which is dictated by KV * voltage. If the actual RPM is less, the motor pulls more amps to get to that RPM, and if the RPM is more, the amps drop. This means the electric will add power whenever airspeed drops (going to a vertical climb, or adding drag with rudder or aileron inputs), and the electric will reduce power whenever airspeed increases (going into a dive). This is very different than glow which drops RPM some amount when entering a climb, and noticeably increases when going into a dive. FWIW, it is easy enough to do the math to figure out the average current draw of an electric flight - I typically average about 32 amps (~ 90 amps peak) with my geared Neu setup (single prop or Contra) for a mix of P/F13 in variable wind conditions and an average flight time of about 5:45 enter box to exit box and average discharge of 3,600 mah. This is flying at sea level - even at 1,000', the mah used drops by 5% or more (flight times stay the same). Very long slow flights in calm air can be as low as 25 amps average and very big fast flights in high winds can be as high as 40 amps average. Motor vs engine discussion - the science is 100% on the side of the engines having the greater amount of energy available (since fuel capacity is essentially unlimited). The greatest stress caused by the 74K unknowns (especially in windy conditions) is on the pilots, then the airframes, then the powerplants, and most certainly the electrics feel the stress more than the slimers (tic). And in the case of the US NATs, electric still came out on top, and in my opinion, will continue to do so for all the positives offered by electrics. Do I anticipate some changes in electrics? Absolutely...and I also anticipate changes in airframe designs (electric or glow) for the 74K unknowns, and to better exploit the advantages a Contra system offers. Aside from the aerodynamic demands from the increased amount of KE flight and snaps, the 74K unknowns also put a premium on having a wider speed envelope available - and my personal opinion is that this ultimately favors the electric simply because a good ESC can provide more (electronic) braking than the mechanical braking action of a glow engine. And perhaps most importantly - anothe Princess Bride quote - Vizzini: ......INCONCEIVABLE. Inigo Montoya: You keep using that word. I do not think it means what you think it means. Regards,
Posted on: 8/12/2012 8:26 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11190353

RE: What is a good ESC for f3a
[quote]ORIGINAL: cchariandy Any comments on the performace of the YGE 90 brake feature? Colin [/quote] I've been told by others that have run the YGE and the Castle that the YGE brake is more limited in strength available. Regards,
Posted on: 7/20/2012 6:08 AM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11162285

RE: Plettenberg 30-10? 30-9? or Advance 30-10?
Yepe, http://www.rcuniverse.com/forum/m_10298506/anchors_10306208/mpage_1/key_/anchor/tm.htm#10306208 Post 2 has info on settings for the ESC. Only thing that has changed since that post is the current software version is 4.01. Rune, I am Castle sponsored, so I have the most direct experience with the Castle line of ESCs, on both inrunners and outrunners. The brake problem (as you described it) is not unique to Castle; it happens with other brands as well - I am not trying to start a brand war, just pointing out the problem is not unique to Castle. When ESCs engage the brake, they are effectively shorting the motor wires together, and while this is happening, the ESC can not follow the timing of the motor. Going back to sensored motors and ESCs is one possible fix. If your priority for an ESC is very strong braking power for a direct drive motor on a low drag plane, then I agree, the Castle may not be the best option. On the other hand, if your priorities are efficient, durable, programming ease, lots of features, low cost, and good customer service, Castle is very hard to beat in those respects. Regards,
Posted on: 7/20/2012 5:56 AM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11162271

RE: Plettenberg 30-10? 30-9? or Advance 30-10?
On most combinations of plane, prop, and flying style, brake %s greater than 30% may result in abrupt restarts when the throttle is advanced after the brake was engaged. The restarts can be abrupt enough to kick loose the spinner or prop. Regards,
Posted on: 7/18/2012 8:31 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11160647

RE: Plettenberg 30-10? 30-9? or Advance 30-10?
Nickolay, Low Timing 8 khz or OR for PWM Do not exceed 30% for brake strength You will not see much (if any) increase in power with more aggressive settings, but you may see some added heat and mis-timing in the air. Even on low timing, the HV80 can advance to 24 degrees IF the ESC "thinks" it is of benefit. Regards,
Posted on: 7/17/2012 7:46 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11159385

RE: Pattern ship winglet.
[quote]ORIGINAL: serious power [/quote] Hi Dave, I don't doubt ,at all, what you say or have found. With that said I will add the following; It was CPLR that brought the the T Can,, to this party. He has removed the vertical component and now sits the 'winglet' directly on top of the fuz,, . I'm assuming he finds it as good or maybe even better. All I am saying is that there is ,so far anyway, no one size fits all solution but there are clearly benefits to these 'winglets'. Brian [/quote] Brian, We are in agreement that CPLR was the first to use a Tcan configuration, and I am not doubting the effectiveness on his planes. My point (perhaps lacking clarity) was more that simple strakes could provide similar effects as the TCan. And we are certainly in agreement that a given winglet, TCan, or strake should not (and from my experience does not) be expected to have the same result on every design. Nat Penton was the first I know of to use extensively use strakes - however - I think Nat was coming from different direction. Nat wasn't using small strakes to tweak the airflow around a "cool" looking fuse. Nat ditched the aesthetics and used a minimal fuse with gobs of airfoiled side area where it counts the most - at the CG. Regards,
Posted on: 7/8/2012 8:34 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11148207

RE: Pattern ship winglet.
I don't have a wind tunnel, but at the end of it all, theory is just that, and actual flight results matter the most. I can do a lot of testing cheaply and quickly with nothing more than an exacto, depron, tape, and foam safe CA [:D] Regards,
Posted on: 7/8/2012 9:59 AM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11147522

RE: Pattern ship winglet.
[quote]ORIGINAL: grotto2 Excuse me if I'm skeptical. Even if the canalizer works as described, I still don't know a) what to expect when it's added (plus or minus), b) how big it should be, c) what it should be shaped like or d) where it should be placed. Once on my plane, I will be doomed to report that it 'feels' better, lest I admit that I'm a lesser pilot than Mr. Big-Name. With the technology we have today we still use guess-and-by golly fad approaches for airplane design. I think we could do better. [/quote] Ron, I'm not personally sold on the horizontal component of the Tcan.....depending on the fuse shape and location, a very simple vertical strake can be very effective. The biggest effect is on the pitching behavior in KE. Most modern designs tend to pitch to the belly in KE - unless the CG is quite forward, which causes other trim problems. On every design I've tested a strake or canalizer, adding the device will impart a pitch to the canopy in KE, and the amount of pitch to the canopy is somewhat proportional to the size of the Tcan/strake. I've seen a 1/2" x 6" fin change KE coupling by 3%....very easy way to eliminate Pmix on some planes. Regards,
Posted on: 7/8/2012 9:44 AM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11147506

RE: F3a The Future
LOL!!!! We used to joke about how the patterns had changed such that almost 50% of the time we flew inverted......now....it is quite possible that an F3A unknown sequence could have 50% of the time consumed by KE and integrated maneuvers. Don is spot on with his comments about the maneuvers driving the innovation....and as he points out.....its really the challenge is primarily met with innovation in the airplane designs.....not the cost of the components. That said, I really like flying my Contra, and I expect to see it grow rapidly in popularity after the US NATs this year. Regards, [quote]ORIGINAL: Don Szczur We will see a transformation in pattern in exactly three weeks. Aircraft designs will be optimized for constant speed and knife edge and constant rolling loop maneuvers going forward. Watch Christophe and Benoit's as well as other European new designs. Joseph is thinking hard on a new design as well. Guys pay attention this is the next level in competition in the finals F3A unknown manevues will drive the next generation of designs. These are K6 (trust me this is not as in K6 kindergarden) but I'd call the rolling horizontal 8 with 4 rolls in each loop more like a K10. At Poconos, when we walked up to the pilot box and the judges had masters scoresheets still on their clipboards, I said lets fly Masters.. inverted entry? maybe... Dave jokingly challenged to fly the entire masters sequence entering in knife edge, and was serious. I did not take him up on that challenge (calling would be a bit of a challenge on the spot) but this is serious guys and separator maneuvers related to complexity (but here is a hint- the maneuvers can be done with both a YS 170 as well as a $149.99 Eflight 160 and by the way with power curve dialed back to 80 percent, for the eflight motor on the front of the Pegasus, so this in fact shatters the perception about powerplant cost...) knife edge triangle loop (inverted entry). Knife edge triangle loop with snap on top leg knife edge vertical 8 knife edge vertical 8 with half rolls (you will like this one) knife edge cuban 8 with rolls knife edge reverse cuban 8 (more difficult than the knife edge cuban 8) rolling horizontal figure 8 family with 1, 2 or 4 rolls in each loop (P.S. I'd recommend doing this on the simulator first) And finally, what you've all been waiting for, the double keyhole... See y'all F3A propectives at the NATS and bring the popcorn.. Don [/quote]
Posted on: 7/1/2012 8:19 PM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11139343

RE: ESC Options - Jeti?
"What are the latest opinions for best ESC with respect to cost, weight, and performance?" RE cost and performance - I think Castle wins that easily. RE Weight - make sure you are comparing weights with equal lengths of wiring, or the amount of wiring you will actually be using in your installation. The Castle comes with long wires and it quite easy to save 1 - 1.5 oz with an efficient installation. RE Motors - dependign on your priorities, the Neu F3A-1 is in the middle of the price range of options you listed, and it is tops for power and torque (and has same gearbox maintenance requirements as Hacker inrunner). Regards,
Posted on: 6/19/2012 7:22 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11123646

RE: Ice 100 or Motor?
Connectors between the motor and ESC are EVIL!!! [:D] I much prefer soldering the wires together......1/2 the solder joints, and no possibility of a loose plug which can arc, build heat, and in extreme cases start a fire. Glad it was an easy fix. Regards,
Posted on: 6/6/2012 7:37 PM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11109504

RE: Coupling question
A couple points - IF Joe tweaks his stab/elevators and it fixes his KE problem, the tweak will result in zero adverse trim changes and will not compromise a single maneuver up to and including FAI. If the tweak doesn't fix the problem, them something else is the culprit (again, I don't advise the tweak until all other geometric / trim consideration are addressed first). I don't fly around trim problems.....bad use of my limited brain power :) I'd have never cut a wing in half 4 times so I could fly around a roll coupling issue or any other problematic trim setups. I never use a Pmix or aerodynamic device that does not make the plane fly better - and by better I mean the same quality maneuver can be replicated with reduced pilot workload. And the Pmix is the last resort. I don't remember the year (Brian may remember), but some number of years ago, I flew with Bryan at a practice field at the NATS (I think it was Kokomo), and I got a flight on his plane. Trim condition on the plane was superb - straight KE, straight verticals, no bad behavior. Except.....I found the plane very touchy.....it was for me very tailheavy (but not unlike many setups I have and continue to see). I know since that time, Bryan has been setting up his planes with a more forward CG, and while I have not flown one of his planes recently, I am sure the forward CG setup is at least as good or better than the tailheavy setup (otherwise the tailheavy setup would still be used). In 2008, I was extremely happen with the trim on my Bravo, and it had zero aerodynamic devices on it. It began sprouting aerodevices when the schedules changed and increased the demand on the planes. I tested many aerodevices to get the performance improvements I wanted, and if I had the time, I'd build an entirely new plane, but I don't have that time....in part because I spend it practicing instead. I've helped trimmed many different designs using my methods and found that the same size does not fit all...the idea that one trim technique or process is equally suited for all designs is nonsense......and suggesting a particular design is flawed or junk if it doesn't respond to a particular trim process is also nonsense......different planes have different strengths / weaknessess which are very often the deliberate choice of the designer based on what they choose to prioritize. And pilots can choose to fly designs which are best suited to their style / strengths / weaknesses. I have spent a limited time trimming Hebert designs....quite simply they have never been flown in the Northeast US in substantial numbers, so I've not spent much time trimming them. So far as the spiral airflow theory......how much effect spiral airflow has on a design can and certainly does vary with the design. But...having flown F3P foamies and F3A planes with single and Contra setups, spiral airflow is absolutely real. I would never suggest there is only one way to design or trim for it. Again, I took a pair of identical Bravos and changed 1 to a Contra. In steady state low beta KE flight (thus negating PFactor and gyroscopic precession), the single prop needs the tweak in the stab to KE straight while the Contra needs no tweak. On the Bravo (and many other designs), I've yet to experience a negative effect from tweaking the stab (to the extent needed to fix the KE assymetry). From my experience with the Bravos, I find it very unlikely that a single design plane will fly equally well with a single prop and Contra using the same trim setup. It is possible that such a design exists now, or may exists in the future, but I find that possibility unlikely. Hey Tony!!! Looks like you, Matt, Bryan, and I all agree about an aft CG being BAD!!!! :) Regards,
Posted on: 6/5/2012 11:47 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11107495

RE: Coupling question
[quote]ORIGINAL: RC_Pattern_Flyer Just questioning your deduction in the results of your test Dave... Was is the spiral airflow that was changed or was it the reduction in torque being cancelled. Just curious how to we would decide which is causing the need for stab adjustment, torque or spiral flow? Respectfully curious... Chuck [/quote] Both torque and airflow are being changed. So far as what is causing the trim change in pitch....it is the spiral airflow. Torque is oriented on the roll axis, not the pitch axis. Regards,
Posted on: 6/4/2012 5:40 PM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11106513

RE: Coupling question
I figured out "tweaking" the stabs in 1989 while trimming a Tipo.....it pulled to the canopy in KE with right rudder, but was dead straight in KE with left rudder. Much of the prevailing wisdom at the time was to shift the CG aft slightly to have a plane that pulled less to the canopy in KE with right rudder, and pitched an equal amount to the belly in KE with left rudder. I found by slightly reducing the incidence of the left stab and increasing the incidence of the right stab an equal amount, I was able to have the airplane pitch an equal amount to the canopy in either KE. I then moved the CG back slightly (resulting in a slight bit of down elevator trim) and the plane had zero pitch coupling in KE. I cut the wing in half 4 times, adjusting the dihedral each time until there was zero roll coupling in KE. Electronic mixing is always the last resort [:D] Every plane I have owned since that time has had some amount of twist in the stabs (or elevators if the stab is fixed) to balance the right/left KE behavior. I've never had to change rudder trim or aileron trim because of twisting the stab, and I've never seen loop tracking suffer from the twist in the stabs. June 2011, I had 2 Bravos within 1 oz flying weight of each other (#1 being 1 oz heavier than #2), and to the best of my ability to accurately measure incidence, control throw, CG, etc, they planes were identical. Both had the same amount of twist in the stab, and both had the same behavior in KE. I replaced the single prop Neu setup on the #2 plane with a Contra unit, and moved the lipos slightly aft to maintain the CG. The #2 plane now weighed 1 oz more than #1 and in right rudder KE it pitched to the belly, and in left rudder KE it pitched an equal amount to the canopy. I removed the twist from the stabs, and the plane had zero pitch coupling on either side. My conclusion - Spiral airflow is real, and twisting the stabs is an effective way to reduce or completely mitigate some of the undesireable effects, and I've found zero down sides to twisting the stabs. I don't advocate twisting the stabs until all other parameters are addressed - proper geometric alignment of all surfaces, all surfaces warp free, etc. I've flown a number of Hebert designs over the years (including some of his personal planes) and all have flown well.....so I would never suggest that Brians trim methods are BS.....but as with many things, there is more than one way to skin a cat. Joe - try the stab / elevator tweak, and let us know how it works. Regards,
Posted on: 6/4/2012 5:10 PM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11106468

RE: Coupling question
What you are describing can happen even with a perfectly straight airplane, in which cas the culprit is spiral airflow. The expensive fix is counter rotating props. The less expensive fix is to decrease the incidence (drop LE; raise TE) in the right stab and increase the incidence of the left stab an equal amount. The AOA of the right stab dominates pitch behavior with left rudder KE, and vice versa. If the stabs are not adjustable, you can still make this "tweak" if the elevators use separate servos or a "Y" pushrod. Moving the CG forward will tend to reduce the amount of differential behavior in the left and right KE. Regards,
Posted on: 6/3/2012 5:58 PM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11105181

RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Brian, Matching the apparent :) speed with any of the prop sets is not a problem. For my plane, I am finding it can be flown at a very slow constant speed even with the higher pitched props, just by using less throttle, and when it gets windy, I don't make any changes, I just go faster to avoid larger crab angles. Based on the judges training at the 2011 WC...I'm flying at about 170m, and completing P13 box entry to box exit in about 5:15 to 5:30. On an 80F day, I typically see 130F on the motor and 110-115F on the TP G6 5000 Prolites. I've used as little as 2800 mah on a day with light winds. Smart bull!!! Regards,
Posted on: 5/22/2012 12:53 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11090696

RE: Proposed 2013/2014 Sequences
+1 on not changing Advanced.... So far as the downwind Avalanche....it has been used quite a bit in the past (probably during a time when Tony was taking a break from pattern)...certainly in Masters, and I think in Advanced. And the triangle snap loop in Masters has also started downwind....putting the snap into the wind has been the preference for most. Certainly there is a difference between a straight line snap and Avalanche, but I really haven't seen any problems with the downwind Avalanche. Regards,
Posted on: 5/22/2012 12:45 PM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11090682

RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Brian, I find the 22x18/20 combo to be painfully slow for all weather conditions and styles - unless the goal is to crawl around the sky at 140 meters in very light winds. I find it to be very lacking in top end speed for windy conditions, and in most conditions, the downlines are much slower than needed (ie, slower than the horizontal flight). My goal with the Contra setup was/is to be able to match the top end speed of my favored single prop setup and not give up anything in terms of efficiency or downline braking. My "benchmark" is the 20.5x14.5 Falcon on the Neu F3A motor in my Bravo - the plane I flew for judge warm ups at the 2011 WC. The Bravo has a rather thick wing TE, so it is not the lowest drag plane around. With the ~21x22 props, I find the performance to be very comparable to a 21x14 for top speed, and the Contra has slightly more authority in the climb and the downlines are slower - no brake on the Contra but with brake on the 21x14. At this point, in light winds, I rarely exceed 75% power with the Contra or a single prop....but....in heavy winds, I am running the Contra quite hard, and am looking to essentially gain a little more top end speed at the expense of downline braking (which I have an excess of). Regards,
Posted on: 5/22/2012 7:11 AM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11090278

RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
[quote]ORIGINAL: serious power [quote]ORIGINAL: MTK [/quote] Saw Dave Lockhart's contra driven Bravo flying for the first time at the contest this past Saturday. The drive system provided outstanding performance, especially with Dave's new props and gear ratio. The sound was quite cool, especially the beats, similar to a twin with engines slightly out of sync. Later, Dave let me fly it. Performance to burn and it was solid down to a crawl Nice job! [/quote] Guys, Spill please !! 'Dave's props and gear ratio' what's are these. Brian [/quote] Brian, The props are "development" props from fall 2011, and they made the rounds in the US to a couple Contra flyers. Basically, they are 22x20" props modified by Chip. Front cut to 21" and rear cut to 20.75", and about 22" of pitch on both with APC style tips. I'm running the 9.89 gearset. I suspect the new 22x22 props cut to 21 and 20.75" will give similar performance, but I haven't gotten around to doing that yet. Regards,
Posted on: 5/21/2012 4:47 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11089444

RE: R/C Aerobatics Contest Board Initital Vote
So one proposer was on the Contest Board. What were the affiliations of the other proposers? Regards,
Posted on: 5/18/2012 9:38 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11085817

RE: Proposed 2013/2014 Sequences
Tony is correct about the Advanced Sequence. It was not slated to be changed, but there was quite a stir about whether or not it would/should be. The Sequence Committee developed a new one so as to not be caught off guard. I've not heard any updates, but I feel quite comfortable in suggesting IF it were officially changed, there would be complaints about it being changed too frequently.....and IF it is not changed, there will be a similar number of complaints. I want to be very clear that a number of changes were made in the Sequences during development based on feedback from multiple sources. The bulk of the feedback was positive, and continues to be positive. I certainly didn't get everything I wanted, but, I think majority rule is what the Seq Committee followed. The Seq Committee has zero expectation of making everyone happy....looks like that expectation has been met (not unlike in the past). The Seq Committee also had the expectation that there would be a measurable amount of Monday morning quarterbacking after the Sequences were announced....that expectation has also been met (not unlike in the past). It's quite rare that the Seq Committee is filled with a full slate of active members that have actually read and pay attention to the guidelines. Joe L was extremely dedicated to the Seq Committee for many years, and spent a huge amount of time improving the process and clarifying the guidelines, which, contrary to some astray thought processes, are a living document that has been continually updated for several cycles now. I've said it many times, if someone does not like the way the Sequences are developed, then take an active part in the group and/or organize a legit survey to accurately poll the masses and see just what difficulty level each class should be at. I talk with a lot of people all over the country, and reguarly coach pilots in all classes, and from what I can see, by and large, the difficulty level of each class is pretty close to what is desired by the majority. Masters has for many years been problematic in that it is difficult to distinguish the best pilots at the NATs....I don't see this changing as the majority of local Masters flyers (which is the overwhelming majority, not the Masters NATs finalists) don't want an increase in the difficulty level of Masters and don't want another FAI class absent the FAI pilots. Regards,
Posted on: 5/18/2012 9:36 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11085814

RE: Proposed 2013/2014 Sequences
Any discussion / concern about the length of the Sequences and consideration for glow / electric is nonsense. At this point, the majority of the Seq Committee actually flies electric. In the midst of a season, my flight times are generally within +/- 5 seconds for a given Sequence. To recall, the proposed Masters, 2011 Masters, P11, and P13 were all within about 15 seconds and mah usage was very similar. There were a fair number of comments received during the testing period of the sequences. The majority were positive, so changes were not made. Having worked on the Seq Committee the majority of the cycles since 1989, it is simply impossible to make all the changes requested and minor tweaking of the sequences can go on endlessly. I am not aware of any feedback / input/ commentary that was not reviewed by the Seq Committee. There is not enough room in any of the Sequences for all of the maneuvers everyone wants to see. Never has been, never will be. Use too many "classic" maneuvers and the Sequence is criticized for being old, stale, nothing new. Use too many "FAI" maneuvers, and it is too much like FAI. Use too many "IMAC" maneuvers, it is too much like IMAC. Use too many new maneuvers or traditional maneuvers in new spots, and the "classic" flyers think the classic way was better. Over the years, I've learned its not possible to look, review, and even fly a Sequence and accurately compare it to another Sequence - yes, flying gives a general sense, and can point out some pinch spots or challenges - and they might be the same. A pinch spot for one guy is a brilliant combination of maneuvers to teach box and airspeed manangement to another guy....again, no Sequence will make everyone happy. The Seq Committee has used a number of tools to analyze the types of maneuvers and elements in various sequences - amount of inverted flying, number of rolls, snap rolls, and spins of each type, 45 degree elements, crossbox maneuvers - this is done very analytically to remove personal preferences and semantics, ensure guidelines are followed, and ensure a good progression through the classes. Regards,
Posted on: 5/18/2012 6:09 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11085555

RE: Nuance
[quote]ORIGINAL: nonstoprc Somebody mentioned (on a different rcu thread) that the Advance can reach 6200rpm with 21x14. Just wonder if 6200 is the pretty much the top limit for 21x14 or 20.5x14. [/quote] Summertime temps w/ TP G6 5000 25C.....6700 is about right on the Neu for 20.5x14, 21x14, 20.5x14.5. Static RPM from the Castle ICE data logging, which in my experience is very accurate for RPM. Regards,
Posted on: 5/15/2012 6:09 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11082279

RE: Classic Pattern Engines Available
Thanks guys....all plugs are gone Odds of me ever running a classic 60 2C piped setup are slim to none...... I do have a small pile of glowplugs.....any interest (send a PM)? 6 K&B 1L 3 Rossi 5 3 Rossi 4 2 Rossi 3 3 Rossi 2 2 Rossi 1 Regards, -
Posted on: 2/14/2012 11:51 AM by Author "DaveL322" in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10957755

RE: Rules History, EU1-A Pics
Just wanted to thank everyone for the pics I recieved of EU1-As. The "Project Pattern Redux" series in Flying Models has started with the March 2012 issue and includes pics of a Circus Circus themed EU1-A from Chris McMillin and a T-Bird themed EU1-A from Sam DiMao. I did a pretty extensive review of all the AMA and FAI rulebooks I could get my hands on (most are now posted on CPA and NSRCA websites) and the March and April FM columns review the evolution/history of pattern from the ballistic pattern time to the current day. May will be the start of Europa Pro LT build. Regards,
Posted on: 2/8/2012 5:57 PM by Author "DaveL322" in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10950495

RE: CC ICE2 80HV current reading calibration
FWIW, When I first started running the ICE ESCs, they did seem pretty consistent ESC to ESC, and the voltage and RPM readings were very closely matched to the Eagletree and an optical tach. Regards,
Posted on: 1/30/2012 3:12 PM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10935715

RE: CC ICE2 80HV current reading calibration
Luke, I noticed the same thing several years ago when I started running the ICE ESCs - logging showed higher amps and mah than my Eagletree. What amount of the differences do you think could be attributed to connectors / solder joints? Regards, Dave
Posted on: 1/30/2012 6:39 AM by Author "DaveL322" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10934865

RE: F3a Unlimitted
Unfortunately, he was in a car accident, but is ok and getting caught up. Regards,
Posted on: 1/26/2012 9:16 AM by Author "DaveL322" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10928792